ML25233A219
| ML25233A219 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 09/04/2025 |
| From: | Amy Snyder Reactor Decommissioning Branch |
| To: | |
| Shared Package | |
| ML25233A216 | List: |
| References | |
| Download: ML25233A219 (1) | |
Text
Enclosure 2 U.S. NUCLEAR REGULATORY COMMISSION
SUMMARY
OF THE AUGUST 6, 2025, PRE-APPLICATION MEETING WITH KEWAUNEE SOLUTIONS, LLC.
TO DISCUSS THE KEWAUNEE PRE-APPLICATION LICENSE TERMINATION PLAN LICENSING STRATEGY The meeting held on August 6, 2025, focused on Kewaunee Solutions, LLC (Kewaunee Solutions) licensing amendment strategy for the Kewaunee Nuclear Power Station License Termination Plan (LTP). Various members from the NRC (Nuclear Regulatory Commission) and Energy Solutions, LLC and Kewaunee Solutions participated, including project managers, branch chiefs, senior inspectors, and technical reviewers. The meeting began with introductions, where participants highlighted their roles and expertise within their respective organizations.
Kewaunee Solutions presentation (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25217A080) was led by Robert F. Yetter, III, Director, License Termination/Final Status Survey for Energy Solutions, LLC. The presentation followed the subject area chapters of a LTP as suggested by NRC guidance, Regulatory Guide 1.179, Standard Format and Content of License Termination Plans for Nuclear Power Reactors.
Kewaunee Solutions stated that their goal is to build upon lessons learned from the past LTPs that it has developed for other nuclear power plants. Also, Kewaunee Solutions indicated that the Kewaunee Nuclear Power Stations LTP would essentially follow the same technical approaches as those identified in the Fort Calhoun Station, Unit 1 LTP.
The NRC staff provided feedback and engaged in discussions about the proposed licensing strategy. Highlights of the discussion are summarized below:
Kewaunee Solutions stated that:
o The scope of the LTP would include everything but decommissioning of the Kewaunee Nuclear Power Station Independent Spent Fuel Storage Installation (ISFSI).
o Limited characterization sampling of the subsurface was conducted to a standard depth of 3 meters. The water table is at a depth of about 10-15 ft.
o The LTP will be revised to include a strategy to conduct subsurface sampling as part of continuing characterization particularly in areas where records indicate subsurface contamination could be present and near/under processing buildings where substructures will remain.
The NRC staff asked about Kewaunee Solutions subsurface strategy for remedial surveys. Kewaunee Solutions explained that they would perform core sampling, scan the cores, and chase the contamination until results show that their criteria for removal are met. The licensee plans to core
2 and potentially composite samples from the surface (0-15 cm) and in subsequent 1 m intervals in the subsurface. The NRC staff noted that Interim Staff Guidance, Regulatory Analysis for Final Interim Staff Guidance (DUWP-ISG-02) on Radiological Survey and Dose Modeling of the Subsurface to Support License Termination, July 2024, provides guidance on the level of survey needed in subsurface investigations, including survey of small excavations (small decision units) to remove infrastructure. The NRC staff stated that the subsurface sampling strategy should be included in the LTP, and it also should include how Kewaunee Solutions will address unexpected subsurface contamination and its impact on groundwater (particularly for mobile radionuclides). A preventative maintenance program for underground piping is in place at the site and, as a result, they have a lot of information about the status of these structures to include in characterization.
o The LTP would include a strategy that discusses judgmental sampling in accessible areas to ensure areas (including subsurface media) are adequately remediated to below derived concentration guideline levels (DCGLs).
The NRC staff noted that such an approach is consistent with As Low as Reasonably Achievable (ALARA) and it should be noted in the LTP as part of the applying ALARA strategy.
o Most of the underground piping will remain at the site and be hydrolazed, surveyed with pipe detectors, and plugged/filled as needed to ensure isolation and control. If small excavations of materials are needed, they may be refilled with soil removed from the excavation site. If so, the soil will be characterized as will be discussed in the LTP. If contaminated materials are excavated such that residual radioactivity could exceed the DCGLs, the excavation will be surveyed for final status survey (FSS) before being backfilled.
o Decommissioning should be completed in 2030 with license termination in 2031.
o Each group of media has its own radionuclide mix fractions, radionuclides of concern (ROCs) and DCGLs.
