ML043290296
| ML043290296 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/17/2004 |
| From: | Vanags U Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FB-0500-03, Rev 0 | |
| Download: ML043290296 (20) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-0500 TURBINE BUILDING FOOTPRINT SURVEY UNIT 3 if // ODate:
Prepared By: /Ak F
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Reviewed By: ,-cs, , /j_-_9_-_____
Independent Reviewer -
Signature Aa le R 4fi, //
prited Name Approved By: r Date: / t pitende pSg jnature Printed Name Date:
Approved By: .1S L/ 3H-,- 7/6' IfSS, IA0P - Signature-Printed Name
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-0500 TURBINE BUILDING FOOTPRINT SURVEY UNIT 3 A. SURVEY UNIT DESCRIPTION FB-0500 is the survey area located in the footprint of the former Turbine Building shown on site map FB 0500-03 SITE (Attachment 1). The north east corner of the Turbine Building is located at 407685N and 624185E using the Maine State Coordinate System (West Zone)
NAD 1927. Survey Unit 3 consisted of sub-slab soil and concrete footing remnants on the Turbine Building's west side. The total area was approximately 1730 M2 . While the survey area was located inside the Industrial Area of the site, it was outside of the plant's radiologically restricted area (RA).
B. SURVEY UNIT DESIGN INFORMATION The Turbine Building was typically maintained as a clean structure during plant operation.
However, radioactive material was present in systems and low levels of contamination were found in building sumps and drains. The area around the PCC/SCC pumps was considered to be a Class I area so the sub-slab soil within FB-0500 Survey Unit 3 was designated a Class 2 survey unit per the LTP (Table 5-1 B).
During the removal of a service water discharge pipe in this survey unit, soil contamination was found in excess of the DCGL. The area of elevated activity was bounded to 25 m2 by soil scans and samples. A 50 m2 area was reclassified to Class 1, removed from the scope of Survey Unit 3, and was designated Survey Unit 4.
The survey unit design parameters are summarized in Table 1. Given a relative shift of 3.0, it was determined that 14 direct soil sample points were required for the Sign Test. The soil measurement locations were generated using a random start, fixed grid and are shown on map FB 0500-03b (Attachment 1). Soil measurements consisted of soil samples that were analyzed with laboratory gamma spectroscopy instrumentation.
A 10-100% scan coverage of the area was rejuired.1 Approximately 50% scan coverage was obtained by scanning 36 locations each 25 m (totaling 900 in2 ). The location of the scan areas are shown on map FB 0500-03a (Attachment 1).
The survey instruments used, their MDC values, and alarm setpoints are provided in Attachment 2.
Background values were established for the scan measurements, based on local scaler values in the survey unit. These background values were used to establish scan alarm setpoints.
LTP Table 5-3 FB-0500-03, Revision 0 Page 2 of 20
TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 1730 mz Class 2 Based on an adjusted LBGR of Number of Direct 14 3.69 pCi/g, sigma 2 of 0.17 pCi/g Measurements Required and a relative shift of 3.0.
Type I = Type II = 0.05 Sample Area 123.57 m} 1730 m' / 14 Sample Grid Spacing 11.1 mx 11.1 m Class 2 Area Scan Grid Area 5 m x 5 rn Class 2 Area Area Factor N/A Class 2 Area Scan Survey Area 900 mL Class 2 Area - 50%
Background '
SPA-3Average background + DI 6-150, EC-009-01, SP-Iscn 000 c/rn LTP Section 5 Scan Investigation Level 3 sigma of background EC-009-01 (Reference 1)
See Table 2-2 _______________
DCGL DCGL4.2 ~i/gLTP 4.2 pCi/g Revision (Reference 2) 3 Design DCGLEMC N/A Class 2 Area C. SURVEY RESULTS As required, 14 direct soil measurements were made. Direct measurement data are presented in Table 2. All direct measurements were below the DCGL.
Of the 36 grids scanned, 8 grids had verified alarms. One additional grid (S030) was investigated after receiving a false positive indication. The investigation results are discussed in Section D.
