ML25328A168

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Us Dept of Transportation - Nuclear Ship Savannah, Survey Unit Release Record Survey Unit STR-101-02 Containment Vessel (Cv) - 1st Level (Tanktop), Port Side
ML25328A168
Person / Time
Site: NS Savannah
Issue date: 11/20/2025
From: Roberson D
US Dept of Transportation, Maritime Admin, Nuclear Ship Support Services
To:
Office of Nuclear Reactor Regulation
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U.S. Department of Transportation Maritime Administration Office of Ship Operations Nuclear Ship Savannah Survey Unit Release Record Survey Unit STR-101-02 Containment Vessel (CV) - 1st Level (Tanktop ), Port Side Approved:

Senior Technical Advisor Prepared by:

Nuclear Ship Support Services, LLC

S AVANNAH Technical Staff Survey Unit Release Record PREPARED BY/ DATE:

PEER REVIEW / DATE:

DECOMMISSIONING PROGRAM MANAGER REVIEW/ DATE:

INDEPENDENT REVIEW /

DATE:

FSS MANAGER REVIEW/ DATE:

LICENSING and COMPLIANCE MANAGER REVIEW/ DATE:

SAFETY REVIEW COMMITTEE SUBMITTED/ APPROVED LICENSE TERMINATION PLAN MANAGER REVIEW/ DATE:

Survey Unit STR-101-02 l - - -- -- 1/2 Pi Digitally signed by D. Roberson D. Roberson Date:2025.03.1210:02:04

-05'00' Douglas Roberson Pete Hollenbeck Pete Hollenbeck, CHP Date Digitally signed by Pete Hollenbeck Date: 2025.03.12 11 :41 :36 -04'00' Date Soeuth Caleb Soeun DigitallysignedbySoeuthCalebSoeun Date: 2025.03.17 12:59:57 -04'00' Soeuth C. Soeun Date Digitally signed by James Reese, CHP, James Reese, CHP, RRPT RRPT Date: 2025.03.18 09:23:14 -07'00' James Reese Date Digitally signed by Daniel R.

Daniel R. Mihalik Mihalik Date: 2025.03.19 16:04:48 -04'00' Daniel Mihalik Date John Osborne ~~~ally signed by: John Osborne DN: CN = John Osborne LCM email LCM

= jmosborne@nsss.llc C = AD Date: 2025.03.28 17:21 :33 -05'00' John Osborne Date 3/19/2025 3/28/2025 Submitted Approved 9/2/2025 Eric Darois Date Page 2 of31 Containment Vessel (CV) - !st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record TABLE OF CONTENTS 1 -- -- ¥ h rt

1.

EXECUTIVE

SUMMARY

.................................................................................................... 6

2.

SURVEY UNIT DESCRIPTION.......................................................................................... 6

3.

CLASSIFICATION BASIS................................................................................................... 7

4.

DATA QUALITY OBJECTIVES......................................................................................... 7

5.

SURVEY DESIGN............................................................................................................... 11

6.

SURVEY IMPLEMENTATION......................................................................................... 13

7.

SURVEY RESULTS............................................................................................................. 14

8.

QUALITY CONTROL........................................................................................................ 16

9.

INVESTIGATIONS AND RESULTS................................................................................ 17

10. REMEDIATION AND RESULTS...................................................................................... 17
11. CHANGES FROM THE FINAL STATUS SURVEY PACKAGE................................. 17
12. DATA QUALITY ASSESSMENT...................................................................................... 17
13. ANOMALIES........................................................................................................................ 18
14. CONCLUSIONS................................................................................................................... 18
15. REFERENCES..................................................................................................................... 18
16. ATTACHMENTS................................................................................................................. 19 Survey Unit STR-101-02 Page 3 of31 Containment Vessel (CV) - 1st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record LIST OF TABLES l -- -- + hzi Table 4 Radionuclide Fractions and Normalized Fractions............................................... 8 Table 4 15 mrem/y DCGLs for ROC and Ni-63.................................................................. 9 Table 4 Re-normalized Co-60 and Cs-137 Fractions........................................................ 10 Table 4 Operational DCGLs................................................................................................ 10 Table 5 STR-101-02 Systematic Measurement Designations........................................... 12 Table 5 Scanning Coverage................................................................................................. 12 Table 5 Investigation Levels................................................................................................ 13 Table 7 Summary of Systematic, Judgmental, and QC Static Measurements................ 15 Table 7 Basic Statistical Properties of Static Measurement Population.......................... 15 Table 7 Scan Measurement Summary................................................................................ 16 Survey Unit STR-101-02 Page 4 of3 I Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record LIST OF ACRONYMS AND ABBREVIATIONS ALARA As Low As Reasonably Achievable CV Containment Vessel CR Contractor Report DQO Data Quality Objective DCGL Derived Concentration Guideline Level ETD Easy-to-Detect FSS Final Status Survey HSA Historical Site Assessment HTD Hard-to-Detect IC Insignificant Dose Contributors LBGR Lower Bound of the Gray Region LTP License Termination Plan MA RAD Maritime Administration MARLAP Multi-Agency Radiological Laboratory Analytical Protocols MARSSIM Multi-Agency Radiation Survey and Site Investigation Manual MDC Minimum Detectable Concentration NSS Nuclear Ship SAVANNAH QC Quality Control RASS Remedial Action Support Survey ROC Radionuclides of Concern TEDE Total Effective Dose Equivalent UBGR Upper Bound of the Gray Region VSP Visual Sample Plan Survey Unit STR-101-02 Containment Vessel (CV) - 1st Level (Tanktop), Port Side Page 5 of31

SAVANNAH Technical Staff Survey Unit Release Record

1.

EXECUTIVE

SUMMARY

This Survey Unit Release Record for survey unit STR-101-02, Containment Vessel (CV)

- 1st Level (Tanktop ), Port Side, has been generated in accordance with Maritime Administration (MARAD) procedure STS-005-035, Preparation of Survey Unit Release Records and FSS Final Reports, Reference (a) and satisfies the requirements of Section 5.10 of the Nuclear Ship SAVANNAH (NSS) License Termination Plan [L TP], STS-004-003, Revision 1, Reference (b ).

A Final Status Survey (FSS) survey package for this survey unit was developed in accordance with MARAD procedure STS-005-030, Preparation of Final Status Survey Packages, Reference (c), the NSS L TP, and with guidance from NUREG-1575, Revision 1, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSJM), Reference (d).

This survey unit has a MARSSlM classification of 1. A survey package was designed based upon the use of the Sign Test as the nonparametric statistical test for compliance. Both the Type I (a) and Type Il (P) decision error rates were set at 0.05. As a systematic measurement population, fifteen (15) static beta measurements were acquired from the survey unit. Two (2) judgmental static beta measurements were acquired as per the sample plan. In addition, four (4) judgmental static beta measurements were collected following the installation of new fiberglass grating in the space. Surface scanning was performed on 100% of the accessible total shell surface area in the survey unit. The data assessment results for survey unit STR-101-02 show that the maximum gross activity concentration among all the final systematic and judgmental measurements is equal to 24,488.08 dpm/100 cm2, which is 46.8% of the operational Derived Concentration Guideline Level (DCGLw) value of 52,300 dpm/100 cm 2. Therefore, the null hypothesis of the Sign Test is rejected, and survey unit STR-101-02 is acceptable for unrestricted use. The mean gross activity concentration among all the final systematic and judgmental measurements is equal to 5,182.90 dpm/100 cm2, which is 7.4% of the 15 mrem/y gross activity DCGLw of69,700 dpm/100 cm2. The mean gross activity concentration is equal to 1.12 mrem/y for the survey unit.