The NRC inquired about the data that would be used to determine relative fractions and insignificant radionuclides noting that previous reviews showed that insufficient basis was provided (e.g., use of characterization for concrete substructures to inform the key risk drivers for subsurface soils and above ground buildings). Variability in relative fractions particularly for different media should be assessed as part of continuing characterization. The clean-up criteria will be based on 25 mrem/yr plus ALARA. The NRC staff noted that much of the discussion of this topic is contained in Section 5.2.6.3. The NRC staff requested additional clarification in this section as to what would be done if the hard to detects (HTDs) are not verified as insignificant contributors (see last paragraph of 5.2.6.3).
o The Sign test would be used for statistical evaluations if needed.
The NRC staff note that MARSSIM guidance suggests that gross measurements (alpha/beta) be evaluated using the Wilcoxon Rank Sum (WRS) test comparing survey unit data to that collected from background reference media, although the Sign test has been allowed in the past.
3 Ambient background will be subtracted for above-grade building decommissioning; however, Kewaunee Solutions does not plan on subtracting natural background from its environmental media. While the LTP does mention paired measurements, the NRC staff believe this is a means of subtracting ambient background and requested that such methods for determining ambient background be outlined in the LTP.
NRC noted that in the final MARSSIM, Rev. 2 (not the draft MARSSIM, Rev. 2) yet to be released that the option to subtract average material background levels from the survey unit measurements has been eliminated.
o Dose from fill will not be determined because they plan on using offsite fill material local borrow pits that were sampled/surveyed prior to use on-site. The use of the backfill and their strategy will be explained in the LTP.
o For basement units, Kewaunee Solutions plans on using ISOCS (In Situ Object Counting Systems) scanning.
The NRC staff asked Kewaunee Solutions to explain how it will use the ISOCS to characterize or for final status survey measurements.
Kewaunee Solutions indicated that the model is based on conservative profiling of the contaminated concrete materials and can yield results in both pCi/m2 or pCi/g depending on how the efficiency model is established.
The NRC staff noted that when using ISOCS it is important to ensure that the 100 percent scanning requirement is met for Class 1 survey areas.
Kewaunee Solutions indicated that they would ensure the field of view for the ISOCS measurements would overlap and encompass 100% of the survey unit.
The NRC staff requested the LTP provide a verification method (e.g.,
during Radiological Assessments And Remedial Action Support Surveys (RASS) surveys) that small areas of elevated activity would be noted, and investigated when present, if doing ISOCS surveys of the substructures.
The licensee stated that elevated areas may not be important for the buried substructures and will provide supporting information, along with a technical basis document for different fields of view. Different Microshield models will be available for different geometries and depth of contamination including annular spaces. Kewaunee indicated that they are using a mobile ISOCS system at the site called the OSPRY that is more accurate than those used in the past at other sites that they were involved in for decommissioning.
o A towed array will be used in certain areas.
The NRC staff noted that its important to ensure Kewaunee Solutions explain the accuracy and use of the data from the towed array. Data to support final status survey must be of the appropriate pedigree as identified in the data quality objectives (DQOs).
The NRC staff noted that towed array data that is not accurate (large error bands) would be considered screening data and such data cannot be used to make final status survey decisions.
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The NRC staff also indicated that training requirements for the use of instruments should also be considered in the LTP strategy and that the technical basis for the towed array method could be submitted prior to the LTP as it could be separately evaluated and not tied to the LTP metrics.
o Each survey unit is a unit of compliance and will have a sampling plan.
The NRC staff asked how Kewaunee Solutions plans to submit the Final Status Survey Reports. Kewaunee Solutions stated it plans to submit them in phases but will have one final report that summarizes all results.
The NRC staff stated that the strategy for Final Status Survey Report submittal should be included in the LTP. The NRC staff needs to be able to confirm that all the survey areas and survey units in them have been evaluated by the licensee and whether they each meet the compliance criteria as well as the final all-pathway dose which considers all survey units.
o Groundwater will be included in the final dose compliance calculation.
