ML25345A216

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Technical Support Document, Guideline for Embedded and Buried Pipe Detector Calibration and Usage, Revision 4
ML25345A216
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Site: Crystal River  Duke Energy icon.png
Issue date: 12/11/2025
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ADP CR3
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Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation
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3F1225-02
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ENCLOSURE 13 Crystal River Unit 3 Nuclear Generating Plant Docket Nos. 50-302 / 72-1035 Operating License DPR-72 Technical Support Document, Guideline for Embedded and Buried Pipe Detector Calibration and Usage Begins On Next Page 3F1225-02 / Enclosure 13 lef

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 Crystal River 3 Nuclear Power Plant - Technical Basis Document Guideline for Embedded and Buried Pipe Detector Calibration and Usage Revision 4 November 13, 2025 Prepared by: Claude Wiblin, CHP, Chesapeake Nuclear Services, Inc.

Reviewed by: J. Stewart, Bland, CHP, Chesapeake Nuclear Services, Inc.

Reviewed by: Marshall H Blake, FSS Engineering Supervisor, CR3 & VY Reviewed by: Chuck Burtoff, CHP, ADP CR3 Decommissioning Approved by: Leon Bryant Akins Jr., RPM, ADP CR3 Decommissioning 3F1225-02 / Enclosure 13 / Page 1 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 i

Contents List of Figures........................................................................................................................... i List of Tables............................................................................................................................. i List of Attachment.................................................................................................................... i 1.0 Introduction and Purpose................................................................................................ 1 2.0 CR3 Pipe Detectors........................................................................................................ 2 3.0 Pipe Sizing..................................................................................................................... 5 4.0 DCGLs and Fractional Abundances................................................................................ 6 5.0 Pipe Detector Dimensioning........................................................................................... 7 6.0 Efficiencies, MDCs, and Concentrations......................................................................... 8 6.1 Efficiency Factor Determination............................................................................... 8 6.2 On-site Calibration Summary and Results.............................................................. 11 6.3 Minimum Detectable Count Rate (MDCR)..............................................................15 6.4 Concentrations at Measurement Locations............................................................17 7.0 Field Application Guidance............................................................................................18 8.0 References....................................................................................................................20 List of Figures Figure 1. Available Models of Pipe Detectors............................................................................. 3 Figure 2. Model 44-159-1 Diagram Showing Crystal Center is 0.75 inches from End................. 4 Figure 3. Model 44-157 Diagram Showing Crystal Center is 2.28 inches from End.................... 4 Figure 4. Model 44-162 Diagram Showing Crystal Center is 2.56 inches from End.................... 5 Figure 5. Typical Illustration of Geometry and Location of Detector Crystal................................ 7 Figure 6. Locations of Crystals for Calibrations.........................................................................11 List of Tables Table 1 - Reactor Building and BOP Action Level Allowance for Pipes...................................... 6 Table 2 - Pipe Detector Specifics.............................................................................................. 7 Table 3 - Calibration Results with a Cs-137 Disk Source.........................................................12 Table 4 - Co-60 Energy Response Normalized to Cs-137 per Detector...................................13 Table 5 - Total Interior Area of 1-foot Pipe Segment................................................................14 Table 6 - Detector Efficiencies for Pipes in the Reactor Building..............................................14 Table 7 - Detector Efficiencies for Pipes in BOP......................................................................15 Table 8 - MDCR for Static Measurements................................................................................16 Table 9 - Minimum Detectable Concentrations.........................................................................17 Table 10 - Net Detector Response Equivalent to Action Level for Buried Pipes........................18 List of Attachment Attachment A - Calibration Source Certificate...........................................................................21 Attachment B - Development of ERC and CPMR for Gamma Detectors..................................24 3F1225-02 / Enclosure 13 / Page 2 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 1 1.0 Introduction and Purpose The purpose of this Technical Basis Document (TBD) is to support the application of survey and sampling of embedded and buried piping that will remain in place after the decommissioning of Crystal River Unit 3 (CR3). Final Status Survey (FSS) plans will be developed addressing the survey methods, data analysis, and compliance evaluation for embedded and buried piping, which will include survey unit data quality objectives (DQOs).

The FSS plans will include the following items:

Identifying radionuclides of interest and correlating Hard to Detects (HTDs), as needed; Determining detector sensitivity and related scan and fixed minimum detectable levels; Measuring total and removable residual radioactivity levels; Visually examining internal surface condition of the piping and presence of foreign or residual materials (e.g., sediments);

Visually examining piping geometry and presence of internally inaccessible areas/sections; and Visually inspecting the pipes for potential leaks that may have impacted the surrounding soils.

The approach for measuring the concentrations of residual radioactivity of embedded or buried piping is the same. The average concentration will be calculated based on the interior area of the pipe and the average measurement made in each pipe. The measurements and correlated activities will be included in the evaluation for the subsurface walls and foundations as addressed in the License Termination Plan Chapter 6 [8-1].

The residual radioactivity remaining in each section of embedded or buried piping will be assessed and quantified by direct survey. Any inaccessible piping will require removal or physical examination/access, allowing for sampling and/or surveying in accordance with the methods described herein. Shallow penetrations or short lengths of embedded pipe that are directly accessible will be surveyed using hand-held portable detectors, such as the Ludlum 43-93 zinc sulfide or 44-10 sodium iodide scintillation detectors.

There are three different model detectors: two types of cesium iodide (CsI) models, and a sodium iodide (NaI) model. All are available for use at CR3, each with a unique size detection crystal and calibration for determining radioactivity in nine different diameter pipes ranging from 1 inch to 48 inches. One-minute measurements are planned at 1-foot intervals and are the average measurement used in compliance criteria.

As there are no centering vanes on the detectors, the correlation of measurements to pipe activity levels, as developed in this TBD, is based on multi-point measurements collected from both the centerline of the crystal of each detector and from the bottom of the detector, which is considered to be the highest concentration of residual radioactivity in a pipe. The average of the changes of photon intensity is made from the bottom of the pipe interior to the crystal and 3F1225-02 / Enclosure 13 / Page 3 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 2 applied as the source activity over the total area in a 12-inch-long pipe segment. To convert to conventional units of counts per minute (cpm) per disintegrations per minute (dpm) per 100 square centimeters (cm2). The effective area is then defined by dividing the total area by 100 to represent the activity over a 100 cm2 area.

The output of these detectors represents the gamma activity of the residual radioactivity content inside the pipes. Details on detection limits, minimum detectable concentrations (MDCs), and values to be used for compliance are described in Section 6.

There is no elevated measurement comparison (EMC) applicable to embedded pipe or penetrations. Any measurement exceeding 75% Investigation Level of the Derived Concentration Guideline Level (DCGL) will be investigated, which may include additional measurements and/or remediation.

Detailed discussion is provided in the following Sections with guidance from:

United States Nuclear Regulatory Commission (NRC) Intermediate Staff Guidance (ISG), Radiological Survey and Dose Modeling of the Subsurface to Support License Termination [8-6].

NUREG-1757 Vol. 2, Rev. 2, Consolidated Decommissioning Guidance:

Characterization, Survey, and Determination of Radiological Criteria - Final Report [8-7].

NUREG-1575, Rev. 1, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), [8-8].

Section 7.0, Field Application Guidance, provides guidance to be considered for performing the field surveys.

