Information Notice 2024-01, Minimization and Control of Contamination Involving Discrete Radioactive Particles at Decommissioning Facilities
| ML23195A074 | |
| Person / Time | |
|---|---|
| Issue date: | 02/09/2024 |
| From: | Russell Felts, Kevin Williams NRC/NMSS/DMSST, NRC/NRR/DRO/IOEB |
| To: | |
| References | |
| IN-24-001 | |
| Download: ML23195A074 (9) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
WASHINGTON, DC 20555-0001
February 9, 2024
NRC INFORMATION NOTICE 2024-01: MINIMIZATION AND CONTROL OF
CONTAMINATION INVOLVING DISCRETE
RADIOACTIVE PARTICLES AT DECOMMISSIONING
FACILITIES
ADDRESSEES
All holders of and applicants for an operating license or construction permit for a nuclear power
reactor issued under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic
Licensing of Production and Utilization Facilities, including those that have permanently ceased
operations and certified that fuel has been permanently removed from the reactor vessel.
All holders of and applicants for a power reactor combined license, standard design approval, or
manufacturing license under 10 CFR Part 52, Licenses, Certifications, and Approvals for
Nuclear Power Plants. All applicants for a standard design certification, including such
applicants after initial issuance of a design certification rule.
All holders of and applicants for an independent spent fuel storage installation license under
10 CFR Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related Greater Than Class C Waste.
All holders of, and applicants for, a fuel facility license under 10 CFR Part 70, Domestic
Licensing of Special Nuclear Material.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform
licensees of recent challenges involving detection and contamination control of hot particles, commonly referred to as discrete radioactive particles (DRPs),1 during plant operations and
decommissioning. This communication is intended to reinforce compliance with the
10 CFR Part 20, Subpart F, Surveys and Monitoring, 10 CFR 20.1501 General requirement
to use appropriate survey practices to detect and in coordination with 10 CFR 20.1406
1 DRPs are typically called hot particles, which have been described as particles less than 1 mm in any
dimension, of high activity, and generally insoluble in water. Particles or objects greater than 1 mm that
approximate point sources when field scanning or measuring are also addressed in this discussion due to
their similarities to DRPs especially in detection and potential risk-significance. Examples of DRPs are
fuel fleas, activated metal shavings from reactor component wear or segmentation, and activated
bioshield concrete fragments from segmentation. Minimization of contamination, reduce the spread of residual radioactivity. Residual
radioactivity may include hot particles and, therefore, licensees are reminded of the importance
of documenting issues important to decommissioning in the reporting and recordkeeping files
required by 10 CFR 50.75, Reporting and recordkeeping for decommissioning planning.
Similar requirements for subject addresses are contained in 10 CFR 72.30, Financial
assurance and recordkeeping for decommissioning and 10 CFR 70.25, Financial assurance
and recordkeeping for decommissioning. These efforts will help mitigate future challenges
associated with the survey and remediation of contaminated areas at decommissioning sites
and potential delays in license termination. The NRC expects that recipients will review the
information for applicability to their facilities and consider actions, as appropriate, to avoid
potential challenges with mitigation and remediation. However, the information contained in this
IN are not NRC requirements; therefore, no specific action or written response is required.
BACKGROUND
The regulations at 10 CFR 20, Subpart F, require that each licensee conduct surveys in areas, including the subsurface, that (1) are necessary for compliance with regulations and (2) are
deemed reasonable under the circumstances to assess the magnitude and extent of radiation
levels, concentrations or quantities of residual radioactivity, and the potential radiological
hazards associated with the detected radiation levels and residual radioactivity. Additionally, according to 10 CFR 20.1201(a)(2)(ii), licensees are required to control the occupational dose to
individual adults to a shallow-dose equivalent of 50 rem (0.5 Sv) to the skin of the whole body or
to the skin of any extremity. The occupational skin dose limit applies to that dose from exposure
to hot particles or DRPs during operations. If these radioactive particles are not properly
controlled and dispositioned during operations, they may become a residual radioactivity
concern at the time of decommissioning of the facility with potential public exposure concerns
after license termination.
During plant operations and major component replacement outages, hot particles are likely to
be present and additional surveys and controls are commonly instituted. Addressing
contamination in a timely manner will prevent both the spread of contamination and exposure to
residual radioactivity. Regular surveys of areas likely to have hot particles are typically
conducted with the intent to control, identify, and remediate contamination at the source.
Controlling and minimizing the spread of contamination are vital to prevent productivity and
efficiency losses during decommissioning.
The regulation at 10 CFR 50.75(g)(1) requires that licensees maintain a record of spills or other
unusual occurrences involving the spread of contamination in and around a facility or site.
These records include any known information on the identification of involved nuclides and their
quantities, forms, and concentrations. These records may be limited to instances when
significant contamination remains even after any clean-up procedures are used or when there is
a reasonable likelihood that contaminants may have spread to inaccessible areas or porous
materials and apply during decommissioning.
