ML24030A747

Audit Report Attachment - Crystal River Unit 3 Nuclear Generating Plant LTP

ML24030A747
Person / Time
Site:	Crystal River
Issue date:	02/13/2024
From:	Jack Parrott Reactor Decommissioning Branch
To:	Reid B ADP CR3, Crystal River, FL
Shared Package
ML24030A740	List: ML24030A747 ML24030A748
References
EPID L-2022-LLA-0194
Download: ML24030A747 (1)

Text

CR3 LTP Audit Summary of Topics December 4-8, 2023

Compliance with Radiological Criteria for License Termination (CRCLT)

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 1a Clarify the approach to demonstrating compliance NRC and licensee staff discussed that the surface soil DCGLs and building with the 10 CFR 20.1402 dose limit for an structure DCGLs are each based on the entire 25 mrem/yr dose limit. NRC staff individual who is exposed to the following sources indicated to the licensee that those DCGLs do not account for dose contributions of radioactivity while residing onsite: from other contaminated media that a hypothetical receptor (e.g., resident farmer)

• Surface soil could be exposed to.

• Subsurface soil

• Pavement-covered areas and shallow NRC staff indicated that the licensee could reference NUREG-1757 Vol. 2, Rev. 2, concrete slabs Section 2.7 for guidance on how to account for multiple sources of contamination

• Buried piping during DCGL development.

• Buried structures This discussion topic resulted in the issuance of CRCLT RAI-1 Approach to Dose

• Groundwater Criterion Compliance Demonstration.

• Fill material.

FSS Explain the approach for incorporating the dose 12b contribution from the insignificant ROCs contributing less than 10% of the dose to their respective DCGL.

Page 1 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

2a Discuss the availability of the RESRAD-ONSITE During the audit the licensee uploaded RESRAD-ONSITE summary files for soil and RESRAD-BUILD model input and output files DCGL development to the portal. The NRC staff identified that the soil DCGL for the following analyses: values in the RESRAD summary files for some radionuclides do not match the

• DCGL calculations for each ROC DCGL values listed in Table 5.1 of the LTP resubmittal (e.g., RESRAD-Onsite

• Sensitivity analyses for each ROC Summary file CR3_DCGL_H3_

SUMMARY

.REP generated on February 13, 2022).

The licensee did not provide summary files for the sensitivity analysis for soil DCGLs. The NRC staff understands that the licensee intends to revise the soil DCGL dose model to include additional site-specific parameters, which could change the RESRAD-Onsite output files.

The licensee did not provide RESRAD-BUILD summary files from the development of or sensitivity analysis for building surface DCGLs. However, NRC staff learned that the licensee is considering developing other types of DCGLs (e.g., basement DCGLs, buried piping DCGLs). If the licensee develops a new dose modeling approach for structures to remain onsite at license termination, this request will pertain to the summary files for the new model(s).

This discussion topic, in part, resulted in the issuance of CRCLT RAI-2 DCGL Development and Justification for Building Surfaces Left at License Termination and CRCLT RAI-3 Technical Justification for Parameter Selection for Soil Dose Model.

Page 2 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

3a Clarify the plan to characterize the depth of soil NRC staff learned that the licensee intends to investigate the top 6 inches of soil contamination, including the criteria that will be for characterization purposes. If (1) the licensee finds no contamination on the used to determine when the characterization depth surface, and (2) if no subsurface source exists, the licensee will not further is adequate. characterize soil into the subsurface.

NRC staff understand that the licensee intends to provide their approach to surveying only the top 6 inches of soil unless certain criteria are met (e.g., a potential subsurface source exists). This can be accomplished in a revision to Chapter 5 of the LTP to explain the approach and discuss the specific criteria for determining subsurface samples are needed. This discussion topic, in part, resulted in the issuance of SC RAI-1 Site Characterization.

Additionally, NRC staff understands that the licensee intends to update the description of the QA/QC program in the LTP to indicate whether they will perform a limited number of subsurface samples in some areas, even if criteria for completing subsurface characterization are not met. The NRC staff also understands that the licensee intends to replace wording in LTP Section 5.4.3.2 regarding sampling up to a depth of 1 meter with criteria for determining the appropriate depth of soil characterization.

3b Clarify the basis for the contamination depth in The NRC staff clarified that the "contaminated zone thickness" parameter in models used to calculate soil DCGL values, RESRAD-ONSITE should be based on the depth of soil contamination at the site.

including supporting sensitivity analyses.

This discussion topic, in part, resulted in the issuance of CRCLT RAI-2 DCGL Development and Justification for Building Surfaces Left at License Termination and CRCLT RAI-3 Technical Justification for Parameter Selection for Soil Dose Model.

Page 3 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

4a Clarify the process for selecting the following in The NRC staff learned that the licensee did not have access to additional sensitivity analyses for each dose model: information about the selection of parameters to represent with stochastic

• Physical parameters to represent with distributions, which parameters to correlate, and the values of correlation stochastic distributions. coefficients used in the sensitivity analyses for soil and building DCGLs.

• Parameter distributions to correlate.

• Values of correlation coefficients The NRC staff indicated that the NRC staff could evaluate (1) whether the information in Enclosure 8 of the LTP was sufficient to reproduce the licensees sensitivity analyses; (2) whether representing additional parameters stochastically changed the sensitivity analysis results; and (3) whether changing the values of correlation coefficients or correlating additional parameters changed the sensitivity analysis results. Because the licensee described plans to change the RESRAD-Offsite model later in the audit, these NRC actions cannot take place until the NRC staff receives the new model input from the licensee.

5a Clarify the following information related to sorption NRC staff learned that the licensee does not currently have additional bases for of radionuclides to site soil: the modeled soil sorption coefficients beyond the information presented in the LTP

• whether berm soil can be represented by a (i.e., generic values were used because of the variety of soil types onsite (sandy more specific soil type than the generic soil soil, limestone, fill material)).

type

• whether surface areas described as sandy The NRC staff understands that the licensee intends to provide an explanation of soil underlain by limestone can be whether using sorption coefficients for generic soil is representative or delineated conservative based on the soil types expected to be onsite at license termination.

• whether additional information is available This could be accomplished in Enclosure 10 of the LTP.

to support the determination that the generic soil type represents site conditions."