2.0 CR3 Pipe Detectors As depicted in Figure 1, CR3 possesses three Ludlum Model pipe detectors: the 44-157, 44-159-1, and 44-162. The Model 44-157 consists of a 2-inch by 2-inch NaI crystal, the Model 44-159-1 consists of an 18-millimeter (mm) by 18-mm CsI crystal, and the Model 44-162 consists of a 3-inch by 3-inch NaI crystal; all are coupled to a photomultiplier tube housed in aluminum. In the development of detector efficiencies, each has a unique distance between the edge of the crystal closest to the inner pipe edge and the distance to the inner pipe, i.e., there is a mounting distance and location to be accounted for in each of them. Figure 1 provides a comparative look at the three detectors, while Figures 2 through 4 provide details [8-2].

3F1225-02 / Enclosure 13 / Page 4 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 3 Figure 1. Available Models of Pipe Detectors44-162 44-157 44-159 3F1225-02 / Enclosure 13 / Page 5 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 4 Figure 2. Model 44-159-1 Diagram Showing Crystal Center is 0.75 inches from End Figure 3. Model 44-157 Diagram Showing Crystal Center is 2.28 inches from End 2.28 3 22B

[81. 3 m]

2 00mm]

D

...... --------1--- 6.12-----------

0 CENTERLINE 2 X 2 Nal CRYSTAL 3F1225-02 / Enclosure 13 / Page 6 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 5 Figure 4. Model 44-162 Diagram Showing Crystal Center is 2.56 inches from End 2.56" 3.0 Pipe Sizing Some CR3 Storm Drain systems involve additional complications as corrugated metal pipes (CMP) are generally used with diameters ranging from 12 inches to 42 inches; corrugations are usually 1/2 inch or 1 foot deep. Further, process piping for the Intake, Discharge, and RAW Water varies at 48 inches, 78 inches, and 90 inches in diameter as cast iron pipe, reinforced concrete pipe, and formed concrete. Each pipe must be measured or estimated for its internal diameter.

Corrugation depths may be averaged.

Contamination is measured in each pipe, with the appropriate detector based on the inside diameter of the pipe and the exterior diameter of the detector shell. For example, it would not be appropriate to measure a 4-inch pipe with the small 44-159-1 detector; similarly, neither the 44-159-1 nor the 44-157 is appropriate for an 8-inch pipe. The largest detector that fits into a pipe should be used. Residual radioactivity in pipes greater than 48 inches in diameter will be determined by other survey techniques such as hand scanning by FSS technicians if safely accessible. This TBD evaluates survey requirements and techniques for various pipe diameters.

3F1225-02 / Enclosure 13 / Page 7 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 6 4.0 Action Levels and Fractional Abundances Consideration is made for Action Levels (ALs) and fractional abundances for gross measurements, which may be applied for evaluating pipe detector response and ALs. LTP Chapter 6 provides Gross Activity Action Levels for various pipe diameters which is based upon an LLBP activity with a 30-y delay in performance. The gross activity action level value for the Reactor Building and the Balance of Plant (BOP) Buildings is 19.1 pCi/g for the conversion to equivalent volumetric subsurface Action Levels in dpm/100 cm2. Values for the various pipe diameters are provided in Table 1.

Table 1 - Reactor Building and BOP Action Level Allowance for Pipes Pipe Diameter (inches)

Pipe Radius (cm)

Pipe Segment Area (cm2)

Qbucket/Area (dpm/cm2)

BOP Action Level for Surfaces (dpm/100 cm2) 1 1.3 7.98E+02 7.97E+04 8.0E+06 2

2.5 1.60E+03 3.99E+04 4.0E+06 4

5.1 3.19E+03 1.99E+04 2.0E+06 6

7.6 4.79E+03 1.33E+04 1.3E+06 8

10.2 6.38E+03 9.96E+03 1.0E+06 10 12.7 7.98E+03 7.97E+03 8.0E+05 18 22.9 1.44E+04 4.43E+03 4.4E+05 24 30.5 1.92E+04 3.32E+03 3.3E+05 36 45.7 2.87E+04 2.21E+03 2.2E+05 48 61.0 3.83E+04 1.66E+03 1.7E+05 Source: LTP Chapter 6, Table 6.15.

3F1225-02 / Enclosure 13 / Page 8 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 7 5.0 Pipe Detector Dimensioning For each detector model, Ludlum has also provided specific detector sizes, dimensions, and sensitivity to gamma radiation, which are presented in Table 2[8-2].

Table 2 - Pipe Detector Specifics Detector Exterior Crystal Size Sensitivity for Cs-137 (cpm/R/hr)

Crystal Radius Distance from Crystal Edge to Pipe 44-159-1 0.875" dia. X 3.2" L 0.709"x0.709" 120 0.354 0.083 44-157 3.5" dia. X 6.1" L 2"x2" 900 1.0" 0.75 44-162 7.5" dia. X 9.5" L 3"x3" 2300 1.5" 2.25 Notes:

cpm/R/hr = counts per minute per microroentgen per hour dia. = diameter L = length

" = inch/inches X = by The aluminum housing is about 0.05 inches thick. For the calibration techniques proposed, the aluminum shielding is inherent to the process and does not require separate evaluation.

Figure 5 presents an illustration of the approximate location of the detector crystal inside a pipe; there is always an air gap between the crystal and the pipe interior. The distances vary as the detector is always at the bottom of the pipe, noting that the crystals within the detector are not the same size and are located differently in each detector (see Figures 2, 3, and 4).

Figure 5. Typical Illustration of Geometry and Location of Detector Crystal z

z ----4-.

Center X

Side View Top View X 3F1225-02 / Enclosure 13 / Page 9 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 8 6.0 Efficiencies, MDCs, and Concentrations An initial calibration was performed, which involved taking 13 measurements along a 1-foot length of pipe with a calibration source at the middle of the 1-foot segment (see Figure 6). The crystal center inside the detector is always directly over the measurement locations and not the center of the detector. The results are averaged to give a gross cpm, then with background subtracted, the net is divided to yield an efficiency (Eff Factor) in units of cpm/dpm for the entire area of the pipe segment. This Eff Factor is converted to conventional units of cpm/dpm/100cm2 by dividing it by an area factor (AF), which is the total area of a 1-foot-long pipe segment, by 100.

6.1 Efficiency Factor Determination 6.1.1 Select the detector and meter pairing, as well as the length of cable consistent with manufacturers specifications to be used. Ensure the detector and meter pair have been response checked. Record the pipe size, meter/detector type, serial numbers, calibration date, calibration due date, and the detector cable length for the detector and meter pairing on CR3 forms. This information should be placed on the calibration sticker/label on the survey meter to ensure field technicians are aware of the limitations of the survey instrument pairing configuration.

6.1.2 Ensure that the parameter settings for the meter (e.g., voltage, etc.) are set to the values specified for the primary radionuclide to be surveyed per the certificate of calibration for the paired detector.

6.1.3 Connect the detector to the meter using the appropriate cable length with the meter de-energized.

NOTE 2 Ensure to the extent practical that the area selected to determine meter background is free of residual radioactive contamination and that any radiological sources stored in or near the area are properly shielded to mitigate any influence on background.

NOTE 1 The maximum length of the detector cable used will not exceed the length of the cable that was used during the calibration of the detector and data logger pairing.

3F1225-02 / Enclosure 13 / Page 10 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 9 6.1.4 Set the scaler count time for background determination. The minimum count time for background determination is 600 seconds or 10 minutes. Longer background count times may be used.

6.1.5 Install the selected detector into the clean pipe commensurate with the internal diameter size of the pipe to be surveyed, allow the detector to stabilize, and record the size of the pipe applicable to this Eff Factor determination in Attachment B.

