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IPR-06-05

1. 2 0E 06 Y 1 5E 06 a te o ER 5 A X 1 0E 06 a 5 0E 07 Q 0 0E 00 i 2005 09 15 2005 09 15 2005 09 16 2005 09 16 2005 09 16 2005 09 16 2005 09 16 2005 09 16 2005 09 16 23 35 23 55 00 15 00 35 00 55 01 15 01 35 01 55 02 15 Date and time Figure 11 Initial peaks from the circulating pulses in the test section as monitored by the GM probe 32 Effective doserate in test section loop 2005 09 16 kl 00 2005 09 29 kl 12 2 5E 06 3 2 0E 06 1 5E 06 4 Jill y NM ng Discontinuity due to power failure 1 0E 06 ae INN i i Ih Alan MO NUN PA 5 0E 07 i MH hana hal IA N Co o 0 0E 00 Date and time Figure 12 Effective dose rate during the first two weeks after injection 3 2 2 Samplings A total of 12 samplings of the test section groundwater were done according to the procedure described in Appendix B In addition a sample was taken directly before the injections as a reference groundwater without tracers A written instruction for sampling has been used and the sampling method worked as planned however the operation of the needle valve requires some practical training in order to keep the pressure disturbances low Sampling of the first guard section was done 7 times and of the pilot borehole once at the end of the experiment This sampling was done by opening of a sampling valve for each circulation system in the
2. 57 O Equipment maintenance A maintenance plan should be produced for moving parts in the system such as the circulation pump piston o rings in the pressure regulator etc Necessary maintenance should preferentially be done before or after experiment phases PLC automatic security functions The automatic security functions in the PLC InTouch should be invented and adjusted after consideration Electrical power supplies It is recommended to install UPS backup for level indicators RNI instruments and to re establish UPS backup for the HPGe detector or install a separate UPS for the HPGe It should be considered to install voltage monitoring after earth fault breakers and auxiliary contacts on the fuses in the distribution boxes 58 References Allison J D Brown D S and Novo Gradac K J 1990 MINTEQA2 PRODEFA2 A geochemical assessment model for environmental systems version 3 0 user s manual Environmental Research Laboratory Office of Research and Development U S Environmental Protection Agency Athens Georgia 106 p Andersson P Byeg rd J Nordqvist R and Wass E 2005 TRUE Block Scale continuation project BS2B tracer tests with sorbing tracers Swedish Nuclear Fuel and Waste Management Company SKB IPR 05 01 Behrens H New insights into the chemical behaviour of radioiodine in aquatic environments in Proc Environmental migration of long lived radionuclides IAEA Wien 1982 Byeg rd J Joh
3. The preparations of the stock solutions at Baslab the transport by car to sp HRL and the transport through the airlock into the glove box were done according to the plan However the work to transfer the stock solutions from the vessels to the tubing loops was hindered by the central position of the flow cell in the glove box The flow cell placement made it necessary to work with one hand only which was extremely difficult Therefore the box door on the right side had to be opened The flow cell was placed centrally in order to facilitate calibration however it needs to be placed in the inner right corner as was originally planned The recommendation is to rebuild the stand so that the flow cell can be easily disconnected from the stand and moved from the corner placement to the central placement on occasions of calibration The injections were done as described in section 2 3 2 The second injection loop contained some nitrogen gas which caused a pressure dip at the injection The nitrogen gas was probably sucked in during the transfer of the solutions from the vessels by moving the tube end over the solution surface With a changed placement of the flow cell as described above better control of such operations can be achieved by easier handling and better visibility in the glove box 31 Mixing in the test section KA3065A03 1 The circulation time was approximately 30 to 40 minutes as can be seen in Figure 11 where the injected puls
4. LS LS Pump Filter RS Flow Electro Pressure Valve Injection Valve meter chemical regulator pressur cell meter Sealing PU Double packer PEEK y spectrometry Figure 2 Schematic diagram of experimental system for monitoring and sampling solutions from the test section and the inner guard section The total lengths given are measured from the borehole casing An on line measurement of gamma radiation is installed in the guard section circulation but not shown in the figure 12 1 2 Objectives Before the start of the long term experiment a functionality test with short lived radionuclides was performed during September to October 2005 The results are presented in this report The objectives of the tests were mainly to e Test the complete experimental set up with respect to functionality and safety including Individual functions of circulation equipment pressure regulator sensors monitoring systems alarms remote access to computers backup of data etc Functions and equipment at Baslab the radiochemistry lab The transport of samples between Baslab and the LTDE site Radiation protection services and needs e Develop and test the sampling and injection procedures in the test section and to check that appropriate mixing of the injected tracer solutions can be obtained e Investigate if sorption processes on the stub surface can be monitored with the prese
5. LTDE Hydraulic conditions of the LTDE experimental volume results from Pre tests 0 1 6 Swedish Nuclear Fuel and Waste Management Company SKB IPR 05 25 Widestrand H Andersson P Byeg rd J Skarnemark G Sk lberg M and Wass E 2001 In situ migration experiments at sp Hard Rock Laboratory Sweden results of radioactive tracer migration studies in a single fracture Journal of Radioanalytical and Nuclear Chemistry 250 3 501 517 Widestrand H and Byeg rd J 2005 Teknisk beskrivning av f ltexperiment med radioaktiva sp r mnen i sp laboratoriet LTDE funktionalitetstester med kortlivade radionuklider 2005 Swedish Nuclear Fuel and Waste Management Company internal document in swedish Winberg A Hermanson J Tullborg E L and Staub I 2003 Long Term Diffusion Experiment Structural model of the LTDE site and detailed description of the characteristics of the experimental volume including target structure and intact rock Swedish Nuclear Fuel and Waste Management Company SKB IPR 03 51 Yoshida Y and Shibata M 1999 Establishment of Data Base Files of Thermodynamic Data developed by OECD NEA Part II Thermodynamic data of Tc U Np Pu and Am with auxiliary species JNC Technical Report INC TN8400 2004 025 2004 in Japanese Waste Isolation Research Division Waste Management and Fuel Cycle Research Center Japan Nuclear Cycle Development Institute JNC Database Version 011213
6. sp Hard Rock Laboratory LTDE Long Term Diffusion Experiment Functionality tests with short lived radionuclides 2005 Henrik W idestrand Johan Byeg rd Susanne Borjesson Anette Bergelin Eva Wass Geosigma AB January 2006 International Progress Report IPR 06 05 k K mbr nslet ingAB Swedish Nuclear Fuel and Waste Management Co Box 5864 SE 102 40 Stockholm Sweden Tel 08 459 84 00 46 8 459 84 00 Fax 08 661 57 19 46 8 661 57 19 ske sp Hard Rock Laboratory Report no IPR 06 05 Author Henrik Widestrand Johan Byeg rd Susanne B rjesson Anette Bergelin Eva Wass Checked by Erik Gustafsson Approved Anders Sjdland Aspo Hard Rock Laboratory LTDE Long Term Diffusion Experiment Functionality tests with short lived radionuclides 2005 Henrik W idestrand Johan Byeg rd Susanne Borjesson Anette Bergelin Eva Wass Geosigma AB January 2006 No F79K Date January 2006 Date 2007 08 15 Date 2007 09 27 Keywords Crystalline rock Fractured rock Transport properties Diffusion Sorption Diffusivity In situ measurements Radionuclides Tracers This report concerns a study which was conducted for SKB The conclusions and viewpoints presented in the report are those of the author s and do not necessarily coincide with those of the client Abstract Within the frame of the LTDE project in situ studying of diffusion and sorption processes over longer time scales a fu
7. the STT1 b test within the TRUE 1 experiments Widestrand et al 2001 On the other hand inert behaviour of iodine was observed in the TRUE BS continuation project Andersson et al 2005 It was suspected that the different behaviour of iodine was caused by sorption on equipment materials in the TRUE 1 experiment The high redox potential gives Np V O2 as major Np species which is known to sorb weakly compared to the Np IV which undergoes hydrolysis and sorbs strongly Cadmium chloride species dominate the Cd speciation which corresponds well to the intermediate sorption of Cd Lu and Hf are expected to be strongly hydrolysed and also show a relatively strong sorption Cs sorption is relatively strong which is in accordance with earlier field test observations Ba IT data was relatively uncertain due to the low activity amount of the tracer An uncertainty analysis indicated that Ba II was non or weakly sorbing less sorbing than iodine 1 4E 03 el O Cs E Ca2 Cd2 Filtrated sample 20 nm m Luilll A Hf IV 1 2E 03 i pieza nm e Np V O2 3 a E 1 0E 03 z 2 j E 8 0E 04 i 3 Ezra ANA I 6 0E 04 TEN o 4 0E 04 O 2 0E 04 40 o 2 gt O a O 0 0E 00 4 0 0E 00 5 0E 00 1 0E 01 1 5E 01 2 0E 01 2 5E 01 3 0E 01 Elapsed time d Figure 16 Relative concentration versus elapsed time curves for samples dots and on line measurements lines in linear scale The radioactivit
8. when evaluating the final diffusion experiment Table 5 Radon emanation from different materials at sp HRL Sample Radon emanation Atoms 22Rn s m LTDE stub and slimhole surfaces 600 KA3065A03 1 2005 10 12 Laboratory experiments with crushed materials SKB IPR 02 68 Fine grained granite sp HRL 160 sp diorite sp HRL 10 Mylonite Feature A TRUE 1 lt 11 3 3 5 20 nm filtered sampling The 20 nm filtered sample Whatman Anotop 20 nm showed no clear differences in concentrations neither relative the previous and following samples nor to the on line measurements see Figure 16 Consequently sorption to colloidal particles or microbes in the groundwater larger than 20 nm is not indicated to occur to any major extent 3 3 6 Microbe analysis The water sample analysed for microbes shows an average value of 3 3E5 cells per ml This is 6 times lower than was measured at LTDE in 2002 but much higher than the value obtained after equipment cleaning and flushing of the borehole in 2003 about 1E3 cells per ml The value is relatively high for deep groundwaters but not unusual for this depth see Figure 15 for a comparison of measurements One of the microbe types was large which indicates that it was growing and lived under good conditions Pedersen 2005 39 Depth m 1000 1500 o 10 10 10 10 10 10 10 10 10 Total cells cells mr Figure 15 Placement of the
9. 3E 1 0 2 0 27 Ka 1 10 E 3 m Ka 1 10 E 3 m kg Ca ll lt 3E 4 P Not modelled Ka 2 3 E 5 m Ka 2 100 E 6 m kg Ball lt 6E 3 P Not modelled Ka 6 8 E 4 m Ka 2 50 E 4 m kg Cd ll 2E 2 1 3E 2 1 6E 2 Lu II 4 43 5 E Hf IV 13 13 15 Np v O gt 2E 2 1 6E 2 2E 2 A Value is obtained from sorption experiments using the analogous tracer Sr B Estimated maximum value based on measurement uncertainty Note that sorption was to weak to be statistically verified for Ca and Ba 3 5 Test section volume estimations Calculation of the test section volume based on the measured dilution of the tracers gives a volume of 930 to 970 ml at 80 filled pressure regulating cylinder which corresponds to a maximum volume of 1030 ml The geometrical calculations performed estimates the volume to 880 to 950 ml at 80 filled cylinder and 960 to 1030 at 100 which agrees well with the dilution measurement A rough calculation of the circulated volume based on the circulation time of the injected pulses 35 to 40 minutes and the flow rate 16 ml min gives a circulated volume of 600 ml This indicates that stagnant volumes are existing which is also indicated by the relatively long time needed to obtain a good mixing in the system 43 3 6 On line measurements of E and pH Measurements of pH and E were performed during a two months period Figures 18 and 19 The electrodes were calibrated before and after the measurement and the difference fo
10. Anderson with help from David Parkhurst A few organic species have been omitted Delta H of reaction calculated from Delta H of formations given in thermo com V8 R6 230 8 Mar 2000 Parkhurst D L and Appelo C A J 1999 User s guide to PHREEQC Version A computer program for speciation batch reaction one dimensional transport and inverse geochemical calculations U S Geological Survey Water Resources Investigations Report 99 4259 310 p 59 Pedersen K 2005 Analys av f rekomst av bakterier i LTDE 2005 09 21 Microbial Analytics Sweden AB Pehkonen J 2005a Tryckkompenserad glaselektrod Swedish Nuclear Fuel and Waste Management Company internal document SKB MD 433 YYYY 01 in progress Pehkonen J 2005b Y Y Y Y Tryckkompenserad referenselektrod Swedish Nuclear Fuel and Waste Management Company internal document SKB MD 433 YYYY 01 in progress Vilks P 2004 Review Long Term Diffusion Experiment Swedish Nuclear Fuel and Waste Management Company internal document Vilks P Miller N H 2005 Status report on 2004 supporting work for SKB s long term diffusion experiment Report No 06819 REP 01300 10098 R00 Nuclear Waste Management Ontario Power Generation Wacker P Berg C and Bergelin A 2004 Oskarshamn site investigation Complete hydrochemical characterisation in KSHO1A Swedish Nuclear Fuel and Waste Management Company SKB P 04 12 Wass E 2005 Long Term Diffusion Experiment