2.

SURVEY UNIT DESCRIPTION STR-101-02 is an impacted Class I survey unit. The CV I st level housed the reactor plant and some supporting systems. The reactor rested on a support ring on the CV I st level, and the entire CV rested on a cradle located on the tank top. The survey unit consists of the internal surfaces of the port side CY shell to the centerline. The 1st-level deck, shell, ring stiffeners, and reactor vessel foundation up to the 14-foot elevation are considered one and referred to as the CV shell. Based upon Computer Aided Design drawings, the 1st level port-side half to the centerline of the CV shell surface area is approximately 64.84 square Survey Unit STR-101-02 Page 6 of31 Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record meters (64.84 m2); this includes the shell surface above 2 meters. Refer to Attachment I of this report for figures and maps depicting survey unit STR-101-02.

3.

CLASSIFICATION BASIS Based on the NSS Historical Site Assessment [HSA], Reference (e), survey unit STR-101-02, identified as survey unit 101 A I in the HSA, was identified as a Class I structure survey unit. Primary coolant leaks were experienced from time to time, as was typical of nuclear power plants of the era. The coolant was released as steam condensed and drained to the bottom of the CV, from which it was collected in tank PD-T4, the containment drain tank.

In August of 1966, a leak produced low-level contamination in the CV that was decontaminated using a detergent solution. In 1968, a primary system leak from a pressure relief system isolation valve occurred. In 1969, a primary system leak from a control rod drive buffer seal was observed. On another occasion in 1969, 3,500 gallons leaked from a primary coolant pump vent pipe. Based upon a review of the historical information, the results of the characterization survey data, the 2024 Remedial Action Support Survey (RASS) STR-10 I-RASS-01-Rev 0, and the completion of a final Survey Unit Classification Worksheet, the correct final classification of survey unit STR-101-02 is Class 1.

4.

DATA QUALITY OBJECTIVES FSS planning and design relies on a properly executed Data Quality Objective (DQO) process to ensure, through compliance with explicitly defined inputs and boundaries, that the primary objective of the survey is satisfied. The DQO process is described in the NSS L TP. The appropriate design for a given survey was developed using the DQO process as outlined in STS-05-030, Reference (c).

The DQO process incorporated hypothesis testing and probabilistic sampling distributions to control decision errors during data analysis. Hypothesis testing is a process based on the scientific method that compares a baseline condition to an alternate condition. The baseline condition is technically known as the null hypothesis. Hypothesis testing rests on the premise that the null hypothesis is true, and that sufficient evidence must be provided for rejection. In designing the survey package, the underlying assumption, or null hypothesis was that residual activity in the survey unit exceeded the release criteria. Rejection of the null hypothesis would indicate that residual activity within the survey unit does not exceed the release criteria. Therefore, the survey unit would satisfy the primary objective of the FSS sample plan.

The primary objective of the FSS sample plan is to demonstrate that the level of residual radioactivity in survey unit STR-101-02 does not exceed the release criteria specified in the L TP and that the potential dose from residual radioactivity is As Low As Reasonably Achievable (ALARA).

Survey Unit STR-101-02 Page 7 of31 Containment Vessel (CV) - 1st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record l - - -- a i rt MARAD Contractor Report (CR)-139, Calculations to Support NSS Surface Contamination DCGLs, Reference (f) established the basis for an initial suite of potential Radionuclides of Concern (ROC) for decommissioning. Insignificant dose contributors (IC) were determined consistent with the guidance contained in Section 3.3 of NUREG-

1757, Volume 2,

Revision 1,

Consolidated Decommissioning Guidance Characterization, Survey, and Determination of Radiological Criteria, Reference (g). In all analyses, Cs-137 and Co-60 contribute nearly I 00% of the total dose. The remaining radionuclides were designated as IC. Because Ni-63 comprises approximately 90% of the total activity, it is accounted for as a surrogate to Co-60. Therefore, the final ROCs for final status surveys are Cs-13 7 and Co-60surrogate-L TP Chapter 6, Section 6.13 discusses the process used to derive the ROC for the decommissioning of the NSS, including the elimination of insignificant dose contributors from the initial suite. Table 4-1 presents the initial suite of ROC for the decommissioning of the NSS, and the normalized mixture fractions based on the radionuclide mixture.

Table 4 Radionuclide Fractions and Normalized Fractions Normalized Sum of Sum of Only Co, Ni Nuclide Fractions Fractions and Cs C-14 3.37E-02 5.61E-03 Co-60 9.78E-02 l.63E-02 l.63E-02 Ni-63 5.40E+00 9.00E-01 9.00E-01 Sr-90 9.22E-06 l.54E-06 Tc-99 l.27E-04 2.11 E-05 Ag-108m 8.30E-04 1.38E-04 Cs-137 4.57E-0l 7.61E-02 7.61E-02 H-3 1.93E-03 3.21E-04 Fe-55 8.l0E-03 l.35E-03 Am-241 5.79E-07 9.66E-08 Pu-239/240 4.81E-07 8.0lE-08 Totals 6.00E+00 l.00E+00 9.93E-01 Each radionuclide-specific DCGLw is equivalent to the level of residual radioactivity (above background levels) that could, when considered independently, result in a Total Effective Dose Equivalent (TEDE) of 15 mrem/yr to an Average Member of the Critical Group. Table 4-2 on the next page presents the 15 mrem/y DCGLw for Co-60, Ni-63 and Cs-13 7 from Chapter 6 of the L TP.

Survey Unit STR-101-02 Page 8 of31 Containment Vessel (CV) - 1st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record Table 4 15 mrem/y DCGLs for ROC and Ni-63 Radionuclide DCGLw (dpm/100cm2)

Co-60 2.37E+04 Ni-63 2.53E+08 Cs-I 37 1.20E+05 Nickel-63 is a Hard-to-Detect (HTD) radionuclide. To account for Ni-63, the Easy-to-Detect (ETD) radionuclide Co-60 will be used as a surrogate.

The surrogate DCGL is computed as:

DCGL DCGLETD X DCGLHTD surrogate =

(f HTD:ETDXDCGLETv)+ DCGLHTD Equation I Where:

DCGLErn = the DCGL for the easy-to-detect radionuclide DCGLHTo the DCGL for the hard-to-detect radionuclide FHTo:ETD the activity ratio of the hard-to-detect radionuclide to the easy-to-detect radionuclide Using the data in Table 4-1, the Ni-63/Co-60 ratio equals 55.3. Solving Equation 1 using the DCGLs for Co-60 and Ni-63 in Table 4-2 and the Ni-63/Co-60 ratio of 55.3 is shown below.

