ML23310A108

Confirmatory Survey Report 2023

ML23310A108
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	11/03/2023
From:	Bailey E Oak Ridge Institute for Science & Education, Energy & Environmental Systems Div
To:	Amy Snyder Reactor Decommissioning Branch
References
RFTA 23-003, DE-SC0014664 5375-SR-01-0
Download: ML23310A108 (1)

Text

100 ORAU Way

• Oak Ridge

• TN 37830

• orise.orau.gov November 3, 2023 Ms. Amy Snyder Senior Project Manager U.S. Nuclear Regulatory Commission 11545 Rockville Pike Mail Stop A10M Rockville, MD 20852

SUBJECT:

CONFIRMATORY SURVEY ACTIVITIES

SUMMARY

AND RESULTS FOR ASSESSING THE PRESENCE OF DISCRETE RADIOACTIVE PARTICLES WITHIN SELECT SURFACE AND SUBSURFACE LAND AREAS AT THE ZION NUCLEAR POWER STATION, ZION, ILLINOIS DOCKET Nos. 50-295 AND 50-304; RFTA NO.23-003; DCN: 5375-SR-01-0

Dear Ms. Snyder:

The Oak Ridge Institute for Science and Education (ORISE) is pleased to provide the enclosed final report detailing the confirmatory survey activities summary and results performed for assessing the presence of discrete radioactive particles within select surface and subsurface land areas at the Zion Nuclear Power Station in Zion, Illinois. Comments on the draft report have been addressed in this final report.

Please feel free to contact me at Erika.Bailey@orau.org if you have any comments or concerns.

Sincerely, Erika N. Bailey Survey Projects Manager ORISE ENB:enb electronic distribution:

T. Barvitskie, NRC-HQ S. Anderson, NRC-HQ G. Chapman, NRC-HQ B. Linn, NRC-RIII K. Pinkston, NRC-HQ D. Hills, NRC-RIII D. Hagemeyer, ORISE N. Altic, ORISE File/5375

CONFIRMATORY SURVEY ACTIVITIES

SUMMARY

AND RESULTS FOR ASSESSING THE PRESENCE OF DISCRETE RADIOACTIVE PARTICLES WITHIN SELECT SURFACE AND SUBSURFACE LAND AREAS AT THE ZION NUCLEAR POWER STATION, ZION, ILLINOIS E. N. Bailey ORISE FINAL REPORT Prepared for the U.S. Nuclear Regulatory Commission NOVEMBER 2023 5375-SR-01-0 Further dissemination authorized to NRC only; other requests shall be approved by the originating facility or higher NRC programmatic authority.

ORAU provides innovative scientific and technical solutions to advance research and education, protect public health and the environment, and strengthen national security. Through specialized teams of experts, unique laboratory capabilities and access to a consortium of more than 100 major Ph.D.-granting institutions, ORAU works with federal, state, local and commercial customers to advance national priorities and serve the public interest. A 501(c) (3) nonprofit corporation and federal contractor, ORAU manages the Oak Ridge Institute for Science and Education (ORISE) for the U.S. Department of Energy (DOE). Learn more about ORAU at www.orau.org.

NOTICES The opinions expressed herein do not necessarily reflect the opinions of the sponsoring institutions of Oak Ridge Associated Universities.

This report was prepared as an account of work sponsored by the United States Government.

Neither the United States Government nor the U.S. Department of Energy, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe on privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement or recommendation, or favor by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.

Zion DRP Confirmatory Survey Report 5375-SR-01-0 CONFIRMATORY SURVEY ACTIVITIES

SUMMARY

AND RESULTS FOR ASSESSING THE PRESENCE OF DISCRETE RADIOACTIVE PARTICLES WITHIN SELECT SURFACE AND SUBSURFACE LAND AREAS AT THE ZION NUCLEAR POWER STATION, ZION, ILLINOIS FINAL REPORT Prepared by E.N. Bailey ORISE NOVEMBER 2023 Prepared for the U.S. Nuclear Regulatory Commission This document was prepared for the U.S. Nuclear Regulatory Commission (NRC) by the Oak Ridge Institute for Science and Education (ORISE) through Interagency Agreement 31310021S0033 between the NRC and the U.S. Department of Energy (DOE). ORISE is managed by Oak Ridge Associated Universities under DOE contract number DE-SC0014664.

Zion DRP Confirmatory Survey Report i

5375-SR-01-0 CONFIRMATORY SURVEY ACTIVITIES

SUMMARY

AND RESULTS FOR ASSESSING THE PRESENCE OF DISCRETE RADIOACTIVE PARTICLES WITHIN SELECT SURFACE AND SUBSURFACE LAND AREAS AT THE ZION NUCLEAR POWER STATION, ZION, ILLINOIS Prepared by:

Date:

E. N. Bailey, Survey Projects Manger ORISE Reviewed by:

Date:

N. A. Altic, CHP, Health Physicist ORISE Reviewed by:

Date:

P. H. Benton, Quality Manager ORISE Reviewed and approved for release by:

Date:

Derek Hagemeyer, Director, IEAV ORISE FINAL REPORT NOVEMBER 2023 11/3/2023 11/3/2023 11/3/2023 11/3/2023

Zion DRP Confirmatory Survey Report ii 5375-SR-01-0 CONTENTS FIGURES.......................................................................................................................................................... iv TABLES............................................................................................................................................................. iv ACRONYMS..................................................................................................................................................... v

1. INTRODUCTION....................................................................................................................................... 1

2. SITE DESCRIPTION................................................................................................................................. 2

3. DATA QUALITY OBJECTIVES............................................................................................................. 3 3.1 State the Problem.............................................................................................................................. 4 3.2 Identify the Decision/Objective..................................................................................................... 6 3.3 Identify Inputs to the Decision/Objective.................................................................................... 8 3.3.1 Radionuclides of Concern and Release Guidelines.............................................................. 9 3.4 Define the Study Boundaries......................................................................................................... 11 3.5 Develop a Decision Rule................................................................................................................ 15 3.5.1 PSQ1: Decision Rule Addressing the Presence of DRPs in Surface Soils.................... 15 3.5.2 PSQ2: Decision Rule Addressing the Presence of DRPs in Subsurface Soils............... 16 3.5.3 PSQ3: Select Class 1 Survey Units....................................................................................... 17 3.6 Specify Limits on Decision Errors............................................................................................... 17 3.6.1 Statistical Hypothesis Testing............................................................................................... 18 3.6.2 Field and Analytical MDCs................................................................................................... 19 3.7 Optimize the Design for Obtaining Data.................................................................................... 19

4. PROCEDURES.......................................................................................................................................... 19 4.1 Reference System............................................................................................................................ 19 4.2 Measurement/Sampling Locations............................................................................................... 20 4.3 Surface Scans.................................................................................................................................... 21 4.4 Investigation of Anomalies............................................................................................................ 22 4.5 Soil Sampling.................................................................................................................................... 23

5. SAMPLE ANALYSIS AND DATA INTERPRETATION............................................................... 23

6. FINDINGS AND RESULTS................................................................................................................... 24 6.1 Surface Scans and Subsurface Grid Investigations.................................................................... 24 6.2 DRP/DRO Radionuclide Total Activity..................................................................................... 25 6.3 Radionuclide Concentrations in Volumetric Samples............................................................... 25

7.

SUMMARY

AND CONCLUSIONS...................................................................................................... 30

8. REFERENCES........................................................................................................................................... 32

Zion DRP Confirmatory Survey Report iii 5375-SR-01-0 APPENDIX A: FIGURES APPENDIX B: DATA TABLES APPENDIX C: MAJOR INSTRUMENTATION APPENDIX D: SURVEY AND ANALYTICAL PROCEDURES

Zion DRP Confirmatory Survey Report iv 5375-SR-01-0 FIGURES Figure 2.1. ZNPS Overview............................................................................................................................. 3 Figure 3.1. ZNPS Routes of Concrete Debris from Turbine Building...................................................... 5 Figure 3.2. Surface Confirmatory SUs and Scan Coverage........................................................................ 12 Figure 3.3. Subsurface Confirmatory SUs and Grid IDs........................................................................... 14 Figure 4.1. VSP Inputs and Outputs for Presence/Absence Acceptance Sampling for Subsurface SUs..................................................................................................................................................................... 21 Figure 6.1. Strip Chart for Judgmental Soil Samples.................................................................................. 28 Figure 6.2. Q-Plot for Random Surface Soil Samples................................................................................ 29 TABLES Table 3.1. Independent Confirmatory Survey Decision Process................................................................ 7 Table 3.2. ZNPS Soil DCGLs and Corresponding MDCs........................................................................ 10 Table 6.1. Summary of Zion SUs Investigated............................................................................................ 24 Table 6.2. Summary of Sample Concentrations.......................................................................................... 26

Zion DRP Confirmatory Survey Report v

5375-SR-01-0 ACRONYMS AL action level CCDD clean concrete demolition debris cm centimeter(s)

Co-60 cobalt-60 cpm counts per minute Cs-134 cesium-134 Cs-137 cesium-137 DCGL derived concentration guideline level DCGLBC base case derived concentration guideline level DCGLEMC elevated measurement comparison derived concentration guideline level DCGLOp operational derived concentration guideline level DQO data quality objective DRO discrete radioactive object DRP discrete radioactive particle Exelon Exelon Generating Company FSS final status survey H-3 tritium H0 null hypothesis HA alternative hypothesis IL investigation level ISFSI independent spent fuel storage installation LTP license termination plan m/s meter per second MARSSIM Multi-Agency Radiation Survey and Site Investigation Manual MDA minimum detectable activity MDC minimum detectable concentration mrem/yr millirem per year NaI thallium-doped sodium iodide Ni-63 nickel-63 NIST National Institute of Standards and Technology NORM naturally occurring radioactive material NRC U.S. Nuclear Regulatory Commission ORAU Oak Ridge Associated Universities ORISE Oak Ridge Institute for Science and Education pCi/g picocurie per gram PSQ principal study question RA remedial action RAI request for additional information RESL Radiological and Environmental Sciences Laboratory ROC radionuclide of concern RRA radiologically restricted area SOF sum-of-fractions Sr-90 strontium-90 SU survey unit TEDE total effective dose equivalent VSP Visual Sample Plan ZNPS Zion Nuclear Power Station ZS ZionSolutions

Zion DRP Confirmatory Survey Report 1

5375-SR-01-0 CONFIRMATORY SURVEY ACTIVITIES

SUMMARY

AND RESULTS FOR ASSESSING THE PRESENCE OF DISCRETE RADIOACTIVE PARTICLES WITHIN SELECT SURFACE AND SUBSURFACE LAND AREAS AT THE ZION NUCLEAR POWER STATION, ZION, ILLINOIS

1. INTRODUCTION The Zion Nuclear Power Station (ZNPS) consisted of two reactors, Unit 1 and Unit 2, which operated commercially from 1973 to 1997 and 1974 to 1996, respectively. Cessation of nuclear power operations was certified in 1998 after both reactor units were defueled and the fuel assemblies placed in spent fuel pools. Both units were then placed in safe storage pending the commencement of site decommissioning and dismantlement. In 2010, the U.S. Nuclear Regulatory Commission (NRC) operating license was transferred from Exelon Generating Company (Exelon) to ZionSolutions, LLC (ZS) to allow the physical decommissioning process to begin in 2010.

As part of decommissioning, all above-grade structures, with minor exceptions, were demolished.

Structures below the 588-foot elevation (referenced from mean sea level), consisting of primarily exterior sub-grade walls and floors, remain. These basement structures were backfilled as part of the final site restoration. In order to demonstrate compliance with 10 Code of Federal Regulations 20.1402, ZS previously implemented final status survey (FSS) activities of remaining basement structures, along with associated embedded piping, building penetrations, and buried piping. FSS activities for the soils have also been completed by ZS. FSS methodologies are outlined in Chapter 5 of ZSs license termination plan (LTP) (ZS 2018) and methods are based on those outlined in the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) (NRC 2000).

NRC staff requested that the Oak Ridge Institute for Science and Education (ORISE) perform surface and subsurface confirmatory survey activities within select land areas of the site. The focus of these confirmatory survey activities was to assess the presence of discrete radioactive particles (DRPs) or discrete radioactive objects (DROs) in specific areas of the site identified by the NRC, including select survey units (SUs) where the licensee re-performed gamma scans utilizing DRP data quality objectives (DQOs) after FSS activities were completed in April 2021. An additional objective was to confirm the radiological status of select Class 1 FSS SUs in which the site re-performed FSS activities post April 2021. The NRC will use the confirmatory survey data for their decision making.

Zion DRP Confirmatory Survey Report 2

5375-SR-01-0 A project-specific plan was developed to support the confirmatory survey activities requested (ORISE 2023).

2. SITE DESCRIPTION The ZNPS is in Lake County, Illinois, on the easternmost portion of the city of Zion. It is approximately 64 kilometers (40 miles) north of Chicago, Illinois, and 68 kilometers (42 miles) south of Milwaukee, Wisconsin. The owner-controlled site is comprised of approximately 134 hectares (330 acres) and is situated between the northern and southern parts of Illinois Beach State Park on the western shore of Lake Michigan (EC 2015 and ZS 2018). The site and its surrounding environs are relatively flat with the elevation of the developed portion of the site at approximately 591 feet above mean sea level; for reference, the elevation of Lake Michigan - which bounds the site on the east - is approximately 577.4 feet at low water level (ZS 2018).

Major decommissioning activities at Zion are now complete, as such, all above-grade structures associated with reactor operations have been removed and the associated excavations have been backfilled. The area within the former security-restricted area fence contained the principal components of the power plant, including the two containment structures, the turbine building, auxiliary building, crib house, and waste-water treatment facility. Figure 2.1 provides recent satellite imagery depicting site conditions as of August 6, 2022. The sites FSS SU boundaries are outlined in Figure 3.2.

Zion DRP Confirmatory Survey Report 3

5375-SR-01-0 Figure 2.1. ZNPS Overview (screenshot from Google Earth)

3. DATA QUALITY OBJECTIVES The DQOs described herein are consistent with the Guidance on Systematic Planning Using the Data Quality Objectives Process (EPA 2006) and provided a formalized method for planning radiation surveys, improving survey efficiency and effectiveness, and ensuring that the type, quality, and

Zion DRP Confirmatory Survey Report 4

5375-SR-01-0 quantity of data collected were adequate for the intended decision applications. The seven steps in the DQO process were as follows:

1. State the problem

2. Identify the decision/objective

3. Identify inputs to the decision/objective

4. Define the study boundaries

5. Develop a decision rule

6. Specify limits on decision errors

7. Optimize the design for obtaining data Confirmatory survey DQOs were originally presented in ORISE 2023 and are represented here for completeness.

