ML25328A172

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Us Dept of Transportation - Nuclear Ship Savannah, Survey Unit Release Record Survey Unit STR-105-03 Reactor Compartment (Rc) - Lower Level, Drain Wells
ML25328A172
Person / Time
Site: NS Savannah
Issue date: 11/20/2025
From: Hollenbeck P
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-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells Approved: Z Senior Technical Advisor Prepared by:

Nuclear Ship Support Services, LLC

SAVANNAH 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 COMPLIANCE MANAGER REVIEW/ DATE:

SAFETY REVIEW COMMITTEE SUBMITTED/APPROVED Survey Unit STR-105-03 Pete Hollenbeck Pete Hollenbeck, CHP D. Roberson Douglas Roberson Digitally signed by Pete Hollenbeck Date: 2025.04.28 13:33:21 -04'00' Date Digitally signed by D. Roberson Date* 2025 04 28 l 2*5Z*l 2 -05'00' Date Soeuth Caleb Soeun DigitallyslgnedbySoeuthCalebSoeun Date: 2025.04.29 07:53:13 -04'00' Soeuth C. Soeun James Reese, CHP, RRPT James Reese Date Digitally signed by James Reese, CHP, RRPT Date: 2025.04.30 07:49:07

-07'00' Date Da n

  • 1 e I R M
  • 1 ha 1
  • 1 k Digitally signed by Daniel R. Mihalik Date: 2025.04.30 15:23:00 -04'00' Daniel Mihalik John Osborne LCM John Osborne 5/12/2025 Submitted Date Digitally signed by: John Osborne LCM DN: CN = John Osborne LCM email

= jmosbome@nsss.llc C = AD Date: 2025.05.20 08:32:20 -05'00' Date 5/20/2025 Approved Page 2 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record TABLE OF CONTENTS

1.

EXECUTIVE S"UMM.ARY.................................................................................................... 6

2.

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

3.

CLASSIFICATION BASIS................................................................................................... 6

4.

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

SURVEY DESIGN............................................................................................................... 10

6.

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

7.

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

8.

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

9.

INVESTIGATIONS AND RESULTS................................................................................ 16

10. REMEDIATION AND RES UL TS...................................................................................... 16
11. CHANGES FROM THE FINAL STATUS SURVEY PACKAGE................................. 17
12. DATA QUALITY ASSESSMENT (DQA)......................................................................... 17
13. ANOMALIES........................................................................................................................ 17
14. CONCLUSIONS................................................................................................................... 17
15. REFERENCES..................................................................................................................... 17
16. ATTACHMENTS................................................................................................................. 18 Survey Unit STR-105-03 Page 3 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record LIST OF TABLES Table 4 Radionuclide Fractions and Normalized Fractions............................................... 8 Table 4 15 mrem/y DCGLs for ROC and Ni-63.................................................................. 8 Table 4 Re-normalized Co-60 and Cs-137 Fractions.......................................................... 9 Table 4 Operational DCGLs................................................................................................ 10 Table 5 STR-105-03 Systematic Measurement Designations........................................... 11 Table 5 Scanning Coverage................................................................................................. 12 Table 5 Investigation Levels................................................................................................ 13 Table 7 Summary of Systematic, Judgmental, and QC Static Measurements................ 14 Table 7 Basic Statistical Properties of Static Measurement Population.......................... 15 Table 7 Scan Measurement Summary................................................................................ 16 Survey Unit STR-105-03 Page4 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record LIST OF ACRONYMS AND ABBREVIATIONS ALARA As Low As Reasonably Achievable DQA Data Quality Assessment DQO Data Quality Objective DCGL Derived Concentration Guideline Level FSS Final Status Survey HSA Historical Site Assessment IC Insignificant Dose Contributors LBGR Lower Bound of the Gray Region LTP License Termination Plan MARAD Maritime Administration MARSSIM Multi-Agency Radiation Survey and Site Investigation Manual MDC Minimum Detectable Concentration MDCR Minimal Detectable Count Rate NSS Nuclear Ship Savannah QC Quality Control RASS Remedial Action Support Survey ROC Radionuclides of Concern SOF Sum-of-Fraction TEDE Total Effective Dose Equivalent UBGR Upper Bound of the Gray Region USNRC United States Nuclear Regulatory Commission Survey Unit STR-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells Page 5 of29

SAVANNAH Technical Staff Survey Unit Release Record

1.