DCGLco-60 surrogate= 2.37E + 04 X (

2*53E+~B

= 2.36E+04 dpm/100 cm2 55.3 X 2.37E+04 +2.53E+08 A gross activity DCGLw has been established, based on the representative radionuclide mix, as follows:

Where:

n DCGLn Gross Activity DCGLw =

1

= fraction of the total activity contributed by radionuclide n

= the number of radionuclides

= DCGL for the ROC Equation 2 Of the three radionuclides, only Co-60 and Cs-137 can be detected by gross activity measurements. The normalized fractions for both radionuclides in Table 4-1 must be re-normalized for use in Equation 2. Table 4-3 on the next page presents the re-normalized fractions for each radionuclide.

Survey Unit STR-101-02 Page 9 of31 Containment Vessel (CV) - 1st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record Table 4-3-Re-normalized Co-60 and Cs-137 Fractions Normalized Only Co-60 Re-sum of and Cs-137 normalized Nuclide fractions Fractions Fractions C-14 5.61E-03 Co-60 l.63E-02 1.63E-02 1.76E-0l Ni-63 9.00E-01 Sr-90 l.54E-06 Tc-99 2.llE-05 Ag-108m l.38E-04 Cs-137 7.61E-02 7.61E-02 8.24E-01 H-3 3.21E-04 Fe-55 l.35E-03 Am-241 9.66E-08 Pu-239/240 8.0lE-08 Totals 1.00E+00 9.24E-02 1.00E+00 Solving Equation 2, using the re-normalized Co-60 and Cs-137 fractions and the Co-60 surrogate DCGL, is shown below.

1 Gross Activity DCGLw = 1_76E-l 8_24E-l = 6.97E+04 dpm/100 cm2.

2.36E+o4 + 1.20E+os The DCGLs are reduced to a fraction of the 15 mrem/yr dose limit. The reduced DCGLs, or operational DCGLw, is then used as the DCGL for the FSS design of the survey unit (investigations levels, etc.). The operational DCGLs are set at 75% of the 15 mrem/y DCGLw. The operational DCGLs are provided in Table 4-4.

Table 4 Operational DCGLs Radionuclide Operational DCGLw (dpm/100cm2)

Co-60 1.77E+04 Cs-137 9.00E+04 Gross Activity 5.23E+04 Instrument DQOs included a verification of the ability of the survey instrument to detect the radiation(s) of interest relative to the operational DCGLw. Survey instrument response checks were required prior to issuance and after the instrument had been used. Control and accountability of survey instruments was required to ensure the quality and prevent the loss of data. STS-05-030, Reference (c) states that a Minimum Detectable Concentration (MDC) below l 0% of the DCGL is preferable and up to 50% is acceptable. Because the Survey Unit STR-101-02 Page 10 of3 I Containment Vessel (CV) - 1st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record background is low on the NSS, the MDCs for most static and scan measurements were less than 10% of the DCGL and in all cases the MDCs were less than 50% of the DCGL.

5.

SURVEY DESIGN The L TP specifies that the Sign Test will be used as the nonparametric statistical test for compliance with the release criteria. The number of measurements for use with the Sign Test was determined in accordance with MARAD procedure STS-005-031, Calculation of the Number of Measurements for Final Status Surveys, Reference (h). The relative shift for the survey unit data set is defined as shift (~), which is the Upper Boundary of the Gray Region (UBGR), or the operational DCGLw, minus the Lower Bound of the Gray Region (LBGR), divided by sigma (er), which is the standard deviation of the data set used for survey design. The optimal value for the relative shift should range between one (I) and three (3). If the relative shift is less than one (I), or greater than three (3), then the value of two (2) will be used for the relative shift.

A RASS survey of the CV I51 level was performed on April 9, 2024 and a scoping survey of the Neutron Shield Tank footprint was performed on April 20, 2023. A total of forty-four (44) static measurements and 50 smears were collected. Only nine (9) smears had positive alpha activity at 4.21 dpm/100 cm2. The maximum beta activity was 305.20 dpm/100 cm2. The average total surface activity concentration and standard deviation of the measurements was 6,868 and 9,907 dpm/100 cm2, respectively. Because the activity concentration is low, the LBGR was set to half the operational DCGLw. The relative shift for survey unit STR-101-02 is based upon the RASS survey results and was calculated as follows:

52,300-26,150 Relative Shift (!1/cr) = ------ = 2.64 9,907 Since the calculated relative shift fell between the optimal values of l and 3 no adjustment was required placing the relative shift at 2.64. Both the Type I error, or a value, and the Type II error, or~ value, were set at 0.05. The sample size from STS-05-031, Reference (h) that equates to the Type I and Type II error of 0.05 for use with the Sign Test is a minimum number of fixed measurements value of fifteen (15). Fifteen (15) total systematic measurements were used in the survey design for survey unit STR-101-02.

The survey unit was designated Class 1; therefore, the measurement locations were selected based on a systematic grid with a random starting point. The systematic locations of the static measurements were selected using Visual Sample Plan (VSP). Input parameters included the use of survey unit drawings, and the systematic sampling tool set with a predetermined number of measurement locations. The systematic measurement locations were identified in the field using dimension parameters provided on the survey unit map (see Attachment I). Table 5-1 on the next page lists the systematic measurements to be collected for FSS of survey unit STR-101-02.

Survey Unit STR-101-02 Page 11 of3 l Containment Vessel (CY) - 1st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record l - - -- d i 1 Table 5 STR-101-02 Systematic Measurement Designations Label LX(m)

LY(m)

Surface STR-101-02-01 1.10 0.29 CV Shell STR-101-02-02 3.61 0.29 CV Shell STR-101-02-03 6.11 0.29 CV Shell STR-101-02-04 8.61 0.29 CV Shell STR-101-02-05 11.12 0.29 CV Shell STR-101-02-06 13.62 0.29 CV Shell STR-101-02-07 2.36 2.45 CV Shell STR-101-02-08 4.86 2.45 CV Shell STR-101-02-09 7.36 2.45 CV Shell STR-101-02-10 9.87 2.45 CV Shell STR-101-02-11 12.37 2.45 CV Shell STR-101-02-12 3.61 4.62 CV Shell STR-101-02-13 6.11 4.62 CV Shell STR-101-02-14 8.61 4.62 CV Shell STR-101-02-15 11.12 4.62 CV Shell The implementation of Quality Control (QC) measures is referenced in LTP Chapter 5, Section 5.11. A randomly chosen replicate measurement was specified in the survey package. This measurement was to be collected by either a different technician or by a different instrument. Location STR-101-02-07 was chosen for the replicate measurement.

In addition, the survey package also specified to perform QC operability checks of field instruments both prior to and after collection of the measurements.

The survey package also specified collection of two (2) judgmental measurements to augment the systematic measurements. The locations of these two measurements were to be determined by the technicians or the field supervisor. Those two judgmental measurements are identified as STR-101-02-16-J and STR-101-02-17-J. Those locations are documented on the field forms.

For this Class I structure survey unit, the "Scanning Coverage" are those levels specified in L TP Chapter 5, Table 5-3, and are reproduced below in Table 5-2.

