Decommissioning of Nuclear Facilities

1. Decommissioning of Nuclear Facilities

2. Decommissioning Definition: The process of safely closing a facility from service where nuclear materials are used at the end of the facilities’ useful life. Reasons for decommissioning: • Too expensive to operate, maintain, or repair to maintain operational compliance • Lack of necessity for nuclear facility • Risk to Benefit ratio is too low (congressional wisdom)

3. NRC: 10 CFR 50.82Termination of License Purpose: The purpose of decommissioning is to remove the nuclear facility from service and to reduce the residual radioactivity so that the operating license may be terminated and the property may be released under restricted or unrestricted conditions. Facilities Effected: • Nuclear Power Plants (the most difficult) • Chemical Plants (that handle nuclear products) • Conversion plants • Reprocessing plants • Fabrication Plants ( these facilities decommissioning equate to decontamination)

4. Beginning Decommissioning Process • When it has been determined to cease operation of a nuclear power facility, a written certification, license termination plan (LTC), must be written within 30 days of the determination to the NRC consistent with guidelines of 10 CFR 50.4(b)(8) • Once all of the fuel has been removed from the core, another written certification (LTC) must be submitted under guidelines 10 CFR 50.4(b)(9) • Written certification can be made for cease of operation with retention of fuel in the core • Decommissioning is addressed in 10 CFR 50. Some parts are addressed in parts 20, 30, 40, 51 ,70, 72, and the “Decommissioning Resource Manuel”

5. Beginning Decommissioning Processcont. • Upon docket of permanent cessation of operation and removal of fuel or legal order to cease operation, the post-licensee has 2 years to submit a post-shutdown decommissioning activity report (PSDAR) to the NRC and the affected state. • No major decommissioning activity may start until 90 days after PSDAR submittal (i.e. removal of hazardous materials) • Nuclear power facilities with multiple reactors may apply for a partial site release. The NRC will have to approve the license termination plan (LTC)

6. PSDAR • A description of planned decommissioning activities and completions • Estimation of expected cost • A report that concludes that previous environmental reports will substantiate the current environmental report parameters associated with the decommissioning site. It will discuss the appropriate activities associated with the decommissioning of the site • Decommissioning will be completed in 60 yrs. Extensions may be granted by NRC if public health and safety are a consideration

7. Key points of Decommissioning Plan • Hazardous LLW’s removal procedure • Return to unrestricted use plan (unless site has more than one reactor, a partial site release is required ) • Safety procedures and protocols (i.e. disposal of radioactive waste procedures/methods and disposal locations) • Financial plan of decommissioning (includes removal of spent fuel and removal of nonessential equipment necessary to license termination. • Record keeping and time management • ALARA

8. Decommission Completion • Radioactive components have been removed from the site • Site Decontamination performed (if necessary) • Total Effective Dose Equivalent (TEDE) to an average member of the critical group is less than .25 mSv/yr • Critical Group - the group of individuals expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances (one or several groups considered) • TEDE for restricted use must be .25 mSvwith institutional controls and 1 mSv with no institutional control. Institutional control – fences, restriction of use of site(i.e. parking, farming), access restriction

9. Total Effective Dose Equivalent International Commission on Radiological Protection (ICRP) • Leading agency that provides recommendations for radiological safety • Introduce detailed technical regulations • Develop codes of practice best suited for countries to protect their citizens • ICRP Publication 60 recommends EDE limits for exposure ICRP Basic Radiation Safety Criteria (Groups) • Occupational exposure • Pregnant women • Radiation workers • General public exposure • Medical Exposure (diagnostic and therapeutic)

10. Total Effective Dose Equivalent ICRP Basic Radiation Safety Criteria (Groups) • Occupational exposure • Pregnant women • Radiation workers • General public exposure • Medical Exposure (diagnostic and therapeutic) Dose Limit System • Non-stochastic Effect – assumes a radiological dose has a threshold before an effect takes place • Stochastic Effect – assumes that any radiological dose has the capacity : the to have an effect; the only safe radiological dose is zero .