EXECUTIVE

SUMMARY

This Survey Unit Release Record for survey unit STR-105-03, Reactor Compartment (RC)

Lower Level, Drain Wells, has been generated in accordance with Maritime Administration (MARAD) procedure STS-005-035, Preparation of Survey Unit Release Records and FSS Final Reports [ 1] and satisfies the requirements of Section 5.10 of the Nuclear Ship SAVANNAH (NSS) License Termination Plan, STS-004-003 [2].

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 [3], the NSS License Termination Plan (LTP), and with guidance from NUREG-1575, Revision 1, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) [4].

This survey unit has a MARS SIM 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 II (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. In addition, two (2) judgmental static beta measurements were acquired.

Surface scanning was performed on 100% of the accessible total surface area in the survey unit. The data assessment results for survey unit STR-105-03 show that the maximum gross activity concentration among systematic and judgmental measurements is equal to 3,932.53 dpm/100 cm2, which is 7.52% of the operational Derived Concentration Guideline Level (DCGLw) value of 52,300 dpm/100 cm2. Therefore, the null hypothesis of the Sign Test is rejected, and survey unit STR-105-03 is acceptable for unrestricted release. The mean gross activity concentration among the systematic and judgmental measurements is equal to 1,276.94 dpm/100 cm2, which is 1.83% of the 15 mrem/y gross activity DCGLw of69,700 dpm/100 cm2. The mean gross activity concentration is equal to 0.27 mrem/y for the survey unit.

2.

SURVEY UNIT DESCRIPTION STR-105-03 is an impacted Class 1 survey unit. There are two Drain Wells in the Reactor Compartment Lower Level, the aft and forward. Based upon Computer Aided Design drawings, the Drain Wells deck surface area is approximately 2.44 square meters (2.44 m2). The total surface area including the bulkheads and overhead of the Drain Wells is 10.5 m2. Refer to Attachment 1 of this report for figures and maps depicting survey unit STR-105-03.

3.

CLASSIFICATION BASIS Based on the NSS Historical Site Assessment [HSA] [5], survey unit STR-105-03, which is encompassed in survey unit 109Al in the HSA, was identified as a Class 1 structure survey unit. The Reactor Compartment contains support systems for the reactor plant.

Survey Unit STR-105-03 Page 6 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Primary coolant leaks were experienced from time to time, as was typical of nuclear power plants of the era. Typically, spills were cleaned up shortly after they occurred, apart from hard-to-reach areas, i.e., underneath the vessels, around pipes and hangers. Based upon a review of the historical information, the results of the characterization survey data, the 2024 Remedial Action Support Survey (RASS) of the Reactor Compartment Lower Level, STR-105-RASS-01-Rev 0, and the completion of a final Survey Unit Classification Worksheet, the correct final classification of survey unit STR-105-03 met the requirements of 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 LTP in accordance with MARSSIM. The appropriate design for a given survey was developed using the DQO process as outlined in Appendix D ofMARSSIM.

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-105-03 did not exceed the release criteria specified in the LTP and that the potential dose from residual radioactivity is As Low As Reasonably Achievable (ALARA).

MARAD Contractor Report CR-139, Calculations to Support NSS Su,face Contamination DCGLs [ 6] 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 [7]. In all analyses, Cs-137 and Co-60 contribute nearly 100% 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-137 and Co-60surrogate.

Survey Unit STR-105-03 Page 7 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record 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 4-1-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+o0 9.00E-01 9.00E-01 Sr-90 9.22E-06 l.54E-06 Tc-99 l.27E-04 2.llE-05 Ag-108m 8.30E-04 1.38E-04 Cs-137 4.57E-01 7.61E-02 7.61E-02 H-3 l.93E-03 3.21E-04 Fe-55 8.l0E-03 1.35E-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 presents the 15 mrem/y DCGLw for Co-60, Ni-63 and Cs-137 from Chapter 6 of the L TP.

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-137 l.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:

Survey Unit STR-105-03 Page 8 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record DCGL DCGLETD X DCGLnrD surrogate =

(f HTD:EToXDCGLEm)+DCGLnrD Where:

DCGLETD = the DCGL for the easy-to-detect radionuclide DCGLHTD the DCGL for the hard-to-detect radionuclide Equation 1 FHTD: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.