3.1 STATE THE PROBLEM The first step in the DQO process defined the problem that necessitated the study, identified the planning team, and examined the project budget and schedule. The planning team, project budget, and schedule are presented in ORISE 2023 and are not discussed here. Objectives of these supplemental confirmatory survey activities were to obtain independent quantitative radiological data for the NRCs use in evaluating radiological conditions at the Zion facility. The surveys focused on identifying DRPs/DROs via ORISE surveyors hand-scanning in select SUs identified by the NRC for both surface and subsurface locations while considering the technical basis outlined in Estimating Scan Minimum Detectable Activities of Discrete Radioactive Particles (ORISE 2022).

DRPs/DROs were released and distributed on land areas during cask loading operations and by atmospheric releases from containment during decommissioning activities. Transport of DRPs/DROs may have occurred due to local flooding events and site activities (e.g., land grading, vehicle traffic, and personnel transit). The sources of DRPs are summarized in two licensee condition reports (CR-2014-001074 and DR-2015-000324) and licensee responses to NRC staffs requests for additional information (RAI). A map detailing routes of vehicles transferring concrete debris, noted as clean concrete demolition debris (CCDD) on the map, from the turbine building footprint within and beyond the former radiologically restricted area (RRA) is presented in Figure 3.1. Vehicles exiting the RRA were required to pass through a truck monitor that provided screening for radioactive contamination.

Zion DRP Confirmatory Survey Report 5

5375-SR-01-0 Figure 3.1. ZNPS Routes of Concrete Debris from Turbine Building (adapted from RAI Response 1-g)

DRPs were found by the licensee when decommissioning operations were being conducted onsite, during the performance of FSS, and while performing additional gamma scans post FSS activities completed during/after April 2021. ORISE had also identified DRPs/DROs during previous confirmatory surveys. The licensee performed traditional MARSSIM-based FSS and remedial action (RA) support surveys but modified their survey methods during/after April 2021 to increase the probability of DRP identification in site locations where DRPs were found. Prior to these confirmatory site visits, DRPs were not expected at a high density within open land areas that have previously received direct radiation scans. However, the concern was that remaining DRPs may be sufficient in number to be of regulatory concern for license termination. If supplemental confirmatory survey activities do not identify DRPs/DROs, then there is increased confidence that land surfaces may be acceptable for release for unrestricted use. Alternatively, if DRPs/DROs are found during these surveys, there is an increased likelihood that a member of the public could encounter a DRP/DRO after the site is released for unrestricted use.

Zion DRP Confirmatory Survey Report 6

5375-SR-01-0 NRC consideration in the DQO process included the acceptability of finding DRPs/DROs during the supplemental surface and subsurface confirmatory surveys, taking into consideration the location and number of DRPs/DROs identified.

Supplemental confirmatory surveys were necessary to obtain updated and independent radiological data for the NRC staffs assessment of final radiological conditions at the Zion site for their safety evaluation supporting license termination. The objectives of these survey activities were to assess whether DRPs/DROs were still present at an unacceptable frequency and activity level on the surface/subsurface in select SUs. Unacceptability will be determined by the NRC.

Additionally, NRC requested that ORISE staff collect two surface soil samples in the SUs selected for 10% scan coverage and in which the site re-performed FSS activities post April 2021 for determination of residual radioactivity levels to confirm they were less than the NRC-approved decommissioning criteria. The sample locations were either judgmental based on elevated gamma levels identified during scans or random so that at least two surface sample locations were sampled within each of these survey units.

Considering the above information, the problem statement is formulated as:

Confirmatory surveys were required to provide NRC staff with independent radiological data for the Zion site. Specifically, the confirmatory survey was designed to assess the presence of DRPs/DROs in surface and subsurface soils. Additionally, the confirmatory survey provided NRC staff with information related to the residual radioactivity soil concentrations.

3.2 IDENTIFY THE DECISION/OBJECTIVE The second step in the DQO process identified the principal study questions (PSQs) and alternative actions, developed decision statements, and organized multiple decisions, as appropriate. This second step is done by specifying alternative actions that could result from a Yes response to the PSQs and combining the PSQs and alternative actions into decision statements. Three PSQs arose as a result of the problem statement introduced in Section 3.1. PSQs, alternative actions, and combined decision statements are organized based on the survey unit type (i.e., surface or subsurface) and presented in Table 3.1.

Zion DRP Confirmatory Survey Report 7

5375-SR-01-0 Table 3.1. Independent Confirmatory Survey Decision Process Principal Study Questions Alternative Actions PSQ1: Are DRPs/DROs absent in surface soils in open land areas in select SUs?

Yes:

DRPs/DROs are absent in the locations surveyed, which provides sufficient information on the likelihood that DRPs/DROs are not present in numbers of concern in surface soils in open land areas throughout the site.

Compile and document confirmatory survey data; provide independent interpretation that confirmatory survey results did not generate anomalous field or analytical data; and confirm that survey coverage is sufficient for NRC staffs decision making and regulatory action.

No:

DRPs/DROs are present in the locations surveyed. The identification of DRPs/DROs in land areas in surface soils needs to be assessed by NRC staff to determine whether it is acceptable for license termination. Compile and document confirmatory survey data; provide independent interpretation that confirmatory survey results generated anomalous field or analytical data; and confirm that survey coverage is sufficient for NRC staffs decision making and regulatory action.

PSQ2: Are DRPs/DROs absent in subsurface soils in the locations investigated?

Yes:

DRPs/DROs are absent in the locations surveyed, which provides sufficient information on the likelihood that DRPs/DROs are not present in numbers of concern in subsurface areas throughout the site. Compile and document confirmatory survey data; provide independent interpretation that confirmatory survey results did not generate anomalous field or analytical data; confirm that statistical sample population examination/assessment conditions were satisfied; and confirm that survey coverage is suffcient for NRC staffs decision making and regulatory action.

No:

DRPs/DROs are present in the locations surveyed. The identification of DRPs/DROs in land areas during these surveys needs to be assessed by NRC staff to determine whether it is acceptable for license termination. Compile and document confirmatory survey data; provide independent interpretation that confirmatory survey results generated anomalous field or analytical data; confirm that statistical sample population examination/assessment conditions is sufficient; and confirm that survey coverage is sufficient for NRC staffs decision making and regulatory action.

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5375-SR-01-0 Table 3.1. Independent Confirmatory Survey Decision Process Principal Study Questions Alternative Actions PSQ3: For select Class 1 FSS SUs in which the site re-performed FSS activities post April 2021, are residual radioactivity levels less than the NRC-approved decommissioning criteria?

Yes:

The confirmatory survey did not identify areas that exceeded the established limits. Compile and document confirmatory survey data and confirm that prior survey activities completed are sufficient for NRC staffs decision making and regulatory action.

No:

The confirmatory survey identified one or more locations with residual radioactivity concentrations exceeding the established limits. These areas were previously deemed acceptable for unrestricted use via the FSS; therefore, the subsequent surveys were not sufficient to identify locations of unacceptable contamination. Compile and document confirmatory survey data and confirm that prior survey coverage is sufficient for NRC staffs decision making and regulatory action.

Decision Statements Based on the three PSQs, the corresponding decision statements are:

Determine if the surface soils in select SUs do not contain DRPs/DROs.

Determine if the subsurface locations investigated do not contain DRPs/DROs.

Determine if unacceptable levels of residual radioactivity are present in select Class 1 FSS SUs in which the site re-performed FSS activities post April 2021.

3.3 IDENTIFY INPUTS TO THE DECISION/OBJECTIVE The third step in the DQO process identified both the information needed and the sources of this information, determined the basis for action levels, and identified sampling and analytical methods that will meet data requirements. For this effort, information inputs include the following:

• Previous licensee, NRC, and ORISE field survey data (prior scan coverage; SUs investigated by NRC/ORISE); Previous ORISE confirmatory gamma survey coverage and results are summarized in ORISE 2018, 2019, 2020a 2020b, and 2021;

• Historical site information (prior locations of DRP/DRO identification - see Figure A.1) and information on additional FSS activities performed post April 2021;

• Results from these surface and subsurface supplemental confirmatory survey activities, including in-field investigations of anomalies;

• Laboratory analysis protocols for DRP assessment (Section 5);

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5375-SR-01-0

• Soil sample analytical results generated from these supplemental confirmatory survey activities;

• Acceptability/unacceptability of remaining DRPs/DROs and future actions will be determined by NRC staff following these additional confirmatory survey activities.

3.3.1 Radionuclides of Concern and Release Guidelines DRPs/DROs Guidelines for DRPs/DROs have not been established. NRC intends to perform various assessments as part of their safety evaluation based on recent findings by ZS post April 2021 as well as by ORISE. Based on previous ORISE analytical results, there were four groups related to the origin source of particles present: (1) neutron activation of reactor corrosion products (e.g., Co-60, Ni-63, Fe-55), (2) neutron activation of the reactor bioshield (e.g., Eu-152, Eu-154, Ba-133), (3) irradiated fuel fragment (e.g., transuranic and fission products), and (4) unknown (thorium isotopes).

Derived Concentration Guideline Levels - for Residual Radioactivity The primary radionuclides of concern (ROCs) identified for ZNPS were beta-gamma emitters -

fission and activation products - resulting from reactor operations. ZNPS developed site-specific derived concentration guideline levels (DCGLs) that correspond to a residual radioactive contamination level, above background, which could result in a total effective dose equivalent (TEDE) of 25 millirem per year (mrem/yr) to an average member of the critical group. These DCGLs - defined in ZNPSs LTP as Base Case DCGLs (DCGLBC) - are radionuclide-specific and independently correspond to a TEDE of 25 mrem/yr for each source term. The initial suite of ROCS present at ZNPS was reduced based on an insignificant dose contribution from a number of radionuclides. As such, the DCGLBC was reduced to remove the dose from these insignificant radionuclides.

In order to ensure the total dose from all site-related source terms - basement structures, soils, buried piping, and groundwater - was less than the release criterion, the DCGLBC were further reduced to operational DCGLs (DCGLOp). The DCGLOp represent expected dose from prior investigations and were used for remediation and FSS/RA support survey design purposes. Base case and operational DCGLs for soil (including both surface and subsurface soil), accounting for insignificant dose contributors, are provided in Table 3.2. Note that ZS did not identify H-3 as a

Zion DRP Confirmatory Survey Report 10 5375-SR-01-0 primary ROC for soils. However, H-3 analysis was performed on 3 soil samples, as requested by NRC.

Table 3.2. ZNPS Soil DCGLsa and Corresponding MDCs (pCi/g)

ROC Surface Soil DCGL Subsurface Soil DCGL Approximate Analytical MDCsb Base Case Operational Base Case Operational Co-60 4.26 1.091 3.44 0.881

< 0.1 Cs-134 6.77 1.733 4.44 1.137

< 0.1 Cs-137 14.18 3.630 7.75 1.984

< 0.1 Ni-63 3,572.10 914.458 763.02 195.333

<2 Sr-90 12.09 3.095 1.66 0.425

<0.4 H-3

-c

-c

-c

-c

<3 aRecreated from ZS 2018 bBased on observed analytical MDCs cH-3 was not identified as primary ROC, therefore, DCGLs are not available ROC = radionuclide of concern DCGL = derived concentration guideline level pCi/g = picocuries per gram MDC = minimum detectible concentration Because each individual DCGL corresponds to the TEDE criterion, the sum-of-fractions (SOF) approach must be used to evaluate the total dose from the SU and demonstrate compliance with the dose limit. For the ORISE confirmatory samples, a SOF calculation is provided for random and judgmental soil samples but not for DRP/DRO samples. The SOF calculations were performed as follows:

SOFTOTAL =

SOFj =

=0

Cj DCGLj

=0 Eq. (3-1)

Where:

Cj is the concentration of ROC j and DCGLj is the DCGLOp or DCGLBC for ROC j.

Soil area factors are presented in Section 5.2.15, Tables 5-16 and 5-17 of the LTP (ZS 2018) and are not reproduced in this document.

Zion DRP Confirmatory Survey Report 11 5375-SR-01-0 3.4 DEFINE THE STUDY BOUNDARIES The fourth step in the DQO process defined target populations and spatial boundaries, determined the timeframe for collecting data and making decisions, addressed practical constraints, and determined the smallest subpopulations, area, volume, and time for which separate decisions must be made.

Temporal Boundaries - Confirmatory survey field work was completed in 14 days onsite during three separate weeks in the field. Surface confirmatory activities were conducted during all three weeks: June 26, July 10, and July 31, 2023. Subsurface activities were conducted during the week of July 10, 2023.

Physical Boundaries, Surface - The survey units evaluated via surface scans are presented in Figure 3.2. The SUs selected and desired percent scan coverage was determined by NRC staff. Areas targeted for the confirmatory survey included either all (100% scan coverage) or a portion (10% scan coverage) of individual SUs, and the selection of these areas was not necessarily dependent on the licensee survey unit classification but the history of where DRPs/DROs have been identified and/or transportation routes through the site. In the SUs identified with 10% surface scan coverage, ORISE surveyors performed high density scans in the vicinity of any subsurface sampling grid centroid locations with the SUs and then otherwise spread scan coverage throughout the SU to achieve an overall total of 10% coverage. The final confirmatory survey study boundaries were determined by safe access conditions during the site visits. Confirmatory survey investigations/sampling for these SUs was limited to surface soil (top 15 centimeters [cm] of soil). The independent spent fuel storage installation (ISFSI) influenced ambient radiation levels in surrounding SUs, thereby decreasing the sensitivity of direct gamma radiation surveys; gamma shine from the ISFSI was addressed by the use of sodium iodide (NaI) detector collimators constructed from lead in select SUs.

