ML24269A047

Enclosure 2, Oyster Creek Nuclear Generating Station, License Amendment Request, License Termination Plan, Pending Request for Additional Information

ML24269A047
Person / Time
Site:	Oyster Creek
Issue date:	10/04/2024
From:	Amy Snyder Reactor Decommissioning Branch
To:	Trice K Holtec Decommissioning International
Shared Package
ML24269A043	List: ML24269A046 ML24269A047 ML24269A049
References
EPID L-2024-LLA-0107
Download: ML24269A047 (1)

Text

Enclosure 2 Oyster Creek Nuclear Generating Station License Termination Plan Acceptance Review Issues Pending Requests for Additional Information (RAIs)

Site Characterization 1.

Section 5.4.3, Embedded Piping and Buried Piping of the License Termination Plan (LTP) license amendment request (LAR)(ML24214A037) indicates that buried and embedded piping may remain after decommissioning. NUREG-1700, Revision 2, Standard Review Plan for Evaluating Nuclear Power Reactor License Termination Plans, Section 2.2, Site Characterization (ML18116A124) recommends that site characterization be sufficiently detailed to determine the extent and range of radiological contamination including piping. Chapter 2, LTP Standard Review Plan and Acceptance Review, of the LTP did not include characterization data for buried and embedded piping. The LTP stated that the radionuclides of interest, levels and distribution of contamination, and chosen surrogates will be included in the final status survey (FSS) plans for piping. Expand the discussion on embedded and buried piping to include data supporting the identification of radionuclides of concern (ROCs) and insignificant contributors and the development of surrogate ratios.

2.

Survey areas included in the open land area (OLA) characterization ranged from 22,000 to 180,100 m2. Biased and/or random surface samples were collected, but the number of each varied by survey area. Gamma scans were conducted at boundaries and at each survey location. Explain the basis for (1) the number of samples, (2) the selection of random verses systematic sampling, and (3) the scan area percentage and location.

3., OCNGS (Oyster Creek Nuclear Generating Station) Historical Site Assessment (HSA), Revision 2, lists seventeen areas (pg. 226) with potentially contaminated soil, including areas of excavated soils, locations where various spills and leaks occurred, and expansion joints and cracks in the New Radwaste and Old Radwaste Buildings. Furthermore, in 1982, General Public Utilities Nuclear relocated approximately 17,000 cubic feet of contaminated soil to an area somewhere between the Low-Level Radwaste Storage Facility and the north domestic water pump house. The soil was buried in shallow trenches below a minimum of six inches of clean soil.

To characterize the subsurface soil, a total of thirteen subsurface samples were taken during the open land area characterization documented in the Enclosure 5, Oyster Creek Nuclear Generation Station Site Radiological Characterization Report, Revision 1, dated April 24, 2023 of the LTP LAR. These included samples designated as SSUB (depth of 15-30 cm) and DEP1 (depth beginning at 6 or 12 inches down to 4 feet below the surface). The samples were limited to the North Owner Controlled Area (NOCA)1 (3 dep1 samples), NOCA2 (3 dep1 samples), South Protected Area (1 ssub and 1 dep1 sample), and the Radiation Control Area (RCA) (1 ssub and 4 dep1 samples).

The limited number of subsurface samples may lead to insufficient determination of the horizontal and vertical extent of the contamination. Additionally, the characterization report does not provide a basis for the depth of subsurface sampling and the sampling methodology for the 4-foot subsurface samples. Describe any plans to do additional subsurface sampling, particularly in areas where spills and leaks and waste disposal occurred, to inform remedial action and FSS planning and further derived concentration guideline level (DCGL) development.

Site Remediation Plan (As-Low-As-Reasonably-Achievable (ALARA) Analysis) 1.

Chapter 4 of the LTP provided the details of the quantitative cost-benefit ALARA analyses to demonstrate compliance with the criterion specified in 10 CFR 20.1402, Radiological Criteria for Unrestricted Use. The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the licensees calculations in the ALARA analysis and identified the several issues.