2.53E+08 2

DCGLco-60 surrogate - 2.37E + 04 X (

)

- 2.36E+04 dpm/100 cm 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:

fn n

DCGLn 1

Gross Activity DCGLw = ti 12 tn DCGL1 + DCGLz +***vcGLn

= fraction of the total activity contributed by radionuclide n

= the number of radionuclides

= DCGL for the Radionuclide of Concern (ROC)

Equation 2 Of the three radionuclides, only Co-60 and Cs-13 7 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 presents the re-normalized fractions for each radionuclide.

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 l.63E-02 l.76E-01 Ni-63 9.00E-01 Sr-90 l.54E-06 Tc-99 2.1 lE-05 Ag-108m l.38E-04 Cs-137 7.61E-02 7.61E-02 8.24E-01 Survey Unit STR-105-03 Page 9 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Nuclide H-3 Fe-55 Am-241 Pu-239/240 Totals Normalized sum of fractions 3.21E-04 l.35E-03 9.66E-08 8.0lE-08 l.00E+00 Only Co-60 Re-and Cs-137 normalized Fractions Fractions 9.24E-02 l.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 l.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. MARS SIM states that a Minimum Detectable Concentration (MDC) below 10%

of the DCGL is preferable and up to 50% is acceptable. Because the background is low on the NSS, the MDC 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 LTP 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 Survey Unit STR-105-03 Page 10 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record The Number of Measurements For Final Status Surveys. [8] The relative shift (f:Jcr) 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 (CJ), which is the standard deviation of the data set used for survey design.

The optimal value for f:Jcr should range between one (1) and three (3). The largest value the Ncr can have is three (3). If the ~/cr exceeds three (3), then the value of two (2) will be used for f:Jcr.

A RASS survey of the RC Lower Level was performed between 04/08/24 and 05/06/2024.

A total of thirty-five (35) static measurements and 35 smears were collected. Only 4 smears had positive alpha activity with the maximum at 43.27 dpm/100 cm2. The maximum beta activity was 305.74 dpm/100 cm2. The average total surface activity concentration and standard deviation of the measurements were 1,479.06 and 1,379.71 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-105-03 is based upon the RASS survey results and was calculated as follows:

52,300-26,150 Relative Shift= ------ = 18.95 1,379.71 Because the calculated relative shift was greater than three (3), the value of two (2) was used as the adjusted f:Jcr. Both the Type I error, or a value, and the Type II error, or~ value, was set at 0.05. The sample size from Table 5.5 of MARSSIM that equates to the Type I and Type II error of 0.05 for use with the Sign Test is an N value of fifteen (15). Fifteen (15) total systematic measurements were used in the survey design for survey unit STR-105-03.

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 1). Table 5-1 lists the systematic measurements to be collected for FSS of survey unit STR-105-03.

Table 5 STR-105-03 Systematic Measurement Designations Label LX(m)

LY(m)

Surface Area STR-105-03-01 0.45 1.23 Deck Aft Drain Well STR-105-03-02 0.62 0.07 Overhead Aft Drain Well STR-105-03-03 0.14 0.91 Overhead Aft Drain Well STR-105-03-04 0.48 0.38 Bulkhead2 Aft Drain Well STR-105-03-05 0.71 0.38 Bulkhead 3 Aft Drain Well Survey Unit STR-105-03 Page 11 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Label STR-105-03-06 STR-105-03-07 STR-105-03-08 STR-105-03-09 STR-105-03-10 STR-105-03-11 STR-105-03-12 STR-105-03-13 STR-105-03-14 STR-105-03-15 LX{m) 0.06 0.29 1.26 0.25 1.22 0.80 0.15 1.12 0.57 0.73 LY{m) 0.38 0.38 0.38 0.77 0.77 0.66 0.54 0.54 0.54 0.54 Surface Area Bulkhead4 Aft Drain Well Bulkhead 1 Aft Drain Well Bulkhead 1 Aft Drain Well Deck Fwd Drain Well Deck Fwd Drain Well Overhead Fwd Drain Well Bulkhead4 Fwd Drain Well Bulkhead4 Fwd Drain Well Bulkhead 1 Fwd Drain Well Bulkhead2 Fwd Drain Well 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-105-03-06 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 judgmental measurements to augment the systematic measurements. The locations of these two measurements were to be determined by the technicians and/or the field supervisor. Those two judgmental measurements are identified as STR-105-03-16-J and STR-105-03-17-J. Those locations would be documented on the field forms.