6.1.6 Initiate a background count.

6.1.7 Record the background counts on CR3 forms.

1.)

Calculate and record the result of the background count.

2.)

Establish an acceptable background range of +/- 20%.

6.1.8 Set the scaler count time for source counts. The minimum count time for Eff Factor determination is 60 seconds or 1 minute. Longer source count times may be used.

6.1.9 Place the National Institute of Standards and Technology (NIST) traceable radiological source into the pipe interior by placing the source into the interior surfaces of the pipe.

1.)

Ensure the exposure surface of the source is secured to the pipe by use of magnets or other means.

2.)

If there is overlap in the area of the source, then ensure (to the extent practical) the overlap is positioned at the bottom of the pipe.

3.)

Mark the source edges within the pipe to ensure the source is positioned in the same geometry for all subsequent Eff Factor determinations.

6.1.10 Initiate source counts at each of the following thirteen positions:

1.)

Position 1: Detector positioned with the detector crystal centerline, 6 inches left of the source centerline. (See Figure 6) 2.)

Position 2: Detector positioned with the detector crystal centerline, 5 inches left of the source centerline. (See Figure 6) 3.)

Position 3: Detector positioned with the detector crystal centerline, 4 inches left of the source centerline. (See Figure 6)

NOTE 3 A separate background determination must be made for each detector and meter pairing.

3F1225-02 / Enclosure 13 / Page 11 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 10 4.)

Position 4: Detector positioned with the detector crystal centerline, 3 inches left of the source centerline. (See Figure 6) 5.)

Position 5: Detector positioned with the detector crystal centerline, 2 inches left of the source centerline. (See Figure 6) 6.)

Position 6: Detector positioned with the detector crystal centerline, 1 inch left of the source centerline. (See Figure) 7.)

Position 7: Detector positioned with the detector crystal centerline, 0 inches from the source centerline. (See Figure 6) 8.)

Position 8: Detector positioned with the detector crystal centerline, 1 inch right of the source centerline. (See Figure 6) 9.)

Position 9: Detector positioned with the detector crystal centerline, 2 inches right of the source centerline. (See Figure 6) 10.) Position 10: Detector positioned with the detector crystal centerline, 3 inches right of the source centerline. (See Figure 6) 11.) Position 11: Detector positioned with the detector crystal centerline, 4 inches right of the source centerline. (See Figure 6) 12.) Position 12: Detector positioned with the detector crystal centerline, 5 inches right of the source centerline. (See Figure 6) 13.) Position 13: Detector positioned with the detector crystal centerline, 6 inches right of the source centerline. (See Figure 6) 3F1225-02 / Enclosure 13 / Page 12 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 11 Figure 6. Locations of Crystals for Calibrations 6.1.11 Record the source counts on CR3 standard survey forms.

1.) Divide the gross counts by the count time to derive gross cpm.

2.) Subtract the mean background count from each gross cpm value to derive net cpm.

6.1.12 Calculate the mean net cpm for the 13 background corrected source counts (net cpm for positions 1 through 13) and record this information on CR3 survey forms.

6.2 On-site Calibration Summary and Results On May 22, 2024, an on-site calibration was performed for the three detectors in accordance with the requirements listed in Section 6.1. The calibration was performed with a Cs-137 disk source strength of 10 microcurie (Ci) as of July 7, 2020; a certificate is enclosed in Attachment A. The results of the measurements and their averages are presented in Table 4. The average Eff Factor for a 12-inch pipe segment is calculated from the results of the measurements using the following equation:

= () ()

()

The Eff Factor is developed for each detector and presented in Table 34.

12 inches 0

1 2

3 4

5 6

-6

-5

-4

-3

-2

-1 X

Y 1

2 0

7 8

9 10 12 11 13 1

2 3

5 4

6 Crystal Centerline Positions Source Centerline NOTE 4 The mean source count is recorded in units of cpm. The Surface Emission Rate (SER) of a source is typically presented in units of activity. To calculate the efficiency factor, the SER units must be converted to units of dpm (1 Ci = 3.7E+10 dps = 2.22E+12 dpm).

00000 000000 t

t t

t t

t t

t t

t t

t 3F1225-02 / Enclosure 13 / Page 13 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 12 Table 3 - Calibration Results with a Cs-137 Disk Source Crystal Center-Line Location (inches from Disk centerline)

Ludlum 44-159-1 (cpm)

Ludlum 44-157 (cpm)

Ludlum 44-162 (cpm)

+6 inches 5.75E+03 5.29E+04 2.24E+05

+5 inches 9.56E+03 7.28E+04 2.78E+05

+4 inches 1.44E+04 1.05E+05 3.49E+05

+3 inches 2.35E+04 1.61E+05 4.34E+05

+2 inches 4.49E+04 2.76E+05 5.33E+05

+1 inch 1.26E+05 4.72E+05 6.26E+05

  • 0 inches 7.32E+05 5.84E+05 5.97E+05

-1 inch 2.19E+05 3.65E+05 3.86E+05

-2 inches 4.47E+04 1.94E+05 2.89E+05

-3 inches 1.77E+04 1.08E+05 2.22E+05

-4 inches 8.17E+03 7.20E+04 1.81E+05

-5 inches 4.81E+03 4.94E+04 1.46E+05

-6 inches 3.10E+03 3.56E+04 1.16E+05 Averages 9.65E+04 1.96E+05 3.37E+05 Backgrounds (during measurements) 60 305 1,885 Eff Factor (cpm/dpm) 0.0047 0.0096 0.0165

  • This is the centerline of the internal detector crystal.

+ indicates front of detector

- indicates backside of detector towards the cable connection Attachment B provides energy response curves for each of the detectors and an introduction to the NUREG-1507 [8-4] techniques for evaluation of count -rate -to -exposure -rate ratio (CPMR) and the exposure-rate-to-concentration ratio (ERC). Application of Microshield [8-3] modeling code is required, and a multiple of the Co-60 responses to Cs-137 for each detector is made; see the attachment and results in Table 4.

3F1225-02 / Enclosure 13 / Page 14 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 13 Table 4 - Co-60 Energy Response Normalized to Cs-137 per Detector Model Co-60 Multiple of Cs-137 Response 44-159-1 0.35 44-157 0.40 44-162 0.44 For the mix and fractional abundances for the Reactor Building and BOP, a ratio of Co-60 to Cs-137 is performed via comparison of the respective fractional abundance (fi). As noted in Chapter 5 of the LTP, considering only the gamma-emitting radionuclides, the Co-60 portion (P) is 26% and the Cs-137 portion is 74% of the total activity for the two radionuclides. Similarly, for the BOP, Cs-137 is 100% of the total activity. The Eff Factor, EFFSOF, in units of cpm/dpm for a mix is calculated for each detector by:=

137 x 137 + 60 x 60 The efficiency curves provided by Ludlum [8-2] show efficiency relative to that for the 0.662 megaelectron volt (MeV) gamma for Cs-137. Therefore, the Eff FactorCo-60 may be presented as proportional to the Eff FactorCs-137. As an example, for the Reactor Building and the 44-159-1 detector, the above EffSOF can be calculated as follows:

= 137 x 137 + 60 x ( 60)x 137

= 0.7429 x.0047 + 0.271 x (0.35 x 0.0047) = 0.0039 cpm/dpm The Eff Factor, as shown in Table 5, represents the modeling for a source geometry represented by a 1-foot pipe length. Therefore, the above calculated EffSOF represents the overall efficiency for activity distributed along the 1-foot pipe length. To correlate this efficiency to the conventional units of cpm/dpm/100 cm2, an AF is used to represent the number of 100 cm2 segments within the 1-foot pipe length. Values for AF are shown in Table 6. Therefore, to convert EffSOF to an overall Efficiency in the conventional survey units of cpm/dpm/100cm2, the EffSOF is multiplied by the AF to reflect the total activity within the 1-foot pipe length. The resulting Efficiency values are shown in Tables 6 and 7 for the Reactor Building and Other Buildings, respectively.