The generic ALARA analysis uses only Cesium-137 rather than all the dose significant Radionuclides of Concern (ROCs). The ALARA analysis should include all dose significant ROCs to be consistent with recommendations in NUREG-1757, Consolidated Decommissioning Guidance, Volume 2, Revision 2, Appendix N, ALARA Analysis (ML22194A859).

During the staff review of the ALARA calculations, applying equations from Appendix N of NUREG-1757, errors were identified in the inflation of the statistical monetary value of a life (VSL) and subsequent calculations inclusive of this value (CostACC, CostTF, and CostT). Additionally, the CostT for the building material evaluation was not consistent throughout the LTP and the CostT for the soil evaluation was incorrect.

Revise the calculations to include the correct value for VSL and resolve inconsistencies.

The LTP Table 4.1, Parameter Values for Use in the ALARA Analysis specifies the use of a discount rate of 0.07 per year for the building structure evaluation and 0.00 per year for the soil. NUREG-BR-0058, Regulatory Analysis Guidelines of the U.S.

Nuclear Regulatory Commission, Revision 5 (ML17100A480) recommends that a sensitivity analysis for discount rate be conducted, including no discount. Provide a sensitivity analysis of the discount rate and a justification for selection of the final rate.

The generic ALARA calculation used values of 1 m3 and 1 m2 for the estimated waste volume and survey unit area, respectively. Most remediation occurs over a survey unit area larger than 1 m2 and resulting waste volumes are significantly larger than 1 m3. Revise the ALARA analysis to reflect the actual area and volume of the proposed area to be remediated. Note it is considered ALARA pursuant to the requirements of 10 CFR 20.1402 to remediate an area of 1 m2, since this is such a small area.

Final Status Survey 1.

Add information to the LTP summarizing the dose significant ROCs and renormalized mixture fractions by area and media to clarify which radionuclides are considered for detailed analysis during final status surveys.

2.

A process for determining surrogate ratios used to account for hard to detect (HTD) radionuclides is absent from the LTP. Supplement the discussion to include:

Sample number and selection for the determination of ratios, including the method for addressing samples with results less than minimum detectable concentration (MDC)

The basis for the surrogate ratios (e.g., average, maximum, 95 percentile)

The application of ratios during direct, scanning, and in situ object counting system (ISOCS) surveys Plans for the verification of derived surrogate ratios throughout the FSS process.

Provide a priori surrogate ratios developed for each media. The alternative to surrogate ratios is to analyze all samples for the full suite of radionuclides in Table 5-2, OCNGS Site-Specific Radionuclides of Concern of the LTP.

3.

According to Section 2.3.1, Open Land Area Soil Sampling and Scanning, 10% of all soil samples were sent offsite for analysis of the full suite of radionuclides. Later, in Section 5.2.7.6, Deselection of Insignificant Contributor Radionuclides, the LTP committed to ensuring that HTDs were verified as insignificant contributors by analysis of at least 5% of soil, concrete, and groundwater media for the full suite of radionuclides.

The percentage of samples submitted for HTD analysis during the initial characterization and those used for verification of insignificant contributors (ICs) are inconsistent. Mixture fractions can be impacted by remediation activities, which requires that enough samples be collected and analyzed for the full suite of radionuclides during final status survey to verify ICs. Justify that number of FSS samples selected for IC verification is sufficient to provide reasonable assurance that ICs have not become dose significant. In the LTP, include a discussion on the verification of surrogate ratios, including the number of samples that will be analyzed for HTDs.

4.

Equation 5-7, used to calculation operational DCGLs (DCGLOPs), includes a term representing the a priori dose fraction for a specific media. The LTP does not include a priori dose fractions for each media based on results from process knowledge, site characterization, and the extent of the planned remediation, and the basis for their selection. Provide a priori values in the LTP to support the NRC staff review of DCGL applications. Delineate when the base case DCGL and operational DCGL are used in the determination investigation levels and actions, surrogate DCGLs, and gross activity DCGLs.

5.

Section 5.2.6., Reference Background Areas of the LTP acknowledges background reference areas (BRAs) are required for application of the Wilcoxon Rank Sum (WRS) test, however, the LTP does not provide survey plans for these areas. Describe in greater detail the radiological survey and sampling methodology for BRAs. Identify areas selected as BRAs and provide radiological survey results obtained for these areas.