6a Expand upon the technical justification (i.e., During audit discussions, the NRC staff and the licensee concurred that the supporting analysis) for the selection of the building building occupancy scenario is not a realistic exposure scenario for basement occupancy scenario as the most structures and buried piping, since no buildings will remain at grade upon license conservative/bounding scenario for backfilled termination. The licensee discussed that a person would not physically be in the basement substructures and embedded piping, as building substructure since the basement will be backfilled. However, the licensee stated in the LTP. indicated that it may develop a new dose modeling approach for basement structures and buried piping.

This discussion topic, in part, resulted in the issuance of CRCLT RAI-2 DCGL Development and Justification for Building Surfaces Left at License Termination.

Page 4 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

7a Clarify which DCGLs the licensee will use in the NRC staff explained that the term Operational DCGL is highly defined by the field for FSS? In other words, what are the licensee in the LTP and has varied from site to site in the past. Some licensees Operational DCGLs? Will the LTP resubmittal have developed Operational DCGLs based on an a priori fraction of the 25 include these Operational DCGLs and technical mrem/yr dose limit from each source term when multiple contaminated media are justification? present. Others have used Operational DCGLs to add a safety margin from the 25 mrem/yr dose limit.

The licensee explained their definition that Operational DCGLs are those that are compared to scanning results after accounting for all ROCs and all pathways.

NRC staff learned that the licensee is planning to develop one set of DCGLs for soil and possibly apply modifiers to that set of DCGLs for other contaminated media (e.g., basement structures, buried piping). The licensee does not intend to create an additional set of Operational DCGLs. NRC staff understand that the licensee will provide the approach for developing soil DCGLs, DCGL values for each radionuclide of interest, a new list of radionuclides of concern, possible modifier values for other contaminated media, sensitivity analysis, and the approach to account for insignificant contributors.

Depending on the licensees development of and justification for the soil DCGLs, this discussion topic may be related to the questions asked in CRCLT RAI-1 Approach to Dose Criterion Compliance Demonstration.

Page 5 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023 Hydrology and Groundwater (HGW)

No. Discussion Topic NRC Staff Observations & Proposed Closure Path Dose due to existing groundwater contamination Staff understands that the licensee will take the approach of demonstrating that all (19) radionuclides, except tritium, in the site-1a A discussion is needed on the completeness of specific suite of radionuclides will be below the critical limit (detection DQOs for groundwater monitoring and inputs decision) in the uppermost saturated zone at the site. For tritium, staff needed for FSS dose calculations. DQOs should understands that the licensee intends to develop support for address all the site-specific ROCs listed in LTP designating tritium levels as background.

Table 5-1, a sampling plan as appropriate for those radionuclides, the approach for estimating the Licensee described the meaning of U (undetected), LLD, and variety maximum concentration in the groundwater, period of other terms in the LTP, annual monitoring reports, and laboratory of time over which trends in data will be evaluated, reports. Licensee provided several laboratory procedures and the method for accounting for the distance from documenting the methodology for laboratory measurements. Staff likely sources to concentrations in monitoring wells. pointed to guidance on reporting sample results in NUREG-1576 In addition, the discussion should include a (MARLAP). Staff understands that the licensee intends to confirm if description of the calculation to determine the dose their reporting of results is consistent with MARLAP for the detection from groundwater contamination, if any, that exists at decision and quantification of low levels of radionuclide.

the time of license termination.

In parallel with the above discussions for both items in this group, 2a Clarify the meaning of measurement results of staff understands that the licensee intends to pursue an alternative radionuclides in groundwater reported as U or LLD in approach for dose due to existing groundwater contamination. Staff the LTP and AREORs and described in the ODCM. understands that the licensee intends to assess the possibility of Discuss how the reported laboratory results are demonstrating that the saturated groundwater at the site is impacted consistent with the MARLAP guidance in NUREG-by saltwater intrusion, and thus, would not meet the definition of an 1576, Chapter 20, or provide justification for not aquifer by the state of Florida. If staff finds the demonstration following the guidance. adequate, then staff will not review the dose due to existing groundwater contamination nor the reporting details for low levels of radionuclides in groundwater. The licensee and staff discussed that groundwater contamination should still be characterized even if the saturated groundwater does not meet the definition of an aquifer.

Page 6 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 3a Discuss the relationship between the datums used in The licensee confirmed the relationship between the three vertical the set of LTP submittal documents. The discussion datums used at the site for different technical areas. Staff would be facilitated by one or two cross-sections that understands that the licensee intends to primarily utilize the plant illustrate the relationships of features and datum, and intends to clarify the relationship when other datums are components between the survey units on the berm used (such as local building coordinates, subsurface sampling of the power block and survey units outside the area elevations, or groundwater conditions). To support the conceptual of the berm. These cross-sections should include site model, staff understands that the licensee intends to develop a ground surface, basements of subsurface structures cross-section that integrates the features listed in the discussion that will remain, geological or hydrogeological layers, topic.

and typical or average groundwater table elevations.

Discuss the datum that is planned for all elevation-related FSS information (e.g., subsurface sampling, excavations).

Page 7 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path Inputs for groundwater pathway in dose models The licensee explained that parameter values reflected properties or conditions of both berm and non-berm areas; i.e., a composite 4a Clarify how the hydrogeological parameters in the representation. The licensee further explained their conceptual model berm area relate to the conditions outside the berm for the berm area and how it differed from that of the general site of the CR3 plant area, and vice versa, or that dose is conceptual model. Staff understands that the licensee intends to not underestimated for survey units in either area. evaluate parameter values that might not apply both to the berm and off-berm areas (e.g., UZ thickness, hydraulic conductivity, gradient) 5a Discuss the reasonableness of the CZ and UZ and determine if they are non-conservative as applied to either berm parameters of precipitation and hydraulic or non-berm areas.

conductivity in the soil dose model for representing site conditions, including the coherency of the The licensee clarified that the berm was constructed of crushed hydraulic conductivity with the coefficients for limestone, which is significantly different than the unsaturated zone evapotranspiration and runoff. Also, discuss why the media in areas surrounding the berm. The licensee also described upper end of the precipitation as used in the soil the configuration of the curtain wall below the main structures; the dose model in terms of its contribution to dilution at curtain wall fully was enclosed on the sides and the bottom. The the wellbore in RESRAD. licensee mentioned that some small amount of designed leakage occurred. Considering the crushed limestone and curtain wall, the 6a Clarify the supporting bases for several hydrological licensee described a separate conceptual model for flow and soil dose model inputs. transport in the berm area and the basis for the choices of inputs for unsaturated zone (vertical) hydraulic conductivity and precipitation.