Table 5 Scanning Coverage Classification Required Scanning Coverage Fraction Class l 100%

For survey unit STR-101-02, a single scan area was established. The survey package stated to scan 100% of the accessible area in each scan area. Refer to Attachment 1 for figures and maps depicting the measurement and scan locations in survey unit STR-101-02.

Survey Unit STR-101-02 Page 12 of3 l Containment Vessel (CV) - 1st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record For this Class 1 structure survey unit, the "Investigation Levels" for direct and scanning measurement results are those levels specified in L TP Chapter 5, Table 5-2, and are reproduced below in Table 5-3.

Table 5 Investigation Levels Survey Unit Fixed Measurements Scan Measurements Classification Class I

> Operational DCGLw

> Operational DCGLw These investigation levels were specified in the survey package.

An additional action level was specified in the survey package. If the technician observed a count rate of2,500 cpm when scanning, approximately one-half of the investigation level, they were to stop scanning, backup and rescan the elevated location again to see if the count rate was observed again. If observed again, an additional static measurement would be collected. If not, they would continue scanning.

6.

SURVEY IMPLEMENTATION For survey unit STR-101-02, compliance with the unrestricted use criteria was demonstrated through a combination of surface scanning and surface static measurements with a Ludlum Model 43-93 ZnS detector connected to a Ludlum Model 3002 meter operating in the beta mode. Surface scans were also performed utilizing the Ludlum 43-37 large area gas proportional detector connected to a Ludlum 3002 operating in beta mode.

Prior to performing the survey, a walkdown of the survey unit was performed per MARAD procedure STS-005-032, Survey Unit Turnover and Control, Reference (i). No conditions prohibited the proper collection of static and scan measurements.

FSS field activities were conducted under the approved FSS Package Number NSS-FSSP-STR-101-02-00-00, which included DQOs, survey design, detailed FSS instructions, survey maps and survey forms. FSS field activities were projected to take four (4) working days to complete. A daily briefing was conducted to discuss the expectations for job performance and to review the safety aspects of the job. An FSS package "Field Log" was used to document field activities and other information pertaining to the performance of the FSS. The FSS field activities took two (2) days to complete and were performed on July 15, 2024, and July 16, 2024. On July 23, 2024, a single static measurement was collected at the location of an elevated scan measurement in SA-01, identified as SA 01.

An ambient background count rate was collected by taking a I-minute static measurement, while maintaining the detector waist high. This value was used to calculate the MDC for scanning and static measurements.

Survey Unit STR-101-02 Page 13 of3 l Containment Vessel (CV) - !st Level (Tanktop), Port Side

SAVANNAH Technical Staff Survey Unit Release Record

- -- J t The fifteen ( 15) systematic static measurement locations were marked based on the dimensions provided on the survey map. Two (2) judgmental measurement locations were selected and marked as per the sample plan. A ] -minute static measurement was acquired at each location with the detector in contact with the surface.

The entire scan area, SA-01, was scanned, resulting in 100% of the total shell surface area being scanned. The total scan area meets the scan coverage requirements for a Class 1 area as shown in L TP Table 5-3 and reproduced in Table 5-2 of this release record. Scanning was performed with the detector held approximately 0.75 inches from the surface while moving at a speed of one detector width per second.

Following the RASS of the CV 1st level (Tank Top) and just prior to the FSS, new fiberglass grating was installed on the curvature walking surfaces of the CV shell. Because of this new grating, a second scan area was created, SA-02. Judgmental scanning in SA-02-J was performed on the new grating. Four additional judgmental statics, STR-101 18-J through STR-101-02-21-J, were added, capturing the new fiberglass grating.

The implementation of survey specific QC measures included the collection of one (1) replicate static measurement. The random location of the replicate measurement was STR-101-02-07 and identified as STR-101-02-07-D. That measurement was collected with a different instrument but the same make and model used for the original measurement.

The instruments used for this survey were satisfactorily checked prior to and after performing the survey.

7.

SURVEY RESULTS The efficiencies used to convert count rates to activity are weighted efficiencies in which the Tc-99 (Co-60 surrogate) and Cs-137 efficiencies are weighted by the fraction Co-60 and Cs-137 comprise the NSS fingerprint. This is documented in CR-164, Reference U).

For example, (derived from NUREG-1507) if the 41t contact Tc-99 efficiency is 0.1002 c/d and the 41t Cs-137 contact efficiency is 0.1868 c/d, the weighted contact efficiency is shown below.

Weighted efficiency (c/d) = (0.1002) (0.176) + (0.1868) (0.824) = 0.1716 c/d Copies of the instrument calibration records are presented in Attachment 2.

The highest ambient background count rate from a ]-minute count was 99 cpm. Rounding up the count rate to I 00 cpm, using the painted surface contact detector weighted efficiency of 0.0858 c/d or the fiberglass grate contact detector weighted efficiency of 0.0159 c/d and using LTP Equation 5-6 (derived from NUREG-1507), in which the count time and background count times are equal, results in an MDC for I-minute static measurement equal to 577 dpm/100 cm2 with the (15) density painted surface. This value is 1. 1 % of the operational DCGLw and less than I% of the gross activity DCGLw. The resulting MDC with the (0) density fiberglass grate surface is 3, 119 dpm/100cm2. This value is 6.0% of Survey Unit STR-101-02 Page 14 of31 Containment Vessel (CV) - 1st Level (Tanktop), Port Side

SAVANNAHTechnical Staff Survey Unit Release Record the operational DCGLw and 4.5% of the gross activity DCGLw. Table 7-1 presents the activity concentration for all final static measurements.

Table 7 Summary of Systematic, Judgmental, and QC Static Measurements Activity Concentration Measurement ID (dpm/100 cm2)

STR-101-02-01 1725.83 STR-101-02-02 1585.89 STR-101-02-03 2530.44 STR-101-02-04 1084.47 STR-101-02-05 9725.27 STR-101-02-06 7229.81 STR-101-02-07 1609.22 STR-101-02-08 1364.34 STR-101-02-09 1247.73 STR-101-02-10 3381.69 STR-101-02-11 2110.64 STR-101-02-12 1376.00 STR-101-02-13 2133.96 STR-101-02-14 1271.05 STR-101-02-15 1399.32 STR-101-02-16-J 24488.08 STR-101-02-17-J 2297.22 STR-101-02-18-J 13295.19 STR-101-02-19-J 12539.07 STR-101-02-20-J 10207.68 STR-101-02-21-J 6238.03 STR-101-02-07-O 771.73 The raw static data with detector efficiencies are presented in Attachment 3.

Table 7-2 presents the basic statistical properties of all the final static measurement population, without the duplicate measurement.

Table 7 Basic Statistical Properties of Static Measurement Population Parameter Value Units Minimum Measurement 1084.47 dpm/100 cm2 Maximum Measurement 24488.08 dpm/100 cm2 Mean 5182.90 dpm/100 cm2 Median 2133.96 dpm/100 cm2 Standard Deviation 5957.24 dpm/100 cm2 Coefficient of Variation 1.15 unitless Residual activity dose rate 1.12 mrem/y The mean activity from static measurements was divided by the gross activity DCGLw to derive a mean fraction. The mean fraction was then multiplied by 15 mrem/yr to derive the Survey Unit STR-101-02 Page 15 of3 l Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record l - - -- + b rt dose attributed to the survey unit. For survey unit STR-101-02, the calculated dose from residual activity is 1.12 mrem/yr. Review of the Table 7-1 and Table 7-2 data shows that the values for the mean, standard deviation, coefficient of variation and the residual activity dose rate are biased high due to the four judgmental static measurements on the new grating. These four values are high because of the low efficiency. See Attachment 3 for the values of the efficiency.