11. Cs Cs 132 6 47 2000 Ba n p gt Cs Cs 136 13 16 50 Ba n p gt Cs La 140 1 68 200 Ba n gt Ba decay gt Lan la and or fission of impurities of Isotopes obtained by irradiation of impurities in the BaCO3 2350 Na 24 0 623 4000 Na n Na K 42 0 515 100 K n gt k As 76 1 1 300 As n gt As Br 82 1 47 200 Br n Br 1 131 8 02 50 fission of impurities of U Lu 177 6 71 400 Lu n gt Lu Au 198 2 69 200 Aufn Au A Refers to the activity at the time for the injection i e 4 days after the end of the irradiation 1 0505 E gt PR As 76 559 keV 4 Na 24 1369 keV Na 24 AO A r 412 keV 05 132 668 keV from 2754 keV Ba 131 La 140 10000 124keV 328 kev a Br 82 776 keV 7 3 FR I ry ai 82 1044 keV al K 42 1524 keV 1000 MA ee E Lu 177 N ae IT ir on Te 82 828 keV DN 7 113 keV Cs 136 818 keV Mp ipaa sa rot arica al Counts 00 Br 82 698 keV A EE Br 82 698 keV Br 82 554 keV La 140 1596 kev I al Br 82 1475 keV J La 140 487 keV 10 Cs 132 465 keV Br 82 1317 keV mr E Cs 129 372 keV ma 1 131 364 keV 0 00 512 00 1024 00 1535 00 2047 00 Energy keV Figure A 1 Spectrum for the y spectrometry measurement of the Cs stock solution 62 Sample measurement Since the decay of Cs is not associated with any measurable y radiation the much less selective liquid scintillation c
12. bacteria measurement at LTDE in September 2005 green square and December 2002 red square in a matrix from other deep groundwaters 3 4 Tracer concentration measurements 3 4 1 Injected radioactivity The total amounts of injected radioactivity are presented in Table 1 The injected radioactivity is calculated based on the difference measurements of the amount of radioactivity that was transferred from the stock vessels to the injection loops 95 of solution 1 and 99 of solution 2 were transferred and injected the remainders were returned to Baslab in the original stock solution vessels 3 4 2 Tracer concentration time curves Relative concentration versus time curves for on line and laboratory measurements of radioactivity concentrations are shown in Figures 16 and 17 Maximum concentrations of the inert or weakly sorbing tracers are reached after about 2 weeks elapsed time Poor mixing in parts of the equipment such as in front of the stub surface and the pressure regulator cylinder is a likely cause for the late peaks 40 Observation of the relative concentrations at 13 days show an increase in sorption strength in the order Ca II lt IED lt Np V lt Cd IT lt Cs 1 lt Lu III lt Hf IV The trend generally follows the charge of the major species of the sorbing complexes Ca is non sorbing in the relatively saline water and weak sorption of iodine is observed Week sorption of iodine has been observed earlier at sp in e g
13. cabinet outside container 1 At two sampling occasions the pressure decreased below the set alarm level 28 bars once in the test section and once in the guard section The pressure needed to be re established by the pressure regulator but the power to the pressure regulator was disconnected by an automatic function in the PLC InTouch system as long as the pressure was below the alarm level Therefore the power to the pressure regulator could not be turned on again before the pressure was raised above the alarm level or possible if the alarm level would be adjusted temporarily to a level below the actual pressure The situation was solved both times by pressurising the system with the shortcut available to the guard section However this automatic function should be redesigned so that this situation can be avoided since the pressure regulator is much faster to increase the pressure than manual valve operations with the shortcut to the guard section 33 3 2 3 Valve operations in the circulation systems The circulation systems consist of a number of valves and attached units and the space in the glove box is densely packed with equipment It has been noted during the tests that the use of pre planned checklists and instructions is beneficial to minimise the risk for practical mistakes in different operations Check lists should be revised for the start of the long term diffusion experiment 3 3 Chemical speciation of tracers 3 3 1 Groundwa
14. diagram of the 6 port valves used for connections of equipment to the circulation line bottom Figure 5 Inert gas glove box for all circulation equipment excluding the pressure regulator which is contained within a separate inert gas box Figure 6 Inert gas box for the pressure regulator piston The pressure regulators consists of a step motor lower picture which operates a piston in a PEEK mantled cylinder upper picture The motor is controlled by a separate electronic unit The desired difference pressure between the test section KA3065A03 1 and the reference section first guard section KA3065A03 2 is set in the control unit 2 1 3 On line monitoring equipment in KA3065A03 1 ySpectrometry The radioactivity concentration in the test section groundwater is measured on line by an HPGe detector ORTEC relative efficiency 12 The detector is electrically cooled XCooler ORTEC A digital multi channel analyser DigiDart ORTEC is connected to the LTDEI computer through an USB interface In order to avoid ground loop disturbances a fibre optic converter OPTICIS optical USB extension cable M2 100 is placed between the DigiDart and the computer to create a galvanic isolation of the two units The spectra were collected and analysed using the software GammaVision 5 31 ORTEC The circulation tubing passes in front of the detector through a loop The loop is arranged so that the volume of the tubes exposed to the detecto
15. modifications are proposed to be done regarding automatic alarm functions and complementary electrical control in the system Rearrangement of the placement of the electrochemical flow cell in the glove box is also proposed in order to improve the practical work in the glove box and to reduce disturbances in the measurements Furthermore the experiment container needs cooling in order to reduce the temperature from 30 to 20 degrees C No tracers were detected in the guard section which indicates that the test section is tight towards the guard section 56 5 Future perspectives for a long term diffusion experiment A summary is given below of some points that should be considered in the planning of a long term diffusion experiment regarding experimental and technical conditions at the LTDE site The actions should be planned with consideration of the duration of a future experiment e Experimental conditions O Redox potential Since it has not yet been demonstrated that very low redox potentials may be reached at LTDE it is also unclear whether redox sensitive tracers can be obtained in their reduced forms in a future experiment However the strong interactions of HV metals with surfaces may affect the actual redox potential at which the reduced form is obtained We therefore recommend that scooping calculations addressing sorption reactions are done for IV elements for the present experimental conditions The results can then be a bas
16. not be performed in these structures during the forthcoming long term experiment The redox potential was slowly decreasing during the experiment but still positive Thus low negative redox potentials have not been obtained in the test section during the test period with nitrogen flushing of the inert gas boxes The redox potentials in the test section may be affected by mineral oxidations that occurred during the time that the borehole was open prior to the borehole installations Consequently more circulation time with a closed system may be needed to obtain reducing conditions The tracer production injection and sampling procedures that were developed were functional and more than 95 of the tracers in the stock solutions were injected About 2 weeks of circulation time were needed to obtain good mixing constant concentration for the inert and weakly sorbing tracers The slow mixing is likely caused by the existence of zones of relatively stagnant groundwater within the circulation system such as in front of the stub surface and in the pressure regulator cylinder The mixing behaviour in the test section is of minor importance for a sorption diffusion test that will last for several months or more However the use of the KA3065A03 borehole for short term tests hours to days is not recommended since the slow mixing complicates the evaluation in such a case 55 The equipment tests show that the systems generally worked as expected Some
17. results from the tracer experiment indicate that sufficient mixing of the tracer solution s in the test section will be obtained for a long term diffusion experiment as planned Short time experiments with duration of hours to days are however unsuitable with the present borehole configuration The duration of the functionality test was four weeks pH and redox potentials were continuously monitored with an electrochemical flow cell developed for measurements at high pressures Furthermore continuous pressure monitoring and additional sampling and analysis for tracers in the first guard section particles microbes radon sorption of tracers on tubing and groundwater chemical composition was done The results are shown and discussed in the report Sammanfattning Inom ramen f r LTDE projektet in situ studier av diffusions och sorptionsprocesser har funktionalitetsprovning med kortlivade radionuklider genomf rts Rapporten beskriver utf rande och resultat f r funktionalitetstesterna De huvudsakliga syftena med provningen var att prova injicerings och provtagningsprocedurer samt att unders ka funktionaliteten f r enskilda system s som cirkulationsutrustning tryckregulator olika givare on line m tningar och larmfunktioner Generellt sett fungerade alla system som f rv ntat N gra mindre justeringar och f r ndringar f resl s f r att f rb ttra vissa funktioner f re ett framtida l ngtidsf rs k ven injicering och provtag
18. unexpected indications of sorption of I I in the total experiment illustrates the difficulties of using I I as a non sorptive tracer a problem reviewed by e g Behrens 1982 The Cd II tracer is almost completely adsorbed in the cation exchanger Although the chemical speciation calculation below indicates an existence of chloride complexes it is obvious that the binding to the cation exchanger is strong enough to compete out the complexation or that the chloride complexes are adsorbed in the cation exchanger The large amount of adsorption of Cd in the anion exchanger is more difficult to explain One could speculate of the possibility of Cd forming surface complexes in the anion exchanger with the chloride loaded on the anion exchanger No solid proof for this theory can however be delivered 35 Np V is not to any significant amount adsorbed in the anion exchanger which is in line with the expected species NpO of that compound However it is somewhat unexpected that not more than 55 of the Np V is adsorbed in the cation exchanger A possible explanation to this is that the competition from naturally present high concentrations of cations in the groundwater e g Na and Ca and that the selectivity for monovalent NpO binding to the cation exchanger is not high enough to allow a full adsorption No result was obtained for Hf IV This was because the concentration had already decreased to very low amount and that no
19. used to complete the LTDE borehole installation KA3065A03 slimhole 16 2 1 2 Circulation equipment in KA3065A03 1 All circulation equipment such as pump flow meter and on line measurement of radioactivity and electrochemical flow cell are placed in inert gas boxes The boxes are flushed with nitrogen in order to reduce the oxygen content in the test section groundwater A schematic diagram of the circulation set up is shown in Figure 4 Pictures of the inert gas boxes are shown in Figures 5 and 6 All equipment is attached to 6 port valves in PEEK Upchurch Scientific Injection Valve V 540 as shown in Figure 4 The flow can be directed through the external unit attached to ports 1 and 4 or 1t can be bypassed to the next valve according to Figure 4 When the valve is in the bypass position the external units can be flushed using water from the first guard section The flushing is done through ports 2 and 3 in order to fill up and pressurise the unit with groundwater prior to connecting it to the circulation A Pump G Dose rate meter Stub P Stub 36 mm B Filter H Spectrometry upper lower hole C Flow meter I Pressure regulator D Electrochemical cell J Base stock injection E Sampling K Acidic stock injection F Circuit to 1st guard Load Inject Figure 4 Schematic diagram of the circulation set up during the tests top and connection
20. valve 15 is outlined The same is valid for loading of the injection loop joined to valve 14 A syringe was joined to port 2 and a short tube was joined to port 3 of the injection valves The tube had a length sufficient to reach down to the bottom of the glass vessel containing the stock solution When the injection valve is in its LOAD position ports 1 and 2 are connected as well as ports 3 and 4 This makes it possible with the help of the syringe to suck an aqueous solution guard water or stock solution into the loop The tubing loop was filled in three steps as follows see also Figure B 1 1 Asa first step the short tube was immersed in a beaker with guard water Approximately 3 4 ml was sucked into the syringe injection loop tube set up 2 Next the tube was transferred to the glass vessel and immersed in the stock solution The vessel was tilted to ensure that almost all of the stock solution was sucked into the tubing loop 3 When almost all of the stock solution was sucked into the set up a small amount of guard water was added to the vessel Suction with the syringe continued until small droplets of water could be seen in the inlet of the syringe indicating the syringe injection loop tube set up was filled with solution Thereafter the shut off valves were closed 67 LEE E E E 4 Stock Guard solution water bottle bottle Figure B 1 Drawing of equipment set up for controlled transfer of the stock solutio