7a Discuss the analysis that produced the large value of Staff understands that the licensee will consider the justifications for hydraulic conductivity that is being applied to the soil RESRAD input parameter values in light of the RESRAD abstracted dose model. Discuss how the selected inputs for model and the porous media of the berm.

hydraulic gradient are consistent with groundwater conditions at the site, particularly for survey unit Licensee provided H&A TSD #134300 on the portal, which was cited areas. in the LTP as documenting the supporting bases for selected RESRAD-ONSITE input parameters. The document contains some 8a Clarify the support for hydrogeological parameters additional information for several parameters, however, the gradient leading to significant wellbore dilution for the soil information was TBD. Staff understands that the licensee intends to dose model. update the basis for the selected gradient value, including justification for why the gradient is appropriate for all areas of the site under all tidal conditions.

[7a] Licensee explained that the choice to use default gradient was driven by wide range of gradients found across the site, and that the Page 8 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path gradients change dependent on tidal conditions. Staff understands that the licensee intends to evaluate appropriateness of the large flux value produced by large hydraulic conductivity and moderate gradient for the saturated zone at the site. Staff understands that the licensee intends to reassess sensitivity results if parameter values change significantly.

[8a] The licensee and staff discussed the parameters that affect the calculation of wellbore dilution in RESRAD-ONSITE. Staff provided a link to additional descriptions of the dilution calculation contained in an Interim Staff Guidance (ML23177A612). Staff understands that the licensee intends to evaluate and justify the parameters that affect borehole dilution for CR3 in RESRAD-ONSITE.

[All] In parallel with the above discussion for all the items in this group, staff understands that the licensee intends to pursue an alternative approach for the groundwater pathway in CR3 dose models. Staff understands that the licensee intends to assess the possibility of eliminating the groundwater pathway by demonstrating that the saturated groundwater at the site is impacted by saltwater intrusion, and thus, would not meet the definition of an aquifer by the state of Florida. If staff finds the demonstration adequate, then staff will not review the values or bases for hydrological input parameters used for the groundway pathway in RESRAD-ONSITE.

Page 9 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023 Site Characterization (SC)

No. Discussion Topic NRC Staff Observations & Proposed Closure Path For survey unit classification: NRC staff and the licensee discussed the classification and reclassification of survey units, including those previously remediated.

1a Discussion of classification of downgrading and NRC staff learned reclassification of survey units will not occur without previous remediated survey units. NRC approval prior to implementation. However, the licensee explained they do not consider classification of soil beneath a demolished building 1b Discuss the methodology that would be used to to not constitute "reclassification." As an example, NRC staff and the inform the basis to downgrade survey unit licensee discussed survey unit EOCZ-04, which was remediated during classification. the operational phase of the site. In addition, the licensee discussed WOCZ-03 as an example of downgrading a survey unit classification.

The licensee discussed the history of the RMSW-D Tank, including the contamination incident, to include remediation activities.

This discussion topic resulted in the issuance of RAI SC-1, Site Characterization.

Page 10 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 2a Describe surveys conducted and their results, or NRC staff and the licensee discussed the importance of plans for the characterization building interiors, characterization data in determining radionuclide mixtures, insignificant building basement structures, embedded piping, contributor (IC), and input to dose modeling. The NRC staff learned the backfill material, and subsurface soils. licensee completed additional sampling in outdoor areas and buildings.

Limited subsurface samples were collected from the BERM area with no embedded piping characterization completed to date. Additional survey and sampling planned includes core sampling in the Reactor Building, embedded piping sampling, and supplemental survey and sampling of previously surveyed outdoor areas. The NRC staff understands, for existing characterization data, the licensee anticipates providing supplemental information to Chapter 2 of the LTP by the first quarter of 2024. The NRC staff clarified if only Class 1 areas remain to be characterized, receiving supplemental data will not hold up the approval of the LTP.

The discussion topics above resulted in the issuance of RAI SC-1 Site Characterization. The NRC staff was tasked with evaluating the additional characterization data needed to support the LTP review and approval. The NRC staff communicated this information in RAI SC-1, Site Characterization.

Page 11 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path Concerning characterization survey methodology: NRC staff and the license discussed the methodology used for conducting characterization surveys including random or systematic 2b Explain the process for conducting site sampling, judgmental sampling, determination of sample locations and characterization measurement and sampling and numbers, scanning surveys, and instrument sensitivities. The licensee sufficiency of these results for determining input to informed NRC staff characterization surveys were not performed to the the FSS design and radionuclide mixture/fractions. rigor of an FSS, and at present, data will not be included in the FSS analysis. NRC staff emphasized the importance of the characterization 2c Discuss the results of gamma scan surveys for classification of areas, including soils under buildings and providing conducted on impacted open land areas and how justification for these decisions.

the results of these scans were used to identify areas of biased sampling. The NRC staff learned there were no gamma scan surveys during site characterization surveys of impacted open land survey areas. For the purposes of identifying judgmental sampling locations, the licensee focused on low-lying areas, ditches, areas of concern identified in the historical site assessment, and professional judgment. The NRC staff learned gamma scan surveys were conducted during surveys of non-impacted areas and some previously surveyed open land areas (e.g.,

CHAR-09, WOCZ-03).

This discussion topics resulted in the issuance of RAI SC-1 Site Characterization. Upon receipt of outdoor area gamma scanning surveys, NRC staff will review the information and provide the licensee with any questions concerning these surveys.

2d For land areas, there were only twelve out of 123 The licensee clarified the results for 117 samples (4 duplicates) are characterization samples sent for HTD analyses available in Enclosure 20, Table 3-3, including analysis for the full suite with the samples were selected of radionuclides.

randomly. Explain how analyzing <10% of the total land area samples for HTD radionuclides is There is no further action for NRC staff or the licensee at this time.

adequate to assess HTD contributions for land areas. Explain why the samples were analyzed for only a subset of the HTD radionuclides contained in Table 2.4, CR3 Site-Specific Suite of Radionuclides of Concern.

Page 12 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 2e Describe how the results of ongoing NRC staff understand the licensee intends to provide supplements to characterization efforts will be communicated to existing characterization data in the LTP as they become available.

NRC staff.