The scan MDC for the Ludlum 43-37 detector was calculated using the rounded count rate of250 cpm, the detector weighted efficiency of0.0802 c/d at a distance of 0.75 inches and using LTP Equation 5-8 (derived from NUREG-1507). The elevated area was assumed to be a 100 cm2 circular source. The detector width is 6.25 inches, and thus the detector speed is 6.25 in/second. With these parameters, the resulting observation interval is 0.711 seconds. The resulting MDC for scanning is 604 dpm/100 cm2. This value is less than 1.2%

of the operational DCGLw and less than 1 % of the gross activity DCGLw.

The scan MDC for the Ludlum 43-93 detector was calculated using the highest rounded count rate of 100 cpm, the detector weighted efficiency of 0.0632 c/d at a distance of 0.75 inches and using LTP Equation 5-8 (derived from NUREG-1507). The elevated area was assumed to be a l 00 cm2 circular source. The detector width is 3.6 inches, and thus the detector speed is 3.6 in/second. With these parameters, the resulting observation interval is 1.234 seconds. The resulting MDC for scanning is 2,154 dpm/100 cm 2. This value is 4.1 %

of the operational DCGLw and 3.1 % of the gross activity DCGLw.

Table 7-3 presents activity concentrations for all scan measurements.

Table 7 Scan Measurement Summary Low to High Range Average Scan ID d m/100 cm2 (dpm/100 cm2)

SA-01 426.93 - 66484.52 33455.73

---+---------i SA-02-J 5440.93 - 15545.51 10493.22 The raw scan data with detector efficiencies are presented in Attachment 3.

One (l) static measurement was collected on July 23, 2024, in SA-01 due to a positive indication during scanning which triggered the 2,500 cpm action level. This condition was observed when performing preliminary data review. The follow-up static measurement SA-01-01 resulted in an activity concentration of 50,725 (dpm/100 cm2) which is below the investigation level.

8.

QUALITY CONTROL The implementation of survey specific QC measures included the collection of one (I) replicate static measurement (STR-101-02-07-D) for analysis. The acceptance criteria for replicate static measurements is defined by NUREG-1576, Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP) Volume 1, Appendix C, Section Survey Unit STR-101-02 Page 16 of31 Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record l - - -- t -k rl C.4.2.2 Duplicate Analyses, Reference (k). That section states that when the average of the two measurements is less than the UBGR, the control limit for the absolute difference between the two values is 4.24µMR-The required method uncertainty (µMR) is a control limit formula value that is equal to the shift divided by ten (I 0). The shift is equal to the operational DCGLw, minus one half the operational DCGLw, or 26,150 dpm/100 cm2.

Therefore, the control limit is equal to 11,087.6 dpm/100 cm2, as shown below.

Control limit= 26, 150/10*4.24 = 11,087.6 dpm/100 cm2.

The results of the evaluation of the QC measurement show agreement between the original and duplicate measurements. See Attachment 4 for the results.

9.

INVESTIGATIONS AND RESULTS On 7/15/2025, one (I) static location triggered the Investigation level of 52,300 dpm/100 cm2. That location was identified as STR-101-02-16-J at 1.49E+05 dpm/100cm2. The surface area was a localized spot on the shell's curvature.

10.

REMEDIATION AND RESULTS Remediation was performed at that location. The post remediation survey result is 2.44E+04 dpm/100 cm2. This value is less than the operational DCGLw and is presented in Table 7-1.

11.

CHANGES FROM THE FINAL STATUS SURVEY PACKAGE There were no addendums to the FSS package which was developed in accordance with STS-005-030.

A field change was initiated to the FSS package. As described in Section 6, a separate scan area, SA-02-J, was created for the new fiberglass grating. Four additional judgmental static measurements, STR-101-02-18-J through STR-101-02-21-J, were added and collected on the fiberglass grating.

12.

DATA QUALITY ASSESSMENT The DQO sample design and data were reviewed in accordance with MARAD procedure STS-005-033, Final Status Survey Data Assessment and Investigation, Reference (I) for completeness and consistency. Documentation was complete and legible. Scan surveys and the collection of static measurements were consistent with the DQOs and were sufficient to ensure that the survey unit was properly designated as Class 1.

The preliminary data review consisted ofcalculating basic statistical quantities (e.g., mean, median, standard deviation). The mean and median values of the data were well below the operational DCGLw. The survey unit data is presented graphically in a frequency plot and quantile plot presented in Attachment 6.

Survey Unit STR-101-02 Page 17 of3 I Containment Vessel (CV) - 1st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record 1 - -- d 1 zi All fifteen systematic/unbiased measurements did not require remediation and were less than the DCGLw. Although MARSSIM states that the Sign Test need not be performed in the instance that no measurements exceed the DCGLw, the test was conducted to demonstrate coherence to the statistical principles of the DQO process. The Sign Test was performed on the data and compared to the original assumptions of the DQOs. The evaluation of the Sign Test results clearly demonstrates that the survey unit passes the unrestricted use criteria, thus, the null hypothesis is rejected. The results of the Sign Test are presented in Attachment 5.

13.

ANOMALIES No anomalies were observed during the performance of the survey.

14.

CONCLUSIONS

15.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

Survey unit STR-101-02 has met the DQOs of the FSS package. The survey unit is properly classified as Class 1.

All final measurements are less than the DCGLw. The sample data passed the Sign Test.

The null hypothesis was rejected. Therefore, the survey unit meets the release criteria.

The dose contribution from residual activity in survey unit STR-101-02 is 1.12 mrem/yr TEPE, based on the mean activity of all the final measurements.

Survey unit STR-101-02 is acceptable for unrestricted use.

REFERENCES STS-005-035, Preparation of Survey Unit Release Records and FSS Final Reports.

STS-004-003, N.S. SAVANNAH License Termination Plan, Revision 1.

STS-005-030, Preparation of Final Status Survey Packages.

NUREG-1575, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), Revision 1, August 2000.

CR-003, STS-109, Historical Site Assessment, Revision 1, 2023.

CR-139, TSO 21-089, Calculations to Support NSS Surface Contamination DCGLs, Revision 1, September 2022.

NUREG-1757, Vol 2, Rev 1, Characterization, Survey, and Determination of Radiological Criteria.

STS-005-031, Calculation of the Number of Measurements for Final Status Surveys.

STS-005-032, Survey Unit Turnover and Control.

Survey Unit STR-101-02 Page 18 of3 l Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record l - -

-- a

  • i rt (j)

(k)

(I)

16.

CR-164, TSD 23-126, Calculation o,fWeighted Efficiencies and MDCs of Ludlum Detectors for Final Status Surveys on the NS SAVANNAH, Rev 0 I.