For this Class 1 structure survey unit, the "Scanning Coverage" are those levels specified in LTP Chapter 5, Table 5-3, and are reproduced below in Table 5-2.

Table 5 Scanning Coverage Classification Required Scanning Coverage Fraction Class 1 100%

For survey unit STR-105-03, twelve scan areas were established, six areas in each Drain Well. Each surface was designated as a scan area. 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-105-03.

For this Class 1 structure survey unit, the "Investigation Levels" for direct and scanning measurement results are those levels specified in LTP Chapter 5, Table 5-2, and are reproduced below in Table 5-3.

Survey Unit STR-105-03 Page 12 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Survey Unit Classification Class 1 Table 5 Investigation Levels Fixed Measurements Scan Measurements

> Operational DCGLw > Operational DCGLw and an outlier*

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 of 2,500 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-I05-03, compliance with the unrestricted release 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 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. [9] 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-I 05-03-00-00, which included DQOs, survey design, detailed FSS instructions, survey maps and survey forms. FSS field activities were projected to take two (2) 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 one day to complete and were performed on Dec 3, 2024.

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.

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 I-minute static measurement was acquired at each location with the detector in contact with the surface.

All of the twelve (12) planned scan areas, SA-01 through SA-I2, were scanned, resulting in 100% of the total surface area being scanned. The total scan area meets the scan coverage Survey Unit STR-105-03 Page 13 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record 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.

The implementation of survey specific QC measures included the collection of one replicate static measurement. The random location of the replicate measurement was STR-105-03-06 and identified as STR-105-03-06-D. That measurement was collected with a different instrument but the same make and model used for all the other measurements.

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 [10]. For example, 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 I-minute count was 100 cpm. Using the contact detector weighted efficiency of 0.1023 c/d for a painted surface and using LTP Equation 5-6, which was derived from NUREG-1507, in which the count time and background count times are equal, results in an MDC for a I-minute static measurement equal to 483.8 dpm/100 cm2. That value is less than 1% of both the operational DCGLw and the gross activity DCGLw. Table 7-1 presents the activity concentration for all static measurements.

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

STR-105-03-01 1017.03 STR-105-03-02 576.32 STR-105-03-03 542.42 STR-105-03-04 779.73 STR-105-03-05 711.92 STR-105-03-06 610.22 STR-105-03-07 689.32 STR-105-03-08 723.22 STR-105-03-09 3096.30 Survey Unit STR-105-03 Page 14 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Measurement ID STR-105-03-10 STR-105-03-11 STR-105-03-12 STR-105-03-13 STR-105-03-14 STR-105-03-15 STR-105-03-16-J STR-105-03-17-J STR-105-03-06-D Activity Concentration (dpm/100 cm2) 3333.61 1457.75 926.63 508.52 3932.53 689.32 1265.64 847.53 674.41 The raw static data with detector efficiencies are presented in Attachment 3.

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

Table 7 Basic Statistical Properties of Static Measurement Population Parameter Value Units Minimum Measurement 508.52 dpm/100 cm2 Maximum Measurement 3932.53 dpm/100 cm2 Mean 1276.94 dpm/100 cm2 Median 779.73 dpm/100 cm2 Standard Deviation 1079.02 dpm/100 cm2 Coefficient of Variation 0.85 unitless Residual activity dose rate 0.27 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 dose attributed to the survey unit. For survey unit STR-105-03, the calculated dose from residual activity is 0.27 mrem/yr.

Calculation of the scan MDC for the Ludlum 43-93 detector used the rounded-up count rate of 75 cpm, the detector weighted efficiency of 0.0642 c/d for a painted surface at a distance of 0.75 inches and using LTP Equation 5-8, which was derived from NUREG-1507. The elevated area was assumed to be a 100 cm2 circular source. The detector width is 3.6 inches, and 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 1,835.2 dpm/100 cm2. That value is 3.5% of the operational DCGLw and 2.6% of the gross activity DCGLw.

