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# What's New in Decommissioning of Nuclear Facilities

On this page:
        - Recent and Upcoming meetings and activities
        - Interim Guidance Development
        - Lessons Learned

## 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 issued for public comment . Comments were addressed and the document finalized on July 19, 2022 (Revision 2). 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 reopened on December 28, 2021, for 45 days and the public comment period ended on February 11, 2022 (see 86 FR 73757). The Environmental Protection Agency’s Science Advisory Board (SAB) peer reviewed draft MARSSIM, Rev. 2.  The SAB’s comments can be found in their final report. The MARSSIM working group is currently addressing public and SAB comments on the draft report.

NUREG-1700NUREG-1700NUREG-1757NUREG-1757NUREG-1507NUREG-1507MARSSIMMARSSIM

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.

## 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.

### Discrete Radioactive Particles

Lack of control of DRPs has been an issue at some decommissioning sites seeking unrestricted release.  DRPs may be present as a result of operations and can be released as part of decommissioning activities. Additionally, certain decommissioning activities (e.g., reactor vessel segmentation) could generate DRPs and lead to release of DRPs without proper controls in place. Guidance is available for isolation and ventilation procedures adequate for operations with the potential for DRP, or hot particle, 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 and content of draft interim guidance. A public workshop was held on November 3, 2022, to discuss this topic (see links to workshop materials in the first table above) and included two presentations and a paper from NRC’s contractors on (i) calculation of scan minimum detectable activities or MDAs (Oak Ridge Institute for Science and Education or ORISE), and (ii) dose conversion factors for DRPs (Renaissance Code Development [RCD]). ORISE’s scan MDA report was published in October 2022 and is linked in the table below. The focus of the RCD work is on a recommended ulceration dose threshold for internal DRPs exposure, and development of dose coefficients or dose conversion factors primarily for stationary DRPs for the skin surface, upper respiratory tract, and gastrointestinal tract as well as for effective dose equivalent received from insoluble particles that are stationary on skin or ingested.  The RCD report is expected to be published in May 2023.

NRC also plans to develop a generic communication to address issues associated with control of DRPs/hot particles during decommissioning activities (e.g., ventilation, containment, tenting, filtering, and other controls to prevent the release of DRPs into the environment), as well as proper documentation/reporting and survey following risk-significant decommissioning activities that have the potential to release radioactivity to the environment. The intent of the generic communication is to inform licensees about how particles can be generated and become an issue, including experiences from recent power reactor decommissioning projects. Additionally, the communication will reinforce the importance of good housekeeping techniques to reduce DRPs and keep them localized during waste packaging, bioshield segmentation, reactor vessel segmentation, and other risk-significant decommissioning activities which will mitigate future DRP issues at decommissioning sites. The generic communication is planned to be issued in late-2023. The need for guidance on survey and internal dosimetry associated with DRPs in decommissioning is also being considered.

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.

## 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 Tuesday, February 6, 2024

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Page Last Reviewed/Updated Tuesday, February 6, 2024