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Robert Schupfner Environmental Radioactivity Laboratory (URA)

Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities. LiquiScint 2004 17-18 May - Masaeykova kolej, Thákurova 1, Praha 6. Robert Schupfner Environmental Radioactivity Laboratory (URA) Institute of Analytical Chemistry, Chemo- and Biosensors,

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Robert Schupfner Environmental Radioactivity Laboratory (URA)

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  1. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities LiquiScint 2004 17-18 May - Masaeykova kolej, Thákurova 1, Praha 6 Robert SchupfnerEnvironmental Radioactivity Laboratory (URA) Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg robert.schupfner@chemie.uni-regensburg.de

  2. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Summary  Radiological Aspects of Decommissioning  General Conditions of Radioanalytical Methods  Application of Liquid Scintillation Counting (LSC) • 41Ca und 45Ca • 55Fe und 59/63Ni • 90Sr (90Y)  Results and Conclusion robert.schupfner@chemie.uni-regensburg.de

  3. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Demands of Radiological Safety for the Decommissioning of Nuclear Facilities  decommissioning personell and members of the public  before, during and after decommissioning  long-term ensuring of radioactive waste storage  complete radiological assessment including activity determination of single radionuclides as basic requirement robert.schupfner@chemie.uni-regensburg.de

  4. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Sample Materials  human excreta: urine, faeces  metals: steels, alloys  corrosion products  building materials: concrete, mortar, bricks  glass fibres  organic and inorganic chemical compounds  organic and inorganic chemical compounds  environmental materials: soils, sediment, plant, food, ... robert.schupfner@chemie.uni-regensburg.de

  5. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Which Analytical Problems Arise during Decommissioning of Nuclear Facilities ?  sample materials  physical decay properties of the radionuclides of interest  various mixtures of radionuclides  chemical behaviour  time scale  range of activities robert.schupfner@chemie.uni-regensburg.de

  6. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Radionuclides of Interest (not complete) robert.schupfner@chemie.uni-regensburg.de

  7. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Portions of Available Measurement Methods robert.schupfner@chemie.uni-regensburg.de

  8. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Application of Liquid Scintillation Counting (LSC Quantulus 1220) Active and passive shielding Minimising the background counting rates: • about 1 cpm for 3H, 41Ca, 55Fe, 241Pu • about 3 cpm for 14C, 63Ni • about 5 cpm for 99Tc, 129I • about 7 cpm for 89Sr, 90Y, 45Ca • about 2 to 3 cpm for a-emitters robert.schupfner@chemie.uni-regensburg.de

  9. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Application of Liquid Scintillation Counting (LSC) Advantages  low radiation energies  high counting efficiency  low background counting rates LSC Quantulus 1220  energy resolution enables an increased selectivity  low values of lower limits of detection  a variety of suitable scintillation cocktails is commercially available Disadvantages  as a rule application only after radio- chemical purification procedure  increased expense to assure high quality  high costs of low background counting devices (LSC Quantulus 1220)  energy resolution is rather limited  increased expense of sample preparation in sample solutions with high salt content  stability of sample-cocktail mixture in sample solutions with high salt content robert.schupfner@chemie.uni-regensburg.de

  10. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Quality of Radiochemical Analysis Applying LSC  selective  low values of detection limits  accurate and precise  efficient: fast, reliable, low costs robert.schupfner@chemie.uni-regensburg.de

  11. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 41Ca and 45Ca robert.schupfner@chemie.uni-regensburg.de

  12. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 41Ca und 45Ca Decay properties  dissolution of sample material (concrete)  radiochemical purification of 41Ca, 45Ca  optimising the sample preparation with a suitable scintillation cocktail  activity determination applying LSC Quantulus 1220 robert.schupfner@chemie.uni-regensburg.de

  13. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 41Ca und 45Ca Determination of Counting efficiencies of 41Ca versus Content of stable Ca2+ in the Sample Solution robert.schupfner@chemie.uni-regensburg.de

  14. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 41Ca und 45Ca Lower Limit of Detection (lld) of 41Ca versus Content of stable Ca2+ in the Sample Solution robert.schupfner@chemie.uni-regensburg.de

  15. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 41Ca und 45Ca A B C robert.schupfner@chemie.uni-regensburg.de

  16. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 41Ca und 45Ca  Minimum lld at about 1200 to 1300 mg Ca2+: 0,05 Bq 41Ca ·(g Ca2+)-1  value of lld is proportional to the activity A(45Ca) of 45Ca in the sample: lld (m) = lld (m, A(45Ca)=0) + k· A(45Ca) with: k 0,008 Bq 41Ca ·(g Ca 2+·Bq 45Ca )-1  assuming a content of Ca of about 20 % in concrete: the LSC method tolerates 5,5 to 7,5 g of concrete  minimum value of about 0,0141Ca ·(g concrete)-1 robert.schupfner@chemie.uni-regensburg.de

  17. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 55Fe and 59/63Ni neutron activation sth / barn 54Fe (n,g) 55Fe 2,25 58Ni (n,g) 59Ni 4,6 62Ni (n,g) 63Ni 14,2 robert.schupfner@chemie.uni-regensburg.de

  18. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 55Fe and 59/63Ni Decay Properties robert.schupfner@chemie.uni-regensburg.de

  19. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 55Fe and 59/63Ni • Decontamination factors are sufficiently high. • 105 to 109 for 55Fe • 104 to 1011 for 63Ni • Chemical yield • to about 120 mg Fe (92 ± 3) % • to about 40 mg Ni (95 ± 5) % robert.schupfner@chemie.uni-regensburg.de