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

Survey Unit STR-105-03 Page 15 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Table 7 Scan Measurement Summary Low to High Range Average Scan ID

( dpm/100 cm2)

( dpm/100 cm2)

SA-01 498.09 - 2288.10 1393.10 SA-02 435.83 - 1400.88 918.36 SA-03 295.74 - 1400.88 848.31 SA-04 295.74 - 1649.92 972.83 SA-05 342.44 - 980.61 661.53 SA-06 404.70 - 840.53 622.62 SA-07 1914.53 - 4404.98 3159.76 SA-08 544.79 - 3611.15 2077.97 SA-09 451.39 - 1307.49 879.44 SA-10 1089.57 - 1587.66 1338.62 SA-11 700.44 - 2506.02 1603.23 SA-12 622.61 - 1821.14 1221.88 The raw scan data with detector efficiencies are presented in Attachment 3.

8.

QUALITY CONTROL The implementation of survey specific QC measures included the collection of one replicate static measurement (STR-105-03-06-D) for analysis. The acceptance criteria for replicate static measurements is defined by NUREG-1576, MARLAP volume 1, Appendix C, Section C.4.2.2 Duplicate Analyses [11]. 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 value for µMR.is equal to the shift divided by 10.

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 quality control measurement show agreement between the original and duplicate measurements. See Attachment 4 for the results.

9.

INVESTIGATIONS AND RESULTS No investigation levels were triggered, and no investigations were performed as the result of the analysis of the collected data.

10.

REMEDIATION AND RESULTS No radiological remedial action was performed in this survey unit as a result of the FSS.

Survey Unit STR-105-03 Page 16 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record

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, Preparation of Final Status Survey Packages [3].

12.

DATA QUALITY ASSESSMENT (DQA)

The DQO sample design and data were reviewed in accordance with MARAD procedure STS-005-033, Final Status Survey Data Assessment and Investigation [12] 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 of calculating 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.

Although MARSSlM states that the Sign Test need not be performed in the instance that no measurements exceed the DCGL, 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 release 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 Survey unit STR-105-03 has met the DQOs of the FSS package. The survey unit is properly classified as Class 1.

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-105-03 is 0.27 mrem/yr TEDE, based on the mean activity of measurements used for non-parametric statistical sampling.

Survey unit STR-105-03 is acceptable for unrestricted release.

15.

REFERENCES

[1]

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

[2]

"STS-004-003, N.S. Savannah License Termination Plan".

Survey Unit STR-105-03 Page 17 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record

[3]

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

[4]

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

[5]

"CR-003, STS-109, Historical Site Assessment, 2008".

[6]

"CR-139, TSD 21-089, Calculations to Support NSS Surface Contamination DCGLs, Rev 01, September 2022".

[7]

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

[8]

"STS-005-031, Calculation of The Number of Measurements For Final Status Surveys".

[9]

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

[10] "CR-164, TSD 23-126, "Calculation ofWeighted Efficiencies and MDCs of Ludlum Detectors for Final Status Surveys on the NS Savannah", Rev 01 ".

[11] "NUREG-1576, Multi-Agency Radiological Laboratory Analytical Protocols Manual, MARLAP, July 2004".

[12] "STS-005-033, Final Status Survey Data Assessment and Investigation".

16.

ATTACHMENTS - Figures and Maps - Calibration Records - Static and Scan Data - Quality Control Assessment - Sign Test - Graphical Presentations Survey Unit STR-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells Page 18 of29

SAVANNAII Technical Staff Survey Unit Release Record Survey Unit STR-105-03 - Figures and Maps Location of the Reactor Compartment Lower-Level Drain Wells (5' Elevation)

D l BOW h Reactor Compartment (RC)- Lower Level, Drain Wells Page 19 of29

SAVANNAtt Technical Staff Survey Unit Release Record Reactor Compartment Lower-Level Drain Wells Systematic and Judgmental Static Locations D

  1. TI>- 105-03-C,
  1. P-1 !~3- ~J
rq. 0$-Cl ow.....

.S

  • 0~ C3-lr-D

,-P-1~---03-1 l eu,-..aa, n:o.*o~- 1 Diel s~- 05 *.J "TR-IJ!>-03-11 VSP origin point in ship coordinates: Drain Well Deck Frame 123 VSP origin point in ship coordinates: Drain Well Deck Frame 106 5' 0" Starboard of Centerline 3' 0" Above Baseline 7' 7" Starboard of Centerline 3' 0" Above Baseline LEGEND*

NOTES*

!l.r.xeO!gffl Survey Unit STR-105-03 Reactor Compartment (RC)- Lower Level, Drain Wells

