ML22122A230

Approval to Release Class 2 and Class 3 Survey Units from the Part 50 License

ML22122A230
Person / Time
Site:	La Crosse  File:Dairyland Power Cooperative icon.png
Issue date:	05/24/2022
From:	John Marshall NRC/NMSS/DDUWP/URMDB
To:	Sauger J Energy Solutions
Doell M
References
EPID L-2019-LIT-0000
Download: ML22122A230 (54)

Text

J. Sauger UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 24, 2022 Mr. John Sauger President and Chief Nuclear Officer Reactor D & D EnergySolutions, LLC 121 W. Trade Street, Suite 2700 Charlotte, NC 28202

SUBJECT:

LA CROSSE BOILING WATER REACTOR - RELEASE OF CERTAIN CLASS 1, 2, AND 3 SURVEY UNITS FROM POSSESSION ONLY LICENSE NO. DPR-45 BASED ON THE FINAL STATUS SURVEY REPORT AND SUPPORTING INFORMATION (CAC 000083; EPID L-2019-DF1-0003 AND EPID L-2019-LIT-0000)

Dear Mr. Sauger:

By letters dated September 11, 2019, December 13, 2019, and January 28, 2020, as supplemented by letter dated November 2, 2020, LaCrosseSolutions, LLC (LS, the licensee) requested U.S. Nuclear Regulatory Commission (NRC) review of the Final Status Survey Report (FSSR) for the La Crosse Boiling Water Reactor (LACBWR). These submittals support the LACBWR partial site release request received on February 14, 2020, which would remove a 36.5 acre portion of the site from the LACBWR License, No. DPR-45, which was issued pursuant to Part 50, Domestic Licensing of Production and Utilization Facilities, of Title 10 of the Code of Federal Regulations (10 CFR). Subsequently, in a letter dated December 14, 2021, LaCrosseSolutions requested that the NRC staff expedite review of the FSSR documentation related to the LACBWR Class 2 and Class 3 survey units and approve the release of those survey units from the 10 CFR Part 50 license in advance of the Class 1 survey units.

The Class 2 and Class 3 survey units consist of eight above grade building survey units, seven open land survey units, and nine buried piping survey units for a total of 24 survey units. The NRC staff also evaluated one Class 1 buried piping survey unit in the scope of this review in order to be able to include all of the LACBWR buried piping survey units as part of the partial site release. The FSSR is the documentation that demonstrates completion of the activities described in the LACBWR License Termination Plan (LTP), which was submitted by letter dated June 27, 2016. The LACBWR LTP was approved by the NRC on May 21, 2019.

The LACBWR LTP provided the details of the plan for characterizing, identifying, and remediating the remaining residual radioactivity at the LACBWR site to a level that will allow the site to be released for unrestricted use. The LACBWR LTP also described how the licensee will confirm the extent and success of remediation through radiological surveys, as captured in the FSSR, provide financial assurance to complete decommissioning, and ensure the environmental impacts of the decommissioning activities are within the scope originally envisioned in the associated environmental documents.

J. Sauger The NRC staff has completed its review of the portions of the LACBWR FSSR associated with removing 25 survey units from the LACBWR 10 CFR Part 50 license: 24 Class 2 and Class 3 survey units and the sole Class 1 buried piping survey unit. The NRC staffs review considered if the FSSR for these survey units is in accordance with the criteria in 10 CFR 50.82(a)(11):

whether the remediation of these survey units is in accordance with the approved LTP and whether these survey units meet the criteria for unrestricted release in Subpart E, Radiological Criteria for License Termination, of 10 CFR Part 20, Standards for Protection Against Radiation. The radiological dose contributions associated with these 25 survey units will be evaluated in aggregate with the remaining LACBWR Class 1 survey units to ensure that the site, as a whole, meets the criteria for unrestricted release as a part of the final license termination decision; this evaluation will be documented in a separate letter.

The NRC staff reviewed the portions of the LACBWR FSSR associated with the Class 2 and Class 3 survey units, as well as the Class 1 buried piping survey unit. The licensees Final Status Survey (FSS) design criteria, implementation of the Data Quality Objectives (DQO) process, and survey approach/methods were reviewed, and results were assessed against the licensees approved release criteria. Based on this review, the NRC determined that the LACBWR Class 2 and Class 3 survey units, and the Class 1 buried piping survey unit, meet the criteria in 10 CFR 50.82(a)(11). Therefore, the NRC staff finds the release of the Class 2 and Class 3 survey units, and the Class 1 buried piping survey unit, to be acceptable and releases these survey units from the license. Following their removal from the license, in the unlikely event the released areas were to become radiologically contaminated as a result of later decommissioning activities at the Independent Spent Fuel Storage Installation (ISFSI), the contamination would be considered an offsite release, and subject to 10 CFR Part 20.

The enclosure to this letter contains a summary of the NRC staffs evaluation and analysis of the portions of the LACBWR FSSR associated with the Class 2 and Class 3 survey units, as well as the sole Class 1 buried piping survey unit, and supports the determination that these 25 survey units may be released from the LACBWR 10 CFR Part 50 license.

The staff also reviewed the residual radioactivity values in the LACBWR FSSR and compared them to the trigger values in the 2002 Memorandum of Understanding (MOU) between the NRC and the U.S. Environmental Protection Agency (EPA) entitled Consultation and Finality on Decommissioning and Decontamination of Contaminated Sites. Based on this review, the residual radioactivity in soil and groundwater at the site do not exceed the trigger values in the MOU and, as such, Level 2 consultation with EPA in accordance with the MOU is not required.

In accordance with 10 CFR 2.390 of the NRCs Agency Rules of Practice and Procedure, a copy of this letter will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records component of NRCs Agencywide Documents Access and Management System (ADAMS). ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html.

J. Sauger If you have any questions concerning this evaluation, please contact me or Marlayna Doell, the LACBWR Project Manager, at (301) 415-3178 or via email at marlayna.doell@nrc.gov.

Sincerely, Signed by Marshall, Jane on 05/24/22 Jane E. Marshall, Director Division of Decommissioning, Uranium Recovery, and Waste Programs Office of Nuclear Material Safety and Safeguards Docket Nos.: 50-409 and 72-046 License No.: DPR-45

Enclosure:

Safety Evaluation of Final Status Survey Report for LACBWR Class 2 and Class 3 Survey Units cc w/enclosure: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 U.S. NUCLEAR REGULATORY COMMISSION EVALUATION BY THE OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS OF THE CLASS 2 AND CLASS 3 FINAL STATUS SURVEY REPORTS RELATED TO A PARTIAL SITE RELEASE REQUEST FOR POSSESSION ONLY LICENSE NO. DPR-45 LACROSSESOLUTIONS, LLC LA CROSSE BOILING WATER REACTOR DOCKET NO. 50-409

1.0 INTRODUCTION

By letters dated September 11, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19261A344), December 13, 2019 (ADAMS Accession No. ML20006D756), and January 28, 2020 (ADAMS Accession No. ML20031C839), as supplemented by letter dated November 2, 2020 (ADAMS Accession No. ML20356A041),

LaCrosseSolutions, LLC (LS, the licensee) requested U.S. Nuclear Regulatory Commission (NRC) review of the Final Status Survey Report (FSSR) for the La Crosse Boiling Water Reactor (LACBWR). These submittals support the LACBWR partial site release request received on February 14, 2020 (ADAMS Accession No. ML20052D015), which would remove a 36.5 acre portion of the site from the LACBWR License No. DPR-45, which was issued pursuant to Part 50, Domestic Licensing of Production and Utilization Facilities, of Title 10 of the Code of Federal Regulations (10 CFR). Subsequently, in a letter dated December 14, 2021 (ADAMS Accession No. ML21350A014), LaCrosseSolutions requested that the NRC staff expedite review of the FSSR documentation related to the LACBWR Class 2 and Class 3 survey units and approve the release of those survey units from the 10 CFR Part 50 license in advance of the Class 1 survey units.

The Class 2 and Class 3 survey units consist of eight above grade building survey units, seven open land survey units, and nine buried piping survey units, for a total of 24 survey units. The NRC staff also evaluated one Class 1 buried piping survey unit in the scope of this review in order to be able to include all of the LACBWR buried piping survey units as part of the partial site release. The FSSR is the documentation that demonstrates completion of the activities described in the LACBWR License Termination Plan (LTP), which was submitted by letter dated June 27, 2016 (ADAMS Accession No. ML16200A095), as supplemented by letter dated December 1, 2016 (ADAMS Accession No. ML16347A025). The LACBWR LTP was approved by the NRC on May 21, 2019 (ADAMS Accession No. ML19008A079). Associated references to the LTP Safety Evaluation Report are also available (ADAMS Accession No. ML19007A031).

Enclosure

The LACBWR LTP supplied the details of the plan for characterizing, identifying, and remediating the remaining residual radioactivity at the LACBWR site to a level that will allow the site to be released for unrestricted use. The LACBWR LTP also described how the licensee will confirm the extent and success of remediation through radiological surveys, as captured in the FSSR, provide financial assurance to complete decommissioning, and ensure the environmental impacts of the decommissioning activities are within the scope originally envisioned in the associated environmental documents.

The NRC staff has completed a review of the portions of the LACBWR FSSR associated with the Class 2 and Class 3 survey units, as well as the Class 1 buried piping survey unit. The licensees Final Status Survey (FSS) design criteria, implementation of the Data Quality Objectives (DQO) process, and survey approach/methods included in the FSSR were reviewed, and results were assessed against the approved release criteria from the LACBWR LTP.

2.0 FACILITY BACKGROUND LACBWR was an Atomic Energy Commission (AEC) Demonstration Project Reactor that first went critical in 1967, commenced commercial operation in November 1969, and was capable of producing 50 megawatts of electricity. LACBWR is located on the east bank of the Mississippi River in Vernon County, Wisconsin, about 1 mile south of the Village of Genoa, Wisconsin and approximately 19 miles south of the city of La Crosse, Wisconsin, and is co-located with the Genoa Generating Station (Genoa 3), which is a coal-fired power plant that is slated for decommissioning beginning in the summer of 2022. The Allis Chalmers Company was the original licensee of LACBWR; the AEC later sold the plant to the Dairyland Power Cooperative (DPC) and granted it Provisional Operating License No. DPR-45 on August 28, 1973 (ADAMS Accession No. ML17080A423).

LACBWR permanently ceased operations on April 30, 1987 (ADAMS Accession No. ML17080A422), and reactor defueling was completed on June 11, 1987 (ADAMS Accession No. ML17080A420). In a letter dated August 4, 1987 (ADAMS Accession No. ML17080A393), the NRC terminated DPCs authority to operate LACBWR under Provisional Operating License No. DPR-45 and granted the licensees request to amend the license to a possess-but-not-operate status. By letter dated August 18, 1988 (ADAMS Accession No. ML17080A421), the NRC amended DPCs Provisional Operating License No.

DPR-45 to Possession Only License No. DPR-45 to reflect the permanently defueled configuration at LACBWR. Therefore, pursuant to Paragraphs (a)(1)(iii) and (a)(2) in 10 CFR 50.82, Termination of license, Possession Only License DPR-45 does not authorize operation of LACBWR or emplacement or retention of fuel into the reactor vessel.

The NRC issued an order to authorize decommissioning of LACBWR and approve the licensees proposed Decommissioning Plan (DP) on August 7, 1991 (ADAMS Accession No. ML17080A454). Because the NRC approved DPCs DP before August 28, 1996 (the effective date of an NRC final rule concerning reactor decommissioning (61 FR 39278; July 29, 1996)), the DP is considered the Post-Shutdown Decommissioning Activities Report (PSDAR) for LACBWR. The PSDAR public meeting was held on May 13, 1998, and subsequent updates to the LACBWR decommissioning report have combined the DP and PSDAR into the LACBWR Decommissioning Plan and Post-Shutdown Decommissioning Activities Report. This document is also considered the Final Safety Analysis Report and Defueled Safety Analysis Report for LACBWR and is updated every 24 months in accordance with Paragraph (e) of 10 CFR 50.71, Maintenance of records, making of reports. DPC constructed an onsite independent spent fuel storage installation (ISFSI) under its 10 CFR Part 72, Licensing

Requirements for the Independent Storage of Spent Nuclear Fuel, High Level Radioactive Waste, and Reactor-Related Greater than Class C Waste, general license, and completed the movement of all 333 spent nuclear fuel elements to dry cask storage at the ISFSI by September 19, 2012 (ADAMS Accession No. ML12290A027).

By order dated May 20, 2016 (ADAMS Accession No. ML16123A073), the NRC approved the direct transfer of Possession Only License No. DPR-45 for LACBWR from DPC to LS, a wholly-owned subsidiary of EnergySolutions, LLC, which was created for the sole purpose of completing the dismantlement and remediation activities at the LACBWR site. The order was published in the Federal Register (FR) on June 2, 2016 (81 FR 35383). The transfer assigned DPCs licensed possession, maintenance, and decommissioning authorities for LACBWR to LS to implement expedited decommissioning at the LACBWR site. LS commenced decommissioning of the site effective June 1, 2016, and completed all activities necessary to terminate the license and propose release of the majority of the site for unrestricted use as an industrial site, as documented in the associated LACBWR FSSR, except for a small area surrounding the ISFSI until final disposition and removal of the spent nuclear fuel.

By order dated September 24, 2019 (ADAMS Accession No. ML19008A393), the NRC approved the transfer of Possession Only License No. DPR-45 for LACBWR from LS back to DPC and approved a conforming license amendment. The transfer order will be implemented upon completion of decommissioning activities at the LACBWR site and is currently effective through September 24, 2022 (three years from issuance, with extensions). Specifically, by letter dated June 24, 2020 (ADAMS Accession No. ML20188A228), LS submitted a request to extend the effectiveness of the transfer order by six months. By order dated September 1, 2020 (First Extension Order) (ADAMS Accession No. ML20195A846), the NRC extended the order's expiration date to March 24, 2021. Subsequently, by letter dated February 2, 2021 (ADAMS Accession No. ML21036A055), LS submitted a request to extend the effectiveness of the order by an additional six months. By order dated March 9, 2021 (Second Extension Order) (ADAMS Accession No. ML21050A299), the NRC extended the order's expiration date to September 24, 2021. On August 17, 2021 (ADAMS Accession No. ML21230A330), LS requested a third extension of the effectiveness of the order. By order dated August 30, 2021 (Third Extension Order) (ADAMS Accession No. ML21228A105), the NRC extended the order's expiration date to September 24, 2022. The previously approved conforming license amendment will be issued and made effective when the transfer is complete.

3.0 TECHNICAL EVALUATION

3.1 Applicable Requirements Section 5.11, Final Status Survey (FSS) Reporting, of the LACBWR LTP describes the licensees approach to license termination and FSSR documentation as follows:

Documentation of the FSS will be contained in two types of reports and will be consistent with Section 8.6, Documentation, of NUREG-1575, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), Revision 1, dated August 2000 (ADAMS Accession No. ML082470583). An FSS Release Record will be prepared to provide a complete record of the as-left radiological status of an individual survey unit, relative to the specified release criteria. Survey Unit Release Records will be made available to the NRC for review as appendices to the appropriate FSS Final Report. An FSS Final Report, which is a written report that is provided to the NRC for its review, will be prepared to provide a summary

of the survey results and the overall conclusions which demonstrate that the site, or portions of the site, meets the radiological criteria for unrestricted use including the as low as reasonably achievable (ALARA) criterion.

It is anticipated that the FSS Final Report will be provided to the NRC in phases as remediation and FSS are completed with related portions of the site. The phased approach for submittal is intended to provide the NRC with detailed insight regarding the remediation and FSS activities early in the process, to provide opportunities for improvement based on feedback, and to support a logical and efficient approach for technical review and independent verification.

Additionally, the licensee indicated that it may seek approval to remove areas from the LACBWR license once decommissioning and remediation tasks are complete and the FSSR can demonstrate that release of the area(s) and any associated basement structures, above grade buildings, or buried piping will have no adverse impact on the ability of the site in aggregate to meet the 10 CFR Part 20, Subpart E, criteria for unrestricted release at the time of the final license termination decision. Because the approved LACBWR LTP includes the phased FSSR documentation process set forth above, as well as the fact that removal from the LACBWR 10 CFR Part 50 license of the Class 2 and Class 3 survey units, and sole Class 1 buried piping survey unit, is taking place after NRC approval of the LTP, the 10 CFR 50.83, Release of part of a power reactor facility or site for unrestricted use, partial site release requirements are not applicable to the current review for unrestricted release. However, it should be noted that on April 12, 2017 (ADAMS Accession No. ML16250A200), the NRC approved the partial site release of approximately 88 acres of non-impacted land from the LACBWR license, leaving approximately 75.5 acres under the current LACBWR license.

In accordance with 10 CFR 50.82(a)(11), the LACBWR License Termination Plan, and the NRC safety evaluation dated May 21, 2019, the NRC staff has reviewed the applicable LACBWR FSS release records to ensure that the proposed action will have no impact on the ability of the site in aggregate to meet the unrestricted release criteria in 10 CFR 20.1402, Radiological criteria for unrestricted use. In the LACBWR LTP, the licensee establishes site-specific Base Case Derived Concentration Guideline Levels (DCGLs) for each radionuclide of concern that are each equivalent to a total effective dose equivalent of 25 millirem per year (mrem/year). To ensure that when all the separate source terms are considered jointly, the dose remains below 25 mrem/year, the licensee assigned a fraction of the 25 mrem/year dose to each type of source term (i.e., above ground buildings, buried piping, soil, etc.). The Operational DCGLs represent the site-specific Base Case DCGLs reduced by the appropriate fraction for each type of source term and are used in the LACBWR FSS design.

