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2006 Nuclear Utility REMP Conference Isotopes Of Concern

2006 Nuclear Utility REMP Conference Isotopes Of Concern. General Engineering Laboratories, LLC. Environmental Levels And Methods For Monitoring H-3. C-14. Sr-90, Fe-55, Tc-99. Ni-63. Today We Will Review.

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2006 Nuclear Utility REMP Conference Isotopes Of Concern

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  1. 2006 Nuclear Utility REMP Conference Isotopes Of Concern General Engineering Laboratories, LLC Environmental Levels And Methods For Monitoring H-3. C-14. Sr-90, Fe-55, Tc-99. Ni-63

  2. Today We Will Review • H-3 Levels in US ground water, surface water and drinking water “Pick Your Background Level” • Compare NRC and EPA limits • Look at H-3, C-14, Sr-90, Tc-99, Ni-63 analytical methods and typical detection limits

  3. Tritium • Naturally occurring in rainwater at 40-150 pCi/L • The Tritium Unit (TU) is defined as: • 1 TU = 3.2 pCi • Concentration varies as a function of upper atmospheric conditions, solar conditions, and age of the ground water

  4. Environmental H-3 Levels In The United States (USGS Ground Water) • USGS Lists 5 types of H-3 Ground Water Levels Based on age of recharge from surface water • Less Than 0.8 TU (2.6 pCi/l) “Submodern” Prior to 1952. Analytically we call this dead water • 0.8TU(2.6 pCi/l) To 4 TU(13pCi/l) “Mixture between submodern and recent recharge • 5TU(16pCi/l) to 15 TU(50pCi/l) Modern Less than 5 years to 10 Years • Greater Than 30 TU(100pCi/l) Considerable Component of Recharge from 1960 to 1970’s • Greater Than 50(162pCi/l) TU Dominantly 1960 recharge

  5. Environmental H-3 Levels In The United States (EPA Surface Water Testing 1994 to 2000) • EPA testing of H-3 in drinking water taken from locations away from nuclear instillations list US H-3 levels ranging from 100 to 300 pCi/l • EPA testing of H-3 in surface water taken downstream from operating nuclear facilities ranges from 100 to 2,900 pCi/l (most locations tested had results less than 300 pCi/l) • A few of the sites that stand out are: 2,300 pCi/l (Savannah River ) and 2,900 pCi/l (Lake Robinson), 2,200 (North Anna River)

  6. So What is The H-3 Background In The US • USGS Data Shows Environmental H-3 ranging from 3 pCi/l to a high of 160pCi/l [GW] • EPA H-3 Drinking Water Results dating January 1994 – March 1994 range from 100 to 300 pCi/l [SW]

  7. I Think Its Safe To Say We Have More Than One H-3 Background Level • H-3 in ground water “aquifer” is less than 160pCi/l • H-3 in drinking water ranges from 100 to 300pCi/l

  8. Can You Write Off H-3 At Low Levels As Environmental Only? • Is your H-3 level above 160 pCi/l • Do you have a good understanding of the hydro-geology of your site • Can you have a radiological leak to the ground • Is it time to look harder • What To Do: Additional site wells, hydro-geology study of your site, and start looking for other isotopes (C-14, Sr-90, Tc-99, Ni-63)

  9. EPA MCL H-3 20,000 pCi/l C-14 2,000 pCi/l Sr-90 8 pCi/l Tc-99 900 pCi/l Ni-63 50 pCi/l NRC Values H-3 1E6 pCi/l C-14 3E4 pCi/l Sr-90 5E3 pCi/l Tc-99 6E4 pCi/l Ni-63 1E5 pCi/l NRC 10CFR20 Table 2 Effluent Values EPA MCL Values

  10. Analytical Methods for H-3 • H-3 decays by -, Emax 0.018 MeV • Liquid Scintillation • Typical MDA without sample enrichment runs about 500 pCi/l and with extended 4 hr counts you can push this down to 200 pCi/l (but the uncertainty at this level is about 100% relative to the actual measurement) • Typical MDA with sample enrichment runs about 3 pCi/l

  11. H-3 Beta Spectrum

  12. Analytical Methods For Very Low Tritium Detection • For H-3 Analysis at levels less than 200 pCi/l the gold standard is H-3 sample enrichment • Process takes 4 to 6 weeks • Samples go through an electrolytic enrichment step • Typical MDA is 0.1 TU or 0.3 pCi/l • Tritium Laboratory University of Miami (305) 361-4100

  13. Analytical Methods for C-14 • C-14 Decays by -, Emax 0.160 MeV • Liquid Scintillation • Acid Digested to remove all carbon as CO2 • The CO2 is collected on a chemical trap and determined using liquid scintillation counting • Typical MDAs for this test are 50 pCi/l

  14. C-14 Beta Spectrum

  15. Analytical Methods for Sr-90 • Sr-90 in secular equilibrium with Y-90 • Both decay by -, Emax 0.546Sr and 2.3Y MeV • Gas Flow Proportional Counting • Sr-90 is removed via EPA method 905.0 “Drinking Water Method” • Typical MDA is 2 pCi/l for Sr-90

  16. Analytical Methods for Tc-99 • Tc-99 Decays by -, Emax 0.294 MeV • Liquid Scintillation • The sample is oxidized to pertechnetate and removed via resin extraction • Typical MDA is 50 pCi/l

  17. Tc-99 Beta Spectrum

  18. Analytical Methods for Ni-63 • Ni-63 Decays by -, Emax 0.067 MeV • Liquid Scintillation • Analytical Chemistry to take all the nickel to nickel – DMG – precipitate. The precipitate is taken to a liquid phase via nitric acid • Typical MDA is 50 pCi/l

  19. Ni-63 Beta Spectrum

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