6.

Section 5.2.6 of the LTP discussed the use of paired observations with the subsequent application of the Sign Test to account for background in materials. The LTP proposed subtraction of ambient background versus use of background materials. The intent of pair observations is to pair the survey measurement in the survey unit with an observation on a suitable reference material per NUREG-1505, A Nonparametric Statistical Methodology for the Design and Analysis of Final Status Decommissioning Surveys, Rev. 1, Section 12.3, Use of Paired Observations for Survey Units with Many Different Backgrounds (ML061870462). Identify background materials and justify their selection as a suitable background material, if used in paired measurements. Explain the statement, If paired observation is performed, the sigma value used accounts for the variability of the material background. If the survey plan is using ambient background subtraction rather than background material measurements, explicitly state this. Identify the background subtraction approach to be used in other media such as piping.

7.

NUREG-1757, Vol. 2, Rev. 2, Section J.1.1, Buried Radioactive Material or Subsurface Soil Contamination requires that licensees demonstrate that the cover or fill materials contain no radioactive contamination. If potentially contaminated fill materials are used (e.g., reuse of rubblized concrete from the site as fill), the licensee must adequately survey the materials before reusing them for debris and consider the dose contributions of residual radioactivity present in fill materials. Describe the (1) survey and sampling method for concrete rubble and soil used as backfill and (2) the process for verification that isolation and controls have prevented recontamination of stockpiled soils.

8.

Section 5.1.7, Regulatory Guidance of the LTP, listed the guidance documents committed to by the licensee. NUREG-1576, Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP), Volumes 1 and 2 (ML042310547 and ML042310738, respectively)and NUREG-1575, Supplement 1, Multi-Agency Radiation Survey and Assessment of Materials and Equipment Manual (MARSAME)

(ML090260577) are excluded from this list. MARSAME supplements MARSSIM providing information on planning, conducting, evaluating, and documenting radiological disposition surveys for the assessment of materials and equipment. The LTP indicated that the onsite laboratory programs were not maintained under the MARLAP program but were compliant with the guidance in NUREG-1575. MARSSIM defers detailed discussions of laboratory sample analysis to MARLAP, which provides guidance designed to help ensure radioanalytical data quality. MARLAP supports data collection activities including site characterization, site clean-up and compliance demonstration, decommissioning of nuclear facilities, remedial actions, environmental site monitoring, background studies, and waste management activities. Justify the exclusion of these documents, which provide guidance for release of equipment and materials and FSS planning, implementation, and data assessment. The justification should explain how the alternative approach to release of equipment and materials meets the objectives of the guidance.

9.

Chapter 5, Final Status Survey Plan, of the LTP did not include a Section on subsurface soil sampling, sampling of subsurface soils below structure basement foundations, and volumetric sampling of sediments and surface water. The HSA contained a list of potentially contaminated soils, including areas where spills and leaks occurred (e.g., around the condensate storage tank, torus water storage tank, the demineralized water storage tank, and RCA yard). Additionally, OCNGS received approval to dispose of 17,000 cubic yards of dredged material from the Oyster Creek and Forked River containing licensed radioactive material to the east of the OCNGS.

Thirteen subsurface soil samples covering these areas were reported in the characterization data with several having residual radioactivity greater than the MDC.

Additionally, several sediment samples contained values greater than the MDC. The LTP should include a plan for subsurface soil sampling, sampling of subsurface soil below structure basement foundations, and volumetric sampling of sediment and surface water, including identifying which DCGL will be applied. (See also the discussion on the final status survey plan under Item 6 of Dose Modeling.)

10. Surveys shall be conducted to evaluate concentrations and quantities of residual radioactivity, and the potential radiological hazards of radiation levels and residual radioactivity detected (10 CFR 20.1501(a)). The MDCs for surveys should be capable of detecting residual radioactivity at or below the DCGL.