3.2 Area to be Released The area the licensee proposed to release as part of the December 14, 2021, request consists of 24 survey units, which are the Class 2 and Class 3 survey units, as well as a single Class 1 buried piping survey unit. An FSS was performed for each of these impacted survey units in accordance with the LACBWR LTP, MARSSIM, and numerous LACBWR implementing procedures. The licensee stated that an FSS release record was prepared for each survey unit to provide complete and unambiguous records of the as-left radiological status. Sufficient data and information are provided in each release record to enable an independent recreation and evaluation at some future time of both the survey activities and the derived results.

Figure 1. LACBWR FSSR Phase 1 Survey Unit Locations

Figure 2. LACBWR FSSR Phase 2 Survey Unit Locations

Figure 3. LACBWR FSSR Phase 3 Survey Unit Locations

The FSSR was written consistent with the guidance provided in NUREG-1757, Consolidated Decommissioning Guidance, Volume 2, Characterization, Survey, and Determination of Radiological Criteria, Final Report, Revision 1, dated September 2006 (ADAMS Accession No. ML063000252), and provided in three phases. The Phase 1 LACBWR FSSR (ADAMS Accession No. ML19261A344) was submitted on September 17, 2019, and includes four sub-grade excavation survey units, three open land survey units, and two basement survey units. The Phase 2 LACBWR FSSR (ADAMS Accession No. ML20006D756) was submitted on December 16, 2019, and includes eight above grade building survey units and ten buried piping survey units. The Phase 3 LACBWR FSSR (ADAMS Accession No. ML20031C839) was submitted on January 28, 2020, and includes three sub-grade excavation survey units and 11 open land area survey units. Note that each LACBWR FSSR phase consisted of Class 1, Class 2, and Class 3 survey units, but this evaluation discusses only the Class 2 and Class 3 survey units, and the sole Class 1 buried piping survey unit.

Table 1. LACBWR FSSR Class 2 Survey Units (10 Total Survey Units)

Survey Unit Type Survey Unit Description Phase Class Area North of LACBWR L2-011-101 Open Land 3 2 Site Enclosure (LSE) Fence L2-011-102 Open Land Area South of LSE Fence 1 2 L2-011-103 Open Land Genoa 3 Crib House Surrounding Area 1 2 Genoa 3 Crib House and Circulating L2-011-104 Open Land 3 2 Water Discharge Land Area B2-010-101 Building LACBWR Crib House 2 2 B2-010-102 Building Genoa 3 Crib House 2 2 B2-010-103 Building LACBWR Administration Building 2 2 S2-011-103 A Buried Piping De-Icing Line 2 2 S2-011-103 B Buried Piping Low-Pressure Service Water Piping 2 2 S2-011-103 Buried Piping Circulating Water Intake Pipe 2 2 Table 2. LACBWR FSSR Class 3 Survey Units (14 Total Survey Units)

Survey Unit Type Survey Unit Description Phase Class L3-012-101 Open Land North End of Licensed Site 3 3 L3-012-102 Open Land Transmission Switch Yard 1 3 Plant Access and ISFSI L3-012-109 Open Land 3 3 Haul Road Grounds B3-012-101 Building Back-up Control Center 2 3 B3-012-102 Building Transmission Sub-Station Switch House 2 3 B3-012-103 Building Genoa 1 Crib House 2 3 B3-012-104 Building Barge Wash Break Room 2 3 B3-012-109 Building Security Shack 2 3 S3-012-109 A Buried Piping Storm Drain 1 2 3 S3-012-109 B Buried Piping Storm Drain 2 2 3 S2-011-101 A Buried Piping Storm Drain 3 2 2a S2-011-101 B Buried Piping Storm Drain 6 2 2a S3-012-102 A Buried Piping Storm Drain 4 2 3 S3-012-102 B Buried Piping Storm Drain 5 2 3 a Note that the corresponding table in the LACBWR Phase 2 Final Release Record Report states that Storm Drain 3 and Storm Drain 6 were Class 3, but the release records indicate these were classified as Class 2.

The NRC staff reviewed the portions of the LACBWR FSSR associated with the Class 2 and Class 3 survey units, as well as the Class 1 buried piping survey unit, for consistency with the LACBWR LTP. The Class 2 and Class 3 survey units are summarized in Table 1 and Table 2 above, along with their associated phase of the LACBWR FSSR. The Class 1 buried piping survey unit is the Circulating Water Discharge Pipe, which was a part of Phase 2 of the FSSR.

The NRC staff requested supplemental information associated with several survey units in a request for additional information (RAI) dated August 19, 2020 (ADAMS Accession No. ML20195A272). The licensee responded to this request on November 2, 2020 (ADAMS Accession No. ML20356A041), and the NRC staffs conclusions associated with the Class 2 and Class 3, as well as the Class 1 buried piping, survey units are documented in this report.

The NRC staff compared the licensees decommissioning and FSS activities to applicable decommissioning guidance. This decommissioning guidance includes: MARSSIM; NUREG-1507, Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions, Revision 0, dated June 1998 (ADAMS Accession No. ML003676046), and Revision 1, dated August 2020 (ADAMS Accession No. ML20233A507); NUREG-1700, Standard Review Plan for Evaluating Nuclear Power Reactor License Termination Plans, Revision 1, dated April 2003 (ADAMS Accession No. ML031270391), and Revision 2, dated April 2018 (ADAMS Accession No. ML18116A124);

and NUREG-1757, Volumes 1 and 2, Consolidated Decommissioning Guidance. The NRC staff evaluated the portions of the LACBWR FSSR for each type of Class 2 and Class 3 survey unit (open land area, buried piping (including the sole Class 1 buried piping survey unit), and above grade buildings) in order to ultimately ensure that release of these survey units will have no adverse impact on the ability of the site in aggregate to meet the 10 CFR Part 20, Subpart E, criteria for unrestricted release at the time of the final license termination decision, which will be provided under a separate evaluation.

3.3 Class 2 and Class 3 Open Land Areas 3.3.1 Description of Survey Units The LACBWR site consists of four Class 2 open land area survey units (L2-011-101, L2-011-102, L2-011-103, and L2-011-104) and three Class 3 open land area survey units (L3-012-101, L3-012-102, and L3-012-109), as summarized in Table 3 below.

Table 3. LACBWR Class 2 and Class 3 Open Land Area Survey Units Survey Unit Type Survey Unit Description Phase Class L2-011-101 Open Land Area North of LSE Fence 3 2 L2-011-102 Open Land Area South of LSE Fence 1 2 L2-011-103 Open Land Genoa 3 Crib House Surrounding Area 1 2 Genoa 3 Crib House and Circulating Water L2-011-104 Open Land 3 2 Discharge Land Area L3-012-101 Open Land North End of Licensed Site 3 3 L3-012-102 Open Land Transmission Switch Yard 1 3 L3-012-109 Open Land Plant Access and ISFSI Haul Road Grounds 1 3

Survey Unit L2-011-101, Area North of LSE Fence Survey Unit L2-011-101 is a Class 2 open land survey unit, which consists of open land with a surface area of 5,728 square meters (m2). For survey unit L2-011-101, 25% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 2 specified range of 10-100% for surface soil scans. The survey plan specified a total of fourteen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that fourteen systematic and three judgmental soil samples were taken in the survey unit. In addition, the LACBWR LTP specified that one hard-to-detect (HTD) radionuclide and one quality control (QC) soil sample be taken in the survey unit. The NRC staff verified that two HTD and two QC soil samples were taken in the survey unit.

The licensee stated that the maximum sum of fractions (SOF) for the applicable radionuclides of concern (ROCs) by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.0681 in Survey Unit L2-011-101. The mean SOF when applying the respective Base Case DCGLs for soil is 0.0124 in Survey Unit L2-011-101. This SOF results in a dose for this survey unit of 0.3103mrem/yr. During the Oak Ridge Institute of Science and Education (ORISE) confirmatory survey of this area, ORISE collected six random and two judgmental soil samples based on gamma scan data that demonstrated elevated radiation distinguishable from background. The NRC staff verified that the soil concentrations for all ROCs in the soil samples collected during the ORISE confirmatory survey were less than 50%

of the Operational DCGLs.

Survey Unit L2-011-102, Area South of LSE Fence Survey Unit L2-011-102 is a Class 2 open land survey unit, which consists of open land with a surface area of 2,257 m2. For Survey Unit L2-011-102, 25% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 2 specified range of 10-100% for surface soil scans. The survey plan specified a total of fourteen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that fourteen systematic and eight judgmental soil samples were taken in the survey unit. In addition, the LACBWR LTP specified that two HTD and one QC soil sample be taken in the survey unit.

The NRC staff verified that two HTD and five QC soil samples were taken in the survey unit.

The licensee stated that the maximum SOF for the applicable ROCs by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.0419 in Survey Unit L2-011-102. The mean SOF when applying the respective Base Case DCGLs for soil is 0.0095 in Survey Unit L2-011-102. This SOF results in a dose for this survey unit of 0.2368 mrem/year. During the ORISE confirmatory survey of this area, ORISE collected two random and one judgmental soil sample based on gamma scan data that demonstrated elevated radiation distinguishable from background. The NRC staff verified that the soil concentrations for all ROCs in the soil samples collected during the ORISE confirmatory survey were less than 50% of the Operational DCGLs.

Survey Unit L2-011-103, Genoa 3 Crib House Surrounding Area Survey Unit L2-011-103 is a Class 2 open land survey unit, which consists of open land with a surface area of 2,445 m2. For Survey Unit L2-011-103, 25% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 2 specified range of 10-100% for surface soil scans. The survey plan specified a total of fourteen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that

fourteen systematic and two judgmental soil samples were taken in the survey unit. In addition, the LACBWR LTP specified that one HTD and one QC soil sample be taken in the survey unit.

The NRC staff verified that two HTD and four QC soil samples were taken in the survey unit.

The licensee stated that the maximum SOF of the applicable ROCs by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.0755 in Survey Unit L2-011-103. The mean SOF when applying the respective Base Case DCGLs for soil is 0.0097 in Survey Unit L2-011-103. This SOF results in a dose for this survey unit of 0.2416 mrem/year. During the ORISE confirmatory survey of this area, ORISE collected one random and one judgmental soil sample based on gamma scan data that demonstrated elevated radiation distinguishable from background. The NRC staff verified that the soil concentrations for all ROCs in the soil samples collected during the ORISE confirmatory survey were less than 50% of the Operational DCGLs.

Survey Unit L2-011-104, Genoa 3 Crib House and Circulating Water Discharge Land Area Survey Unit L2-011-104 is a Class 2 open land survey unit, which consists of open land with a surface area of 5,285 m2. For Survey Unit L2-011-104, 25% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 2 specified range of 10-100% for surface soil scans. The survey plan specified a total of fourteen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that fourteen systematic and eight judgmental soil samples were taken in the survey unit. In addition, the LACBWR LTP specified that one HTD and one QC soil sample be taken in the survey unit.

The NRC staff verified that three HTD and four QC soil samples were taken in the survey unit.

The licensee stated that the maximum SOF of the applicable ROCs by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.0569 in Survey Unit L2-011-104. The mean SOF when applying the respective Base Case DCGLs for soil is 0.0102 in Survey Unit L2-011-104. This SOF results in a dose for this survey unit of 0.2557 mrem/year. During the ORISE confirmatory survey of this area, ORISE collected two random and one judgmental soil sample based on gamma scan data that demonstrated elevated radiation distinguishable from background. The NRC staff verified that the soil concentrations for all ROCs in the soil samples collected during the ORISE confirmatory survey were less than 50% of the Operational DCGLs.

Survey Unit L3-012-101, North End of Licensed Site Survey Unit L3-012-101 is a Class 3 open land survey unit, which consists of open land with a surface area of 5,285 m2. For Survey Unit L3-012-101, 10% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 3 judgmental criteria for surface soil scans. The survey plan specified a total of fourteen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that fourteen systematic and two judgmental soil samples were taken in the survey unit. In addition, the LACBWR LTP specified that two HTD and one QC soil sample be taken in the survey unit.

The NRC staff verified that three HTD and two QC soil samples were taken in the survey unit.

The licensee stated that the maximum SOF of the applicable ROCs by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.0788 in Survey Unit L3-012-101. The mean SOF when applying the respective Base Case DCGLs for soil is 0.0148 in Survey Unit L3-012-101. This SOF results in a dose for this survey unit of 0.3699 mrem/year. During the ORISE confirmatory survey of this area, ORISE collected four

random and seven judgmental soil samples based on gamma scan data that demonstrated elevated radiation distinguishable from background. The NRC staff verified that the soil concentrations for all ROCs in the soil samples collected during the ORISE confirmatory survey were less than 50% of the Operational DCGLs.

Survey Unit L3-012-102, Transmission Switch Yard Survey Unit L3-012-102 is a Class 3 open land survey unit, which consists of open land with a surface area of 11,711 m2. For Survey Unit L3-012-102, 10% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 3 judgmental criteria for surface soil scans. The survey plan specified a total of seventeen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that 28 systematic and two judgmental soil samples were taken in the survey unit. In addition, the LTP specified that two HTD and one QC soil sample be taken in the survey unit. The NRC staff verified that three HTD and two QC soil samples were taken in the survey unit.

The licensee stated that the maximum SOF of the applicable ROCs by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.0514 in Survey Unit L3-012-102. The mean SOF when applying the respective Base Case DCGLs for soil is 0.009 in Survey Unit L3-012-102. This SOF results in a dose for this survey unit of 0.2247 mrem/year. During the ORISE confirmatory survey of this area, ORISE did not obtain any soil samples in this survey unit due to the presence of ceramic and other naturally occurring radioactive material, as well as energized equipment in the survey unit. However, ORISE was able to perform a gamma walkover scan of judgmental areas over a portion of the survey unit.

Survey Unit L3-012-109, Plant Access and ISFSI Haul Road Grounds Survey Unit L3-012-109 is a Class 3 open land survey unit, which consists of open land with a surface area of 28,187 m2. For Survey Unit L3-012-109, 10% of the total surface area was selected for surface soil scans, which is consistent with the MARSSIM Class 3 judgmental criteria for surface soil scans. The survey plan specified a total of fourteen systematic soil samples and one judgmental sample be taken in the survey unit. The NRC staff verified that fourteen systematic and four judgmental soil samples were taken in the survey unit. In addition, the LACBWR LTP specified that one HTD and one QC soil sample be taken in the survey unit.

The NRC staff verified that five HTD and six QC soil samples were taken in the survey unit.

The licensee stated that the maximum SOF of the applicable ROCs by direct measurement or inference when applying the respective Operational DCGLs for soil is 0.1119 in Survey Unit L3-012-109. The mean SOF when applying the respective Base Case DCGLs for soil is 0.0176 in Survey Unit L3-012-109. This SOF results in a dose for this survey unit of 0.4389 mrem/year. During the ORISE confirmatory survey of this area, ORISE collected six random and two judgmental soil samples based on gamma scan data that demonstrated elevated radiation distinguishable from background. The NRC staff verified that the soil concentrations for all ROCs in the soil samples collected during the ORISE confirmatory survey were less than 50% of the Operational DCGLs.

3.3.2 NRC Evaluation of Class 2 and Class 3 Open Land Survey Areas The NRC staff verified that the results of the LACBWR FSS demonstrate that the Class 2 and Class 3 open land area survey units meet the radiological criteria for license termination and may therefore be released from the LACBWR 10 CFR Part 50 license. Specifically, the NRC

staff reviewed the adequacy of the survey methods and instrumentation, the sufficiency of the number of samples collected, the quality control program, the comparison of the results to the release criteria, and the results of the statistical test to demonstrate compliance. A discussion of the specific topics that received an in-depth review are presented below.

3.3.2.1 Survey Scan Coverage The purpose of scanning during FSS is to identify locations within the survey unit that exceed the investigation levels established in the LTP. These locations are intended to be marked and receive additional investigations to determine the concentration, area, and extent of the radiological contamination. The LACBWR LTP indicates that MARSSIM Table 5.9, Recommended Survey Coverage for Structures and Land Areas, was utilized to determine the recommended survey coverage for open land areas, and the amount of area to be covered by scan measurements is provided in Table 5-15, Recommended Survey Coverage for Open Land Areas and Structures, of the LACBWR LTP.

In accordance with the guidance contained in MARSSIM, Class 2 survey units require 10-100%

surface soil scan coverage. Each of the four LACBWR Class 2 open land area survey units received surface soil scans of 25% of the total surface area. MARSSIM does not specify a minimum scan coverage requirement for Class 3 survey units; instead, the guidance states that judgmental scans should be performed on areas that are most likely to indicate potential radiological contamination. Each of the three LACBWR Class 3 open land area survey units received judgmental surface soil scans of 10% of the total surface area. For the LACBWR Class 2 and Class 3 open land area survey units, the associated FSS release records indicate that gridded areas were determined within each survey unit to support scanning of the surface soil, and the surveys were performed using serpentine-like scans with the detector within three inches of the surface at a speed of 0.5 meters per second over the scan lanes in gridded areas.

Table 6.3 Radiation Detectors with Applications to Gamma Surveys, of MARSSIM Section 6.5.3, Instrument Selection, provides guidance on radiation detection instrumentation applicable to, and appropriate for, conducting FSS. The instrumentation selected by the licensee to perform scan surveys of the open land area survey units is the Ludlum 44-10 sodium iodide (NaI) gamma scintillation detector coupled with the Model 2350-1 rate meter/scaler/data logger. This instrumentation is consistent with the guidance contained in MARSSIM regarding appropriate radiation detection instrumentation for use during FSS.

Based on the above considerations, the NRC staff finds that the licensees approach to conducting scan coverage for the LACBWR Class 2 and Class 3 open land area survey units, as demonstrated in the FSS release records for these survey units, is consistent with the applicable MARSSIM guidance, and aligns with the associated discussion in Section 5.6.4.4, Scan Coverage, of the NRC-approved LACBWR LTP. Therefore, the scan coverage for the LACBWR Class 2 and Class 3 open land area survey units is acceptable.