Zion DRP Confirmatory Survey Report 12 5375-SR-01-0 Figure 3.2. Surface Confirmatory SUs and Scan Coverage

Zion DRP Confirmatory Survey Report 13 5375-SR-01-0 Physical Boundaries, Subsurface - The survey units and grids evaluated (100% scan coverage) via excavations are presented in Figure 3.3. NRC staff opted for the grid cell excavations to be minimally 1 meter (m) x 1m x 1m in size. The area on the surface was enlarged as needed in order to slope the sidewalls back appropriately for safe access. However, the site equipment operators kept the excavations to no more than 1 m in depth to prevent the creation of confined spaces. The site also cut access steps/paths into each excavation and spread the spoils from the excavations in 6-inch depths for scanning. If gamma shine from the ISFSI was an issue in nearby SUs, detector collimators were used. Health and safety considerations were taken into account when performing all confirmatory survey activities. The 1-m excavation depth is noteworthy as the sites LTP committed to the removal of all structural surfaces and components to a depth of at least 0.91 m (3 feet) below grade (designated as an elevation of 588 foot above mean sea level) with a covering of at least 0.91 m of clean fill (ZS 2018). Additionally, DRPs have been previously identified in the subsurface at depths up to 0.51 m deep.

Zion DRP Confirmatory Survey Report 14 5375-SR-01-0 Figure 3.3. Subsurface Confirmatory SUs and Grid IDs

Zion DRP Confirmatory Survey Report 15 5375-SR-01-0 3.5 DEVELOP A DECISION RULE The fifth step in the DQO process specified appropriate population parameters (e.g., mean, median), confirmed action levels were above detection limits; and developed an ifthen decision rule statement. Three PSQs were introduced in Table 3.1; therefore, multiple decision rules arose. Decision rules for each PSQ are discussed below.

The overarching decision for this study was related to whether the final radiological conditions at the Zion site are suitable for release with no radiological restrictions. DQO outputs for Step 5 included specification of a survey investigation level (IL) and action level (AL). The AL served as the basis for selecting between the alternative actions for the PSQs, while the IL was the threshold for additional survey investigations.

3.5.1 PSQ1: Decision Rule Addressing the Presence of DRPs in Surface Soils The decision rule for assessment of DRPs/DROs within surface soils in select SUs were related to the presence/absence of DRPs/DROs and the corresponding analytical results for NRCs safety evaluations. Each measurement had an outcome that was either: (1) acceptable (DRP/DRO was not identified and, therefore, highly likely all detectable DRPs/DROs have been identified/removed),

(2) potentially unacceptable (DRP/DRO was identified, and analytical results required further regulatory assessment for compliance or DRPs/DROs were identified at/near boundaries of the survey area such that additional surveys were warranted to identify/remove surface DRPs/DROs located outside of this surveys boundaries). Therefore, the AL for this decision rule was the presence/absence of a DRP/DRO, either identified through field surveys and confirmed with analytical data or identification of a DRP during laboratory analysis. NRC staff were particularly interested in the total number of DRPs/DROs identified and depth of the DRPs/DROs.

Investigation of each SU involved a methodical direct gamma radiation survey using hand-held NaI detectors with collimators, as needed, at the NRC requested scan coverage. The unknown DRP/DRO distribution within the vertical soil strata precluded the implementation of a fixed IL.

For example, a DRP/DRO at a soil depth of 15 cm would yield a much smaller detector response than a DRP/DRO residing on the surface. Therefore, the gamma IL was a NaI detector response that was audibly distinguishable from localized background. Locations distinguishable from

Zion DRP Confirmatory Survey Report 16 5375-SR-01-0 background were investigated. Section 4.4 outlines additional investigation protocols if the surveyor suspected the presence of a DRP.

Based on the previous information, the decision rule is stated as:

If an unacceptable number of DRPs/DROs are not identified as a result of the confirmatory survey, and all identified DRPs/DROs are less than allowable activity limits for a specific area, then conclude that a high percentage of the SUs is acceptable; otherwise, conclude that at least some portion of the surface SUs contains DRPs. NRC will determine acceptability/unacceptability in the number of DRPs/DROs.

3.5.2 PSQ2: Decision Rule Addressing the Presence of DRPs in Subsurface Soils Because surface scanning with the NaI detector is limited to surface soil, a presence/absence sampling approach was implemented to evaluate subsurface soils. The formal statistical approach to presence/absence measurements is also known as acceptance sampling when some of the observations can be unacceptable. The presence/absence sampling approach required that all surfaces in the decision area be divided into non-overlapping, equal-size grid cells of specified size.

NRC staff opted for the grid cell excavation to be approximately 1m x 1m x 1m in size. Ultimately, 89 grid cells were then randomly selected for investigation.

Likewise, investigation of each subsurface grid cell involved a methodical direct gamma radiation survey using hand-held NaI detectors with collimators, as needed near the ISFSI. The bottom of the excavation, sidewalls, and spoils of each excavation were scanned. The surface of the grid location and where spoils were placed were scanned prior to excavation. NRC staff assisted ORISE staff with scanning the spoils laydown areas using ORISE equipment. The gamma IL was a NaI detector response that was audibly distinguishable from background. Each location distinguishable from background was investigated. Section 4.4 outlines additional investigation protocols if the surveyor suspected the presence of a DRP.

Based on the previous information, the decision rule is stated as:

If an unacceptable number of DRPs/DROs are not identified as a result of the confirmatory survey, and all identified DRPs/DROs are less than allowable activity limits for a specific area, then conclude that a high percentage of the SU is acceptable; otherwise conclude that

Zion DRP Confirmatory Survey Report 17 5375-SR-01-0 at least some portion of the subsurface SUs contains DRPs. NRC will determine acceptability/unacceptability in the number of DRPs/DROs.

One limitation is that if a particle was detected, the survey data does not provide definitive information related to the origin of the DRP.

3.5.3 PSQ3: Select Class 1 Survey Units Decisions involving select Class 1 SUs, identified as the SUs requiring 10% scan coverage in Figure 3.2, in which the site re-performed FSS activities post April 2021 were related to the identification of residual contamination above the surface soil DCGLs. As indicated in Step 1, there was overlap in the survey design addressing each PSQ. Namely, the direct radiation survey scan performed for assessing the presence of DRPs was sufficient to identify elevations in residual radioactivity that may be present.

The DCGLOp and corresponding scan survey count rate was established as the IL, which served as a trigger for a field investigation that may have included the collection of a judgmental soil sample.

The parameter of interest for assessing soils in these SUs were the individual ROC concentrations within each judgmental sample. The ALs for this assessment were the DCGLBC and the elevated measurement comparison DCGL (DCGLEMC), and the IL was the NaI detector response indicating the presence of contamination above the Operational DCGL. Upon exceedance of the IL, the surveyor performed additional investigation, which may have included the collection of a volumetric soil sample, as appropriate.

The decision rule for these select Class 1 SUs is stated as:

If the ROC concentrations of all individual judgmental soil samples are below the Operational DCGL; then conclude SUs meet the NRC-approved decommissioning criteria.

Note: If judgmental samples are not collected, random samples will be collected and assessed in the same way.

3.6 SPECIFY LIMITS ON DECISION ERRORS The sixth step in the DQO process examined the consequences of making an incorrect decision and established bounds on decision errors. Decision errors were controlled during the survey design,

Zion DRP Confirmatory Survey Report 18 5375-SR-01-0 on-site field investigations, and during the data assessment. There were two orders of control, each discussed in the following subsections.

3.6.1 Statistical Hypothesis Testing Hypothesis testing adopted a scientific approach where the survey data were used to select between the baseline condition (the null hypothesis, H0) and an alternative condition (the alternative hypothesis, HA). The null hypothesis was assumed to be true in absence of strong evidence to the contrary. How the null hypothesis, or the assumed base condition is stated, is normally based on which base condition carries the greatest risk, such as releasing a contaminated area or alternatively expending budgeted resources on investigations of potentially clean areas. Required parameter inputs for the presence/absence sampling design for the subsurface SUs were the desired percentage of the decision area that was acceptable, the confidence at which the decision area was deemed acceptable, and the size of the decision area. An additional parameter input specifying the allowable percentage of unacceptable samples was required for the acceptance-based design (i.e., subsurface SUs). The first order of control was setting the desired confidence level for which the decision was made to 95%. The desired percentage of the decision area that was acceptable was 90%. The acceptable number of DRPs identified in all subsurface grids investigated was not more than four.

These parameters resulted in 89 subsurface grids that required investigation.

The assumed base condition (referred to as the null hypothesis, H0) is stated as:

H0: At least 90% of the SUs do not contain an unacceptable number of DRPs.

If a DRP/DRO was identified above the established frequency, the null hypothesis would be rejected, and concluded that at least some portion of the decision area contained an unacceptable number of DRPs/DROs. All 89 subsurface grid cells were investigated during the confirmatory survey; therefore, a retrospective analysis of the achieved confidence and acceptable percentage of the decision area was not necessary. A formal presence/absence sampling approach was not necessary, as surface scans are sufficient to investigate the entire study boundary. Note, presence/absence decisions for surface soils are limited to the SUs that received high-density surface scans.

Zion DRP Confirmatory Survey Report 19 5375-SR-01-0 3.6.2 Field and Analytical MDCs The second order of control was to optimize the confirmatory field measurement and laboratory analytical minimum detectible concentrations (MDCs). Previous confirmatory survey scanning techniques have been sensitive enough to detect DRPs with activities less than one microcurie (with a surveyor speed of approximately 1 meter per second [m/s]). To further optimize scanning sensitivity, the surveyor speed for this confirmatory survey was reduced. Section 4.3 provides additional details regarding the surface scan procedures. The survey protocol for detecting a DRP/DRO was applied to all survey units and produced a scan MDC less than the DCGLOp.

Performance goals (MDCs) for laboratory analyses were 0.1 picocuries per gram (pCi/g) Co-60 and less than 0.1 microcurie for DRP detection. The typical analytical MDCs for volumetric soil samples provided in Table 3.2 were met.

3.7 OPTIMIZE THE DESIGN FOR OBTAINING DATA The seventh step in the DQO process was used to review DQO outputs, develop data collection design alternatives, formulate mathematical expressions for each design, select the sample size to satisfy DQOs, decide on the most resource-effective design of agreed alternatives, and document requisite details. Specific survey procedures are presented in Section 4.

4. PROCEDURES The ORISE survey team performed visual inspections, measurements, and sampling activities within the acceptable portions of SUs and grids identified in Figures 3.2 and 3.3, and areas specifically directed by NRC staff. Survey activities were conducted in accordance with the project-specific IV survey plan, the Oak Ridge Associated Universities (ORAU) Radiological and Environmental Survey Procedures Manual, and the ORAU Environmental Services and Radiation Training Quality Program Manual (ORISE 2023, ORAU 2016, ORAU 2022). Appendices C and D provide additional information regarding survey instrumentation and related processes discussed within this section.

4.1 REFERENCE SYSTEM ORISE referenced confirmatory measurement/sampling locations to global positioning system (GPS) coordinates using Illinois East state plane 1201 NAD 1983 (meters). Other prominent site

Zion DRP Confirmatory Survey Report 20 5375-SR-01-0 features were referenced, as appropriate. Measurement and sampling locations were documented on field forms and survey maps.

4.2 MEASUREMENT/SAMPLING LOCATIONS Visual Sample Plan (VSP), version 7.19, was used to calculate the required number of grid cells to be surveyed. The survey design for the acceptance sampling effort was sufficient to demonstrate that 90% of the decision area was acceptable at the 95% confidence level, with no more than 2% (4) of the grid cells containing a DRP/DRO. NRC staff were agreeable to these inputs which also optimized field survey resources. VSP planning inputs and outputs are presented in Figure 4.1. Grid cell locations are presented in Figure 3.3. If the randomly selected grid locations were generally inaccessible or impractical, the locations were adjusted based on operator judgment to an alternative location within 10 feet of the original location. Grids 88 and 89 fell on deep backfill sand piles; therefore, grids 88A and 89A were randomly generated to replace these locations. Additionally, 6 judgmental locations (90J - 95J) were selected for excavation. Grid locations 90J - 92J were selected by NRC staff in SUs where DRPs/DROs had previously been identified. The location for grid 93J was selected because numerous investigation holes were dug during performance of the ORISE gamma scans in this SU. Grid location 94J was shifted off a backfill sand pile near the original planned grid location 89 that fell on the backfill sand. The grid 95J location was selected because ORISE staff collected 6 DRPs/DROs in this general area of SU 12101.

Zion DRP Confirmatory Survey Report 21 5375-SR-01-0 Figure 4.1. VSP Inputs and Outputs for Presence/Absence Acceptance Sampling for Subsurface SUs 4.3 SURFACE SCANS Surface scans for gamma radiation were performed with Ludlum model 44-10, 5.1-centimeter by 5.1-centimeter (2-inch by 2-inch) thallium-doped NaI scintillation detectors coupled to Ludlum model 2221 ratemeter-scalers with audible indicators. Ratemeter-scalers also were coupled to hand-held GPS data-loggers to electronically record detector response concurrently with geospatial coordinates. Locations of elevated response that were audibly distinguishable from localized background levels, suggesting the presence of residual contamination, were investigated. Subsurface grid cell scan coverage was high-density 100% coverage, as the presence of a DRP in the grid served as the basis for the presence/absence data assessment.

To maximize the DRP scan sensitivity, surveys were performed with a slow scan speed (nominally 0.25 to 0.5 m/s). The detector height was no more than 7.5 cm (3 inches) above the surface being scanned. Surveyor scan minimum detectable activities (MDAs) are presented in ORISE 2022, Tables 4.1 and 4.2 for these parameters without detector collimators. Because the IL was gamma count rates that were distinguishable from localized background, surveyors used headphones to aid in

Zion DRP Confirmatory Survey Report 22 5375-SR-01-0 surveyor vigilance. The survey team gave attention to the soil type while performing surface scans, as the land areas at Zion contain multiple soil types with varying background gamma radiation levels.

Lead collimators were utilized to reduce the detector background, as needed in SUs near the ISFSI, and because the background count rate during scan surveys varied causing the scan MDC to also vary. The use of collimators assured adequate sensitivity in these high background areas. Following these DRP scan protocols in all SUs, the scan sensitivities were also sufficient in identifying volumetric hot spots although identifying DRPs/DROs was the focus of these confirmatory survey activities with the measurement goal of detecting less than one microcurie of Co-60 at the soil surface and to a depth of 15 cm (6 inches). Scan sensitivities met the goals outlined in DQO Step 6 (i.e., scan MDC less than the DCGLOp for volumetric contamination and less than one microcurie for a DRP). Appendix D provides additional information related to the scan sensitivity for volumetric contamination.

