ML24032A040
| ML24032A040 | |
| Person / Time | |
|---|---|
| Issue date: | 02/01/2024 |
| From: | Cynthia Barr, Gregory Chapman, Bruce Watson Division of Decommissioning, Uranium Recovery and Waste Programs, Reactor Decommissioning Branch, NRC/NMSS/DDUWP/RTAB |
| To: | |
| Shared Package | |
| ML24032A030 | List: |
| References | |
| Download: ML24032A040 (11) | |
Text
NRC Perspectives on Discrete Radioactive Particles EPRI/NEI Decommissioning Conference Oceanside, CA February 1, 2024 Bruce Watson, CHP Cynthia Barr Gregory Chapman, CHP Office of Nuclear Material Safety and Safeguards Division of Decommissioning, Uranium Recovery and Waste Programs
General Considerations DRP contamination control/
monitoring are important during both plant operations and decommissioning If a release to the environment does occur, licensees should take corrective action to identify, remediate, and document the release and results DRPs should be addressed in the License Termination Plan, prior to the time of final status survey
History
- Information Notice No. 87-39: Control of Hot Particle Contamination at Nuclear Power Plant
- Information Notice No. 90-33: Sources of Unexpected Occupational Radiation Exposures at Spent Fuel Storage Pools
- EPRI Report No. 104125, 1994: Industry Experience with Discrete Radioactive Particles
- Reg Guide 4.21, Minimization of Contamination and Radioactive Waste Generation: Life Cycle Planning (2008)
- Reg Guide 4.22, Decommissioning Planning During Operations (2012)
Discrete Radioactive Particles (DRPs) at decommissioning sites Technical issues
- DRP survey methods
- DRP dosimetry
- Skin dose
- Inhalation and ingestion dose (including localized exposures)
- Exposure scenarios 4
Nov. 2022 Workshop
- Technical presentations
- Oak Ridge Associated Universities/Oak Ridge Institute for Science and Educationradiological surveys and scan MDAs
- Renaissance Code Developmentdosimetry
- US NRCexposure scenarios
- Stakeholder proposed topics
- DRP survey expectations
- DRP exposure scenarios and pathways
- DRP dose criteria
DRP Workshop Findings
- In general, lower MDAs can be achieved with closer detector to source distances, and slower surveyor speeds.
- No public dose limits exist, but occupational ulceration dose thresholds are available.
- Various Dose Conversion Factors were calculated for various DRP material types and radionuclides.
- Likelihood of exposure can be considered in DRP dose assessments.
- Doses and qualitative arguments regarding likelihood should be presented separately (i.e., dose should not be multiplied by likelihood).
Workshop Technical Reports Three draft technical reports were discussed by NRC Contractors Estimating Scan Minimum Detectable Activities of Discrete Radioactive Particles (ML24004A133)
October 2022 (Draft)
January 2024 (Final)
Discusses survey of DRPs and provides information on calculation of scan MDAs for select radionuclides, depths and offset distances.
Issuance of Dose Coefficients (DC) for Discrete Radioactive Particles (DRPs)
(ML23136A178) and Ulcerations Threshold Recommendations (ML23136A207) technical reports.
May 2023 Renaissance Code Development (RCD) published two reports on dosimetry for discrete radioactive particles in decommissioning.
Information Notice
- Applicable to Operating and Decommissioning Reactors
- Minimization of Contamination and Contamination Control Involving Discrete Radioactive Particles at Power Reactors
- Emphasizes regulatory requirements found in
- 10 CFR 20.1501 Subpart F
- Discusses pertinent regulatory guides
- Provides lessons learned
- Expected to be issued in early 2024
Confirmatory Surveys
Interim Staff Guidance
- Staff are assessing the scope of interim staff guidance on DRP survey and dosimetry
- Staff plans to issue the ISG in late 2024
- The guidance could be included in future revisions to NUREG-1757, Volume 2, MARSSIM, or NUREG-1507.
Concluding thoughts Licensees should practice good contamination control and radiation protection practices during operations and decommissioning including:
- refueling and spent fuel pool activities
- underwater segmentation activities
- survey and monitoring (e.g., air monitors, exit surveys, confinement barriers, contamination surveys, isolation and controls, bioassay), as appropriate Promptly address releases to the environment; the ability to detect DRPs decreases in soils and vegetation Use your corrective action program and document radiological spills, DRPs and release events in your 10 CFR 50.75(g) file