3.3.2.2 Detector Efficiency and Scan Minimum Detectable Concentration (MDC)

Section 6.7.2.1, Scanning for Beta and Gamma Emitters, of MARSSIM and Section 6.2.5, A Priori Scan MDCs for Land Areas, of NUREG-1507, Revision 1, provide guidance on scan MDCs for open land areas. LACBWR Technical Support Document (TSD) RS-TD-313196-006, Ludlum Model 44-10 Detector Sensitivity, Revision 0 (ADAMS Accession No. ML19007A044),

evaluates the sensitivity of the Ludlum 44-10 NaI radiation detector used to scan the LACBWR Class 2 and Class 3 open land areas. The manufacturers published sensitivity for the

Ludlum 44-10 detector is 900 counts per minute per microroentgen per hour (cpm/microR/hr) for cesium-137 (Cs-137), and 430 cpm/microR/hr for cobalt-60 (Co-60). This corresponds to the sensitivity for Cs-137 and Co-60 listed in Table 6.7, NaI Scintillation Detector Scan MDCs for Common Radiological Contaminants, of MARSSIM. The TSD also states that the NaI scan MDC uses the formulas and approach contained in the MARSSIM and NUREG-1507 guidance.

While the manufacturers published sensitivity is 900 cpm/microR/hr for Cs-137, the TSD applied a conversion factor of 940 cpm/microR/hr as the detector sensitivity for Cs-137, which was derived empirically from a study described in the report. The NRC staff assessed the safety significance of this difference on the calculated scan MDCs for open land areas and determined that it is not significant and will not impact compliance with the unrestricted release criteria for these survey units. Specifically, this difference would cause the licensee to use a scan action level that is slightly lower than what would be used if the manufacturers published sensitivity of 900 cpm/microR/hr instead of 940 cpm/microR/hr was applied as the detector sensitivity for Cs-137. Therefore, this difference in terms of the scan action level is conservative. When assessing the associated scan MDC values, the NRC staff noted that if the manufacturers sensitivity had been used as the detector sensitivity for Cs-137, the calculated scan MDC values would have been slightly larger. However, since the scan MDC values using the manufacturers sensitivity are still below 50% of the Operational DCGLs established for the LACBWR open land areas, the difference does not affect compliance with the release criteria.

Based on the above considerations, the NRC staff finds that the licensees approach to detector efficiency and scan MDCs for the LACBWR Class 2 and Class 3 open land area survey units, as demonstrated in the FSS release records for these survey units, is consistent with the applicable MARSSIM and NUREG-1507 guidance and aligns with the associated discussion in the NRC-approved LACBWR LTP. Therefore, the detector efficiency and scan MDCs for the LACBWR Class 2 and Class 3 open land area survey units are acceptable.

3.3.2.3 Background Radiation Measurements The radionuclides of concern for the LACBWR Class 2 and Class 3 open land areas are Cs-137, Co-60, strontium-90 (Sr-90), europium-152 (Eu-152), and europium-154 (Eu-154). The licensee determined the average background radiation for the FSS surface scans using the average of five 1-minute static measurements at six inches above the soil surface for the LACBWR open land area survey units.

The average background measurements ranged from approximately 4,000-6,000 counts per minute (cpm) in all the LACBWR Class 2 and Class 3 open land area survey units with the exception of Class 3 Survey Unit L3-012-109, Plant Access and ISFSI Haul Road Grounds, which had an average background measurement that ranged from approximately 5,000-12,000 cpm. The NRC staff believes the higher background measurement levels in Survey Unit L3-012-109 are mostly due to the adjacent Genoa 3 coal pile, and could also be influenced by the presence of asphalt and concrete road materials. Specifically, the staff noted that the scan areas that had higher background measurement values were Scan Area C and Scan Area D. As can be seen in Figure 4, reproduced from the FSS release record for Survey Unit L3-012-109 (ADAMS Accession No. ML20031C852), these areas are closer to the Genoa 3 coal pile than Scan Area A and Scan Area B in Survey Unit L3-012-109.

Figure 4. Survey Unit L3-012-109 Scan Area Locations Map (Reproduced from the LACBWR FSS Release Record for L3-012-109)

As part of the evaluation of background measurements for the LACBWR Class 2 and Class 3 open land areas, the NRC staff noted that ideally the measurements would be from a background reference area (not at six inches above the soil surface in the survey units to be scanned during FSS). However, the staff also noted that in most of the LACBWR open land area survey units, these background radiation measurements were low in comparison to the scan action levels and associated DCGLs. For the survey units adjacent to the Genoa 3 coal pile, which is a known naturally occurring radioactive material (NORM) source, a suitable reference area which properly estimated the background from that source would ideally have been identified. However, given that the survey units with slightly elevated background measurements are adjacent to a known NORM source, the way in which background radiation was measured is not a compliance issue for those survey areas. Therefore, the staff determined this method for defining background radiation is not safety significant and will not impact compliance with the unrestricted release criteria for the Class 2 or Class 3 open land areas.

In addition, the licensee did not subtract background radiation from the LACBWR soil samples that were submitted for detailed laboratory analyses, which is a conservative approach when determining the ROC concentration in these soil samples to determine compliance with the release criteria. Finally, the NRC staff noted that the average background radiation levels identified by the licensee for the LACBWR Class 2 and Class 3 open land areas are comparable to the levels measured by ORISE during confirmatory survey activities. Based on the above considerations, the NRC staff finds that the licensees methodology for background radiation determination in the LACBWR Class 2 and Class 3 open land area survey units, as demonstrated in the FSS release records for these survey units, is acceptable.

3.3.2.4 Investigation Samples and Scan Action Levels Section 5.5.2.6, Determining Investigation Levels, of MARSSIM provides the basis for determining FSS investigation levels to indicate when additional radiological investigations may be necessary as a result of survey scan outcomes. The FSS investigation levels for each class of survey unit are presented in Table 5-16, FSS Investigation Levels, of the LACBWR LTP, and are provided as Table 4 below. This table also corresponds to Table 5.8, Example Final Status Survey Investigation Levels, of MARSSIM, which provides example investigation levels.

Table 4. FSS Investigation Levels Classification Scan Investigation Levels Direct Investigation Levels

>Operational DCGL or >MDCscan if MDCscan Class 1 >Operational DCGL is greater than Operational DCGL

>Operational DCGL or >MDCscan if MDCscan Class 2 >Operational DCGL is greater than Operational DCGL

>Operational DCGL or >MDCscan if MDCscan Class 3 >0.5 Operational DCGL is greater than Operational DCGL Section 5.6.4.6, Investigation Process, of the LACBWR LTP states that survey areas where radioactivity is identified in excess of the given investigation levels will be addressed by further biased surveys and sampling as necessary according to the investigation levels in Table 5-16 of the LTP. For Class 1 and Class 2 survey areas, the soil sample direct investigation level is a survey result greater than the Operational DCGL. For Class 3 survey areas, the soil sample direct investigation level is a survey result greater than 50% of the Operational DCGL. The MARSSIM approach was also used to determine the soil sample direct investigation levels for the LACBWR site based on the soil Operational DCGL values. The soil sample direct

investigation levels used for the LACBWR Class 2 and Class 3 open land areas during the FSS are shown in Table 5 below. Based on consistency with the MARSSIM guidance, the NRC staff finds the licensees approach for investigation sampling acceptable.

Table 5. Soil Direct Investigation Levels for LACBWR Class 2 and Class 3 Survey Units Class 2 Class 3 Radionuclide of Concern Soil Investigation Level Soil Investigation Level (picocuries per gram (pCi/g)) (pCi/g)

Cs-137 17.31 8.655 Co-60 3.83 1.915 Eu-152 8.51 4.255 Eu-154 7.89 3.945 During the LACBWR FSS, the licensee applied an action level for surface scans of Class 2 and Class 3 open land survey units equal to the average background radiation level (in cpm) plus 50% of the soil Operational DCGL (i.e., 1,762 cpm). The NRC staff noted that according to Table 5-16 of the LACBWR LTP, the licensee could have used a scan investigation action level equal to the full Operational DCGL or the scan MDC, if the scan MDC was greater than the associated Operational DCGL. However, in this case the licensee used a more conservative scan action level by setting it to 50% of the Operational DCGL, which also created a more conservative scan MDC. This was especially true in survey areas where the background radiation was high, which would more readily drive the scan MDC to be larger than the 50% of the Operational DCGL that was used as the scan investigation action level.

In response to scan alarms during FSS of the LACBWR Class 2 and Class 3 open land survey areas, investigational soil samples were taken for analysis in accordance with the licensees investigation process. Scan alarms were recorded in two Class 2 and two Class 3 open land survey units. Investigational soil samples were taken by the licensee at these scan alarm locations unless a systematic sample representing the location had already been taken during FSS. Specifically, there were eleven scan alarms resulting in seven investigational soil samples in Class 2 open land survey units, and 47 scan alarms resulting in 32 investigational soil samples in Class 3 open land survey units. The NRC staff noted that the abundance of scan alarms in one of the Class 3 open land survey units (survey unit L3-012-109) was due to there being a higher background radiation contribution from the adjacent Genoa 3 coal pile, as discussed previously in Section 3.3.2.3 of this evaluation.

Based on the above considerations, the NRC staff finds that the licensees approach to scan action levels for the LACBWR Class 2 and Class 3 open land area survey units is adequate.

Although the licensee did not strictly follow the investigation action level criteria in Table 5-16 of the LACBWR LTP, the licensees approach was more conservative than specified in the LTP. In addition, the soil sample direct investigation levels are appropriate because, as demonstrated in the FSS release records for these survey units, the action levels are consistent with the applicable MARSSIM guidance and align with the associated discussion in Section 5.5.2.6 and Section 5.6.4.6 of the NRC-approved LACBWR LTP. Therefore, the investigation sampling and scan action levels for the Class 2 and Class 3 open land area survey units are acceptable.

3.3.2.5 Number of Samples and Sample Locations Section 5.6.4.1, Sample Size Determination, of the LACBWR LTP specifies the use of MARSSIM and Appendix A, Implementing the MARSSIM Approach for Conducting Final Radiological Surveys, of NUREG-1757, Volume 2, to determine the number of sampling and measurement locations (sample size - N) necessary to ensure sufficient data for statistical analysis, such that there is reasonable assurance that the survey unit will pass the requirements for release. Table 5.5, Values of N for Use with the Sign Test, of MARSSIM provides guidance on determining the minimum number of survey samples to be taken based on sign test results and Type I (release of a survey unit containing residual radioactivity above the release criterion, or false negative) and Type II (failure to release a survey unit when the residual radioactivity is below the release criterion, or false positive) decision error rates.

The NRC staff verified that the number of sampling and measurement locations collected from the LACBWR Class 2 and Class 3 open land areas was determined by establishing the acceptable Type I and Type II decision errors, calculating the relative shift, and using the sample size determination approach described in MARSSIM. Specifically, the LACBWR LTP committed to using a Type I and Type II decision error of 5% and applying the sign test. The sample size from Table 5.5 of MARSSIM that equates to a Type I and Type II decision of 5% for use with the sign test is an N value of fourteen samples. Therefore, the staff confirmed that the licensee intended to collect at least fourteen static systematic measurements for the Class 2 and Class 3 open land areas. In addition, the licensee applied a relative shift of three for all the open land survey units because the calculated value of the relative shift was larger than three.

The NRC staff also verified that for the LACBWR Class 2 and Class 3 open land areas, the number of systematic and judgmental samples actually taken in each survey unit met or exceeded the number prescribed. All the LACBWR open land area survey units required the collection of at least fourteen systematic soil samples, except Class 3 Survey Unit L3-012-102, Transmission Switch Yard, which required the collection of seventeen systematic samples. For the Class 2 open land survey units, measurement locations were based on a systematic grid with a random starting point. For the Class 3 open land survey units, systematic soil sample measurement locations were based on simple random locations. The Visual Sample Plan (VSP) software tool was used by the licensee to determine the soil sample locations for the LACBWR survey units, as described in TSD LC-FS-PR-002, Final Status Survey Package Development.

Specifically, VSP was used to determine the systematic sample location grids for the Class 2 survey units, as well as the random sample locations of the fourteen static measurements for the Class 3 survey units. The VSP systematic measurements are intended to be unbiased, and ensure the measurements are independent and support the assumptions of the statistical tests.

Based on the above considerations, the NRC staff finds that the licensees approach to determining the number of samples and sample locations for the LACBWR Class 2 and Class 3 open land area survey units, as demonstrated in the FSS release records for these survey units, is consistent with the applicable MARSSIM and NUREG-1757 guidance and aligns with the associated discussion in the NRC-approved LACBWR LTP. Therefore, the sampling methodology for the LACBWR Class 2 and Class 3 open land area survey units is acceptable.

3.3.2.6 Verification of HTD Radionuclides (Sr-90)

Section 5.1, Radionuclides of Concern and Mixture Fractions, of the LACBWR LTP specifies the process that will be utilized to sample for HTD radionuclides during FSS and includes analyzing at least 10% of the FSS samples from open land survey units for the presence of

Sr-90, as well as conducting an HTD radionuclide analysis for any sample resulting in a SOF greater than 10% of the Operational DCGL. The NRC staff verified that the number of HTD radionuclide samples taken in each Class 2 and Class 3 open land survey unit met or exceeded the number of samples required in the LACBWR LTP.

Specifically, each LACBWR Class 2 and Class 3 open land survey unit provided at least one HTD radionuclide measurement sample. There were nine HTD radionuclide samples taken in Class 2 open land survey units and nine HTD radionuclide samples taken in Class 3 open land survey units. None of the HTD radionuclide analyses detected Sr-90 above the MDC. In addition, laboratory gamma spectroscopy results indicated that no systematic or judgmental soil samples exceeded a SOF of 10% of the Operational DCGL with the exception of one systematic sample with a SOF of 0.11 in Class 3 Survey Unit L3-012-109, primarily due to the presence Eu-152 in the soil sample. A total of five samples from this survey unit were analyzed for HTD radionuclides to establish that Eu-152 was the primary HTD radionuclide in the survey unit.

Based on the above considerations, the NRC staff finds that the licensees methodology for assessing the HTD radionuclides in the LACBWR Class 2 and Class 3 open land area survey units, as demonstrated in the FSS release records for these survey units, is consistent with the associated discussion in the NRC-approved LACBWR LTP. Therefore, the verification of HTD radionuclides for the LACBWR Class 2 and Class 3 open land area survey units is acceptable.

3.3.2.7 Quality Control Measurements Section 5.9, Quality Assurance, of the LACBWR LTP states that the quality assurance (QA) program complies with the requirements set forth in Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants, of 10 CFR Part 50; Subpart H, Quality Assurance, of 10 CFR Part 71, Packaging and Transportation of Radioactive Material; and Subpart G, Quality Assurance, of 10 CFR Part 72. This section of the LTP also states that one randomly selected split sample will be chosen for QC analysis from each LACBWR survey unit.

The NRC staff verified that the number of QC samples taken in each Class 2 and Class 3 open land survey unit met or exceeded the number required for field split and duplicate analyses.

Specifically, each LACBWR Class 2 and Class 3 open land survey unit provided at least two QC measurement samples. There were fifteen QC samples taken in Class 2 open land survey units and ten QC samples taken in Class 3 open land survey units. Laboratory gamma spectroscopy results indicated that Cs-137 was detected above the MDC in four Class 2 open land survey units. The maximum Cs-137 concentration measured in these Class 2 open land area QC split samples was 0.097 pCi/g. No other ROCs were detected above the MDC. There were no QC split samples with ROCs above the MDC in the Class 3 open land area survey units.

In the licensees QC sample analysis for two Class 2 and two Class 3 LACBWR open land survey units, potassium-40 (K-40) was substituted for the QC assessment since Cs-137 was not identified in the standard or comparison split sample above the MDC. In general, the NRC staff notes that K-40 should not be considered a substitute for QC assessment of Cs-137. The predominant gamma energy associated with Cs-137 is 662 kiloelectronvolt (KeV), and the gamma energy for K-40 is 1,460 KeV. These gamma energies are too far apart for K-40 to be a suitable substitute for Cs-137 during a QC assessment. However, K-40 may be acceptable for use as part of a QC assessment for Cs-137 in situations where only low, slightly above MDC Cs-137 levels are present in the standard or comparison samples. Specifically, if Cs-137 was detected in both the standard and comparison sample, but only slightly above the MDC, there would not be a high level of confidence in those QC results. In these cases, K-40 was used by

the licensee for the QC assessment of Cs-137 because it is easily detectable and identifiable in most environmental media, including soil, and can be used to increase the confidence level in the QC results. Based on this limited use of K-40 in the QC sample analyses for four LACBWR open land survey units, the NRC staff finds this QC assessment approach acceptable.

Based on the above considerations, the NRC staff finds that the licensees methodology for assessing QC measurement samples in the LACBWR Class 2 and Class 3 open land area survey units, as demonstrated in the FSS release records for these survey units, is consistent with the associated discussion in the NRC-approved LACBWR LTP. Therefore, the QC approach for the LACBWR Class 2 and Class 3 open land area survey units is acceptable.

3.3.2.8 LACBWR Trench Excavation After FSS In May 2021, the licensee performed additional excavation work at the LACBWR site to create a trench for installation of fiber optic cable and a fire suppression line in support of ongoing activities at LACBWR and the Genoa 3 coal plant. The excavation spanned through five open land survey units: L3-012-109, L2-011-101, Area North of LSE Fence, L2-011-103, Genoa 3 Crib House Surrounding Area, L1-010-107, Outside East LSE Area, and primarily L1-010-104, North LSE Grounds. The excavation was approximately 500 feet (152 meters) in length and an average of approximately 10 feet (3 meters) wide. In accordance with the LACBWR LTP, creation of this trench required the licensee to perform additional survey activities to confirm the previously completed FSS of these open land areas was not impacted.