NUREG-1576, Multi-Agency Radiological Laboratory Analytical Protocols Manual, (MARLAP), July 2004.

STS-005-033, Final Status Survey Data Assessment and Investigation.

ATTACHMENTS Attachment I - Figures and Maps - Calibration Records - Static and Scan Data - Quality Control Assessment - Sign Test - Graphical Presentations Survey Unit STR-101-02 Page 19 of31 Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record I

l Survey Unit STR-101 -02 - Figures and Maps Location of the Containment Vessel (CV) - 1st Level (Tanktop) i I t

\\ "

1,1 0 I} ~

I

.. I *

  • I
  • im_ flO

.Lt Containment Vessel (CY) - I st Level (Tank top), Port Side Page 20 of3 I

SAVANNAH Technical Staff Survey Unit Release Record Containment Vessel (CV) - 1st Level (Tanktop) Port Side Systematic and Judgmental Static Locations NSS-FSSP-STR-101-02

$-STR-101-02* 12

-Ej,STR-t0t-02-07 125 120 LEGEND Survey Unit STR-101-02

~ -. ---

E!#TR-101-02-10

$-STR-101-02-03 VSP Origin Point in Ship Coordinates:

2'0" Aft of Frame 121 On Centerline I 3' IO" above baseline NOTE CV SHELL SHOWN IN FLATTENED Vlf\\l (S lo 14')

SAMPlE LOCATIONS CREA TED IN VISUAL SAMPLE PLAN NUMBER Of SAMPLES 15 PLACEMENT METHOD SYSTEMATIC START LOC RANDOM Containment Vessel (CV) - I st Level (Tanktop), Port Side 105 100 BOW tr Page2 1 of31

SA VANNAH Technical Staff Survey Unit Release Record Containment Vessel (CV)- 1st Level (Tanktop) Port Side Scan Areas NSS-FSSP-STR-101-02 NOTE:

Shell curvature was flattened out for sampling placement purposes.

I Point of Origin, located on the AFT end of CV on centerline and just under the 2nd level at 14-foot elevation.

Survey Unit STR-10 1-02 Containment Vessel (CV) - !st Level (Tanktop), Port Side I

I SA-01 I

\\

\\

I I

I I

I I

/

I I

/

BOW b t

Page 22 of3 l

SAVANNAH Technical Staff Survey Unit Release Record

-J* - --- - r r1 - Calibration Records Calibration Certificate - ID Number: 25035113000 - 20240131 - 0 RSCS customer. MattllewG Hunter Rad ation Safety & COntrol Serv1ces, Inc.

93 Ledge Road Seabrook NH 0387 4 Test I I

Test2 I

5.01 kcpm I

4.99 kcpm I

Range Target Value AUTO 500 Kcpm#

AUTO 50Kcpm#

AUTO 5 Kcpm#

AUTO 0.5 KCDm#

Instrument Ludlum Model 3002 Probe Model Ludlum 43-37 Precision Check Test3 I

Mean 5.00 kcpm I

5.00 kcpm Accuracy Check As Found As Left 500Kcpm#

500Kcpm#

49 9 Kcpm#

49 9Kcpm*

5.0 1 Kcpm#

5.0t Kcpm#

0.499 Kcpm#

0.499Kqim#

Readings wrtll

  • Indicate ranges v.tiere As-Found readings are >20% of Target valUe Readings with ** Indicate As-ten readings are > 1 oo,. orTarget value.

Readings with # mdicate ranges were calibrated using a pulser Serial Number 25035113 Serial Number 190949 I

ResUlts I

Pass Source ID Pulser 98756 Pulser 98756 Pulser 987 56 Pulser 98756 Probe Isotope Efficiency NIST Source ID Geometry Comment 43-37 190949 Tc-99 43-37 190949 Cs-I37(Beta) 43-37 190949 Tc-99 43-37 190949 CS-I37(Beta)

Phvslcal Checks outer Phys cal Check: Pass Tap Test Pass Audio Ft.icllOn Check Pass Galibration Date Set. Pass 0.0585 CID (4 Pl) 0 1703 CID (4 Pl) 0.0276 CID (4 Pl) 0.0387 CID (4 Pi) 127356 Tc-99 127357 Cs-I37(Beta) 127356 Tc-99 127357 Cs-137(Beta)

Electronics Checks HI hV e

Flat Surface Flat Surface Flat Surface Flat surface As Found 900 Volts 3/4" Above Flat Surface 3/4" Above Flat Surface 3/4" NJove Grate 3/4" NJove Grate As Left 1800 Volts Comments: Galrbrated with Ludlum 43-37 SIN 190949 USlllg 20' C to C cable for wan aoo overhead set up.

Customer Equ,pment ID:

Calibrated By NICOie WedIg oc Review By Matthew Hunter Atmospllerlt Cood ;.ons

  • Temperature* 70 0 'F, Humidrty* 24.0 '4. Baromemc Pres.swe:30 12 rnlhg.

Date: Jan 31, 2024 Expires: Jan 3 t. 2025 ac Date. Jan 31 2024 In tolerance conditions,re based on tes1 results f3'Iing with n specified lim,:s with no re<lutlioo by tile un<:ertaimy of the measurement ThJS c:ilihratioo was performed by RSCS using the folowng NIST Traceable soorces P\\llser 98756 - (C:1I Due* oa 31 2024) il'Oll<ed on c:ilbra.ion: N COie 1',eoig The repcned expanoed uncertain.'Y or measureme111 Is s:a:.ed as the sltlnd:110 uncerutnr/ or measurement 100ltlplied by me coveraoe factor k such at the coverage pn,b3bl ity correspoods to 31)pro,lm:ite'V 95'11,.

Unless o;her.,.se stated cal hratJOns performed In conformance to tne fo;to,.;ng docun nts AI\\SI N323AB-2013; RSCS New Hampshire R3dioactJVe Ma:ertal License Number 381R RSCS ca bra servlc..,re performed In accordance wllh the RSCS R3dl:rlon Pmtectioo Program M,nual :ind Standard Opera~ng Procedures Calibratioo L3l>or.ltory Is ooerated *n accordance.,,,th ANSI/NCSL Z.540-1-1994.

RSCS, Inc. has been assessed by ANA8 ano meets the req.irreme s of ISO/l~C 17025:2017 while demonstrating techn*cal competence n the field of calibr.ltion. Refer to tho StOl)e of Accredrtatioo AC-2079 for lrtorm>tioo oo lhe ~}Pe' of cal.bra1Jons to which

  • s a<:credrtation apples.

Th*s c:illbr.ltion ~cate sh:l not be reproduced except n flJII withOut the e,press written consent of RS~ Inc.

