ML19077A056

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Submittal of Final Status Survey (FSS) Final Report, Phase 2, Part 1 - Unit 2 Tendon Buttress Pits Survey Unit 06108
ML19077A056
Person / Time
Site: Zion  File:ZionSolutions icon.png
Issue date: 01/09/2019
From: Giza P
ZionSolutions
To:
Office of Nuclear Material Safety and Safeguards
References
ZS-2019-0017
Download: ML19077A056 (65)
v • d • e


Text

ZION STATION RESTORATION PROJECT FINAL STATUS SURVEY RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108

FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 PREPARED BY / DATE: Patricia .Giza 1/9/2019 Radiological Engineer REVIEWED BY / DATE: R.F Decker 1/9/2019 Radiological Engineer APPROVED BY / DATE: D. Wojtkowiak 1/9/2019 C/LT Manager

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 TABLE OF CONTENTS

1. EXECUTIVE

SUMMARY

....................................................................................................4

2. SURVEY UNIT DESCRIPTION ..........................................................................................5
3. CLASSIFICATION BASIS ...................................................................................................5
4. DATA QUALITY OBJECTIVES (DQO) ............................................................................5
5. SURVEY DESIGN .................................................................................................................9
6. SURVEY IMPLEMENTATION ........................................................................................12
7. SURVEY RESULTS ............................................................................................................13
8. QUALITY CONTROL ........................................................................................................16
9. INVESTIGATIONS AND RESULTS ................................................................................16
10. REMEDIATION AND RESULTS......................................................................................16
11. CHANGES FROM THE SURVEY PLAN ........................................................................16
12. DATA QUALITY ASSESSMENT (DQA) .........................................................................17
13. ANOMALIES .......................................................................................................................17
15. CONCLUSION .....................................................................................................................17
16. REFERENCES .....................................................................................................................18
17. ATTACHMENTS .................................................................................................................18 ATTACHMENT 1 - FIGURE AND MAPS ........................................................................19 ATTACHMENT 2 - QC DATA ...........................................................................................22 ATTACHMENT 3 - ISOCS ANALYTICAL REPORTS..................................................24 LIST OF TABLES Table 1 - Dose Significant Radionuclides and Mixture................................................................... 7 Table 2 - Base Case and Operational DCGLs ................................................................................. 8 Table 3 - Surrogate Ratios ............................................................................................................. 10 Table 4 - Investigation Levels ....................................................................................................... 11 Table 5 - Synopsis of Survey Design ............................................................................................ 12 Table 6 - Unit 2 Tendon Buttress Pits - Measured Concentrations of ROC for FSS .................... 14 Table 7 - Unit 2 Buttress Pits- Statistical Quantities ..................................................................... 16

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108

1. EXECUTIVE

SUMMARY

This Final Status Survey (FSS) Release Record for Survey Unit #B3-06108A, Unit 2 Tendon Buttress Pits has been generated for the Zion Station Restoration Project (ZSRP) in accordance with ZionSolutions procedure ZS-LT-300-001-005, Final Status Survey Data Reporting (Reference 1) and satisfies the requirements of Section 5.11 of the Zion Station Restoration Project License Termination Plan (LTP) (Reference 2).

The FSS Sample Plan #B3-06108AF was developed in accordance with ZionSolutions procedure ZS-LT-300-001-001, Final Status Survey Package Development (Reference

3) the ZSRP LTP, and guidance from NUREG-1575, Revision 1, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) (Reference 4).

In April of 2016, an FSS was conducted on the Turbine Building Basement structure.

The Sample Plan design for the FSS of the Turbine Building did not include the surface area of the Unit 1 and Unit 2 Tendon Buttress Pits. A separate Sample Plan was written to include six (6) additional judgmental measurements to represent the surface area of each of the Tendon Buttress Pits. The result of each ISOCS measurement will be added as per the LTP Chapter 5, section 5.5.6.1.

FSS was performed in the Unit 2 Tendon Buttress Pits to demonstrate that the concentrations of residual radioactivity were equal to or below site-specific Derived Concentration Guideline Levels (DCGL) corresponding to the dose criterion in 10 CFR 20.1402. The Unit 2 Tendon Buttress Pits have a MARSSIM Classification of 3.