On May 6, 2021, and May 19, 2021, a radiological assessment and remedial action support survey was performed along the length of the trench, including a gamma walkover survey and the collection of judgmental soil samples. The survey plan was captured in LACBWR Sample Plan No. L1-010-104 RA (B), which divided the entire length of the trench into twelve segments for the survey. For the Ludlum 44-10 survey meter used, the average background radiation (measured from five 1-minute counts taken at a height of six inches from the surface of the survey units) was 4,006 cpm, resulting in a scan MDC of 4,684 cpm. The scan alarm setpoint for the trench was established as the average background radiation plus 50% of the Operational DCGL for soil (4,006 cpm + 1,762 cpm = 5,768 cpm). In addition, the scan MDC for Cs-137 at three inches from the soil surface was calculated as 3.7 pCi/g. The maximum gamma scan readings taken in each of the twelve survey segments of the trench were below this scan alarm setpoint, and the highest recorded scan reading in any segment was 5,070 cpm.

Nineteen judgmental soil samples were collected along the trench excavation and sent offsite to GEL Laboratories for analysis. ROC analyses were performed for Cs-137, Co-60, Eu-152, Eu-154, europium-155 (Eu-155), and niobium-94 (Nb-94); the results of the laboratory analyses were provided by GEL Laboratories on May 27, 2021. The maximum analytical result for Cs-137 in soil was 0.60 pCi/g, which is well below the Cs-137 Operational DCGL (17.31 pCi/g) for Class 2 and Class 3 open land survey units. All other analyzed ROCs were less than their respective MDCs. No confirmatory measurements were performed on the trench excavation by either ORISE or the NRC staff. However, the scan survey data and soil sample analytical results demonstrate that the Class 2 and Class 3 open land survey units impacted by the trench excavation still meet the criteria for unrestricted release, as described in the associated FSS release records. Therefore, the NRC staff finds the licensees approach for evaluation of the impact of the LACBWR trench excavation on the Class 2 and Class 3 open land areas that had previously completed FSS activities to be acceptable.

3.3.2.9 Conclusion for Class 2 and Class 3 Open Land Survey Areas The NRCs dose criteria for unrestricted site release are stated in 10 CFR 20.1402:

A site will be considered acceptable for unrestricted use if the residual radioactivity that is distinguishable from background radiation results in a [total effective dose equivalent] TEDE to an average member of the critical group that does not exceed 25 mrem (0.25 millisieverts) per year, including that from groundwater sources of drinking water, and that the residual radioactivity has been reduced to levels that are as reasonably achievable (ALARA).

Determination of the levels which are ALARA must take into account consideration of any detriments, such as deaths from transportation accidents, expected to potentially result from decontamination and waste disposal.

For the reasons discussed in the NRC evaluation of the LACBWR Class 2 and Class 3 open land area survey units, the NRC staff has reasonable assurance that the FSS release records for these survey units demonstrate that the residual radioactivity in the associated open land areas complies with the unrestricted release criteria. Specifically, the ORISE confirmatory soil concentrations for ROCs in all the LACBWR Class 2 and Class 3 open land area survey units were less than 50% of the associated Operational DCGLs. The maximum SOF for all Class 2 open land survey units was 0.010. The maximum SOF for all Class 3 open land survey units was 0.021. The ORISE confirmatory SOF results are generally lower than the LACBWR FSS SOF results. Given these considerations, the NRC staff concludes that the release of the LACBWR Class 2 and Class 3 open land area survey units will have no adverse impact on the ability of the site to meet the 10 CFR Part 20, Subpart E criteria for unrestricted release.

3.4 Class 1, Class 2, and Class 3 Buried Piping 3.4.1 Description of Survey Units Table 6 summarizes the LACBWR buried piping survey units, all of which were part of Phase 2 of the FSSR. Note that there was only one Class 1 buried piping survey unit (S1-011-102, Circulating Water Discharge Pipe), which was included in this evaluation in order to allow for the release of all of the LACBWR buried piping survey units as part of this action.

Table 6. Buried Piping Survey Units Survey Unit Type Survey Unit Description Phase Class S1-011-102 Buried Piping Circulating Water Discharge Piping 2 1 S2-011-103 A Buried Piping De-Icing Line 2 2 S2-011-103 B Buried Piping Low-Pressure Service Water Piping 2 2 S2-011-103 Buried Piping Circulating Water Intake Pipe 2 2 S3-012-109 A Buried Piping Storm Drain 1 2 3 S3-012-109 B Buried Piping Storm Drain 2 2 3 S2-011-101 A Buried Piping Storm Drain 3 2 2 S2-011-101 B Buried Piping Storm Drain 6 2 2 S3-012-102 A Buried Piping Storm Drain 4 2 3 S3-012-102 B Buried Piping Storm Drain 5 2 3

Survey Unit S1-011-102, Circulating Water Discharge Pipe Survey Unit S1-011-102 is an impacted Class 1 buried pipe survey unit, which consists of the interior surface of the LACBWR Circulating Water Discharge (CWD) Pipe. The steel pipe has an internal diameter of 60 inches and a total length of 421 feet, and runs from the LACBWR Turbine Building to a combined discharge structure on the banks of the Mississippi River. The interior surface area of the CWD Pipe is approximately 614.37 m2. The licensees survey plan called for collection of one sample measurement for every linear foot traversed through the pipe, for a total of at least 421 distinct measurements over the entire accessible pathway of the piping system. In addition, during survey design 89 systematic static measurements (approximately four for every twenty feet of piping) were added to assess the sides and top of the pipe, for a total of 510 static measurements that make up the systematic measurement population.

Survey Unit S2-011-103 A, De-Icing Line Survey Unit S2-011-103 A is a Class 2 buried pipe survey unit, which consists of the interior surface of the LACBWR De-Icing Line, an eighteen inch () interior diameter steel pipe that runs approximately 105 feet from the LACBWR Crib House to the Turbine Building. The total interior surface area of the De-Icing Line is approximately 46 m2. The licensees survey plan selected 50% survey coverage for this buried piping survey unit. Therefore, one sample measurement was collected for every two linear feet traversed through the pipe, for a total of at least 50 distinct measurements over the entire accessible pathway of the piping system.

Survey Unit S2-011-103 B, Low-Pressure Service Water Piping Survey Unit S2-011-103 B is a Class 2 buried pipe survey unit, which consists of the interior surface of the LACBWR Low-Pressure Service Water (LPSW) Pipe, a sixteen inch interior diameter steel pipe that runs approximately 44 feet. The total interior surface area of the LPSW Pipe is approximately 17 m2. The licensees survey plan selected 50% survey coverage for this buried piping survey unit. Therefore, one sample measurement was collected for every two linear feet traversed through the pipe, for a total of at least 23 distinct measurements over the entire accessible pathway of the piping system.

Survey Unit S2-011-103, Circulating Water Intake Pipe Survey Unit S2-011-103 is a Class 2 buried pipe survey unit, which consists of the interior surface of the Circulating Water Intake (CWI) Pipe, two 42 interior diameter steel pipes that merge into a 60 interior diameter steel pipe that runs approximately 46.5 feet from the LACBWR Crib House to the Turbine Building. The total interior surface area of the CWI Pipe is approximately 57 m2. The licensees survey plan selected 50% survey coverage for this buried piping survey unit. Therefore, a total of at least 24 distinct measurements over the entire accessible pathway of the piping system were required. In addition, during survey design five systematic static measurements were added, for a total of 29 static measurements that make up the systematic measurement population.

Survey Unit S3-012-109 A, Storm Drain 1 Survey Unit S3-012-109 A is a Class 3 buried pipe survey unit, which consists of a ten inch interior diameter polyvinyl chloride (PVC) pipe that is used to direct storm water out of the roadway south of the LACBWR Back-up Control Center (BCC) building. The total length of the pipe is approximately 195 feet, and the total interior surface area is 47.4 m2. The licensees

survey plan selected 10% survey coverage for this buried piping survey unit. Therefore, a total of twenty measurements over the entire accessible pathway of the piping system were taken.

Survey Unit S3-012-109 B, Storm Drain 2 Survey Unit S3-012-109 B is a Class 3 buried pipe survey unit, which consists of a 48 interior diameter concrete pipe that runs approximately 624 feet from a culvert east of the BCC building westward, where it discharges into the Mississippi River. The total interior surface area is 729 m2. The licensees survey plan selected 10% survey coverage for this buried piping survey unit. Therefore, one measurement was to be collected for every ten linear feet traversed through the pipe, for a total of at least 62 distinct measurements over the entire accessible pathway of the piping system. However, the last twenty feet was inaccessible due to sediment and river levels, which resulted in a systematic population of 60 distinct sample measurements.

Survey Unit S2-011-101 A, Storm Drain 3 Survey Unit S2-011-101 A is a Class 2 buried pipe survey unit, which consists of a ten inch interior diameter PVC pipe that resides to the east of the LACBWR Administration Building. The total length of the pipe is approximately 104.5 feet, and the total interior surface area is 26 m2.

The minimum survey coverage for a Class 2 FSS unit is 10%; however, the licensees survey plan selected 33% survey coverage for this buried piping survey unit. Therefore, a total of 33 distinct measurements over the entire accessible pathway of the piping system were taken.

Survey Unit S2-011-101 B, Storm Drain 6 Survey Unit S2-011-101 B is a Class 2 buried pipe survey unit, which consists of a ten inch interior diameter PVC pipe that runs approximately 84 feet. This storm drain system collected water from the roadway east of the LACBWR Administration Building and ran north, where it connected to a 48 interior diameter concrete storm drain (Storm Drain 2) that leads to the Mississippi River. The total interior surface area is 20.42 m2. The licensees survey plan selected 25% survey coverage for this buried piping survey unit. Therefore, one measurement was collected for every four linear feet traversed through the pipe, for a total of at least 21 distinct measurements over the entire accessible pathway of the piping system.

Survey Unit S3-012-102 A, Storm Drain 4 Survey Unit S3-012-102A is a Class 3 buried pipe survey unit, which consists of a twelve inch interior diameter clay pipe that resides to the north of the LACBWR Switchyard. The total length of the pipe is approximately 330 feet, and the interior surface area is 96.31 m2. The licensees survey plan selected 10% survey coverage for this buried piping survey unit. Therefore, a total of 33 distinct measurements over the entire accessible pathway of the pipe system were taken.

Survey Unit S3-012-102 B, Storm Drain 5 Survey Unit S3-012-102B is a Class 3 buried pipe survey unit, which consists of a 30 interior diameter vitrified clay pipe that runs east-west underneath the northern portion of the LACBWR Switchyard. The total length of the pipe is approximately 400 feet, and the total interior surface area is 291.86 m2. The licensees survey plan selected 10% survey coverage for this buried piping survey unit. Therefore, a total of 40 distinct measurements over the entire accessible pathway of the piping system were taken.

3.4.2 NRC Evaluation of the Buried Piping Survey Areas The licensees overall method for collecting survey samples and determining the residual radioactivity in the LACBWR buried piping survey units is as follows. The licensee collected static sample measurements representing the gamma activity in gross cpm for each specific measurement location within the survey area. The licensee subtracted a background radiation value, and then converted the value to disintegrations per minute (dpm) using an efficiency factor based on the calibration source and the efficiency correction factors detailed in LACBWR TSD LC-FS-TSD-005, MCNP Modeling of Water Discharge Pipes for the La Crosse Boiling Water Reactor (ADAMS Accession No. ML20352A269). The total activity in dpm was then adjusted for the assumed effective surface area commensurate with the pipe diameter, resulting in units of dpm per 100 centimeters squared (cm2), or dpm/100 cm2.

From there, the total gamma surface activity for each sample measurement was converted to an activity concentration for the individual gamma-emitting ROCs, based on the normalized gamma mixture from Table 4-1, Dose Significant Radionuclides and Mixture for Buried Pipe, of each FSS release record for the LACBWR buries piping survey units. The licensee then inferred concentrations for Sr-90 using the surrogate ratio approach in accordance with Chapter 5, Final Status Survey Plan, of the LACBWR LTP. The resulting values in dpm/100 cm2 were then compared to the buried piping DCGLs to determine compliance with the release criteria.

The NRC staff verified that the results of the LACBWR FSS demonstrate that the buried piping survey units meet the radiological criteria for license termination, and may therefore be released from the LACBWR 10 CFR Part 50 license. Specifically, the NRC staff reviewed the adequacy of the survey methods and instrumentation, the sufficiency of the number of samples collected, the quality control program, the comparison of the results to the release criteria, and the results of the statistical tests to demonstrate compliance. A discussion of specific topics that received an in-depth review during the NRC staffs evaluation are presented below.

3.4.2.1 Number of Samples, Sample Location, and Sample Coverage The approved survey plan in the LACBWR LTP for the buried piping survey areas consisted of static measurements acquired at a pre-determined interval to achieve the desired areal coverage. The static measurement output represents the gamma activity in gross cpm for each foot of piping traversed. Since areal coverage is achieved using the area of detection for each static measurement collected, scanning is not applicable to the survey of pipe internal surfaces.

The number of static measurements necessary for each survey unit is determined by dividing the length of the pipe into equal one-foot intervals and planning to collect a measurement at regular intervals in order to achieve the required coverage. For example, for a 100 foot long pipe, 50 measurements would be taken (one at every two feet) to achieve 50% survey coverage. The NRC staff verified that the number of static measurements collected within each buried piping survey unit was adequate to meet the survey coverage requirements.

However, the NRC staff noted that LACBWR Storm Drain 3, Storm Drain 6, and Storm Drain 2 were impacted by an inadvertent release of radioactively contaminated water that occurred on the site from February 22-23, 2017, which had the potential to affect the initial survey coverage and planning assumptions for these survey units. The licensee had been using the Turbine Building East Baker Water Storage Tank near the LACBWR Turbine Building as the temporary holding tank for radiologically contaminated liquid waste prior to discharge to the Mississippi River through a filtration system. In late February 2017, the licensee noted that the containment berm, north of the storage tank, was full and spilling over the berm. The water that spilled over

the berm pooled and then drained into a Radiological Controlled Area (RCA) storm sewer drain (Storm Drain 3, which flows into Storm Drain 6 and then Storm Drain 2).

The licensee determined that a sump pump hose that had been left in the Turbine Building East Baker Water Storage Tank overnight was siphoning into the containment berm. Approximately 400 gallons of contaminated water had been siphoned from the tank over about sixteen hours.

The water topped off the berm and spilled onto an asphalt surface, traveling approximately 30 feet into the storm sewer. The contaminated water then traveled through the sewer system to the Mississippi River. Results from water samples and smear surveys after the event revealed Cs-137 in concentrations ranging from 1.1 picocuries per milliliter (pCi/ml) to 2.86 pCi/ml.

The concentration of the release did exceed the 10 CFR Part 20, Appendix B, limit of one pCi/ml but did not exceed the NRC reportability threshold of greater than twenty times the 10 CFR Part 20, Appendix B, limit, as stated in 10 CFR 50.73(a)(2)(viii)(B). However, the licensee reported the release to the Wisconsin Department of Natural Resources, and subsequently to the NRC in Event Report No. 52575, in accordance with 10 CFR 50.72(b)(2)(xi). The event is also tracked in the Nuclear Material Events Database (NMED) as Item No. 170122. As a result of this release, the NRC issued the licensee one Severity Level IV, Non-Cited Violation (SL IV NCV) of 10 CFR 50.54(a)(1), which was a self-revealed violation associated with the sites failure to appropriately implement the quality assurance program. The Turbine Building East Baker Water Storage Tank release event is summarized in this evaluation because information from it is used to inform the review of the FSS release records for Storm Drain 3, Storm Drain 6, and Storm Drain 2, and the event was not summarized in the release records.

The NRC staff noted that Storm Drain 3 and Storm Drain 6 were classified as Class 2 survey units with survey coverage of 33% and 25%, respectively. Given that the static measurements collected in these two survey units were not close to exceeding the Base Case DCGL, Class 2 remains an appropriate classification, even considering the tank release event in 2017.

LACBWR Storm Drain 2 was classified as a Class 3 survey unit and received survey coverage of 9.62%. The licensee intended to cover 10% of the pipe during the survey, but the last 20 feet contained too much sediment and water from the river to receive static measurements. The licensee also collected three sediment samples from Storm Drain 2 during FSS and only Cs-137 was present, at a maximum concentration of approximately 0.05 pCi/g. The licensee clarified to the NRC that they did not reclassify Storm Drain 2 from Class 3 to Class 2 after the tank release event because the measured values from the samples taken following the event indicated that the residual radioactivity would still be a small fraction of the approved Base Case DCGL.

The NRC staff also noted that although Storm Drain 2 was documented as Class 3 in the associated FSS release record, this storm drain received similar survey coverage as the minimum requirements in MARSSIM for Class 2 survey units. In addition, the net results from the static measurements in dpm/100 cm2 were a fraction of the Base Case DCGL, ranging from 5% to 8%. Therefore, because LACBWR Storm Drain 2 was sampled with a similar survey coverage as required by MARSSIM for Class 2 survey units, and the measured results were a fraction of the Base Case DCGL, the staff finds that this survey unit was surveyed adequately.

3.4.2.2 Detector Efficiency In the August 19, 2020, RAIs associated with the LACBWR FSSR review, the NRC asked the licensee to explain the method that was used to determine the detector efficiencies for various sized buried piping. In the November 2, 2020, RAI response, the licensee described a method

for determining the efficiency of the radiation detector using a flexible Cs-137 source that was 30.48 centimeters (cm) by 100 cm (approximately 3050 cm2). After the detector was placed in a pipe survey jig that would allow it to traverse through the pipe, the detector was moved over the Cs-137 source at intervals and one-minute static measurements were collected. Seven intervals were averaged, then background radiation was subtracted, and the result in cpm was divided by the activity of the source to determine the detector efficiency. The licensee determined the background radiation range for the efficiency factor by taking a ten-minute static count while the detector was in the pipe survey jig inside the pipe. A control of +/- 20% of the ten-minute static count cpm value was then placed on the pre and post background checks for the detector.

