ML043290362
| ML043290362 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/17/2004 |
| From: | Vanags U Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FR-0910-01, Rev 0 | |
| Download: ML043290362 (21) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0910 FIRE POND FOOTPRINT SURVEY UNIT I Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0910 FIRE POND FOOTPRINT SURVEY UNIT 1 A. SURVEY UNIT DESCRIPTION FRO91 0 Survey Area includes the Fire Pond footprint and the adjacent Fire Pond Pump House concrete slab, located about 700 feet northwest of the plant (Maine State Grid Coordinates 623500 E and 408250 N) as shown on map FR-0910-01 (Attachment 1). Water for firefighting was stored in a man-made water storage pond, constructed of concrete and gravel, and rubber-lined. The pond was 278 feet long, 200 feet wide and 15 feet deep, with a capacity of approximately 3.4 million gallons. Makeup water for the pond was supplied from the offsite Montsweag Reservoir, located near the junction of U.S. Route I and Route 144.
Water was drawn from the water storage pond by two fire pumps located in the Fire Pump House. Survey Unit I consists of the Fire Pond footprint with a surface area of 9979 in2 ;
Survey Unit 2 consists of the Pump House Slab (I 19.3 M2 ). The survey unit was located outside of the plant's radiologically restricted area (RA) and industrial area.
B. SURVEY UNIT DESIGN INFORMATION Survey Unit I consists of the Fire Pond footprint and was designated a Class 3 survey unit' in accordance with the LTP (Table 5-IC).
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 randomly generated and are shown on map FR-09 10-02 (Attachment 1). Soil samples were analyzed with laboratory gamma spectroscopy instrumentation.
A 1% to 10% scan coverage of the area was required. 2 Scan grids (125 total3) were typically 8 m2 as shown on map FR-0910-03 (Attachment 1). The total scan area was approximately 10 00 m 2 , thus meeting the upper scan coverage requirement of 10%.
The survey instruments used, their MDC value, and alarm setpoints, are provided in Attachment 2.
Background values were established for the scan measurements. These background values were used to establish scan alarm setpoints. See additional discussion in Section D.
I The sediment layer at the bottom of the Fire Pond was found to have an average of about I pCVgram of Cs-) 37.
The Cs-137 in the sediment was determined to be the result of non-plant derived Cs-137 present in the environment that concentrated in organic material (EC-049-0 I).
2 LTP Table 5-3 3 The locations of the scanning grids were biased primarily to areas of the Fire Pond that were undisturbed, and were reasonably smooth to accommodate scanning with the SPA3 detector.
FR-0910-01, Revision 0 Page 2 of 21
TABLE I SURVEY UNIT DESIGN PARAMETERS
[ Survey Unit Design Criteria Basis Area 9979 m2 No limit for Class 3 Area Based on adjusted LBGR Number of Direct of 2.76 pCi/g, sigma4 of Measurements Required 14 0.48 pCi/g, and a relative shift of 3.0.
SType I = Type 11 = 0.05 lSample Area N/AClass 3 Area Sample Grid Spacing N/A Class 3 Area Scan Grid Area 125 grids sized 2 m x 4 m Class 3 Area Area Factor N/A Class 3 Area Scan Survey Area 1000 mi Class 3 Area: 1% - 10%
Background . ..-- ;
SPA-3 scan)DI 6-150, EC-009-01, SPA-3 (scan) Average background + 1000 c/mr LTP Section 5 Scan Investigation Level
_____________See 3 sigma of background + DCGL(Reference Table 2-2EC090(Rfrne1 1)
DCGL 4.2 pCi/g (LRTePfereneio2)3 Design DCGLEMC N/A Class 3 Area C. SURVEY RESULTS Fourteen direct measurements were obtained in Survey Unit 1. The resulting soil sample measurement data are presented in Table 2. All direct measurements were below the DCGL.
Thirty-four grids had alarms and required investigation. In addition, one direct measurement (CO14) location was investigated due to Co-60 activity being identified in the sample. The results of the investigation are discussed in Section D.