(100 2)

= x 100

3F1225-02 / Enclosure 13 / Page 15 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 14 Table 5 - Total Interior Area of 1-foot Pipe Segment Detector Pipe Interior Diameter (inches)

Area of 12-inch-long Pipe (cm2)

Area Factor (Area/100) 44-159-1 1

244 2.44 2

487 4.87 44-157 4

974 9.74 6

1,461 14.6 44-162 8

1,948 19.5 10 2,435 24.4 18 4,383 43.8 24 5,845 58.5 36 8,767 87.7 48 11,689 117 Table 6 - Detector Efficiencies for Pipes in the Reactor Building Detector Pipe Interior Diameter (inches)

EffSOF (cpm/dpm)

Efficiency (cpm/dpm/100cm2) 44-159-1 (1-inch Shell) 1 0.0039 9.62E-03 2

0.0039 1.92E-02 44-157 (3-inch Shell) 4 0.0081 7.93E-02 6

0.0081 1.19E-01 44-162 (7.5-inch Shell) 8 0.0141 2.74E-01 10 0.0141 3.43E-01 18 0.0141 6.17E-01 24 0.0141 8.23E-01 36 0.0141 1.23E+00 48 0.0141 1.65E+00 3F1225-02 / Enclosure 13 / Page 16 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 15 Table 7 - Detector Efficiencies for Pipes in BOP Detector Pipe Interior Diameter (inches)

EffSOF (cpm/dpm)

Efficiency (cpm/dpm/100cm2)44-159 (1-inch Shell) 1 0.0047 1.16E-02 2

0.0047 2.31E-02 44-157 (3-inch Shell) 4 0.0096 9.39E-02 6

0.0096 1.41E-01 44-162 (7.5-inch Shell) 8 0.0165 3.22E-01 10 0.0165 4.03E-01 18 0.0165 7.23E-01 24 0.0165 9.65E-01 36 0.0165 1.45E+00 48 0.0165 1.93E+00 6.3 Minimum Detectable Count Rate (MDCR)

Following NUREG-1507, the MDCR of a sample follows directly from the detection limit concepts. It is a level of radioactivity, either on the surface or within a volume of material, which is practically achievable by overall measurement process. The expression for MDCRstatic for cases in which background and sample are counted for different time intervals, may be given as follows for a NaI detector [8-4 and 8-5]:

=

3 + 3.29 x +x 1 + +

+

Where:

RB

= background count rate for count time (T)

TS+B

= measurement (sample) counting time (initially assumed to be 1 minute)

TB

= background counting time (initially assumed to be 10 minutes)

The background rates were established to be site-specific but will be reviewed periodically and revised as necessary. The MDCRstatic for the Models 44-159-1,44-157, and 44-162 with nominal background rates are presented in Table 8.

3F1225-02 / Enclosure 13 / Page 17 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 16 Table 8 - MDCR for Static Measurements Model Nominal

Background

(cpm)

TB (min)

TS+B (min)

MDCRstatic (cpm) 44-159-1 200 10 1

52 44-157 500 10 1

80 44-162 7000 10 1

292 Using the MDCR established for the detector in Table 9 and the Eff Factor from Section 6.1, calculate the MDC for the detector using the following equation:

MDC= MDCRStaticEfficiency Where the Efficiency is from Tables 6 and 7 and in units of cpm/dpm/100cm2. Table 9 presents the MDCs for the measurements for the Reactor Building and BOP pipes.

NOTE 5 The Eff Factors are based on a worst case geometry of the bottom of the piping a d distance from source to detector assuming a survey in 1-foot increments.

3F1225-02 / Enclosure 13 / Page 18 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 17 Table 9 - Minimum Detectable Concentrations Detector Pipe Interior Diameter (inches)

Reactor Building MDC (dpm/100 cm2)

BOP MDC (dpm/100 cm2)44-159 1

5,383 4,473 2

2,697 2,241 44-157 4

1,011 854 6

674 570 44-162 8

1,063 907 10 849 725 18 473 404 24 354 302 36 236 202 48 177 151 Similar calculations may be performed for pipe diameters not shown.

6.4 Concentrations at Measurement Locations To determine the net concentration at a measurement location, the following formula is used:

100 2=

Where RNET is the concentration determined at each measurement location. RGROSS is the gross count rate of the sample, and RB is the average background count rate.

The calculations represent commensurate and conservative gamma surface activities.

The gamma surface activity (RGROSS) for each FSS measurement is thus converted to a gamma measurement result (in units of dpm/100 cm2), and the average result per pipe is applied in compliance determination. Table 10 provides the net cpm equivalent to the applicable DCGL.

The formula could also be used to determine the gross count that would represent the DCGL:

= x +

Where DCGL has units of dpm/100 cm2, Efficiency has units of cpm/(dpm/100 cm2), and T is 1 minute in this application.

3F1225-02 / Enclosure 13 / Page 19 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 18 As an example, substituting data for the 44-157 in a 4-inch diameter pipe, the net cpm at the DCGL in the Reactor Building would be:

= 1.02 x 106

100 2 x 7.92 x 102 cpm/(dpm/100 2) x 1 + 500 1

= 81,300 ()

Table 10 - Net Detector Response Equivalent to Action Level for Buried Pipes Detector Pipe Interior Diameter (inches)

Reactor Building (net cpm)

BOP Buildings (net cpm)44-159 (1-inch Shell) 1 7.7E+04 9.2E+04 2

7.7E+04 9.2E+04 44-157 (3-inch Shell) 4 1.6E+05 1.9E+05 6

1.6E+05 1.9E+05 44-162 (7.5-inch Shell) 8 1.0E+06 3.2E+05 10 2.7E+05 3.2E+05 18 2.7E+05 3.2E+05 24 2.7E+05 3.2E+05 36 2.7E+05 3.2E+05 48 2.7E+05 3.2E+05 7.0 Field Application Guidance

1) Correlations have been developed for the radionuclide distributions for the Reactor Building and Other Buildings. It is recommended that one-minute readings be taken by centering the detector at the first foot and then every additional foot of pipe thereafter.
2) Prior to performing the radiological survey, confirm that the pipe has been visually inspected to ensure the pipe is free of debris, sediment, and water and is ready for the survey to be performed. Do not insert radiological detectors into areas of piping where video shows standing water, or where significant physical interferences exist that may damage the detector.

3)

Isolation and control measures are implemented to ensure that the final radiological and physical conditions of the interior surfaces of the pipe are not compromised and/or re-contaminated.

4)

Ensure the length of the cable between the detector and meter does not exceed the cable length used during the calibration.

5)

Detectors and meters should be calibrated as a pair. If it becomes necessary to use NOTE 6 Red guidance identifies personnel or equipment safety issue 3F1225-02 / Enclosure 13 / Page 20 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 19 a different meter, then a recalibration or source verification traceable to the original calibration is required.

6)

Survey instruments and camera cables should be wrapped to prevent contamination prior to inserting into known contaminated or potentially contaminated piping systems. This can include the sleeving of cables and rods and the application of tape to exposed detector surfaces but should not have an effect on the detector sensitivity to detect the residual activity.