The licensee calculated the effective detection area using the inner diameter of each pipe to determine the circumference and multiplied it by the one foot length of pipe that each measurement was covering. Therefore, the effective area is directly proportional to the diameter of the pipe. The calculated effective detection areas for various pipe diameters and lengths are summarized in Table 7 below. The NRC staff verified the licensees calculations for the effective area of each pipe. The staff noted that for the CWI Pipe, there are two different effective areas of detection because there are two pipe size diameters. The licensee applied the same area of detection (that associated with the 60 diameter piping) for all measurements. The effective area of detection for the 42 diameter sections of the CWI Pipe would be smaller (10,215 cm2).

Dividing by a larger area of detection gives a smaller dpm/100 cm2 activity value, so applying the 60 diameter area of detection to the smaller piping size is non-conservative. However, the NRC staff evaluated the resulting measurements for the CWI Pipe and verified that they were still below the Operational DCGL when using the smaller (42 diameter) area of detection.

Table 7. Source Areas (cm2) for Various Pipe Diameters and Lengths (Table 2 and Table 4 of LACBWR TSD LC-FS-TSD-005)

Pipe Diameter Pipe Length (feet) 60 48 30 18 12 10 1 14593 11675 7297 4378 2919 2432 2 29186 23349 14593 8756 5837 4864 3 43780 35024 21890 13134 8756 7297 5 72966 58373 36483 21890 14593 12161 10 145932 116745 72966 43780 29186 24322 20 291864 233491 145932 87559 58373 48644 30 437795 350236 218898 131339 87559 72966 The actual measurement conditions in the LACBWR buried piping survey units were different from the conditions present during calibration of the radiation detector. Specifically, the detector was calibrated using a National Institute of Standards and Technology (NIST)-traceable calibration source with an area of 3050 cm2 source, while assuming the contamination in the pipe is uniformly distributed along the entire pipe circumference. Given the difference in actual survey measurement conditions versus calibration conditions, the licensee determined detector efficiency correction factors to account for the difference in conditions in the buried piping.

The licensee used Monte Carlo N-Particle (MCNP) code calculations to model the interactions of photons with a radiation detector in a uniformly contaminated pipe for various diameters and lengths of piping, as well as modeling the response of the detector from a 3050 cm2 calibration

source. For each pipe geometry, the licensee then calculated a radiation detector efficiency correction factor, which is a ratio of (1) the MCNP-modeled response of the detector to a uniformly contaminated source to (2) the MCNP-modeled response of the detector to the 3050 cm2 calibration source. This correction factor was then multiplied by the measured efficiency of the radiation detector, determined by utilizing the NIST-traceable planar calibration source in the field, in order to more closely account for actual survey measurement conditions.

The NRC staff reviewed LACBWR TSD LC-FS-TSD-005 and TSD LC-FS-TSD-003, Assessment of the LACBWR Circulating Water Discharge Pipe Final Status Survey Data for Detection Efficiency and Detector Background (ADAMS Accession No. ML20352A272), which contain the details of the calculations for the radiation detector efficiency correction factors that the licensee used. Table 8 below summarizes the efficiency correction factors and the background values the licensee calculated for each size pipe of various materials. Note that the licensee used the efficiency correction factors associated with a one-foot source length for each pipe diameter because each survey measurement represents one foot of length. Also note that the efficiency correction factors are larger than one when the surface area of the pipe is larger than the surface area of the 3050 cm2 calibration source. This is because the MCNP correction factor ratio also accounts for the change in surface area, which is described further below.

Table 8. Efficiency Correction Factors for Buried Piping Pipe Source Length (feet) and Efficiency Correction Factor Pipe Diameter Material (inches) 1 2 3 5 10 20 30 60 Steel (CWD) 1.311 2.174 2.680 3.387 4.185 4.725 5.062 60 Steel (CWI) 1.311 2.174 2.680 3.387 4.185 4.725 5.062 48 Concrete 1.349 2.247 2.845 3.564 4.423 4.881 5.176 30 Concrete 1.362 2.203 2.736 3.431 3.922 4.379 4.414 18 Steel 1.368 2.159 2.620 3.016 3.404 3.588 3.580 12 Clay 1.000 1.385 1.569 1.770 1.860 1.898 1.949 10 PVC 0.798 1.116 1.225 1.355 1.418 1.424 1.465 The NRC staff noted that during the ORISE confirmatory survey of several of the LACBWR CWD Pipe, ORISE used a radiation detector efficiency that was measured using a calibration source in the field with an area of 3,315 cm2 and a smaller source area modification factor, whereas the licensee applied a higher detector efficiency through their use of correction factors and a larger source area modification factor when conducting surface area conversions for the various pipes. The issue in the licensees approach is that the efficiency correction factor adjusted for the different pipe surface area sizes, and then the surface area conversion again converted to a larger area size. In this sense, the licensee was double counting for the area adjustments. It is not inherently incorrect to multiply by an efficiency correction factor using a ratio of MCNP model run results, but the efficiency correction factor should be decoupled from the adjustment in geometry size in order for the licensees additional surface area conversion calculations to be correct. Table 9 below summarizes key assumptions in the ORISE confirmatory survey of the CWD Pipe versus the assumptions in the FSS of the CWD Pipe.

Table 9. Comparison of Efficiencies for the CWD Pipe Confirmatory Survey and FSS ORISE Confirmatory Licensee FSS Parameter Survey of the CWD Pipe of the CWD Pipe Detector Ludlum 44-10 Ludlum 44-10 Calibration Source Cs-137 Cs-137 Area of Calibration Source 3315 cm2 3050 cm2 3315 cm2 (same area as 14590 cm2 (surface area of a Effective Area of Detector calibration source) one foot length of a 60 pipe)

Efficiency Calculated 3.37E-03 2.99E-03 During Calibration Efficiency Correction Factor None (1) 1.311 Corrected Efficiency 3.37E-03 3.799E-03 (1.311*2.99E-03)

Source Area 3,315/100 (33.15 cm2) 14590/100 (145.9 cm2)

Modification Factor Equivalent Gross (5000)/(3.37E-03*33.15) = (5000)/(3.799E-03*145.9) =

dpm/100 cm2 for 5000 cpm 44,757 dpm/100 cm2 9,021 dpm/100 cm2 Background cpm 3,322 cpm 3,258 cpm Equivalent Net (5000-3322)/(33.15*3.37E- (5000-3258)/(145.9*3.79E-03) dpm/100 cm2 for 5000 cpm 03) = 15,020 dpm/100 cm2 = 3,143 dpm/100 cm2 The NRC staff determined that the licensees overall approach to using a radiation detector efficiency correction factor was acceptable, given that the calibration source had a different geometry than the source term expected in the buried piping. However, in the subsequent efficiency calculations, the staff notes that the licensee should have used the source area modification factor associated with the calibration source area since the licensees calculations already accounted for the pipe surface area modification through the efficiency correction factor.

Alternatively, the licensee should have decoupled the source area modification factor from the efficiency correction factor, which would have resulted in correction factors that would be less than one for the larger pipes, before using the source area modification factor for various sized piping. Because of this inaccuracy, the NRC staff performed confirmatory calculations using the licensees buried piping survey data and the correct source area modification factor adjustments. Based on this analysis with the corrected information, the staff confirmed that the LACBWR buried piping survey results continue to demonstrate compliance with the associated Operational DCGLs from the approved LACBWR LTP.

3.4.2.3 Background Radiation Measurements Section 5.7.1.8, Buried Piping, of the LACBWR LTP discusses buried piping surveys and describes the FSS activities that were planned for the buried piping. The NRC staff note that this section of the LACBWR LTP, does not discuss subtracting background from the piping measurements. Specifically, Section 5.7.1.8 of the LACBWR LTP stated, in part:

A static measurement is acquired at a pre-determined interval for the areal coverage to be achieved. The measurement output represents the gamma activity in gross cpm for each foot of piping traversed. This measurement value in cpm is then converted to dpm using the efficiency of the detector. The total activity in dpm is then converted to activity per unit area commensurate with the pipe diameter, resulting in measurement results in units of dpm/100 cm2. A surrogate correction based upon the radionuclide distribution present in the pipe

is then applied to the gamma emission to account for the presence of other non-gamma-emitting radionuclides in the mixture. During data assessment, the measurement results are compared to the buried pipe Operational DCGLs.

As part of the August 19, 2020, RAIs associated with the LACBWR FSSR review, the NRC staff requested information on the locations where the background radiation measurements were acquired for the buried piping survey units, as well as the rationale for why the locations were a suitable reference area. In the November 2, 2020, RAI response, the licensee discussed that the original background radiation values that were intended to be used for buried piping were measured in the LACBWR North Yard area and were relatively high compared to the actual activity measurements in several of the piping survey units. The licensee attributed the higher background radiation readings to the higher terrestrial background that would exist above ground due to fallout, as well as the nearby operating coal plant. Specifically, the licensee noted that the coal ash pile contains naturally occurring radioactive material that would increase background radiation levels above ground relative to those underground where the buried pipes were located. Therefore, the licensee conducted a background study using various sized clean pipes and attempting to mimic a buried pipe. During this study, the licensee measured background radiation by placing clean piping on a concrete pad surrounded with concrete barriers to reduce terrestrial background. Clean fill was placed on the concrete pad with the pipes, and clean fill was then placed on top of the pipes to try to mimic a buried pipe.

The NRC staff reviewed TSD LC-FS-TSD-003, which was provided with the licensees RAI response and developed specifically to address two issues associated with the FSS of the CWD Pipe, but was also applied more generically to address the radiation detector efficiency for other piping survey units. The staff note that this document does not contain the background radiation values used for piping survey units other than the CWD Pipe. However, a brief description of the background study and background radiation values used for each size pipe was provided in all of the LACBWR buried piping survey unit FSS release records. Table 10 below summarizes the background radiation values that were determined during the LACBWR background study and used for each of the buried piping survey units. Note that the background study radiation measurements for the CWI Pipe were determined to still be too high by the licensee, due to the length of the pipe being too short compared to its large diameter, which allowed terrestrial background radiation to influence the background study measurements. Therefore, the licensee decided that background would not be subtracted from any measurement in the CWI Pipe.

Given that the LACBWR LTP did not discuss subtracting background radiation from the buried piping survey measurements, and since the background reference values proved somewhat difficult to establish by the licensee, the NRC staff evaluated the associated FSS data and determined that even without subtracting background radiation values, while also correcting for the source area modification factor as discussed above, five out of the nine of the LACBWR buried piping survey units would have still passed the statistical sign test, which compares the survey results to the Operational DCGL. The four buried piping survey units that would not have passed the sign test without subtracting background radiation are Storm Drain 1, Storm Drain 2, Storm Drain 4, and Storm Drain 5. These survey units are discussed in more detail below.

The NRC staff notes that the purpose of this independent exercise was to help inform the importance of the selection of background radiation reference values and the influence of background radiation values in passing the statistical test. It should not be interpreted as indicating that it was inappropriate for the licensee to subtract background radiation from the gross survey readings to determine a measurement that would be compared to the DCGLs.

Section 8.2.3, Select the Tests, of MARSSIM states the following about selecting a test:

The one-sample statistical test (sign test) described in Section 5.5.2.3, Contaminant Not Present in BackgroundDetermining Numbers of Data Points for Statistical Tests, should only be used if the contaminant is not present in background and radionuclide-specific measurements are made. The one-sample test may also be used if the contaminant is present at such a small fraction of the DCGLW value as to be considered insignificant. In this case, background concentrations of the radionuclide are included with the residual radioactivity (i.e., the entire amount is attributed to facility operations). Thus, the total concentration of the radionuclide is compared to the release criterion. This option should only be used if one expects that ignoring the background concentration will not affect the outcome of the statistical tests. The advantage of ignoring a small background contribution is that no reference area is needed. This can simplify the final status survey considerably.

As discussed in this excerpt, MARSSIM intends that one-sample tests (e.g., the sign test) are applicable if radionuclide-specific measurements are made to determine the concentration(s) of the radionuclide(s) and the contaminant is not present in the background. If the contaminant is present in the background the sign test may be used, but in this case the background radiation is ignored (i.e., not subtracted before comparing the total concentration of the radionuclide to the release criteria). Section 8.4, Contaminant Present in Background, of MARSSIM provides guidance on using the Wilcoxon Rank Sum (WRS) test (also called the Mann-Whitney test) to compare radiation measurements from the reference area and survey unit when the contaminant is present in the background. In the case of the LACBWR buried piping survey units, the piping measurements were not radionuclide-specific, and background radiation contributes to the gross activity measurements even though the radionuclide of interest may not appear in the background. Therefore, the NRC staff notes that the WRS test would be the recommended statistical test used for comparison of the survey measurements to the release criteria, especially if background radiation is subtracted from the gross activity measurements.

Table 10. Piping Efficiencies and Background Values Area of Pipe Pipe Detector Background Survey Unit Survey Unit Detection Size Material Efficiency1 Value (cpm)

(cm2)

S1-11-102 60 Steel CWD Piping 0.003799 14590 3258 S2-011-103 A 18 Steel De-Icing Line 0.005434 4378 2325 S2-011-103 B 16 Steel LPSW Piping 0.006588 3891.4 2325 S2-011-103 60 Steel CWI Pipe 0.003761 14590 0 S3-012-109 A 10 PVC Storm Drain 1 0.005010 2432 3581 S3-012-109 B 48 Concrete Storm Drain 2 0.004258 11674.5 6514 S2-011-101 A 10 PVC Storm Drain 3 0.005010 2432 3482 S2-011-101 B 10 PVC Storm Drain 6 0.007712 2432 3482 S3-012-102 A 12 Clay Storm Drain 4 0.007296 2912 12619 S3-012-102 B 30 Clay Storm Drain 5 0.004553 7297 12838 1 Detector efficiency is the calibration efficiency multiplied by the licensees correction factors LACBWR Storm Drain 1 is a Class 3 survey unit, in which twenty systematic compliance measurements, two judgmental samples, and one quality control sample were collected during

FSS, for a total of 23 survey unit measurements. The NRC staff noted that sixteen of the 23 measurements fall within a range of 5000 cpm - 7000 cpm in terms of gross activity values, which indicates that the background radiation levels were somewhat consistent. The background value the licensee assigned to this storm drain pipe in the FSS release record was 3,581 cpm, which is well below the observed consistent gross activity range in the data and is therefore reasonably acceptable when comparing the measured results to the DCGL.

LACBWR Storm Drain 2 is a Class 3 survey unit, in which 60 static measurements were obtained during FSS, one at each ten-foot interval with the exception of the final two planned measurements in the last twenty feet of pipe, due to the presence of sediment and river levels.

The background radiation level the licensee assumed in this storm drain pipe was 6,514 cpm.

The NRC staff noted that Storm Drain 2 is a larger, 48 diameter concrete pipe, and therefore some amount of background radiation is expected from the concrete piping materials. In addition, this pipe was considered impacted by the inadvertent release of contaminated water in 2017, which is summarized above as part of the discussion of sample coverage (see Section 3.4.2.1. Therefore, in order to inform the appropriateness of the background radiation value assigned by the licensee, the NRC staff viewed a histogram of the gross activity measurements and observed that the readings under 9,000 cpm are fairly uniformly distributed, which indicates that the background radiation value of 6,500 cpm was appropriate and is therefore reasonably acceptable when comparing the measured results to the DCGL.

LACBWR Storm Drain 4 and Storm Drain 5 are Class 3 survey units, and the storm drain pipes are made of vitrified clay, which would have a higher level of NORM, so it is reasonable that the background radiation would be higher for these pipes. In response to the RAIs associated with the LACBWR FSSR review, the licensee described that during the FSS of Storm Drain 5, higher than expected gross activity measurements were observed. The licensee suspected the clay piping contained NORM, so a piece of the piping was analyzed via onsite gamma spectroscopy.

No plant-derived radionuclides were identified above their minimum detectable activities as a result of the analysis; however, concentrations of K-40, bismuth-214, lead-214 and protactinium-228 were identified. The licensee later obtained another sample from the same clay pipe at the storm drain outfall location and sent the sample to GEL Laboratory for analysis for the full suite of radionuclides identified in Table 5-1, Initial Suite of Radionuclides, of the LACBWR LTP. None of the plant-derived radionuclides analyzed for were positively identified during the offsite analysis of the vitrified clay pipe sample. Therefore, the NRC staff determined that the licensees assumption regarding the background radiation levels in these storm drains being impacted by NORM was reasonable when comparing the measured results to the DCGL.

Furthermore, although the sign test would not have passed in comparison to the Operational DCGL without subtracting background radiation for these four survey units, none of the measurements exceeded the Base Case DCGLs for any of the survey units. The NRC staff noted that the maximum individual dose from the LACBWR buried piping survey units is used as the input to the compliance equation (Equation 6-11 in the LACBWR LTP) which demonstrates that the site, in aggregate, meets the unrestricted release requirements of 10 CFR 20.1402.

Specifically, Storm Drain 1 had the highest measured dose of all the LACBWR buried piping survey units according to the licensees FSS release records, and this dose is therefore used in the compliance equation as the buried piping survey unit input. The dose the licensee calculated for Storm Drain 1 with subtraction of background radiation is 3.0112 mrem/year. The NRC staff calculated the Storm Drain 1 dose if background radiation is not subtracted, and correcting for the source area modification factor, to be approximately 5 mrem/year. In addition, the estimated dose from Storm Drain 2, Storm Drain 4, and Storm Drain 5 without subtracting background radiation and correcting for the source area modification factor would be similar (8.1 mrem/year,

7.2 mrem/year and 6.3 mrem/year, respectively). The staff determined that this hypothetical increase in dose attributed to the LACBWR buried piping does not adversely impact the ability of the site in aggregate to meet the 10 CFR Part 20, Subpart E, criteria for unrestricted release.