- 9, "Instrument Efficiency Determination for Use in Minimum Detectable Concentration Calculations in Support of Final Status Survey at OCNGS" described the derivation of instrument efficiency for 100 cm2 gas proportional/scintillation and 2" x 2" NaI (Tl) detectors. Table 3.1, "Nominal Instrument Efficiencies (ei)" listed Tc-99 and Am-241, with an active area of 15.2 cm2, as the calibration source for beta and alpha, respectively. Use of a source area less than the physical area of the detector results in an overestimate of the instrument efficiency (ei times the source-to-detector efficiency) and an underestimate of the gross activity. Explain how the efficiencies for large area sources (i.e., sources larger than the probe area) are determined.

Section 5.7.7.2, Structural Surface Beta-Gamma Scan MDCs and 5.7.7.5, Open Land Area Gamma Scan MDCs, used an index of sensitivity (d) of 1.38 for in Equations 5-11 and 5-14, respectively. This value assumed a 95 percent true positive detection probability of counts greater than the minimum detectable count rate (MDCR) and a 60% false positive. A signal at the 50% of DCGL is well outside of the background count distribution and would not require such a conservative d.

Ultimately the value should correspond to the count rate action levels to which survey personnel are instructed to respond. Alternatively, the use of such a conservative may only be necessary in Class 3 areas, where the licensee must ensure any site added ROCs are in fact at small fractions of the DCGL. Note that the confirmatory survey contractor utilizes a d value of 2.32, which corresponds to a probability of false positives of 0.25 and the acceptable probability of a detection at 95%. Evaluate the applicability of d value to the site-specific situation, justify the selection, and adjust the scan MDC as necessary.

The sources efficiencies in Enclosure 19, Table 4.2, Source Efficiencies as Listed in ISO 7503-1, did not reflect the International Organization for Standardization (ISO) 7503-1, Part 1, Evaluation of Surface Contamination or LTP, Table 5-11, Source Efficiencies as Listed in ISO 7503-1 values. Update Table 4.2 to be consistent with ISO 7503-1 and any impacted calculations.

Several of the static and scan MDCs in Table 5-8, Typical FSS Detection Sensitivities, are not reproducible using the equations provided in Section 5.7.7 and the data in Table 5-8. Clarify the source efficiency and source-to-detector efficiencies used for calculation of alpha and beta-gamma instrument MDCs.

Dose Modeling 1.

The OCNGS LTP and associated 100-year land use states that the site soils are not prime farmland or farmland of statewide importance, that there is a lack of agriculturally designated area within the vicinity of the site, and that using the site for commercial agriculture or to support raising livestock for meat and milk production is not considered plausible (LTP page 6-10). However, NRC staff review of soils data reveals that areas right outside of the site are important to local and state farmland (see figure below).

Clarify whether Holtec Decommissioning International, LLC (HDI) concluded that OCNGS site soils could be amenable to residential gardening or farming in the future, if the site is re-zoned and allowed to return to natural conditions. Plant and animal ingestion pathways could be important for the residential scenarios that HDI considers to be less likely but plausible (LLBP). This information will be important to assessing assumptions regarding plant and animal/product ingestion consumption rates/contaminated fractions in future analyses conducted by HDI for the LLBP exposure scenarios.

Figure 1, Soils Important to Farmland 2.

The OCNGS LTP and 100-year land use report, indicates that there is land available to support residential build out (LTP page 6-11) to meet the significant demand for residential development. It is unclear what land is available to support the population growth and demand for housing in the area. For example, page 40 of 48 of the Lacy Township Visioning Report (HGA 2007) indicates that much of the developable land within Lacy Township is built out and that redevelopment should be a priority.

3.

The OCNGS LTP provides information on domestic potable and non-potable wells within a 1-mile radius of the site (LTP page 1-5); however, it is unclear what these wells are used for (e.g., drinking water, irrigation, industrial use) and the applicability of the Lacey Township ordinance on municipal water supply in the surrounding area. It is also unclear how long and what portions of the OCNGS site are under groundwater exclusion zone restrictions in the Cape May and Cohansey Formations. Please clarify domestic groundwater well uses in the area surrounding the site; Lacey Township ordinance requirements related to municipal water supply for residences surrounding the site; any exceptions to the ordinance; and pertinent information on the enforceability of the requirements. Please clarify the area of restrictions on OCNGS groundwater use based on water quality (i.e., restrictions related to the groundwater exclusion zone) and the enforceability of those requirements. Please provide additional information on requirements related to closure/sealing of wells (see page 6-34 of the LTP); and any potential ongoing use of groundwater wells onsite for other than drinking water purposes, if allowable and applicable.