In the 1997 final rule on decommissioning planning (76 FR 35511), the NRC amended its
regulations to improve decommissioning planning by establishing a new regulation at
10 CFR 20.1406, Minimization of contamination, and amending the regulation in 10 CFR 20.1501(a). These regulations state that the surveys of areas include the subsurface to
evaluate residual radioactivity. As described in the 1997 final rule, residual radioactivity that is
significant for decommissioning planning is a quantity of radioactive material that would require
remediation during decommissioning to meet the unrestricted use criteria of 10 CFR 20.1402, Radiological criteria for unrestricted use. Consistent with 10 CFR 50.75(g) requirements, licensees maintain records of spills or other unusual occurrences involving the spread of
contamination in and around the facility, equipment, or site until the license is terminated. The
regulation applies to events that occur while the plant is operating and during decommissioning.
The requirement outlined in 10 CFR 20.1501(b) is associated with the existing 10 CFR 50.75(g)
provisions in requiring that survey records of subsurface residual radioactivity are kept with
records important for decommissioning.
In 2008, the NRC issued Regulatory Guide 4.21, Minimization of Contamination and
Radioactive Waste Generation: Life Cycle Planning, and, in 2012, issued Regulatory
Guide 4.22, Decommissioning Planning During Operations. Both Regulatory Guides are
focused on contamination control during design and operations to facilitate future
decommissioning. This guidance provides a threefold contaminant management philosophy
during active decommissioning: (1) prevention of unintended releases, (2) early detection, if
there is unintended release of radioactive contamination, and (3) prompt assessment to support
a timely and appropriate response.
While DRPs in the outside environment (outside buildings or containment) are not specifically
addressed in NRC guidance during decommissioning, reviewing the lessons learned below, employing the above containment management philosophy, having a good understanding of
NUREG-1575, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM)
guidance and maintaining good surveying practices could prevent delays in decommissioning.
MARSSIM provides detailed guidance on planning, conducting, evaluating, and documenting
building surface and surface soil final status radiological surveys for demonstrating compliance
with dose or risk-based regulations or standards. MARSSIM focuses on the demonstration of
compliance during the final status survey following scoping, characterization, and any necessary
remedial actions. The NRC staff is currently determining the appropriate guidance to address
this form of contamination throughout decommissioning.
DISCUSSION
As more plants have entered decommissioning, the NRC noted inconsistencies in the types of
events entered in the 10 CFR 50.75(g) file and the level of detail documenting spill or leak
events at decommissioning sites. In accordance with 10 CFR 50.75(g), licensees are required to
document significant residual radioactivity that remains or when there is reasonable likelihood
that contaminants may have spread to inaccessible areas. These records combined with
characterization information such as the involved nuclides, quantities, forms, and concentrations
are important to maintain so that NRC staff can review how the licensee conducted surveys and
assessed the dose from material left in place. Licensee understanding of the characteristics and
location of residual radioactivity for final status surveys is vital to addressing the impacts of
inaccessible areas. A site may be challenged with demonstrating compliance with the
radiological criteria for license termination if contamination is not resolved before a final status
survey (FSS) begins. As discussed in the Examples of Lessons Learned section, demolition and decommissioning
activities can generate or release DRPs that were unknowingly present in equipment or
components being removed or dismantled as part of the decommissioning process. The
presence of DRPs could result from inadvertent or unintentional contamination of soil during
waste loading or from a lack of sufficient ventilation and containment during waste handling
operations.
Consistent with 10 CFR 50.82, Termination of license, specific information is required in a
License Termination Plan (LTP). As described in NUREG 1700, Standard Review Plan for
Evaluating Nuclear Power Reactor License Termination Plans, a description of the techniques
that will be employed to remove or remediate surface and subsurface soils, groundwater, and
surface water and sediments should be contained in the LTP. DRPs may become an issue even
at sites with no history of fuel failure or releases during operation, because DRPs may be
produced and released during the segmentation or dismantling of reactor vessel internals and
other contaminated piping, equipment, or components. Often, the Historical Site Assessment
and site characterization activities are completed well in advance of when the LTP is submitted
to the NRC. In some cases, site characterization occurs prior to many of the segmentation and
dismantling activities that may contribute to the spread of contamination. In multiple cases, contamination events have occurred after the LTP license amendment request is submitted to
the NRC and, in some cases, after the LTP is approved.
The NRC may need to perform additional work to evaluate the adequacy of the licensee's
compliance with regulations when uncertainties arise regarding the appropriateness of licensee
surveys. This may include requests for additional information and potential license amendment
requests to incorporate the appropriate survey techniques or dose considerations into the LTP.
Examples of Lessons Learned
During active decommissioning, radioactive cross-contamination of site soil involving DRPs has
occurred at reactor facilities due to material movement from buildings, debris piles or stockpiles, or waste containers. There have been instances of untimely or inadequate surveys conducted
after cross-contamination involving DRPs. Discovery of DRPs during decommissioning
operations and during confirmatory surveys resulted in increased regulatory oversight licensee
effort to assess the presence and risk significance of the DRPs.