Racuten S:I~& Ccnwal s.v.s In,:

~ltdgtRoa,;~~Olc.-'

200) ~

l~:31474-CT:l Survey Unit STR-101-02 Containment Vessel (CV) - 1st Level (Tanktop), Port Side 11 Page 23 of31

SAVANNAH Technical Staff Survey Unit Release Record C.ilibratlon Certlfic:;ite

  • ID Numbar: 25035132000
  • 20240305
  • 1 RSCS Customer: Matthew G Hunter Rad at10n Safety & Control services. Inc 93 Ledge Road Seabrook NH 03874 Instrument Ludlum Model 3002 Probe Modtl Ludlum 43-93 Precision Check Serl.ii Number 25035132 Serl.ii Number 421425 Testl Test2 Test3 Mean Results 5.00 kcpm 4.99 kcpm 4.99 kcpm 4.99 kcpm Accuracy Check Ran e Ta t Value As Found As Lett AUTO 500 Kcpm fl 499 Kcpm #

AUTO 50 Kcpm If 50 Kcpm #

AUTO 5 Kcpm #

5 Kcpm #

499 Kq:>m#

50 Kcpm#

5Kcpm#

AUTO 0.5 Kcpm #

0 498 Kcpm #

0.498Kcpm#

Readings with 'Indicate ranges \\\\tiere As-Found readings are >20% ol Target value.

Readings with ** Indlca1e As-left read,ngs are > 10% of Target value.

Readings with # U1dIcate ranges were calibrated usJng a pulser Probe Isotope 43-93 421425 Tc-99 43-93 421425 Cs-137(Beta) 43-93 421425 Cs-137(Beta) 43-93 421425 Tc-99 43-93 421425 Cs-I 37(Beta) 43-93 421425 Tc-99 43-93 421425 Cs-137(Beta) 43-93 421425 Tc-99 Physic.ii Chicks Light Check or SCUllllallon Probes Pass Outer Physical Cheek Pass Tap Test Pass Audio Function Cheek Pass Cord cheek Pass Calibrntion Date Set. Pass Efflclancy 0 0243 CID (4 Pl) 0 0505 CID (4 Pl) 0.0398 CID (4 Pl) 0.0177 CID (4 Pl) 0.1620 CID (4 Pl) 0.1108 CID (4 Pl) 0.1193 CID (4 Pl) 0.082 I CID (4 Pl)

Comments caI,brated with 20' c to c cable Customer Equ*pment ID:

NIST Source ID 127356 Tc-99 127357 Cs-137(Beta) 127357 Cs-I37(Beta) 127356 Tc-99 127357 Cs-l37(Beta) 27356 Tc-99 127357 Cs-l37(Beta) 127356 Tc-99 Eltctronlcs Chicks Hi Geomttry Flat SUrface Flat surface Flat Surface Flat surface Fial surface Flat surface Flat surface Flat surface As Found 678 Volts P.iss Source ID Pulser 98756 Pulser 98756 Pulser 98756 Pulser 98756 comment On Grate On Grate 314" Above Grate 314" Above Grate On Contact On Contact 314" Above Source 314" />Dove Source As Lift 780 Volts Calibrated By Nicole Wedig OC Review By Matthe\\*

Hunter Date: Mar 05. 2024 EJCpires: l\\'1ar 05, 2025 QC Date* Mar 05, 2024 Almosphenc Cond uOnS -

emper3rure 71 1 'F, Humidity 36.0 "

  • B:lrome Pre

.30.29111/hO In tolerance conchuons.1re based on tes re t.l

  • wrth,n specified Rm.ts Y11th no redut by the unce11311\\ty of the me3su emenl Unless o*

rv,,se Slated S C3I brallon W3S pertonned by RSCS 31 93 ledge Rd Se3br00k. NH Ill' bog the follow ng NIST Tf3C83ble sources Pulser 98756 - (C3I Due Oct 31 2024)

Worl<ed on cal bra~on: N ccle Wedlg The reported exp:inded ur,cel131nty of me3sureme is su:ed 3S the stancbrd uncen:unty or me:isurement multiplied by the coveraoe factor k such U\\31 the coveraoe prob3bl,ty corresponds to :ippro m3te 95'W.

Lnless 01.rw,se stated C3I tJOllS perfOffl'ed tn COl'f0nl13nce to to

... mg oocumertts. MSI N323AB-2013: RSCS New 3mpsh1re R30103CLV8 M:l:en license Number 381 R RSCS C3 bra on serv,ces an, performed In 3tcol'd:ince with the RSCS R3dia1on ProtectJon Program M3nU3I and Stand3ro Operatmo Procedures Racutcn s.-,.' Conl-ol ~- Inc

~uagtRo.>: s.boot.~OlE."."4 Survey Unit STR-101-02 Containment Vessel (CV) - 1st Level (Tanktop), Port Side 11 Page 24 of3 I

SAVANNA H Technical Staff Survey Unit Release Record calibration Certificate

  • ID Number: 25035134000
  • 20240606

... cc Customer: Scott Ginter Radiation Safety & COntrol Services, Inc.

93 Ledge Road Seabrook NH 03874 Testl Test2 49.90 kcpm 49.90 kcpm Instrument Ludum Medel 3002 Probe Model LUdlum 43-93 Precision Check Test3 Mean 49.90 kcpm 49.90 kcpm Accuracy Check Ran e T

et Value As Found As Lett AUTO 500 Kcpm #

500 Kcpm #

AUTO 50 Kcpm #

49 9 Kcpm #

AUTO 5 Kcpm #

5 Kcpm #

Serial Number 25035134 Serial Number 421368 Results Pass Source ID Pulser 66151 Pulser 66151 Pulser 66151 Pulser 66151 AUTO 0.5 Kcpm #

0.5 Kcpm #

500Kcpm#

499Kcpm#

5Kcpm#

0.5Kcpm#

-~

Readings with

  • Indicate ranges Where As-Found readings are :.20~. or Target vah.Je.

Readings with - indicate As-left reael,ngs are > 10% or Target value.

Readings with # indicate ranges were calibrated using a pulser Probe Isotope 43-93 421368 Cs-137(Beta) 43-93 421368 Tc-99 43-93 42 I 368 Cs-137(Beta) 43-93 421368 Tc-99 43-93 421368 cs-137(8eta) 43-93 421368 Tc-99 43-93 42 1368 Cs-137(Bet.i) 43-93 421368 Tc-99 Physical Checks Light Chee of Scintilabon Probes Pass OUter Physical Check: Pass Tap Test Pass Audio Function Check Pass Cord check Pass Efficiency NIST Source ID 0.0158 CID (4 Pl) 127357 Cs-t 37(Beta) 0.0162 CID (4 Pl) 63963 (Beta) Tc-99 0.0 I 60 CID (4 Pl) 127357 Cs-137(Beta) 0 0055 CID (4 Pl) 127356 Tc-99 0.1755 CID (4 Pl) 127357 Cs-137(Beta) 0.0975 CID (4 Pl) 127356 Tc-99 0 1238 CID (4 Pl) 127357 Cs-137(Beta) 0.0658 CID (4 Pl) 127356 Tc-99 Electronics Checks Hi hV e

Comments Elfaencles performed using 1 5" fiberglass grate as requested.

Customer Equ,pment ID:

Calibrated By N COie Wedig OC Review By l'v\\atthei Hunter Atmosp ric Cond tiOOS - Temperature 71 o 'F. Humkf11y 52.0 %, Barome:nc Pres,ure:29.62 mo.