NRC staff requested the sites radiological control technicians perform contamination surveys of the equipment excavator buckets prior to beginning to dig at the next grid location.

4.4 INVESTIGATION OF ANOMALIES The general protocol for investigating anomalies with a very localized increase in detector response, which could represent the presence of a DRP/DRO, was to remove the top layer of soil (nominally up to 15 cm) and re-scan the area. A sharp increase in detector response could indicate the presence of a DRP/DRO and the surveyor continued the investigation. The total surface area of soil removed for the investigation depended on field conditions; however, a nominal area of approximately 200-300 cm2 was generally sufficient.

If a DRP/DRO was found by a surveyor during the survey activities, the surveyor looked for more DRPs/DROs in that immediate area. If no additional DRPs/DROs were found, the only action was to collect the DRP/DRO and then confirm the DRP/DRO was within the soil sample container after collection. If multiple DRPs/DROs were found in the immediate area, then each DRP/DRO was collected in its own container. If the survey team identified other anomalies, but did not identify a DRP/DRO, a judgmental soil sample was often collected, dependent on the surveyors professional judgment.

Zion DRP Confirmatory Survey Report 23 5375-SR-01-0 4.5 SOIL SAMPLING DRP/DRO samples were placed in small plastic specimen cups with screw top lids and only the amount of material necessary to contain the particle was placed in the specimen cup. Volumetric soil samples were collected using hand trowels. If necessary, a hammer drill or larger shovel was used to break up the surface soil layer. All sampling equipment was rinsed and wiped in the field after the collection of each sample to prevent cross-contamination. Prior to soil sampling, a static gamma radiation measurement was performed, then the soil was collected. Randomly generated samples were collected from a depth of 0 to 15 cm followed by a static gamma radiation measurement post sample collection. Judgmentally selected soil sample depths are noted in Table B.2. A typical soil sample was approximately 1 kilogram of soil. Soil samples were containerized in 6-millimeter-thick poly re-sealable bags (double bagged). Sample custody was maintained by ORISE staff while onsite and security seals were applied after collection. ORISE project management requested the sites certified shipper assist with packaging of the shipment(s) of DRPs/DROs to the Radiological and Environmental Sciences Laboratory (RESL).

5. SAMPLE ANALYSIS AND DATA INTERPRETATION Data collected on site were transferred to the ORISE facility for analysis and interpretation and will be archived by ORISE. Samples were transferred under chain of custody to RESL in Idaho Falls, Idaho. Sample analyses were performed in accordance with the laboratorys applicable procedures or other special instructions from ORISE and/or NRC. Volumetric samples were homogenized, and a portion of each sample was set aside for other potential future analyses before being dried and analyzed by gamma spectrometry for gamma-emitting fission and activation products.

Upon receipt of the DRP/DRO samples, RESL staff screened the samples with hand-held radiation detectors for elevated direct radiation. As part of sample preparation, the sample media was distributed into a pan for drying. After drying, sample media was scanned with hand-held detectors.

Areas of the sample exhibiting elevated direct radiation, indicating the presence of a DRP/DRO, was further isolated for additional investigation from the non-contaminated sample matrix. The material was further separated until only a small amount of material was present. Staff then opted to use tape to trap any suspect particle(s) due to their small size and highly mobile properties in the laboratory setting. NRC requested that laboratory staff obtain pictures of the DRPs/DROs/artifacts

Zion DRP Confirmatory Survey Report 24 5375-SR-01-0 prior to sample analysis and the photos were provided. Samples were first analyzed by gamma spectrometry for gamma-emitting fission and activation products. NRC selected 5 samples to also be analyzed for Ni-63 and Sr-90 including samples M0003, M0004-1, S0002, S0006, and S0009. Total sample dissolution was performed on samples M0003 and M0004-1 followed by radiochemical separation for Ni-63 and Sr-90. Additionally, H-3 analysis was performed on samples S0002, S0006, and S0009. Analytical results are reported in units of pCi/g or pCi/sample, as applicable.

6. FINDINGS AND RESULTS The results of the confirmatory survey activities are discussed in the following subsections.

6.1 SURFACE SCANS AND SUBSURFACE GRID INVESTIGATIONS Appendix A, Figures A.2 through A.3, present the gamma walkover survey data for the SUs investigated at the scan coverage indicated in Figure 3.2. Additionally, ORISE performed 10% scan coverage in SUs 10208A, B, C, and D at NRCs request. Figures A.4 through A.5, present the gamma walkover survey data for the 95 subsurface grids scanned at 100% coverage including the sidewalls of the excavations and the excavation spoils. NaI detector response for the un-collimated surveys are presented separately from scans using collimators. In a few locations, the electronic scan data were not captured because of GPS cable/equipment issues. However, the surveyor performed the planned survey coverage. The gamma walkover figures are simply a tool to provide a qualitative overview of the gamma survey results. Elevated count rates were investigated and decisions related to the presence of contamination were made in real time by the surveyor during the site visits. Table 6.1 provides a summary of the SUs investigated with further details provided in Appendix B, Table B.1.

Table 6.1. Summary of Zion SUs Investigated Total # SUs Scanned 10% 100%

Subsurface Grids Soil Samples DRPs/DROs Identified 95 28 67 95 56 12 Several subsurface grid excavations contained debris such as concrete, rebar, conduit, wood, etc.

including grids 21, 38, 63, and 77. At grid location 38, concrete debris prevented excavation to the 1-m depth so the grid was moved twice, first approximately 10 feet to the east and then another 3 feet to the north to avoid the concrete. Grids 88 and 89 fell on deep backfill sand piles therefore,

Zion DRP Confirmatory Survey Report 25 5375-SR-01-0 grids 88A and 89A were randomly generated to replace these locations. Grids 74 and 75 also fell on backfill sand piles but NRC opted to excavate these locations because the piles were not as deep.

Additionally, 6 judgmental locations (90J - 95J) were selected for excavation.

6.2 DRP/DRO RADIONUCLIDE TOTAL ACTIVITY Based on the results of the gamma scans and investigations, 11 DRP/DRO samples (M0001 -

M0011) were collected from surface soils in which 12 DRPs/DROs were isolated. DRP/DRO sample IDs are designated with an M. Two DRPs were isolated from sample M0004 in the laboratory and were analyzed separately as M0004-1 and M0004-2. Similar to previous confirmatory surveys (ORISE 2018, ORISE 2019, ORISE 2020a, ORISE 2020b, and ORISE 2021), Co-60 was the predominant radionuclide reported in the DRPs/DROs collected with a few exceptions.

Samples M0004-1, M0004-2, and M0005 exhibited higher concentrations of Eu-154 and/or Eu-152 than the Co-60 concentrations. Sample locations are shown in Figures A.6 and A.7. Table B.3 provides the sample location information including coordinates, pre-and post-sample gamma measurements, and sample depth. Table B.4 provides the analytical results for each DRP/DRO, as requested by NRC, along with the associated uncertainty. In addition to gamma spectroscopy analysis, NRC staff requested Ni-63 and Sr-90 analysis was for M0003 and M0004-1.

6.3 RADIONUCLIDE CONCENTRATIONS IN VOLUMETRIC SAMPLES Based on the results of the gamma scans and investigations, 17 judgmental soil samples (S0001 -

S0017) were collected. Additionally, 39 random surface soil samples (S0018 - S0056) were collected in select Class 1 SUs to confirm residual radioactivity concentrations were less than the NRC-approved decommissioning criteria. The site re-performed FSS activities in these Class 1 SUs post April 2021. The judgmental samples were collected to confirm the presence of naturally occurring radioactive material (NORM) or site derived ROCs that were contributing to an increase in gamma radiation levels observed by surveyors. Sample locations are shown in Figures A.6 and A.7. Table B.2 provides the sample location information including coordinates, pre-and post-sample gamma measurements, and sample depth. Analytical results for volumetric soil samples are presented in Table B.5. Table 6.2 provides a summary of the ROC concentrations for the volumetric soil samples analyzed noting not all samples have results for every ROC listed in the table. Based on current industry guidance, such as MARSSIM Section N.4, the analyte concentration is reported, regardless of whether the analyte is present. This allows for use of all data in the SOF calculation; all reported

Zion DRP Confirmatory Survey Report 26 5375-SR-01-0 concentrations greater than zero, that are not considered statistically positive at the 95% confidence interval, were included in the SOF calculations and negative values were treated as zeros.

Table 6.2. Summary of Sample Concentrations Random Soil Samples (S0018 - S0056)

Judgmental Soil Samples (S0001 - S0017)

Minimum Maximum Minimum Maximum ROC pCi/g Ag-108m

-0.01 0.01 NR NR Am-241

-0.09 0.01 NR NR Ba-133 NR NR

-0.24 0.01 Co-60

-0.01 0.01

-0.01 0.45 Cs-134

-0.09 0.01

-0.01 0.03 Cs-137 0.00 0.17

-0.01 11.70 Eu-152

-0.03 0.03

-0.03 5.14 Eu-154

-0.02 0.02

-0.02 0.25 Eu-155

-0.02 0.03 NR NR H-3 0.00 0.31 K-40 3.18 20.70 6.96 9.81 Nb-94

-0.01 0.01

-0.03 0.00 Ni-59 0.00 0.00 Ni-63 0.50 3.70 Np-237

-0.06 0.01 NR NR Ra-226 0.14 0.76 0.22 3.28 Sb-125 NR NR

-0.06 0.02 Sr-90 0.03 0.32 Th-228 0.11 0.79 0.20 1.16 Th-232 0.12 0.68 0.18 1.30 U-238 0.12 1.56 0.62 3.22 SOF Opa,b 0.00 0.05 0.00 6.02 SOF BCa,b 0.00 0.01 0.00 1.54 aOnly Co-60, Cs-134, Cs-137, Ni-63, and Sr-90 concentrations are used in SOF calculation bSamples S0001, S0006, S0007, S0009, S0014, S0015, and S0016 are subsurface samples

(>15 cm in depth) so the subsurface soil DCGLOp or DCGLBC was used in the SOF calculations.

NR = not reported

"--" = analysis not performed

Zion DRP Confirmatory Survey Report 27 5375-SR-01-0 Figure 6.1 presents strip charts, often referred to as one-dimensional scatter plots, of the judgmental soil sample concentration results. The Y-axis represents the soil sample radionuclide concentration in units of pCi/g. The X-axis of the strip chart is dimensionless. Variation in sample concentration is visually represented by the separation between data points along the Y-axis; an arbitrary separation along the x-axis allows the reader to better assess the value of individual data points. Two judgmental subsurface soil samples (S0006 and S0009) had a SOF valuebased on the subsurface DCGLOpgreater than unity. Sample S0006 exceeded because of the Cs-137 concentration and sample S0009 exceeded because of the combined Cs-137 and Sr-90 concentrations; both locations appeared to be previous sample holes and were at sample depths greater than 15 cm. These data appear as outliers in the Cs-137 and Sr-90 strip charts provided in Figure 6.1 (the highest Cs-134/137 data point in Figure 6-1 is attributed to S0006 and the second highest is attributed to S0009) The ORISE sample location S0009 appears to be in the same general area previously investigated and sampled by ZS staff during FSS activities. Although the ZS sample results for surface and subsurface samples in this area were elevated, the SOF values were less than unity noting the ZS subsurface samples were collected from a 0- to 1-m depth interval. The SOFs for ORISE samples S0006 and S0009 were also calculated using the DCGLBC and only judgmental soil sample S0006 had a SOF value greater than unity with a value of 1.54. Elevated measurement comparisons were not performed by ORISE and the results are provided for NRCs evaluation and subsequent decision making. The sizes of the elevated areas associated with samples S0006 and S0009 were estimated from the geo-referenced information generated during the gamma walkover surface scans as approximately 5 m2 and 2 m2, respectively. One other notable judgmental sample result was for sample S0002 which represents the soil remaining after particle samples M0004 and M0005 were obtained/containerized (samples M0004 and M0005 were collected from the same location). Slightly elevated concentrations of Co-60, Cs-137, Eu-152, and Eu-154 were identified and statistically positive results for H-3 and Ni-63 were reported for this sample. Eu-152 and Eu-154 results for S0002 present as potential outliers in Figure 6.1 (the highest Eu-152/154 data point in Figure 6-1 is attributed to S0002).

As indicated by Figure 6.1, the radionuclides present in these samples are primarily attributable to NORM except for soil samples S0002, S0006, and S0009 noted previously.

Zion DRP Confirmatory Survey Report 28 5375-SR-01-0 Figure 6.1. Strip Chart for Judgmental Soil Samples Figure 6.2 presents a quantile (Q) plot of the random surface soil sample concentration results. The Q-plot is a graphical tool for assessing the distribution and variability of a data set(s). The Y-axis represents the concentration in units of pCi/g and the X-axis represents the data quantiles about the median value. Values less than the median are represented in the negative quantiles; values greater than the median are represented in the positive quantiles. A normal distribution that is not skewed by outliers (i.e., a background population) will appear as a straight line, with the slope of the line subject to the degree of variability among the data population. More than one distribution, such as background plus contamination or other outliers, will appear as a step function.

Generally, the shape of the Q-plots represents analytes that are either present at or near concentrations equivalent to the MDC or present and typical background concentrations, with a few exceptions. First, the Q-plot for Cs-137 shows evidence of residual contamination by the exponential-shape of the data. Second, radionuclides representing NORM exhibit a non-normal distribution due to potential outlier data points for a single sample S0042 collected in SU 12102.

However, all random surface samples collected had a SOF valuebased on the surface DCGLOp less than unity with a maximum SOF of 0.05.

Zion DRP Confirmatory Survey Report 29 5375-SR-01-0 Figure 6.2. Q-Plot for Random Surface Soil Samples

Zion DRP Confirmatory Survey Report 30 5375-SR-01-0

7.

SUMMARY

AND CONCLUSIONS Confirmatory survey field work was completed in 14 days onsite during three separate weeks in the field. Surface confirmatory activities were conducted during all three weeks: June 26, July 10, and July 31, 2023. Subsurface activities were conducted during the week of July 10, 2023. The focus of these confirmatory survey activities was to assess the presence of DRPs/DROs in specific areas of the site identified by NRC, including select SUs where the licensee re-performed gamma scans utilizing DRP DQOs post April 2021. An additional objective was to confirm the radiological status of select Class 1 FSS SUs, in which the site re-performed FSS activities post April 2021.