21. was separated from the batch approximately 4 days after the neutron irradiation was finished Based on calculation using the mentioned values in some cases rather uncertain an amount of 36 MBq should thus be present at the injection time for the in situ experiment Preparation The irradiated BaCOx s was dissolved in 25 ml concentrated HCl Thereafter Na3SO4 was added to the solution to obtain a 10 excess of SO4 vs Ba The formed precipitation was allowed to undergo sedimentation thereafter as much solution as possible was extracted by a syringe and passed through a 20 nm filter To investigate the presence of any impurities in the solution the extracted solution was measured by y spectrometry The y spectrum and the corresponding activities of impurity isotopes in the solution are given in Figure A 1 and Table A 1 respectively An interesting observation is that only 160 Bq of Ba 131 is measured in the stock solution Based on calculations of the produced amount of 52 MBq it is estimated that gt 99 9998 of the Ba is precipitated by the sulphate precipitation This indicates a total chemical concentration of Ba in the stock solution 100 ug l 61 Table A 1 Isotopes identified by y spectrometry in the Cs stock solution Identified t d isotope Bq Activity Possible production reactions Isotopes obtained by irradiation of Ba Ba 131 11 5 160 Ba n gt Ba Cs 129 1 33 60 Ba n n gt Ba decay gt
22. 04 pre tests including hydraulic testing flow logging interference and pressure build up tests and non radioactive tracer tests dilution test and leakage testing have been performed Wass 2005 Installation and installation tests of the experimental set up at LTDE have been finalised during 2005 according to the SKB internal document AP TD F79 01 49 v 3 A schematic diagram of the experimental system for monitoring and sampling solutions from the test section and the inner guard section is given in Figure 2 This report describes a functionality test with short lived radionuclides that was performed during September to October 2005 according to AP TD F79 05 003 SKB internal document This test is a final preparation for forthcoming tests with more long lived radionuclides at the LTDE site Long Term Diffusion Experiment LTDE Experimental set up Tunnel in sp HRL at a depth of 410 m Borehole KA3065A03 1 A Test section fracture stub A Test section slim hole I 300 mm gt 3uard section Pressure 4 Pump Flow Sampling Valve gt regulation Natural meter unite P ref electronics fracture i A TNE 3 NR Totaliength 5 Pressure Dose rate coo P test 18 m 18 7 m gt 9 2 m meter meter oe I L Glove box with N gas 1 I nr nr A TEN E di oe ES lt
23. 2004 SKB contracted laboratories 2005 11 2005 09 2005 09 2004 01 OKG SKB SKB SKB Test section Test section Guard section Test section after injection before injection Cl 8 700 5920 6150 7 020 ppm S04 900 409 940 417 ppm Mg 50 46 45 42 ppm K 10 11 11 12 ppm Ca 2 170 1870 1880 2 030 ppm Na 2 660 1900 1900 2070 ppm pH 7 5 7 3 34 3 3 2 Speciation of tracers by ion exchange resins As a part of the effort obtaining speciation information concerning the tracers in the groundwater ion exchange studies were performed Two ion exchangers were prepared one containing 1 ml strongly basic anion exchanger Amberlite 16 50 mesh and the other containing 1 ml strongly acidic cation exchanger Dowex 50W x4 sodium form During the sampling first 5ml was slowly 1 droplet per 5 seconds passed through the anion exchanger 1 e taking the groundwater directly from the sampling valve to the ion exchanger The eluated water was collected in a scintillation vial and was later measured for its tracer content y spectrometry and Cs analysis according to the procedures described in section 2 3 4 After that the mentioned procedure was repeated for sampling through the cation exchanger Directly before the sampling through the ion exchangers a regular sampling had been performed The results of the ion exchange speciation is presented in Table 4 and are given as concentration decrease of the tracers in the eluates from the a
24. 4E 4 Ba 12 75d f y Ba l B 2 5 Sum 23 060 Radiotoxicity classed A 2 4E 4 B 102 C 3 9E4 1 2 3 4 The non injected part of the stock solution had an activity below the minimum detectable concentration at the time of measurement Instead the non injected part is calculated based on the average of the radionuclides that could be measured with enough accuracy Calculated value based on neutron absorption cross section and the isotope enrichment of Ca in the Ca target No calibration source available Total amount estimated from irradiation calculations Calculated value based on neutron absorption cross sections for U 23 2 3 Performance of functionality test with radioactive tracers One of the objectives of the functionality test with short lived radionuclides were to test injection and sampling procedures and the functionality of the entire system 1 e circulation equipment on line measurement with HPGe detector and environmental monitoring The performance of the test with radioactive short lived tracers is described below Standard procedures for preparation of stock solutions and calibration of detectors are not discussed in detail 2 3 1 Preparation of stock solutions Stock solutions comprising the short lived tracers were prepared at Baslab Clab SKB Two neutron irradiated quartz glass ampoules had been prepared with adequate amounts of targets salts and sent in advance to the Institute for E
25. HREEOC Parkhurst and Appelo 1999 Lu and Hf In addition to the above mentioned speciation calculations preliminary speciation calculations for Lu and Hf were performed In these calculations the LLNL database LLNL 2005 was used together with PHREEQC Parkhurst and Appelo 1999 The LLNL database is accompanying the PHREEQC Version 2 12 1 November 16 2005 Charlton and Parkhurst 2002 package available from USGS The tracer concentrations used in the calculations for Hf and Lu was taken from Table 4 The results for Lu indicate the following dominating species LuCO3 68 and Lu 20 Further the result indicates presence of the species Lu CO3 2 5 that to some extent might explain the loss of Lu in the anion exchanger cf Table 4 According to the preliminary results obtained for Hf the dominating species was Hf OH s 100 which might be doubtful since only three species were listed in the database Hf OH Hf and Hf OH The Hf OH s complex would also be expected to be non sorbing However if the sorption or surface complexation of Hf IV is stronger than the formation of the aqueous Hf OH s complex sorption can still occur since the equilibria then would be shifted towards the surface reactions 3 3 4 Radon sampling and analysis In order to estimate the radon concentration in the groundwater a 5 ml water sample was taken The sample was directly transferred from the sampling valve to a vial with 15 ml U
26. Rb ug l 37 6 Y ug l 0 291 Zr ug l 3 6 Sb ug l 0 498 Cs ug l 5 94 Hf ug l 0 835 TI ug l lt 0 05 U ug l 0 274 Th ug l lt 0 2 Br ug l 42500 ug l 115 CI mg l 5923 S04 mg l 409 S04 S mg l 137 75 APPENDIX E Chemical analysis of KA3065A03 2 sample 2005 09 15 ELEMENT SAMPLE KA3065A03 2 2005 09 15 LTDEGuard sect Ca mg l 1880 Fe mg l lt 0 004 K mg l 10 9 Mg mg l 45 4 Na mg l 1900 S mg l 132 Si mg l 5 6 Al ug l 4 13 Ba ug l 83 2 Cd ug l 0 163 Co ug l 0 194 Cr ug l 0 225 Cu ug l 1 69 Li ug l 1340 Mn ug l 279 Mo ug l 69 Ni ug l 25 7 P ug l lt 40 Pb ug l lt 0 3 Sr ug l 33600 V ug l 0 0573 Zn ug l 8 75 La ug l 0 0702 Ce ug l lt 0 05 Pr ug l lt 0 05 Nd ug l lt 0 05 Sm ug l lt 0 05 Eu ug l lt 0 05 Gd ug l lt 0 05 Tb ug l lt 0 05 Dy ug l lt 0 05 Ho ug l lt 0 05 Er ug l lt 0 05 Tm ug l lt 0 05 Yb ug l lt 0 05 Lu ug l lt 0 05 Sc ug l lt 0 5 Rb ug l 38 1 Y ug l 0 246 Zr ug l 2 41 Sb ug l 0 398 Cs ug l 3 67 Hf ug l 0 601 TI ug l lt 0 05 U ug l 0 278 Th ug l lt 0 2 Br ug l 42700 ug l 243 CI mg l 6152 S04 mg l 943 SO4 S mg l 314 77
27. The reason for this behaviour is likely due to responses through the rubber cylinder sealing at the stub or from penetrating tubing 1 e a mechanical disturbance rather than a hydraulic The pressure in the test section was restored quickly by the pressure regulator after sampling and injections as can be seen in Figure 22 49 KA3065A03 en KA3065A03 1 KA3065A03 2 kPa kPa 3700 i t ae kio ot p o M 3600 ro e 8 a e amp e i 3500 3400 3300 3200 3100 3000 23 50 55 00 00 5 10 15 20 25 30 35 40 45 50 55 01 00 5 10 15 20 START 05 09 15 23 50 00 INTERVAL All readings STOP 05 09 16 01 20 00 KA3065A03 ASPO HRL KA3065A03 1 KA3065A03 2 kPa kPa 3680 3660 3640 3620 3600 3580 3560 3540 50 00 30 51 00 30 52 00 30 53 00 30 54 00 30 55 00 30 56 00 30 57 00 30 58 00 30 59 00 30 00 00 START 05 09 15 23 50 00 INTERVAL All readings STOP 05 09 16 00 00 00 Figure 22 Pressure in test red circles and guard green plus sections in borehole KA3065A03 during injection and sampling The top figure shows injections and two samplings in the interval 2005 09 15 23 50 to 2005 09 16 01 20 The bottom figure shows the injection period 2005 09 15 23 50 to 00 00 in detail Note that the y scale is from 3540 to 3680 kPa A water sample is taken from 52 30 to 54 40 the first injection is done at 55 10 and the second injection at 56 10 50 3 8 Environmental monitoring Guard sectio
28. able 8 Equipment that need to be manually restarted after a power interruption at LTDE RNI instruments HPGe detector Circulation pumps test section guard section pilot borehole section Pressure regulator 52 3 9 3 Alarm system The alarms were coupled to the alpha system and tested with positive results 2005 09 08 Furthermore alarms have been triggered during the test period by testing of the diesel backup generator 2005 09 22 communication loss with the LTDE2 computer 2005 11 26 and by work sampling etc in the circulation system without prior blocking of alarm groups 2005 11 24 The control room at Clab have had access to the LTDE TRUE completion on call duty list and alarm instructions supplied by the project 3 9 4 Circulation equipment tightness test A continuous small drift in the position of the pressure regulating piston was observed in the beginning of October The drift was about 0 4 mm per day thus indicating a leakage of about 300 ul per day Visual inspections of valves and fittings in the inert gas boxes have not revealed the source of the leakage The relatively high temperature and dry nitrogen atmosphere leads to a fast evaporation of possible droplets Salt depositions have not either been observed which could indicate the leakage position A test was performed to confirm that the leakage is within the circulation equipment in container 1 The valves to the borehole were closed and a re coupling o
29. ansson H Andersson P Hansson K and Winberg A 1999 Test Plan for the Long Term Diffusion Experiment Swedish Nuclear Fuel and Waste Management Company SKB IPR 99 36 Byeg rd J Rameb ck H and Widestrand H 2002 TRUE 1 Continuation project Use of radon concentrations for estimation of fracture apertures Part 1 Some method developments preliminary measurements and laboratory experiments Swedish Nuclear Fuel and Waste Management Company SKB IPR 02 68 Byeg rd J Nordqvist R and Widestrand H 2004 Investigation of the possibility of using single well in situ sorption measurements of retention parameters in the site investigations Swedish Nuclear Fuel and Waste Management Company SKB PIR 04 16 Byeg rd J and Tullborg E L 2006 TRUE BS Continuation batch sorption experiments on rim zone material report in progress Swedish Nuclear Fuel and Waste Management Company Carbol P and Engkvist I 1997 Compilation of radionuclide sorption coefficients for performance assessment Swedish Nuclear Fuel and Waste Management Company SKB R 97 13 Charlton S R and Parkhurst D L 2002 PhreegcI A graphical user interface to the geochemical model PHREEQC U S Geological Survey Fact Sheet FS 031 02 2 p LLNL 2005 linl dat 2005 02 02 Data are from thermo com V8 R6 230 prepared by Jim Johnson at Lawrence Livermore National Laboratory in Geochemist s Workbench format Converted to Phreegc format by Greg
30. c2 tdb Reference thermodynamic data except for Technetium M Yui et al JNC Thermodynamic Database for Performance Assessment of High level Radioactive Waste Disposal System JNC Technical Report JNC TN 8400 99 070 For Technetium Rard J A et al 1999 Chemical Thermodynamics of Technetium OECD Nuclear Energy Agency Amsterdam North Holland 60 APPENDIX A Separation and measurement of the Cs tracer Introduction The Cs tracer offers some promising properties for use in in situ experiments It has a comparatively short half life 9 69 days which makes it advantageous in this type of experiment where one wants the tracer to have decayed within some months The tracer can also be produced with very high specific activity which allows uses in very high radioactive content without any particular increase of the chemical concentration The major disadvantage is that the tracer lacks measurable y radiation which makes the tracer somewhat more difficult to detect and quantify Production The Cs tracer used in this functionality test was produced by neutron irradiation 5 days of 2 25g BaCOx s 99 999 purity Aldrich at IFE Norway Approximate neutron flux was estimated to 1E13 n s cm The production occurs by neutron capture of the stable isotope Ba 130 0 106 of natural Ba which then forms Ba 131 which decays with a half life of 11 5 d to Cs The cross section for neutron capture of Ba 130 is 5 5 b The Cs tracer