2 LTP Table 5-IC, footnote a, R0200 yard east FB-0500-03, Revision 0 Page 3 of 20
TABLE 2 SOIL SAMPLE RESULTS Soil Sample ID l C137 (Ci/g) Uncertainty l Co-60 l Uncertainty Application Number pCi/g (pCi/g) pCi/g of Unity Rule FBO500-03-2-SOOISS <3.08E-02 NA < 3.31E-02 NA 2.94E-02 FB0500-03-2-SO02SS <2.96E-02 NA < 3.1 1E-02 NA 2.78E-02 FBO500-03-2-SO03SS <3.01E-02 NA < 3.52E-02 NA 3.06E-02 FBO500-03-2-SO04SS <3.031E-02 NA < 3.39E-02 NA 2.98E-02 FBO500-03-2-SOO5SS <3.17E-02 NA < 3.1OE-02 NA 2.82E-02 FBO500-03-2-SO06SS <2.1OE-02 NA < 2.84E-02 NA 2.39E-02 FBO500-03-2-SO07SS <3.16E-02 NA <3.188E-02 NA 2.87E-02 FBO500-03-2-SO08SS <2.73E-02 NA < 3.09E-02 NA 2.71E-02 FBO500-03-2-SO09SS 6.88E-02 1.94E-02 2.82E-01 2.46E-02 2.04E-0I FBO500-03-2-SOIOSS <2.75E-02 NA < 2.89E-02 NA 2.58E-02 FB0500-03-2-SOI ISS <2.84E-02 NA <3.00E-02 NA 2.67E-02 FBO500-03-2-SO12SS <2.76E-02 NA <2.86E-02 NA 2.56E-02 FBO500-03-2-SO13SS <2.94E-02 NA <3.18E-02 NA 2.82E-02 FBO500-03-2-SO14SS 3.56E-02 1.56E-02 <2.07E-02 NA 2.23E-02 Sample Mean 3.2 1E-02 4.84E-02 3.99E-02 Sample Median 2.99E-02 3.1 lE-02 2.80E-02 Standard Deviation 1.lOE-02 6.73E-02 4.73E-02 Range 0.021 - 0.069 0.021 - 0.282 0.022 - 0.204 NOTES
- 1. The Co-60 DCGL of 1.5 pCi/g is an "adjusted DCGL" and can be derived from the unitized dose for surface soil, LTP Table 6-7. The resulting DCGL for Co-60 alone is I pCi/g x 10/6.58 mrem/y or 1.5 pCi/g. This relationship is not impacted by the updated dose model in the activated concrete related license amendment (References 3 and 4).
- 2. "<" indicates MDC value.
D. SURVEY UNIT INVESTIGATIONS PERFORMED AND THEIR RESULTS The nine investigations consisted of re-scanning the grid and taking a soil sample at the highest count-rate location. The soil samples were analyzed by gamma spectroscopy. All soil sample results were at the MDC except a concentration of 0.986 pCi/g of Co-60 was detected in one sample (S033). This sample did not exceed the DCGL of 1.5 pCi/g for Co-
- 60. The results of the investigation measurements are tabulated in Attachment 3 (Table 3-1).
FB-0500-03, Revision 0 Page 4 of 20
E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including mean, median, standard deviation, and sample result range, are provided in Table 2. The mean and median activities were less than the DCGL for both Co-60 and Cs-137. The soil sampling results yielded a positive indication of plant-derived nuclides in two direct samples and one investigated grid.
The highest reported value for Cesium-137 was 1.6 % of the DCGL (4.2 pCi/g), and the highest reported value for Co-60 was 65.7% of the DCGL (1.5 pCi/g). The combined concentrations of Cs-137 and Co-60 do not exceed the unity rule value of 1. A trace amount (0.15 pCi/g) of Sb-125 was detected in soil sample S009. This is consistent with contamination from the service water pipe where high Co-60 activity is sometimes accompanied by lower levels of Sb-125. Compared to the NUREG-1727 soil value, the Sb-125 activity would equal a unitized value of 0.015.