A Sample Plan was designed based upon the use of the Sign Test as the nonparametric statistical test for compliance. Both the Type I () and Type II () decision rates were set at 0.05. The Canberra In situ Object Counting System (ISOCS) was selected as the primary instrument used to perform FSS. The Tendon Buttress Pits were surveyed as biased areas using judgmental locations. These results of the judgmental measurements were added to the systematic mean of the Turbine Building Basement survey. Six (6) judgmental ISOCS measurements with a Field of View (FOV) of 28 m2 were originally designed for each Buttress Pit floors with the possibility of one (1) additional measurement taken on the wall if accessible. After the engineer walk down and visual inspection, it was decided to revise the original Circular Plane geometry to the Room geometry, which decreased the FOV from 28 m2 to 18.7 m2. See ZionSolutions TSD 14-022 Use of In-Situ Gamma Spectroscopy for Final Status Survey of End State Structures (Reference 5). Based on the new FOV of 18.70 m2 for each judgmental ISOCS measurement, the total surface area coverage for the measurements equated to 112 m2 or approximately 7% of the total surface area of the Unit 2 Tendon Buttress Pits.

The results from each judgmental ISOCS measurement taken in the Unit 2 Tendon Buttress Pits indicate a Sum-of-Fraction (SOF), considering the concentration of all

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 applicable Radionuclides of Concern (ROC), either by direct measurement or by inference, is less than 0.1 when applying the respective Operational Derived Concentration Guideline Levels (OpDCGL) for the Turbine Building Basement from ZionSolutions TSD 17-004, Operational Derived Concentration Guideline Levels for FSS (Reference 6). Therefore, the null hypothesis is rejected and the Unit 2 Tendon Buttress Pit survey is acceptable for unrestricted release.

2. SURVEY UNIT DESCRIPTION The Tendon Buttress Pits are bound by the interior surface of the structure from 591 foot elevation down to the 565 foot elevation. The survey unit consists of the Containment concrete exterior and buttress, tendon steel end caps protruding from the buttress faces, perimeter walls and the wall dividing the Tendon Buttress Pits into chambers. The Tendon Buttress Pits are 26 feet deep and 4 feet wide with angled side walls which limits access. There are six entrances (see Attachment 1- Figures and Maps). In the end-state condition, the portions of the structures above the 588 foot elevation will be removed and disposed of as waste. The remaining void below the 588 foot elevation will be backfilled with a combination of clean demolition debris and clean fill.
3. CLASSIFICATION BASIS The Turbine Building Basement Survey Unit 06100 was classified in accordance with ZionSolutions procedure ZS-LT-300-001-002, Survey Unit Classification (Reference 7). The Tendon Buttress Pits were not included in the original Sample Plan #

B306100AS, but are part of the Turbine Building survey unit.

Based on information from the Zion Station Historical Site Assessment (HSA)

(Reference 8), the initial classification for Turbine Building Basement 06100 Survey Unit was Class 3. Although the Unit 2 Tendon Buttress Pits were inaccessible during site characterization in 2013, the results of environmental monitoring of radiological effluents indicate that the residual radioactivity in the Tendon Buttress Pits was minimal, supporting the classification.

4. DATA QUALITY OBJECTIVES (DQO)

Final Status Survey planning and design hinges on coherence with the 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 ZSRP LTP. The appropriate design for a given survey will be developed using the DQO process as outlined in Appendix D of MARSSIM.

The DQO process incorporated hypothesis testing and probabilistic sampling distributions to control decision errors during data analysis. Hypothesis testing is a

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 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 plan, 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 #B3-06108 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).

ZionSolutions TSD 11-001, Potential Radionuclides of Concern during the Decommissioning of Zion Station (Reference 9) established the basis for an initial suite of potential ROC for the decommissioning of the Zion Nuclear Power Station (ZNPS).

LTP Chapter 2 provides detailed characterization data that described contamination levels in the basements. The survey data for this basement is based on core samples obtained at biased locations with elevated contact dose rates and/or evidence of leaks/spills and analyzed for the presence of plant-derived radionuclides.