7)

Do not use liquid decontamination solutions on exposed electrically energized equipment.

8)

Detectors may become saturated (levels exceeding full-scale response) when exposed to high activity. If a detector has become saturated during the performance of a survey, then a delay time may be necessary to allow the detector response to return to ground state.

9)

If a detector/meter pairing fails a pre-or post-use source response check, the FSS Engineering Supervisor must be notified. Do not perform the survey and repair the instrument. If the instrument fails the post-survey source check, the survey must be re-performed to ensure that quality FSS survey data is collected.

10) If a survey measurement taken on the interior of a buried pipe indicates radiological concentrations exceeds the Investigation Level of 75% of the applicable DCGL, then the FSS Engineering Supervisor is to be notified to determine the investigation actions.
11) Background values should be established prior to each buried pipe survey. This background value should be based on measurements for a similar pipe type, but a non-impacted one. A detector may be background checked in any diameter pipe made of the same material. Changing material (soil) compositions along a common buried line can cause larger variations in readings than typical for a common background soil composition. While this may help explain higher (or lower) measurements, it alone should not be used as a resolution for elevated measurements. Follow-up surveys, including smears and/or pipe/content samples, may be needed.

3F1225-02 / Enclosure 13 / Page 21 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 20 8.0 References 8-1 ADP CR3, 2025. Crystal River 3 License Termination Plan, Revision 4. December 2025.

8-2 Ludlum, 2021. Ludlum Model 44-157 & 44-159 & 44-159-1 & 44-162 Gamma Pipe Monitors. June 2021.

8-3 Groves, 2009. Microshield Version 8.02. Groves Software, Inc. 2009.

8-4 NUREG-1507, Revision 1, Minimum Detectable Concentrations with Typical Radiation Survey for Instruments for Various Contaminants and Field Conditions.

August 2020.

8-5 Cember, 1992. Introduction to Health Physics, 2nd Edition, Northwestern University, McGraw-Hill, Inc., 1992.

8-6 NRC 2023. Intermediate Staff Guidance (ISG), Radiological Survey and Dose Modeling of the Subsurface to Support License Termination. October.

8-7 NRC, 2022. NUREG-1757 Volume 2, Revision 2, Consolidated Decommissioning Guidance: Characterization, Survey, and Determination of Radiological Criteria -

Final Report (Revision 2), July 2022.

8-8 NUREG-1575, Rev. 1, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), EPA 402-R-97-016, Rev. 1, DOE/EH-0624, Rev. 1. NRC:

Washington, DC, U.S. Department of Defense, U.S. Department of Energy, U.S.

Environmental Protection Agency. 2000.

3F1225-02 / Enclosure 13 / Page 22 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 21 Attachment A - Calibration Source Certificate

<!Certf ff cate of <!Calibration Radioactive Material Exempt Quantity 10 CFR 30.18 This source has been calibrated with a HPGe detector for which the efficiency has been esta9lished the NIST traceable mixed nuclide standard SRS: 80899-854. The stated activity is I the weighted average of the measured gamma lines with an estimatei:J uncertainty of +/-5%.

The source is of sealed construction and wipe tested for surface contamination prior to shipping.

Customer:

Chesapeake Nuclear Services, Inc.

PO Number:

CC Radionuclide:

Cs-137 Half-Life:

30.07 years Decay Constant:

0.02305 years*1 Serial Number:

0707202 Calibration Date:

July 7, 2020 Activity:

10.000

µCi Photon Energy (keV) 661.7 Certified by: a.. *./J L, Daniel Sims, RPM 370,000 Bq Intensity(%)

85.1 Date:

Manufactured by:

Emission Rate (sec-1) 314,870 July 7, 2020 SPECTRUM TECHNIQUES, LLC.

106 Union Valley Road, Oak Ridge, TN 37830 Phone: 865.482.9937 Fax: 865.483.0473 Email: sales@spectrumtechniques.com www.spectrumtechniques.com 3F1225-02 / Enclosure 13 / Page 23 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e 24 Attachment B - Development of ERC and CPMR for Gamma Detectors 3F1225-02 / Enclosure 13 / Page 24 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-i Contents Relationship Between Detector Response and Radionuclide Concentration..................... 1 Count-rate-to-exposure-rate ratio (CPMR).................................................................. 1 Exposure-rate-to-concentration ratio (ERC)................................................................ 4 Determination of CPM per R/h for CsI Detector.......................................................... 5 Step 1: Calculate the Fluence Rate................................................................................ 6 Step 2: Calculate the Probability of Interaction................................................................. 6 Step 3: Calculate the Relative Detector.......................................................................... 7 Responses for Model 44-159-1 Detector................................................................................ 7 Responses for Model 44-157 Detector.................................................................................... 8 Responses for Model 44-162 Detector.................................................................................... 9 Figure Figure 1 Response of Gamma Energy for a 0.71x 0.71 CsI Scintillation Detector................... 2 Figure 2 Response of Gamma Energy for a 2 x 2 NaI Scintillation Detector............................ 2 Figure 3 Response of Gamma Energy for a 3 x 3 NaI Scintillation Detector............................ 3 Tables Table 1 Typical Relative Detector Response.............................................................................. 7 Table 2 ERC and CPMR Determination for Model 44-159-1 for Cs-137..................................... 7 Table 3 ERC and CPMR Determination for Model 44-159-1 for Co-60....................................... 8 Table 4 ERC and CPMR Determination for Model 44-157 for Cs-137........................................ 8 Table 5 ERC and CPMR Determination for Model 44-157 for Co-60.......................................... 9 Table 6 ERC and CPMR Determination for Model 44-162 for Cs-137........................................ 9 Table 7 ERC and CPMR Determination for Model 44-162 for Co-60.........................................10 Enclosures Microshield Report: Co-60 1-inch disk at three distances Microshield Report: Cs-137 1-inch disk at three distances 3F1225-02 / Enclosure 13 / Page 25 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-1 Relationship Between Detector Response and Radionuclide Concentration Count-rate-to-exposure-rate ratio (CPMR)

NUREG-1507 Figure 6-2 (reproduced here as Figure 2) presents an example of an energy dependence curve that illustrates how a 2-inch by 2-inch NaI scintillation detector responds (in cpm per microroentgen per hour [R/h]) depending on the incident gamma energy. For very low energies (e.g., about 10 kiloelectron Volt [keV] and less), the gamma may not penetrate the detectors metal housing. However, as the energies increase, the gamma is more likely to deposit all of its energy in the crystal, via the photoelectric effect, and create a pulse that the detector registers as a count. The detectors reach maximum efficiency when the gamma energies are in the 60 to 80 keV range. With still increasing gamma energies, interactions within the crystal are dominated by Compton scattering. These higher energy gammas may deposit only a fraction of their energy or may pass completely through the crystal without interaction; therefore, Figure 1 through 3 show a lower efficiency. To calculate the CPMR term, the relationship between the detector response and energy must be defined. The values illustrated in Figures 1, 2, and 3 are examples prepared for this TBD for the detector types and sizes involved which clearly show that cpm responses are different for each detector and gamma energy. A separate efficiency must be determined for energies from the radionuclides of concern, Co-60 and Cs-137. The mathematics are also complicated by fractional abundances of the radionuclides not being the same in the various buildings.

