ML043290292
| ML043290292 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/17/2004 |
| From: | Pillsbury G Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FB-0500-01, Rev 0 | |
| Download: ML043290292 (22) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-0500 TURBINE BUILDING FOOTPRINT SURVEY UNIT I
-sDat-Prepared By: _SHi Uj~S Epin 7 ig/nature Printed Name/
Reviewed By: itr 1c lIT 9-pecizfliture g-o~Zgz< 1oizef Printed Name Date:
Reviewed By: 1 le
/e As q & /0 - Zz -°4g Independent Reviewer -
Signature Approved By: 4/Date:- e St pcrintenden ignature Printed Name /
Date:
Approved By: FZ,7A /
AKS, MOP - Signature Printed Name
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-0500 TURBINE BUILDING FOOTPRINT SURVEY UNIT I A. SURVEY UNIT DESCRIPTION FB-0500 Survey Unit 1, the Turbine Building Footprint, consists of the soil footprint of the east and south sections of the former Turbine Building (that portion of the slab which contained the extension of the rail spur into the backyard - see map FBO500-01, Attachment 1). The total survey area comprises approximately 2766 m2 of sub-slab soil and concrete remnants. While the survey area was located inside the Industrial Area of the site, it was outside of the plant's radiologically restricted area (RA) at Maine State Grid Coordinates 624000 E and 407500 N.
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 lowv 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 I was designated a Class 2 survey unit per the LTP (Table 5- 1B).
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 square grid and are shown on map FBO500-02, (Attachment 1). Direct measurements consisted of soil samples that were analyzed with laboratory gamma spectroscopy instrumentation.
A 10-100% scan coverage of the area was required'. Approximately 38% scan coverage of the sub-slab area was used. Scan grids were typically 25 m2 areas as indicated on the attached survey map (FBO500-03, Attachment 1). Scans were biased to soil areas due to a higher potential for containing residual contamination.
Once the floor slab was removed, several equipment foundation remnants were left as shown on map FBO500-03 by the shaded areas. Structure demolition left the concrete remnants with surfaces too rough to survey as a separate unit. Volumetric concrete samples (15) were taken to augment the soil FSS using a random start, square grid as shown on map FB0500-04.
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.
See additional discussion in Section D.
LTP Table 5-3 FB-0500-01, Revision 0 Page 2 of 22
TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria J Basis Area 2 2158 m2 Table 5-2 of the LTP - Class 2 Based on an adjusted LBGR of Number of Direct 14 3.69 pCi/g, sigma 3 of 0.17 pCi/g Measurements Required and relative shift of 3.0.
Type 1 = Type II = 0.05 Sample Area 154 m2 Class 2 Area Sample Grid Spacing 12.4 m x 12.4 m Class 2 Area Scan Grid Area 5 m x 5 m (except grid 42 Class 2 Area at 2.5 m x Oim)
Area Factor N/A Class 2 Area Scan Survey Area 1050 m2 Class 2 Area: 10-100%
Background *- -l J ';' '2 ';i '
SPA-3Average background DI 6-150, EC-009-01, scn IP-000 c/rn LTP Section 5 Scan Investigation Level 3 sigma of background + EC 009-01 (Reference 1)
DCGL. See Table 2-2 DCGL 4.2 pCi/g LTP Revision 2 (Reference 2)
Design DCGLENIC N/A Class 2 Area C. SURVEY UNIT RESULTS Seventeen direct soil samples were obtained in Survey Unit I (conservatively greater than the 14 required). All direct measurements were below the DCGL. The resulting soil sample measurement data are presented in Table 2.
Seventeen alarms were received during scanning which required investigation as discussed in Section D.
In addition, 15 volumetric concrete samples were collected from the foundation remnants and analyzed with no plant-derived activity detected at an MDC of 0.15 pCi/g.
2 The survey design only considered the sub-slab soil area. This results in a conservative sample area and sample grid spacing.
3 LTP Table 5-IC, footnote a, sigma for R200 yard east FB-0500-01, Revision 0 Page 3 of 22
TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCi/g)
FB-0500-1-S001 <0.051 FB-0500-1-S002 <0.050 FB-0500-1-S003 <0.049 FB-0500-1-S004 <0.052 FB-0500-1-S005 <0.050 FB-0500-1-S006 <0.052 FB-0500-1-S007 <0.051 FB-0500-1-S008 <0.049 FB-0500-1-S009 <0.050 FB-0500-1-SOIO <0.047 FB-0500-1-SOI 1 <0.047 FB-0500-1-S012 <0.047 FB-0500-1-S013 <0.052 FB-0500-1-S014 <0.052 FB-0500-1-S015 <0.055 FB-0500-1-S016 <0.050 FB-0500-1-S017 <0.050 Mean 0.050 Median 0.050 Standard Deviation 0.002 Range 0.047 - 0.055 NOTES
- 2. "<" indicates MDC value.