ZionSolutions TSD 14-019, Radionuclides of Concern for Soil and Basement Fill Model Source Terms (Reference 10) evaluates the results of the concrete core analysis data from the Containments and Auxiliary Building and refines the initial suite of radionuclides potential ROC by evaluating the dose significance of each radionuclide.

LTP Chapter 6, section 6.5.2 discusses the process used to derive the ROC for the decommissioning of ZNPS, including the elimination of insignificant dose contributors (IC) from the initial suite. LTP section 6.5.2 also states that the Auxiliary Basement ROC and the IC percentage of 5% for adjusting ROC DCGLs will also be applied to all other Basements with the exception of the Containments. This includes the Turbine Building basement survey unit. Table 1 presents the ROC from the Auxiliary Basement structural surfaces and the normalized fractions based on the radionuclide mixture.

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 Table 1 - Dose Significant Radionuclides and Mixture

% of Total Activity Radionuclide (normalized)(1)

Co-60 0.92 Cs-134 0.01 Cs-137 75.32 Ni-63 23.71 Sr-90 0.05

1. Based on maximum percent of total activity from Table 20 of TSD 14-019, normalized to one for the dose significant radionuclides.

A fundamental precursor to survey design is to establish a relationship between the release criteria and some measurable quantity. This is done through the development of DCGLs. The DCGLs represent average levels of radioactivity above background levels and are presented in terms of surface or mass activity concentrations. Chapter 6 of the LTP describes in detail the modeling used to develop the DCGLs for structures.

The End State Basements will be comprised of steel and/or concrete structures which will be covered by at least three feet of clean soil and physically altered to a condition which would not realistically allow the remaining structures, if excavated, to be occupied. The exposure pathways in the BFM are associated with residual radioactivity in floors and walls that is released through leaching into water contained in the interstitial spaces of the fill material. The BFM assumes that the inventory of residual radioactivity in a given building is released either instantly or over time by diffusion, depending on whether the activity is surficial or volumetric, respectively. The activity released into the fill water will adsorb onto the clean fill, as a function of the radionuclide-specific distribution coefficients, resulting in equilibrium concentrations between the fill and the water.

Consequently, the only potential exposure pathways after backfill, assuming the as-left geometry, are associated with the residual radioactivity in the water contained in the fill.

The final outputs of the BFM are the Basement Derived Concentration Guideline Levels (DCGL), in units of pCi/m2, which are calculated using the BFM GW and BFM Drilling Spoils Dose Factors (LTP Chapter 6, Tables 6-24 and 6-25). The DCGLs for basement structure surfaces are calculated separately for the GW and Drilling Spoils scenarios and for the summation of both scenarios. The summation DCGL is designated as the Base Case DCGL and is used during FSS to demonstrate compliance (analogous to the DCGLW as defined in MARSSIM). The Base Case DCGLs are radionuclide-specific

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 concentrations that represent the 10 CFR 20.1402 dose criterion of 25 mrem/year and are calculated for each ROC and each backfilled Basement.

When applied to structures, the DCGLs are expressed in units of activity per unit of area (pCi/m2). The unity rule is applied when there is more than one ROC. The measurement results for each singular ROC present in the mixture are compared against their respective DCGL to derive a dose fraction.

The Base Case DCGLs for the unrestricted release of the Turbine Building survey unit (including the Tendon Buttress Pits) are provided in Table 2. The IC dose percentage of 5% was used to adjust the Turbine Building Base Case DCGLs to account for the dose from the eliminated IC radionuclides.

Each radionuclide-specific Base Case DCGL is equivalent to the level of residual radioactivity (above background levels) that could, when considered independently, result in a TEDE of 25 mrem per year to an AMCG. To ensure that the summation of dose from each source term is 25 mrem/year or less after all FSS is completed, the Base Case DCGL is reduced based on an expected, or a priori, fraction of the 25 mrem/year dose limit from each source term. The reduced DCGLB or Operational DCGL can be related to the Base Case DCGL as an expected fraction of dose based on an a priori assessment of what the expected dose should be based on the results of site characterization, process knowledge and the extent of planned remediation. The Operational DCGL is then used as the DCGL for the FSS design of the survey unit (calculation of surrogate DCGLs, investigations levels, etc.). Details of the Operational DCGLs derived for each dose component and the basis for the applied a priori dose fractions are provided in TSD 17-004. The Operational DCGLB for FSS in the Unit 2 Tendon Buttress Pits are also provided in Table 2.