Page 13 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023 Plan for Radiological Site Remediation (PRSR)

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 1a Describe the justification for applying 2014 rather The licensee provided a revised ALARA evaluation for NRC staff than inflated values for the averted dose and evaluation for soil excavation and scabbling in "Crystal River Unit 3 value of statistical life, including the use of Nuclear Generating Plant ALARA Evaluation, Rev 1, Draft," which sensitivity analysis evaluating low, best, and high included several updated inputs to the present worth of the future estimates. collective averted dose (PW(ADCollective)) calculation. These revisions included the necessary information for the staff to continue their review; 1b Explain the rationale for using of a 7% discount however, the consideration of a zero-discount rate was not included.

rate parameter as a conservative approach when calculating the ALARA limits. NRC staff understand that the licensee intends to revise the draft ALARA evaluation to include:

1c Discuss the approach for selecting 1 m2 as the survey unit area and 1 m3 as the waste volume in

• An analysis for a zero-discount rate and select the discount rate the generic cost/benefit analysis. used in the ALARA with justification for the value selected.

• A revision of the text and inclusion of a step for determining the 1d Explain the rationale for using only Cs-137 and ratio of the cost of remedial actions to the value of the averted Co-60 verses all the radionuclides of concern in dose.

the generic ALARA evaluation.

Additionally, the NRC understands the licensee intends to finalize the draft ALARA evaluation report, update the discussion in Chapter 4 of the LTP, and replace or supplement the attachment to Chapter 4.

Page 14 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 1e Clarify why the LTP provides only a generic NRC staff learned the licensee no longer plans to conduct survey unit ALARA analysis for building surfaces. Clarify specific ALARA evaluations instead focusing on a generic ALARA what remediation activities are considered as a analysis. A soil excavation and scabbling scenario were considered for part of this analysis and why other remediation the generic evaluation with the licensee inquiring about other generic activities dont require an ALARA evaluation. scenarios that should be considered.

When are survey unit specific ALARA evaluations conducted and how they are NRC staff evaluated the generic scenarios and recommended the documented? Describe any alternative disposal licensee benchmark their generic ALARA scenarios against other paths under 10 CFR 20.2002 being utilized for license termination plans to determine if similar scenarios are soils. applicable to the Crystal River site.

Additionally, NRC staff learned the licensee will not use alternative disposal paths under 10 CFR 20.2002 with all their waste shipped to the Waste Control Specialists.

1f Clarify the meaning of remediation of soils NRC staff explained in Section 4.4, ALARA Analysis, and the Crystal beyond the DCGLs. Does the licensee mean River Nuclear Generating Plant Generic ALARA Evaluation, the text remediation below the DCGLs is not likely to be uses the phrase beyond the DCGLs. The licensee clarified they meant cost effective in the LTP Section 4.4, ALARA below the DCGLs.

Analysis, and the Crystal River Nuclear Generating Plant Generic ALARA Evaluation. NRC staff understand the licensee intends to update the text in the LTP to read below the DCGLs.

Page 15 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023 Final Radiation Survey Plan (FSS)

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 1a For alpha/beta instruments, Table 5.8 presents an NRC staff emphasized a priori static and scan minimum detectable efficiency. Clarify of the type of efficiency included in concentrations (MDCs) should be directly comparable to the surface Table 5.8 (e.g., instrument efficiency or total and soil DCGLs. NRC staff requested all inputs for the static and efficiency.) scan MDC equations to facilitate validation of the licensee calculations. NRC staff learned the licensee no longer intends on 1b Explain how the instrument efficiency (ei) will be applying a source-to-detector distance efficiency to / efficiencies adjusted for in conditions where the source term in since measurements will be taken at contact or near-contact with the field is larger area than the calibration source the surface. Additionally, the licensee will calculate and apply used for determining the source-to-detectors weighted instrument efficiencies based on site wide, building distance in Table 5.9. specific, or survey unit specific radionuclide mixtures. The NRC staff and licensee discussed the appropriateness of the index of 1c What radionuclide mixture is assumed for sensitivity (d) to the site and alternatives to the current value.

determination of the weighted instrument efficiency (ei)? Explain how the instrument efficiency will be This discussion topic resulted in the issuance of RAI FSS-3, adjusted for HTD radionuclides or variable mixtures Instrument and Laboratory Analysis Minimum Detectable for the ROCs included in Table 2.4, CR3 Site-Concentration.

Specific Suite of Radionuclides of Concern.

1d What radionuclide mixture is assumed for determination of the weighted source efficiency (es)?

Explain how the source efficiency will be adjusted for HTD radionuclides or variable mixtures for the ROCs included in Table 2.4, CR3 Site-Specific Suite of Radionuclides of Concern.

1e Explain the selection of 1.38 as a sensitivity index (d)

Page 16 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 2a Identify what advanced technologies are under NRC staff learned that the licensee will not use advanced consideration, their proposed use, and the criteria for technologies or ISOCS. NRC staff clarified for the licensee that providing a technical basis document for review. advanced technologies are those technologies not routinely used by the industry for area surveys; however, there is a process for 2b Clarify the proposed uses of ISOCS and the criteria notifying the NRC when new technologies are considered.

for providing a technical basis document for review.

Include this discussion of instrument sensitivity and NRC staff understands that the licensee intends to update the LTP calibration. to remove references to ISOCS and advanced technologies.

2c Explain how the HTD radionuclides will be accounted for in the in situ and advanced technology measurements.

2d Discuss the NaI detector or ISOCS methodology for identifying the potential presence of subsurface contamination (i.e., greater than 15 cm in depth) and the triggers for further investigation. How will this methodology be used with excavations (e.g., with or without overlying soil)?

2e Discuss the methodology for use of ISOCS for scanning.

Page 17 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 3a For onsite gamma spectroscopy, for all NRC staff emphasized the need for a priori onsite and offsite measurement media and geometries discuss how analytical laboratory MDCs directly comparable to the DCGLs. For the MDCs will meet the applicable DCGLs. onsite analyses, this information could be included in existing instrument sensitivity tables. For offsite sample analysis, the NRC 3b For onsite alpha and beta analyses, for all staff recommends the licensee include in the LTP the MDCs by measurement media and geometries discuss how analysis type, technique, method, and media used. NRC staff the MDCs will meet the applicable DCGLs. learned the onsite laboratory is required to meet 10-50% of the DCGL and the offsite laboratory to meet 10-50% of the DCGL for 3c For the vendor laboratory, describe the analysis easy to detect radionuclides and 1-5% of the DCGL for HTDs.

type, technique, method, and MDCs by media.

This discussion topic resulted in the issuance of RAI FSS-3, Instrument and Laboratory Analysis Minimum Detectable Concentration.