D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS Each grid exhibiting an alarm was re-scanned to determine the location of the highest count rate. At the highest count rate location a one-minute scaler count, GR-130 gamma spectroscopy (used for information only) measurement and a soil sample were taken to determine whether the alarm was caused by plant-derived radioactive material. The investigations showed no evidence of plant-derived radioactive material (Table 3-1, Attachment 3).
FB-0500-01, Revision 0 Page 4 of 22
During the time of the FB-0500 survey, the scan methodology changed as a result of detailed investigation into the data processing mechanism of the E-600 data logger. Key program changes resulting from the E600 investigation were the elimination of the DCGL term and the use of local scaler background measurements in establishing the investigation level.
As a result of the above-mentioned work with the E600 instrument, a review of Survey Unit I background and scan data was conducted. A revised alarm setpoint (14,800 cpm) was calculated based on the latest scan methodology. This review indicated that one additional scan grid (FBO500-1-S0035) may have alarned had the revised setpoint been used. No further investigation was considered warranted for the following reasons.
I. The scan grids for this Class 2 area are relatively small (25 m2).
- 2. Soil samples S004 and S005 were taken to the north and south of grid 35 with no evidence of plant derived nuclides.
- 3. Adjacent grids S034 and S028 did receive alarms and were investigated; no plant derived nuclides were detected.
- 4. All direct and investigation soil samples elsewhere in the survey unit indicated < MDA values (Table 3-1, Attachment 3).
Therefore, additional investigation of scan grid FBO500-1-S0035 would not likely reveal the presence of plant-derived activity above background.
E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample result range, are provided in Table 2. None of the samples had activity above the MDA. Both the mean and the median activities were less than the DCGL assuming activity was present at the MDA. The maximum soil result for Cs-I 37 was approximately 1.3 percent of the DCGL.
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 by subtracting the established mean fallout Cs-137 background value 4 (0.19 pCi/g) for disturbed soil from the survey unit sample mean activity (0.050 pCi/g). The result is a net value of -0.14 pCi/g.
This would equate to an annual dose rate of 0.0 mremly. However, for the purposes of demonstrating compliance with the radiological criteria for license termination and the enhanced State Criteria, background activity is not subtracted from the soil sample analysis activity values.
4 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 3)
FB-0500-01, Revision 0 Page S of 22
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 (Table I) 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 were clearly satisfied for the FSS of this survey unit.
- 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 normal distribution with no outliers.
- 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.
As mentioned in Section B, concrete volumetric samples were obtained from foundation remnants to demonstrate that demolition activities did not contaminate the concrete surfaces.
Laboratory gamma spectroscopy analysis on the samples determined that none of the concrete samples had plant-derived activity detected at an MDC of 0.15 pCi/g.
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 standard deviation was less than the design sigma. Thus, no additional measurements were required.
FB-0500-01, Revision 0 Page 6 of 22
}1. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed, performed and evaluated in late 2001. The design was performed to the criteria of the LTP, Revision 2 (Reference 2). As discussed and reviewed in Section D of this Release Record, scan methodology changes were made during this time frame, relating to the use of the E600 instrument.
LTP changes have been made subsequent to the completion of this survey. Those LTP changes with potential for impact to this survey unit are listed below.
- 1. Requirement to check background + 1000 cpm prior to the scan of each grid. (LTP 5.5.2.f; LTP Revision 3 Addenda, References 4, 5 and 6).
- 3. Change in alarm setpoint methodology during the evolution of the use of E600 (use of scaler vs. peak values to establish the investigation level and deletion of the DCGL term).
- 4. LTP changes in the activated concrete license amendment (References 7 and 8).
- 5. The procedural commitment to the State of Maine of limiting grid size to 10 m2 (Reference 9).
These LTP changes were evaluated and found to have no impact on the results or conclusions of the FSS of FB-0500 Survey Unit 1.
- 1. 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 of 4.2 pCi/g.
A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied. The direct measurement sigma was determined to be less than that used for design, thus indicating that a sufficient number of samples was taken.
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 normal distribution, with no outliers.
FB-0500-01, Revision 0 Page 7 of 22
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 17 verified alarms (Section D) for evaluation. Investigations showed no evidence of plant-derived radionuclides above background.
It is concluded that FB-0500, Survey Unit 1, met the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.