Table 2 - Base Case and Operational DCGLs Base Case Turbine Operational Turbine Radionuclide Building DCGLs Building DCGLs pCi/m2 pCi/m2 Co-60 7.03E+07 5.98E+06 Ni-63 2.18E+09 1.85E+08 Sr-90 7.74E+05 6.58E+04 Cs-134 1.59E+07 1.35E+06 Cs-137 2.11E+07 1.79E+06 Instrument DQOs included a verification of the ability of the survey instrument to detect the radiation(s) of interest relative to the Operational DCGL. The Canberra ISOCS was selected as the primary instrument used to perform FSS of basement surfaces. Survey instrument response checks were required prior to issuance and after the instrument had

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 been used. Control and accountability of survey instruments was required to assure the quality and prevent the loss of data.

As part of the DQOs applied to laboratory processes, analysis results were reported as actual calculated results. The actual recorded value was used as the recorded FSS result for measurement and/or sample values that are less than MDC. Negative values were recorded as zero. Results were not reported as less than MDC. Sample report summaries included unique sample identification, analytical method, radionuclide result uncertainty, laboratory data qualifiers, units, and the observed MDC.

In accordance with the LTP, for laboratory analysis, MDCs less than 10% of the Operational DCGL were preferable while MDCs up to 50% of the Operational DCGL were acceptable. The maximum acceptable MDC for measurements obtained using field instruments was 50 percent of the applicable Operational DCGL.

5. SURVEY DESIGN The level of effort associated with planning a survey is based on the complexity of the survey and nature of the hazards. Guidance for preparing FSS plans is provided in procedure ZS-LT-300-001-001. The procedure states that a FSS Class 3 survey unit shall have between 1% and 10% areal scan coverage. Due to safety concerns identified by a walkdown of the Tendon Buttress Pits, an areal coverage of 5% was selected. The ISOCS Room geometry was selected in accordance with TSD 14-022 and the original FOV of 28 m2 was adjusted to a box FOV of 18.70 m2 for total surface scan area of approximately 112 m2.

Sample size determination for the FSS of Turbine Building basement is addressed in LTP Chapter 5, section 5.5.2.2. The surface areas of the Tendon Buttress Pits were not included in the surface area that was surveyed as the Turbine Building basement.

Consequently, the source term from biased judgmental FSS results from the surface of the Tendon Buttress Pits will be added to the Turbine Building. This is addressed in LTP Chapter 5, Table 5-22. The FSS data taken in the Turbine Building passed Sign test. The mean dose contribution for the Turbine Building is then calculated using the mean concentrations from the FSS of the Turbine Building walls and floors plus the mean of the judgmental samples taken in other portions of the Turbine Building survey unit (e.g.

the Circulating Water Intake Pipe, the Circulating Water Discharge Pipe and the Buttress Pits/Tendon Tunnels) on an area-weighted basis. The total basement area used in the weighted average calculation is the adjusted surface area used to calculate the DCGLs in LTP Chapter 6, section 6.6.8. The adjusted area for the Turbine Building from LTP Chapter 5, Table 5-23 is 27,135 m2. In accordance with TSD 14-014, End State Surface Areas Volumes and Source Terms of Ancillary Bldgs, (Reference 11), the total surface

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 area of one Tendon Buttress Pit is 2,863 ft2 or 266 m2. The total surface area of all six Unit 2 Tendon Buttress Pits is 1,596 m2.

The area-weighted SOF is calculated in accordance with LTP Chapter 5, Equation 5-8, which is reproduced as follows. The SOFBi,B variable in the equation is based on the mean of the judgmental samples.