Below are summaries of recent DRP issues:
Example 1
Licensee surveys at a decommissioning nuclear power reactor site detected DRPs near
containment hatch openings and surrounding survey units. The surveys were to be used for
FSS to show license termination compliance within the power block land area. The DRPs, in the
form of fuel fragments and metal shavings generated during reactor internal segmentation
activities, were thought to have been released from containment and deposited on soil. The
release occurred due to insufficient negative pressure during the movement of potentially
contaminated equipment and large components through enlarged equipment hatches of
containment buildings before the erection of waste loadout tents. The DRPs could have been
dislocated by rain or wind, or during rigging activities from packaged waste during loading. Without appropriate use of safety and radiological control protocols, it is possible for DRPs to be
dislocated from the material during the removal process or waste liner transfers to licensed
casks. DRP clean-up was achieved through a combination of FSS and a confirmatory survey for
the area.
Example 2
When a liner was loaded into an overpack, contamination on the outside of the inner liner was
spread to the ground and cask, then spread further when the shipping cask was moved to
another area of the site. The licensee determined that the contamination was spread by the
action of inserting the liner into the overpack. Contamination on the inner liner had dried over a
long storage period and was therefore more easily dispersible than normal when the inner liner
was loaded into the overpack. In addition, high ambient radiation levels hindered the ability to
perform a thorough survey. A timely survey after the packing of the inner liner could have
prevented the spread of contamination beyond the localized area. DRP clean-up was achieved
through a combination of FSS and Confirmatory Survey.
Example 3
Concrete debris that was determined to be free of residual radioactive material was in an area
that had previously undergone an FSS. Concrete debris that had been cleared by surveys prior
to demolition was being staged for removal from the site. The concrete was consolidated in
temporary staging areas and may have been moved between staging areas. Some of these
staging areas were placed on units that had undergone FSS. Subsequently, DRPs were found
in these previously surveyed land areas. The licensee was not able to determine where the
DRPs came from or how they were transported. The DRPs may have resulted from building
demolition or from subsequent movement of the concrete from the building demolition area into
the areas previously determined to be free of residual radioactive material. These practices
were not in compliance with the licensees isolation and control measures. DRP clean-up was
achieved through a combination of FSS and Confirmatory Survey.
PAPERWORK REDUCTION ACT STATEMENT
This IN does not contain new or amended information collection requirements that are subject to
the Paperwork Reduction Act of 1995 (44 U.S.C. 10 CFR 3501 et seq.). Existing requirements
were approved by the Office of Management and Budget (OMB) under approval control
numbers 3150-0009, 3150-0011, 3150-0014, 3150-0132, and 3150-0151.
PUBLIC PROTECTION NOTIFICATION
The NRC may not conduct or sponsor, and a person is not required to respond to, a collection
of information unless the document requesting or requiring the collection displays a currently
valid OMB control number.
CONTACT
S
This IN requires no specific action or written response. Please direct any questions about this
matter to the technical contact listed below or the appropriate Office of Nuclear Material Safety
and Safeguards (NMSS), Reactor Decommissioning Branch, Project Manager.
/RA/
/RA/
Kevin Williams, Director
Division of Materials Safety, Security, State, and Tribal Programs
Office of Nuclear Material Safety
and Safeguards
Russell Felts, Director
Division of Reactor Oversight
Office of Nuclear Reactor Regulation
Technical Contact:
301-415-6822 E-mail: Amy.Snyder@nrc.gov REFERENCES
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NRC, Regulatory Guide 4.22, Decommissioning Planning during Operations, December 2012 (ML12158A361).
NRC, Regulatory Guide 4.21, Minimization of Contamination and Radioactive Waste
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dated July 9, 2002 (ML021860332).
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Decommissioning Activities Report, Revision 1, issued June 2013 (ML13140A038).
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Nuclear Power Reactors, Revision 2, issued July 2019 (ML110490419).
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EPIDS No. L-2023-GEN-0005 OFFICE Tech Editor
NMSS/DUWP/RDP NMSS/DUWP/RTAB
NMSS/DUWP/RDB
OCIO
NAME
JDougherty
ASnyder
CMcKenney
SAnderson
JPeralta
DCullsion
DATE
6/12/2023
7/24/2023
7/24/2023
7/272023
2/1/2024
2/1/2024 OFFICE NRR/DRO/IOEB
NRR/DRO/IOLB
NRR/DRO/IOEB
NMSS/DUWP
NMSS/DFM/IOB
NMSS/DFM/IOB
NAME
PClark
IBetts
LRegner
JMarshall
JTapp
ARivera-Varona
DATE
2/1/202
2/1/2024
2/2/2024
1/16/2024
1/23/2024
1/23/2024 OFFICE NMSS/DFM
NMSS/MSST
NRR/DRO
NAME
SHelton
KWilliams
RFelts (PMckenna for)
DATE
1/26/2024
2/8/2024
2/9/2024