Generation of Radioactive Waste

1. Generation of Radioactive Waste Radioactive Waste Management and Disposal NUCP 2311

2. Sources of LLW • Defense and other national programs • Commercial nuclear power • Medical research activities • Academic research activities • Industrial activities

3. Licensees (non-DOE) • NRC regulates about 6,700 licensees • 37 agreement states have responsibility • Agreement states regulate about 15,000 radioactive materials licenses

4. Sources of Disposed LLW (1994-95)* • Nuclear reactors - 44.0% 55% • Industrial users - 39.9% 24% • Government sites - 13.4% 19% • Academic users - 2.1% 1% • Medical facilities - 0.6% 1% • * total volume 858,677 ft3 690,000 ft3

5. Nuclear Reactors

6. Commercial Nuclear PowerReactors in the United States

7. Nuclear Fuel Cycle

8. Nuclear Power Reactors • Ion exchange resins • Filters • Concentrated liquids • Dry active waste (DAW) • Decommissioning wastes • BWRs usually generate more LLW than PWRs

9. Ion Exchange Resins • Organic beads or granules designed to remove radionuclides from liquids • May be either anion or cation resins • When exhausted must be regenerated or replaced • Regeneration produces chemical waste which must be disposed Modified from J. Poston, Sr. Lectures

10. Ion Exchange Resins • Chemical waste usually concentrated by evaporation and solidified prior to shipment for disposal • Spent resins transferred by slurry to shipping containers • Must be “dewatered” prior to shipment • Some resins are solidified in cement or a polymer prior to shipment Modified from J. Poston, Sr. Lectures

11. Ion Exchange Resins • Radionuclide concentrations may be high enough to require shielding • Must be concerned about radiolytic gas generation • Chemical or biological degradation may occur in some resins • Need to be careful so that the resin does not become greater than class C waste

12. Filters • Cartridge filters – contain disposable elements made of woven or wound fabric, or pleated or matted paper supported on a SS mesh • Precoat filters – use filter aids, such as diatomaceous earth, powdered mixtures of cation- and anion-exchange resins, and high purity cellulose fibers Modified from J. Poston, Sr. Lectures

13. Filters • Cartridges are disposed as radioactive waste directly when replaced • Precoat filters are removed by “back-flushing” and disposed of as “dewatered” but unsolidified waste • PWR’s typically use cartridge filters whereas BWR’s typically use precoat filters Modified from J. Poston, Sr. Lectures

14. Concentrated Liquids • Evaporators are used to reduce volume • Concentrated liquids are known as “evaporator bottoms” • Have a high solids content and an average density in the range 1.0 to 1.2 g/cm3 • Usually are solidified prior to disposal Modified from J. Poston, Sr. Lectures

15. Dry Active Waste (DAW) • Applied to a wide variety of waste products • May be compactable or non-compactable • May be combustible or non-combustible • Volume varies based on activities at the site • Characterization of waste is important to disposal decisions Modified from J. Poston, Sr. Lectures

16. Dry Active Waste Treatment • Compaction • Baling • Shredding • Sectioning • Combustion • Decontamination Modified from J. Poston, Sr. Lectures

17. Example • Minimization of Low-Level Waste (LLW) at Nuclear Reactor Sites. • Consider a typical example in the United States.

18. Example for Discussion • Two-unit pressurized water reactor (1125 MWe). • Sorting/segregating dry active waste (DAW). • Free release of clean trash. • Laundry operations.

19. Motivation • Reduce waste generation. • Reduce disposal costs. • Take advantage of other disposal options. • Recycle materials where possible. • Make employees aware of important of waste minimization.

20. DAW Collection and Segregation • Collected in washable nylon bags. • Brought to waste collection areas. • Screened according to dose rate. • Placed in collection boxes. Modified from J. Poston, Sr. Lectures

21. Dose Rate Screening • If dose rate >2 mR/h, placed in a container for shipping to an off-site facility. • If dose rate <2 mR/h, sent to sorting and segregation facility. • Contents of these bags are sorted for free release. • Contaminated items combined in plastic bags and placed in container with >2 mR/h waste. Modified from J. Poston, Sr. Lectures

22. Monitoring the <2 mR/h DAW • Each bag is opened and the contents monitored at a sorting table. • Table contains 4 400-cm2 gas-flow hand-held proportional counters. • Each item monitored individually and clean and contaminated items are separated. • Trash is rebagged and routed based on the results. Modified from J. Poston, Sr. Lectures

23. Monitoring the <2 mR/h DAW • Clean trash is monitored again with a large, rotating NaI(TI) detector. • Bags passing monitoring are considered “clean” and disposed. • Bags failing this monitoring may be resorted and/or considered contaminated. Modified from J. Poston, Sr. Lectures