Equation 1

, = ,

=1 where:

SOFB,B = total surface SOF including all surface survey units in basement (B)

SASUi,B = surface area of survey unit (i) in basement (B)

SAAdjust,B = adjusted surface area for DCGL calculation (Table 5-23) for basement (B)

SOFBi,B = SOFB for survey unit (i) in basement (B)

This sample plan for the Unit 2 Tendon Buttress pits consisted of six judgmental locations, one on the floor of each Buttress Pit. Attachment 1, Figures and Maps, illustrates the locations of the ISOCS measurements taken.

The DQO process determined that Co-60, Ni-63, Sr-90, Cs-134, Cs-137 would be the ROC in survey unit #B3-06108. During FSS, concentrations for Hard-to-Detect (HTD)

ROC Ni-63 and Sr-90 are inferred using a surrogate approach specified in LTP section 5.2.11. Cs-137 is the principle surrogate radionuclide for Sr-90 and Co-60 is the principle surrogate radionuclide for Ni-63. The mean, maximum and 95% Upper Confidence Level (UCL) of the surrogate ratios for concrete core samples taken in the SFP/Transfer Canal basement were calculated in TSD 14-019 and are presented in LTP Chapter 5, Table 5-15, which is reproduced in Table 3 below.

Table 3 - Surrogate Ratios Auxiliary Building Ratios Mean Max 95%UCL Ni-63/Co-60 44.143 180.450 154.632 Sr-90/Cs-137 0.001 0.002 0.002 For the FSS of Survey Unit #B3-06108, the surrogate Operational DCGLs for Co-60 and Cs-137 are based on the maximum ratios from Table 3.

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 Equation 1 1

=

1 2 3

+ + +

2 3 Where: DCGLSur = Surrogate radionuclide DCGL DCGL2,3n = DCGL for radionuclides to be represented by the surrogate Rn = Ratio of concentration (or nuclide mixture fraction) of radionuclide n to surrogate radionuclide Using the Operational DCGLs for the Turbine Building presented in Table 2 and the maximum ratios from Table 3, the following surrogate calculations were performed for FSS Unit #B3-06108; Equation 2 1

(137) = = 1.70 + 06 /2 1 0.002

+

1.79 + 06(137) 6.58 + 04(90)

The surrogate Operational DCGL that was used for Cs-137 in FSS Unit #B3-06108 for direct comparison of sample results to demonstrate compliance is 1.70E+06 Ci/m2.

Equation 3 1

(60) = = 8.75 + 05 /2 1 180.45

+

5.98 + 06(60) 1.85 + 08(63)

The surrogate Operational DCGL that was used for Co-60 in FSS Unit #B3-06108 for direct comparison of sample results to demonstrate compliance is 8.75E+05 Ci/m2.

For this Class 3 basement structure survey units the Investigation Levels for ISOCS measurement results are those levels specified in LTP Chapter 5, Table 5-25 and are reproduced below in Table 4.

Table 4 - Investigation Levels Classification Direct Investigation Levels Class 3 >0.5 Operational DCGL

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 In compliance with ZS-LT-01, Quality Assurance Project Plan (QAPP) for Characterization and Final Status Survey (Reference 12), replicate measurements were to be performed on 5% of the static measurement locations.

Table 5 provides a synopsis of the survey design for Survey Unit #B3-06108.

Table 5 - Synopsis of Survey Design FEATURE DESIGN CRITERIA BASIS Survey Unit Surface 1,596 m2 TSD-14-014, Table 63 Area Number of Static 6 judgmental measurements w/ FOV of ZS-LT-300-001-001, Measurements 18.70 m2 for 7% areal coverage Attachment 4 Measurement 1 measurement on the floor of each ZS-LT-300-001-001, Spacing buttress pit Attachment 4

  • Co 5.98E+06 pCi/m2
  • Cs-134 - 1.35E+06 pCi/m2 Operational DCGLs for Turbine DCGLs
  • Cs-137 - 1.79E+06 pCi/m 2 Building
  • Ni 1.85E+08 pCi/m2 (LTP Chapter 5, Table 5-4)
  • Sr 6.58E+04 pCi/m2 Measurement

>0.5 Operational DCGLW (LTP Chapter 5, Table 5-25)

Investigation Level Survey Area ZS-LT-300-001-001, 112 m2 for ~7% surface coverage Coverage Attachment 4 QC 5 % Duplicate ISOCS Measurements (LTP Chapter 5, section 5.9)

6. SURVEY IMPLEMENTATION For the judgmental measurements performed in Survey Unit #B3-06108, compliance with the unrestricted release criteria was demonstrated by direct comparison of the ISOCS measurement results to their respective OpDCGL.