31. cal for sp groundwaters 7 3 and 7 5 but the flow cell measurements indicate stable pH at 6 5 It can be questioned which is the correct measurement or if both methods are correct Possibly sampling may cause changes in the sample due to contact with air and degassing which could affect the pH values of the samples However the effects are usually not in this magnitude Measurements in deep boreholes down to 900 m in depth have shown that the difference between pH measured on line in the borehole and pH measured on surface is less than 0 5 units Wacker et al 2004 Typical pH values obtained from measurements in deep boreholes range between 7 and 8 5 The entire system seems to be sensitive to other activities in the glove box which can be observed as correlated peaks in the plots The discontinuities in the plots are due to calibration of the electrodes August 25 installation works at the test site and flushing of the section with water from the guard section September 6 and 7 A possible disturbance is static electrical fields which is often observed by adhesion of plastic bags papers etc onto the gloves in the box There is a possibility that the measurement system is affected by other power sources for example the circulation pump However no electrical disturbances from the pump motor or electrical cables were observed in a previous workbench test A new position of the flow cell at the back of the box may reduce such distu
32. cted acidic stock solution Fig 20 7 5 Ph o 7 Ir 65 o o o o 0 0 y o o o o o o o o o o o o o 6 H o 55 L L L 00 30 40 50 Start 2005 09 16 00 28 06 hour min Figure 20 pH measurement during the time of injection 3 7 Pressure monitoring and control All isolated borehole sections involved in the LTDE project are connected to the Hydro Monitoring System HMS for pressure monitoring through the PLC In Figure 21a and 21b an overview of the pressure in some of the LTDE borehole sections is presented The experimental hydraulic conditions were stable according to monitoring of pressure apart from short pressure disturbances Most of the disturbances seen particularly in the test and guard sections in KA3065A03 are due to injection and sampling occasions in the borehole One exception is the drawdown in the end of October i e after the official termination of the functionality test and is seen in all sections This is caused by the re instrumentation in the TRUE 1 boreholes KXTT3 and KXTT4 with the largest response about 200 kPa from KXTT4 The LTDE area is surrounded by two dominating structures NW 2 and NW 3 The TRUE 1 borehole sections are within structure NW 2 interpreted to intersect with structure NW 2 at the TRUE 1 site The test confirms the conclusion from the hydraulic pre tests Wass 2005 i e the NW 2 NW 3 and related structures are of vital importance for the hydraulic pressure res
33. d probably have been 2 3 orders of magnitude lower In the calculations NpO2 am was found to be oversaturated which could be explained by the high concentration of Np One calculation at 100 mV and with an Np concentration of 1 10 M NpO am was found to be undersaturated 36 Distribution of Np species as a function of Eh GW from KA3065A03 040121 100 oo Np OH 4 ME HE a a m NpO2 80 z A NpO2CI NpO2S04 60 x NpO2 C03 e 40 20 a i Lat Bo b b 600 400 200 0 200 400 600 Eh mV Figure 13 Geochemical speciation calculations for Np with the use of PHREEOC Parkhurst and Appelo 1999 The purpose of the speciation calculations for Cd was to investigate to what extent this tracer formed complexes with chlorine The Cd concentration in the calculations was set to the same as the experimental concentration i e 4 10 M The preliminary results indicate that CdCl 60 is the dominating species followed by CdCl 24 and Cd 12 See also Fig 14 According to the calculations the high chloride concentration make chloride complexes to effectively dominate over other complexes 37 Distribution of Cd in GW from KA3065A03 040121 70 60 50 40 4 30 20 10 0 T T T x N x ay o o sv T Se Name of species Figure 14 Geochemical speciation calculations for Cd with the use of P
34. d the water in the circulation loop This model approach is experimentally best addressed by determining A V from the dilution of a non sorbing tracer injected together with a sorbing tracer 2 4 2 One dimensional sorption diffusion model Ka and Kg For the case of loss of tracer from the aqueous phase caused by diffusion into the pores of the rock matrix surrounding the borehole and the stub surface a simplified model is used where the diffusion has been approximated to occur in a one dimensional mode Byeg rd et al 2004 With this model K m and Ka m kg the matrix sorption coefficient can be evaluated if the diffusion coefficient of the rock is known or estimated from e g independent measurements of the porosity The model is further described in Appendix C 27 2 5 Other equipment tests 2 5 1 In touch surveillance functionality tests The inputs and outputs to the PLC InTouch system were tested by 1 Test of reasonableness of input values note that this is not a calibration 2 Temporary adjustment of alarm levels in order to trigger alarms 3 Control of that the desired reaction of an alarm occurs e g stop of circulation pumps in case of a signal from a leak indicator etc 4 Control of that the alarms are displayed in the alarm list 2 5 2 Power Supply The functionality of the battery power supplies UPS units was tested in a separate test The diesel driven backup generator is tested monthly by Asp HRL s
35. down 2 A scintillation vial was placed under the tube 3 Valve 9 was switched into the INJECT position 4 The needle valve was opened with precaution A pressure drop less than 2 3 bar was desirable 5 The valve 9 was switched to LOAD position when approximately 12 15 ml had been withdrawn from the test section Thereafter the needle valve was set to fully open allowing remaining solution to drop into the sample To ensure that no solution will be left in the sampling equipment after each sampling a syringe was joined to port 2 on valve 9 and nitrogen was pressed with the aid of the syringe through port 2 and 1 to flush the needle valve and the tube Filtered samples In order to be able to take filtered water samples the tube was replaced by a filter To the filter a syringe was joined which was arranged to fit into a scintillation vial The same sampling procedure as outlined above was used 69 APPENDIX C One dimensional diffusion model slightly modified version of SKB PIR 04 16 A conceptual model for the transformation of a radial diffusion case into a simplified one dimensional case is described in Figure C 1 Aqueous phase Rock matrix Figure C I Conceptual model for the interpretation of a radial diffusion case into a one dimensional diffusion case The general one dimensional diffusion equation is expressed by 2 20 _ ec Ot Ox 1 In the present situation the interactio
36. ds to the total amount of tracer in the sheet after infinite experimental time Applying mass balance M can be expressed as 24 M l a 11 where Co is the initial concentration of tracer in the water phase Furthermore M can be expressed as M M M a0 Cy Cry 12 where Mo is the initial amount of tracer added to the system Maq is the amount of tracer in the water phase after an experimental time of t and Cag is the corresponding concentration of tracer in the water phase By inserting 11 and 12 into 10 and by rearranging the following expression is obtained a 1 En 2a D q t an 1 y zo om 13 0 r j j References Crank J 1975 The mathematics of diffusion one edition Oxford Univ press London 73 APPENDIX D Chemical analysis of KA3065A03 1 sample 2005 09 15 ELEMENT SAMPLE KA3065A03 1 2005 09 15 LTDE Test sect Ca mg l 1870 Fe mg l lt 0 004 K mg l 10 9 Mg mg l 45 9 Na mg l 1900 S mg l 130 Si mg l 5 71 Al ug l 11 2 Ba ug l 92 3 Cd ug l 0 2 Co ug l lt 0 05 Cr ug l 0 427 Cu ug l 2 98 Li ug l 1330 Mn ug l 59 4 Mo ug l 56 3 Ni ug l 6 06 R ug l lt 40 Pb ug l 0 682 Sr ug l 33800 V ug l 0 0671 Zn ug l 47 5 La ug l 0 566 Ce ug l 0 131 Pr ug l lt 0 05 Nd ug l lt 0 05 Sm ug l lt 0 05 Eu ug l lt 0 05 Gd ug l lt 0 05 Tb ug l lt 0 05 Dy ug l lt 0 05 Ho ug l lt 0 05 Er ug l lt 0 05 Tm ug l lt 0 05 Yb ug l lt 0 05 Lu ug l lt 0 05 Sc ug l lt 0 5
37. e for decision of tracer selection in a future experiment at the site We also recommend that circulation of the test section with redox monitoring and nitrogen flushing of the inert gas boxes are continued to allow for maximum decrease in redox potential Non sorbing tracers lodine showed a weak sorption with time in the functionality test and is therefore not a preferred tracer in a future experiment The selection of an inert tracer that can be analysed in the rock material after at least a year excludes some often used inert tracers Tritiated water cannot be used for rock analysis due to evaporation during handling bromide tracers are too short lived color dye tracers and metal complexes are undesired due to risk of complexation of the other metal tracers with high charges Thus Cl is the only reasonable choice although it requires chemical separation procedures since it has no y emission that can be measured using y spectrometry Experiment time A minimum experiment time of 2 two 3 months is recommended with the regards to the mixing time e Technical conditions O High temperature in container 1 Increased cooling of container 1 is required in order to decrease the temperature to about 20 degrees C Electrochemical flow cell The flow cell position should be changed for practical reasons and in order to decrease disturbances from glove box work Further reduction of possible electrical magnetic disturbances may be considered
38. e is shown passing the GM probe several times after the injection The monitor showed a peak after less than 1 day elapsed time see Figure 12 but this was not the true time needed to obtain a good mixing of the section since the GM monitor measures the actual gamma emissions without time corrections for the decay It can be seen below in the concentration time curves of the tracers section 3 4 that approximately 2 weeks circulation time was needed to obtain peak values of all tracers the strongly sorbing tracers peak earlier than the inert tracers due to the concentration decrease caused by the sorption The reason for the slow mixing is likely the existence of poorly mixed zones within the system such as the volume in the pressure regulating cylinder the slimhole ends and large parts of the stub surface where only diffusion exchange of water and tracers can take part with the flowing water the water enters the stub section in the middle of the stub and leaves in a tube placed in the periphery The slow mixing in the test section is of minor importance for a sorption diffusion test that will last for several months or more However the use of the KA3065A03 borehole for short term tests hours to days such as those described in the In situ K report Byeg rd et al 2004 is not recommended since the slow mixing complicates the evaluation in such a case Effective dose rate test section 2005 09 15 23 55 2005 09 16 02 15 2 5E 06
39. e third sample after injection is withdrawn 12 00 Water sample no 1 is withdrawn from the guard section 13 40 The fourth sample after injection is withdrawn 050920 Speciation of test section sample by ion exchange resins 050920 051006 050920 051012 050922 050926 051012 051108 051124 25 Sampling of samples 5 to 10 in the test section Sampling of samples 2 to 6 in the guard section Short power cut to LTDE due to diesel generator test Alarms from RNI and level indicators due to absence of UPS supply for these channels Restart of control equipment RNI instruments circulation pump and computer LTDE2 Sampling from the test section through a filter Sampling from the test section for analysis of radon and final sample during the undisturbed test period 11 Plastic scintillation probe failure probe gives no pulse output Probe disconnected for reparation 051124 Additional test section sample 12 guard section sample 7 and sampling of pilot borehole Additional sample of test section water from pressure cylinder to be compared with sample 12 Calibration performed of pH and redox electrodes in the flow cell done in the glove box Sampling of tubes for radioactivity measurement and microbe analysis 30 Besides the events listed above a continuous logging of the RNI instruments were made as well as logging of data from the flow cell A daily control of the LTDE test site has also been performed either
40. erize the rock in the vicinity of KA3065A03 In the earlier versions of test design only the stub itself was planned to be used for the matrix diffusion study However to be able to study also the diffusion in non decompressed rock without open fractures a small diameter 36 mm borehole approximately one metre long has been drilled in the centre of the stub At the end of the experiment the rock volume subject to diffusion is planned to be over cored sectioned and analysed for tracer activity concentration The in situ experimentation is supported by various types of mineralogical geochemical and petrophysical analyses Winberg et al 2003 have described the geologic and geotechnical features of the rock matrix in the vicinity of the test area in detail Borehole imaging by BIPS Borehole Image Processing System and core logging in the two boreholes were used to correlate fractures in the two holes The correlation was substantiated by mineralogy and geochemical studies including stable isotopes Within the framework of collaboration between SKB and Ontario Power Generation s OPG Nuclear Waste Management Division supporting laboratory experiments on core samples from the LTDE borehole KA3065A03 are in progress at Atomic Energy of Canada Limited AECL Vilks et al 2005 The experimental programme consists of porosity measurements diffusion cell experiments radial diffusion experiments and permeability measurements During 20