  • LE LOCATIONS CREATED ~~

SUAL SAA LE PlA NUMBERCFSAMPLES. 15 PLACEl,'ENT II. ETrlOO: SYSTE C

START LOC* RAt DO BOW h Page 20of29

SA VANNA II Technical Staff Survey Unit Release Record Reactor Compartment Lower-Level Drain Wells Scan Areas D

D

>o::t JG

°""

J

':Ml

!lA-06 s;..oe S.A-C7

~10

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. I Survey Unit STR-105-03 Reactor Compartment (RC)- Lower Level, Drain Wells 1 - ** - - rst

°'-"'

  • *12 BOW h Page 21 of29

S1vANNAJJ Technical Staff Survey Unit Release Record - Calibration Records

~on C. ficate. ID umber 25011651000 20240305 - f Cu t S brook NH 03874 Ludlum 43-93 Precision Check TH :2 T~~*~

5.01 ep:.:.-n;...... _ _.__ __

.:;5.:.:.00.:....:.:.kc::.,p,n

--L----'c...:...:"--'

Accurac Check A!.Found 500 Kcp,-, I 49 ll Kcpm #

AUTO AUTO AUTO

~Kcom#

5 Ruang R ad ng Reso r,g 4

4 3 312ij35 4HJ 312635 0-93 3 263!

J l1?!i35 43 q1 l ?6l5 Te,99 Cs 137(Bc.'.a)

Te-9 C. 131! r ',)

~c-'l9 Cu* 11ar Eo,n,.,,,., ID C

'&d 81 h,

\\'

IJl 0 02.49 CID I~ Pi) 0 0>46 C/0 1*

J 0 0471 CIO 1 P,)

0 CIO ( Pr) o CID<* Pr) 0 CID( P,)

0 C/0(4 P,j 0

00( Pi 1273$7 273 7 Cs 12' '

U3b/C 177:156

'17357 Cs-127356 OCR viw, f l Huol*.r A

,. I Serial N mbe, 2!>0176 S rl

~umber 312'63 Souroo 10 Pulser g97 8 Pul r e,~

r 87~

715 Volts 0 I ~*a* 05 20 t.rplres Ma* 05, 202~

OC

¥,M, 20241 IO II h rl Survey Umt STR-105-03 Page 22 of29 Reactor Compartment (RC)- Lower Level, Drain Wells

S1vANNA11Technical Staff Survey Unit Release Record C

b lion Curt,rl RSCS 0 Num I: 2.50!51'7000 - 202403~

Cont S

10.. Ir ln&trument Lud Jm Aodel 02 Se br NH 7-'I Pr Mod I er11I ~um 2!.03~H7 Sarlal Num 421*11 Tes*1

,__....,s'--oo l<cpm AUTO IIVTO AUTO AJTO 43 934a1411 4 9:l 421411

43. 3421411 4l 34 1<111 4~

4;?!41 43-'i:1421 4 I Ca

!dl:lyN w g L udtu 4J. 9 Pf'7 clslon Ch Tc L3

--'---..:...::~=-"---L~ -

4.!l cpm 4.99 kcpm Accuracy Check T

etValuc lc.99 Cs 137* Bet*J Cs-la)

Effit one NlST Sour~ 10 0 0 61 C/0 (.t P1) 127J57 Cs-137(Bota) 0 026(i CID (4

1) 1 7 Tc.-S9
0.

<l8 CID (4 I I)

  • 21357 Cs 137\\Beta) 0.0218 CID(' I) n1 Tc..99 314 Abow Grat 0 \\568 CID (4 Pi)
  • 27 57 c.-1 7(B~la)

On Conl3(:I 0 1002 CID (4 P1) 127356 Tc-99 0 Com ct o 1176 C/0 {4 J 314 * /It:

soi.rec 0.0E C/0 ~4:..;P~*,._) ___ :..,_:_=c..c..::..=.:::..... ___.;...:~==-...:::*..::'4_" Allo\\

=:.:.::'B_:S:::o:::_JIUI QC R,e" By ~atltl w i.nter II,,./

I Mar 0 2024 C*P r Jla, 04, o;,

QC Dial

,lar05 4

t nc b rl Survey Umt STR-105-03 Page23 of29 Reactor Compartment (RC)- Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record

'1 - - -- i rt - Static Data Count Rate Total Weighted Eff Meter ID

  • Measurement ID (cpm)