A walk down was performed by FSS personnel on 06/11/18. Access into the Tendon Buttress Pits is via a set of ladders. The surfaces are very slippery due to the presence of water and tendon grease. Due to safety concerns pertaining to safe personnel access, no turnover surveys were performed prior to accepting the Unit 2 Tendon Buttress Pits for FSS.

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 Field Logs (ZS-LT-300-001-001 Attachment 14) were used to document field activities and other information pertaining to the performance of the FSS. Daily briefings were conducted to discuss the expectations for job performance and to review safety aspects of the job.

ZionSolutions TSD 14-022 provides the initial justification for the selection of reasonably conservative geometries for efficiency calibrations for the ISOCS based on the physical conditions and distribution of activity. All ISOCS measurements were acquired using approved geometries.

The ISOCS detector was positioned vertical to the floor surface at the center-point of each selected measurement location. The Room geometry utilizes a 180 degree FOV (collimator removed) and the measurement location is at the top center of the room.

This orientation corresponded to a nominal FOV of 18.70 m2.

The measured activity for each gamma-emitting ROC (and any other gamma emitting radionuclide that was positively detected by ISOCS) was recorded (in units of pCi/m2).

Background was not subtracted from any measurement. A SOF calculation was performed for each measurement by dividing the reported concentration of each ROC by the Operational DCGL for each ROC to derive an individual ROC fraction. The individual ROC fractions were then summed to provide a total SOF value for the measurement.

One duplicate measurement was taken with the ISOCS in the second Tendon Buttress Pit (designated as Grid #2). This location was randomly selected using the Microsoft Excel RANDBETWEEN function. The number of replicate measurements satisfies the requirement that a minimum of 5% percent of the number of measurements that will be used for non-parametric statistical testing be selected for additional QC evaluation.

7. SURVEY RESULTS The SOF or unity rule was applied to the data used for the survey planning, data evaluation and statistical tests for basement surfaces since multiple radionuclide-specific measurements were performed and concentrations inferred based on known relationships.

The application of the unity rule served to normalize the data to allow for an accurate comparison of the results from the six judgmental measurements to the release criteria.

When the unity rule was applied, the DCGLw (used for the nonparametric statistical test) becomes one (1). The Base Case basement structure DCGLs (BcDCGLB), is directly analogous to the DCGLW as defined in MARSSIM. The use and application of the unity rule was performed in accordance with section 4.3.3 of MARSSIM.

As previously stated, as the extent of this survey was the acquisition of judgmental measurements at biased locations, compliance was demonstrated by direct comparison of

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 each measurement result to the release criterion. For building surfaces, areas of elevated activity were defined as any area identified by measurement/sample (systematic or judgmental) that exceeded the Operational DCGL but was less than the Base Case DCGL. Any area that exceeded the Base Case DCGL would have required remediation.

This was not the case for the FSS of the Unit 2 Tendon Buttress Pits as all measurements taken, when compared against the OpDCGL was less than a SOF of one. The ISOCS measured concentration results from the Unit 2 Tendon Buttress Pits are listed in Table 6.

Table 7 presents the mean concentration of the judgmental measurements and SOF when compared against BcDCGL.