41. ers for which the sorption is dominated by a cation exchange mechanism 2 Tracers for which the sorption is dominated by a surface complexation mechanism 22 3 Tracers that are dependent of an electrochemical reduction in order to reach the tetravalent state oxidation state IV which is considered to be very strongly sorbing The corresponding higher oxidation state for the respective tracer is thus considered to be weaker sorbing Consequently the sorbing tracers are divided into the subcategories B1 B2 and B3 Table 1 Summary of radionuclides used in the experiment Radionuclides given in italic style are by products or daughters in the production of the radionuclides aimed for primary use in the experiment i e the radionuclides in non italic style By products in radiotoxicity class B and C with a total radioactivity below 1 kBq have been omitted Iso t Decay Oxidation state Group Radio Injected activity tope mode toxicity class kBq Na 1496h B y Nail B1 C 10 Ca 454d B y Ca ll B1 C 97 TSc 3 35d By Se lll C 9 0 Ca 163d By Ca ll B 4 37 Cu 1237 pp Cu ll B2 G 6 0 edi 2 224 B y Cdill B2 C 193 Ca 44 8d By Cad il C 7 131 8 02 d Byy Wl A B 95 Cs 9 69 d E Y Cs I B1 C 3 6E4 Ba 11 5d Ey Ba 11 E 1 5 lu 671d B y Lu ill B2 C 1 7E3 IHF 4239d B y HKIV B2 C 14 SHE 70 0d Ey Hf IV C 1 9 pp 2 355d p y Np V Np IV B3 C 890 py 24E4y a Pu A 2
42. ever some additional tests and samplings were also done during November A list of the major events is presented in Table 2 29 Table 2 Log of main events during the LTDE pre test Date Time Event 050905 The power was cut while connecting up the new power supply with diesel aggregate backup During the power cut the UPS s were checked They kept on for 30 minutes The power system was restarted and some switching was made to supply equipment from the right socket 050908 09 The electronics of the RNI instruments checked OK 050913 Water sample for bacterial analyse from the test section is taken Calibration of HPGe on line detector The part of the test section loop that goes via the on line HPGe detector is connected to the circulation system on KA3065A03 1 050915 21 00 Prior to injection of the tracer solutions a water sample is taken from the guard section 23 53 Prior to injection of the tracer solutions a water sample is taken from the test section 23 55 Injection of the acid tracer solution starts Valve 15 in injection position 23 56 Injection of the basic tracer solution starts Valve 14 in injection position 050916 00 06 Injection of basic tracer solution finished Valve 15 in load position 00 10 Injection of acidic tracer solution finished Valve 14 in load position 00 35 The first sample after injection is withdrawn from the test section circulation loop 01 15 The second sample after injection is withdrawn 06 09 Th
43. f small volumes of water 12 ml was done for subsequent analysis at Baslab A detailed description of the sampling procedure is given in Appendix B 2 3 4 Measurements at Baslab HPGe The radioactivity concentrations of the y emitting radionuclides were measured using an HPGe detector ORTEC relative efficiency 35 1 to 10 ml of the samples was transferred to scintillation vials that were filled up with deionised water to obtain a 10 ml geometry Liquid scintillation The procedures used for the measurements of Cs are further described in Appendix A 2 3 5 Calibration of detectors Prior to the start of the on line measurements the on line detector was calibrated with a mixed radionuclide standard solution Amersham QCY44 The solution was sucked into a loop using a syringe The calibration measurements on the HPGe detectors were evaluated with the program package Gamma Vision 5 31 ORTEC which also was used to determine the efficiency of the detectors and for measurements and evaluation of sample spectra The HPGe detector at Baslab was calibrated with a QCY44 solution 10 ml scintillation vial geometry was used for calibration and sample measurements For the liquid scintillation measurements of Cs no standard solution was available Instead radioactivity concentration relative to the injected concentration was calculated C Co The total injected radioactivity of Cs was estimated based on an irradiation decay calcu
44. f the pressure transmitter was done in order to measure the pressure in the circulation equipment that was now isolated from the borehole The system outside of the borehole was pressurised to 3470 kPa 44 h later the pressure had decreased to 2890 kPa which indicated a leak in the valves fittings or equipment In the next step the pressure regulator was started and the piston position was monitored Again a drift of about 0 4 mm per day was observed Consequently the small leak is probably within the equipment in container 1 Further search to find the leakage should be done by repeating the pressure test for the different parts of the equipment 3 10 Other observations The temperature in the experiment container container 1 has been high about 30 to 32 C during the test period The temperature within the inert gas boxes were 2 to 5 degrees lower due to the electrical coolers The container is insulated and the mechanical ventilation is not sufficient to cool the heat generated by the equipment inside the container It is recommended to take measures in order to maintain a temperature of about 20 C in the container 53 4 Conclusions The functionality test with short lived radionuclides showed that concentration time curves based on sampling and on line measurements of the radioactivity in the test section can be produced with the present experimental set up The successively decreasing concentrations with time for the sorbing tracers
45. for remote observations of container 1 and the borehole Temperature sensors are monitoring the temperature at a number of different positions on the site Pressure monitors from all borehole sections and surrounding boreholes are located in a separate cabinet All monitoring equipment is connected to the InTouch monitoring and control software in the computer LTDE2 through a PLC interface in Container 2 Groups of transmitters in InTouch are connected to the alarm system Alpha at sp HRL which in turn is connected to Clab Central interim storage facility for spent nuclear fuel located near the Oskarshamn Nuclear Power Plant OKG control room for 24h monitoring 2 2 Tracers Both sorbing and non sorbing tracers were used in the experiment The radionuclides that were used are summarised in Table 1 The use of the different radionuclides aims at studying different retardation processes e g sorption and diffusion The radionuclides have been categorised in two groups after their primary usage A Non sorbing tracers 1 e tracers that are assumed to diffuse without retardation due to sorption onto mineral surfaces The inorganic anions Br and CI belong to this group B Sorbing tracers 1 e tracers that are retarded by adsorption onto mineral surfaces These tracers are aimed to estimate the impact of sorption on the penetration into the rock The proposed tracers can be divided into three different subcategories within this group 1 Trac
46. ical solution to this problem has been given by Crank 1975 The total concentration within the sheet C including both the pore water concentration and the mass sorbed on the rock at the distance x at a given diffusion time of t is given by the expression D gt Asa a co 22 00 I I C C 14 gt 2 fal 1 0 0 4 cosq 5 where Ca is the concentration in the sheet after infinite time and the q values are the non zero positive roots of tanq 0 q 6 and a is the ratio of the capacities of the rock and water phase defined as a Tee Kp o Furthermore the decrease of the concentration of tracer in the start cell C1 can be calculated according to D g t 2a 1 ef C m 2 C Cio V p I gt 8 l 0 0 4 where Cio corresponds to the initial concentration in the start cell 72 By applying mass balance C can be calculated according to a Ed I a le K p 9 However for the present functionality test the concentration profile within the rock will not be possible to measure Instead the decrease of the concentration in the water phase caused by diffusion and or sorption in the rock will be the only available experimental parameter that can be measured The analytical solution for calculating the total amount of tracer in the sheet M after a given experimental time t is expressed as M _ 2a 1 ar aL a De 2 2 M alt l 00 where M correspon
47. ing the decrease in counting rate versus time are presented in Figure A 2 treated sample and Figure A 3 non treated sample As expected for the treated sample the decrease in counting rate can almost perfectly be explained from the tabulated half life of ICs i e 9 69d However for the case of the non treated sample a systematic deviation of the measured and projected values can be seen which probably can be explained by interferences of other and more long lived radionuclides It can be observed that the deviation is most severe when including the high energy part of the spectrum Comparing the count rate in the low energy part of the spectrum i e channel 1 180 from the treated and non treated sample it can be estimated that the efficiency of the separation process is gt 90 Possible causes for obtaining this apparent non quantitative separation process are e Non quantitative adsorption of Cs on the ammonium phosphomolybdate caused by e g the presence of Cs in a colloidal phase in the groundwater sample e Non quantitative dissolution of the ammonium phosphomolybdate in the NaOH treatment e Adsorption of Cs in the syringe filter after the dissolution e Quenching caused by the dissolved ammonium phosphomolybdate giving a decreased counting rate Based on the observed background counting rate an estimation of the detection limit Currie 1968 to 50 Bq per liter can be done by application of this method However a q
48. lation 26 2 3 6 Environmental monitoring The effective dose rates at the fence and in container 1 were monitored using RNI instruments according to the description in 2 1 4 The test section KA3065A03 1 and the first guard section KA3065A03 2 were monitored as described in 2 1 3 and 2 1 4 in order to detect sudden decreases of radioactivity in the test section or slow increases of radioactivity in the guard section respectively Furthermore the first guard section which is in primary contact with the test section was manually sampled to check for leakage from the test section The pilot bore hole KA3065A02 3 was also sampled at the end of the experiment 2 4 Interpretation of tracer test 2 4 1 Simple batch surface sorption model Ka A simple batch sorption model is applied in which sorption is presumed to occur only on the easily available sorption sites on the borehole walls and the stub surface i e no diffusion into the pores of the crystalline rock is considered Application of the surface sorption concept the loss of tracer in the water phase can be described as Cy 1 C 1 K A V 1 where Co is the initial tracer concentration Cag is the tracer concentration after sorption equilibrium has been obtained K m is the surface sorption coefficient A m is the geometric surface of the borehole section and the stub surface and V m is the total volume of water phase 1 e both the water in borehole section an
49. ltima Gold AB liquid scintillation cocktail of special purpose for alpha beta discrimination counting The sample was measured at Baslab using the Wallac instrument The sample radon concentration at the time of sampling was 35 Bq L which 38 is low compared to typical values of fracture samples at sp typically 200 to 1000 Bd L see e g Byeg rd et al 2002 However the surface to volume ratio in KA3065A03 1 is much lower than in fractures 1 e that the radon is diluted more in the test section than in other boreholes The radon emanation outflow from the surfaces in the test section have been calculated based on the known surface areas volume and radon concentration It should be noted that this is a simplified approach a more correct approach should probably include matrix diffusion estimations for the migration of the produced radon The radon emanation is presented in Table 5 together with a comparison of other materials The result in the test section is relatively high compared to the other materials that were measured in the laboratory Compared to the laboratory measurement of fracture specific material the production rate in the in situ experiment is gt 60 times higher The large discrepancies can be seen as an indication that laboratory experiments for estimating radon emanation not fully mimic realistic conditions Since radon emanation is a process analogous to matrix diffusion the results of radon emanation can be useful
50. n Samples were withdrawn from the guard section in order to detect any potential leakage from the test section into the guard section The samples were measured at Baslab on the HPGe detector From the obtained y spectra no evidence for leakage could be observed for any of the tracers used The spectra were also analyzed for MDA values Minimum Detectable Activity The MDA values divided by the total amount of activity injected for I are presented in Table 7 I is the radionuclide that had the lowest detection limit The MDA values are time corrected The volume of the guard section is 10 L 1 L and the sample volumes measured with the HPGe detector was 10 ml Table 7 Detection limits for I that could be detected by sampling in the guard section in the event of leakage from the test section into the guard section The values are given as the minimum fraction of leaked radioactivity in the test section that could be detected in the guard section This can be regarded as a maximum leakage fraction based on the actual detection limits of the different samples Date of sample Nuclide Time corrected activity Total injected amount 2005 09 16 1 131 lt 6E 04 2005 09 20 1 131 lt 2E 03 2005 09 26 1 131 lt 1E 03 2005 10 12 1 131 lt 3E 02 The on line measurement of the guard loop showed a decreasing value with time during the experiment which first was believed to be caused by an equilibration of the radon content of the guard section H