Confirmatory survey activities consisted of gamma scans of surface soil and of 95 subsurface grid excavations/spoils and the collection of judgmental and random soil samples.

Based on the gamma scans and subsequent investigations, 11 DRP/DRO samples were collected from surface soils in which 12 DRPs/DROs were isolated in the laboratory. Similar to previous confirmatory surveys (ORISE 2018, ORISE 2019, ORISE 2020a, ORISE 2020b, and ORISE 2021),

Co-60 was the predominant radionuclide concentration reported associated with the DRPs/DROs collected with a few exceptions. Samples M0004-1, M0004-2, and M0005 exhibited higher concentrations of Eu-154 and/or Eu-152 than the Co-60 concentrations. No DRPs/DROs were identified by ORISE in the select Class 1 SUs requiring 10% scan coverage or in the 95 subsurface grid excavations/spoils.

Seventeen judgmental soil samples were collected. The judgmental samples were collected to either confirm the presence of NORM or site derived ROCs that were contributing to an increase in gamma radiation levels observed by surveyors. Two judgmental soil samples had a SOF value based on the DCGLOpgreater than unity. One sample exceeded because of the Cs-137 concentration and the other sample exceeded because of the combined Cs-137 and Sr-90 concentrations; both locations appeared to be previous sample holes and were at sample depths greater than 15 cm. The SOFs were also calculated using the DCGLBC and only 1 of the samples had a SOF value greater than unity with a value of 1.54. One other notable judgmental sample result was the soil collected after 2 DRPs/DROs at this location were containerized. The sample exhibited slightly elevated concentrations of Co-60, Cs-137, Eu-152, and Eu-154 were identified and

Zion DRP Confirmatory Survey Report 31 5375-SR-01-0 statistically positive results for H-3 and Ni-63 were reported. The radionuclides present in the remaining judgmental samples were primarily attributable to NORM.

Additionally, 39 random surface soil samples were collected in the select Class 1 SUs so that at least two surface sample locations were sampled within each of these SUs. All random surface samples collected had a SOF valuebased on the DCGLOpless than unity with a maximum SOF of 0.05.

In summary, the problem statement was that supplemental confirmatory surveys were necessary to obtain updated and independent radiological data for the NRC staffs assessment of final radiological conditions at the Zion site for their safety evaluation supporting license termination.

The objectives of these survey activities were to assess whether DRPs/DROs were still present at an unacceptable frequency and activity level on the surface/subsurface in select SUs. NRC will determine acceptability/unacceptability in the number of DRPs/DROs. Confirmatory survey results, herein, are provided to NRC staff for their evaluation and subsequent decision making.

Zion DRP Confirmatory Survey Report 32 5375-SR-01-0

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EPA 2006. Guidance on Systematic Planning Using the Data Quality Objectives Process. EPA QA/G-4.

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NRC 2000. Multi-Agency Radiation Site Survey and Investigation Manual (MARSSIM), Revision 1. DOE/EH-0624, Rev. 1. U.S. Department of Energy. Washington, D.C. August 2000.

ORAU 2016. ORAU Radiological and Environmental Survey Procedures Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. November 10.

ORAU 2020. ORAU Health and Safety Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee.

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ORAU 2022. ORAU Environmental Services and Radiation Training Quality Program Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. September 8.

ORISE 2018. Independent Confirmatory Survey Summary and Results for the Containment and Auxiliary Buildings at the Zion Nuclear Power Station, Zion, Illinois. DCN: 5271-SR-03-0. Oak Ridge Associated Universities. Oak Ridge, Tennessee. October 9.

ORISE 2019. Independent Confirmatory Survey Summary And Results For The Waste Water Treatment Facility And Select Land Areas At The Zion Nuclear Power Station, Zion, Illinois. DCN: 5271-SR-06-0. Oak Ridge Associated Universities. Oak Ridge, Tennessee. February 7.

ORISE 2020a. Independent Confirmatory Survey Summary And Results For The Subsurface Soils Associated With The Sacrificial Barrier At The Zion Nuclear Power Station, Zion, Illinois. DCN: 5271-SR-07-0. Oak Ridge Associated Universities. Oak Ridge, Tennessee. January 31.

ORISE 2020b. Independent Confirmatory Survey Summary And Results For the Remaining Land Areas at the Zion Nuclear Power Station, Zion, Illinois. DCN: 5271-SR-08-0. Oak Ridge Associated Universities. Oak Ridge, Tennessee. April 24.

ORISE 2021. Independent Confirmatory Survey Summary and Results Assessing the Presence of Residual Radioactivity and Radioactive Particles Within Select Land Areas at The Zion Nuclear Power Station, Zion, Illinois. DCN: 5271-SR-09-0.Oak Ridge Associated Universities. Oak Ridge, Tennessee. September 3.

ORISE 2022. Estimating Scan Minimum Detectable Activities of Discrete Radioactive Particles. Oak Ridge Associated Universities. Oak Ridge, Tennessee. October 31.

ORISE 2023. Project-Specific Plan for Confirmatory Activities Assessing the Presence of Residual Radioactivity and Radioactive Particles Within Select Surface and Subsurface Land Areas at The Zion Nuclear Power Station, Zion, Illinois. DCN: 5375-PL-01-0. Oak Ridge Associated Universities. Oak Ridge, Tennessee. June 23.

ZS 2018. Zion Station Restoration Project License Termination Plan, Rev. 2. ZionSolutions, LLC. Chicago, Illinois. February 7.

Zion DRP Confirmatory Survey Report 5375-SR-01-0 APPENDIX A: FIGURES

Zion DRP Confirmatory Survey Report A-1 5375-SR-01-0 Figure A.1. FSS Units and Locations of Previously Identified DRPs

Zion DRP Confirmatory Survey Report A-2 5375-SR-01-0 Figure A.2. Gamma Walkover for Surface Soils, Without Using Collimator

Zion DRP Confirmatory Survey Report A-3 5375-SR-01-0 Figure A.3. Gamma Walkover for Surface Soils, Using Collimator

Zion DRP Confirmatory Survey Report A-4 5375-SR-01-0 Figure A.4. Gamma Walkover for Subsurface Grids, Without Using Collimator

Zion DRP Confirmatory Survey Report A-5 5375-SR-01-0 Figure A.5. Gamma Walkover for Subsurface Soils, Using Collimator

Zion DRP Confirmatory Survey Report A-6 5375-SR-01-0 Figure A.6. Sample Locations, Northern SUs

Zion DRP Confirmatory Survey Report A-7 5375-SR-01-0 Figure A.7. Sample Locations, Southern SUs

Zion DRP Confirmatory Survey Report 5375-SR-01-0 APPENDIX B: DATA TABLES

Zion DRP Confirmatory Survey Report B-1 5375-SR-01-0 Table B.1. Zion SUs Investigated SU Surface Scan Coverage

(%)a Collimator Used?

Subsurface Grid(s)

Sample(s)

Notes on Judgmental Samples 12101 100 No 81, 95J 5375M0001, 5375M0004-1, 5375M0004-2, 5375M0005, 5375M0006, 5375M0007, 5375S0002 Sample S0002 represents the soil remaining after particle samples M0004 and M0005 were obtained/containerized.

12102 10 No 69, 76, 77 5375S0013, 5375S0042 Sample S0013 was collected from grid excavation 77. It was a thin layer of material that was darker in color. Sample was collected at 15-cm depth.

12103 10 No 5375S0040, 5375S0041 12104 10 No 71, 72 5375S0036, 5375S0037 12105 10 No 65, 66 5375S0034, 5375S0035 12106 10 No 59, 60, 61 5375S0032, 5375S0033 12107 10 No 53, 54, 55 5375S0030, 5375S0031 12108 10 No 46, 47 5375S0028, 5375S0029 12109 100 No 39, 40, 45 12110 100 No 38 12111 100 No 28, 33, 34 12112 10 No 5375S0007, 5375S0008, 5375S0009 These 3 samples were collected at locations with elevated gamma levels that were flagged during scans. Samples S0007 and S0009 appeared to be previous sample holes.

Zion DRP Confirmatory Survey Report B-2 5375-SR-01-0 Table B.1. Zion SUs Investigated SU Surface Scan Coverage

(%)a Collimator Used?

Subsurface Grid(s)

Sample(s)

Notes on Judgmental Samples 12113 10 No 5375S0001, 5375S0010 These 2 samples were collected at locations with elevated gamma levels that were flagged during scans.

10201 A 100 No 10201 B 100 No 10201 C 10 No 94J 5375S0053, 5375S0054 10201 D 10 No 82, 86 5375S0051, 5375S0052 10202 A 100 No 10202 B 100 No 10202 C 10 No 87 5375S0055, 5375S0056 10202 D 10 No 84, 85 5375S0049, 5375S0050 10203 A 100 No 10203 B 100 No 10203 C 100 No 10203 D 100 No 10203 E 100 No 10203 F 100 No 10204 A 100 No 10204 B 100 No 10204 C 100 No 10204 D 100 No 5375M0010 10206 A 100 No 10206 B 100 No 10206 C 100 No 10206 D 100 No

Zion DRP Confirmatory Survey Report B-3 5375-SR-01-0 Table B.1. Zion SUs Investigated SU Surface Scan Coverage

(%)a Collimator Used?

Subsurface Grid(s)

Sample(s)

Notes on Judgmental Samples 10206 E 100 No 10207 A 100 Yes, in southern half of SU 92J 10207 B 100 Yes, in southern half of SU 91J, 92J 10207 C 100 Yes, in southern half of SU 10207 D 100 Yes, in southern half of SU 10207 E 100 Yes, in southern half of SU 10208 A 10 Yes 10208 B 10 Yes 10208 C 10 Yes 10208 D 10 Yes 10209 A 100 Yes 8, 14 5375S0011 Sample was collected because surveyor flagged a location during scans. Nothing notable discovered during sample collection.

10209 B 100 Yes 3, 9, 15, 89A 10209 C 100 Yes 4, 10 10209 D 100 Yes 16 10209 E 100 Yes 5, 11, 17 5375M0009

Zion DRP Confirmatory Survey Report B-4 5375-SR-01-0 Table B.1. Zion SUs Investigated SU Surface Scan Coverage

(%)a Collimator Used?

Subsurface Grid(s)

Sample(s)

Notes on Judgmental Samples 10210 A 100 Yes 6

10210 B 100 Yes 1, 7, 12, 18 10210 C 100 No 2, 7, 13 10214 B 100 No 10214 C 100 No 10214 D 100 No 10214 E 100 No 10214 F 100 No 10220 A 100 Yes 5375M0008 10220 F 100 Yes 10220 G 100 Yes 10220 H 100 Yes 10220 I 100 Yes 5375S0017 Sample was collected at location with elevated gamma levels.

Sample was an odd material described as possibly crushed up asphalt but also sand-like. Six other locations were investigated in this SU that turned out to be the same material.

10220 J 100 Yes 10221 A 10 Yes 5375S0018, 5375S0019 10221 B 10 Yes 5375S0020, 5375S0021 10221 C 10 Yes 5375S0022, 5375S0023 10221 D 100 Yes 90J 10221 E 100 Yes 5375M0011 10221 F 100 Yes

Zion DRP Confirmatory Survey Report B-5 5375-SR-01-0 Table B.1. Zion SUs Investigated SU Surface Scan Coverage

(%)a Collimator Used?

Subsurface Grid(s)

Sample(s)

Notes on Judgmental Samples 10221 G 100 Yes 10221 H 100 Yes 12201 A 100 No 93J 12201 B 100 No 12201 C 10 No 73, 78, 83 5375S0047, 5375S0048 12201 D 10 No 74, 79 5375S0045, 5375S0046 12201 E 10 No 75, 80 5375S0043, 5375S0044 12202 A 100 No 58, 64, 70 5375S0014 Sample was collected from grid excavation 64. The soil was a darker clay-like layer. Sample was collected at 1-meter depth.

12202 B 100 No 52 12202 C 100 No 31, 37 12202 D 100 Yes 27, 32 12202 E 100 Yes 20, 25, 26 5375S0015 Sample was collected from grid excavation 26. The soil was a darker clay-like layer. Sample was collected at >15 cm-depth.

12202 F 100 Yes 21, 22, 23 12203 A 10 No 29 5375S0016, 5375S0026, 5375S0027 Sample was collected from grid excavation 29. The soil was a darker clay-like layer. Sample was collected at >15-cm depth.

Zion DRP Confirmatory Survey Report B-6 5375-SR-01-0 Table B.1. Zion SUs Investigated SU Surface Scan Coverage

(%)a Collimator Used?

Subsurface Grid(s)

Sample(s)

Notes on Judgmental Samples 12203 B 10 No 19, 24, 30 5375S0012, 5375S0025 Sample was collected at a location with elevated gamma levels that was flagged during scans. The southern sections of SUs 12203A and 12203B exhibited elevated gamma levels.

12203 C 10 No 5375S0003, 5375S0024 Sample S0003 was collected at a location with elevated gamma levels that was flagged during scans.

12203 D 10 No 5375S0004, 5375S0005 These 2 samples were collected at locations with elevated gamma levels that were flagged during scans.

12204 A 100 No 12204 B 100 No 50, 51 12204 C 100 No 43, 44, 88A 5375S0006 Sample was collected at a location with elevated gamma levels that was flagged during scans.

Location appeared to be previous sample hole.

12205 A 10 No 63, 67, 68 5375S0038, 5375S0039 12205 B 100 No 57, 62 12205 C 100 No 48, 49, 56 12205 D 100 No 41, 42 12205 E 100 No 35, 36 5375M0002, 5375M0003 aSubsurface grids were scanned at 100% coverage, even if the SU surface scan coverage was 10%.

Zion DRP Confirmatory Survey Report B-9 5375-SR-01-0 Table B.2. Zion Soil Sample Location Information Sample ID SU Easting Northing Collimator Used?

Sample Type Pre-Sample Meas.

Post Sample Meas.

Approx.

