What's New in Decommissioning of Nuclear Facilities

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Recent and Upcoming Meetings and Activities

The NRC consolidated its decommissioning guidance in a three volume NUREG-1757 series, which was originally issued in 2003.  NUREG-1757, Volume 2 was recently revised (Revision 2) and issued for public comment in December 2020.  Over 200 comments in 9 comment letters were received on the draft document.  The NRC has addressed most of the comments and plans to issue a final NUREG-1757, Volume 2, Rev. 2 in the summer of 2022.  NUREG-1757, Volume 1 is also in the process of being revised (Revision 3) and is expected to be issued in fall 2022.  Other decommissioning guidance document revisions that were recently issued include:  NUREG-1507, Rev. 1, “Minimum Detectable Concentrations with Typical Radiation Survey for Instruments for Various Contaminants and Field Conditions”, and NUREG-1700, Rev. 2, “Standard Review Plan for Evaluating Nuclear Power Reactor License Termination Plans”.  MARSSIM Rev. 2, draft for public comment, (NUREG-1575, Rev. 2) was also issued for public comment.  The public comment period was recently reopened on December 28, 2021, for 45 days with the public comment period ending on February 11 (see 86 FR 73757). The MARSSIM working group is currently addressing comments on the draft report.


Some comments received on NUREG-1757, Volume 2, Rev. 2 were more difficult to address (comments on subsurface surveys and discrete radioactive particles) and are expected to result in significant changes to the guidance document.  Therefore, the NRC plans to take additional time to address those comments and provide opportunities for interested stakeholders to weigh in on the need for revised guidance prior to incorporation of the guidance in the next revision to NUREG-1757, Volume 2. The interim guidance development section below provides additional information on the potential need for additional guidance in the areas of subsurface surveys and discrete radioactive particles, as well as historical and more recent information pertinent to the guidance that is being considered in making a decision on draft interim guidance.  The following table lists upcoming meetings and activities to keep interested stakeholders informed of NRC progress on guidance development as well as provide information on opportunities for public participation in the guidance development process.


Meeting/Activity Date/Timeframe Meeting Notice/Notes
RIC Virtual 2022

(Reactor Decommissioning Session)

March 8-10, 2022 Session W14, Reactor Decommissioning: Planning for Tomorrow. The W14 virtual session focuses on initiatives and enhancements within the reactor decommissioning program. Presenters will highlight the overall program status, key accomplishments in the decommissioning program, resource initiatives to enhance the program, and implementation of “Be RiskSMART” initiatives.  Session W14 was held on Wednesday, March 9 at 1:00 pm. Watch the video of Reactor Decommissioning: Planning for Tomorrow. A digital exhibit on Subsurface Soil Surveys and Characterization—Research Update is also available on the RIC web site.
Public comment period for proposed rule “Regulatory Improvements for Production and Utilization Facilities Transitioning to Decommissioning” March 3, 2022 – August 30, 2022 See NRC’s dedicated web page with a link to the proposed rule and related documents.
Public Meeting on Discrete Radioactive Particles (DRP) Fall 2022  
Issuance of Final SC&A Subsurface Technical Letter Report Summer 2022  
Final NUREG-1757, Volume 2, Rev. 2 Summer 2022 The public comment period ended in April 2021.  Over 200 comments in 9 comment letters were received on the draft document. The final report is coming soon.
Issuance of NUREG-1757, Volume 1, Rev. 3, Draft for Public Comment Fall 2022  

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Interim Guidance Development

Because the NRC’s Consolidated Decommissioning Guidance is only updated every few years, interim guidance can be used between guidance revisions to communicate methods to demonstrate compliance with radiological criteria for license termination related to important topics of interest to NRC licensees.  Two areas for which the NRC is currently developing or assessing the need for interim guidance include:  (i) subsurface investigations and (ii) discrete radioactive particles.  The NRC staff is issuing additional guidance or other information for these two topics to allow members of the public to participate in the process.  Opportunities for public engagement in the guidance development process are listed in the Recent and Upcoming Meetings and Activities section.  Historical and recent information related to subsurface and discrete radioactive particle surveys are listed in the sections below to provide context for the issue. Staff will consider the historic record on these topics in developing interim guidance or other type of communication which will ultimately be folded into the next revision of NUREG-1757.