51. n to the injection loop The three steps of filling the loop are described in the text above Thus the stock solution was now transferred to the injection loop ready to be connected to the circulation equipment The only residual of the stock solutions were left in the vessels and could easily be returned to Baslab and be sampled and measured to determine the non injected amount of radioactivity Injection The injection was done by switching the valve to the INJECTION position connecting ports 1 and 6 as well as ports 4 and 5 The stock solution in the injection loop was then transferred into the circulation loop as a plug flow pulse It was desired that a plug flow within the tubing should be obtained until the stock solutions would reach the experimental test section in which mixing would occur and the two solutions would be pH equilibrated A photo of the equipment set up is shown in Figure B 2 68 Injection loop Injection valve 15 Injection valve 14 Stock solution 1 Stock acidic solution 2 alkaline Figure B 2 Injection valves photograph with tubes to stock solution bottles syringes and one injection loop visible behind the left syringe 2 Sampling procedure A short tube was connected to the outlet of the needle valve aimed to facilitate sampling in 20 ml plastic vials scintillation vials A description of the sampling procedure is outlined below 1 The circulation in the test section was shut
52. n can be regarded as diffusion from a stirred solution of limited volume into a plane sheet In order to benefit from the analytical solution of this case given by Crank 1975 a case where diffusion from both sides of the sheet occurs will be considered The sheet occupies the space lt x lt l while the solution is of limited extent and occupies the spaces l a lt x lt l and l lt x lt Ita The occupation length of the water phase a is set to a V A K 2 71 where V corresponds to the total volume used in the borehole experiment i e both the volume in the borehole section and the volume of the circulation equipment and A is the sum of the stub surface area and borehole wall area The length of the sheet has no influence of the rate of the loss of tracer in the water phase as long as the contribution of tracer diffusing from one side to the other can therefore be neglected The length can therefore be set arbitrarily and in this particular case has been set in order to obtain a tracer concentration in the middle of the sheet x 0 that is at least 10 times lower than the tracer concentration in surface layer of the sheet i e x or x The concentration of the solute in the solution is always uniform and is initially Co while the sheet initially is free from solute The following boundary conditions therefore apply C 0 pee zap 1l lt x lt l t 0 3 Ot Ox and PL ae x t gt 0 4 Ot Ox The analyt
53. n visas och diskuteras i rapporten Contents 2 2 2 3 2 4 2 5 3 1 3 2 3 3 3 4 Introduction Background Objectives Performance Equipment 2 1 1 Borehole KA3065A03 2 1 2 Circulation equipment in KA3065A03 1 2 1 3 On line monitoring equipment in KA3065A03 1 2 1 4 Other equipment Tracers Performance of functionality test with radioactive tracers 2 3 1 Preparation of stock solutions 2 3 2 Injections 2 3 3 Sampling 2 3 4 Measurements at Baslab 2 3 5 Calibration of detectors 2 3 6 Environmental monitoring Interpretation of tracer test 2 4 1 Simple batch surface sorption model Ka 2 4 2 One dimensional sorption diffusion model Ka and Ka Other equipment tests 2 5 1 In touch surveillance functionality tests 2 5 2 Power Supply 2 5 3 Alarm system Results and interpretation Overview of activities Procedures 3 2 1 Tracer injections 3 2 2 Samplings 3 2 3 Valve operations in the circulation systems Chemical speciation of tracers 3 3 1 Groundwater chemistry measurements 3 3 2 Speciation of tracers by ion exchange resins 3 3 3 Geochemical speciation calculations 3 3 4 Radon sampling and analysis 3 3 5 20 nm filtered sampling 3 3 6 Microbe analysis Tracer concentration measurements 3 4 1 Injected radioactivity 3 4 2 Tracer concentration time curves 3 4 3 Sorption on tubing 3 4 4 Evaluation of surface sorption Ka with simple batch sorption model 3 4 5 Evaluation of surface sorption Ka a
54. nctionality test with short lived radionuclides has been performed This report describes the performance and procedures of the functionality test together with the obtained results The main objectives of the test were to test injection and sampling procedures as well as to check the functionality of individual systems such as for example circulation equipment pressure regulator sensors on line measurements and alarms It could be concluded from the functionality test that all systems worked overall as expected Some minor adjustments and modifications are proposed to increase the functionality prior to a future long term test Also the injection and sampling procedures concerning the tracers functioned as planned Another objective of the test was to investigate 1f sorption in terms of decreasing tracer concentration in the test section could be monitored Both non sorbing and sorbing tracers were used The following trend could be observed Ca II lt I I lt Np V lt Cd IT lt Cs 1 lt Ludi lt Hf IV where no sorption of Ca II is observed and I I shows a weak sorption The sorption results are discussed in relation to speciation calculations for the different species Surface sorption coefficients and matrix sorption coefficients are evaluated for a batch sorption and a sorption diffusion model respectively However the sorption data presented in this report should be regarded as indicative rather than absolute Further the
55. nd matrix sorption Ka with one dimensional diffusion model 15 15 15 17 20 22 22 24 24 25 26 26 26 27 27 21 27 28 28 28 28 29 29 31 31 33 34 34 34 35 36 38 39 39 40 40 40 42 42 43 3 5 3 6 3 7 3 8 3 9 Test section volume estimations On line measurements of E and pH Pressure monitoring and control Environmental monitoring Other equipment tests 3 9 1 PLC InTouch control and monitoring unit 3 9 2 Power Supply 3 9 3 Alarm system 3 9 4 Circulation equipment tightness test 3 10 Other observations 4 5 Conclusions Future perspectives for a long term diffusion experiment References Appendix A Separation and measurement of the Cs tracer Appendix B Detailed description of injection and sampling Appendix C One dimensional diffusion model slightly modified version of SKB PIR 04 16 Appendix D Chemical analysis of KA3065A03 1 sample 2005 09 15 Appendix E Chemical analysis of KA3065A03 2 sample 2005 09 15 43 44 46 51 52 52 52 53 53 53 55 57 59 61 67 71 75 77 1 Introduction 1 1 Background Transport of radionuclides in rock fractures is presently studied within the TRUE experimental programme To be able to study diffusion and sorption processes over longer time scales a long term diffusion experiment LTDE has been set up at sp Hard Rock Laboratory in Sweden The original experimental plan was laid out by Byeg rd et al 1999 Since then
56. nergy Technology IFE Kjeller Norway The irradiated ampoules delivered from IFE were 1 Irradiated salts for production of Na Ca Cu Br Ca Pl Ba BaCO isotope enriched in Ba was planned to be used Lu Hf and 2Np this solution was injected first 2 Irradiated BaCO of natural isotope composition for production of Cs second solution injected Solution 1 The contents of the ampoule was dissolved in an acidic aqueous solution and moderately heated while stirred After cooling the solution was checked for its radioactivity content filtered and transferred to a glass bottle Next the solution was pH adjusted To avoid sorption phenomena on glass vessels and tube walls for sorbing tracers the solution was prepared in a weak acid solution of approximately pH 1 5 A small amount of a separate stock solution comprising I was transferred to a cation exchange resin and eluated with distilled water After control measurement an appropriate amount of the I solution was transferred to solution 1 The solution was then sampled to determine the final radioactivity content Solution 2 The preparation of the Cs stock solution is described in Appendix A The stock solution was filtered 0 45 um and transferred to a glass vessel As the amount of acid injected in solution 1 may exceed the buffer capacity of the test section site it had to be neutralized with a base NaOH which was added to solution 2 pH 12 5 The soluti
57. ningsprocedurer fungerade som planerat Ett annat syfte med provningen var att unders ka om sorption i form av minskande sp r mneskoncentration 1 testsektionen kunde m tas med utrustningen B de icke sorberande och sorberande sp r mnen anv ndes F ljande trend i sorptionsstyrka observerades Ca II lt I I lt Np V lt Cd lt Cs I lt Lud lt Hf IV dar ingen sorption av Ca II observerades och jod sorberade svagt Sorptionsresultaten diskuteras 1 relation till specieringsber kningar f r respektive grund mne Ytsorptions och matrissorptionskoefficienter utv rderades f r en enkel ytsorptionsmodell samt en endimensionell sorptions diffusionsmodell Sorptionsresultaten skall dock ses som indikativa och inte absoluta v rden Resultaten indikerar att tillr cklig omblandning av injicerade sp r mnesl sningar 1 testsektionen f s f r ett kommande l ngtidsf rs k Snabba experiment med en varaktighet av timmar till dagar r dock ol mpliga att genomf ra vid LTDE med nuvarande borrh lskonfigurering pga tiden att n fullst ndig omblandning Funktionalitetstesten varade i 4 veckor pH och redox potentialer m ttes kontinuerligt med en elektrokemisk fl descell som utvecklats f r m tningar vid h ga tryck Vidare s utf rdes kontinuerlig tryckmonitering och provtagning och analys av sp r mnen i guardvattnet partiklar mikrober radon sorption av sp r mnen p slangar samt kemisk analys av grundvattnet Resultate
58. nion and cation exchangers given in relation to the concentration in the non processed sample Regarding the results for the presumed cations the Cs I Ca II and Lu III interact as would be expected from a cationic form more or less completely sorbed in the cation exchanger and passing through the anion exchanger There are however some indications of losses of especially Lu II in the anionic exchanger which possibly could be caused by the existence of e g a negatively charged carbonate complex species cf section 3 3 3 Nevertheless the very different behaviour and also expected behaviour of the presumed cations in the cation exchanger and anion exchanger respectively should be regarded as a proof of none or very little existence of colloidal forms for these tracers The obtained result for the speciation of iodine is difficult to explain Not more than 56 of the I I is found to sorb on the anion exchanger However one should be aware of that the high concentrations of Cl together with the pre saturation of the anion exchanger with CI might act as an effective competitor for the sorption of T on the anion exchanger If there is not very much higher selectivity for T versus Cl this could be a possible explanation for that the I I is not completely adsorbed by the anion exchanger What is even more difficult to explain is the indication of adsorptive loss of I I in the cation exchanger 29 This observation together with the
59. nt experimental set up i e measurement of the decrease of tracer concentration in the test section volume 2 Performance 2 1 Equipment 2 1 1 Borehole KA3065A03 The experimental set up consists of a telescoped large diameter borehole KA3065A03 that intercepts a previously identified fracture The intersected part of the fracture is packed off using a special packer which seals around the developed core stub A solution with conservative and sorbing radioactive tracers can be injected and circulated in the isolated section A small diameter 36 mm borehole approximately one metre long has been drilled in the centre of the stub 300 mm section of the small diameter borehole is packed off for tracer circulation purposes Further the borehole outside the stub is packed off with mechanical and inflatable packers to avoid effects of the acting hydraulic gradient A schematic diagram of the packer system used to complete the LTDE test hole is shown in Figure 3 2 P amp 9 Up P O Inner guardsection Section Packer regulation Jy Piston pipe Hydraulic Mecanical Inner guard locking device packers Outer pipe packer section a zu I iS a oq z I Nr In Core stub Mecanical Dummy packer Guard sections Sealing Expander Outer seal and Packer packer expansiongear anchor device N a Figure 3 Schematic diagram of the packer system
60. o the right the decrease of counting rate versus the elapsed time is presented The dots represents the measured value and the line shows the projected decrease of the counting rate based on the tabulated half life of Cs 9 69 d References Byeg rd 2002 Tracer Retention Understanding Experiments Continued sampling and tracer measurement in the TRUE 1 experiment and the TRUE Block Scale experiment phase C SKB IPR 02 69 Swedish nuclear fuel and waste management company Stockholm Currie 1968 Limits for qualitative detection and quantitative determination Application to radiochemistry Anal Chem 40 586 593 1968 65 APPENDIX B Detailed description of injection and sampling 1 Injection procedure Transfer of stock solution to tubing loop The length of each loop was adjusted to in addition to the stock solution hold approximately 6 7 ml guard water The purpose of having guard water in the beginning and in the end of each loop was to minimize the loss of tracer solution at the transfer of the stock solution from the glass vessel to the tubing loop The two loops were joined to injection valve 14 and 15 respectively at ports 1 and 4 see Fig 4 and B 1 The injection valves 14 and 15 were placed in series 14 before 15 The injection loop joined to valve 14 comprised the alkaline stock solution while the acidic stock solution was joined to valve 15 In the following the procedure to load the injection loop joined to