3F1225-02 / Enclosure 13 / Page 26 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-2 Figure 1 Response of Gamma Energy for a 0.71x 0.71 CsI Scintillation Detector Source: Fluence rates developed with National Institute of Standards and Technology (NIST) data, NUREG-1507 process [9-4]

Figure 2 Response of Gamma Energy for a 2 x 2 NaI Scintillation Detector Source: NUREG-1507, Table 6-3 [9-4]

1 10 100 1000 10000 100000 10 100 1000 10000 cpm/R/h Gamma Energy (keV) 0.71"x 0.71" CsI Detector 1

10 100 1,000 10,000 100,000 10 100 1000 10000 cpm/R/h Gamma Energy (keV) 2" x 2" NaI Detector let 3F1225-02 / Enclosure 13 / Page 27 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-3 Figure 3 Response of Gamma Energy for a 3 x 3 NaI Scintillation Detector Source: NUREG-1507, Table 6-3 [9-4]

Manufacturers typically provide a single value on this curve for a given detector (e.g.,

120 cpm/R/h for a 0.71-inch by 0.71-inch CsI; 900 cpm/R/h for a 2-inch by 2-inch NaI; and 2,300 cpm/R/h for a 3-inch by 3-inch NaI). In most cases, however, the CPMR is unknown and must be estimated. For example, the source, as in the contamination at CR3, contains both Cs-137 and Co-60. The following describes a method for estimating the CPMR for any combination of gamma-emitting radionuclides, starting with a simple hypothetical source that emits mono-energetic gamma radiation.

The CPMR for a single gamma energy may be determined in four steps. These steps are described below for a 2-inch by 2-inch NaI detector and a 400-keV gamma.

Step 1 is to estimate the fluence rate for the specific energy of interest:

Where:

(en/) is the mass energy absorption coefficient for air, and the value used is for 400 keV.

1 10 100 1,000 10,000 100,000 10 100 1000 10000 cpm/R/h Gamma Energy (keV) 3"x3" NaI 1 µR/ h

=

1 Fluence Rate= (Ey )(µenlP)air (400)(0.02949) = 0.08477 3F1225-02 / Enclosure 13 / Page 28 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-4 Step 2 is to estimate the probability of interaction within the detectors NaI crystal, assuming that the primary gamma interaction producing the detector response occurs through the end of the detector, as opposed to the sides:

where:

(/)NaI is the mass absorption coefficient for NaI (0.110 cm2/g at 400 keV) x is the thickness of the NaI (5.08 centimeters)

NaI is the density of NaI (3.67 g/cm3)

Step 3 is to estimate the relative detector response, which is the product of the fluence rate and probability of interaction:

Relative Response = Fluence Rate x P = 0.08477 x 0.871 = 0.0739 Steps 1, 2, and 3 are repeated for the energy with the known CPMR value (in this case, 662 keV with a CPMR of 900 cpm/R/h). The CPMR for a 662-keV gamma is estimated to be 0.0388.

Finally, Step 4 is to estimate the energy-specific CPMR (for 400 keV) by adjusting the known CPMR (for 662 keV) using calculated relative responses:

This is the simplest case, with just one gamma energy to consider. A weighted CPMR is required for mixed gamma fields, and this weighting involves using the exposure-rate-to-concentration ratio (ERC). Therefore, this attachment presents the weighted CPMR for mixed sources after describing the ERC term.

Exposure-rate-to-concentration ratio (ERC)

The ERC is traditionally generated by estimating the exposure rate in R/h at some distance from a source with a well-defined geometry and concentration. For this Technical Basis Document (TBD), Microshield is used to estimate the exposure rate at positions of 0.83 inches, 0.75 inches, and 2.25 inches above 1 picoCuries per square centimeter (pCi/cm2) of Cs-137 on a 1-inch diameter disk. These positions are selected because they relate to the scintillation crystal height above the source (i.e., the pipe interior) during pipe measurements.

The factors considered in the modeling include:

energy emissions from the radionuclide of interest (e.g., 662 keV for Cs-137) concentration of the radionuclide of interest (e.g., 1 pCi/cm2) areal dimensions of disk (e.g., radius = 0.5 inches) location of dose point (e.g., 0.83 inches, 0.75 inches, and 2.25 inches above the center)

Inherent shielding of detector casing (e.g., 0.05 inches thick of aluminum) p = 1 _ e - (µ/p)Na1(x)(PNa1) = 1 _ e - (0.110)(5.08)(3.67) = Q.871 CPMRioo = CPMRee2 x Relative Response400 = 900 x 0.0739== 1 700 cpm/µR/h Relative Response662 0.0388 3F1225-02 / Enclosure 13 / Page 29 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-5 Both Cs-137 and its short-lived progeny, barium (Ba)-137m, were chosen from the Microshield library. The source activity was selected based on a unit concentration of 1 pCi/cm2 and converted to the appropriate units required by the code:

(1 pCi/cm2) x (1 Ci/106 pCi) = 1.0E-6 Ci/ cm2 The modeling code performed the appropriate calculations and estimated the exposure rates (accounting for buildup) at the distances prescribed. Because unit concentrations were used, the ERC has units of R/h per pCi/cm2. Although the resulting gamma energy spectrum incident on the detector crystals (both primary and scattered gamma radiation) must be accounted for, the Microshield modeling code considered only primary gamma energies when evaluating the buildup from scattered photons. The detector response will be greater than the calculated detector response during field applications because the detector is more efficient at detecting lower energy scattered photons. NUREG-1507 claims that this is expected to yield a conservative determination of the detector response and resulting scan minimum detectable count (MDC) estimate.

The following are individual narratives regarding the Microshield simulations with ERC and CPMR derivations for each detector for the radionuclides of concern at CR3, both Co-60 and Cs-137.

The relative response of Co-60 to Cs-137 is simply the CPMRCo-60 to the CPMRCs-137. The two Microshield reports follow the narratives.

NUREG-1507 provides in its Table 6-3, values for cpm per microR/hour for each standard energy (keV) for both the 2-inch by 2-inch and 3-inch by 3-inch NaI detectors; however, the CsI detector was not discussed and is derived as follows.

Determination of CPM per R/h for CsI Detector To determine the relationship between the detectors net count rate and net exposure rate in cpm/R/h (MARSAME Section 7.11.4), there are three steps:

Calculate the fluence rate relative to the exposure rate (FRER) for the range of energies of interest.

Calculate the probability of interaction (P) between the radiation of interest and the detector.

Calculate the relative detector response (RDR) for each of the energies of interest.

For the NaI detectors, this process is detailed in NUREG-1507 and in its Table 6.3, NaI Scintillation Count Rate versus Exposure Rate (cpm per R/h). The cpm per microroentgen per hour are identified per energy level; however, the CsI detector is not evaluated, and the process is presented here as described in MARSAME, NUREG-1575, Supp. 1.

3F1225-02 / Enclosure 13 / Page 30 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-6 Step 1: Calculate the Fluence Rate The fluence rate, following NUREG-1507, is directly proportional to the exposure rate and inversely proportional to the incident photon energy and mass energy absorption coefficient:

Where:

= exposure rate (set equal to 1 R/hr for these calculations)

E

= energy of the gamma photon of concern (keV)

(en/)air = mass energy absorption coefficient in air at the gamma photon energy of concern (cm2/g)

The mass energy absorption coefficients in air are presented in the following table along with the calculated fluence rates (up to a constant of proportionality, since only the ratios of these values are used in subsequent calculations). Note that while the mass energy absorption coefficients in air, (en/)air, are tabulated values1, the selected energies are determined by the calculation of the detector response based on radionuclide concentration.