For illustrative purposes, as indicated in LTP Section 5.9.3, a simplified general retrospective dose estimate can be calculated from the average residual contamination level. Cs-137 activity results in a non-positive value of activity once the established mean fallout Cs-137 background value (0.19 pCi/g) is subtracted from the survey unit mean (0.03 pCi/g), and does not contribute to the annual dose rate. However, the mean value of 0.048 pCi/g of Co-60 equates to a dose rate of 0.32 mrem/year 3 . However, for the purposes of demonstrating compliance with the radiological criteria for license termination and the enhanced State Criteria, background Cs-137 activity is not subtracted from the soil sample analysis activity values.
F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with this Survey Unit, including relevant statistical information. Based on survey unit direct measurement data, this attachment provides the Sign Test Summary, Quantile Plot, Histogram, and Retrospective Power Curve.
I. The Sign Test Summary provides an overall summary of design input and resulting calculated values used to determine the required number (N) of direct measurements (per LTP Section 5.4.2). The Sign Test Summary is a separate statistical analysis that also calculates the mean, median, and standard deviation of the direct measurements.
The critical value and the result of the Sign Test are provided in the Sign Test Summary table, as well as a listing of the key release criteria. As is shown in the table, all of the key release criteria, except that the design sigma was less than actual unitized sigma, were clearly satisfied for the FSS of this survey unit. Refer to Section G for a discussion on the sigma values.
3 (0.048 pCi/g/1.5 pCi/g) x 10 mren/year = 0.32 mrem/year FB-0500-03, Revision 0 Page 5 of 20
- 2. The Quantile Plot was generated from direct measurement data listed in Table 2. The data set and plot are consistent with expectations for a Class 2 survey unit. All of the measurements are well below the DCGL of 4.2 pCi/g.
- 3. A Histogram Plot was also developed based on the direct measurement values. This plot shows that the direct data were essentially a log-normal distribution due to the presence of one outlier.
- 4. A Retrospective Power Curve was constructed, based on FSS results. The curve shows that this survey unit having a mean residual activity at a small fraction of the DCGL has a high probability ("power") of meeting the release criteria. Thus, it can be concluded that the direct measurement data support rejection of the null hypothesis, providing high confidence that the survey unit satisfied the release criteria and that the data quality objectives were met.
G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class 2 area; the FSS results were consistent with that classification. The direct measurement sample unitized standard deviation exceeded the design sigma. However, the increase in sigma would not have affected the relative shift.
Therefore, the survey design had sufficient power to reject the null hypothesis so no additional measurements were required.
H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 3 was designed and performed using the criteria of the approved LTP Revision 3 Addenda (Reference 2). The only subsequent LTP changes were provided in the proposed license amendment related to modifications of the activated concrete remediation plan submitted September 11, 2003 (References 3 and 4). Changes represented in this later proposed license amendment have been evaluated and have no impact on the design, conduct, or assessment on the final status survey on Survey Unit 3.
I. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class 2 area.
The survey design parameters are presented in Table 1. The required number of direct measurements was determined for the Sign Test in accordance with the LTP. As presented in Table 2, all direct measurements were less than the DCGL. The presence of Sb-125 was detected at a low level. Even though Sb-125 is not a typical soil nuclide, its unitized activity was evaluated and found to still meet the unity rule.
A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied. The direct measurement sigma was determined to be greater than that used for design, however, a sufficient number of samples was taken.
FB-0500-03, Revision 0 Page 6 of 20
The Retrospective Power Curve shown in Attachment 4 confirmed that sufficient samples were taken to support rejection of the null hypothesis, providing high confidence that the survey unit satisfied the release criteria and the data quality objectives were met. Attachment 4 also revealed that direct measurement data represented essentially a log-normal distribution, due to the presence of one outlier.
The scan survey design for this survey unit was developed in accordance with the LTP with significant aspects of the design discussed in Section B and Table 1. Scanning resulted in eight verified alarms and one additional grid investigated. Investigations were conducted and no soil concentrations exceeded the DCGL.
It is concluded that FB-0500 Survey Unit 3 meets the release criteria of I0CFR20.1402 and the State of Maine enhanced criteria.