Page 18 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 5a How are scanning ILs calculated such that a gross NRC staff and the licensee discussed investigation levels (ILs) and count rate observed during scanning is equated to how they are applied in the field. NRC staff learned the licensee will the DCGL values designated for Class 1 and Class 2 include values comparable to field instrument readings in a revision survey units? of Table 5.4, Investigation Levels. The NRC staff clarified that the use of 3-sigma above the mean or detectable above background, 5b Explain the basis for the 3-sigma above the mean as if used as scan or static ILs, will require an explanation of the an investigation level for Class 1 direct derivation. NRC staff also recommended the license consider measurements. How is this statistical parameter specifying the appropriate DCGL (DCGLW or DCGLEMC) for ILs in determined for use as an IL and how have these Table 5.4.

values have been verified to be less than the DCGLEMC? NRC staff understand the licensee intends to update Table 5.4, Investigation Levels in the LTP to reflect ILs implemented during 5c How is detectable over background established for FSS and will evaluate updating DCGL to include the appropriate Class 3? subscript. NRC staff understand the licensee intends to provide justification and explanation of the derivation of ILs applying 5d Clarify in Table 5.4, Investigation Levels, Table 5.7, statistical parameters or detectable above background.

Investigative Actions for Individual Survey Units, Section 5.3.6.4, Remediation and Reclassification, Section 5.4.5.1, and other areas of the LTP discussing investigation levels whether DCGL refers to DCGLw.

Page 19 of 36 Attachment CR3 LTP onsite Audit Summary of Topics December 4 - 8, 2023

No. Discussion Topic NRC Staff Observations & Proposed Closure Path 6a-i Describe how are the actual minimum detectable NRC staff provided an overview of the expectations concerning concentration for scanning surveys where HTD measurement and sampling of HTD radionuclides, and their radionuclides are present will be calculated. consideration in MDC calculations. The current LTP indicated that the licensee does not plan to use surrogate ratios. NRC staff ii Describe how HTD ROCs will be accounted for learned the licensee is evaluating the use of Cs-137 or all gamma during scanning and direct measurements in the emitters as surrogates for HTD radionuclides. NRC staff absence of the use of surrogate radionuclides. emphasized if the licensee plans to forego the use of surrogates 100% of the FSS samples would require analysis for all ROCs.

iii Describe the sampling protocol for measurement of HTD radionuclides, including the selection of random This discussion topic resulted in the issuance of RAI FSS-2, or systematic and biased samples for HTD analysis Surrogate Radionuclides.

and the collection of sufficient samples to demonstrate a statistically significance.

iv Explain how the instrument efficiency is determined for mixtures containing HTD radionuclides.

v Discuss the ROC mixtures identified in various media.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 6b-For gross activity DCGL and measurements: NRC staff and the licensee discussed the derivation of gross activity DCGLs (DCGLGA) and their application. The NRC staff requested i The LTP did not specify whether both alpha and clarification on measurement types used to determine residual beta measurements will be made on structure radioactivity on structures (e.g., alpha, beta, alpha/beta). The NRC surfaces during characterization or for the FSS. staff learned the licensee is currently evaluating their survey What are the requirements for alpha scans? If only techniques and gross activity DCGLs. Updates to the DCGLGA will beta measurements will be performed, describe how include the consideration of recent radionuclide mixtures, including the release criteria for alpha emitting ROCs will be HTDs. The licensee currently plans to use independent alpha and demonstrated. beta measurements using weighted efficiencies and separate gross alpha and beta DCGLs. The NRC staff asked for clarification on ii Clarify whether both alpha-plus-beta measurements DCGLGA reevaluation in the event of a new radionuclide or independent gross alpha and gross beta distributions.

measurements are used to develop the gross activity DCGLs, and the method for calculation of the NRC staff understands the licensee intends to update the LTP to:

DCGLs. For example, will a gross activity DCGL be developed based on fractional amounts of ROCs

• Clarify the survey types used for buildings structures (e.g.,

and alpha-plus-beta measurements, or will alpha/beta scans and direct measurements) and the independent gross beta and gross alpha DCGLs be instrument mode (alpha only, beta only, or alpha plus beta) developed based on fractional activity and then the used to determine alpha and beta activities.

unity rule be applied to the alpha and beta measurements?

• Describe how gross activity DCGLs will be calculated and how gross alpha and beta instrument readings will be iii Explain how the HTDs will be accounted for in a correlated to these DCGLs.

gross activity DCGL in lieu of the surrogate method for surface activity measurement data assessments.

• Remove or supplement the discussion concerning How will the contributions from HTDs be accounted reevaluation of the DCGLGA with new radionuclide for in application of the unity rule, particularly since distribution data.

limited data is available on HTD contributions to the total source term?

If the new radionuclide distribution data found to be more appropriate for use results in an increased DCGLGA, describe the process that will be followed.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 7a-i Describe when turnover surveys are used and the The NRC staff learned turnover surveys are conducted post-intended use of these data. How do turnover surveys remediation to determine when a survey unit is ready for FSS for differ from remediation surveys? Class 1 and Class 2 areas. Turnover surveys statistics may be used to provide input data to the FSS design.

There is no further action for NRC staff or the licensee at this time.

7a-ii Explain what is meant by equivalent evaluation in NRC staff learned the licensee will not use equivalent evaluations.

Sections 5.1.3.2, Survey Preparation and the methodology for conducting these evaluations. NRC staff understand the licensee intends to remove references to equivalent evaluations from the LTP.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 7a-iii Discuss the survey methodology used to support the During the site tour, NRC staff learned Crystal River used dust contamination control program, including verification suppression, containment structures with negative ventilation, and of isolation and controls and evaluation of haul structure decontamination to free release levels, where possible, to paths. control the spread of contamination to the environment from decommissioning activities. Additionally, the licensee has a routine follow-up surveillance program conducted for previously released areas.

NRC staff and the licensee discussed maintaining isolation and controls in areas with active non-nuclear operations at the Crystal River Energy Complex (CREC). NRC staff learned traditional isolation of areas (e.g., fences, ropes) following FSS may not be possible. The licensee explained there is a process in place to disseminate information on postings and other controls to CREC personnel. The licensee informed NRC staff portions of the isolation and control program may be discontinued on a risk-informed basis following confirmatory surveys.

NRC staff understand the licensee intends to supplement Section 5.2.4.4, Isolation and Control Measures to expand on the contamination control measures implemented at the site.