Step 2: Calculate the Probability of Interaction Assuming that the primary gamma interaction producing the detector response occurs through all sides of the detector, i.e., essentially within a 4 source, even if skewed, the probability of interaction (P) for a gamma may be calculated using the following Equation. The crystal is described as being 0.709 inches by 0.709 inches, which is a small crystal, and it is reasonable to assume that any photon striking from any direction has the same probability of interaction depending upon its energy.

Due to these assumptions, efficiencies may appear to be higher than those for a flat source.

= 1

()()

Where:

P

= probability of interaction (unitless)

(/)CsI = mass attenuation coefficient of 44-159-1CsI crystal at the energy of interest (e.g., 22.97 square centimeters per gram [cm2/g] at 40 keV) x

= thickness of the CsI crystal (1.8 centimeters [cm])

= density of the NaI crystal (4.51 grams per cubic centimeter [g/cm3])

The mass attenuation coefficients for the CsI crystal and the calculated probabilities for each of the energies of interest are presented in the Table.

1 https://www.physics.nist.gov/PhysRefData/XrayMassCoef/ComTab/cesium.html

  • 1 1

Fluence Rate(FRER ) oc X - ---

Er (P en f Pt;,

3F1225-02 / Enclosure 13 / Page 31 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-7 Step 3: Calculate the Relative Detector Response The RDR for each of the energies of interest is determined by multiplying the FRER by P. The results are presented in Table 1.

The cpm per R/h values are simple individual ratios of the RDRi to the 0.662 RDR multiplied by the cpm per R/h (120) of the 0.662 keV photon.

Table 1 Typical Relative Detector Response Energy (keV)

Mass Attenuation Coefficient -

Air (cm2/g)

FRER Mass Attenuation Coefficient -

CsI (cm2/g)

P RDR cpm per microR/hr 15 1.334 0.04998 54.86 1.00 0.0500 246 30 0.1537 0.21687 9.05 1.00 0.2169 1069 40 0.06833 0.36587 22.97 1.00 0.3659 1804 600 0.02953 0.05644 0.0837 0.49 0.0278 137 662 0.02931 0.05154 0.0787 0.47 0.0243 120 1000 0.02789 0.03586 0.0585 0.38 0.0136 67 1500 0.02547 0.02617 0.0464 0.31 0.0082 41 Highlighted value submitted by the manufacturer Responses for Model 44-159-1 Detector For the 1-inch disk and related 44-159-1 detector, based on the Microshield modeling and the assumed concentrations, the ERC ratios and the resulting CPMR for the distributions are presented in Tables 2 and 3.

Table 2 ERC and CPMR Determination for Model 44-159-1 for Cs-137 Energy (keV)

CPM per microR/hr 1 ERC 2

(µR/h per pCi/cm2)

CPMR 2 (cpm per

µR/h) 15 246 5.11E-06 3.78E-02 30 1069 2.70E-04 8.65E+00 40 1804 6.07E-05 3.28E+00 600 137 3.30E-02 1.36E+02 3.33E-02 148 1 Estimate is developed independently using NIST Data and NUREG-1507 process.

2 Developed through NUREG-1507 process.

3F1225-02 / Enclosure 13 / Page 32 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-8 Table 3 ERC and CPMR Determination for Model 44-159-1 for Co-60 Energy (keV)

CPM per microR/hr 1

ERC 2

(µR/h per pCi/cm2)

CPMR 2 (cpm per

µR/h) 600 137 6.32E-06 6.03E-03 1000 67 6.08E-02 2.82E+01 1500 41 8.32E-02 2.34E+01 1.44E-01 52 1 Estimate is developed independently using NIST Data and NUREG-1507 process.

2 Developed through NUREG-1507 process.

The relative response of Co-60 to Cs-137 is 52/148 = 0.35.

Microshield reports follow narratives.

Responses for Model 44-157 Detector For the 1-inch disk and related 44-157 detector, based on the Microshield modeling and the assumed concentrations, the ERC ratios and the resulting CPMR for the distributions are presented in Tables 4 and 5.

Table 4 ERC and CPMR Determination for Model 44-157 for Cs-137 Energy (keV)

CPM per microR/hr1 ERC2

(µR/h per pCi/cm2)

CPMR2 (cpm per

µR/h) 15 1160 2.51E-06 8.48E-01 30 5030 4.27E-05 6.27E+01 40 8480 7.23E-06 1.79E+01 600 1010 3.38E-03 9.95E+02 3.43E-03 1,076 1 Data provided in NUREG-1507 Table 6-3 2 Developed through NUREG-1507 process.

3F1225-02 / Enclosure 13 / Page 33 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-9 Table 5 ERC and CPMR Determination for Model 44-157 for Co-60 Energy (keV)

CPM per microR/hr1 ERC2

(µR/h per pCi/cm2)

CPMR2 (cpm per

µR/h) 600 1010 6.47E-07 4.43E-02 1000 550 6.23E-03 2.32E+02 1500 350 8.53E-03 2.02E+02 1.48E-02 434 1 Data provided in NUREG-1507 Table 6-3 2 Developed through NUREG-1507 process.

The relative response of Co-60 to Cs-137 is 434/1,076 = 0.40.

Microshield reports follow narratives.

Responses for Model 44-162 Detector For the 1-inch disk and related 44-162 detector, based on the Microshield modeling and the assumed concentrations, the ERC ratios and the resulting CPMR for the distributions are presented in Tables 6 and 7.

Table 6 ERC and CPMR Determination for Model 44-162 for Cs-137 Energy (keV)

CPM per microR/hr1 ERC2

(µR/h per pCi/cm2)

CPMR2 (cpm per

µR/h) 15 2,540 4.04E-07 2.28E+00 30 11,030 5.72E-06 1.40E+02 40 18,610 9.54E-07 3.95E+01 600 2,560 4.43E-04 2.52E+03 4.50E-04 2,702 1 Data provided in NUREG-1507 Table 6-3 2 Developed through NUREG-1507 process.

3F1225-02 / Enclosure 13 / Page 34 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-10 Table 7 ERC and CPMR Determination for Model 44-162 for Co-60 Energy (keV)

CPM per microR/hr1 ERC2

(µR/h per pCi/cm2)

CPMR2 (cpm per

µR/h) 600 2,560 8.48E-08 1.12E-01 1000 1,460 8.17E-04 6.16E+02 1500 970 1.12E-03 5.61E+02 1.94E-03 1,177 1 Data provided in NUREG-1507 Table 6-3 2 Developed through NUREG-1507 process.

The relative response of Co-60 to Cs-137 is 1,177/2,702 = 0.44.

Microshield reports follow narratives.