Figure 2, Groundwater Wells Near the OCNGS Site.

Image Credit: Figure 1-3 in OCNGS LTP.

Figure 3, showing groundwater exclusion zone at OCNGS.

Data accessed and image created from the following New Jersey website:

https://njems.nj.gov/DataMiner/Search/SearchByCategory?isExternal=y&getCategory=y&catNa me=Water+Supply+and+Geoscience 4.

The OCNGS LTP includes information on calculation of building surface DCGLs for above-ground buildings that are expected to remain following release of the site.

Buildings size is treated as a deterministic parameter at a value of 36 m2 in area and 3 m in height based on DandD defaults. Building and source size are considered physical parameters and building DCGLs should be developed based on site-specific information.

NUREG-6755, Technical Basis for Calculating Radiation Doses for the Building Occupancy Scenario Using the Probabilistic RESRAD-BUILD 3.0 Code, states "Several deterministic values used in the template file are site-specific, strongly affect the estimated dose, and should be modified to reflect actual site conditions when applied outside of this report. These parameters include time spent inside the building and room area and height (page 6-1). The impact of building size on DCGLs is unclear and could vary based on key radionuclides and associated dominant pathways (e.g., larger building sizes could lead to larger source areas leading to higher concentrations and dose in indoor air; however, higher concentrations and dose could be potentially offset by higher air exchange volumes with outdoor clean air leading to lower concentrations and dose from the inhalation pathway; smaller room sizes could lead to wall sources in closer proximity to receptors and higher doses from the external dose pathway).

5.

The HDI OGNGS LTP includes information on calculation of soil DCGLs. The source area was treated as a probabilistic parameter making it difficult to determine how the DCGL will be used to demonstrate compliance with release criteria. Additionally, it is unclear whether the contaminated zone and vadose zone thickness were assumed to be correlated in the probabilistic assessment (i.e., vadose zone thickness appears to be based on the actual vadose zone thickness observed at the site, which is inconsistent with the RESidual RADiation (RESRAD) conceptual model which assumes the vadose zone thickness is the thickness of the vadose zone located below the contaminated zone). Given the variability in contaminated zone and vadose zone thickness across the site, it is unclear that a single DCGL will be sufficient to demonstrate compliance with license termination rule criteria. FSS plans should address how FSS surveys will be implemented in various portions of the site where the thickness of the contaminated zone varies (e.g., what procedures are in place regarding the depth of measurements and averaging methods for samples to ensure that comparisons of FSS results to DCGLs will not lead to an underestimate of the dose).

Section G.7, Integration of Dose Modeling and Radiological Surveys of NUREG-1757, Volume 2, Rev. 2; and Section 3.5, DCGL Development of DUWP-ISG-02 provide guidance on integration of dose modeling with FSSs. Examples are provided on how dose from surface and subsurface residual radioactivity can be underestimated due to the averaging methods employed. Various issues can arise when comparing FSS survey results to DCGLs when lateral and vertical heterogeneity of residual radioactivity are present. The licensee should demonstrate a good understanding of the impact of area, thickness, and depth of residual radioactivity on dose to effectively apply soil DCGLs to the subsurface.

Use of a single surface and subsurface DCGL may be acceptable if survey result comparisons to DCGLs are consistent with dose modeling assumptions and do not lead to dilution of elevated concentrations that may be important to dose (e.g., use of composite soil samples that dilute elevated surface concentrations with relatively clean subsurface soil concentrations when surface soil concentrations dominate the dose from the external dose pathway). On the other hand, the use of a single DCGL could lead to unnecessary remediation if higher subsurface (or surface) DCGLs could have been developed but a single conservative DCGL was calculated.

6.