4 LTP Table 5-IC FR-0910-01, Revision 0 Page 3 of 21
TABLE 2 DIRECT MEASURE1ENTS lSaml Number l Cs-137 (pCi/g) Co-60 Unitized Value of SIpeNme s-3 pig (pCilg) j Unity Rule j FRO910-01-3-SOOI < 7.14E-02 < 6.71 E-02 6.17E-02 FRO910-01-3-SO02 < 8.37E-02 < 7.61 E-02 7.07E-02 FRO910-01-3-SO03 <5.75E-02 < 5.69E-02 5.16E-02 FRO910-01-3-SO04 <5.45E-02 <5.52E-02 4.98E-02 FRO910-01-3-SO05 < 6.22E-02 < 6.57E-02 5.86E-02 FRO910-01-3-SO06 <5.OOE-02 <5.47E-02 4.84E-02 FRO910-01-3-SO07 <5.57E-02 <5.14E-02 4.75E-02 FRO910-01-3-SO08 < 5.26E-02 <5.40E-02 4.85E-02 FRO910-01-3-SO09 <5.1 1E-02 <5.37E-02 4.80E-02 FRO910-01-3-SOIO < 6.04E-02 < 6.20E-02 5.57E-02 FRO910-01-3-SOI I < 5.14E-02 < 5.4 1E-02 4.83E-02 FRO910-01-3-SO12 < 5.39E-02 < 5.34E-02 4.84E-02 FRO910-01-3-S013 <6.26 E-02 < 7.01E-02 6.16E-02 FRO910-01-3-SO14 2.51E-01 + 5.24E-02 3.07E-01 + 4.34E-02 2.64E-01 Mean 7.27E-02 7.72E-02 0.0688 Median 5.66E-02 5.61E-02 0.0507 Standard 5.21 E-02 6.66E-02 0.0566 D eviation l Range 5.00E-02 to 2.51E-01 5.14E-02 to 3.07E-01 4.75E-02 to 2.64E-_01J NOTE: "<" symbol denotes less than MDA value for isotope analyzed.
D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS Of the 125 gids scanned, 34 grids alarmed and were investigated. A soil sample was taken at the highest scan value in the grid. The soil samples wvere isotopically analyzed and the results are shown in Attachment 3. Co-60 was not detected in the soil samples, but Cs-137 was detected at the expected environmental levels that are wvell below the DCGL of 4.2 pCi/g. In addition, direct soil sample S014 showved low level Co-60 activity. This finding was investigated by taking an additional five biased soil samples from the area around SO 14. The results showed no evidence of Co-60 activity. Scans of the area were performed to identify the areas of highest activity for sampling.
During the time of the FR-091 0 survey, the scan methodology changed as a result of detailed investigation into the data processing mechanism of the E600 data logger. Key program changes resulting from the E600 investigation were setting the investigation level at 3 sigma of background (excluding the DCGL term) and the use of local scaler background measurements in establishing the investigation level.
FR-0910-01, Revision 0 Page 4 of 21
As a result of the above-mentioned work with the E600 instrument, a review of Survey Unit 1 background and scan data was conducted. A revised alarm setpoint (14,666 cpm) was calculated based on the latest scan methodology and the previously established background.
This review indicated that four additional scan grids (FR-0910-1-S0094, 0113, 0122, and 0123) may have alarmed had the revised setpoint been used. No further investigation was considered warranted for the following reasons.
- 1. The scan grids for this Class 3 area are relatively small (8 m2 ).
- 2. Adjacent or nearby grids did receive alarms and wvere investigated; no plant-derived nuclides were detected above expected background levels.
- 3. All investigation soil samples elsewhere in the survey unit indicated values well below the DCGL of 4.2 pCi/g (Table 3-1, Attachment 3).
Therefore, additional investigation of scan grids FR-0910-l-S0094, 0113, 0122, and 0123 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. All results were below the unitized DCGL with a maximum value of 0.264.
Of the 14 soil samples from random locations within the Fire Pond (shown in Table 2), one sample (FRO910-01-3-S014) was found to have both Co-60 and Cs-137 at detectable levels.
