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NS&E 618

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  1. NS&E 618 September 26, 2003 Objectives Review of Waste Classification Identification, and Treatment of Gaseous Radioactive Wastes GAB - NSNE 618

  2. Fission GAB - NSNE 618

  3. On the homework • Still worrying about radiation-Ci calculation • Suppose you have a line (cylinder) source and place a survey meter on the outer diameter GAB - NSNE 618

  4. Websites • http://www.westrain.org/WReactor/ThermodynamicsCh3.PDF steam jet • http://www.nucleartourist.com/ views of a nuclear reactor • http://www.eas.asu.edu/~holbert/eee460/nucleartopics.html#EEE460-Waste excellent waste links • http://www.philrutherford.com/radiation_software.html radiation computation software I recommend that you download and install “radiation decay” GAB - NSNE 618

  5. Waste Classification Not radioactive Air Water Soils Solids - No BRC 10 CFR 20 App. B NRC and EPA allow Perf. Based Definition GAB - NSNE 618

  6. Waste Classification Based on Radioactivity Spent Fuel, HLW (First Cycle Raffinate) 10 CFR 60; and 10 CFR 63 LLW A B C GTCC TRU -- A DOE Category only -- If there were significant commercial quantities there might be commercial TRU, but there isn’t 10 CFR 61 10 CFR 61 GAB - NSNE 618

  7. NRC Waste Categories • Class A • Low levels of radiation and heat, no shielding required to protect workers or public, rule of thumb states that it should decay to acceptable levels within 100y. • Class B • Has higher concentrations of radioactivity than Class A and requires greater isolation and packaging (and shielding for operations) than Class A waste. • Class C • Requires isolation from the biosphere for 500 years. Must be buried at least 5 m below the surface and must have an engineered barrier (container and grouting). • Greater Than Class C • This is the LLW that does not qualify for near-surface burial. This includes commercial transuranics (TRUs) that have half-lives>5y and activity>100nCi/g. GAB - NSNE 618

  8. 10 CFR 61 Table 1 GAB - NSNE 618

  9. Table 1 Rules • If the concentration does not exceed 0.1 times the value in Table 1, the waste is Class A. • If the concentration exceeds 0.1 times the value in Table 1 but does not exceed the value in Table 1, the waste is Class C. • If the concentration exceeds the value in Table 1, the waste is not generally acceptable for near-surface disposal. • For wastes containing mixtures of radionuclides listed in Table 1, the total concentration shall be determined by the sum of fractions GAB - NSNE 618

  10. 10 CFR 61 Table 2 There are no limits established for these radionuclides in Class B or C wastes. Practical considerations such as the effects of external radiation and internal heat generation on transportation, handling, and disposal will limit the concentrations for these wastes. These wastes shall be Class B unless the concentrations of other nuclides in Table 2 determine the waste to the Class C independent of these nuclides. GAB - NSNE 618

  11. Table 2 Rules • If the concentration does not exceed the value in Column 1, the waste is Class A. • If the concentration exceeds the value in Column 1, but does not exceed the value in Column 2, the waste is Class B. • If the concentration exceeds the value in Column 2, but does not exceed the value in Column 3, the waste is Class C. • If the concentration exceeds the value in Column 3, the waste is not generally acceptable for near-surface disposal. • For wastes containing mixtures of the nuclides listed in Table 2, the total concentration shall be determined by the sum of fractions rule GAB - NSNE 618

  12. Rules for Table 1&2 Wastes • If radioactive waste contains a mixture of radionuclides, some of which are listed in Table 1, and some of which are listed in Table 2, classification shall be determined as follows: • If the concentration of a nuclide listed in Table 1 does not exceed 0.1 times the value listed in Table 1, the class shall be that determined by the concentration of nuclides listed in Table 2. • If the concentration of a nuclide listed in Table 1 exceeds 0.1 times the value listed in Table 1 but does not exceed the value in Table 1, the waste shall be Class C, provided the concentration of nuclides listed in Table 2 does not exceed the value shown in Column 3 of Table 2. • Classification of wastes with radionuclides other than those listed in Tables 1 and 2. If radioactive waste does not contain any nuclides listed in either Table 1 or 2, it is Class A. GAB - NSNE 618

  13. Waste Classification Application - What are These? Off Spec Fuel Elements Sludge from Neutralized HLW Tanks (SR, HANF, WVDP) Supernate from Neutralized HLW Tanks Pump withdrawn from a Neutralized HLW Tank 4000 Ci Medical Cobalt source (1 in diam x 4 in long) INEEL Sodium Bearing Waste GAB - NSNE 618