The OCNGS LTP includes probabilistic modeling to inform the selection of deterministic parameter values for use in deriving clean-up levels. As part of this process, the 25th or 75th percentile of the parameter distribution was used for risk-significant parameter depending on whether the parameter was positively or negatively correlated to dose.

NUREG/CR-7267, Default Parameter Values and Distribution in RESRAD-ONSITE V7.2, RESRAD-BUILD V3.5, and RESRAD-OFFSITE V4.0 Computer Codes was cited to provide support for the parameter distributions. NUREG/CR-7267 states the following with respect to distribution coefficients or Kds (see Table B-7, Base Values and Distribution Parameters for Crustacea Bioaccumulation Factors Used in RESRAD-ONSITE and RESRAD-OFFSITE Analysis (pCi/kg per pCi/L)):

Site-specific values should be used everywhere for each radionuclide. Default values and distributions are provided by the code for most radionuclides.

However, these values should be used with care because distribution can vary orders of magnitude.

The OCNGS LTP argues that the distribution coefficients vary orders of magnitude even for the same soil type illustrating the disadvantage of using a deterministic value for this parameter value. The large range of values is mainly because the parameter distributions represent many sites that may or may not include the characteristics of the site in question. Additionally, soil type is not always the key parameter affecting the distribution coefficient. While site-specific Kds may encompass a large range due to aleatory uncertainty or variability across the site given differences in geochemical conditions, the range of values in Kd is expected to be much narrower when site-specific information on geochemical conditions is considered.

The approach used by HDI is not entirely consistent with guidance provided in NUREG-1757, Volume 2, Revision 2, Appendix I, Technical Basis for Site-Specific Dose Modeling Evaluations, issued in July 2022, which indicates that for especially risk-significant parameters, that the 25th and 75th percentile of the parameter distributions may not be acceptable for use without additional support for the values selected. DUWP-ISG-02, Radiological Survey and Dose Modeling of the Subsurface to Support License Termination, (89 FR 79317, September 27, 2024) provides information on why use of the 25th or 75th percentile of the parameter distribution could lead to underestimates of dose particularly for parameter distributions based on sparse or low-quality data.

7.

HDI did not include the groundwater pathway in its industrial use scenario. Lack of consideration of the groundwater pathway was based on current restrictions on groundwater use in the Cape May and Cohansey Formations, and township ordinances requiring the use of the townships municipal water supply. However, in pre-LTP submittal meetings, NRC staff advised HDI to evaluate the viability of the groundwater pathway in sensitivity analyses at various points in time in the future as groundwater restrictions are indefinite and could be relaxed in the future. Furthermore, there is also uncertainty in the enforceability of local ordinances for long periods of time into the future especially given the apparent use of domestic water supply in the local vicinity of OCNGS. Please provide analysis showing the impact of the groundwater pathway on clean-up criteria or dose from residual radioactivity expected to remain at the site at the time of license termination. This analysis should also consider potential dose from existing groundwater contamination, should existing groundwater contamination contribute to dose at some point in time in the future when the groundwater pathway is assumed to be viable.

8.

HDI did not provide RESRAD-ONSITE input and output files in its technical basis documents supporting the OCNGS LTP. Inclusion of input and output files will be especially important for evaluating dose from the groundwater pathway and LLBP scenarios. For example, RESRAD-ONSITE output files provide information about dilution factors used in the simulations and will enable NRC to better evaluate DCGLs or dose estimates associated with the groundwater pathway.

9.

The calculation of DCGLs for building substructures considers an excavation scenario where building structures are excavated down to the depth of the water table. While it appears that sufficient material is brought to the surface to create an infinite source, it is unclear if the DCGLs will apply to building substructures below the water table. Please confirm that despite the assumption that substructures will only be excavated to the water table, that FSS will be conducted on basement substructures located below the water table for comparison against DCGLs associated with basement substructure excavation as well as in situ leaching. Alternatively, provide stronger technical basis for the assumption that portions of substructures located below the water table will not be excavated. Nonetheless, LLBP scenarios, including excavation of basement substructures located below the water table will need to be considered.

Provide additional information to support the use of the basement fill model-derived DCGLs for other types of tunnels and substructures that were not explicitly considered in DCGL development (LTP page 6-53).