Sample Depth (cm)

(meters)

(cpm)

(cpm) 5375S0001 12113 343744 641685 No Judgmental 8,000 9,689 20-25 5375S0002 12101 343772 641885 No Judgmental NR NR 0-15 5375S0003 12203 C 343735 641649 No Judgmental 9,000 12,090 15 5375S0004 12203 D 343742 641649 No Judgmental 8,500 12,296 15 5375S0005 12203 D 343744 641654 No Judgmental 8,500 9,906 15 5375S0006 12204 C 343788 641709 No Judgmental 17,452 21,017

>15 5375S0007 12112 343787 641698 No Judgmental 15,497 16,540 25-30 5375S0008 12112 343785 641700 No Judgmental 12,021 12,463 15 5375S0009 12112 343769 641696 No Judgmental 8,933 8,793 20-25 5375S0010 12113 343746 641682 No Judgmental 10,270 10,729 15 5375S0011 10209 A 343534 641592 No Judgmental 12,322 12,350 0-15 5375S0012 12203 B 343679 641617 No Judgmental 8,997 10,989 0-15 5375S0013 12102 343770 641856 No Judgmental 9,379 10,258 15 5375S0014 12202 A 343597 641829 No Judgmental 13,094 14,250 100 5375S0015 12202 E 343567 641668 Yes Judgmental 4,923 5,480

>15 5375S0016 12203 A 343661 641666 No Judgmental 12,699 14,188

>15 5375S0017 10220 I 343599 641453 Yes Judgmental 4,875 4,951 0-15 5375S0018 10221 A 343530 641558 Yes Random 2,362 2,510 0-15 5375S0019 10221 A 343524 641545 Yes Random 2,835 2,512 0-15 5375S0020 10221 B 343536 641527 Yes Random 2,003 1,858 0-15 5375S0021 10221 B 343561 641549 Yes Random 1,790 1,634 0-15 5375S0022 10221 C 343574 641543 Yes Random 1,873 2,066 0-15 5375S0023 10221 C 343583 641523 Yes Random 2,444 2,763 0-15 5375S0024 12203 C 343718 641631 Yes Random 2,356 2,367 0-15 5375S0025 12203 B 343708 641669 No Random 4,616 4,915 0-15 5375S0026 12203 A 343673 641660 No Random 5,132 5,696 0-15 5375S0027 12203 A 343662 641683 No Random 5,232 4,960 0-15 5375S0028 12108 343670 641756 No Random 5,240 5,724 0-15 5375S0029 12108 343630 641747 No Random 5,257 5,797 0-15 5375S0030 12107 343609 641773 No Random 5,179 5,698 0-15 5375S0031 12107 343642 641780 No Random 5,258 5,834 0-15 5375S0032 12106 343630 641798 No Random 5,395 6,114 0-15 5375S0033 12106 343608 641806 No Random 5,766 7,814 0-15 5375S0034 12105 343602 641829 No Random 5,113 5,834 0-15 5375S0035 12105 343668 641816 No Random 4,933 5,829 0-15 5375S0036 12104 343666 641847 No Random 4,878 5,668 0-15

Zion DRP Confirmatory Survey Report B-10 5375-SR-01-0 Table B.2. Zion Soil Sample Location Information Sample ID SU Easting Northing Collimator Used?

Sample Type Pre-Sample Meas.

Post Sample Meas.

Approx.

Sample Depth (cm)

(meters)

(cpm)

(cpm) 5375S0037 12104 343688 641838 No Random 5,074 5,949 0-15 5375S0038 12205 A 343696 641827 No Random 4,972 5,750 0-15 5375S0039 12205 A 343736 641811 No Random 5,256 5,466 0-15 5375S0040 12103 343776 641824 No Random 6,608 9,086 0-15 5375S0041 12103 343794 641809 No Random 5,135 5,916 0-15 5375S0042 12102 343796 641841 No Random 8,835 11,646 0-15 5375S0043 12201 E 343721 641851 No Random 4,950 5,528 0-15 5375S0044 12201 E 343756 641892 No Random 4,431 5,070 0-15 5375S0045 12201 D 343731 641888 No Random 5,508 5,981 0-15 5375S0046 12201 D 343718 641880 No Random 5,563 5,954 0-15 5375S0047 12201 C 343682 641861 No Random 5,078 5,442 0-15 5375S0048 12201 C 343692 641902 No Random 5,155 5,920 0-15 5375S0049 10202 D 343739 641911 No Random 5,001 6,767 0-15 5375S0050 10202 D 343772 641910 No Random 4,616 5,437 0-15 5375S0051 10201 D 343782 641916 No Random 4,347 5,172 0-15 5375S0052 10201 D 343816 641897 No Random 3,437 4,255 0-15 5375S0053 10201 C 343799 641914 No Random 4,403 5,637 0-15 5375S0054 10201 C 343826 641929 No Random 2,953 2,738 0-15 5375S0055 10202 C 343770 641951 No Random 5,071 5,431 0-15 5375S0056 10202 C 343732 641940 No Random 4,569 5,114 0-15 SU = survey unit cpm = counts per minute cm = centimeter NR = not recorded

Zion DRP Confirmatory Survey Report B-11 5375-SR-01-0 Table B.3. Zion DRP/DRO Sample Location Information Sample ID SU Easting Northing Collimator Used?

Sample Type Pre-Sample Meas.

Post Sample Meas.

Approx.

Sample Depth (cm)

(meters)

(cpm)

(cpm) 5375M0001 12101 343762 641883 No Judgmental NR NR NR 5375M0002 12205E 343681 641688 No Judgmental 16,572 5,883 25 5375M0003 12205E 343683 641684 No Judgmental 11,509 5,565 15 5375M0004 12101 343772 641885 No Judgmental NR NR NR 5375M0005 12101 343772 641885 No Judgmental NR NR NR 5375M0006 12101 343794 641878 No Judgmental NR NR NR 5375M0007 12101 343777 641886 No Judgmental NR NR NR 5375M0008 10220A 343518 641471 Yes Judgmental 12,714 1,342 8

5375M0009 10209E 343620 641622 Yes Judgmental 8,500 NR NR 5375M0010 10204D 343590 641945 No Judgmental 7,400 NR NR 5375M0011 10221E 343647 641520 Yes Judgmental 7,100 NR 8

SU = survey unit cpm = counts per minute cm = centimeter NR = not recorded DRP/DRO = discrete radioactive particle/discrete radioactive object

Zion DRP Confirmatory Survey Report B-12 5375-SR-01-0 Table B.4. DRO/DRP Sample Concentrations (pCi/sample)

Misc. Sample ID 5375M0001 5375M0002 5375M0003 5375M0004-1 5375M0004-2 5375M0005 SU 12101 SU 12205E SU 12205E SU 12101 SU 12101 SU 12101 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ba-133 100.0 8.6 Co-60 53,100 2,380 82,100 3,660 118,000 6,000 570 59 972 74 3,040 137 Cs-137 18.1 4.9 24 11 Eu-152 4,646 424 15,500 2,320 60,600 3,860 Eu-154 291 97 1,050 137 4,370 238 Eu-155 9

24 Nb-94 61.0 8.0 Ni-59

-34,955 99,136 23.2 5.8 Ni-63 517,511 108,060 69.3 14.8 Sr-90 2.40 0.80 1.3 0.8 aResults that are considered statistically positive are bolded.

bUncertainties are based on total propagated uncertainties at the 95% confidence level. 2 sigma uncertainty is presented.

Table B.4. DRO/DRP Sample Concentrations (pCi/sample), Cont.

Misc. Sample ID 5375M0006 5375M0007 5375M0008 5375M0009 5375M0010 5375M0011 SU 12101 SU 12101 SU 10220A SU 10209E SU 10204D SU 10221E Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Co-60 383,000 17,100 284,000 12,680 53,200 2,380 17,000 760 14,200 642.00 124,000 5,520 Cs-137 143 35 25 12 aResults that are considered statistically positive are bolded.

bUncertainties are based on total propagated uncertainties at the 95% confidence level. 2 sigma uncertainty is presented.

Zion DRP Confirmatory Survey Report B-13 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g)

Soil Sample ID 5375S0001 5375S0002 5375S0003 5375S0004 5375S0005 5375S0006 5375S0007 5375S0008 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Am-241 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Ba-133 0.004 0.009

-0.061 0.069

-0.2 1.1

-0.002 0.015

-0.002 0.012

-0.016 0.052

-0.018 0.028

-0.001 0.013 Co-60

-0.002 0.003 0.446 0.022 0.005 0.007 0.004 0.004 0.011 0.015 0.027 0.005

-0.006 0.011 0.006 0.008 Cs-134

-0.002 0.011

-0.010 0.078 0.006 0.007

-0.002 0.011

-0.002 0.010

-0.001 0.010

-0.003 0.024

-0.001 0.003 Cs-137 0.001 0.003 1.200 0.055 0.005 0.002

-0.001 0.005 0.002 0.003 11.70 0.53

-0.002 0.011 0.211 0.013 Eu-152 0.005 0.005 5.14 0.34

-0.004 0.026

-0.005 0.011

-0.003 0.010

-0.008 0.030

-0.013 0.020 0.004 0.017 Eu-154

-0.001 0.011 0.254 0.020

-0.02 0.12

-0.005 0.016

-0.007 0.011

-0.004 0.011 NR NR 0.005 0.026 Eu-155 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR H-3 0.312 0.016 2.00E-03 4.00E-03 K-40 NR NR 6.960 0.464 NR NR NR NR NR NR 8.590 0.454 NR NR NR NR Nb-94 0.001 0.002

-0.026 0.063

-0.017 0.050 0.003 0.011 0.002 0.005 0.000 0.002

-0.005 0.007 0.004 0.005 Ni-59 0

12 0.00E+00 1.60E+01 Ni-63 2.60 0.60 3.7 6.00E-01 Np-237 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Ra-226 0.750 0.032 0.222 0.016 0.723 0.021 0.730 0.035 0.724 0.048 0.594 0.030 0.761 0.057 0.617 0.038 Sb-125 0.002 0.006 0.001 0.002 0.009 0.014 0.005 0.012

-0.004 0.006

-0.018 0.027

-0.009 0.030

-0.004 0.017 Sr-90 0.22 0.32 0.03 0.32 Th-228 0.514 0.022 0.198 0.014 NR NR 0.675 0.029 0.644 0.026 0.321 0.019 0.66 0.22 0.441 0.029 Th-232 0.549 0.040 0.175 0.022 0.705 0.069 0.681 0.042 0.721 0.042 0.362 0.032 0.652 0.053 0.423 0.038 U-238 1.340 0.069 0.623 0.062 1.690 0.074 0.785 0.084 0.90 0.12 0.82 0.23 1.16 0.12 1.230 0.098 SOF Opc,d 0.0003 0.81 0.01 0.004 0.01 6.02 0.00 0.06 SOF BCc,d 0.0001 0.21 0.002 0.001 0.003 1.54 0.00 0.02

Zion DRP Confirmatory Survey Report B-14 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g), Cont.

Soil Sample ID 5375S0009 5375S0010 5375S0011 5375S0012 5375S0013 5375S0014 5375S0015 5375S0016 5375S0017 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Am-241 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Ba-133

-0.006 0.007

-0.011 0.013

-0.034 0.041

-0.018 0.019 0.009 0.041

-0.018 0.047

-0.027 0.037

-0.025 0.052

-0.016 0.051 Co-60 0.004 0.012 0.003 0.005

-0.002 0.011 0.004 0.017

-0.003 0.004 0.007 0.025

-0.006 0.013

-0.001 0.007

-0.003 0.012 Cs-134

-0.004 0.008

-0.006 0.008

-0.003 0.023

-0.015 0.016

-0.008 0.015 0.028 0.039 0.006 0.014

-0.011 0.013

-0.012 0.094 Cs-137 1.610 0.037

-0.005 0.007

-0.005 0.005 0.002 0.012 0.014 0.005

-0.005 0.011 0.001 0.003 0.002 0.007

-0.003 0.013 Eu-152

-0.026 0.030

-0.010 0.019

-0.002 0.016

-0.009 0.018

-0.023 0.030

-0.005 0.032 0.027 0.050

-0.007 0.023

-0.013 0.025 Eu-154 0.008 0.020

-0.024 0.025

-0.009 0.023

-0.021 0.026

-0.018 0.024

-0.005 0.015

-0.010 0.044 0.005 0.023 0.014 0.028 Eu-155 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR H-3 0.002 0.004 K-40 9.81 0.64 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Nb-94

-0.005 0.005 0.002 0.006

-0.001 0.006 0.001 0.007

-0.004 0.007

-0.002 0.008

-0.003 0.009 0.001 0.006

-0.006 0.010 Ni-59 0

22 Ni-63 0.5 0.4 Np-237 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Ra-226 0.269 0.018 0.698 0.042 0.648 0.085 0.562 0.039 0.612 0.032 0.872 0.039 0.787 0.052 0.390 0.053 3.28 0.15 Sb-125

-0.008 0.020

-0.002 0.017 0.003 0.009 0.006 0.029 0.009 0.014

-0.060 0.064 0.019 0.027

-0.003 0.017

-0.030 0.051 Sr-90 0.32 0.32 Th-228 0.273 0.014 0.657 0.046 0.660 0.033 0.567 0.031 0.689 0.033 0.657 0.043 0.567 0.038 0.394 0.043 1.160 0.055 Th-232 0.231 0.023 0.652 0.049 0.665 0.040 0.543 0.043 0.628 0.054 0.64 0.15 0.493 0.048 0.334 0.094 1.300 0.084 U-238 0.993 0.085 1.15 0.12 0.84 0.37 0.93 0.15 1.02 0.12 0.90 0.46 1.15 0.12 1.24 0.12 3.22 0.25 SOF Opc,d 1.57 0.003 0.00 0.005 0.004 0.03 0.01 0.0008 0.00 SOF BCc,d 0.40 0.001 0.00 0.001 0.001 0.01 0.00 0.00 0.00

Zion DRP Confirmatory Survey Report B-15 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g), Cont.