J. REFERENCES
- 1. Maine Yankee Engineering Calculation, EC 009-01
- 3. Approach for Dealing with Background Radioactivity for Maine Yankee Final Status Surveys, Attachment E to Maine Yankee Procedure, FSS Data Processing and Reporting, PMP 6.7.8
- 4. Maine Yankee License Termination Plan, Revision 3, Maine Yankee letter to the NRC, MN-02-048, dated October 15, 2002
- 5. Maine Yankee License Termination Plan, Revision 3 Addenda, Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002
- 7. 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"
- 8. NRC Letter to Maine Yankee dated February 18, 2004, Approval of Activated Concrete Amendment
- 9. MY Letter to the NRC, MN-03-009, February 26, 2003 FB-0500-01, Revision 0 Page 8 of 22
Attachment 1 Survey Unit Maps FB-0500-01, Revision 0 Page 9 of 22
Maine Yankee l l Map ID #:
Decommissioning Team MAinF5e Y0a0ee Deco issioning ProjectSurvey For l O0O1 Survey Type: - Characterization - Turnover U Final Status Survey ISurvey Area Name: Turbine/Service Building Slab 623.000 E 623,500 E 624,000 E 624,500 E 625,000 E SCALE I 1AKI i
0 400 800 1200 Zd N FB-0500-01, Revision 0 Page 10 of 22
Maine Yankee . . . Map ID#
Decommissioning Team aine Yankee DecoiiimissioningProject Siiii'e orm FBO500-02 Survey Type: C Characterization E Turnover
- Final Status Survey ISurvey Area Name: Turbine/Service Bldg Sub Slab Turbine/Service Building Sub Slab MN Unit 1 Soil Sample gS~ N Locations S017 (88,67)
.__1 IX X
-- 1-- -n I I 5011 5010 I II (63,30) (51,30 1 L i I , I I
Center of Column B 9 (S,W) - Sample Location as measured from Column B 9 South and West NOTE: Measurements are in meters. FB-0500-OI, Revision 0 Page 11 of 9
Maine Yankee I . , e .o . .i.sMap PD #:
Decommissioning Team Maie Yankee DecoImissioningProject Siiney Form FBO500-3 Survey Type: L Characterization L Turnover
- Final Status Survey ISurvey Area Name: TurbinelService Bldg Sub Slab Turbine/Service Building MN Sub Slab Z- r= N Unit 1 Soil Scan Locations 112 3/4 w
Column B 9 112 314 1 2 3 4 5 6 7 8 9 Note: Scan locations are 25 square meters.
m - Concrete FB-0500-01, Revision 0 Pn"e 1#7 of)')
Maine Yankee I Map ID #:
Decommissioning Team MAtaiie lantkee Decomtmiiissiontinzg Project Surviejy For) FBO500-04 Survey Type: L Characterization L Turnover
- Final Status Survey Survey Area Name: Turbine/Service Bldg Sub Slab Turbine/Service Building Sub Slab Concrete MN Survey Unit 1 D- N Sample Locations C014 '
(76,56) c009 Co1o (58,27)
Co13 Li69.29) oi C006 (23,9)
I (0,0)
Center of Column B 9 (S,W) - Sample Location as measured from Column B 9 South and West NOTE: Measurements are in meters.
FB-0500-0i, Revision 0
Attachment 2 Survey Unit Instrumentation FB-0500-OI, Revision 0 Page 14 of 22
TABLE 2-1 INSTRUMENT INFORMATION E-600 S/N Probe S/N (type) 1606 725332 (SPA-3) 1606 725328 (SPA-3) 1606 726554 (SPA-3) 1606 726560 (SPA-3) 1625 726554 (SPA-3) 1625 726560 (SPA-3) 1647 725328 (SPA-3) 1631 726560 (SPA-3)
IIPGe Detectors for Lab Analysis of Volumetric Samples I Detector Number I MDC (pCi/g) I FSS-1 0.05 to 0.11 FSS-2 0.05 to 0.11 DET 2 0.15 DET3 0.15 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESTIGATION LEVEL Detector l SPA-3 Comments II MLTP Table 5-6, Design Scan MDC Scan MDC 5.9 (LTP Revision 3 Addenda, L(pCi/g) Reference 5)