3.4.2.4 Radionuclide Mixture Assumptions and Insignificant Radionuclides As noted in Section 5.7.1.8 of the LACBWR LTP, the licensee committed to the collection of sediment samples in the buried piping survey units when available. As part of the RAIs associated with the LACBWR FSSR review, the NRC staff requested clarification on whether sediment samples had been collected for the piping survey units and requested that, for any sediment samples that were analyzed for individual radionuclide activities, the licensee compare the results to the assumed radionuclide mixture fraction used to calculate the Gross Operational DCGL for the LACBWR site. The staff also requested the licensee verify that the dose attributed to the radionuclides assumed to be insignificant contributors was within the assumptions in the LACBWR LTP regarding Insignificant Contributor (IC) dose.

In the RAI response, the licensee clarified that no sediment and/or debris was available to sample during the turnover and FSS of buried piping Survey Units S1-011-102 (CWD Piping),

S2-011-103 A (De-Icing Line), S2-011-103 B (LPSW Piping), S2-011-103 (CWI Piping),

S3-012-109 A (Storm Drain 1), S2-011-101 A (Storm Drain 3), S2-011-101 B (Storm Drain 6),

S3-012-102 A (Storm Drain 4), and S3-012-102 B (Storm Drain 5).

As previously discussed, the licensee collected an actual piece of the piping from the outfall of Storm Drain 5 (Survey Unit S3-012-102 B), which is a 30 internal diameter vitrified clay pipe that had elevated radiation readings suspected due to the presence of NORM. None of the initial suite radionuclides in Table 5-1 of the LACBWR LTP were positively identified during the offsite analysis of the vitrified clay pipe sample from Storm Drain 5. The IC dose calculated for the sample was 0.0810 mrem/year, which is within the assumptions made about the IC dose for piping in Section 5.1 of the LACBWR LTP, and therefore acceptable.

The licensee retrieved the three sediment samples that had been collected during FSS from Storm Drain 2 and sent them to GEL Laboratory for analysis for the full initial suite of radionuclides listed in Table 5-1 of the LACBWR LTP. None of the plant-derived radionuclides analyzed for were positively identified except for Cs-137, which was present at a maximum concentration of 4.97E-02 pCi/g. The maximum IC dose calculated for the samples was 0.0791 mrem/year, which is within the assumptions made about the IC dose for piping in Section 5.1 of the LACBWR LTP, and therefore acceptable.

3.4.2.5 Quality Control Investigations As part of the RAIs associated with the LACBWR FSSR review, the NRC staff requested additional information regarding the quality control investigations associated with various FSS data to evaluate whether the licensee had followed the processes outlined in Section 5.9.3.4, QC Investigations, of the LACBWR LTP. Specifically, certain FSS release records indicated that the QC samples did not meet the acceptance criteria for compared sample results (original samples versus QC samples). Given that this issue affected both the above grade structures and buried piping systems similarly, this topic is evaluated in the section of this evaluation that discusses quality control for above grade structures (see Section 3.5.2.9).

3.4.2.6 Conclusion for Buried Piping Survey Areas For the reasons discussed in the NRC evaluation of the LACBWR buried piping survey units, the NRC staff has reasonable assurance that the FSS release records for these survey units demonstrate that residual radioactivity in the associated buried piping survey areas complies with the unrestricted release criteria. The maximum SOF from all buried piping survey units reported by the licensee was 0.1204, which was associated with Storm Drain 1 and corresponds to a dose of 3.0112 mrem/year. The maximum dose from buried piping that the NRC staff calculated after correcting the source modification factor and conservatively not subtracting background radiation measurements was 8.1 mrem/year associated with Storm Drain 2. This difference in the assumed maximum dose input from buried piping for use in the overall compliance equation will not impact the outcome of the equation related to the site release criteria. Given these considerations, the NRC staff concludes that the release of the LACBWR buried piping survey units will have no adverse impact on the ability of the site to meet the 10 CFR Part 20, Subpart E criteria for unrestricted release.

3.5 Class 2 and Class 3 Remaining Above Ground Structures 3.5.1 Description of Survey Units Table 11 summarizes the LACBWR Class 2 and Class 3 remaining above ground structure survey units, all of which were part of Phase 2 of the FSSR.

Table 11. Class 2 and Class 3 Above Ground Building Survey Units Survey Unit Type Survey Unit Description Phase Class B2-010-101 Building LACBWR Crib House 2 2 B2-010-102 Building Genoa 3 Crib House 2 2 B2-010-103 Building LACBWR Administration Building 2 2 B3-012-101 Building Back-up Control Center 2 3 B3-012-102 Building Transmission Sub-Station Switch House 2 3 B3-012-103 Building Genoa 1 Crib House 2 3 B3-012-104 Building Barge Wash Break Room 2 3 B3-012-109 Building Security Shack 2 3 Survey Unit B2-010-101, LACBWR Crib House The LACBWR Crib House provided circulating water for the condenser and service water systems. Survey Unit B2-010-101 is a Class 2 survey unit consisting of the interior and exterior surfaces of the LACBWR Crib House with a total surface area of 1,060 m2. Per the survey plan, the licensee collected fourteen required systematic measurements for each of the interior and exterior surfaces, for a total of 28 static measurements. The licensee performed surface scanning across approximately 30% of the total surface area in the survey unit. Specifically, the licensee scanned 30 scan areas (one scan area at each systematic measurement location and two judgmental scan areas), covering 322.13 m2 of the survey unit. The FSS release record describes how three alarms were produced during the scanning of the survey unit, but that the static measurements collected at the locations of scan alarms were below the action level.

Survey Unit B2-010-102, Genoa 3 Crib House The Genoa 3 Crib House was used as the circulatory water pumping station for the Genoa 3 coal plant. Survey Unit B2-010-102 is an impacted Class 2 above grade building survey unit consisting of the interior and exterior surfaces of a main building, an east addition, and a south addition. The total surface area of the survey unit is 2,873 m2. The survey unit was split into two sub-survey units (main building and the south addition) in order to accommodate the MARSSIM recommended survey unit size restrictions. Per the survey plan, the licensee obtained fourteen required systematic measurements on the interior and exterior surfaces of each of the two buildings, for a total of 56 static measurements. The licensee performed surface scanning across approximately 25% of the total surface area in the survey unit, which equates to 718 m2.

Survey Unit B2-010-103, LACBWR Administration Building The Administration Building is a two-story metal and brick structure located directly north of the LACBWR Radiologically Contaminated Area, which was used as an office building for staff and as a laboratory for environmental analyses. The Administration Building was classified as a Class 2 structure due to its proximity to the LSE and its previous occupancy by LACBWR facility workers. In addition, the building contained equipment used to conduct whole-body counts. The total surface area of the survey unit is 5,433 m2. The licensee split the survey unit into eight sub-survey units (A through H), with fourteen compliance measurements each, required per the survey plan, in order to accommodate the MARSSIM recommended survey unit size restrictions. For this survey unit, 25% scan coverage was selected for the floor and walls, and 10% scan coverage was selected for the ceilings. This coverage equates to total planned scan coverage of 1,230 m2. During FSS, the licensee scanned 147 scan areas (one scan area at each systematic measurement location and 35 judgmental scan areas), yielding actual scan coverage of 1,345 m2 of the survey unit.

The FSS release record for Survey Unit B2-010-103 describes how a discrete radioactive particle containing approximately 0.005 microcurie of Cs-137 was retrieved during the initial characterization survey for the LACBWR Administration Building. This particle was located on the second floor outside an office location on 12 by 12 tiles. After removal of the particle, the licensee collected ten direct biased survey samples from the first and second floor laminated wood, carpet, and 12 by 12 tile areas. The results of the surveys showed all the beta/gamma and alpha results were well below 50% of the action levels for structural surfaces.

Survey Unit B3-012-101, Back-up Control Center The Back-up Control Center is a two-story building which was utilized for the Genoa 3 coal plant; the survey unit consists of the interior and exterior surfaces of the structure. Survey Unit B3-012-101 is a Class 3 survey unit with a surface area of 1,710 m2. Per the survey plan, the licensee obtained fourteen required measurements and performed scans across fourteen areas (ten 12.4 m2 scan areas and four 12.25 m2 scan areas), covering 173 m2 of the survey unit.

Survey Unit B3-012-102, Transmission Sub-Station Switch House The Transmission Sub-Station Switch House is a one-story building; the survey unit consists of the interior and exterior surfaces of the structure. Survey Unit B3-012-102 is a Class 3 survey unit with a surface area of 861 m2. Per the survey plan, the licensee obtained fourteen required

systematic measurements and performed scans across fourteen areas (seven 6.25 m2 scan areas and seven 6.4 m2 scan areas), covering 88.6 m2 of the survey unit.

Survey Unit B3-012-103, G-1 Crib House The G-1 Crib House is in the North Yard of the LACBWR site and was a tool room for Genoa 3 personnel; the survey unit consists of the interior and exterior surfaces of the structure. Survey Unit B3-012-103 is a Class 3 survey unit with a surface area of 296 m2. Per the survey plan, the licensee obtained fourteen required measurements and performed scans across fourteen areas (one 2.2 m2 scan area at each random measurement location), covering 30.8 m2 of the unit.

Survey Unit B3-012-104, Barge Wash Break Room The Barge Wash Break Room is in the North Yard of the LACBWR site and was utilized as a break room by personnel that worked on barges; the survey unit consists of the interior and exterior surfaces of the structure. Survey Unit B3-012-104 is a Class 3 survey unit with a surface area of 116 m2. Per the survey plan, the licensee obtained fourteen required systematic measurements and performed scans across fourteen areas (one 1 m2 scan area at each random measurement location), covering 14 m2 of the survey unit.

Survey Unit B3-012-109, Security Shack The Security Station is a small one-story building that served as the security force housing and access point to the Dairyland Power Cooperative property; the survey unit consists of the interior and exterior surfaces of the structure. Survey Unit B3-012-109 is an impacted Class 3 above grade building survey unit with a surface area of 122 m2. Per the survey plan, the licensee obtained fourteen required measurements and performed scans across fourteen areas (one 1 m2 scan area at each random measurement location), covering 14 m2 of the survey unit.

3.5.2 NRC Evaluation of Remaining Above Ground Buildings The NRC staff evaluated the licensees final status survey results for the Class 2 and Class 3 impacted above ground buildings and verified that the FSS implementation is adequate to demonstrate that these survey units meet the radiological criteria for license termination, and may therefore be released from the LACBWR 10 CFR Part 50 license. This evaluation involved comparing the licensees implementation of the FSS to the approved survey plan in the LACBWR LTP, and assessing the licensees survey approach against the relevant guidance documents. Specifically, the NRC staff reviewed the licensees beta/gamma surface scans and static measurements, the comparison of the measurement results to the approved release criteria, and the evaluation of each survey unit through use of a statistical test (sign test). The staff also verified that the LACBWR QA/QC program was adequate and appropriately implemented for the FSS, and that suitable instrumentation, with sufficient sensitivities, proper calibrations, and adequately trained personnel, were used for radiological surveys, scans, and measurements, as described in the FSS plan. A discussion of specific topics that received an in-depth review during the NRC staffs evaluation is presented below.

3.5.2.1 Survey Scan Coverage Section 5.6.4.4 of the LACBWR LTP specified the survey scan coverage requirements. Class 2 survey units require between 10-100% scan coverage, while Class 3 survey units do not have a minimum scan requirement, although the licensee scanned a minimum of 10% for the Class 3

survey units. For Class 3 survey units, judgmental (biased) surface scans will typically be performed on areas with the greatest potential for radiological contamination.

As shown in Figure 5 below (reproduced from Figure A.3, Examples of Scanning Patterns for Each Survey Unit Classification, in MARSSIM), the examples for scanning patterns in Class 2 or Class 3 survey areas show continuous serpentine lines of scans that are less dense than those for Class 1 survey areas. The purpose of scanning during FSS is to identify locations within the survey unit that exceed the investigation levels established in the LACBWR LTP.

These locations are intended to be marked and receive additional investigations to determine the concentration, area, and extent of the radiological contamination.

As part of the RAIs associated with the LACBWR FSSR review, the NRC staff requested that the licensee provide the locations of the survey scans for above grade structures. The licensee described that the scans were conducted in grids that surrounded each static sample location generated by the VSP software tool. The licensees RAI response specifically stated that:

The field notes, for each survey unit, indicate the area scanned around each static location (random, systematic, and judgmental). With the exception of survey unit B2-010-101 (see RAI 1(f)), there were no scan alarms encountered during the FSS of above grade buildings. All scan results are provided in Table 7-1 within each release record. Given that the amount of surface area, where scan surveys were conducted, was provided (thus ensuring the minimum scan frequency was met) with the results for each scan, LaCrosseSolutions does not believe there is added value in depicting the scan locations on figures provided in the release records for above grade building survey units.

The licensee provided additional information on the conduct of scans for the above grade structures in LACBWR procedure LC-FS-PR-015, Final Status Surveys for Structures, which instructs the user that if less than 100% scan coverage is required, designate areas to be scanned using the reference grid system that equates to the required total area to be scanned, and document the basis for selecting those areas. In practice at LACBWR the surveyor scanned a small area around each static measurement location. That is, instead of performing a less dense serpentine scan of the entire Class 2 survey unit as depicted in MARSSIM (see Figure 5), the licensee performed a denser scan in a grid that was located around each of the systematic locations indicated by VSP. The NRC staff also noted that in the LACBWR Administration Building, staff were not able to determine from the associated FSS release record whether biased scans had been performed in the area where a discrete radioactive particle had been retrieved on the second floor of the building during characterization. However, given that subsequent survey scans of this area during characterization showed that all contamination had been removed, additional biased scans during FSS were not necessary.

Although judgmental surface scans would typically be performed in Class 3 survey units on areas with the greatest potential for radiological contamination, the licensee explained that at LACBWR, in the absence of any peculiar features identified during the survey unit walkdown that would indicate contamination, surveyors performed scans surrounding the random static measurement locations. While, in general, the licensees approach for survey scan locations does not follow the typical MARSSIM examples for scanning patterns (see Figure 5), the NRC staff finds the surface scans conducted at LACBWR were reasonably adequate due to the low levels of radioactivity present in the above grade buildings (e.g., nearly all static measurements were less than the Operational DCGL release criteria) and because the historical radiological information for the Class 2 and Class 3 remaining above ground structures did not provide evidence of increased contamination potential in most buildings.

Figure 5. Examples of Scanning Patterns for Each Survey Unit Classification (Reproduced from MARSSIM, Revision 1)

3.5.2.2 Detector Efficiency, Scan MDC, and Static MDC The licensee used a combination of surface scanning and surface static measurements with a Ludlum Model 44-116 beta/gamma radiation detector to conduct the FSS activities for the LACBWR remaining above ground buildings. The licensee used calibrated detector efficiencies (shown in Table 7-2, Detector Efficiencies, of the relevant FSS release records) during the performance of FSS. In response to the RAIs associated with the LACBWR FSSR review, the licensee clarified that technetium-99 (Tc-99) was used to calibrate the detector. The efficiencies used for the Ludlum Model 44-116 beta/gamma radiation detector in the relevant FSS release records range from 15% to 24%. For additional information on radiation detector efficiency see the assumed radionuclide mixture discussion for above grade buildings (Section 3.5.2.8).

The licensee calculated the scan and static MDC values for the remaining above ground structures using the equations in LACBWR procedure LS-FS-PR-015, Revision 2, Attachment 6, which match Equation 6-10 and Equation 6-7 in MARSSIM. For the associated Class 2 survey units, the static MDC was sufficient to detect residual radioactivity at the licensees defined direct investigation level of 3,160 dpm/100 cm2 (LACBWR Adjusted Gross Operational DCGL).

For the associated Class 3 survey units, the static MDC was sufficient to detect residual radioactivity at the licensees defined direct investigation level of 1,580 dpm/100 cm2 (i.e., 50% of the LACBWR Adjusted Gross Operational DCGL).

Specifically, the formula used to determine the scanning MDC at the 95% confidence level is:

60 d

=

( )

100 Where: MDCscan = minimum detectable concentration in dpm/100 cm2 d = index of sensitivity (1.38) i = observation interval (seconds) bi = background counts per observation interval t = total efficiency p = surveyor efficiency (0.5)

A = detector area in cm2 (not to exceed 126 cm2)

The NRC staff noted that the licensee incorrectly used a value of 100 cm2 for the effective probe area of the radiation detector when the value of the physical probe area for the Ludlum 44-116 detector, which is 126 cm2, should have been used. This error affects both the MDC calculations and the conversion of gross activity cpm to net dpm/100 cm2. Section 6.6.1, Surface Activity, of MARSSIM points out that this is a common error when addressing effective probe area:

When measuring surface activity, it is important to account for the physical surface area assessed by the detector in order to make probe area corrections and report data in the proper units (i.e., dpm/100 cm2). This is termed the physical probe area. A common misuse is to make probe area corrections using the effective probe area which accounts for the amount of the physical probe area covered by a protective screen. Figure 6.1 illustrates the difference between the physical probe area and the effective probe area. The physical probe area is used because the reduced detector response due to the screen is accounted for during instrument calibration.

The NRC staff evaluated the significance of this error regarding the effective probe area for the radiation detector used to survey the LACBWR remaining above ground buildings and determined it would not impact compliance with the unrestricted release criteria. This is because if the license had applied the correct value for the detector area, the overall scanning MDC would have been lower. Similarly, the calculated dpm/100 cm2 would have also been lower. This means that the error was conservative and the resulting FSS measurements do not impact the overall conclusions with respect to the acceptability of the survey units for release.