10. Clarification of the approach that will be used to calculate dose from backfill materials is needed. Average concentrations from laboratory analysis of soil samples used for backfill are stated to be used to calculate dose from backfill. However, source geometry assumptions will need to be considered in assessing dose (i.e., the distribution of residual radioactivity such as depth and thickness will influence the dose from use of the soil as backfill). Additionally, use of a concentration of 0 pCi/g for samples below the MDC may not be acceptable. HDI should provide additional detail and justification for the approach used to estimate dose from use of slightly contaminated backfill soils.

Groundwater 1.

Staff cannot determine the adequacy of the groundwater monitoring network shown in Figures 2-16, OCNGS Cape May Aquifer Sample Points and Groundwater Elevations and Figure 2-17, OCNGS Cohansey Aquifer Sample Points and Groundwater Elevations, of the LTP for capturing potential groundwater contamination considering identified or possible contaminated sources areas. The pathway for groundwater migration of residual radioactivity from possible sources to locations of existing groundwater monitoring network based on Enclosure 21, 2022 Hydrogeologic Investigation Report, of the LTP which uses a larger number of well locations, has important differences with the implied pathways in Figures 2-16 and 2-17 of the LTP.

Staff notes that the groundwater flow directions are three-dimensional, and that the direction of the horizontal component spatially varies across the protected area of the site. The licensee should provide the justification for the adequacy of the groundwater monitoring network that considers possible subsurface contamination source areas identified in the 50.75(g) file and Section 10.2 of the Historical Site Assessment (Enclosure 3 to LTP submittal) that could potentially have led to contamination of groundwater. These possible source areas for groundwater contamination should align with the contaminated soils cited in Item 3 in the Site Characterization section above and Item 9 in Final Status Survey section.

2.

The compliance dose calculation includes the contribution from existing groundwater residual radioactivity. The licensee indicated that the residual radioactivity will be obtained from the current groundwater monitoring program. However, the licensee did not specify a plan that included (i) whether a maximum values from the monitoring wells will be used for the entire site or different values will be applied across, (ii) the period of time over which trends will be evaluated for determination of inputs for the existing groundwater contribution FSS compliance calculation and (iii) justification that residual radioactivity at monitoring well locations represent maximum concentrations in the groundwater across the site, or that uncertainty will be adequately incorporated in the residual radioactivity estimate.

3.

The licensee indicated in Sections 5.6, Groundwater, and 6.12, Groundwater Dose Contribution of the LTP that the groundwater sampling results less than the minimum detectable activity (MDA) will lead to a dose being set to zero. Staff considers MDA and minimum detectable concentration (MDC) to be synonymous for the purposes of groundwater analyses. Staff notes that Appendix G of the Annual Radioactive Environmental Operating Reports (AREOR) define the post priori MDC in a manner inconsistent with the MDC definition in MARLAP, Chapter 20, Detection and Quantification Capabilities, guidance (NUREG-1576). However, the MDA definition in Appendix G of the AREOR is consistent with the intent of the definition of critical level in MARLAP, which would appropriately warrant a determination of zero residual radioactivity. The loop would be closed if the licensee provided confirmation of the analytical laboratorys definition and calculation of post priori MDC values.

4.

Support for conceptual site model and hydrological input parameters for RESRAD are not currently reviewed due to the lack of a groundwater exposure pathway for the industrial scenario and lack of the LLBP analysis of the residential farmer scenario. (See Request for Supplemental Information (RSI)-9 of Enclosure 1, Oyster Creek Nuclear Generation Station (OCNGS) License Termination Plan (LTP) License Amendment Request Acceptance Review Request for Supplemental Information (RSI), on LLBP.)

When the LLBP residential farmer scenario analysis is provided, staff expects support will be provided for the flow and transport abstraction and for the input parameters in RESRAD.

Environmental 1.

In Section 8.5.1.2, Site Access, Land, and Water Use, of the environmental report identifies a public trail, Barnegat Branch Trail, that runs adjacent to the site along U.S.