Additionally, NRC staff understand the licensee intends to provide isolation and control procedures and an explanation of the dissemination of isolation and control protocols to the CREC for NRC staff review.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 7b-For discrete radioactive particles (DRPs): The NRC learned the licensee benchmarked their radiological control program with other sites, such as Zion, who had experience i Describe the criteria where adjustments to DQOs with DRPs. As a result, Crystal River has improved the process for and survey plans will be made for discovery of hot managing hot particles and DRPs in all Radiological Control Areas particles and/or DRPs. How will these incidents be by focusing on controlling the generation at the source (e.g.,

documented, including the material origin, cause(s) containment structures, fixative, encapsulation, capping, for the materials presence, and the extent of the vacuuming). In addition, the licensee conducts routine surveys for condition? hot particles and DRPs. When hot particles or DRPs are found, an investigation is conducted and documented in the corrective action ii Explain how the survey and sampling methodology program.

will be modified in the event DRPs are found, including how the physical and radiological NRC staff understand the licensee intends to supplement the characteristics of the DRPs will be determined. For information in Chapter 2 of the LTP taking credit for operational which survey units will revise survey methodologies practices and surveys conducted to control the generation of DRPs.

be implemented when DRPs are identified.

During the audit NRC staff informed the licensee of an information notice in draft, which contains insight on how to address DRPs. The NRC staff communicated the need for additional explanation on how DRPs will be addressed during the FSS process and how DRPs events will be documented. The discussion should include the cause and extent of the condition (physical and radiological characteristics of the DRPs). Clarity related to the conditions for adjustments to the Data Quality Objectives (DQOs) and survey plans and the survey methodology employed following DRP discovery (e.g., radionuclide identification, scan survey approach and coverage, consideration for adjacent survey units, remediation) would help inform the staffs review.

NRC staff understand that the licensee intends to include in the LTP a discussion of DRP survey and sampling protocol, and the criteria for adjusting their DQOs and survey plans when DRPs are identified.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 7b-iii Describe the method proposed to evaluate dose NRC staff and the licensee discussed the potential need for from DRPs additional information on the method for assessing potential dose from DRPs should they be found during FSS or confirmatory surveys.

8a-i For basement structures, what are the types of NRC staff understand that the licensee intends to revise the LTP surface activity measurements to be conducted and/or Technical Basis Documents (TBDs) to include information on (e.g., alpha, beta, a combination)? Explain how the their approach to surveying below grade structures. This approach surface activity release criteria will be expressed for will include information about their surveying techniques for below comparison to a gross activity DCGL. grade structures prior to backfill, the types of measurements (alpha, beta, gamma) as well as a narrative of how the surface activity will be compared to gross activity DCGLs. The gross activity DCGLs will be developed either from the current building surface DCGLs OR new substructure DCGLs that the licensee may develop.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 8a-ii Discuss the technical justification to support the NRC staff learned that the licensee referenced a 10 mm depth from basis for selecting a volumetric concrete sample of guidance in NUREG 1757 Appendix H Criteria for Conducting 10 mm in thickness after removal of the surface Screening Dose Modeling Evaluations, which applies to layer for subsurface structures. determining when screening criteria are appropriate. The licensee has been implementing a practice during characterization surveys to scabble the uneven paint and epoxy from surfaces (e.g., basement floors) of approximately 10 mm. NRC staff understand that the 10 mm thickness does not apply to volumetric sampling but rather the thickness of material that will have been removed from the surface at the time of FSS. The licensee stated that its current practice is to continue with volumetric sampling (core boring) if and when contamination is found on the surface.

NRC staff understand that the licensee intends to:

• Evaluate verbiage in Chapter 5 of the LTP related to 10 mm thickness and scabbling and determine if that language needs to be included for FSS,

• Include more detailed information about its proposed use of core boring to assess volumetric contamination, including the sample approach, laboratory procedures to analyze the cores (e.g., cutting into discs at certain depths), etc., and

• Evaluate the language in Chapter 2 of the LTP related to core boring for the purposes of site characterization to inform new language in Chapter 5.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 8a-iii Section 5.4.3.2, Volumetric Concrete NRC staff learned that the licensee's initial position of the Measurements states Volumetric sampling of efficiencies being too high would be a result of the uneven contaminated concrete, as opposed to direct paint/epoxy on building surfaces. However, since the paint will measurements, may be necessary if the efficiency or already have been removed from the building surface at the time of uncertainty of the gross beta measurements is too FSS, the licensee does not plan to employ this approach.

high. Explain how the efficiency being too high is an issue.

NRC staff understand that the licensee intends to determine if the verbiage related to the efficiency of gross beta measurements being too high in Section 5.4.2.4 will be removed from the LTP.

8a-iv Discuss the technical justification (including pathway NRC staff learned that the licensee is considering developing other analysis) for using building surface DCGLs as a types of surface DCGLs (subsurface structures as opposed to conservative approach for subsurface applications building surface). NRC staff and the licensee discussed different (i.e., basement structures, piping). exposure scenarios related to building surface vs. subsurface structure dose modeling. NRC staff cited NUREG 1757 Appendix J for examples of exposure scenarios and applicability of RESRAD to subsurface modeling.

This discussion topic, in part, resulted in the issuance of CRCLT RAI-2 DCGL Development and Justification for Building Surfaces Left at License Termination.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 8a-v For concrete measurements, explain the criteria for NRC learned that in areas of activation potential (i.e., in the determining at what point (depth) contamination can bioshield), the licensee plans to perform volumetric sampling in the no longer be adequately assessed by surface form of core boring. The licensee noted that surface measurement activity measurements and should be replaced by can only detect contamination to a depth of about 10 mm. The volumetric measurements, particularly in areas licensee noted that when performing volumetric sampling, the subject to neutron activation. How will compliance licensee would typically take core bores to 1 m.

with release criteria be demonstrated in the event volumetric concrete samples replace surface activity measurements? Describe what volumetric sampling NRC staff understand that the licensee intends to evaluate their technique(s) would be used. survey procedures and update language in the LTP (Chapter 5) to discuss (1) criteria for depth of volumetric concrete sampling and (2) high-level overview of the sampling plan and technique to investigate neutron activation in concrete.

8a-vi Discuss the approach for assessing the radiological The licensee and NRC staff discussed the viability of contamination condition of soils adjacent to exterior basement walls leakage through building structures e.g. (cracks) that may and soils beneath basement floor slabs. Particularly contaminate the land areas underneath and directly adjacent to for floor slabs, describe the plan to ensure that these buildings. NRC staff learned that the material surrounding basement soils satisfy release criteria. structures planned to be left onsite is mostly crushed limestone in the berm, as opposed to soil. To date, the licensee has been using professional judgment and historical knowledge (e.g., spills) to perform judgmental surveys of soils underneath buildings.