3.5.2.3 Number of Samples and Sample Location Section 5.6.4.1 of the LACBWR LTP specified that the licensee would determine the sample size (N) for the compliance measurements necessary to ensure sufficient data for statistical analysis in each survey unit following the guidance in NUREG-1757 and MARSSIM. The number of sampling and measurement locations collected from the survey unit were determined by establishing the acceptable Type I and Type II decision errors, calculating the relative shift, and using Table 5-5 of MARSSIM. The licensee applied a relative shift of three for all the above grade buildings because the calculated value of the relative shift was larger than three. The LACBWR LTP committed to using a Type I and Type II decision error of 5% and applying the sign test. The sample size from Table 5.5 of MARSSIM that equates to a Type I and Type II decision of 5% for use with the sign test is an N value of fourteen samples. Therefore, the staff confirmed that the licensee intended to collect at least fourteen static systematic measurements for the Class 2 and Class 3 remaining above ground structures.

For Class 2 survey units, the sampling and measurement locations were informed based on a systematic grid with a random starting point. The licensee used VSP to determine the systematic location grids. The licensee clarified during the RAI process that a scan was conducted in a small grid around each sampling location that VSP determined. Then, the static measurement was collected at the location within that grid with the highest measured activity.

The total surface area of each grid scanned was dependent on the total surface area of the survey unit and the number of locations, but ensured that at least 10% of the Class 2 survey unit area was scanned. The maps in the associated FSS release records show the location of each scan grid, but not necessarily the exact location of each static measurement.

Section 5.5.3, Developing an Integrated Survey Strategy, of MARSSIM notes that the systematic measurements are intended to be unbiased, and discusses that systematic grids are used for Class 2 survey units because there is an increased probability of small areas of elevated activity. The use of a systematic grid allows the decision maker to draw conclusions about the size of the potential areas of elevated activity based on the area between measurement locations. The random starting point of the grid provides an unbiased method for obtaining measurement locations to be used in the statistical tests.

For Class 3 survey units, random static measurement patterns were used to ensure that the measurements are independent and support the assumptions of the statistical tests. The random locations of the fourteen static measurements per survey unit were generated using the random-number generator feature in VSP. The licensee marked the fourteen random static measurement locations based on the dimensions provided in the survey unit map that accompanied each FSS release record for the Class 2 and Class 3 above grade buildings.

The NRC staff note that it is important that survey maps be included in the FSS release records indicating the precise sample locations of the static measurements. NUREG-1757 provides guidance on the information to be submitted within release records, including a map or drawing

of the survey unit showing the reference system and random start systematic sample locations for Class 1 and 2 survey units, and random locations shown for Class 3 survey units and reference areas. For the LACBWR above grade building FSS release records, the licensees approach for deciding the precise location of the static measurements for Class 2 above grade buildings (based on scan readings within the grids around the VSP sample locations) was not clear in the original release records. However, because the licensee clarified their approach in response to the RAIs, and because the static measurements were below the approved site release criteria, the NRC staff find the information submitted reasonably adequate.

3.5.2.4 Release Criteria for LACBWR Above Grade Buildings The licensee compared the survey measurements collected in the LACBWR Class 2 and Class 3 remaining above ground structures to the radiological screening values for building surface contamination from Table H.1 of Appendix H, Criteria for Conducting Screening Dose Modeling Evaluations, of NUREG-1757, Volume 2. Table 2-3, Base Case and Operational DCGLs for the Above-Grade Buildings, of Phase 2 of the LACBWR FSSR provides the Base Case DCGLs (DCGLAGB) and the Operational DCGLs (OpDCGLAGB) for the main ROCs that were used during the FSS of the remaining above ground structures. The NRC staff evaluated the licensees survey measurements against these values to determine whether the residual radioactivity in the associated survey areas complies with the unrestricted release criteria.

3.5.2.5 Investigation Samples and Scan Action Levels Section 5.6.4.6 of the LACBWR LTP states that survey areas exceeding a given investigation level will be addressed by further biased surveys and sampling as necessary according to the investigation levels in Table 5-16 of the LACBWR LTP. For Class 1 and Class 2 survey areas, the direct investigation level is a survey result greater than the Operational DCGL. For Class 3 survey areas, the direct investigation level is a survey result greater than 50% of the Operational DCGL. For the Class 2 and Class 3 remaining above ground structures the licensee set the scan action level (also referred to as the scan alarm level) to the average background radiation plus the minimum detectable count rate for the surveyor (MDCRSurveyor). The MDCRSurveyor was calculated as discussed in Section 6.7.2, Scanning Sensitivity, of MARSSIM.

According to the FSS release records, scan alarms occurred only in the LACBWR Crib House (Survey Unit B2-010-101). As part of the RAIs associated with the LACBWR FSSR review, the NRC staff asked whether the static measurements collected in the LACBWR Crib House were considered investigation measurements in response to the scan alarms. Specifically, the NRC staff noted that there were scan alarms in the survey unit, but Table 7-1, Synopsis of Scan Results, of the LACBWR Crib House FSS release record lists zero under the Investigation Measurement column, and Section 9, Investigation and Results, states that no investigations were performed during the performance or analyses of the survey.

In response to the RAIs, the licensee clarified that the static measurements collected in the LACBWR Crib House were not considered investigation measurements. The response states:

The three static measurements in question (B2-010-101-FSRC-A07-BD, B2-010-101-FSRC-A10-BD, and B2-010-101-FSWM-B01-BD) were not considered investigation measurements due to the nature of the survey instructions provided in the sample plan, which consists of scanning a grid in serpentine fashion and collecting a one-minute static measurement at the location of highest scan indication. In this sense, the three systematic static

measurements, which did not produce alarms, were adequate to ensure that no further action was needed. As a result, investigations (i.e., additional measurements) were not conducted.

The NRC staff noted that the three scan alarms in this survey unit were only slightly higher than the alarm threshold level. Given that the static measurements were taken at the location of the highest scan reading within the scan grid, and that the static measurements were below the investigation level, the NRC staff finds the licensees approach for this survey unit acceptable.

3.5.2.6 Segmentation of Survey Units and the Sign Test MARSSIM provides guidance on the maximum survey unit size for buildings. Class 2 building survey units have a suggested size from 100 m2 to 1000 m2 and Class 3 survey units have no size limit. Each survey unit is a defined area consisting of structures of a specified size for which a separate decision will be made to judge whether the area meets the criteria for unrestricted release. Using this approach, each survey unit will meet, or fail to meet, the release criteria independently of all the other survey units. For the LACBWR Class 2 building survey units that exceeded 1000 m2, the licensee split the survey unit into sub-survey units to comply with the size suggestions. For example, the LACBWR Crib House was divided into the exterior and interior surfaces, and each sub-survey unit had fourteen required systematic samples collected.

The licensee conducted the sign test to demonstrate coherence with the statistical principles of the DQO process. The NRC staff noted that when conducting the sign test, the licensee treated all systematic measurements from each above grade building as if they were collected from the same survey unit, instead of conducting the sign test separately for each sub-survey unit of the LACBWR Class 2 and Class 3 remaining above ground structures. For example, all 28 systematic survey measurements from the LACBWR Crib House were evaluated as one group, instead of using the sign test to evaluate the fourteen samples from the exterior and interior surfaces separately. In order to confirm compliance with the unrestricted release criteria, the NRC staff performed an independent evaluation and verified that that the LACBWR Class 2 and Class 3 above grade building survey units would have passed the sign test if the statistical test had been conducted on each individual sub-survey unit.

3.5.2.7 Background Measurements As part of the RAIs associated with the LACBWR FSSR review, the NRC staff requested additional information on the licensees procedure for determining background radiation in the LACBWR above grade buildings, as well as a discussion of the licensees adherence to commitments in Section 5.6.4.2, Statistical Tests, of the LACBWR LTP regarding subtraction of background radioactivity when evaluating survey data using the sign test statistical test, as described in the associated LACBWR FSS release records.

Section 5.6.4.2 of the LACBWR LTP states that the sign test will be applied when demonstrating compliance with the unrestricted release criteria without subtracting background.

Contrary to this commitment in the LACBWR LTP, it appears that for the above grade building and buried piping survey units at LACBWR, background radioactivity was subtracted prior to comparing the survey data to the unrestricted release criteria. For example, in the release record for the Genoa 3 Crib House (Survey Unit B2-010-102), which is a Class 2 survey unit, Section 7, Survey Results, of the FSS release record states that background was subtracted from all measurements, then the measurements were converted from cpm to dpm/100 cm2 (net cpm divided by detector efficiency) for direct comparison to the Adjusted Gross DCGLs.

In the RAI regarding background radiation measurements, the NRC staff requested clarification surrounding the way the licensee was using the term gross activity in the FSSR data tables and whether the licensee had subtracted background. As part of the RAI response, the licensee clarified that the data labeled gross in the above grade building survey unit FSS release records represents residual radioactivity minus background activity. In these survey units, the licensee used the term gross activity to indicate that the values represent the total surface activity of all ROCs that the licensee compared to the Adjusted Gross DCGL. The NRC staff notes that the licensees presentation of the term gross was not accurate. Generally, the terms Adjusted Gross DCGL, gross activity, net activity, etc. should not have a site-specific definition.

Section 6.6.1, Surface Activity, of MARSSIM discusses the difference between instrument background and background radiation reference areas, stating that some instruments have background counts associated with the operation of the instrument. A correction for instrument background can be included in the data conversion calculation as shown in Equation 6-3. Note that the instrument background is not the same as the measurements in the background reference area used to perform the statistical tests. The Ludlum manufacturers specification for the Ludlum Model 44-116 beta scintillation radiation detector lists the typical instrument background as 300 cpm or less. The background radiation measured in the LACBWR above grade buildings ranged from 150 cpm to 588 cpm during the associated survey activities.

The NRC staff also asked the licensee to clarify how the background level of radioactivity in the LACBWR above grade buildings was measured. In response, the licensee stated that background reference areas were not used. Instead, for each survey unit, background radiation measurements were obtained within the survey unit by bringing the unshielded Ludlum Model 44-116 detector to waist height, turning it around so that the detection window is facing away from the surface of interest, taking five one-minute static counts, and averaging those five measurements to determine an ambient background for a certain part of the survey unit. The licensee selected background measurement locations in an attempt to provide a representative spread of ambient background. For example, five backgrounds could have been collected on one building elevation or in a single room (a typical method is four corners and the center).

The NRC staff noted that although background radiation is not typically subtracted from survey measurements when using the sign test, subtracting a background radiation level from the surface activity measurements when calculating a dpm/100 cm2 value can be appropriate under certain situations. NUREG-1505, A Nonparametric Statistical Methodology for the Design and Analysis of Final Status Decommissioning Surveys (ADAMS Accession No. ML061870462),

Section 12.3, Using Paired Observations for Survey Units with Many Different Backgrounds, discusses examples using a paired background reference area and survey unit measurements with the sign test. This guidance is applicable when there are many different radioactive materials within a single survey unit and dividing the area into separate survey units, each with a different background reference area, would not be practical or consistent with the dose models. For example, if a walkway was paved with different types of concrete or the building made with different materials. In this type of scenario, each survey unit measurement would be paired with a suitable background radiation reference material and the sign test performed on the difference between the two values across the survey unit. However, the way the licensee leveraged this approach to select background radiation values for the LACBWR Class 2 and Class 3 above grade building survey units may not have been appropriate because, in many instances, the measured radiation value was lower than the background radiation value.

When reviewing the associated FSS data, the NRC staff noted that the subtraction of background radiation from the survey measurements resulted in an abundance of negative

values, which were then converted to zeros before applying the sign test to the survey unit. The abundance of negative values indicates that the background radiation assigned may not have been appropriate to these survey units. While the sign test can be used with data from which background radiation has been subtracted for surface activity measurements, this approach requires careful selection of the background reference material. In this circumstance, given the abundance of negative values produced when background radiation was subtracted, the NRC staff does not view the subtraction of background values before applying the sign test to the LACBWR Class 2 and Class 3 above grade building survey units as appropriate. However, the NRC staff performed an independent confirmatory analysis of the above grade building survey units without subtracting background radiation from the surface activity measurements collected during FSS, and confirmed that all the survey units still pass the sign test. Therefore, because the NRC staffs independent evaluation verified that that the LACBWR Class 2 and Class 3 above grade building survey units would have passed the sign test without subtracting the ambient background radiation values, the staff finds these survey units acceptable for release.

3.5.2.8 Assumed Radionuclide Mixture for Above Ground Building Survey Units As part of the RAIs associated with the LACBWR FSSR review, the NRC staff requested additional information to demonstrate that the assumed radionuclide mixture for the eight above grade buildings at LACBWR was appropriate. In Section 5.2.9, Surrogate Radionuclides, of the LACBWR LTP, the licensee appears to commit to using a ratio of 0.502 for Sr-90 to Cs-137 as the surrogate radionuclide ratio for above grade structures. Contrary to this commitment, a surrogate ratio of 0.502 for Sr-90 to Cs-137 does not seem to have been used based on the associated FSS release records for the LACBWR Class 2 and Class 3 above grade structure survey units. In light of this information, the NRC staff asked the licensee to explain the alternative method that was used to determine the HTD radionuclide ratio for above grade structures given that the HTD radionuclide ratios influence radiation detector efficiency.

For the LACBWR above ground structures, compliance with the unrestricted release criteria was demonstrated through a combination of surface scanning and static measurements using a Ludlum Model 2350-1 data logger paired with a Ludlum Model 44-116 radiation detector with a 125 cm2 detector area. The licensee collected static measurements in cpm, subtracted background radiation, and converted the net cpm to dpm/100 cm2 by dividing by the detector efficiency, which should account for an assumed radionuclide mixture. The resulting measurement value in dpm/100 cm2 was compared to a Gross Operational DCGL and Gross Base Case DCGL to determine compliance with the approved release criteria.

Similarly, the licensee calculated the Gross Operational DCGL value by assuming mixture fractions for the ROCs from Table 4-1, Dose Significant Radionuclides and Mixture for Above Grade Buildings, of the FSS release records for the LACBWR Class 2 and Class 3 above grade structure survey units (replicated below in Table 12). This table appears contrary to the commitment in Section 5.2.9 of the LACBWR LTP to use a surrogate ratio of 0.502 for Sr-90 to Cs-137 for above grade structures. Instead, as noted in the table below, Sr-90 is about 10% of the radionuclide mixture fraction assumed for above grade buildings. This radionuclide mixture ratio is derived from approximately 40 concrete cores taken from the Waste Gas Tank Vault (WGTV), Reactor Building, Tunnel, and Waste Treatment Building (WTB) during site characterization, which may not be representative of the radionuclide mixture ratio in above grade buildings. (See Table 6-3, Initial Suite of Potential Radionuclides and Mixture Fractions, of the LACBWR LTP, and TSD RS-TD-313196-001, Radionuclides of Concern During LACBWR Decommissioning, Revision 5 (ADAMS Accession No. ML19007A040), Table 22.)

Table 12. Dose Significant Radionuclides and Mixture for Above Grade Buildings Radionuclide Fraction of Total Activity (normalized)

Co-60 0.0644 Sr-90 0.0981 Cs-137 0.829 Eu-152 0.00549 Eu-154 0.00281 Because the radionuclide mixture ratios can influence both the instrument efficiency of the Ludlum Model 44-116 radiation detector (which is used to convert the cpm value to dpm/100 cm2) and the Gross Operational DCGL (which is compared to the dpm/100 cm2 value to calculate the SOF for each measurement), the radionuclide mixture ratios should be verified, or shown to be conservative, given the potential variation in relative radionuclide concentration throughout the survey units for above grade buildings. For example, if the radionuclide mixture comprised 20% Co-60 and 80% Cs-137, without any Sr-90, Eu-152, or Eu-154 present, the Gross Operational DCGL would be 2,820 dpm/100 cm2 instead of 3,160 dpm/100 cm2. Similarly, one would expect the instrument efficiency of the Ludlum Model 44-116 radiation detector to change with a different assumed radionuclide mixture.

Although Chapter 5 of the LACBWR LTP states that calibration for the Ludlum Model 44-116 radiation detector typically uses Cs-137, the licensee clarified in the RAI responses related to the LACBWR FSSR review that Tc-99 was used to calibrate the detector. Instead, the licensee used actual calculated detector efficiencies (shown in Table 7-2 of the relevant FSS release records) during the performance of FSS. The actual efficiencies used for the Ludlum Model 44-116 detector in the relevant FSS release records range from 15% to 24%. The RAI response further explains that since the beta energy for Tc-99 is lower than that of the ROCs when accounting for intensity, the detector efficiency assumed was lower than the true efficiency, thus conservatively overestimating the dpm/100 cm2.

The NRC staff reviewed the beta energies of the ROCs for LACBWR and verified that Tc-99 does have an overall lower weighted beta energy. Table 13 below summarizes the beta energy emissions for the ROCs, as compared to the beta emission energy for Tc-99. As shown in the table, Tc-99 has a lower beta energy than Co-60 and Sr-90; however, while Eu-152 and Eu-154 have some beta emissions of lower energy than Tc-99, these beta energies also have a lower emission percentage, which impacts the overall instrument efficiency.