11. Total Effective Dose Equivalent ALI (Annual Limit of Intake) The derived upper bound of allowed radiological dosage that may not be exceeded per year. (workers = 2000 hours) • Compliance is determined when the summation of the effective dose equivalent plus the committed effective dose equivalent value is less than 1. + x

12. Decommission Completion Steps to a successful Decommissioning: • Create an advisory committee with local people participation • Calculate the residual radiation level as closely as possible • Model and compute the exposure probabilities of workers and the public. • ALARA • Protect the ground water per EPA guidelines

13. Decommissioning Methods • Decommissioning doesn’t include used nuclear fuel • Disposal of LLW’s and TRU leaked into coolant from fuel rods • Cost and exposure risk are major contributors to method decision Three methods • DECON – dismantle; all materials, equipment, machinery, radiological sources, etc. are removed. Upon completion, the license is terminated and the site is released as unrestricted • SAFSTOR – mothballing; radioactive material are removed. Equipment and machinery is secured and monitored. The site is licensed as restricted use until the plant is dismantle. • ENTOMB – entombment; the site is encased in concrete and monitored until the radiological levels reduce to unrestricted levels

14. Decommissioning Methods Major Considerations for deciding decommissioning method • Whether or not other nuclear generating facilities are on site • Current and projected waste facility site availability • Current and projected cost of decommissioning and funding availability • Regulatory outlook

15. Decommissioning Methods • Two types of waste for disposal during process • Leaked transuranic (TRU) in the fuel • Contaminated equipment due to neutron absorption (i.e. heat exchangers, instrumentation cables, steam generators, reactor coolant pumps, pressurizer, and the reactor pressure vessel ) • Both inside and outside of the reactor • Most Important Isotope to dispose – Co-60, Ni-59, Nb-94, and Eu-152 due to long half life and radiological concentrations

16. Decommissioning Methods

17. Decommissioning Methods

18. Decommissioning Methods

19. Decontamination Methods The process of transferring radioactive material from one surfaces to another for disposal Benefits: • Lowers the volume of LLW and decreases cost of disposal • Lowers radiation exposure to workers 4 methods of decontamination • Chemical • Physical • Electropolishing • Ultrasonic Janitorial methods are done prior to these methods

20. Decontamination Methods Chemical • Chemical solution used to remove radioactive materials • Solution type depends on the radioactive material and the surface Physical • Pressure washing, jack hammering, pneumatic disk, etc. are used to remove radioactive materials • Debris is package and shipped to a LLW repository Electropolishing • Radiactive metal surfaces are put in an phosphoric acid. The surface creates a negatively charged terminal. Electric current is applied to metal surface. A atomic layer is removed with the electrical current which carries the radionuclide.

21. Decontamination Method Ultrasonic Method • Used on valves and pumps • Items are placed in a bath of liquid. Ultrasonic waves are applied to the bath. Waves create a pressure of 10,000 psi and dislodge the material from the item • Abrasives and chemicals may be added to the liquid to increase effectiveness of process.

22. Assurance of Funds for Decontamination Prepayment (preferred) External Sinking Fund • Trust • Escrow Account • Govt. funds Certificate of Deposit • Deposit of Govt. Security Surety Method, insurance, or other guarantee method • Surety bond (open ended and automatically renewable) • Must close surety in writingZ • Letter of credit ( • Line of Credit Cost depends on plant size, plant design, and local labor markets

23. Assurance of Funds for Decontamination

24. Assurance of Funds for Decontamination

25. Assurance of Funds for Decontamination

26. Assurance of Funds for Decontamination

27. Obstacles to Decommissioning Affecting Cost • LLW’s Facilities in the long term for storage • Transition personnel from operation professional to shutdown/dismantlement professionals • Regulatory transition • Government uncertainty • SNF/HLW remaining on site issues (i.e. transportability, canister licensing) • Aging Management • Operating margins no longer supporting operation due to: • Environmental hurdles • Aging facilities too costly to repair • Independent Spent Fuel Storage Installation (ISFSI) • Safety (exposure)

28. Obstacles to Decommissioning Affecting Cost (cont.) • Competitive price of natural gas (“fracking” lower cost of natural gas extrusion from 12.50 per thousand cubic ft. to 4.85 per thousand cubic ft.)