NRC staff understand that the licensee intends to clarify the approach to soil measurements under and adjacent to building structures for FSS.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 8a-Describe the investigation process planned for the NRC staff learned that the material surrounding basement vii crushed limestone surrounding the basements. structures planned to be left onsite is mostly crushed limestone in Explain how the total dose for backfilled basements the berm, as opposed to soil. The licensee clarified that it will not will be assessed, particularly in the case where reuse onsite material as backfill but rather plans to use offsite either demolition concrete is used that has not been material as backfill. There was a discussion on the definition of quantitatively assessed or soil is placed from a Class backfill, specifically related to native soil (e.g., excavation spoils to 2 or 3 area where there may be some residual be returned to the same area) vs. soil originating offsite. NRC staff contamination. acknowledged that soil from an excavation that is replaced in the same location is not considered "backfill" material, based on how the licensee defines the term "backfill" in the LTP. NRC staff Describe the procedure for scanning and sampling discussed the importance of record keeping of actions related to 10b-i of excavation floor and wall surfaces. refilling and backfilling excavations of buried material, including position (x, y, z) location for sampling locations.

NRC staff understand that the licensee intends to include its approach to surveying crushed limestone for FSS and evaluate the definition of the term "backfill" in the LTP as it relates to offsite soil vs. replacing native soil from an excavation. NRC staff understand that the licensee intends to evaluate the relevancy of Enclosure 18 (Letter to the State of Florida) to the LTP, specifically with reference to "Specific End State Condition 3" that discusses the reuse concrete debris onsite. NRC staff understand that the licensee intends to include information of the FSS survey plans for excavations prior to backfill, including a commitment to perform FSS commensurate with the level of contamination of the buried material that is being removed.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 8b-i For buried piping that will remain onsite at license NRC staff discussed that the current LTP contains some information termination, discuss the following: on survey techniques for inaccessible areas. NRC staff identified ii

• methodology for determining piping LTP Sections 5.4.4.3 (which references the development of a instrumentation sensitivities that are directly separate FSS plan) and LTP 5.4.5.4.8 (FSS of inaccessible areas) comparable to the DCGL, that include conflicting information on FSS of buried piping. LTP iii

• calibration process for instrumentation used Section 5.3.6.3.2 commits to submitting a technical basis document in piping surveys, to develop buried piping DCGLs if certain criteria are met.

iv

• Survey protocol and how the percent survey coverage will be determined for Class 2 and NRC staff understand that the licensee intends to evaluate certain Class 3 piping, portions of the LTP to ensure consistency about information related v

• sample analysis plan for pipe scale and to FSS of buried piping. The licensee will provide more detailed sediment and smears, information on its FSS survey plan and techniques for accessible

• how inaccessible areas of embedded and and inaccessible areas of buried piping. NRC staff understand that vi buried piping will be assessed and describe the licensee intends to consider the information presented in the the plans to characterize and release piping if discussion topics to inform the language related to the FSS plan in it cannot access areas to be surveyed, the LTP.

vii

• Criteria for determining when embedded piping DCGLs are required, and NRC staff discussed the implications of accounting for the dose

• Approach for changing the overall dose from developing buried piping to the overall dose compliance compliance if piping DCGLs were to be equation. This discussion topic, in part, resulted in the issuance of developed. CRCLT RAI-1 Approach to Dose Criterion Compliance Demonstration 9a Describe how radiological surveys and samples NRC staff learned that the licensee does not plan to reuse concrete would be performed to provide reasonable as backfill. NRC staff understand the licensee intends to remove assurance that plant-derived radionuclides from language related to reuse of concrete or debris from Section 1.3.3 of rubblized concrete used as backfill are detectable. the LTP.

Include in this discussion how these radionuclides from the concrete debris designated for reuse will be factored into the assigned dose contributions.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 10a-Discuss the process for determining when The NRC staff learned biased sampling of soil during FSS will be ii judgmental sampling will be conducted at locations based on professional judgement, audible indications, and where residual radioactivity is identified during static investigation levels. Any activity found in the top six inches of soil and scanning measurements. will result in further investigation of the area.

NRC staff understand the licensee intends to provide an update to Section 5.4.3 of the LTP to clarify when judgmental soil samples are collected and the basis for that determination.

10a-Under what conditions will roadways be surveyed to The NRC staff learned that pre-and post-surveys occur along the v verify residual radioactivity has not been introduced haul path for major evolutions (e.g., transport of the reactor vessel during ingress and egress activities? segments) along with routine periodic surveys. The licensee conducts weekly inspections of the CREC to identify conditions potentially impacting decommissioning and to collect judgmental samples, when necessary. NRC staff learned the coal plant regrades portions of roads on a weekly basis, which presents challenges to FSS in these areas.

NRC staff understand the licensee intends to supplement language in the LTP to discuss the routine surveillance program for the CREC, haul paths, and post-FSS survey units.

10c-i Explain the criteria for performing subsurface soil The NRC staff learned subsurface sampling is dependent on contamination investigations and how this will be locations of known spills as indicated in the historical site conducted. assessment. The NRC staff informed the licensee subsurface sampling should be considered for areas of known radiological activities, such as the power block.

Actions associated with the topic above are documented under CCRLT-3a.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 10c-Discuss the justification for limiting the maximum NRC staff learned subsurface soil sampling is not limited to a depth ii depth of planned subsurface soil sampling and of 1 meter. Contamination will be followed until the concentration is investigation to one meter. below established criteria. For example, at some locations, soil has been sampled down to a depth of 8 to 9 feet.

NRC staff understand the licensee intends to explain the protocol for subsurface soil investigations replacing the LTP language about sampling to a depth of 1 meter with criteria for determining the depth of sampling.

10d-i Explain the measurement and sampling The NRC staff learned from the licensee all soils for backfill will be methodology used to ensure soils planned for reuse taken from clean soil approximately 15 miles east of the plant. The do not contain residual radioactivity greater than the licensee conducted an initial survey and sampling campaign to release criteria. How will sample numbers be verify the soil was clean; however, no additional sampling is determined? planned. The number of samples was determined based on professional judgment. NRC staff reviewed SMG Off-site Backfill Characterization Worksheet, which contained the survey plan for offsite backfill soils. The procedure indicated the licensee conducted gamma scans to identify areas of elevated activity for further investigation and sampling. In addition, the criteria for use of soil as backfill was based on whether the soil contained residual radioactivity at levels less than those of the offsite background study conducted as a part of the licensees previous partial site release.

The survey plan includes provisions for analysis of the full suite of radionuclides.