Table 6 - Unit 2 Tendon Buttress Pits - Measured Concentrations of ROC for FSS MEASUREMENT ROC CONCENTRATIONS Co-60 Ni-63(1) Sr-90(1) Cs-134 Cs-137 MEASUREMENT ID SOF(2)

(pCi/m2) (pCi/m2) (pCi/m2) (pCi/m2) (pCi/m2)

B3-06108AF-JFC-001-GD 0.00E+00 0.00E+00 9.06E+00 3.88E+03 4.53E+03 0.0055 B3-06108AF-JFC-002-GD 3.94E+03 7.11E+05 1.23E+01 0.00E+00 6.13E+03 0.0081 B3-06108AF-JFC-003-GD 5.66E+03 1.02E+06 1.37E+01 1.05E+03 6.86E+03 0.0113 B3-06108AF-JFC-004-GD 2.79E+03 5.03E+05 4.68E+00 2.39E+04 2.34E+03 0.0223 B3-06108AF-JFC-005-GD 1.54E+03 2.78E+05 1.38E+01 3.25E+03 6.90E+03 0.0082 B3-06108AF-JFC-006-GD 9.14E+02 1.65E+05 1.03E+01 6.10E+00 5.13E+03 0.0041 Min 0.00E+00 0.00E+00 4.68E+00 0.00E+00 2.34E+03 4.07E-03 Median 2.17E+03 3.91E+05 1.13E+01 2.15E+03 5.63E+03 8.17E-03 Maximum 5.66E+03 1.02E+06 1.38E+01 2.39E+04 6.90E+03 2.23E-02 STDEV 2.09E+03 3.77E+05 3.47E+00 9.23E+03 1.74E+03 6.54E-03 Skew 5.19E-01 5.19E-01 -1.07E+00 2.28E+00 -1.07E+00 1.71E+00 (1) Inferred concentration (2) Compared against OpDCGL

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 Figure 1 Unit 2 Tendon Buttress Pits

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 Table 7 - Unit 2 Buttress Pits- Statistical Quantities INDIVIDUAL MEASUREMENT METRICS Total Number of Judgmental Measurements = 6 Number of Quality Control Measurements = 1 Total Number of Measurements = 7 Mean Measurement SOF = 0.0099 Max Judgmental Measurement SOF = 0.0223 Number of Judgmental Measurements with SOF > = 1 = 0 STATISTICAL QUANTITIES AVG AVG MEAN MEDIAN MAX MIN BcDCGL DOSE ROC SOF PER PER ROC (pCi/m2) (pCi/m2) (pCi/m2) (pCi/m2) (pCi/m2) ROC Co-60 2.47E+03 2.17E+03 5.66E+03 0.00E+00 2.09E+03 7.03E+07 0.0000 0.0009 Ni-63 4.46E+05 3.91E+05 1.02E+06 0.00E+00 3.77E+05 2.18E+09 0.0002 0.0051 Sr-90 1.06E+01 1.13E+01 1.38E+01 0.00E+00 3.47E+00 7.74E+05 0.0000 0.0003 Cs-134 5.35E+03 2.15E+03 2.39E+04 0.00E+00 9.23E+03 1.59E+07 0.0003 0.0084 Cs-137 5.32E+03 5.63E+03 6.90E+03 2.34E+03 1.74E+03 2.11E+07 0.0003 0.0063 Mean SOF for Survey Unit = 0.0008 Dose (based on Mean SOF) = 0.0210 mrem/yr

8. QUALITY CONTROL The implementation of required QC measures included the collection of one additional ISOCS measurements in Survey Unit #B3-06108 for replicate measurement analysis.

The ISOCS gamma spectroscopy reports for the duplicate measurements are presented in Attachment 4. The duplicate ISOCS measurement met the required acceptance criteria.

The completed Duplicate Sample Assessment Form is included in Attachment 2 of this Release Record.

9. INVESTIGATIONS AND RESULTS No measurements were taken for an investigation during the performance of FSS in this survey unit.
10. REMEDIATION AND RESULTS No remediation was performed in this Survey Unit.
11. CHANGES FROM THE SURVEY PLAN There were no addendums to the FSS plan.

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108

12. DATA QUALITY ASSESSMENT (DQA)

In accordance with procedure ZS-LT-300-001-004, the DQOs, sample design, and data were reviewed for completeness, accuracy, and consistency. Documentation was complete and legible. The FSS unit was properly classified as Class 3. All measurement results were individually reviewed and validated. The FOV for the number of measurements taken was sufficient to meet the requirement of 5% areal coverage of surfaces for a Class 3 survey unit. The instrumentation used to perform the FSS were in calibration, capable of detecting the activity with an adequate MDC and successfully response checked prior to and following use. An adequate number of replicate measurements were taken and the results meet the acceptance criteria as specified in the QAPP.