61. on was then sampled to determine the final radioactivity content The two ready mixed stock solutions were then checked for external contamination cleared and transported as a radioactive transport to the LTDE test site according to the routines at OKG 24 2 3 2 Injections Principle for injection The first injection solution 1 was done in acidic solution in order to avoid precipitation of some tracers mainly Hf and Lu and to minimise sorption on equipment before the tracers reached the test section The second injection solution 2 contained an excess of base in order to neutralise the acidic first injection The principle for the injection was to inject the tracers as pulses with a plug flow and short but sufficient time spacing between the two injections The acidic pulse would thus reach the test section a short time before the basic pulse and the water would be pH equilibrated to a large extent by the mixing in the first passage of the pulses through the slimhole and stub sections If precipitation or strong sorption would occur immediately following neutralisation this procedure would at least make it occur mainly within the slimhole or stub sections A schematic picture of the serial pulse injections is shown in Figure 10 Solution 2 Solution 1 alkaline acidic Before injection gt gt 0O lt t lt 1 min 1 lt t lt 11 min Figure 10 Principle of injection procedure At time t 0 the tubing loo
62. on site or reading of files via computer connected to the SKB HRL net login In this last case the video cameras at the test site were used to read for example the position of the pressure regulator and the circulation flow in the test section 3 2 Procedures 3 2 1 Tracer injections Some of the radionuclides that were planned to be included in the tests according to the technical description Widestrand and Byegard 2005 were not actually used in the experiment for different reasons Tc was said to require a medical permit according to the supplier and could thus not be delivered Cu decayed to a large extent ty 12 7 h between the time from removal from the reactor to injection i e 4 days Br was not obtained in solution 1 as was planned the reason for this is not clear A possible explanation is that due to the nitrate media used the bromide was vaporised and driven off as Br gas in the drying stage of the preparation of the target Ba was produced in much lower quantities than originally calculated due to delivery from the supplier of the Ba isotope in a non soluble chemical form of probably BaSO instead of BaCO This made the dissolution of the salt difficult already in the first preparation of the ampoule prior to the irradiation Thus the ampoule contained very little or no Ba A small amount of the fission product Ba was produced from fission of U which only to a slight extent compensated the loss of Ba
63. or measurements under high pressure Pehkonen 2005a and b Calibrations are performed by circulation of calibration solutions pH 4 quinhydrone pH 7 quinhydrone and pH 10 Calculation of calibration constants and recalculation of measurement data given in mV is done manually Figure 9 Electrochemical flow cell used for on line measurements of pH and Eh 21 2 1 4 Other equipment Effective dose rate at fence and in container 1 The effective dose rate in units of uSv h at the fence towards the tunnel and in container 1 was monitored using RNI 10 SR instruments RNI AB The data were collected through a computer interface in the same way as described for the test section dose rate monitoring above Monitoring of radioactivity in the first guard section KA3065A03 2 The first guard section KA3065A03 2 have a circulation equipment placed in a cabinet outside of container 1 The radioactivity in the groundwater of the first guard section was monitored by a 1 inch plastic scintillator probe connected to a RNI instrument The probe was placed within a loop of the guard tubing in a separate lead shield The volume of the loop is approximately 85 ml Other equipment Leak indicators are placed inside the inert gas boxes on the floors of the containers and in the cabinet for the guard and pilot hole circulations equipment Difference pressure transmitters are monitoring the pressure in the inert gas boxes Three network cameras are used
64. ounting technique has to be applied for the measurement Since a cocktail of radionuclides were used in this experiment interferences from other radionuclides should be expected for a simple sample measurement using liquid scintillation technique Therefore a selective Cs separation is advantageous for a correct quantification of Cs In this experiment the following procedure for separation and measurement of Cs was applied A chemical separation procedure was used in which 1 ml sample was mixed with 9 ml 0 01M HCI followed by an addition of 10 mg of ammonium phosphomolybdate hydrate Aldrich This compound is known to be a very strong Cs trapper cf e g Byegard 2002 This mixture was thoroughly mixed and allowed to equilibrate for 1 hour and thereafter the slurry was passed through a 20 nm syringe filter After that 1 ml of IM NaOH was passed through the filter to dissolve the Ammonium phosphomolybdate hydrate and the solution was collected in a 20 ml plastic scintillation tube 15 ml of scintillation cocktail Emulsifier Safe Perkin Elmer were added and measurement was performed using a Wallac 1414 Guardian In order to estimate the efficiency of the separation procedure a comparative measurement was performed for an ammonium phosphomolybdate hydrate treated sample and an equivalent sample spiked without any treatment into a scintillation cocktail The spectrum obtained from the different measurements together with the graphs show
65. owever the probe finally stopped giving any pulse output so the results of the guard measurement may have been affected by a slow degradation of the probe function Pilot borehole KA3065A02 3 The pilot borehole groundwater sample of 2005 11 24 showed no content of I which was an expected result since no tracers were found in the first guard section either and the pilot borehole is further away with a larger dilution in case of a leakage Dose rate measurements at fence and in container 1 The dose rates at the fence and in container 1 were stable and slightly lower than 0 2 uSv h during the test period The contents of gamma emitting radionuclides in the stock solutions were quite low about 3 MBq which is why no significant increases in dose rates were obtained during this experiment 51 3 9 Other equipment tests 3 9 1 PLC InTouch control and monitoring unit The tests of the input and output channels showed that all channels except the oxygen monitor in container 1 worked properly A few channel cross couplings were discovered and corrected during the test 3 9 2 Power Supply During a planned interrupt in the power supply to the LTDE test site for change of power support the UPS functions were monitored The UPS units lasted for a minimum of 30 minutes This time is shorter than the system was originally designed for 2h but good enough in the new situation where the diesel backup generator should result in a power interru
66. p containing the acidic stock solution 1 is switched into the circulation and at time t 1 min the alkaline solution 2 is switched into the circulation The injection valves used were placed as the last equipment at the end of the circulation loop before the exiting outflow to the borehole sections see Figure 4 This was done in order to minimise the volume and to avoid mixing of the pulses with stagnant water before entering the borehole sections 25 Performance of injection At the LTDE test site the stock solutions were taken through the airlock into the glove box together with the injection loops The specific tube volumes had been determined in advance at Baslab The stock solutions were transferred to the injection loops with help of syringes A procedure was developed whereby the only residual of the stock solutions were left in the vessels and could easily be returned to Baslab for sampling and determination of the non injected amount of radioactivity A detailed description of the transfer and injection procedure is given in Appendix B The plan for injections was to first inject solution 1 and after one minute inject solution 2 in order to avoid mixing of the solutions in the tubing After an additional time of 10 minutes loop 2 was disconnected from the circulation and four minutes later loop 1 was disconnected from the circulation 2 3 3 Sampling In addition to the on line HPGe measurements of the circulation loop sampling o
67. peration without failures during the period April to November Prior to the start of the experiment the cylinder was filled up with groundwater by running the piston backwards to a position of about 100 mm maximum 500 mm in order to allow for outtake of sampling volumes during the tests and still to enable pressure regulation to lower pressures if needed More detailed plots over the pressure in the test and guard sections in borehole KA3065A03 during injection and sampling procedures are shown in Figure 22 The first injection acidic injection valve 15 was made at 23 55 and is not visible in the pressure plot The second injection basic injection valve 14 was made at 23 56 and the following drawdowns around 00 35 and 01 15 are sampling occasions The pressure dip at the second injection 23 56 was caused by compression of nitrogen gas trapped in the injection loop Prior to the injection a groundwater sample was taken approximately between 23 52 to 23 55 Short pressure responses in the first guard section KA3065A03 2 is recorded at several times in connection to pressure changes due to sampling or injections in the test section It can be seen in Figure 22 bottom that the response in the guard section appears both in the beginning and at the end of a drawdown in the test section It is observed as a pressure decrease following the opening of the test section and as a pressure build up when the pressure is restored by the piston movement
68. ponses in the LTDE boreholes and pumping drilling etc should not be performed in these structures during the forthcoming long term experiment 46 lt o MC71 K065A3a1 MC73 K065A3a2 MC83 K065A2 3 MC112 KA3067A2 MC96 KA3068A1 MC92 SA3045A2 LTDE LTDE LTDE LTDE LTDE kPa kPa kPa kPa kPa kPa 3700 3650 3600 E E 3550 bt A amp i 3500 5 E 3450 5 g 3400 E 3350 3300 3250 3200 09 14 19 24 29 10 04 9 14 19 24 29 11 03 8 13 18 23 month day START 05 09 14 00 00 00 INTERVAL All readings STOP 05 11 25 00 00 00 Figure 21a Pressure in some selected LTDE borehole sections during the period 2005 09 14 2005 11 25 See Figure 1 for borehole locations 47 u ao MC71 K065A3a1 MC73 K065A3a2 MC83 K065A2 3 MC112 KA3067A2 MC96 KA3068A1 MC92 SA3045A2 LTDE LTDE LTDE LTDE LTDE kPa kPa kPa kPa kPa kPa 3680 3660 a 3640 a 48 ee dl B 3620 he t r i 4 B 2 Sr y g B 8 3600 Si 9 fr A El Q BE de 3580 DF F 3560 Pr E B 09 14 19 24 29 10 04 9 14 19 24 29 11 03 8 13 18 23 month day START 05 09 14 00 00 00 INTERVAL All readings STOP 05 11 25 00 00 00 Figure 21b Pressure in some selected LTDE borehole sections during the period 2005 09 14 2005 11 25 Note that the y axis scale is magnified compared to Figure 21a See Figure 1 for borehole locations 48 The pressure regulator has been in stable o
69. pt of about 10 to 20 s However it was noted that some equipment is not supplied by the UPS units The level indicators and the RNI instruments are supplied by DC voltage without UPS backup Therefore the RNI instruments needs to be restarted even after a short power interrupt Some other units also need to be restarted in the event of a power interrupt to LTDE The HPGe detector also needs to be restarted since it has a non UPS backuped power supply The reason for this is that the power from the UPS units causes disturbances in the HPGe detection system possibly from ground loops The units that need to be restarted are shown in Table 8 The alarm will also be triggered from the level indicators and the RNI instruments during the start up of the diesel aggregate However the alarms cause automatic functions in the PLC InTouch to disconnect other equipment e g the pressure regulator and the circulation pump are switched off When power returns the alarms disappear but some of the switched off equipment needs to be manually restarted It is desired to install UPS backed up power supply to the level indicators and the RNI instruments prior to a long time experiment Further voltage monitoring after both earth faults breakers is desirable It may also be beneficial to install auxiliary contacts on the fuses in the distribution boxes Further the automatic functions should be invented and adjusted prior to a start of a long term experiment T
70. r is about 5 ml The distance between the detector window and the tube was approximately 1 5 cm A picture of the lead shield and parts of the detector is shown in Figure 7 Figure 7 Lead shield and parts of the HPGe detector used for on line radioactivity concentration measurements Test section effective dose rate The effective dose rate in a separate loop of the test section 35 ml volume was monitored using a GM probe connected to a RNI instrument RNI AB in a separate lead shield The RNI instrument has a data connection to the LTDE1 computer through a RS 232 interface The software RNICom is used to collect and display data from the instrument This monitoring is used to give alarm if a sudden decrease in the dose rate of the test section loop should occur as a result of a leakage in the test section A picture of the lead shield and the back part of the probe is shown in Figure 8 20 Figure 8 Lead shield and back part of the GM probe used for on line dose rate monitoring Electrochemical flow cell A flow cell and a measurement system have been developed for continuous measurements of pH and Eh at high pressures SKB internal document AP TD F63 03 45 Figure 9 shows the flow cell which is made entirely in PEEK The electrodes situated in the flow cell are two glass electrodes a platinum electrode Pt a gold electrode Au and a reference electrode Ag AgCl The pH and reference electrodes are specially designed f
