ML043290283

Final Status Survey Release Record FA-1400 Personnel Hatch Footprint Survey Unit 1

ML043290283
Person / Time
Site:	Maine Yankee
Issue date:	11/17/2004
From:	Donna Anderson Maine Yankee Atomic Power Co
To:	NRC/FSME
References
FA-1400
Download: ML043290283 (20)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-1400 PERSONNEL HATCH FOOTPRINT SURVEY UNIT 1 Prepared By: _ .______t___ Date: Io/13/lo4 FSS Engineer - Signature

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MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-1400 PERSONNEL HATCH FOOTPRINT SURVEY UNIT I A. SURVEY UNIT DESCRIPTION Survey Unit FA-1400-01 consists of sub-slab soil, concrete and gravel media below the now demolished Personnel Hatch Building, located at grid coordinates 407483N and 623890E using the Maine State Coordinate (West Zone) NAD 1927, as shown on Map FA 1400 SITE, Attachment 1. The survey unit footprint, following building demolition and removal, was approximately 3 feet below grade.

The Personnel Hatch was a concrete block structure with painted, epoxied concrete floor, painted walls and ceiling with some structural steel. The building contained two rooms, with the larger room housing the steel containment access door that served as the primary personnel access point for the Containment Building during plant operation. The smaller room housed ventilation equipment and filter banks. The Personnel Hatch was located within the Restricted Area and encompassed a footprint area of approximately 182 in2 .

B. SURVEY UNIT DESIGN INFORMATION The area was initially designated a Class 2 land survey unit in accordance with Section 5.2.3 of the LTP, with the excavated foundation footprint classified as one class lower than would have been assigned to the foundation concrete surface. During the performance of the final status survey, radionuclide concentrations were found to exceed the reduced DCGLs for surface soil inside the Restricted Area.' When the direct measurement levels exceeded the DCGLs, the survey unit was reclassified and a new survey designed in accordance with Class I requirements as provided in Section 5 of the LTP.

The survey unit design parameters for FA-1400 as a Class I survey are shown in Table 1.

Given a relative shift of 2.0, it was determined that 15 direct measurements were required for the Sign Test. Measurement locations were based on a systematic square grid with a random start point and are illustrated on the map FA 1400-2a (Attachment 1). All direct measurements consisted of soil samples obtained at the required locations. The samples are analyzed with laboratory gamma spectroscopy.

In accordance with the LTP, scans covering 100% of the 182 in2 area were required for the Class I survey unit. This was accomplished by use of an ISOCS detector configured at a 2-meter distance from the surface to obtain approximately 12-m 2 field of view for each scan.

Locations of the survey scans are shown on map FA 1400-1 b (Attachment 1). The survey instruments used, their MDCs, and scan investigation levels are provided in Attachment 2.

DCGLs for Co-60 and Cs-137 as derived from LTP Rev 3 Table 6-11, taking into account changes inthe activated concrete remediation plans, submitted in the September II, 2003 license amendment (MY Letter to the NRC MN-03-049) and approved by the NRC (letter dated 2/18/2004). The license amendment lowered the surface soil DCGL to 2.39 pCi/g for areas inside the RA.

FA-1400-01, Revision 0 Page 2 of 20

TABLE I SURVEY UNIT DESIGN PARAMETERS Survcy Unit J Design Criteria l Basis Area 182 mz Class I Based on LBGR of 1.195, Number of Direct sigma2 of 0.58 pCi/g, and a Measurements Required 15 relative shift of 2.0.

Type =TypeII = 0.05 Sample Area 12.13 m' 182 ml/ 15 -= 12.13 m Sample Grid Spacing 3.5 m (12.13)v' Scan Grid Area ISOCS scan at 2-meters' Memo TSB 01-07/06/2004 Area Factor 2.4 Class 1 Area, LTP Table 6-12 Scan Survey Area 182 m1 Class I Area -100%

2.2 pCi/g Cs-137 ISOCS investigation levels with Scan Investigation Level 0.8 pCi/g Co-60 detector at 2-meter height 2.39p~ig Cs137LTP Revision 3, Table 6-1 1, DCGL 2.39 pCi/g Cso137 from 09/11/2003 License 0.86 pCilg Co-60 Amendment (MN-03-049) 5.74 pCi.g Cs-137 DCGL x Area Factor for Class I Design DCGLENTc 2.06 pCi/g Co-60 survey unit, per LTP Section 5.6.3 C. SURVEY RESULTS A total of 16 direct volumetric measurements were made and the results are presented in Table 2. All direct measurements were below the DCGL. ISOCS gamma scans were performed at 30 locations using an investigation level of 0.8 pCi/g Co-60 and 2.2 pCi/g Cs-137. The gamma scans were performed for a sufficient count time to achieve a Minimum Detectable Activity of 25% of the DCGL. All identified activity levels were below the investigation scan setpoints. Therefore, no investigations were required.

2 Sigma was determined using the standard deviation for direct soil sample measurement results obtained during the Class 2 survey of FA-1400.