J. REFERENCES
- 1. Maine Yankee Engineering Calculation, EC 009-01
- 2. Maine Yankee License Termination Plan, Revision 3, October 15, 2002 and Addenda, provided by Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002
- 3. MY letter to the NRC, MN-03-049, dated September 11, 2003, "Proposed Change:
Revised Activated Concrete DCGL and More Realistic Activated Concrete Dose Modeling"
- 4. NRC Letter to Maine Yankee dated February 18, 2004, Approval of Activated Concrete Amendment
- 5. Maine Yankee Procedure PMP 6.7.8, Attachment E FB-0500-03, Revision 0 Page 7 of 20
Attachment 1 Survey Unit Maps FB-0500-03, Revision 0 Page 8 of 20
Maine Yankee Maine Yankee Decommissioning ProjectSurvey Fo Map ID #:FB 0500-03 SITE Decommissioning Team Tmv eOu r c I Revised: 121-O3 Survey Type: El Characterization El Turnover U Final Status Survey ISurvey Area Name: Turbine Building Phase 11 406.500 N 0
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Maine Yankee Map ID#: FB 0500-03a Decommissioning Team IMaine Yankee DecommissioningProjectSurvey Form IRevised: 12-9-03 Survey Type: ] Characterization El Turnover C Final Status Survey Survey Area Name: Turbine Building Phase II S033
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Maine Yankee Map IL) #: FB 0500-03b Decommissioning Team Maine Yankee DecommissioningProjectSurvey Foron Revised: 12-903 Survey Type: O Characterization O Turnover 1 Final Status Survey I Survey Area Name: Turbine Building Phase II NJ C-CY, CP 3 3 _
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Attachment 2 Survey Unit Instrumcntation FB-0500-03, Revision 0 Page 12 of 20
TABLE 2-1 INSTRUMENTATION INFORMATION E-600 S/N I Probe SIN (type) 1933 1 725332 (SPA-3)
_ 2620 l 726560 (SPA-3)
IIPGe Detectors for Lab Analysis of Volumetric Samples I Detector Number MDC (pCi/g) j FSS-I I 0.02- 0.11 FSS-2 0.02 - 0.11 DET2 < 0.15 DET3 < 0.15 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESITGATION LEVEL Detector SPA-3 Comments DCGL for land areas outside DCGL 4.2 Cs-137 the Restricted Area applied (pCi/g) 1.5 Co-60 (LTP Revision 3 Addenda, Reference 2)
LTP Table 5-6, Design Scan Scan MDC 5.9 MDC (LTP Revision 3 (pCi/g) Addenda, Reference 2)
Investigation Level 3.0 sigma of Background -
(Alarm Setpoint) 12,860 EC-009-01 (Reference 1)
. (cpm)
FB-0500-03, Revision 0 Page 13 of 20
Attachment 3 Investigation Table FB-0500-03, Revision 0 Page 14 of 20
TABLE 3-1 INVESTIGATION TABLE XBO500 SU#3 INVESTIGATED GRIDS Original Survey Results Investigation Results Investigated Investigation Alarm Scan Investigation Scan Co-60 Cs-137 Unity Grids Reason Setpoint Value Measurement Sample ID # = (pCi/g) _ (pCi/g) DCGL
_ (cpm) (cpm) (cpm) _ = _=