Table 13. Beta Radiation Data Beta Radiation Data Avg Max Avg Max BR (Sum Max T1/2 Intensity Avg (1) Weighted Weighted Nuclide Energy Energy Energy x Energy x Intensity Energy (year) (%) (keV) Avg (keV) Max (keV)

(keV) (keV) Intensity Intensity /100) (keV)

Co-60 5.27E+00 95.77 317.05 99.88 9566 31667 1 96.41 96.41 1490.29 318.46 625.87 1490.29 0.12 75 179 Sr-90 2.82E+01 195.8 546 100.00 19580 54600 1 195.80 195.80 546.00 546.00 Tc-99 2.11E+05 84.6 293.5 100.00 8460 29350 1 84.60 84.60 293.50 293.50 Cs-137 3.01E+01 174.32 513.97 94.70 16508 48673 1 187.14 187.14 1175.63 549.04 416.26 1175.63 5.30 2206 6231 Eu-152 1.35E+01 47.38 175.5 1.83 87 321 0.28 82.99 297.45 1474.60 874.29 58.49 213.3 0.11 6 23 112.34 384.9 2.43 273 935 221.69 695.7 13.73 3044 9552 226.9 709.7 0.26 60 187 295.12 888.4 0.28 84 252 364.69 1063.5 0.91 333 971 535.49 1474.6 8.24 4412 12151 Eu-154 8.61E+00 69.3 249.2 28.60 1982 7127 1 221.1643 221.1643 1845.7 668.7895 87.5 307.9 0.82 72 253 92.3 323 0.17 16 56 101.5 351.7 1.58 161 557 129.9 437.5 0.32 42 140 169 550.7 0.11 18 58 176.4 571.3 36.30 6403 20738 225.2 705 0.73 164 513 229.7 717.2 0.30 69 215 276.8 841 16.80 4650 14129 307.98 921.2 0.13 40 121 328.3 972.5 3.50 1149 3404 401.2 1153.3 0.70 281 807 588.1 1597.8 0.19 112 304 695.8 1845.7 10.00 6958 18457 1 Excludes emission intensities less than 0.1%; source https://www.nndc.bnl.gov/chart/; weighted averages and maximums are weighted based on intensity.

Given that Tc-99 has a lower beta energy emission level, the detector conversion from cpm to the calculated dpm/100 cm2 would be higher due to the lower instrument efficiency utilized to calibrate against Tc-99 as compared to the specific radionuclide mixture present in the above ground structures. The NRC staff noted that the NRC does not typically base radiation detector calibration and efficiency on just one radionuclide as was done for LACBWR. Instead, the NRC would use a weighted efficiency calculation which considers the specific radionuclide mixture and several calibration points for the detector model. However, in this instance, since Tc-99 yields a lower detector efficiency than would be calculated using weighted efficiencies for the specific radionuclide mixture, the calculated dpm/100 cm2 would be overestimated to a degree.

The NRC staff also asked the licensee to provide information regarding how the survey approach used for the LACBWR above grade buildings accounted for the 10% IC radionuclide dose that was committed to in Section 6.14.1, Insignificant Contributor Dose and Radionuclides of Concern, of the LACBWR LTP. This section of the LTP states that the IC dose percentage assigned to adjust the DCGLs for the ROC in all media (soil, basements, buried pipe, and above grade buildings) is increased to 10 percent. The licensee responded by acknowledging that the

adjusted DCGLs utilized for the surveys of the above grade buildings at LACBWR were not adjusted for the 10% IC dose, but that the utilization of Tc-99 to determine the instrument efficiency would compensate for the IC dose for the above grade buildings.

In summary, the licensee did not strictly follow the commitment in the LACBWR LTP concerning HTD and IC radionuclides in their approach to surveying the above grade building as follows:

• The concentration of Sr-90 relative to other potential radionuclides was not verified in 10% of the samples taken during FSS for each of the survey units (Section 5.1 of the LACBWR LTP).

• The licensee did not assume a surrogate ratio of 0.502 for Sr-90 to Cs-137 in the derivation of the Adjusted Gross DCGLs for above grade structures (Section 5.2.9 of the LACBWR LTP).

• The adjusted DCGLs utilized for the above grade buildings were not adjusted for the 10% IC dose (Section 6.14.1 of the LACBWR LTP).

The NRC staff evaluated the derivation of the radiation detector efficiency assumed by the licensee and compared this to the detector efficiency that would result from calculating a weighted efficiency for the specific radionuclide mixture present at LACBWR. Given that the licensees range of efficiencies is lower than the site-specific radionuclide mixture weighted efficiency, the values the licensee assigned for dpm/100 cm2 are adequately conservative.

Furthermore, since the licensee was using a beta/gamma detector for survey measurements, if Sr-90 was present, the detector would have responded to its presence, which diminishes the importance of the surrogate ratio and verification of the ratio for Sr-90. Therefore, even though the licensee did not strictly follow the LACBWR LTP commitments summarized above, the measurements reported in the FSS release records for the LACBWR Class 2 and Class 3 above grade building survey units are reasonably conservative and, therefore, acceptable.

3.5.2.9 Quality Control As part of the RAIs associated with the LACBWR FSSR review, the NRC staff requested additional information regarding the quality control investigations for the FSS data.

Section 5.9.3.4, QC Investigations, of the LACBWR LTP states that:

If QC replicate measurements or sample analyses fall outside of their acceptance criteria, a documented investigation will be performed in accordance with approved procedures; and if necessary, shall warrant a condition report in accordance with approved corrective action procedures. The investigation will include verification that the proper data sets were compared, the relevant instruments were operating properly, and the survey / sample points were properly identified and located. Relevant personnel will be interviewed, as appropriate, to determine if proper instructions and procedures were followed and proper measurement and handling techniques were used including chain of custody, where applicable. If the investigation reveals that the data is suspect and may not represent the actual conditions, additional measurements will be taken. Following the investigation, a documented determination is made regarding the usability of the survey data and if the impact of the discrepancy adversely affects the decision on the radiological status of the survey unit.

The NRC staff noted that several FSS release records contained information in Attachment 4, Quality Control Assessment, that indicated the LACBWR QC survey samples did not meet the acceptance criteria for compared sample results (original survey samples versus QC samples).

The licensee stated that since the values were well below the Operational DCGL, no further review or action was necessary, instead of investigating and, if necessary, issuing a condition report as outlined in Section 5.9.3.4 of the LACBWR LTP. The affected survey units include the following above ground structures and buried piping systems:

• LACBWR Crib House (Survey Unit B2-010-101)

• Genoa 3 Crib House (Survey Unit B2-010-102)

• LACBWR Administration Building (Survey Unit B2-010-103)

• Back-up Control Center (Survey Unit B3-012-101)

• Transmission Sub-Station Switch House (Survey Unit B3-012-102)

• G-1 Crib House (Survey Unit B3-012-103)

• Barge Wash Break Room (Survey Unit B3-012-104)

• Security Shack (Survey Unit B3-012-109)

• CWD Pipe (Survey Unit S1-011-102)

• De-Icing Line (Survey Unit S2-011-103 A)

• Storm Drain 4 (Survey Unit S3-012-102 A)

The NRC staff also noted that comparison of the QC sample results to the Operational DCGL is not an adequate quality assurance criterion. As part of the RAI, the NRC staff requested that the licensee reevaluate the rationale for using the Operational DCGL as a quality assurance criterion for assessing FSS data, as well as provide an alternative quality assurance criterion or discussion of the QC investigation process as described Section 5.9.3.4 of the LACBWR LTP.

Using the Operational DCGL as a quality acceptance criterion would imply that survey samples could be quite different from one another, yet if they are both below the Operational DCGL, they would pass the quality control comparison. Therefore, the use of the Operational DCGL as a criterion for quality control would not meet the intent of the quality control comparison.

As part of the associated RAI response, the licensee performed a review of all the FSS data for all of the LACBWR survey units to ensure that the QA/QC protocols described in the sites Quality Assurance Program Plan and Section 5.9 of the LACBWR LTP were followed. The licensees response also clarified the acceptance criteria for replicate static measurements. The acceptance criterion for replicate static measurements (which are the quality control measurements taken for above ground structures) is defined as the replicate measurement being within 20% of the standard measurement. The licensees response also stated that in addition, the Radiological Engineer would also assess the dose represented by each measurement to determine agreement. The NRC staff reviewed this information and noted that, while the level of radioactivity and the proximity to the MDC of the replicate and static measurements may be considered given the MDCs impact on uncertainty, the NRC reiterates that comparison to the Operational DCGL is not an adequate quality assurance criterion.

The NRC staff independently reviewed the instances in the LACBWR above ground building FSS release records where the data indicated that the QC samples did not meet the stated 20%

acceptance criterion between the replicate and standard measurements. The NRC staff noted that instead of comparing the gross activity measurements, the licensee compared the replicate and standard sample measurements after subtracting background radiation (net dpm/100 cm2).

Therefore, for confirmatory purposes, the NRC staff instead compared the gross activity measurements when assessing the QC samples. In most instances, when comparing the gross

activity measurements, the QC acceptance criterion of 20% was met. When agreement within 20% was not satisfied, the measurements proximity to the MDC is considered to be a reasonable explanation for why the criterion was not met. Given that most of the QC sample measurements passed when comparing the gross activity measurements, and since the measurements that did not pass were close to the MDC, the NRC staff finds the QC samples for these survey units adequate.

3.5.2.10 Conclusion for Above Ground Structures For the reasons discussed in the NRC evaluation of the LACBWR Class 2 and Class 3 remaining above ground structures, the NRC staff has reasonable assurance that the FSS release records for these survey units demonstrate that residual radioactivity in the associated above ground building areas complies with the unrestricted release criteria. The maximum SOF from all the above ground structure survey units reported by the licensee was 0.0202, which was associated with the LACBWR Crib House and corresponds to a dose of 0.5055 mrem/year.

Given these considerations, the NRC staff concludes that the release of the LACBWR Class 2 and Class 3 remaining above ground structure survey units will have no adverse impact on the ability of the site to meet the 10 CFR Part 20, Subpart E criteria for unrestricted release.

4.0 NRC INSPECTIONS AND CONFIRMATORY SURVEYS NRC inspectors and survey contractors from the Oak Ridge Associated Universities (ORAU) performed multiple inspection activities, as well as in-process and confirmatory surveys of the radiological conditions at LACBWR, throughout the decommissioning process, with a particular focus on the expanded decommissioning activities undertaken after the June 1, 2016, license transfer from DPC to LS. ORAU also performed confirmatory laboratory analysis of samples collected from the site. Note that the LACBWR Class 2 and Class 3 open land area survey units received confirmatory surveys as discussed in the ORAU report titled Remaining Land Areas.

Reports associated with the ORAU confirmatory surveys and sample analyses were provided on January 23, 2017 (ADAMS Accession No. ML17024A021, Confirmatory Survey Results for Non-Impacted Land Areas), March 23, 2018 (ADAMS Accession No. ML20296A507, Confirmatory Survey of Turbine Building Survey Unit L1010102), June 20, 2018 (ADAMS Accession No. ML19007A032, Confirmatory Survey Results for Circulating Water Discharge Interior Piping), June 26, 2019 (ADAMS Accession No. ML20296A513, Confirmatory Survey Results for Reactor Building Basement), and January 10, 2020 (ADAMS Accession No. ML20296A519, Confirmatory Survey Results for Remaining Land Areas). NRC inspections of the LACBWR decommissioning and survey activities are documented in inspection reports dated July 27, 2016 (ADAMS Accession No. ML16210A435), March 16, 2017 (ADAMS Accession No. ML17080A143), February 12, 2018 (ADAMS Accession No. ML18043B109),

February 13, 2019 (ADAMS Accession No. ML19045A237), October 21, 2019 (ADAMS Accession No. ML19294A284), October 8, 2020 (ADAMS Accession No. ML20282A553), and January 7, 2022 (ADAMS Accession No. ML22005A144).

The NRC inspectors reviewed the licensees survey results, survey methodology, and plans for demonstrating that the survey results would confirm that the remaining structures and areas at LACBWR met the acceptable radiological levels for unrestricted release. The NRC staff also reviewed confirmatory and in-process radiation and contamination surveys conducted by ORAU. Confirmatory surveys provide confidence that the licensees survey results are representative of the conditions for that survey unit. In-process surveys provide confidence that the licensees survey results are accurate. Based on the data review, discussions, and ORAU

and NRC staff observations, the NRC inspectors observed that the licensee had in place methods for demonstrating compliance with the unrestricted release criteria.

In summary, NRC inspections and ORAU confirmatory surveys corroborated that the radiological conditions of the LACBWR Class 2 and Class 3 survey units, as well as the one Class 1 buried piping survey unit, proposed to be released from the 10 CFR Part 50 license met the approved site-specific DCGLs, and that LACBWRs radiological laboratory data were consistent and in agreement with the ORAU analytical results.

5.0 EVALUATION OF THE NEED FOR NRC/EPA LEVEL 2 CONSULTATION The NRC and the U.S. Environmental Protection Agency (EPA) entered into a Memorandum of Understanding (MOU) for Consultation and Finality on Decommissioning and Decontamination of Contaminated Sites on October 9, 2002 (ADAMS Accession No. ML022830208). The MOU provides that, unless an NRC-licensed site exceeds any of three trigger criteria contained in the MOU, the EPA agrees to a policy of deferral to the NRC for decisions on decommissioning, without the need for consultation. For sites that trigger the criteria in the MOU, the NRC will consult with the EPA at two points in the decommissioning process: (1) prior to NRC approval of the licensees LTP or Decommissioning Plan, which the NRC terms Level 1 consultation; and (2) following completion of the FSS, which the NRC terms Level 2 consultation.

On December 17, 2017 (ADAMS Accession No. ML17047A604), the NRC sent a Level 1 consultation letter to the EPA titled Consultation on the Decommissioning of the La Crosse Boiling Water Reactor in Genoa, Wisconsin. This letter was sent because the licensees proposed DCGLs for certain radionuclides at LACBWR exceeded the soil concentration values in Table 1 of the MOU related to the industrial use scenario. The EPA responded to the Level 1 consultation by letter dated March 13, 2018 (ADAMS Accession No. ML18303A311).

As noted in the Level 1 consultation letter to the EPA (ADAMS Accession No. ML17047A604),

the DCGLs for all three of the proposed ROC at LACBWR (Co-60, Cs-137, and Sr-90) exceed the MOU soil concentration levels for the industrial use scenario. However, the residual radioactivity at the site was lower than the proposed DCGL values because meeting the not to exceed 25 mrem/year criteria must be demonstrated using an all pathways, SOF approach.

Each individual DCGL represents a concentration level corresponding to 25 mrem/year. Thus, in applying the SOF requirement, the actual cleanup values were reduced to ensure that the potential dose from all residual radioactivity at the site from all media is less than 25 mrem/year.

In a letter dated September 3, 2021 (ADAMS Accession No. ML21235A121), the NRC informed the EPA that a Level 2 consultation is not required based on the residual radioactivity remaining at the LACBWR site at this time. Specifically, the NRC staff determined that none of the survey unit average concentrations exceeded the SOF trigger value of 1.0 when compared to Table 1 of the EPA MOU for either the industrial use or the residential use dose scenarios.

6.0 CONCLUSION

The requirements at 10 CFR 50.82(a)(11) establish the criteria to be used by the NRC for terminating all or portions of the license of a power reactor facility that has an approved LTP.

These criteria include: (1) dismantlement has been performed in accordance with the approved LTP, and (2) the final radiation survey and associated documentation demonstrate that the facility and site have met the criteria for decommissioning in 10 CFR Part 20, Subpart E.

The NRC staff has concluded that all decommissioning and dismantlement activities have been completed in the 25 survey units to be released from the LACBWR license as part of this action, and the release of the subject survey units supports the process of license termination by demonstrating that this portion of the site can be released from the 10 CFR Part 50 license. The FSS activities have confirmed that the residual radioactivity in each of the survey units meets the criteria established in the LACBWR LTP. The NRC staffs review of the LACBWR LTP determined that the proposed DCGLs would ensure that the 10 CFR Part 20, Subpart E, release criteria would be met. The NRC staffs subsequent review of the LACBWR FSSR determined that the final survey reports were consistent, and demonstrated compliance, with the LACBWR LTP. Therefore, the FSS results demonstrate that the survey areas to be released as part of this action meet the radiological criteria for unrestricted release.

Based on these considerations, the NRC staff finds that the data in the licensee FSS reports dated September 17, 2019, December 16, 2019, and January 28, 2020 (ADAMS Accession Nos. ML19261A344, ML20006D756, and ML20031C839, respectively) is adequate to provide reasonable assurance that the LACBWR Class 2 and Class 3 survey units, as well as the one Class 1 buried piping survey unit, meet the unrestricted use criteria found in 10 CFR 20.1402.

The NRC staffs findings are supported by multiple NRC inspections and ORAU confirmatory measurements that substantiated that the licensees decommissioning and FSS programs adequately assessed the radiological conditions at the site.

In addition, the NRC staff concluded that (1) the FSS activities were effectively conducted in accordance with the LACBWR LTP; (2) the applicable portions of the LACBWR FSSR contain the necessary information identified in NUREG-1757, Consolidated NMSS Decommissioning Guidance; and (3) the FSS results demonstrate that the residual radioactivity assessed meet the radiological criteria for unrestricted release identified in the NRC-approved LTP. Therefore, the NRC determines that the subject 25 survey areas from the LACBWR Possession Only License, No. DPR-45, as specified in the LaCrosseSolutions, LLC, December 14, 2021, request meet the criteria for release from the license and that these survey units shall, therefore, be released from the license.

Principal Contributors: Leah Parks, NMSS Stephen Giebel, NMSS Marlayna Doell, NMSS Kim Conway, NMSS Date: May 24, 2022

Ltr ML22122A230 NMSS/DUWP OFFICE NMSS/DUWP/RDB NMSS/DUWP/RDB NRR/EVS

/RTAB NAME MDoell MD SGiebel SG LParks LP SAnderson SA DATE May 3, 2022 May 5, 2022 May 6, 2022 May 9, 2022 OGC/GCHA OFFICE NMSS/DUWP

/AGCNRP/NLO NAME KRoach KR JMarshall JM DATE May 19, 2022 May 24, 2022