Soil Sample ID 5375S0018 5375S0019 5375S0020 5375S0021 5375S0022 5375S0023 5375S0024 5375S0025 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m

-0.001 0.004

-0.001 0.007 0.002 0.004 0.002 0.003

-0.002 0.011

-0.002 0.008

-0.001 0.006

-0.002 0.008 Am-241

-0.020 0.051

-0.008 0.073

-0.017 0.071

-0.09 0.42

-0.008 0.016

-0.07 0.15

-0.011 0.063

-0.004 0.008 Ba-133 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Co-60 0.003 0.003

-0.005 0.015

-0.006 0.017

-0.001 0.004 0.009 0.022 0.010 0.012 0.002 0.007 0.001 0.007 Cs-134

-0.009 0.010 0.006 0.011 0.001 0.013

-0.005 0.008

-0.011 0.017 0.004 0.005

-0.009 0.012

-0.009 0.011 Cs-137 0.008 0.007 0.172 0.029 0.014 0.005

-0.001 0.006 0.017 0.017 0.084 0.008 0.019 0.005 0.009 0.004 Eu-152

-0.014 0.025

-0.014 0.019

-0.003 0.021

-0.005 0.011

-0.014 0.025

-0.012 0.025

-0.014 0.028 0.003 0.006 Eu-154

-0.004 0.015

-0.012 0.032

-0.009 0.026

-0.010 0.019 0.016 0.033

-0.006 0.026

-0.014 0.017

-0.017 0.020 Eu-155 0.003 0.019 0.009 0.031 0.014 0.021

-0.010 0.024 0.004 0.020 0.005 0.019

-0.020 0.028 0.001 0.012 H-3 K-40 8.85 0.59 10.60 0.80 5.57 0.51 5.94 0.34 10.60 0.86 10.30 0.72 9.54 0.70 7.49 0.53 Nb-94 0.001 0.005

-0.004 0.008 0.003 0.004

-0.003 0.005 0.009 0.010 0.001 0.004

-0.006 0.006

-0.002 0.005 Ni-59 Ni-63 Np-237

-0.003 0.012 0.013 0.026

-0.002 0.012

-0.003 0.009 0.005 0.014

-0.002 0.014 0.009 0.023 0.008 0.010 Ra-226 0.303 0.037 0.318 0.021 0.154 0.022 0.136 0.013 0.338 0.060 0.359 0.027 0.286 0.020 0.234 0.039 Sb-125 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Sr-90 Th-228 0.300 0.029 0.322 0.050 0.196 0.016 0.242 0.015 0.30 0.22 0.314 0.023 0.311 0.017 0.200 0.014 Th-232 0.271 0.069 0.260 0.030 0.189 0.089 0.251 0.029 0.319 0.042 0.339 0.038 0.282 0.076 0.202 0.032 U-238 0.982 0.080 1.05 0.11 0.20 0.12 0.296 0.087 0.482 0.093 0.842 0.086 0.910 0.094 0.89 1.07 SOF Opc,d 0.005 0.05 0.005 0.00 0.01 0.03 0.01 0.003 SOF BCc,d 0.001 0.013 0.001 0.00 0.003 0.01 0.002 0.001

Zion DRP Confirmatory Survey Report B-16 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g), Cont.

Soil Sample ID 5375S0026 5375S0027 5375S0028 5375S0029 5375S0030 5375S0031 5375S0032 5375S0033 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m

-0.001 0.003

-0.002 0.007

-0.001 0.009

-0.001 0.004

-0.002 0.008

-0.001 0.005 0.002 0.003

-0.002 0.007 Am-241 0.004 0.015 0.003 0.010

-0.008 0.011

-0.008 0.028

-0.007 0.011

-0.025 0.058

-0.019 0.060

-0.027 0.070 Ba-133 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Co-60

-0.001 0.004 0.003 0.009

-0.001 0.009

-0.003 0.004

-0.001 0.008 0.006 0.007 0.007 0.004

-0.004 0.016 Cs-134

-0.003 0.007

-0.011 0.011

-0.008 0.012

-0.006 0.011

-0.003 0.007

-0.006 0.013

-0.008 0.011

-0.007 0.010 Cs-137 0.005 0.008 0.055 0.005

-0.001 0.008

-0.004 0.007 0.002 0.008

-0.001 0.003 0.058 0.007 0.004 0.010 Eu-152

-0.002 0.011

-0.005 0.011 0.002 0.020

-0.002 0.012 0.005 0.009

-0.002 0.018 0.004 0.009

-0.033 0.034 Eu-154 0.013 0.017

-0.003 0.020

-0.003 0.021

-0.002 0.014 0.005 0.017

-0.009 0.022

-0.009 0.016

-0.006 0.017 Eu-155 0.004 0.018 0.011 0.012

-0.004 0.011

-0.006 0.021 0.011 0.014 0.004 0.026

-0.014 0.020

-0.018 0.022 H-3 K-40 8.16 0.43 9.04 0.95 10.60 0.75 9.24 0.49 10.50 0.74 9.80 0.54 9.54 0.52 10.10 0.77 Nb-94

-0.002 0.004 0.001 0.003 0.001 0.002

-0.002 0.006 0.004 0.007

-0.003 0.004 0.002 0.003 0.003 0.004 Ni-59 Ni-63 Np-237

-0.006 0.015 0.001 0.009 0.002 0.013 0.000 0.000

-0.002 0.009

-0.011 0.014

-0.002 0.008

-0.007 0.014 Ra-226 0.206 0.013 0.235 0.035 0.168 0.021 0.177 0.013 0.187 0.020 0.182 0.016 0.209 0.017 0.202 0.043 Sb-125 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Sr-90 Th-228 0.254 0.014 0.208 0.016 0.181 0.016 0.202 0.013 0.17 0.22 0.204 0.015 0.193 0.014 0.204 0.029 Th-232 0.229 0.023 0.249 0.027 0.215 0.078 0.197 0.023 0.177 0.027 0.171 0.026 0.199 0.027 0.202 0.069 U-238 0.36 0.15 0.380 0.047 0.204 0.076 0.435 0.078 0.27 0.11 0.282 0.098 0.46 0.21 0.21 0.10 SOF Opc,d 0.001 0.02 0.00 0.00 0.001 0.006 0.02 0.001 SOF BCc,d 0.000 0.005 0.00 0.00 0.000 0.002 0.01 0.000

Zion DRP Confirmatory Survey Report B-17 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g), Cont.

Soil Sample ID 5375S0034 5375S0035 5375S0036 5375S0037 5375S0038 5375S0039 5375S0040 5375S0041 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m

-0.001 0.005

-0.006 0.007

-0.001 0.007

-0.001 0.005

-0.001 0.005 0.001 0.002

-0.001 0.007 0.001 0.005 Am-241

-0.004 0.007 0.01 0.11 0.006 0.049 0.000 0.001 0.002 0.003 0.005 0.014

-0.060 0.060

-0.022 0.070 Ba-133 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Co-60

-0.004 0.008

-0.002 0.008

-0.001 0.010 0.000 0.000 0.006 0.007 0.004 0.009

-0.003 0.006 0.002 0.009 Cs-134 0.001 0.006

-0.014 0.063 0.003 0.013

-0.009 0.011

-0.001 0.007

-0.010 0.011

-0.006 0.016 0.004 0.005 Cs-137 0.007 0.003 0.002 0.007 0.001 0.001 0.001 0.010

-0.001 0.004 0.010 0.006 0.001 0.006 0.018 0.005 Eu-152

-0.002 0.010

-0.002 0.020 0.008 0.015

-0.006 0.018 0.020 0.023

-0.002 0.012 0.005 0.015

-0.005 0.037 Eu-154

-0.006 0.018

-0.013 0.022

-0.012 0.031 0.010 0.026

-0.012 0.016 0.003 0.009

-0.017 0.029

-0.009 0.020 Eu-155 0.002 0.008 0.022 0.033 0.013 0.014 0.007 0.013 0.007 0.014 0.025 0.029 0.006 0.030

-0.017 0.023 H-3 K-40 10.50 0.89 10.70 0.82 10.50 0.74 10.10 0.69 10.30 0.69 9.71 1.03 14.40 0.98 11.40 0.73 Nb-94 0.003 0.005 0.001 0.001

-0.004 0.006

-0.002 0.007

-0.002 0.006 0.005 0.005

-0.001 0.009

-0.002 0.006 Ni-59 Ni-63 Np-237

-0.003 0.006 0.003 0.006 0.004 0.020

-0.001 0.012

-0.003 0.007

-0.006 0.010

-0.011 0.017

-0.003 0.010 Ra-226 0.196 0.066 0.173 0.047 0.186 0.019 0.185 0.016 0.181 0.015 0.306 0.054 0.375 0.057 0.297 0.019 Sb-125 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Sr-90 Th-228 0.24 0.23 0.17 0.22 0.180 0.016 0.177 0.014 0.177 0.013 0.261 0.019 0.444 0.031 0.311 0.015 Th-232 0.202 0.038 0.187 0.042 0.180 0.032 0.176 0.028 0.181 0.025 0.321 0.032 0.295 0.093 0.267 0.077 U-238 0.231 0.067 0.25 0.11 0.442 0.056 0.448 0.046 0.607 0.060 0.402 0.065 1.09 0.11 1.030 0.088 SOF Opc,d 0.002 0.0005 0.002 0.001 0.005 0.006 0.0004 0.009 SOF BCc,d 0.001 0.0001 0.000 0.000 0.001 0.002 0.0001 0.002

Zion DRP Confirmatory Survey Report B-18 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g), Cont.

Soil Sample ID 5375S0042 5375S0043 5375S0044 5375S0045 5375S0046 5375S0047 5375S0048 5375S0049 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m

-0.003 0.006

-0.010 0.010

-0.001 0.007

-0.003 0.009 0.001 0.003 0.001 0.007 0.001 0.003

-0.001 0.007 Am-241

-0.018 0.072

-0.006 0.012

-0.007 0.012

-0.001 0.010

-0.002 0.011 0.013 0.013

-0.020 0.026

-0.012 0.073 Ba-133 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Co-60 0.006 0.039

-0.005 0.009 0.001 0.005

-0.001 0.008 0.005 0.009

-0.001 0.010 0.002 0.016

-0.001 0.006 Cs-134

-0.002 0.018

-0.09 0.14

-0.002 0.006

-0.015 0.015

-0.014 0.014

-0.010 0.018

-0.005 0.008

-0.009 0.013 Cs-137 0.004 0.012

-0.002 0.008 0.032 0.005

-0.003 0.007 0.023 0.003 0.001 0.007

-0.002 0.004

-0.004 0.012 Eu-152

-0.014 0.023

-0.015 0.039

-0.009 0.023 0.005 0.017 0.003 0.005 0.011 0.024

-0.029 0.035

-0.018 0.034 Eu-154

-0.017 0.019

-0.015 0.028

-0.008 0.029 0.006 0.023

-0.005 0.025 0.012 0.029 0.004 0.028

-0.003 0.023 Eu-155 0.012 0.028 0.004 0.017

-0.007 0.020 0.013 0.014 0.007 0.013 0.003 0.020

-0.008 0.018 0.004 0.029 H-3 K-40 20.7 1.2 10.80 0.75 7.67 0.56 10.90 0.69 9.77 1.03 10.60 0.97 9.75 0.66 11.90 0.84 Nb-94

-0.005 0.006 0.006 0.007

-0.002 0.007

-0.006 0.006 0.001 0.006 0.005 0.005

-0.002 0.006

-0.007 0.007 Ni-59 Ni-63 Np-237 0.011 0.018 0.009 0.014

-0.016 0.031 0.003 0.011 0.003 0.010

-0.010 0.017

-0.005 0.012

-0.003 0.012 Ra-226 0.758 0.039 0.181 0.023 0.254 0.022 0.365 0.027 0.252 0.028 0.175 0.023 0.178 0.058 0.312 0.022 Sb-125 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR Sr-90 Th-228 0.787 0.047 0.176 0.016 0.216 0.018 0.280 0.019 0.195 0.015 0.17 0.22 0.177 0.013 0.334 0.022 Th-232 0.678 0.098 0.211 0.092 0.214 0.035 0.334 0.039 0.256 0.029 0.162 0.034 0.187 0.027 0.293 0.095 U-238 1.56 0.12 0.205 0.081 0.681 0.081 0.378 0.074 0.38 0.23 0.141 0.089 0.19 0.11 1.08 0.11 SOF Opc,d 0.007 0.00 0.01 0.00 0.01 0.0002 0.002 0.00 SOF BCc,d 0.002 0.00 0.003 0.00 0.003 0.00 0.0005 0.00

Zion DRP Confirmatory Survey Report B-19 5375-SR-01-0 Table B.5. Soil Sample Concentrations (pCi/g), Cont.

Soil Sample ID 5375S0050 5375S0051 5375S0052 5375S0053 5375S0054 5375S0055 5375S0056 Conc.a TPUb Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Conc.

TPU Ag-108m

-0.002 0.010

-0.002 0.011 0.013 0.014

-0.001 0.008

-0.008 0.008

-0.003 0.008

-0.002 0.007 Am-241

-0.007 0.012

-0.009 0.042 0.008 0.043

-0.03 0.10

-0.017 0.034 0.003 0.007

-0.029 0.073 Ba-133 NR NR NR NR NR NR NR NR NR NR NR NR NR NR Co-60 0.008 0.008

-0.003 0.006

-0.004 0.017

-0.003 0.016 0.005 0.015 0.008 0.005

-0.003 0.016 Cs-134

-0.010 0.014

-0.008 0.013 0.005 0.016

-0.014 0.015

-0.006 0.012

-0.011 0.012

-0.009 0.010 Cs-137 0.020 0.007 0.014 0.005 0.009 0.019 0.039 0.014 0.001 0.012 0.031 0.006 0.028 0.011 Eu-152 0.031 0.049 0.002 0.015

-0.015 0.036

-0.019 0.035

-0.012 0.027 0.009 0.006

-0.004 0.039 Eu-154

-0.017 0.028

-0.007 0.029

-0.008 0.015

-0.007 0.021

-0.003 0.019 0.005 0.021 0.009 0.017 Eu-155 0.003 0.013 0.002 0.003

-0.008 0.023 0.008 0.015

-0.005 0.023 0.005 0.014 0.009 0.017 H-3 K-40 10.10 0.79 7.93 0.64 5.70 0.56 7.83 0.58 3.18 0.47 7.80 0.46 6.53 0.39 Nb-94

-0.004 0.007

-0.005 0.006

-0.003 0.006 0.001 0.003

-0.002 0.010

-0.003 0.006 0.002 0.003 Ni-59 Ni-63 Np-237

-0.059 0.086

-0.002 0.012

-0.014 0.023 0.009 0.013

-0.006 0.018 0.002 0.011

-0.005 0.014 Ra-226 0.246 0.053 0.270 0.021 0.208 0.025 0.236 0.058 0.135 0.043 0.252 0.035 0.275 0.053 Sb-125 NR NR NR NR NR NR NR NR NR NR NR NR NR NR Sr-90 Th-228 0.212 0.020 0.244 0.017 0.162 0.015 0.213 0.016 0.111 0.036 0.232 0.016 0.240 0.033 Th-232 0.232 0.040 0.247 0.033 0.174 0.032 0.220 0.092 0.116 0.028 0.248 0.035 0.249 0.091 U-238 0.921 0.058 0.369 0.077 0.14 0.12 0.21 0.12 0.12 0.11 0.39 0.77 0.36 0.11 SOF Opc,d 0.01 0.004 0.01 0.01 0.005 0.02 0.008 SOF BCc,d 0.003 0.001 0.001 0.003 0.001 0.004 0.002 a Results that are considered statistically positive are bolded.

b Uncertainties are based on total propagated uncertainties at the 95% confidence level. 2 sigma uncertainty is presented.

c Only Co-60, Cs-134, Cs-137, Ni-63, and Sr-90 concentrations are used in SOF calculation.

d Samples S0001, S0006, S0007, S0009, S0014, S0015, and S0016 are subsurface samples (>15 cm in depth) so the subsurface soil DCGLOp was used in the SOF calculations.