3F1225-02 / Enclosure 13 / Page 35 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-11 Case Summary of 1" Disk Page 1 of2 A

  1. 1
  1. 2
  1. 3 Date Filename MicroShield 8.02 Claude Wiblin (8.02-0000)

By Checked Co-60 1-inch disk at three distances Reactor.m sd Run Date May 17, 2024 Run Time Duration 3 25 08 PM 00 00 00 Case Title Descri2tion Geometry Project Info 1" Disk Co-60 With Al Shiel,:I_ for All Detectors to Crystal Edge 3 -Disk Source Dimensions Radius 1.27 cm (0.5 in)

Dose Points y

X y

z 0.2 11 cm (0.1 in) 0.0 cm (0 in) 0.0 cm (0 in) 1905 cm (0.8 in) 0 0 cm (0 in) 0 0 cm (0 in) 5.715 cm (23 in) 0 0 cm (0 in) 0 0 cm (0 in2_

z Shields X

Shield N Dimension l\\.1aterial Density Shield 1 Air Gap Nuclide Co-60

.05 in Aluminum 2.7 Air 0.00122 Source Input: Grouping l\\,iethod - Standard Indices Number of Groups: 25 Lower Energy Cutoff: 0.015 Photons< 0.015: Included Ci

µCilcm2

5. 0671e-012 Library: Grove Bq 1.8743e-001
1. 0000e-006 Buildup: The material reference is Shield 1 Integration Parameters Radial Circumferential

======-~--

Results - Dose Point # 1 - (0.083,0,0) in Bq/cm2 3.7000e-002 20 20 Fluence Rate FluenceRate Exposure Rate Exposure Rate Energy (l\\,ieV) Activity (Photons/sec) MeV/cm2/sec MeV/cm2/sec mR/hr mR/hr No Buildup With Buildup No Buildup With Buildup

0. 6 3 058e-05
3. 041 e-06
3. 240e-06
5. 936e-09 6323e-09 1.0 1.875e-01 1.875e-0l 3.750e-0l 3.156e-02 4.735e-02 7.942e-02 3.297e-02 4.942e-02 8.239e-02 Results - Dose Point# 2 - (0. 75,0,0) in 2-10 5.817e-05 3 0Sle-05 l.387e-04 6 077e-05 8315e-05 l.439e-04 file I/ IC/Program %20Fil es%20(x86)/11icroShi eldo/o 203/Exam ples/CaseFil es/HTML/Co-6..

SI 17 /2024 3F1225-02 / Enclosure 13 / Page 36 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-12 Case Summary of l" Disk Page 2 of2 Fluence Rate Fluence Rate Exposure Rate Exposure Rate Energy (MeV) Activity (Photons/sec) MeV/cm2/sec MeV/cm2/sec mR/hr mR/hr I

0.6 1 1.0 1.5 Totals r

3.058e-05 l.875e-0l l.875e-0l 3.750e-01 No Buildu.P With BuilduJ!.

No Buildup With Buildu 3.233e-07 3.314e-07 6.309e-10 6.469e-10 3.323e-03 5.007e-03 8.330e-03 3.38le-03 5.07le-03 8.452e-03 6.126e-06 8.423e-06 1.455e-05 6.233e-06 8.53 le-06 1.476e-05 Results - Dose Point# 3 - 2.25,0,0) in Fluence Rate Fluence Rate Exposure Rate Exposure Rate Energy (MeV) Activity (Photons/sec) MeV/cm2/sec MeV/cm2/sec mR/hr mR/hr

~

0.6 1 1.0 1.5 Totals 3.058e-05 l.875e-0l l.875e-01 3.750e-01 No Buildup With Buildup No Buildup With Buildup 4.245e-08 4.346e-08 8.286e-ll 8.483e-11 4.363e-04 6.57le-04 1.093e-03 2-11 4.434e-04 6.649e-04 1.108e-03 8.042e-07 l.106e-06 1.910e-06 8.l 73e-07 l.119e-06 1.936e-06 file:// IC :/Program%20Files%20( x86)/Micro Shield%208/Examples/CaseF iles/HTML/Co-6...

5/ l 7 /2024 3F1225-02 / Enclosure 13 / Page 37 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-13 Case Summary of 1" Disk Page 1 of2 A

  1. 1
  1. 2
  1. 3 Date Filename MicroShield 8.02 Claude Wiblin (8.02-0000)

By Checked Run Date Run Time Duration Cs-137 1-inch disk at three di stances Reactor.msd May 17, 2024 5 57 02 PM 00 00 00 Case Title D escri pti on Geometry Project Info 1" Disk Cs-137 With Al Shield for All Detectors to Crystal Edge 3 -Disk Source Dimensions Radius 1.27 cm (0.5 in)

Dose Points y

X y

z 0.2 11 cm (0.1 in) 0.0 cm (0 in) 0.0 cm (0 in) 1905 cm (0.8 in) 0 0 cm (0 in) 0 0 cm (0 in) 5.715 cm (23 in) 0 0 cm (0 in) 0 0 cm (0 in2_

z Shields X

Shield N Dimension l\\.1aterial Density Shield 1 Air Gap Nuclide Ba-137m Cs-137

.127 cm Aluminum 2.7 Air 0.00122 Source Input: Grouping M:ethod - Standard Indices Number of Groups: 25 Ci 4.7935e-0 12

5. 0671e-012 Lower Energy Cutoff: 0.015 Photons< 0.015: Included Library: Grove Bq 1.7736e-001
1. 8748e-00 1

µCi/cm*

9.4600e-007

1. 0000e-006 Buildup: The material reference is Shield 1 Integration Parameters Radial Circumferential Results - Dose Point# 1- (0.21082,0,0) cm Bq/cm*

3.5002e-002 3.7000e-002 20 20 Fluence Rate FluenceRate Exposure Rate Exposure Rate Energy (lV[eV) Activity (Photons/sec) lvleV/cm2/sec lvleV/cm2/sec mR/hr mR/hr No Buildup With Buildup No Buildup With Buildup 0015

1. 841 e-03
5. 656e-08
5. 956e-08
4. 851 e-09 5.109e-09 003 0.04 0.6 Totals 1.045e-02 2.465e-03 1.596e-0l

---l.743e--0l 2.288e-05 1.099e-05 1.587e-02 l.590e--02 2-12 2.720e-05 l.371e-05 1.690e-02 l.695e--02 2.268e-07 4.862e-08 3 097e-05 3.125e--05 2.696e-07 6 065e-08 3.300e-05 3.333e--05 file I/ IC/Program %20Fil es%20(x86)/11icroShiel d'/o 208/Exam ples/CaseFil es/HTML/Cs-1..

5/ l 7 /2024 3F1225-02 / Enclosure 13 / Page 38 of 39

ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 P a g e B-14 Case Summary of 1" Disk Page 2 of2 Results - Dose Point# 2 - 1.905,0,0 cm Fluence Rate Fluence Rate Exposure Rate Exposure Rate Energy (MeV) Activity (Photons/sec) MeV/cm2/sec MeV/cm2/sec mR/hr mR/hr f

0/01: t ~:~:!::~~

0.04 2.465e-03 0.6 1.596e-01 Totals 1.743e-01 No Buildu With Buildup No Buildup With Buildu 2.786e-08 2.922e-08 2.390e-09 2.506e-09 3.834e-06 1.471e-06 1.687e-03 1.692e-03 4.310e-06 1.635e-06 1.730e-03 1.736e-03 3.800e-08 6.507e-09 3.292e-06 3.339e-06 4.271e-08 7.232e-09 3.376e-06 3.428e-06 Results - Dose Point# 3 - (:i.715,0,0) cm Fluence Rate Fluence Rate Exposure Rate Exposure Rate Energy (MeV) Activity (Photons/sec) MeV/cm2/sec MeV/cm2/sec mR/hr mR/hr f

0.015 t 0.03 0.04 0.6 Totals 1.841e-03 1.045e-02 2.465e-03 1.596e-01 1.743e-01 No Buildup With Buildup No Buildup With Buildup 4.495e-09 4.704e-09 3.856e-10 4.035e-10 5.174e-07 1.956e-07 2.215e-04 2.223e-04 2-13 5.766e-07 2.157e-07 2.268e-04 2.276e-04 5.128e-09 8.650e-10 4.324e-07 4.388e-07 5.715e-09 9.541e-10 4.427e-07 4.497e-07 file:!/ IC :/Program%20Files%20(x86)/MicroShield%208/Examples/CaseFiles/HTML/Cs-1...

5/17/2024 3F1225-02 / Enclosure 13 / Page 39 of 39

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