Five additional soil samples were collected at the location of the positive soil sample. None of the samples showed Co-60 and all five showed Cs-137 at levels of 0.23 to 0.28 pCi/g. It is believed that the Co-60 (which was confined to a very small area) was likely due to wind blowvn contamination from the nearby RA.
For illustrative purposes, as indicated in LTP Section 5.9.3, a simplified general retrospective dose estimate can be calculated by subtracting fallout Cs-137 (0.19 pCi/g) from the average residual Cs-137 contamination level (0.073 pCi/g). The net result is-0.12 pCi/g. The resulting annual dose from Cs-137 is 0.0 mrmem/y. The unity fraction for Co-60 (0.077) would result in an annual dose of 0.77 mrem/y (0.077 x 10 mrem/y). 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.
FR-0910-01, Revision 0 Page 5 of 21
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 wvere 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 3 survey unit. All of the measurements are well below the unitized DCGL.
- 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 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 3 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.
FR-0910-01, Revision 0 Page 6 of 21
HI. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed, performed and evaluated in late 2002. The design was performed to the criteria of the LTP, Revision 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 Revision 3 Addenda, References 4 and 5).
- 3. Change in alarm setpoint methodology during the evolution of the use of E600 (deletion of the DCGL term).
- 4. LTP changes in the activated concrete license amendment (References 6 and 7).
- 5. The procedural commitment to the State of Maine of limiting grid size to 10 m2 (Reference 8).
These LTP changes were evaluated and found to have no impact on the results or conclusions of the FSS of FR-0910 Survey Unit 1.
- 1. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class 3 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 unitized DCGL.
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 one outlier.
FR-0910-01, Revision 0 Page 7 of 21
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 34 verified alarms (Section D) for evaluation. Attachment 3 shows the results of investigations.
There were no indications of residual plant-derived activity at a significant fraction of the DCGL.
It is concluded that FR-0910, Survey Unit 1, met the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.
J. REFERENCES I. Maine Yankee Engineering Calculation, EC-009-01
- 2. Maine Yankee License Termination Plan, Revision 3, Maine Yankee letter to the NRC, MN-02-048, dated October 15, 2002
- 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 Addenda, Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002
- 6. 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"
- 7. NRC Letter to Maine Yankee dated February 18, 2004, Approval of Activated Concrete Amendment
- 8. MY Letter to the NRC, MN-03-009, February 26, 2003 FR-0910-01, Revision 0 Page 8 of 21
Attachment 1 Survey Unit Maps FR-0910-01, Revision 0 Page 9 of21
Maine Yankee Mailie 1'aYikee DecounuiissiouiiigProject Surv~ej Foro, Map m ib 0:
Decommissioning Team FR-0910-01 Survey Type: = Characterization = Turnover
- Final Status Survey I Survey Area Name: Fire Pond 623,000 E 623,500 E 624.000 E 624,500 E 625,000 E 0 -4. o0 0b
-tU, C) (0 0D 0,
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zD z 0 S 0D z
SCALE MN
+400 +-i--
0 800 I' I00 Z- E - N FR-0910-01, Revision 0 Page 10 of 21
Maine Yankee Map ID #:
Decommissioning Team AIaine Yaintkee DecoinntissioninhgProjectSrney For17)1 FR-0910.02 Survey Type: _ Characterization - Turnover
- Final Status Survey I Survey Area Name: FIRE POND Fire Pond FR 0910 Unit 01 Soil Sample Locations
- Sol01 IV-\)(25,01 )
S02 \-, S03 (33,07)'O(30,09) w M S06
.S04 ?