The analytical results of the 6 judgmental measurements were less than a SOF of one when directly compared against the OpDCGL.

The preliminary data review consisted of calculating basic statistical quantities (e.g.,

mean, median, standard deviation). All data was considered valid and the values reported below the MDC, and values with uncertainties that exceeded two standard deviations.

13. ANOMALIES No anomalies were observed during the performance or analyses of the survey.
15. CONCLUSION Six (6) judgmental measurements were taken, one in each of the Unit 2 Tendon Buttress Pits. The FOV of each measurement included the floor and three walls. The total surface area of all of the six Unit 2 Tendon Buttress Pits is 1,596 m2. The FOV for the box Room geometry used for the ISOCS measurement was 18.70 m2, which equated to an areal coverage of 112 m2 or 7% of the surface area of the Buttress Pits.

All of the measurements were below a SOF of 0.5, when compared to the OpDCGLB.

The average SOF for the survey unit was 0.0008. The requirements for a Class 3 survey unit have been met.

The calculated dose from the mean ROC concentrations detected by these judgmental measurements is 0.0210 mrem/yr.

The conclusion of this Release Record is that when the six judgmental measurement results are added to the mean of the Turbine Building FSS, the Turbine Building FSS unit will pass FSS.

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108

16. REFERENCES
1. ZionSolutions Procedure ZS-LT-300-001-005, Final Status Survey Data Reporting
2. Zion Station Restoration Project License Termination Plan (LTP)
3. ZionSolutions Procedure ZS-LT-300-001-001, Final Status Survey Package Development
4. NUREG-1575, Revision 1, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM)
5. ZionSolutions TSD 14-022 Use of In-Situ Gamma Spectroscopy for Final Status Survey of End State Structures
6. ZionSolutions TSD 17-004, Operational Derived Concentration Guideline Levels for FSS
7. ZionSolutions Procedure ZS-LT-300-001-002, Survey Unit Classification
8. Zion Station Historical Site Assessment (HSA)
9. ZionSolutions TSD 11-001, Potential Radionuclides of Concern during the Decommissioning of Zion Station
10. ZionSolutions TSD 14-019, Radionuclides of Concern for Soil and Basement Fill Model Source Terms
11. ZionSolutions TSD 14-014, End State Surface Areas Volumes and Source Terms of Ancillary Bldgs
12. ZionSolutions ZS-LT-01, Quality Assurance Project Plan (QAPP) for Characterization and Final Status Survey
17. ATTACHMENTS Attachment 1 - Figure and Maps Attachment 2 - QC Data Attachment 3 - ISOCS Analytical Reports

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 ATTACHMENT 1 - FIGURE AND MAPS

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 ATTACHMENT 2 - QC DATA

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 UNIT 2 Tendon Buttress Pits- QC Agreement Duplicate Sample Assessment Form Survey Area #: 6100 Survey Unit # 06108 Survey Unit Name: Unit 2 Buttress Pits Sample Plan#: B1-06108A-F Sample

Description:

Comparison of systematic and QC ISOCS measurements of concrete at GRID #2. The standard measurement is ID as B3-06108AF-JFC-002-GD. The comparison measurement is ID as B3-06108AF-QFC-002-GD STANDARD COMPARISON Activity Activity Standard Agreement Standard Comparison Acceptable Radionuclide Value Resolution Value Error Range Error Ratio (Y/N)

(pCi/m2) (pCi/m2)

K-40 7.08E+05 1.00E+05 7 0.5-2.0 6.66E+05 9.96E+04 1.1 Y Comments/Corrective Actions: None Table is provided to show acceptance criteria used to assess split samples.

Performed by: Patsy Giza Date: Reveiwed by: Date:

6/26/2018 6/26/2018

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FSS RELEASE RECORD UNIT 2 TENDON BUTTRESS PITS SURVEY UNIT 06108 ATTACHMENT 3 - ISOCS ANALYTICAL REPORTS

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