The NRC staff asked Kewaunee to provide more information on the plan for obtaining inputs needed for the dose due to existing groundwater contamination as part of the LTP. Kewaunee Solutions stated that it plans to use the existing groundwater well results as measured after decommissioning is completed.
o The dose compliance scenario consists of two scenarios. First, the excavation of basement walls 3 m below ground surface will be included in Resident Farmer scenario. Second the excavation of basement walls, floors and foundations below 3 m will be included in the Industrial Use scenario. Kewaunee stated that the Bounding Building Occupancy exposure scenario will be applied to demonstrate compliance with above-grade buildings.
The NRC staff asked if this was like the approach Fort Calhoun Station, Unit 1 took in their LTP. Kewaunee Solutions indicated that it was similar.
o Less Likely But Plausible Exposure Scenarios will consider excavation below 3 meters for the resident farmer, contaminated drilling spoils brought to the ground surface (drilling through embedded piping in basement floors), and offsite disposal/recycling of excavated basement concrete walls and Containment steel liner.
o The highest percentage of dose among all the media is believed to be from the embedded piping in substructures and soils that would be left behind. Based on previous experience, due to access issues and difficulty decontaminating, embedded piping in building substructures typically contributes the most to cumulative dose.
The NRC staff stated that Kewaunee Solutions should explain in the LTP their risk drivers and rationale with respect to the all-pathway dose given that Kewaunee Solutions presentation indicated that they believe the most dose will come from the subsurface. Also, Kewaunee indicated that their underground piping characterization program is mature but most piping will be left in place. The NRC staff asked if the dose from underground piping that remains in place will be included in the all-pathway dose. Kewaunee Solutions stated that it will provide final dose
5 estimates following FSS and will include any in place underground piping in the assessment.
o The excavation scenario will be included in the LTP and it will distinguish between soil and concrete debris.
o Environmental considerations to include consultation engagement with State officials will be included in the LTP.
The NRC staff reviewed some lessons learned from past LTP reviews with Kewaunee Solutions as follows: Licensees should include the current environmental effects and the effects determination analysis for endangered species; if applicable, it is important to include any impacts on any nearby fisheries or marine sanctuaries; use of borrow material on-site even if in an non-impacted area should consider any impacts to native species; historical site assessments and consultation with the State Historical Preservation Office regarding buildings and other structures need to be considered especially if the site is approaching or over 50 years of age; and if the site in a national ambient air quality standards nonattainment area, a discussion of how decommissioning impacts the criteria pollutant(s) for which the area is in nonattainment is important.
The NRC staff concludes that the approach appears reasonable but will not make any decision until they review the submittal. The meeting concluded with Kewaunee Solutions agreeing to further engagement with the NRC staff, if needed, to address specific topics such as dose assessment and final status survey may be necessary. Both parties emphasized the importance of continued collaboration and transparent communication to ensure a successful licensing review for the Kewaunee Nuclear Power Station LTP submittal. This meeting helped clarify information for the licensee, as well as the NRC staff with the goal of being able to reduce or avoid, if possible, requests for additional information.
The NRC staff provided the members of the public participating in the meeting an opportunity to ask questions of the staff about the LTP review process or the Kewaunee decommissioning.
Mr. Robert Busch for the State of Wisconsin Department of Health Services asked the NRC staff NRC staff will require other characterization to supplement the towed array measurements.
The NRC staff stated that it would determine if the characterization is sufficient when it evaluates the Kewaunee LTP submittal.
Mr. Charles Adams of the State of Wisconsin, Department of Health Services, Radiation Protection Section asked the NRC staff if there were any NRC requirements to sample the lake bed, especially the area of the lake bed near the offsite liquid effluent discharge location because members of the public inquired about it. Mr. Adams stated that the State has sampled and evaluated the shoreline but not the lake bed. The NRC staff said that it looks at the data from the required radiological environmental monitoring program (REMP) reports as part of the LTP review and would do so for the Kewanee LTP review. The NRC staff explained that environmental surveillance is to evaluate whether radionuclides are accumulating in the environment overtime. Also, the NRC staff noted that the exposure pathway for the sediment in the lake bed would be different and less significant than other exposure scenarios. The licensee
6 noted at the meetings close that it would be available to Mr. Adams and would try to answer any questions that the State had related to their concern.