Geometry Comment Flat Surface On Grate Flat Surface On Grate Flat Surface 3/4" Above G rate Flat Surface 314" Above Gra le Flat Surface on contact Flat Surface On Contact Flat Surface 314" AJJove Sou rce Flat Surface 314* Above So urce As Found As Left 700Volts 700 Volts Date: Jun 06, 2024 Expires: Jun 06. 2025 oc Date Jun 06. 2024 In tderance condillons are based on Iest resalts fa'!Jno wtlh n specified llm">s wi1h no reducfion by the uncertainty of the measurement The resuns contal d herein relate only to

.,em caLbrated Unless OlheM se Stated IS C3I bration W3S performed by RSCS 31 93 Ledge Rd. Seabrook NH eing me follow no NIST Traceable sources Pulser 66151 - (c:JI Dt,e: Apr 05 2025)

Worl<ed 011 cal braLOO: Chns Pirie\\ Nicole Wed,g The reported expanded uncertainty of measurement Is s:a:ed as the standard unc,orta nty of measurement n>Jltlplied by the c0'1eraoe facto, k such tnat the coverage probabl Ity corresponds o approXJm31e'Y 95%.

Unless o eiwise stateo C31m ons perf0fll1ed., contooronce tot e foilowlfl!I documents: MSI N323AB-2013; RSCS New H3mpsrure Raato3CIJ\\'e M3:erial License JI.umber 381 R RSCS ca'Ibration seiv,ces are performed in accordance,.ith tile RSCS Rad1anon Protection Program M3nU31 and S131ldard Operabno Proced res Cal bratlon Laboratory Is operated 1n acco dance with ANSI/NCSL 2540-1-1994.

ro!!aonSntyleor.ol~ ff:

12

'3~Ro>c..,._

0Je7*

,aoo 5:~

te:11,"."4-t.7~

t Survey Unit STR-101-02 Page 25 of3 I Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record Meter ID 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035132 25035134 25035134 25035134 25035134 25035134 - Static Data Count Rate Total Weighted Eff Measurement ID (cpm)

(c/d)

STR-101-02-01 148 0.0858 STR-101-02-02 136 0.0858 STR-101-02-03 217 0.0858 STR-101-02-04 93 0.0858 STR-101-02-05 834 0.0858 STR-101-02-06 620 0.0858 STR-101-02-07 138 0.0858 STR-101-02-08 117 0.0858 STR-101-02-09 107 0.0858 STR-101-02-10 290 0.0858 STR-101-02-11 181 0.0858 STR-101-02-12 118 0.0858 STR-101-02-13 183 0.0858 STR-101-02-14 109 0.0858 STR-101-02-15 120 0.0858 STR-101-02-16-J 2100 0.0858 STR-101-02-17-J 197 0.0858 STR-101-02-18-J 211 0.0159 STR-101-02-19-J 199 0.0159 STR-101-02-20-J 162 0.0159 STR-101-02-21-J 99 0.0159 STR-101-02-07-D 71 0.0920 Note: Meter ID 25035132 and 25035134 are connected to a Ludlum model 43-93 detector with an area of 100 cm2.

t Survey Unit STR-101-02 Page 26 of3 l Containment Vessel (CV) - l st Level (Tanktop ), Port Side

SAVANNAH Technical Staff Survey Unit Release Record Date Scan ID 7/15/24 SA-01 7/16/24 SA-01 7/16/24 SA-02-J - Scan Data Min/Max Range Meter ID C m 25035113 200/2000 25035132 136/4200 25035134 72/220

)' - - --

t Total Average Weighted Cm Eff c/d) 1100 0.0802 2168 0.0632 146 0.0142 Note: Meter ID 25035113 is connected to a Ludlum model 43-37 detector with an area of 584 cm2. Meter ID 25035132 and 25035134 are connected to a Ludlum model 43-93 detector with an area of I 00 cm2.

Survey Unit STR-101-02 Page 27 of31 Containment Vessel (CV) - I st Level (Tanktop ), Port Side

SAVANNA H Technical Staff Survey Unit Release Record - Quality Control Assessment Measurement Initial measurement Absolute Value of the difference Condition d m/100 cm2 Avera e < 52,300 Survey Unit STR-101-02 Absolute value of the difference 837.49 Containment Vessel (CV) - I st Level (Tanktop), Port Side Value d m/100 cm2 1609.22 771.73 1190.475 837.49 Control Limit d m/100 cm2 11087.6 Result Pass Page 28 of31

SAVANNAH Technical Staff Survey Unit Release Record - Sign Test Measurement Result ID (dpm/100 cm2)

STR-101-02-01 1725.83 STR-101-02-02 1585.89 STR-101-02-03 2530.44 STR-101-02-04 1084.47 STR-101-02-05 9725.27 STR-101-02-06 7229.81 STR-101-02-07 1609.22 STR-101-02-08 1364.34 STR-101-02-09 1247.73 STR-101-02-10 3381.69 STR-101-02-11 2110.64 STR-101-02-12 1376.00 STR-101-02-13 2133.96 STR-101-02-14 1271.05 STR-101-02-15 1399.32 STR-101-02-16-J 24488.08 STR-101-02-17-J 2297.22 STR-101-02-18-J 13270.44 STR-101-02-19-J 12515.72 STR-101-02-20-J 10188.68 STR-101-02-21-J 6226.42 Parameter Survey Unit STR-101-02 Number of Measurements Number of S+

Critical Value Meets I Doesn't Meet Acee tance Criteria Containment Vessel (CV) - !st Level (Tanktop), Port Side DCGLw - Result (dpm/100 cm2) 67974.17 68114.11 67169.56 68615.53 59974.73 62470.19 68090.78 68335.66 68452.27 66318.31 67589.36 68324.00 67566.04 68428.95 68300.68 45211.92 67402.78 56429.56 57184.28 59511.32 63473.58 Result 21 21 14 Meets j

Sign

+I

+l

+1

+1

+)

+I

+l

+1

+l

+l

+1

+l

+l

+1

+1

+]

+]

+]

+l

+1

+]

Page 29 of31

SAVANNAH Technical Staff Survey Unit Release Record - Graphical Presentations Quantile Plot of Gross Activity Concentration 26000 24500

,-... 23000 N

~ 21500 u

o 20000 0

18500

[

17000

~ 15500 C: o,,moo

_ti 12500 5 I 1000

(.)

§ 9500 U

8000 f 6500

  • B 5000

<I'.'.

3500 2000 * *

  • 500 0%

10%

Survey Unit STR-101-02 20%

30%

40%

50%

60%

Containment Vessel (CV) - I st Level (Tanktop ), Port Side 70%

80%

1 90%

100%

Page 30 of31

SAVANNAH Technical Staff Survey Unit Release Record Histogram Survey Unit Number: STR-101-02 Containment Vessel (CV) - 1st Level (Tanktop)

Survey Unit Name: Port Side 16 14 12 G' 10 C

Q) 8

i 0-Q) c.i..

6 4

2 0

4010 Survey Unit STR-101-02 7010 I I

  • 100 10 130 10 160 10 19010 Upper End Value (dpm/ 100 cm2)

Containment Vessel (CV) - 1st Level (Tanktop), Port Side 220 10

  • 250 10 Page 31 of3 I
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