(34,15)/<>
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) (2. 3,2 S07 3g(72,32)Gu (38,33) ,
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S09 (35,0 S13 \
(16,49)(
(5118 S )Sb (56,58)0 (38,54)
S14 "
(17,85)/-
- Soil sample Location
- Soil Sample Location Coordinates In meters (W,S)
(X-X Starting At The Northeast Corner Of The Fire Pond Berm FR-0910-01, Revision 0 Page IIof 21
Maine Yankee Map ID#:
Decommissioning Team Ilaitte latikee DecoininissioiiiigProjectSuney Forii IFR 0910-03 Survey Type: = Characterization = Turnover
- Final Status Survey Survey Area Name: FIRE POND Fire Pond N FR 0910 Unit 1 A Soil Scan Areas tA FR-0910-01, Revision 0 Page 12 of 21
Attachment 2 Survey Unit Instrumentation FR-0910-01, Revision 0 Page 13 of 21
TABLE 2-1 INSTRUMENT INFORMATION I E-600 S/N Probe SIN (type) 1619 725328 (SPA-3) 1619 725329 (SPA-3) 1625 725332 (SPA-3) 1641 725329 (SPA-3) 1643 725328 (SPA-3) 1619 726560 (SPA-3) 1643 726560 (SPA-3) 1928 725332 (SPA-3)
HPGe Detectors for Lab Analysis of Volumetric Samples I Detector Number I MDC (pCi/g)
I ISS-1 - 0.02 to 0.11 I FSS-2 J 0.02 to 0.11 J TABLE 2-2 INSTRUMENT SCAN MIDC AND COMPARISION WITH DCGL AND INVESTIGATION LEVEL Detector l SPA-3 Comments Scan MDC LTP Table 5-6, Design Scan MDC (Pci/g) 5.9 (LTP Revision 3 Addenda, Reference 4)
DCGL 4.2 (Cs- 13 7 DCGL for land areas outside the DCGL 4.2 (s-I 37) Restricted Area applied (LTP (pCi/g) 1.5 (Co-60) Revision 3 Addenda, Reference 4)
Investigation Level 14,810 (Alarm Setpoint) 3.0 sigma of background + DCGL EC-009-01 (Reference 1) cpm________________________________
FR-0910-01, Revision 0 Page 14 of 21
Attachment 3 Investigation Table FR-0910-01, Revision 0 Page 15 of 21
TABLE 3-1 INVESTIGATION TABLE Original Survey Results Investigaton Results Alarm MaxCs17Cmaio Investigation Setpoint Max Scan Investigation Cs-137 Comparison Location (cpm) Value (cPm) Scan (cpm) (pCig) to D(CGL Grid S037 14,810 14,810 14490 <6.32E-02 < DCGL Grid S038 14,810 15,720 14400 <5.40E-02 < DCGL Grid S039 14,810 16,020 15180 < 6.08E-02 < DCGL Grid S040 14,810 16,040 15460 < 6.50E-02 < DCGL Grid S041 14,810 16,850 15910 <5.19E-02 < DCGL Grid S042 14,810 15,410 15640 <5.96E-02 < DCGL Grid S043 14,810 15,200 14680 <5.50E-02 < DCGL Grid S044 14,810 16,910 16150 <5.72E-02 < DCGL Grid S045 14,810 19,440 16110 2.55E-01 + 4.1OE-02 < DCGL Grid S047 14,810 14,900 15730 2.01E-01 + 3.60E-02 < DCGL Grid S048 14,810 16,530 14640 2.32E-01 + 3.78E-02 < DCGL Grid S049 14,810 15,180 14860 2.03E-01 + 3.30E-02 < DCGL Grid S050 14,810 16,350 15960 2.08E-01 + 3.59E-02 < DCGL Grid S051 14,810 17,700 14790 2.40E-01 + 3.74E-02 < DCGL Grid S053 14,810 14,860 14020 2.38E-01 + 3.86E-02 < DCGL Grid S060 14,810 15,020 13570 1.18E-01 + 2.77E-02 < DCGL Grid S067 14,810 15,260 13730 <4.92E-02 < DCGL Grid S068 14,810 