Zion DRP Confirmatory Survey Report 5375-SR-01-0 APPENDIX C: MAJOR INSTRUMENTATION

Zion DRP Confirmatory Survey Report C-1 5375-SR-01-0 C.1. SCANNING AND MEASUREMENT INSTRUMENT/

DETECTOR COMBINATIONS The display of a specific product is not to be construed as an endorsement of the product or its manufacturer by the author or their employer.

C.1.1 GAMMA Ludlum NaI[Tl] Scintillation Detector Model 44-10, Crystal: 5.1 cm x 5.1 cm (Ludlum Measurements, Inc., Sweetwater, Texas)

Coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas)

Coupled to: Trimble Geo 7X or Trimble Geo XH (Trimble Navigation Limited, Sunnyvale, CA)

Detector used in conjunction with:

Ludlum Lead Collimator Model 4260-079, as needed

Zion DRP Confirmatory Survey Report 5375-SR-01-0 APPENDIX D: SURVEY AND ANALYTICAL PROCEDURES

Zion DRP Confirmatory Survey Report D-1 5375-SR-01-0 D.1. PROJECT HEALTH AND SAFETY The Oak Ridge Institute for Science and Education (ORISE) performed all survey activities in accordance with the Oak Ridge Associated Universities (ORAU) Radiation Protection Manual, the ORAU Radiological and Environmental Survey Procedures Manual, and the ORAU Health and Safety Manual (ORAU 2020b, ORAU 2016, and ORAU 2020). Prior to on-site activities, a Work-Specific Hazard Checklist was completed for the project and discussed with field personnel. The planned activities were thoroughly discussed with site personnel prior to implementation to identify hazards present.

Should ORISE have identified a hazard not covered in ORAU 2016 or the projects Work-Specific Hazard Checklist for the planned survey and sampling procedures, work would not have been initiated or continued until the hazard was addressed by an appropriate job hazard analysis and hazard controls.

D.2. CALIBRATION AND QUALITY ASSURANCE Calibration of all field instrumentation was based on standards/sources traceable to National Institute of Standards and Technology (NIST).

Field survey activities were conducted in accordance with procedures from the following documents:

• ORAU Radiological and Environmental Survey Procedures Manual (ORAU 2016)

• ORAU Environmental Services and Radiation Training Quality Program Manual (ORAU 2022)

The procedures contained in these manuals were developed to meet the requirements of U.S. Department of Energy (DOE) Order 414.1D and U.S. Nuclear Regulatory Commissions (NRCs) Quality Assurance Manual for the Office of Nuclear Material Safety and Safeguards and contain measures to assess processes during their performance.

Quality control procedures include:

• Daily instrument background and check-source measurements to confirm that equipment operation is within acceptable statistical fluctuations.

• Training and certification of all individuals performing procedures.

• Periodic internal and external audits.

Zion DRP Confirmatory Survey Report D-2 5375-SR-01-0 D.3. SURVEY PROCEDURES D.3.1 SURFACE SCANS Scans for elevated gamma radiation were performed by passing the detector slowly over the surface.

The distance between the detector and surface was maintained at a minimum. The thallium-doped sodium iodide (NaI) scintillation detectors were used solely as a qualitative means to identify elevated radiation levels in excess of background based on an increase in the audible signal from the indicting instrument. The surveys focused on identifying DRPs/DROs considering the technical basis outlined in Estimating Scan Minimum Detectable Activities of Discrete Radioactive Particles (ORISE 2022) and summarized below.

In summary, ORISE 2022 considered two conceptual models including the following for only an unshielded detector:

• Optimistic and pessimistic (offset) survey pathways using a 2x2 NaI detector,

• Co-60, Cs-137, Th-232, and Am-241 DRPs,

• Detector heights of 7.5 cm and 10 cm,

• Soil cover depth of 0 cm, 7.5 cm, 15 cm, and 30 cm (calculations for a depth cover of 30 cm was only performed for Co-60 and Cs-137), and

• Surveyor scan speed of 0.25 m/s, 0.5 m/s, and 1 m/s The scan MDC equationfor land area gamma scanspresented for the standard model in NUREG-1507 can be slightly reformatted for a DRP as:

=

=

Where:

scan MDA

= scan minimum detectable activity (µCi)

MDCt

= minimum detectable counts (counts) d

= index of sensitivity, 1.64 used here (unitless) bi

= background counts during observation interval (counts); a background count rate of 10,000 cpm was assumed I

= observation interval (seconds)

IR

= integrated detector response [R(, t)] over observation interval (cpm/µCi s) p

= surveyor efficiency, 0.5 used here (unitless)

Zion DRP Confirmatory Survey Report D-3 5375-SR-01-0 Note, the scan MDA equation above differs from Equation 6.11 in NUREG-1507 by the removal of (60/i), which corrects MDCt to the MDCR in Equation 6.11. The MDCR term is unnecessary in this method because the NaI detector response is integrated over the observation interval.

Table B.1 presents scan MDA values for all modeled combinations of radionuclides, offset, and depth for a surveyor velocity of 0.5 m/s. Optimistic values are provided on the top portion of the table, representing the MDA assuming the detector passes directly over the DRP. Pessimistic values are provided on the bottom portion of the table, representing the MDA assuming the DRP is located within the straight-line path of the surveyor but is positioned at a maximum distance from the detectors serpentine path.

Table B.1. DRP scan MDA for various scan conditions and a surveyor velocity of 0.5 m/s

(µCi)

Particle Depth in Soil Radionuclide and Ground-to-Detector Distance Co-60 Cs-137 Th-232 Am-241 7.5 cm 10 cm 7.5 cm 10 cm 7.5 cm 10 cm 7.5 cm 10 cm Optimistic Scenario Surface 0.12 0.15 0.23 0.29 0.06 0.07 0.50 0.63 7.5 cm 0.22 0.25 0.47 0.54 0.16 0.19 15 cm 0.43 0.48 1.09 1.21 0.41 0.46 30 cm 1.7 5.9 Pessimistic Scenario Surface 0.52 0.53 1.0 1.1 0.27 0.28 2.41 2.46 7.5 cm 0.99 0.94 2.5 2.3 0.93 0.86 15 cm 1.7 1.6 4.9 4.6 1.9 1.8 30 cm 4.9 19.9

- indicates the calculation shows the DRP cannot be identified during scans.

All values rounded to two significant digits or the hundredth position.

For the measurement of soils where volumetric derived concentration guideline levels (DCGLs) were applicable, the confirmatory survey considered the gross gamma DCGLOp (3.4 pCi/g) used for final status survey (FSS) planning purposes. However, the scan survey also measured for the presence of particles in areas investigated, which was the limiting scan survey requirement. Using the scan minimum detectable concentration (MDC) calculation approach outlined in NUREG-1507, the a priori confirmatory scan sensitivity was evaluated. The calculation used the following inputs:

Zion DRP Confirmatory Survey Report D-4 5375-SR-01-0

• Index of sensitivity = 1.38

• Observation interval = 2 seconds (based on a source diameter of 0.25 m2 and 0.25 m/s surveyor velocity)

• Detector background = 7,500 counts per minute (cpm) (this value varies considerably across the site; collimator use on the detector reduced this value by a factor of 2 or 3)

• Surveyor efficiency = 0.75

• Radionuclide of concern (ROC) fraction = 0.05 for Co-60; 0.95 for Cs-137 Based on the above inputs, the scan MDC for cobalt-60 (Co-60) and cesium-137 (Cs-137) was 1.7 picocuries per gram (pCi/g) and 3.4 pCi/g, respectively, when a collimator was not used. The corresponding gross scan MDC was 3.2 pCi/g, which was below the gross DCGLOp. The corresponding minimum detectable count rate for the surveyor (MDCRSurveyor) was 750 counts per minute (cpm). The MDCRSurveyor served as the gamma investigation level (IL). The use of collimators reduce the background count rate of the detector, and, depending on the actual background count rate during scan surveys, the gross scan MDC/MDA would be reduced. The ORISE 2022 scan protocol for particles was used in all survey units, with the measurement goal of detecting less than 1 microcurie (µCi ) of Co-60 at the soil surface and to a depth of 6 inches. Note that the survey design basis was focused on detecting Co-60 particles. Scan sensitivities presented in this section met the goals outlined in data quality objectives (DQO) Step 6 (i.e., scan MDC less than the DCGLOp for volumetric contamination and less than 1 µCi for a Co-60 particle to a depth of 15 cm with one exception. ORISE 2022 indicates that 1.7 µCi of Co-60 is detectable at 15 cm for the pessimistic scenario noting a 10,000 cpm background was assumed in the ORISE 2022 study. Actual background values varied during surveys at the site.

D.3.2 SOIL SAMPLING Soil samples (approximately 1 kilogram each) were collected by ORISE personnel using a clean hand trowel to transfer soil into a new sample container. All containers were labeled and security sealed in accordance with ORISE procedures.

DRP/DRO samples were placed in small plastic specimen cups with screw top lids which were also sealed with tape and then placed within plastic 6-millimeter-thick poly re-sealable bags. Only the amount of material necessary to contain the particle was placed in the specimen cup. Further

Zion DRP Confirmatory Survey Report D-5 5375-SR-01-0 separation was performed at the laboratory to isolate the particles. Samples were shipped under chain-of-custody to the selected laboratory, the Radiological and Environmental Sciences Laboratory (RESL) in Idaho Falls, Idaho for analysis.

D.4. RADIOLOGICAL ANALYSIS D.4.1 GAMMA SPECTROSCOPY Following volumetric soil sample preparation, a portion was sealed in a size appropriate container.

The quantity placed in the container was chosen to reproduce the calibrated counting geometry. Net material weights were determined, and the samples were counted using intrinsic, high-purity, geranium detectors coupled to a pulse-height analyzer system. Background and Compton stripping, peak search, peak identification, and concentration calculations were performed using computer capabilities inherent in the analyzer system. Results for the requested radionuclides of concern were provided in units of picocuries per gram (pCi/g).

DRP/DRO samples were treated with the general procedure outlined in Section 5 to isolate the activity source. This approach allowed the placement of the particle(s) in a point source geometry without attenuation from other sample materials. This also minimized the amount of material that would subsequently be used for chemical separation. Due to particle size and elevated responses by the instrumentation, RESL performed gamma spectroscopy utilizing a point source calibration at approximately 11 cm above a high-purity germanium detector. DRP/DRO samples M0003 and M0004-1 were counted again after total dissolution utilizing a known calibrated geometry. The utilization of the point source calibration at ~11 cm appears to provide a slightly conservative

[larger] estimate of total activity, as the results of the re-counts of samples M0003 and M0004-1 after total dissolution utilizing a known calibrated geometry were lower. Background and Compton stripping, peak search, peak identification, and concentration calculations were performed using computer capabilities inherent in the analyzer system. Results for the DRP/DRO samples were provided in units of picocuries per sample (pCi/sample).

D.4.2 RADIOACTIVE STRONTIUM ANALYSIS Strontium-90 (Sr-90) concentrations were quantified by total sample dissolution followed by radiochemical separation and are counted on a low background liquid scintillation counter. Soil samples are dissolved by a combination of potassium hydrogen fluoride and pyrosulfate fusions.

Zion DRP Confirmatory Survey Report D-6 5375-SR-01-0 Water samples are concentrated, and strontium is separated as a sulfate with further purification.

The sulfate-salts are dissolved in ethylenediaminetetraacetic acid (EDTA). The strontium is separated from residual calcium by re-precipitating strontium sulfate from the EDTA. Strontium sulfate is separated from barium by complexing the strontium sulfate in EDTA and precipitating barium sulfate at a pH of 6. The complexed strontium is precipitated as the sulfate and redissolved in EDTA. The yttrium-90 (Y-90) is allowed to in grow, and the final sample is counted via Cherenkov counting on a liquid scintillation counter. The typical MDC for a 200-minute count time using this procedure is approximately 1 pCi/g for a 1-gram sample.

D.4.3 H-3 ANALYSIS Tritium (H-3) analysis for soil samples are performed using custom distillation glassware and counted by liquid scintillation. The H-3 distillate is collected and mixed with ultima gold LLT liquid scintillation cocktail. The typical MDC for H-3 for a 100-minute count time using this procedure is approximately 2 pCi/g.

D.4.4 NI-63 ANALYSIS Soil samples are spiked with a nickel (Ni) and cobalt carrier and digested with a mixture of nitric and hydrochloric acids or fused with potassium fluoride/pyrosulfate fusions. Unwanted elements, such as iron and cobalt, are removed via anion exchange chromatography. Nickel is then further separated from the potential interfering elements using a dimethyl glyoxime (DMG) and buffered ammonium citrate. The purified nickel is dissolved in a dilute nitric acid solution, UGLLT liquid scintillation cocktail is added, and the Ni-63 activity is determined via liquid scintillation counting.

The typical MDC for a 1-gram sample and 100-minute count time using this procedure is approximately 2 pCi/g.

D.4.5 DETECTION LIMITS Each RESL analytical result is accompanied by its total propagated uncertainty expressed at one standard deviation. All results for which the 95% confidence interval does not contain zero are considered statistically positive (i.e. a detect) for the given analyte. Because of variations in background levels, measurement efficiencies, and contributions from other radionuclides in samples, the detection limits differed from sample to sample and instrument to instrument.