Subsurface Investigations

Many complex materials and decommissioning sites undergoing decommissioning have significant levels of residual radioactivity in subsurface soils and groundwater.  The Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) addresses radiological surveys for surface residual radioactivity; however, federal guidance does not currently address characterization and radiological surveys for the subsurface.  Subsurface soils are more difficult to access, and traditional scanning techniques are ineffective at measuring residual radioactivity at depth.  Given challenges and limitations with subsurface surveys, methods to leverage existing data and optimize subsurface survey design will be proposed.  Potential tools currently available to assist with remedial and final status survey decisions will be described.  Additionally, the NRC has contracted out with Pacific Northwest National Laboratory to scope out additional tools for implementation in Visual Sample Plan to assist with subsurface survey design and data analysis to support decommissioning decision-making. The following table provides historical and more recent information related to the topic that will be considered in developing the draft interim guidance.

Document No./Title Date Notes
NUREG/CR-7021, "A Subsurface Decision Model for Supporting Environmental Compliance" January 2012 Preliminary technical basis for design of subsurface surveys using the Spatial Analysis Decision Assistance (SADA) code.
NUREG-1757, Volume 2, Rev. 2, "Consolidated Decommissioning Guidance, Characterization, Survey, and Determination of Radiological Criteria: Draft Report for Comment" December 2020 The draft for public comment was issued in December 2020.  New subsurface survey and dose modeling guidance was included in Appendix G and J.
NUREG-1757, Volume 2, Rev. 2 Public Meeting
Presentation Slides (ML21057A335)
Public Meeting Notice (ML21057A335)
March 2021 A public meeting was held on March 15, 2021, to discuss updates to Volume 2 of NUREG-1757, as well as listen to comments on the draft document. The March 15, 2021, meeting summary and transcript can be found here:
2021 Subsurface Soils Workshop
Research Information Letter 2021-12 
Subsurface Soil Surveys Public Workshop - DAY 1
Subsurface Soil Surveys Public Workshop - DAY 2
July 14-15, 2021 The NRC held a workshop in July 2021 that was attended by over 160 participants.  Topics included use of geostatistical methods for complex reactor and material decommissioning; dose modeling and elevated area considerations for subsurface soils; and challenges associated with surveys of open excavations. Additional information can be found here: ML21208A206.
2022 Subsurface Investigations Workshop
Subsurface Investigations Public Workshop - Video
May 11, 2022 The NRC held a workshop on May 11, 2022, that was attended by approximately 130 participants. Discussion topics included geospatial approaches to optimize subsurface survey design and support decommissioning decision-making; innovative technologies (e.g., electrical resistivity tomography) for subsurface characterization; and lessons learned and case studies related to subsurface projects. See detailed meeting agenda, transcript and presentations at ML22117A070.
Technical Letter Report on characterizing and evaluating subsurface residual radioactivity (authored by NRC contractor: SC&A Inc.) Final expected July/August 2022 Draft technical basis document (April 2022)

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Discrete Radioactive Particles

NRC is also considering the need for interim guidance related to radiological survey considerations for detection of discrete radioactive particles (DRPs), as well as methods to evaluate the potential dose or risk associated with exposure to DRPs.  Lack of control of DRPs has been an issue for some decommissioning sites seeking unrestricted release.  DRPs may be anticipated as part of decontamination and decommissioning activities, although some activities have higher potential of DRP generation compared to others.  Guidance is available for isolation and ventilation procedures adequate for operations with the potential for DRP generation.  Licensees should be cognizant of potential activities that could generate DRPs and have a program in place to control DRP to avoid issues with assessing the presence and risk significance of DRPs at the time of license termination.  

The NRC staff are in the process of evaluating existing guidance and other information sources, which will be considered in making a decision on the need for draft interim guidance or other type of communication.  Public meetings or workshops are planned for late 2022 to discuss this topic. A historical listing of references is provided below.  Some references provide a compendium of information and represent various viewpoints and positions. While NRC is not endorsing any particular reference or viewpoint listed below, a comprehensive review of the literature is being performed to help reach a decision on the best path forward with respect to guidance development.  The NRC staff are also considering licensee provided information on discrete radioactive particles, as the information is submitted.