  14. Waste Classification Application, cont. Failed Am-241 smoke detector source (2 Ci in a dime-sized capsule) 500 Ci H-3 source Reactor metal in a 55 gal drum with 50 mCi Nb-94 Drum (55 gal) containing Cs-137 reading 100 mR/hr at surface GAB - NSNE 618

  15. Waste Classification Application, cont. 1 acre pond, 4 ft deep with 10 mCi Cs-137 Waste from RFP Graphite from production reactors Cs-137 capsule from Hanford 35 kCi Pressurized tank containing 1000 Ci Kr-85 GAB - NSNE 618

  16. Origins of Gaseous Species Activation C-14 (as CO or CO2 N-16 Ar-41 Fission Kr-x Xe-x Other - H-3 - Radon GAB - NSNE 618

  17. Topics Source of gaseous releases, 0.12 % failure of fuel cladding Removal and decay of noble gases Radiolytic hydrogen and oxygen for BWR and nitrogen recycle in PWR GAB - NSNE 618

  18. Major Gaseous Wastes of Concern H2 and O2, radiolytically generated, non-radioactive Kr-85 - Reactor release, fuel reprocessing N-16 - short term reactor area H-3 -long term cumulative conversion to and mixing with groundwater C-14 conversion to hydrocarbons or carbonates and disposed of as solid LLW GAB - NSNE 618

  19. Radioactive Waste Gases Fission Products – H-3, Kr, Xe, I2 Activation Products – C-14, N-16, A-41 PWR and BWR have different situations Objective is to keep reactor releases to less than 1 Ci/y or be safe BWR continuously cycles coolant out of the pressure vessel PWR retains coolant for up to 6 months GAB - NSNE 618

  20. PWR GAB - NSNE 618

  21. BWR GAB - NSNE 618

  22. SJAE Note benefits of a SJAE: Motive force is steam No moving parts Upon cooling, the steam is just water GAB - NSNE 618

  23. Recombination of H2 and O2 BWR generates about 150 scfm of H2 and 75 scfm of O2 . (Decomposition of H2O gives 2 moles of H2 for each mole of O2 There is also about 75 scfm air in leakage, and 40 scfm of water vapor Note that the Kr and Xe are trivial amounts compared to this and the tritium is in the water Since the steam is condensed to water after passing through the turbine, if this gas is not removed, it will lock the turbine or lead to an explosion or both. Once removed it is explosive, and must be kept below 4% H2 Therefore, there is a requirement for an effective catalytic recombiner 2H2 +O2 => H2O operating at less than 500 C GAB - NSNE 618

  24. Calculations on Kr-85 Generation Estimate Kr-85 production from thermal power only Discuss issues to be considered (on separate file -- “Krypton Released from a Reactor”) Note that this approach is applicable to all other fission products GAB - NSNE 618

  25. Treatment of Noble Fission Product Gases PWR and BWR are different PWR retains gases in primary coolant and most decay occurs there BWR continually removes gases shortly after they are produced, they must be decayed in order to allow safe release. See xls. spread sheet computations GAB - NSNE 618

  26. Topics of Special Note Basis for small particulate filter needs Hydrogen recombination Special note on Steam Jet Ejector Tritium Combines with oxygen to form Tritiated Water Can be separated via distillation, electrolysis, catalytic exchange Extremely expensive when you consider the levels to be separated GAB - NSNE 618

  27. High Curie Releases • The 270 – 300 Ci of Kr release greatly exceeds the normal standard of <1 Ci/y, that is why we have a “license to release” • Recall, 99.9% of the Kr-85 is still in the fuel. The THORP reprocessing plant in England fought long and hard to operate because at 300 tons per year, it would release about 3*1000*300 Ci/y of Kr-85 • Tritium annual releases are a about 400 Ci • Review 10 CFR 20 Appendix B • Foot note 1 for H-3 1E-7 microCi/ml in “semi-infinite cloud” • Similar with Kr-85 7E-7 microCi/ml and Xe GAB - NSNE 618

  28. Summary of Treatment of Radioactive Gases Capture and decay Xe and Kr Kr will become a problem for major fuel reprocessing Tritium remains a background annoyance Release and distribute the rest Major waste gas problem is radiolytic non-radioactive hydrogen and oxygen Radon - learn to cope with it. GAB - NSNE 618