NRC staff understand the licensee intends to include a discussion in the LTP on the survey and sampling of offsite backfill soils before use. Additionally, the licensee intends to provide survey and sampling results for offsite backfill soil completed to date.

10d-Describe the criteria for determining when a bulk NRC staff learned the licensee uses bulk monitors such as portal ii monitoring technical basis will be developed and and truck monitors for qualitative screening only. NRC staff provided to NRC staff for review. understand the licensee intends to remove references to the use of bulk monitoring for soils during FSS from the LTP.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 11a Define the criteria for use of double sampling, NRC staff learned that the licensee will not conduct double sampling including the classification of survey units for which during final status survey. The NRC staff understands the licensee double sampling will be employed. intends to remove references to double sampling from the LTP.

11b Explain how the increase in the probability of a Type I error will be justified for double sampling.

12a Explain whether the licensee plans to perform a NRC staff and the licensee discussed plans for further identification secondary evaluation of insignificant contributors to and deselection of insignificant contributors. NRC staff learned that reduce the ROCs further than was originally the licensee is working on data tables that provide radionuclide proposed in the LTP and how this will be performed. fractions. The licensee plans to perform a secondary evaluation of insignificant contributors, which may take weeks to months. NRC Discuss supporting information obtained from the staff emphasized the need for a minimum number of samples for 12c characterization data results that corroborate the statistical significance in determining ICs and the need for theoretical analysis conducted in Enclosure 5 for continuing verification of ICs through the completion of FSS (i.e.,

determining insignificant contributors. typically 10%).

Describe how the relative nuclide fractions/mixtures This discussion topic resulted in the issuance of RAI FSS-1 12d are determined, how these fractions will be utilized, Insignificant Contributors.

and how these fractions will be verified throughout the characterization, remediation, and FSS process.

12e Explain the process for considering radionuclide NRC staff learned the licensee plans to apply the Oak Ridge results with values less than the minimum detectable Institute for Science and Education method for handling negative concentration and negative values in the and less than MDC values when determining radionuclide fractions.

determination of radionuclide mixtures. The NRC staff discussed the applicability of this approach for the Wilcoxon Rank Sum test, highlighted the need for all negatives to be averaged as zeros when considering dose.

NRC staff understand the licensee intends to provide a discussion of how negative and less than MDC values are addressed when determining radionuclide mixtures.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 13a Please discuss the following information related to NRC staff learned that the licensee has not performed volumetric volumetric concrete measurements: concrete measurements at Unit 3. The information referenced in the

• Volumetric sampling results from January 2020 Scoping Surveys was related to limited volumetric characterization efforts including but not measurements taken from Units 1 and 2. Throughout limited to the January 2020 Scoping Surveys characterization efforts and during FSS, the licensee has been and

• Validity of this surveying approach for FSS will apply MARSSIM techniques for volumetric cores with direct and 13b purposes, including technical precedent, if scanning measurements.

any.

There is no further action for NRC staff or the licensee at this time.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path 14a The LTP notes that soil DCGLs are applicable to NRC staff and the licensee discussed RESRAD-ONSITE model surveys of pavement-covered areas and shallow assumptions in the development of soil DCGLs and their concrete slabs, please clarify the following: applicability to paved areas. NRC staff and the licensee discussed

• Expand upon the claim that the exposure environmental factors (rainfall and runoff) and material properties scenario is most similar to direct radiation (radionuclide transport in soil vs. asphalt). NRC staff noted that the from surface soil. Discuss dominant LTP only has one sentence to justify the use of soil DCGLs for pathways and other pathway contributions paved areas which indicates that the direct exposure pathway is from applying the conceptual model for soils dominant without supporting justification (i.e., analysis, calculations, rather than building structures etc.). NRC staff requested an analysis of these differences with a 14b

• Explain the types of measurements and more detailed pathway analysis.

specific approaches for final status surveys planned for concrete/asphalt roadways, This discussion topic, in part, resulted in the issuance of CRCLT including: RAI-1 Approach to Dose Criterion Compliance Demonstration and o Explanation of how the licensee will CRCLT RAI-4 Applicability or Conservativism of DCGLs for account for different densities of soil Pavement-Covered Areas and Shallow Concrete Slabs.

vs. concrete, and o Dose modeling assumptions that are The licensee discussed their current FSS plans for paved areas and similar and different between the 2 concrete slabs, which included additional investigation if a statistical materials. measurement lands on the asphalt (core bore into asphalt and soil).

14c

• Explain the types of measurements and Additionally, the discussion included the types of surveys (e.g.,

specific approaches for final status surveys scanning, smears), location of scanning and measurements, and planned for the soils underneath paved types of measurements (biased vs. systematic sampling) during areas. FSS. The licensee noted that soil below the asphalt will be 14d

• Provide clarity on the locations of paved surveyed, as well.

areas on the maps provided in Chapter 2. NRC staff and the licensee discussed the plausibility of creating

separate survey units for the pavement/slab and soil areas. If the Survey and sampling methodology for paved and licensee plans to separate paved areas into separate survey units, shallow concrete slabs: NRC staff understand that the licensee will provide maps of those survey units as part of Chapter 2 of the LTP. NRC staff noted that 10a-i Clarify whether the survey and sampling the current LTP does not denote which pavement-covered areas methodology for Class 1 and Class 2 involve and shallow concrete slabs will remain onsite at license termination.

systematic sampling with a random starting point for This discussion topic resulted in the issuance of RAI FSS-4: FSS surface soils. Clarify whether the survey and Plans for Pavement-Covered Areas and Shallow Concrete Slabs.

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No. Discussion Topic NRC Staff Observations & Proposed Closure Path sampling methodology for Class 3 involves random measurement patterns for surface soils.

iii Clarify whether alpha survey measurements will be conducted for pavement covered areas and shallow concrete slabs.

iv Discuss any volumetric sampling to be conducted for pavement covered areas and shallow concrete slabs.

Final status survey program quality assurance. The NRC staff and the licensee discussed including summaries of decommissioning activities effecting quality. For example:

• Written procedures

• Training and qualification

• Measurement and data acquisition

• Instrument selection, calibration, and operation

• Chain of custody

• Control of consumables (e.g., containers, tools)

• Database control and management.

NRC staff and the licensee discussed inclusion of the measurement/data acquisition process which addresses replicate measurements and surveys, duplicate and split samples, field blanks and spikes, and quality control (QC) investigations. NRC staff learned from the licensee that the QC information is contained in the survey plans.

NRC staff understand the licensee intends to update Section 5.8, Final Status Survey Program Quality of the LTP.

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