Document No./Title Date Notes
ICRP Publication 23, Report of the Task Group on Reference Man 1975 Comprehensive work on reference male and female, including data on mass of various organs, chemical composition of the body, and various tissue and physiological data.  The report is supplemented and amended by ICRP Publication 89.
NUREG/CR-0130, Vol. 1, Technology, Safety and Costs of Decommissioning a Reference Pressurized Water Reactor Power Station June 1978 Among other decommissioning topics, provides data on concentrations of activation products associated with concrete biological shield at pressurized water reactors.
ICRP Publication 30, Limits for Intakes of Radionuclides by Workers 1979 Recommends Annual Limits for Intakes of radionuclides by workers and much of the biokinetic information forms the basis of newer dosimetry available in ICRP 60, and dose coefficients in ICRP Publications 68, 69, 71, and 72.
NUREG/CR-3474, Long-lived Activation Products in Reactor Materials August 1984 Provides results of sampling stainless steel, vessel steel, and concrete to develop a database of activatable major, minor, and trace elements to determine possible nuclear reactions that could lead to long lived activation products.  Estimated concentrations of activation products in reactor internals, core shrouds, core barrels, thermal pads, and vessel cladding are provided.
Information Notice No. 86-23, Excessive Skin Dose Due to Contamination with Hot Particles April 1986 Discusses skin contamination incidents from hot particles at reactor sites and follow-up protective measures.
Information Notice 87-39, Control of Hot Particle Contamination at Nuclear Power Plants August 1987 Discusses hot particle events, fuel degradation, and lack of controls during fuel reconstitution and associated lessons learned.
Collection and Characterization of Aerosols from Metal Cutting Techniques Typically Used in Decommissioning Nuclear Facilities, Am. Ind. Hyg. Assoc. J. 48:11, 922-932 November 1987 Provides information on aerosol production rate, shape, and size for various metal cutting tools.
Information Notice 90-33, Sources of Unexpected Occupational Radiation Exposures at Spent Fuel Storage Pools May 1990 Discusses potential sources of radiation exposure from spent fuel storage pools.
Enforcement Policy Regarding Occupational Doses from ‘Hot Particles’, Policy Statement (55 FR 31113)   July 1990 Enforcement policy for skin dose from discrete radioactive particles.
Information Notice 90-48, Enforcement Policy for Hot Particle Exposures August 1990 Discusses enforcement discretion for skin exposure from hot particles.
Enforcement Policy for Hot Particle Exposure – Answers to Three Questions November 1990 Clarifies statements made in IN 90-48.
Discrete radioactive particles at nuclear power plants; Prevention, mitigation and control, Radiation Protection Measurements, Vol. 8, No. 5, p. 65-79 1991 Provides radiological safety professionals at nuclear power plants with information on the prevention, mitigation, and control of discrete radioactive particles. 
Characterization of Aerosols from Dismantling Work of Experimental Nuclear Power Reactor Decommissioning, J. Aerosol Sci., Vol. 22, Suppl. 1, p. S747-S750 September 1991 Looks at aerosol generation for stainless steel pipe segmentation with mechanical vs. thermal cutting tools and mitigative measures.
Annals of the ICRP, Publication 66.  Human Respiratory Tract Model for Radiological Protection 1994 The report describes a revision to the model used in ICRP Publication 30 to calculate radiation doses to the respiratory tract of workers from intake of airborne radionuclides. 
Biokinetics of Nuclear Fuel Compounds and Biological Effects of Nonuniform Radiation, Environmental Health Perspectives, Vol. 103, No. 10 October 1995 Data on hot particles, including sources, dosimetry, and human exposure are discussed. The biokinetics of insoluble nuclear fuel compounds in the gastrointestinal tract and respiratory tract are reviewed, and short- and long-term biological effects of nonuniform alpha- and beta-irradiation on the gastrointestinal tract, lungs, and skin are discussed.
NUREG/CR-5884, Vol. 1, Revised Analysis of Decommissioning for the Reference Pressurized Water Reactor Power Station November 1995 Provides information regarding decommissioning of pressurized water reactors including ventilation controls.