17,400 14130 <6.89E-02 < DCGL Grid S069 14,810 22,400 14260 < 7.86E-02 < DCGL Grid S070 14,810 21,700 14220 < 8.27E-02 < DCGL Grid S071 14,810 22,200 13990 <7.57E-02 < DCGL Grid S072 14,810 22,700 14440 <5.90E-02 < DCGL Grid S073 14,810 22,000 15290 <8.40E-02 < DCGL Grid S074 14,810 23,700 14790 <5.IIE-02 < DCGL Grid S092 14,810 17,540 13320 2.93E-01 +4.1OE-02 < DCGL Grid S105 14,810 15,180 14550 <3.85E-02 < DCGL Grid S108 14,810 14,960 15570 2.66E-01 + 3.79E-02 <DCGL Grid Sl 14 14,810 15,000 16630 1.34E-01 + 3.18E-02 < DCGL Grid SI 15 14,810 15,000 15350 1.63E-01 + 3.20E-02 < DCGL Grid S1 16 14,810 15,900 16110 6.80E-02 + 2.65 E-02 < DCGL Grid S1 17 14,810 14,800 15380 2.28E-01 + 3.92E-02 < DCGL Grid SI 18 14,810 15,900 15420 9.22E-02 + 2.65E-02 < DCGL Grid SI 19 14,810 15,000 14090 2.26E-01 +3.81E-02 < DCGL Grid S124 14,810 14,810 16080 1.87E-01 + 3.44E-02 < DCGL FRO910-01 5 Soil Samples S014 N/A N/A 17,640 Average = 2.60E-02 < DCGL Soil Sample NOTES:
- 2. "<" indicates MDA.
FR-0910-01, Revision 0 Page 16 of 21
Attachment 4 Statistical Data FR-0910-01, Revision 0 Page 17 of 21
Survey Package FR-0910 Unit 1 UNITY Soil Sign Test Summary Survey Package: FR-0910 Forebay Survey Unit: 01 Evaluator: GP DCGL.: 1.OOE+00 Unitized DCGLem,: N/A LBGR: 5.OOE-01 Sigma: 1.14E-01 Type I error: - 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: NIA
,,Xb,~~~C s,,-Culae C;3 N-Value: , ' 11 N-Value+20%: .. - 144
-J ___>'. _
Number of Samples:. . 1 __
Median: . -: 5.OOE-02 Mean: , *;. 6.81E-02 Net Sample Standard Deviation: Am -5.63E-02 Total Standard Deviation: 5.63E-02 SRSS Maximum - 2.62E-01
- ~ ... ;
Adjusted N Value: .: 14 S+ Value: ;', 14 Critical Value: -... ' . 10 Sign test results: , Pass Sufficient samples collected: Pass Maximum value <DCGLw: . 'Pass Median value <DCGL,: Pass Mean value <DCGL: . Pass Maximum value <DCGLec: -. -;Pass Total Standard Deviation <=Sigma: .'. 'Pass Criteria comparison results: ; > ,Pass The survey unit passes all conditions: .'.*-.. Pass FR-091D-SUI.SoflSign-UNITY 11/4/04 6:56 AM FR-09 10-01, Revision 0 Page 18 of 21
FR-0910 SU-1 Quantile Plot 0.3 - I.
0.25 -I-N 0-0.2 0 O 00
- Activity (Unitized) 0 6 0.15 O
- vx t.j 4-.-
- Median (Unitized)
- 0 To Co U.0 0.1 U
0.05 -_ ' _ , , , , , _
0 0 25 50 75 100 Percent
One-Sample T-Test Report Page/Date/Time 2 10/13/04 12:55:20 PM Database CAProgram Files\NCSS97\FrO910s.S0 Variable C2 Plots Section Histogram of FR-0910, SU-1 U2 0
.0 E
z Activity (Unitized)
FR-0910-01, Revision 0 Page 20 of 21
One-Sample T-Test Power Analysis Page/Date/Time 2 10113/04 12:56:09 PM Chart Section Retrospective Power Curve 1.0 ._ I I I -.
\ ,
0.8-I I L_-
a) 0.6 - - - -
,I \
0 0-0.4- I ' I \
I ' ' \ I I ' '
0.2- I . \ I I , I .I III 0.0 0.0 0'2 0.4 0.6 0.8 1.0 Survey Unit Mean (Unity)
FR-0910-01, Revision 0 Page 21 of 21