29. Transport of LLW’s(Containers) • LSA material (low specific activity) – non-fisslie material that have an activity set below those prescribed by 10 CFR 71.75 • May be packaged in a “essentially” Type A packaging if determined “nonexclusive use” • Essentially – not having to meet all of the testing for Type A packaging • Guarantee of loading procedures must be presented and adhered to • Dose rates of packaging must meet guidelines

30. cont. • Stability Requirements • Must be able to maintain structural integrity under disposal conditions • Must be noncorrosive at 1% waste volume or .5% of waste volume in stable form • No void spaces in packaging • Clearly identified in designated • classes

31. Transport of LLW’s(Containers) Nonexclusive LSA Type A container transport criteria • 2mSv/h at any point of packaging • If higher, an exclusive vehicle must transport the materialand satisfy additional criteria • 10 mSv if shipment is in a closed vehicle • 10 mSv if materials are secures to avoid material movement during transport • 10 mSv if materials are not unloaded and loaded during the trip • 2 mSv/h at any point on external surface of vehicle • 0.1 mSv/h at any point 2 meters from surface of the vehicle • 0.02 mSv/h in any normally occupied space (i.e. driver cab)

32. Calculating Package Classification with Several Radionuclides The Fraction Rule 1 Apply this equation when there are more than one isotope in a package • If the isotopes are in the same column of Table 1 or Table 2, add the summation to find if their sums equal more than or less than one. If more than one, the next higher class is designated for the class. • The isotope of the most restrictive class designates the class of the package if two isotopes of different Tables and/or columns are in the LLW package.

33. Transport of LLW’s(Containers) • Covered in 10CFR 71 and 49 CFR 173 • Packages must pass test to satisfy shipping requirements • Three type of containers allowed for shipping • Type A package – capable of withstanding normal conditions of transport without leaking of radioactive contents. • Class A radionuclides or a mix thereof may be packaged into Type A packaging • Examples (fiberboard box, wooden box, steel drum

34. Transport of LLW’s(Containers) • Type B package – capable of withstanding normal and accidental transport conditions without leaking radioactive contents. • Class B radionuclides must be transported in in Type B packaging • Examples (Steel drum outer layer, shielded inner layer, thermal insulation between layers)

35. Examples of Low Level Waste Examples of radioisotopes contaminated items like: • Clothing • Tools • Swipes • Trash • Liquids Low Level Waste sources include: • Nuclear plants • *Research Laboratories • *Hospitals • Radiopharmaceutical Laboratories • *Industrial Facilities

36. Classification of LLW’s(Near surface burial disposal site permitted for LLW packages) Class A – This class has the least amount of radioactivity • Radionuclides not listed in Table 1 or Table 2 • Radionuclides of Table 1 at 10% or less of concentration listed in Table 1 • Radionuclides of Table 2 at concentrations equal to or less than the value in Col.1 of Table 2 Class B • Radionuclides of Table 2 that have concentration values greater than Col. 1 yet less than Col.2 Class C • Radionuclides of Table 1 with concentrations greater than 10% of the value listed in Table 1 • Radionuclides of Table B with concentration values greater than Col. 2 and less than values listed in Col.3 Class GTCC (greater than class C) • Radionuclides of Table 1 with concentrations greater than the value listed in Table 1 • Radionuclides of Table 2 with concentrations greater than the values listed in Col.3

37. Classification of LLW’s(Near surface burial disposal site permitted for LLW packages) Examples of GTCC’s • Activated metals from reactors (decommissioning) • Reactor control rods • Cladding • Sealed sources • Medical (sterilizing products) • Industrial ( xrays to detect flaws in welds) • Radionuclides found in GTCC • Cs137Cl • Pu238 • Pu240 • Am241, Am243 • Cm244

38. LLW Disposal Requirements Minimum Requirements • Packaging in cardboard or fiberboard is prohibited • Liquid waste must be solidified (made not to leak) • In absorbent material • Liquid must not exceed 1% of waste • Waste must not be explosive • Waste must not be pyrophoric • Waste activity must be less than 100 Ci/container and contained at a pressure of less than 1.5 atm @ 20 degree Cel. Questions?