EPRI Report No. NP-5969, Problem Assessment of Discrete Radioactive Particles August 1998 A survey was conducted to gather existing information and to determine the incidence of DRPs in operating nuclear power plants, methods of detection, locations, isotopic analyses, and other relevant data.
EPRI Report No. 104125, Industry Experience with Discrete Radioactive Particles  August 1994 Presents operating nuclear power plant survey results with regard to prevalence and nature/type of DRPs identified.
NCRP Report No. 130, Biological Effects and Exposure Limits for “Hot Particles” 1999 This report considers “hot particles” on and off the skin, in the eye and ear, and those that might be inhaled or ingested.  Also provides information on characteristics of DRPs.
SECY-98-117, Shelwell Services, Inc., Risk Assessment May 1998 Provides risk assessment approach that considers the likelihood and consequences of exposure to discrete radioactive particles.
DOE/EM-0392, Liquid Nitrogen Cooled Diamond-Wire Concrete Cutting December 1998 Provides aerosol data for diamond-wire cutting.
DOE/EM-0527, Diamond Wire Cutting of the Tokamak Fusion Test Reactor Vacuum Vessel   April 2000 Provides aerosol data for diamond-wire cutting.
HCET-2000-D052-001-04, Size Distribution and Rate of Production of Airborne Particulate Matter Generated During Metal Cutting January 2001 The study presents data regarding the metal cutting rate, particle size distribution, and generation rate for different cutting tools and metals.
Regulatory Analysis of Revisions to 10 CFR 20: Unified Skin Dose Limit October 2001 Regulatory analysis to support skin dose rulemaking related to discrete radioactive particles.
Information Notice 2002-03, Highly Radioactive Particle Control Problems During Spent Fuel Pool Cleanout January 2002 Discusses issues associated with evaluation and control of radioactive particles generated during removal of material from spent fuel pools prior to shipping the material for offsite disposal.
Regulatory Issue Summary 2002-10, Revision of the Skin Dose Limit in 10 CFR Part 20 July 2002 Provides information on the change in regulatory dose limit for the skin in 10 CFR Part 20, effective June 4, 2002.
Exhibit CY-5-Panel 1 - Panel Attachment 4: Health Physics Department, Technical Support Document, HP Number BCY-HP-0125, Rev. 0: Dose Estimate for an Ingested Particle December 2002 Provides a dose estimate for an ingested particle in Haddam Neck hearing.
Doses and Risks from the Ingestion of Dounreay Fuel Fragments, Radiation Protection Dosimetry, Vol. 105, Nos 1-4, 49-54, February 2003 MCNP calculation of dose to the lower large intestine of Dounreay fuel fragment particles found in a marine environment
Haddam Neck - Exhibit 4 (CY Exhibit 5-PANEL 1) - Panel Attachment 4 - Health Physics Department Technical Support Document - Dose Estimates for Ingested Particle March 2003 Ingestion dose calculation from hot particles at Connecticut Yankee
Haddam Neck - Exhibit 17 (CY Exhibit 5-GEC): Letter to Mr. Gad from G. Chabot regarding dose from hot particle in Extrathoracic Region ET2 of Respiratory Tract March 2003 Dose calculations for 10 um hot particle to extrathoracic region of the respiratory tract
EPRI Report No. 1002823, Implementing the EPRI Effective Dose Equivalent (EDE) Methodology for Discrete Radioactive Particles on the Skin October 2004 Discusses effective dose equivalent (EDE) method to calculate hot particle exposures.
RPD-EA-9-2005, Public Health Implications of Fragments of Irradiated Fuel: Module 3: The Likelihood of Encountering a Fuel Fragment on Sandside Beach June 2005 Provides information on the number of fuel fragments found on Sandside Beach and activities and likelihood of individuals coming into contact with such fragments.
Hot Particle Dosimetry and Radiobiology – Past and Present, J. Radiol. Prot. Vol. 27, No. 3A, p. A97-109 August 2005 Hot particle dosimetry, considerations, and changes over time.
Spatially-Dependent Measurements of Surface and Near-Surface Radioactive Material Using In situ Gamma Ray Spectrometry (ISGRS) for Final Status Surveys, Prepared for US NRC in support of RFTA-06-010 November 2006 Evaluates the ability of in-situ gamma ray spectrometry for detection of discrete radioactive particles
Techniques Employed for Detection of Hot Particle in the Marine Environment, J. Radiol. Prot., Vol. 27, No. 3A, A39-A44 August 2007 Survey methods for hot particles in a marine environment near the Maine Yankee nuclear plant.