  20. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) 89 90 90 Sr Sr Y 89 90 90 Starting nuclide As Se Se Fission yield 4,764% 5,835% 5,835% 90 89 90 Decay Product Y(stable) Y(radioactive) Zr (stable) Half Life Time 50,5 d 29,12 a 2,761 d -2 -1 -5 -1 -1 -1 Decay Constaqnt 1,37·10 d 6,52·10 d 2,51·10 d - - - b , (g) b b , (g) Decay Energy 583,3 keV 195,7 keV 934,8 keV -1 -1 -1 Probability Y 1 ( Bq ·s) 1 ( Bq ·s) 1 ( Bq ·s)  until now: high expense  development: significant less expense robert.schupfner@chemie.uni-regensburg.de

  21. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) 90Y is in radioactive equilibrium with 90Sr  Determination of chemical yield applying 88Y 88 88 - Y Sr + e y nuclide Half life time E/keV i -1 Decay / (Bq s) g -radiation Y-88 106,63 d 898,2 0,94 1836,0 0,9933 ec -radiation ca. 11 ca. 1  90Sr Determination after Liquid -Liqid Eytraction of 90Y using Di-(2-Ethylhexyl)-phosphate (C16H35O4P) HDEHP robert.schupfner@chemie.uni-regensburg.de

  22. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) Dissolution of Sample Material Containing 90Sr (90Y) Chemical Yield Tracer 88Y (11 Bq) Sample Solution Sr2+, Y3+ Liquid -Liquid Extraction of 90Y, 88Y in HDEHP Na+, K+, Cs+, Mg2+,Ca2+, Sr2+,Co2+, U, Pu, Am, and other interfering nuclides Re-extraction of 90Y, 88Y in 9 m HCl Washing Fe3+ LSC Precipitation of Y(OH)3 robert.schupfner@chemie.uni-regensburg.de

  23. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) robert.schupfner@chemie.uni-regensburg.de

  24. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) Fig. 1: LSC-Spectrum of 11 Bq 88Y and blank Fig. 2: LSC-Spectrum of 11 Bq 88Y and 21 Bq 90Y and blank robert.schupfner@chemie.uni-regensburg.de

  25. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) Parameters of determination of 90Sr (90Y) in concrete Parameter Material 9,9 g concrete Dissolution HCl (32 %) Analysis Extraction of Y with HDEHP Detection LSC Quantulus Berthold LB770 90 h ( Y) / Ips/Bq 0,79 ± 0,02 0,43 ± 0,01 phys. h /% 84 ± 7 chem. range of time /h < 0,1 1 radiometric titrimetric 88 Y(ca. 11 Bq) stable Y n /Ipm about 72 about 0,5 0 life time t /min 1000 1000 L lld/Bq/g 0,003 0,0005 ld/Bq/g 0,005 0,0008 robert.schupfner@chemie.uni-regensburg.de

  26. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y) •  Successful Participation in Official Comparison Analyses of the Federal Office for Radiation Protection (BfS) • Liquid Effluents; Water • Human Excretion (urine)  Br: 0,07; sA: 0,05; sB: 0,05 •  Soil Samples from 5 g to 100 g Br: -0,14; sA: 0,04; sB: 0,05 robert.schupfner@chemie.uni-regensburg.de

  27. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Example: 90Sr (90Y)  high and constant values of chemical yield (70 bis 90 %)  tolerates high amounts of sample material and salt freight , up to 100 g of soil minimum of lower limit of detection at 60 g of soil: about 1 mBq 90Sr /g (dry weight) applying low-level b-counter LB770; about 9 mBq 90Sr/g (dry weight) applying low-level LSC Quantulus 1220  application of the method of isotopic dilution (88Y) makes this analysis very fast (about 2 to 3 hours per sample and per one technichian)  increased selectivity with respect to interfering 152Eu in the sample using b-spectrometric abilities of the LSC- detection method robert.schupfner@chemie.uni-regensburg.de

  28. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Conclusion LSC is a important tool relieving analytical problems arising with decommissioning of nuclear facilities LSC is well suited detecting low-energy radiation emitting radionuclides as 41Ca, 55Fe, 59/63Ni, 241Pu  In combination with liquid-liquid extraction techniques LSC is well suited detecting 90Sr(90Y) even in complex sample materials  reliable radiochemical purification procedures are necessary to realise a sufficient selectivity, accuracy, precision, lower limit of detection  Increased efforts are required to fulfil high quality criteria  In future much work must be done in further research combining both radiochemical procedures and LSC methods robert.schupfner@chemie.uni-regensburg.de

  29. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Acknowledgement to  The members of the organising committee for inviting me to the beautyful city of Prague and for their help and for their patience  Mr. Gesewsky (†) from BfS-IHS for supplying us with the 41Ca solution  Dr. Günther from PTB, Braunschweig for certification of the 41Ca solution  All companies supplying us with the scintillation cocktails free of charge  The Bavarian State Ministry for State Development and Environmental Affairs for financial support  The Federal Office for Radiation Protection for financial support  All co-workers of my laboratory robert.schupfner@chemie.uni-regensburg.de

  30. Application of LSC Methods on Radiochemical Problems Arising with Decommissioning of Nuclear Facilities Thank you for your attention and your patience If there are further questions, please ask me, I`ll try to answer them. robert.schupfner@chemie.uni-regensburg.de

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