DCGL DCGL for land areas outside the DCCL 4.2 Restricted Area applied (LTP (pCi/g) Revision 3 Addenda, Reference 5)
Investigation Level 3.0 sigma of background + DCGL (Alarm Setpoint) 14,900 EC-009-01 (Reference 1) cPmr_________n________________
FB-0500-01, Revision 0 Page 15 of 22
Attachment 3 Investigation Table FB-0500-01, Revision 0 Page 16 of 22
TABLE 3-1 INVESTIGATION RESULTS Original Scan Results Investigation Results Investigation Scan Alarm Investigation Maximum Investigation Result Location Location J Value (m)Number(c (cPm) nv er Scan Value (cPm)
)(plg Cs-137 (pCi/g) 28 15700 XB-0500-1-S001 14200 < 0.047 32 32500 XB-0500-1-S002 12800 < 0.043 33 23300 XB-0500-1-S003 12700 < 0.054 34 17100 XB-0500-1-S004 18900 <0.046 48 14900 XB-0500-1-S005 13500 < 0.053 49 15000 XB-0500-1-S006 13600 < 0.047 50 15400 XB-0500-1-S007 13400 < 0.040 51 15700 XB-0500-1-S008 13800 < 0.043 52 15000 XB-0500-1-S009 13500 < 0.040 53 15400 XB-0500-1-SOIO 14800 < 0.046 54 16000 XB-0500-1-S011 14500 < 0.046 55 15000 XB-0500-1-S012 14200 < 0.050 56 15400 XB-0500-1-S013 13800 < 0.047 57 15900 XB-0500-1-S014 15400 < 0.054 58 16100 XB-0500-1-S015 14600 < 0.048 59 15900 XB-0500-1-S016 13500 < 0.046 60 16600 XB-0500-1-S017 19100 < 0.045 NOTE: All samples were evaluated to be < MDC for Co-60 (i.e., < 0.1 pCi/g)
FB-0500-01, Revision 0 Page 17 of 22
Attachment 4 Statistical Data FB-0500-01, Revision 0 Page 18 of 22
Survey Package FBO500 Unit I Soil Sign Test Summary
-Evaluatlon InputVa ues i-z:§ 3 , 2*-'., Comments' i Survey Package: FBO500 Turbine Building Sub-Slab Soil Survey Unit: 01 Evaluator: GP DCGL,: 4.20E+OO DCGL,,,: 4.20E+O0 LBGR: 2.1 OE+00 Sigma: 1.70E-01 Type I error: K.':. 0.05 Type II error: 0.05 Nuclide: CS-1 37 Soil Type: NIA
':' uws idzJ:--idV:&'~~AtleC t--; ._.A"-fornmie-ns
.12645
.1.645 Sign p: Jr 0.99865 Calculated Relative Shift: 12.3 Relative Shift Used: ,3.0 Uses 3.0 if Relative Shift is >3 N-Value: .' 1 N-Value+20%: - - 14
- fId;.b. Datag ,aanlURe's ; rf , -',' -.-;' ;Com~onff.i Number of Samples: :17 Median: i.-.-5.00E-02 Mean: - s-4 5.02E-02 _
Net Sample Standard Deviation: Ci'2.1 1 E-03 Total Standard Deviation: 2.1 E-03 SRSS Maximum:. J C(5.50E-02
$, ,,i< Aih Ijn,-Test Roslts -. R,;,,
Adjusted N Value: ' 17 S+ Value: ;.<17_________ _______
Critical Value: 12 Sign test results: .. Pass Sufficient samples collected: < ,' Pass Maximum value <DCGL.,: ; Pass Median value <DCGL,,: .' Pass Mean value <DCGL-: '.Pass Maximum value <DCGLe,: -Pass Total Standard Deviation <=Sigma: - a Criteria comparison results: ' 'Pass
,,~~ie?_
FBOSOO-SU1-SoilSign 11/2104 12:27 PM FB-0500-0I, Revision 0 Page 19 of 22
FBO500 SU-1 Quantile Plot 0.056 0.055 0.054 0.053
~ v 0 0.052 00 c
- Activity (pCi/g) s"0 'V %._O 0.051 co CC .4 6 64
- Median (pCi/g) 0.05 4: 0.049 0.048 0.047 -F 0.046 0 25 50 75 100 Percent
One-Sample T-Test Report Page/Date/Time 2 11/2/04 12:28:35 PM Database C:\Program Files\NCSS97\FBO500SU-1.S0 Variable C2 Plots Section Histogram of FB-0500, SU-1 C.)
E C')
.0 E
z Activity (pCVg)
FB-0500-01, Revision 0 Page 21 of 22
One-Sample T-Test Power Analysis Page/Date/Time 2 11/2/04 12:29:49 PM Chart Section Retrospective Power Curve 1.0- 0----
0.8 --- - _
(j 0.6 --- - -- -
0.4 --- --- -
I I I It I I I I I
, I I \
I I I I I Survey Unit Mean (pCi/g)
FB-0500-01, Revision 0 Page 22 of 22