Letter from S. Redeker (Sacramento Municipal Utility District) to J. Hickman (NRC), dated April 2, 2007, Re: Response to NRC Request for Additional Information April 2007 Among other topics, the presence, programs to control, detectability, and assessment of dose from discrete radioactive particles is discussed.
DTRA-TR-09-16, Radiation Doses to Skin from Dermal Contamination October 2010 Presents a methodology to estimate doses to skin from dermal contamination due to a uniform deposition of airborne radioactive material in specific regions of the body.
ICRP Publication 130, Occupational Intakes of Radionuclides:  Part 1 2015 Replaces ICRP Publications 30 and 68 to provide revised dose coefficients for occupational intakes of radionuclides by inhalation and ingestion using the Human Alimentary Tract Model (ICRP Publication 100) and a revision of the Human Respiratory Tract Model (ICRP Publication 66) that accounts for more recent data.  Information is provided on absorption into blood following inhalation and ingestion of different chemical forms of elements and associated radioisotopes.
ICRP Publication 134, Occupational Intakes of Radionuclides:  Part 2 2016 The 2007 recommendations of the ICRP introduced changes that affect calculation of effective dose, and implied a revision of the dose coefficients for internal exposure, published previously in ICRP 30 and 68.  The present publication provides data for the following elements: hydrogen (H), carbon (C), phosphorus (P),sulphur (S), calcium (Ca), iron (Fe), cobalt (Co), zinc (Zn), strontium (Sr), yttrium(Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), and technetium (Tc).
NUREG/CR-7227, US Commercial Spent Nuclear Fuel Assembly Characteristics: 1968-2013 June 2016 Documents a survey of all US spent nuclear fuel assemblies discharged from commercial reactors between the years of 1968 to 2013.  Results include total activity, decay heat, photon emission, neutron flux, gamma heat, and plutonium content, as well as concentrations for 115 significant nuclides.
ICRP Publication 137, Occupational Intakes of Radionuclides:  Part 3 2017 See ICRP 134.  The third publication in the series provides data for the following elements: ruthenium (Ru), antimony (Sb), tellurium (Te), iodine (I), caesium (Cs), barium (Ba), iridium (Ir), lead (Pb), bismuth (Bi), polonium (Po), radon (Rn), radium (Ra), thorium (Th), and uranium (U).
NUREG-1700, Revision 2, Standard Review Plan for Evaluating Nuclear Power Reactor License Termination Plans April 2018 NRC staff guidance on conduct of safety reviews of nuclear power reactor license termination plans.
ICRP Publication 141, Occupational Intakes of Radionuclides:  Part 4 2019 See ICRP 134.  The fourth publication in the series provides data for the following elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), actinium (Ac), protactinium (Pa), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), and fermium (Fm).
NUREG-1507, Revision 1, Minimum Detectable Concentrations with Typical Radiation Survey for Instruments for Various Contaminants and Field Conditions August 2020 The document describes and quantitatively evaluates the effects of various factors on the detection sensitivity of commercially available portable field instruments being used to conduct radiological surveys in support of decommissioning.
Inspection Procedure 83750:  Occupational Radiation Exposure at Permanently Shutdown Reactors January 2021 Discusses inspection objectives to determine whether licensee performance (i) ensures adequate protection of worker health and safety from exposure to radiation or radioactive material at permanently shut-down reactors, and (ii) evaluate whether the licensee adequately identified problems and implements appropriate and timely corrective actions related to occupational radiation safety.  The inspection procedure addresses reviews of shallow dose equivalent records related to incidents involving DRPs, as well as airborne and contamination controls.
Using VARSKIN for Hot Particles Ingestion Dosimetry Evaluation 2022 International Agreement Report, coming soon

Lessons Learned

Lessons learned can be found at ML20052C815, "Lessons learned and Questions and Answers to Clarify Decommissioning and License Termination Guidance and Plans". Most of these lessons learned were folded into the current revisions to NUREG-1757, Volumes 1 and 2. Future lessons learned will be captured in this section to provide a basis for future guidance development.

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Page Last Reviewed/Updated Monday, June 06, 2022