24. Results of Program • Monitored a total of 162,235 lbs of waste. • Monitored 117,378 lbs of clean trash. • Clean trash release rate ~ 89%. • Monitored 44,857 lbs of <2 mR/h DAW. • DAW free release rate ~ 65%. Modified from J. Poston, Sr. Lectures

25. Results of Program • Cost of program estimated to be about $0.70 per pound of waste monitored. • Clean trash savings estimated at $56,300. • <2 mR/h DAW savings estimated at $210,800. • Total savings over 18-month period $267,100. Modified from J. Poston, Sr. Lectures

26. On-Site Laundry Operations • Waste minimization often produces an increase in launderable goods. • Replaced disposal goods with launderable products. • Made decision to wash other items that, in the past, might have been disposed. Modified from J. Poston, Sr. Lectures

27. On-Site Laundry Operations • Concluded cost was about the same as using a commercial operation. • Avoids shipping and receiving problems associated with commercial operations. • Actual cost less because less anti-C clothing required in inventory.

28. Medical and Academic Institutions

29. Institutions • Liquid scintillation counting fluids • Organic and inorganic liquids • Biological wastes • Trash • Sealed sources and accelerator targets

30. Institutions (primary isotopes) • Typical Radionuclides • 3H, 14C, 32P, 35S, 51Cr, 57Co, 60Co, 90Sr, 99mTc, 125I and 192Ir • Used in research , diagnostics and treatment • Other, short-lived radionuclides are stored for decay before disposal • Some radionuclides can be sent down the sanitary sewer ( C-14, H-3) • 0.o5 uCi/ml • Water soluble • 5Ci/yr limit • Material that are waste products of patients are excluded from regulation

31. Liquid Scintillation Fluids • Often contain flammable organic fluids – a mixed waste (i.e., radioactive and hazardous chemical). • May be disposed by incineration. • Switch to aqueous-based scintillation fluids – dispose in the sanitary sewer.

32. Biological Wastes • Generated by research programs – generally have low specific activity. • Consists of animal carcasses, tissues, animal bedding and excreta, vegetation, & culture media. • May contain pathogenic or carcinogenic substances.

33. Biological Wastes • Care required in packaging because of biodegradation. • Material often shipped with absorbent paper and lime. • Some facilities use incineration of much of this waste. • Off-gas control and economics “drive” the solution • Exceptions for biological waste

34. Trash • Differs from that at nuclear power plants. • Most is compactable and combustible. • Incineration is often the disposal method of choice. • Some use of sorting, storage and compaction are also used.

35. Industrial Waste

36. Industrial • Industrial applications of radioactive material can be found in almost every industry; • Chemical • Petrochem • Steel mill • Mining • Food production • Paper mills • Hospitals • Coal burning power plants

37. Sources Sources that are used in industry can be anywhere from H-3 to Am-241 mostly Cs-137 and Co-60 Activities range from mCi to 1000s Ci Usually in sealed sources Sources that are too old to make readings are disposed of----- waste Can not reuse because of unknown integrity of capsule

41. Point Level or Density Gauge Source Head Detector Beam angle is approximately 130. rti

42. Continuous Level Gauge Source Head Detector Beam angle can vary from around 30o to better than 45o. Scatter Field rti

43. Government

44. Low-Level Waste Management (DOE) • Many activities within the DOE complex similar to those we have already discussed. • Largest volume of LLW is managed by the Office of Environmental Restoration (ER). • Other waste generated by DOE activities is transferred to the Office of Waste Management. Modified from J. Poston, Sr. Lectures

45. Low-Level Waste Management (DOE) • LLW is segregated into contact-handled and remote-handled waste just as with TRU waste. • Some wastes may contain transuranic radionuclides. • LLW containing hazardous waste or PCBs is handled separately. • DOE manages some NORM and NARM. Modified from J. Poston, Sr. Lectures

46. Sources of LLW at DOE Sites • Process, create, or handle radioactive materials. • Chemical conversions or separations. • Fabrication of nuclear components. • Support activities. • Pretreatment of HLW. Modified from J. Poston, Sr. Lectures

47. Sources of LLW at DOE Sites • Environmental restoration activities • Facility deactivation • Facility decommissioning • Facility demolition • Treatment and handling of TRU waste • Treatment and handling of mixed LLW Modified from J. Poston, Sr. Lectures

48. DOE LLW Disposal • Current approach is to use shallow-land burial facilities. • Disposes LLW at six sites and buried waste is present at eight additional sites. • Active sites include Hanford, Idaho Falls, Los Alamos, Nevada, Oak Ridge, and Savannah River. Modified from J. Poston, Sr. Lectures

49. Low-Level Waste from Nuclear Weapons Production Modified from J. Poston, Sr. Lectures

50. Low-Level Waste from Nuclear Weapons Production Modified from J. Poston, Sr. Lectures