(c/d) 25017651 STR-105-03-01 90 0.0885 25017651 STR-105-03-02 51 0.0885 25017651 STR-105-03-03 48 0.0885 25017651 STR-105-03-04 69 0.0885 25017651 STR-105-03-05 63 0.0885 25017651 STR-105-03-06 54 0.0885 25017651 STR-105-03-07 61 0.0885 25017651 STR-105-03-08 64 0.0885 25017651 STR-105-03-09 274 0.0885 25017651 STR-105-03-10 295 0.0885 25017651 STR-105-03-11 129 0.0885 25017651 STR-105-03-12 82 0.0885 25017651 STR-105-03-13 45 0.0885 25017651 STR-105-03-14 348 0.0885 25017651 STR-105-03-15 61 0.0885 25017651 STR-105-03-16-J 112 0.0885 25017651 STR-105-03-17-J 75 0.0885 25035147 STR-105-03-06-D 69 0.1023 Note: Meter IDs 2501765land 25035147 are connected to a Ludlum model 43-93 detector with an area of 100 cm2.

Survey Unit STR-105-03 Page 24 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAH Technical Staff Survey Unit Release Record Scan ID SA-01 SA-02 SA-03 SA-04 SA-05 SA-06 SA-07 SA-08 SA-09 SA-10 SA-11 SA-12 - Scan Data Total Min/Max Range Average Weighted eff Meter ID (cpm)

(com)

(c/d) 25017651 32/147 89.5 0.0642 25017651 28/90 59.0 0.0642 25017651 19/90 54.5 0.0642 25017651 19/106 62.5 0.0642 25017651 22/63 42.5 0.0642 25017651 26/54 40.0 0.0642 25017651 123/283 203.0 0.0642 25017651 35/232 133.5 0.0642 25017651 29/84 56.5 0.0642 25017651 70/102 86.0 0.0642 25017651 45/161 103.0 0.0642 25017651 40/117 78.5 0.0642 Note: Meter ID 25017651 is connected to a Ludlum model 43-93 detector with an area of 100 cm2.

Survey Unit STR-105-03 Page 25 of29 Reactor Compartment (RC) - Lower Level, Drain Wells

SAVANNAHTechnical Staff Survey Unit Release Record - Quality Control Assessment Measurement Value ( dpm/100 cm2)

Initial measurement 610.22 Replicate measurement 674.41 Average 642.32 Absolute Value of the difference 64.19 Condition Absolute value of the Control Limit (dpm/100 cm2) difference (dpm/100 cm2)

Average < 52,300 64.19 11087.6 Survey Unit STR-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells Result Pass Page 26 of29

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

(dpm/100 cm2)

STR-105-03-01 1017.03 68682.97 STR-105-03-02 576.32 69123.68 STR-105-03-03 542.42 69157.58 STR-105-03-04 779.73 68920.27 STR-105-03-05 711.92 68988.08 STR-105-03-06 610.22 69089.78 STR-105-03-07 689.32 69010.68 STR-105-03-08 723.22 68976.78 STR-105-03-09 3096.30 66603.70 STR-105-03-10 3333.61 66366.39 STR-105-03-11 1457.75 68242.25 STR-105-03-12 926.63 68773.37 STR-105-03-13 508.52 69191.48 STR-105-03-14 3932.53 65767.47 STR-105-03-15 689.32 69010.68 STR-105-03-16-J 1265.64 68434.36 STR-105-03-17-J 847.53 68852.47 Parameter Result Number of Measurements 17 NumberofS+

17 Critical Value 12 Meets I Doesn't Meet Acceptance Criteria Meets Survey Unit STR-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells Sign

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1

+1 Page 27 of29

SAVANNAHTechnical Staff Survey Unit Release Record - Graphical Presentations Quantile Plot of Gross Activity Concentration 4300 3800

"'a 3300 u

g 2800

...... a

.g.2300 u

i::l 1800 0 u u 1300 800 300 0%

10%

20%

30%

40%

50%

60%

70%

80%

Survey Unit STR-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells j

90%

100%

Page 28 of29

SAVANNAH Technical Staff Survey Unit Release Record Histogram Survey Unit Number: STR-105-03 Reactor Compartment (RC)-Lower-Level Survey Unit Name: Drain Wells 12 JO 8

4 2

0 937 1365 1793 2221 2649 3077 Upper end value (dpm/100 cm2)

Survey Unit STR-105-03 Reactor Compartment (RC) - Lower Level, Drain Wells 3505 3933 Page 29 of29

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