71. r the reference electrode was found to be less than 10 mV which is an acceptable normal drift considering the time span At the time of the final calibration the redox potential had decreased from the initial 500 mV to 200 mV gold and 100 mV platinum and continued decreasing slowly However the first measurements after an exchange of test section groundwater and a final calibration indicates an increasing redox potential not shown in figure The relatively high redox potential at the termination of the measurement and the indication of increasing redox potential after the final calibration causes doubts regarding the possibility to reach low enough redox potentials for reduction of redox sensitive tracers in the test section Oxidation of minerals in the test section during previous exposure to oxygen could be one reason for the slow decrease of the redox potential The borehole was open and exposed to water in contact with air for a relatively long time months to a year between the drilling and the borehole installations The expected potential would be about 150 mV or lower based on previous measurements in deep boreholes Wacker et al 2004 which is far from the lowest observed potentials at 100 mV The pH was stabilising at 6 5 during the last weeks of the measurement One of the glass electrodes was found to be defect and it was excluded from the analysis It can be noted that the pH measurements on samples presented in Table 3 are typi
72. rbances If that does not help the flow cell may need a metal shielding 44 Ph o 7 5 F S T o Installation work 5 5 H 08 15 09 01 15 10 01 Start 2005 08 12 00 25 24 month day Figure 18 pH measurement in section KA3065403 1 2005 08 12 2005 10 12 The period marked by the arrow was affected by installation works The small peaks in the period after 2005 09 15 are correlated to activities in the glove box 800 2 Au hydrogen o Installation work 2 Pt hydrogen 600 u 400 f 2 Eh mV Flushing of hd test section with guard water 200 08 15 09 01 15 10 01 Start 2005 08 12 00 25 24 month day Figure 19 Redox measurement in section KA3065A03 1 2005 08 12 2005 10 12 The dips indicated by the vertical arrows were obtained after flushing of the test section with groundwater from the first guard section When flushing was discontinued and the test section groundwater was circulated only the redox potential increased again The Au electrode was very sensitive to activities in the glove box as can be seen by the many dips in the time period after injection 2005 09 15 The period marked by the horizontal arrow was affected by installation works 45 The radionuclide solution was injected September 15 A small decrease in pH was observed shortly after the injection which could be an effect of not obtaining a complete neutralisation of the firstly inje
73. show that sorption processes in the test section can be studied at the LTDE site Only a minor sorption on tubing could be measured for the most strongly sorbing tracer which indicates that the sorption occurs to a major extent on the stub and slimhole rock surfaces It is concluded that sampling and on line measurements complement each other and that both should be done in future experiments Observation of the relative concentrations at 2 weeks experimental time show an increase in sorption strength in the order Ca II lt I I lt Np V lt Cd IT lt Cs I lt Lu III lt Hf IV The trend generally follows the charge of the major species of the sorbing complexes Ca with its strong hydration shell is non sorbing in the relatively saline water and a weak sorption of iodine species is observed The reason for the weak sorption of iodine is not clear Speciation calculations for Cd Lu Np and Hf give a consistent picture of the observed concentration decreases in relation to the dominating species for the different elements Cs was relatively strongly sorbing in accordance with earlier field tests at sp The experimental conditions were stable according to monitoring of pressure and pH apart from short pressure disturbances due to sampling and injection The pressure regulator worked well The NW 2 NW 3 and related structures are of vital importance for the hydraulic pressure responses in the LTDE boreholes Pumping drilling etc should
74. t sufficient measuring time was available for the y spectrometry measurement of the ion exchange processed samples to obtain enough counting statistics for Hf Table 4 Speciation of tracers using ion exchange resins Tracer Concentration Sorbed in Sorbed in M cation anion exchanger exchanger I 1 Carrier free 29 56 Cs l 1E 8 nat 99 13 Ca ll 0 05 gt 98 lt 1 Cd Il 1E 7 94 71 Lu lll 2E 10 gt 91 25 Hf IV 2E 7 Not speciated Np V Carrier free 55 2 U 2E 7 3 3 3 Geochemical speciation calculations Cd and Np Preliminary geochemical speciation calculations regarding Np and Cd have been performed The program PHREEQC Parkhurst and Appelo 1999 was used in the calculations together with the database files from Yoshida and Shibata 1999 and Allison et al 1990 used for Np and Cd respectively In the calculations the groundwater composition from KA3065A03 dated 2004 01 21 was used The speciation calculations for Np aimed to see the distribution of the species as a function of the redox potential Eh The preliminary results can be seen in Fig 13 which indicate that Np V is the dominant oxidation state above 100 mV The Np V species are known to sorb very weakly Carbol and Engqvist 1997 and this may explain the high Np concentration observed in the present LTDE functionality test The concentration of Np in the calculations was 1uM This is a quite high figure a more realistic one shoul
75. taff 2 5 3 Alarm system The coupling of the alarms from the PLC InTouch system to the Alpha system was tested in combination with the test described in section 2 5 1 28 3 Results and interpretation 3 1 Overview of activities Selection and scooping calculations of possible radionuclides were finalised in early July 2005 A technical description Widestrand and Byeg rd 2005 of the experiment was accepted by SKB in the beginning of August Prior to the start of the experiment a number of activities were completed e purchase of radionuclides e remaining installations at the test site e experiment preparations e functionality test of equipment e development and test of sampling procedures e completion of on call duty lists and alarm instructions e radiation protection review by the OKG staff including marking of the test site to controlled area Radionuclides were delivered to OKG and transported to Baslab by internal transport at OKG The irradiated ampoules were transported from Kjeller Norway in a separate road transport conducted by IFE personnel Tracer stock solutions were prepared at Baslab and the injections were done on September 15 2005 Sampling and analysis was continued to October 12 after which the functionality test was officially terminated in order to let other work in the tunnel proceed work that potentially could cause pressure disturbances at LTDE were on hold during the functionality test How
76. ter chemistry measurements The groundwater samples taken in the test and guard sections directly before the injection 2005 09 15 were analysed by the SKB contracted laboratory The complete analysis results are presented in Appendix D and E A sample containing radionuclide tracers 2005 11 24 was analysed at OKG Nuclear Power Plant Chemistry Laboratory 02 The results are shown in Table 3 The results show an increased salinity in the test section groundwater after injection which partly can be explained by the Na Ca Cl and SO content of the stock solutions However the charge balance is about 8 negative for the 2005 11 sample This sample was measured using ion chromatography and the sample was diluted by a factor of 10 which cause an additional uncertainty in the Cl and SO values A calculation of the Na Ca Cl and SO concentration increase in the test section after injection was done based on the contents in the stock solutions The calculated concentration increases in the test section groundwater from the stock solution injections are 1200 ppm for Cl 800 ppm for Na 90 ppm for Ca and 90 ppm for SO Thus the concentration increase caused by the injection can only partly explain the high concentrations of the 2005 11 24 sample Table 3 Major components analysis of test section sample after injection sampled 2005 11 24 OKG laboratory test and guard section samples before injection 2005 09 15 and comparison with sampling January
77. the experimental concept has been modified to some extent and is currently being revised again A recent review by Peter Vilks AECL Canada gives a good overview of the developments and the present status of the project Vilks 2004 The main objectives of LTDE are e To investigate the magnitude and extent of diffusion in matrix rock from a natural fracture and in fresh un altered rock in situ under natural rock stress conditions and hydraulic pressure and groundwater chemical conditions e To obtain data on sorption properties and processes of individual radionuclides on natural fracture surfaces and internal surfaces in the matrix e To compare laboratory derived diffusion constants and sorption coefficients for the investigated rock fracture system with the sorption behavior observed in situ at natural conditions and to determine if laboratory scale sorption results are representative also for larger scales The LTDE site is located in the niche at tunnel section 3065 m at a depth of approximately 410 masl KA3065A03 is the experimental borehole and KA3065A02 has served as exploration pilot borehole to find a suitable target structure on which to perform the experiment see Figure 1 for borehole locations SA3045A Tunnel with i experimental Mis site NASA3067 p Y Expel Electronic container 3068A container Figure 1 Location of the LTDE experimental hole KA3065A03 and the pilot hole KA3065A02 used to help charact
78. tub surface and the borehole wall in the slimhole The data are presented in Table 6 below 42 3 4 5 Evaluation of surface sorption Ka and matrix sorption Kg with one dimensional diffusion model Surface sorption coefficients and matrix sorption coefficients were evaluated as described in section 2 4 2 and Appendix C The pore diffusivity was calculated using Archie s law based on an assumption of 0 5 rock matrix porosity and using water diffusivities for the different species Ka was the only fitting parameter and K was calculated based on Ky K ratios obtained from the TRUE BS project The fitting of the model was done to the concentration decrease at 28 days i e only one data point was modelled The results are therefore only indicative and should not be regarded as absolute values The data are presented in Table 6 Table 6 Preliminary sorption data from very basic evaluations of the functionality tests These data should be regarded as indicative and should be used with precaution before a deeper evaluation including modelling of the whole data sets is done Evaluation was done after 28 days Note that the diffusion model was fitted to the 28 day data point only i e that the whole data set was not modelled Tracer Batch model Surface sorption Matrix diffusion TRUE BS Continuation batch model sorption experiments on rim zone K m Ka m Ka m kg 2000 Byeg rd and Tullborg I 1 8E 3 Not modelled Cs l
79. uantitative extraction of Cs from a one litre solution to a syringe filter was shown by Byegard 2002 Consequently if one litre samples are available the detection limit should be possible to decrease to 50 mBq per litre 63 12000 30000 10000 25000 1 180 a 180 320 m 1 1024 8000 r 20000 6000 I 37 1 counts Count rate cpm 4000 2000 0 10 20 30 40 50 Chn Elapsed time d Figure A 2 Liquid scintillation spectrum left for sample 5 treated with ammonium molybdenum phosphate Results are given for a number of different times days after the preparation of the liquid scintillation sample To the right the decrease of counting rate versus the elapsed time is presented The dots represents the measured value and the line shows the projected decrease of the counting rate based on the tabulated half life of Cs 9 69 d 64 30000 12000 25000 1 180 4 180 320 N a 1 1024 10000 I 20000 8000 15000 6000 w N a Count rate cpm counts gt 10000 4000 5000 2000 ee 0 10 20 30 40 50 Elased time d Chn Figure A 3 Liquid scintillation spectrum left for sample 5 without treatment with ammonium molybdenum phosphate Results are given for a number of different times days after the preparation of the liquid scintillation sample T
80. y concentration is divided by the total activity injected 41 1 0E 02 el O Cs E Ca2 Cd2 m Lu lll A Hf IV e Np V O2 1 0E 03 cz gu 1 0E 04 lt o o 1 0E 05 on Filtrated sample 20nm Y 31 1 0E 06 i 1 0E 02 1 0E 01 1 0E 00 1 0E 01 1 0E 02 Elapsed time d Figure 17 Relative concentration versus elapsed time curves for samples dots and on line measurements lines in logarithmic scale The radioactivity concentration is divided by the total activity injected 3 4 3 Sorption on tubing Sorption of the only remaining non decayed tracer Hf on tubing was measured on a 20 cm tubing sample A slight sorption of about 5 to 10 Bq m was observed after 2 months which corresponds to about 0 5 to 1 kBq for an estimated total tubing length of 100 m The total injected amount of Hf was 14 kBq and after 2 months gt 99 of Hf was sorbed Consequently only a minor part of the Hf which was the most strongly sorbing tracer used is estimated to be sorbed on the tubing lt 7 of the sorbed amount An indication of the sorption on the tubing can also be seen in Figure 17 where the concentration determined in samples and on line differs for Hf and Lu at the end of the experiment 3 4 4 Evaluation of surface sorption Ka with simple batch sorption model Surface sorption coefficients were evaluated as described in section 2 4 1 assuming that all sorption occurred on the geometrical surfaces of the s

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