Soo I ALARM 12,860 13,700 15,200 XBO500-03-2-S001-RSOOO < 1.24E-01 < 9.34E-02 0.10 S004 ALARM 12,860 14,980 12,090 XBO500-03-2-S004-SS000 < 3.38E-02 < 3.22E-02 0.03 S018 ALARM 12,860 13,150 13,440 XBO500-03-2-S018-RS000 < 1.24E-01 < 1.14E-01 0.11 S026 ALARM 12,860 13,630 13,410 XBO500-03-2-S026-SS000 < 3.66E-02 < 3.67E-02 0.03 S029 ALARM 12,860 13,620 13,670 XBO500-03-2-S029-SS000 < 3.23E-02 < 2.94E-02 0.03 S030 Professional 12,860 12,310 12,390 XB0500-03-2-S030-SS000 < 3.40E-02 < 3.05E-02 0.03 Judgement = _
S033 ALARM 12,860 13,860 12,760 XBO500-03-2-S033-SS000 = 9.86E-01 < 4.251E-02 0.67 S035 ALARM 12,860 14,000 13,470 XBO500-03-2-S035-SSOOO < 3.37E-02 < 3.17E-02 0.03 S036 ALARM 12,860 14,760 13,470 XBO500-03-2-S036-SS000 < 3.09E-02 < 3.02E-02 0.03
"<" indicates MDA value _ _
FB-0500-03, Revision 0 Page 15 of 20
Attachment 4 Statistical Data FB-0500-03, Revision 0 Page 16 of 20
Survey Package FB-0500 Unit 3 UNITY Soil Sign Test Summary
>zr'-ti'-'lsEva nuat o~n~rnPUali ornmets~t-' 'id;Z.,.t-t-m-'j$
tw Survey Package: FB-0500 Turbine Bld Footprint Survey Unit: 03 Evaluator: GP __________________
DCGLW: 4.20E+00 DCGLemc: N/A LBGR: 3.69E+00 Sigma: 4.00E-02 Unitized Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A tcalm~~a culatdVle ii'-.6'4.as,.,j54 ' !'-gCdrfiffint5sa'-ih Za: ; ,1.645 1.645 Sign p: 0.99865 Calculated Relative Shift: 12.7 Relative Shift Used: 3.0 Uses 3.0 if Relative Shift is >3 N-Value: 11 N-Value+20%:
- 14
'I Cittamihpo Data V Ornmdh,-Xt~omm'tw;F{. g-Number of Samples: , - 14 Median: . 2.80E-02 Mean: 3.99E-02 Net Sample Standard Deviation: ; 4.73E-02 Total Standard Deviation: <:.. 4.73E-02 SRSS Maximum: ..- 2.04E-01 J.
N -ad .(>.'.'gn.stRfuti .o-*, 't-S i i-.i* m l2 t t:t Adjusted N Value: - - 14 S+ Value:j: 14 Critical Value: j < 10 Sign test results: j Pass' Sufficient samples collected: K-'- Pass Maximum value <DCGL ,,: ' Pass Median value <DCGL:,: Pass Mean value <DCGLw -, Pass Maximum value <DCGLemc: C Pass Total Standard Deviation <=Sigma: iz'j' nvestigaie See Section G of the Release Record Criteria comparison results: Alnvestigate See Section G of the Release Record alls->5 I Du_ b~2 _ _____ .__Tr______i_ ____o_____
The survey unit passes all conditions:l 4 M.-,:;elhvestigate The Survey Unit passes FB-0500-SU3-SoiISign-UN1TY 11/8/04 423 PM FB-0500-03, Revision 0 Page 17 of 20
FB-0500 SU-3 Quantile Plot 0.250 IT 0.200 -4 a)
N
._ 0.150 -4 oQ o0 V C
C
- Activity (unitized) 4-
"00
- Median (unitized)
N) <
0
.: 0.100 -1 C
0.050
___ . V. _ . I ,. -
0.000 0 25 50 75 100 Percent
One-Sample T-Test Report Page/Date/Time 2 11/9/04 4:49:38 AM Database C:\Program Files\NCSS97\FBO500SU3.SO Variable C2 Plots Section Histogram of FB-0500, SU-3 25.000
_C 18.750 00 E
O 12.500 D
z 6.250 n n 0.000 0.063 0.125 ' '0.186 0.250 Activity (unitied)
FB-0500-03, Revision 0 Page 19 of 20
One-Sample T-Test Power Analysis Page/Date/Time 2 11/9/04 4:50:51 AM Chart Section Retrospective Power Curve
- I,
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ai) 0.6 -
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0.2-0.0 0.0 0.2 0.4 0.6 Survey Unit Mean (unitized)
FB-0500-03, Revision 0 Page 20 of 20