Highway 9. Section 8.7.2, Offsite Radiation Exposure and Monitoring, does not discuss potential doses along this trail, nor is it discussed in NUREG-1437, "Generic Environmental Impact Statement for License Renewal of Nuclear Plants," (SEIS) for license renewal of the operating reactor in 2007. How far from the boundary of the site is this trail and is there any potential for dose to the public along this trail?

2.

In Section 8.5.2, Climate, there is no discussion of extremes for rainfall or temperature.

Please include the highest known rainfall in the area as well as the highest and lowest recorded temperatures. Please include the average rainfall at the site as well, with the wettest and driest months.

3.

In Section 8.5.3.2, Geology, please provide cross-section figures of the site geology, or provide in-text citations to another report that includes such figures. Discussion of the cross-section should include more details about the depth and thickness of the different geological formations, and hydrogeology of groundwater through these formations in Section 8.5.4.

4.

In Section 8.7.3, Environmental Effects of Accidents and Decommissioning Events, it states that the potential for decommissioning activities to result in offsite radiological releases (i.e., releases related to decontamination, dismantlement, and waste handling activities) will be minimized by use of procedures designed to minimize the likelihood and consequences of such releases. Please specify what procedures are used to minimize likelihood and consequences of offsite radiological releases.

5.

In Section 8.7.4 Storage and Disposal of Low-Level Radioactive Waste it states that the total estimated Low-Level Radioactive Waste (LLRW) volume for decommissioning is 1,403,164 ft3, less than 6% away from the high-end estimate of 1.5 million ft3 in the Decommissioning GEIS. Provide more details on what HDI is doing to ensure the total volume does not exceed the high-end estimate in the Final Generic Environmental Impact Statement on Decommissioning of Nuclear Facilities (NUREG-0586) (GEIS), and if the total actual LLRW does exceed the high-end estimate, what does HDI plan to do to ensure there are no environmental impacts from disposal of such waste? This section identifies 884 waste shipments have already occurred. What is the total volume of these shipments and is this consistent with the total estimated earlier?

6.

In Section 8.7.4, Storage and Disposal of Low-Level Radioactive Waste, Waste Control Specialist (WCS) facility in Andrews County, Texas is identified as the disposal site for the LLRW generated from decommissioning. Please provide information about the total estimated volume being shipped to WCS (e.g., is it the full 1.4 million ft3 estimated earlier, is waste being sent to more than one site, or is some stored-on site in NRC approved barrows?) and how much this is compared to the total open capacity at WCS to ensure there is sufficient space to receive all waste shipments from Oyster Creek.

7.

Section 8.8.3, Water Use, identifies a tritium leak from the turbine building in 2009.

Please provide more information about the leak, amount of tritium released, location of leak, impacts to groundwater and soil, and what remediation efforts were undertaken to correct the leak, or cite publicly available documentation with such information.

Additionally, please provide citations with data to support the statement, Radionuclides in groundwater range from non-detect to levels well below background and/or the NRC, Environmental Protection Agency (EPA), and state of New Jersey groundwater quality standards for radionuclides.

8.

In Section 8.8.4, Water Quality (Non-radiological), it states that sanitary waste generated at the site is discharged to the Lacey Township Municipal Utilities Authority.

Please provide an estimate of the total volume of waste generated and discharged.

9.

Section 8.8.6 and 8.8.7, Aquatic Ecology and Terrestrial Ecology, please define the action area for the proposed action, as defined in the Endangered Species Act and 50 CFR 402.02, Definitions.

10. Section 8.8.8.3, Northern Long-Eared Bat, identifies a sonic bat survey conducted in 2022 on the Finninger Farm property. Please provide a copy of this survey.

11. Section 8.8.17, Traffic Transportation, states that waste shipments are concluded to have no impact on the roads or traffic density. Please provide more information about the total traffic volume in the area and the estimated number of waste shipments from the site to support the claim that the site decommissioning does not meaningfully increase the average traffic of the area.

12. Section 8.9, Cumulative Impacts, states that the conclusion of cumulative impacts is based on the conclusion made in the SEIS in 2007. Are there any changes to the area around the site that could alter this conclusion since 2007? Are there any industrial sites or large construction projects near the site that could cumulatively impact ecology, groundwater, public health, etc.?