Memo TSB 0 1-07/06/2004, ISOCS Geometries and Investigation Levels FA-1400-01, Revision 0 Page 3 of 20

TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCVg) Uncertainty (pCiog) l Uncertainty Unity Rule FA1400-01-1GOOIVS <5.56E-02 <623E-02 9.57E-02 FA1400-01-1G002VS 1.39E-01 3.33E-02 9.36E-02 2.188E-02 1.67E-0 I FA1400-01-1G003VS 7.74E-02 3.45E-02 <5.71 E-02 9.88E-02 FA1400-01-lGO04VS 6.78E-02 2.95E-02 <6.1 OE-02 9.93E-02 FA1400-01-IGO05VS 2.60E-01 3.77E-02 5.73E-02 1.90E-02 1.75E-O1 FA1400-01-lG006VS 8.1OE-01 8.01 E-02 <6.03E-02 4.09E-0I FA1400-01-1G007VS 2.13E-01 4.54E-02 3.07E-01 3.78E-02 4.46E-0I FA1400-01-1G008VS 1.33E-01 3.52E-02 <6.58E-02 1.32E-0I FA1400-01-1G009VS <5.81 E-02 <5.83E-02 9.21 E-02 FA1400-01-1GOIOVS <6.38E-02 <5.89E-02 9.52E-02 FA1400-01-IGOI IVS 4.12E-02 2.58E-02 <5.95E-02 8.64E-02 FA1400-01-IG012VS <5.49E-02 <5.09E-02 8.22E-02 FA1400-01-IG013VS 1.27E-01 3.81E-02 <5.79E-02 1.21E-0I FA1400-01-IGO14VS 1.56E-01 3.50E-02 1.72E-01 3.29E-02 2.66E-0I FA1400-01-lGO15VS <5.61E-02 <5.71E-02 8.99E-02 FAI400-01-IG016VS <7.1 IE-02 <7.78E-02 1.20E-01 I.49E-01 1ean 8.48E-02 1.61E-0I Median 7.43E-02 5.99E-02 1.lOE-01 Standard Deviation 1.87E-01 6.60E-02 1.14E-01 4.12E-02 5.09E-02 8.22E-02 Range to to to 8.1OE-01 3.07E-01 4.46E-01

"<" indicates MDA value D. SURVEY UNIT INVESTIGATIONS AND RESULTS No investigations were required.

E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample result range, is provided in Table 2. Of the 16 volumetric samples collected, 10 identified Cs-I 37 activity below the DCGL value of 2.39 pCi/g while 4 identified Co-60 activity below the DCGL value of 0.86 pCi/g. All other values were at the MDA. Identified sample activities or Minimum Detectable Activities are listed in Table 2.

The mean and median activities were less than the DCGL for both Co-60 and Cs-i 37. The highest reported values for Co-60 and Cs-137 were less than 50% of the DCGLs.

FA-1400-01, Revision 0 Page 4 of 20

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. The established mean fallout Cs-] 37 background value 4 (0.19 pCi/g) for disturbed soil is larger than the survey unit mean. Hence the annual dose from Cs-137 is 0.0 mrem/y. However, the mean value of 0.0848 pCi/g Co-60 would equate to an annual dose rate of 0.55 mrem/year 5 .

H-lowever, 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 volumetric 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 (Table 1) 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 ESS of this survey unit.

2. The Quantile Plot was generated from the unity value data listed in Table 2. The data set and plot are consistent with expectations for a Class I survey unit. All of the measurements are well below the DCGL of 2.39 pCi/g for land inside the restricted area.

3. A Histogram Plot was also developed based on the unity values. This plot shows a log-nornal distribution with 5 outliers.

4. A Retrospective Power Curve was constructed, based on SS results. The curve shows that this survey unit having a mean residual activity at a 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.

4 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 5).

5 This annual dose equivalent is based on LUP Table 6-11 which shows the contaminated soil in the RA contribution of 5.63 mrem from the 2.39 pCi/g DCGL.

FA-1400-01, Revision 0 Page 5 of 20

G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was initially designed for a Class 2 land survey area. Direct measurements determined that residual radioactivity levels exceeded the allowable levels. Following remediation, the survey was designed as a Class I area; the FSS results were consistent with that classification. The post-remediation direct measurement sample standard deviation was less than the design sigma. Thus, a sufficient number of sample measurements were taken.

II. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 1 was designed and performed using the criteria of the approved LTP Revision 3 Addenda (Reference 1). The only subsequent LTP changes with the potential for impact to this survey unit were provided in the proposed license amendment related to modifications of the activated concrete remediation plan, submitted September I 1, 2003 (Reference 3) and approved by the NRC (Reference 4). Changes represented in this later license amendment were applied during the design and performance of the final status survey of Survey Unit 1.

I. CONCLUSION The FSS of this survey unit was designed based on a Class I designation. 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 DCGLs of 0.86 pCi/g Co-60 and 2.39 pCi/g Cs-137.

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 wvas 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 log-normal distribution, with variance consistent with expectations for a Class I survey unit.

The scan survey design for this survey unit was developed in accordance with the LTP Revision 3 Addenda (Reference 1) and the LTP Supplement on Activated Concrete (Reference 3 and 4) with significant aspects of the design discussed in Section B and Table 1.

Scans conducted with the ISOCS did not identify activity above the scan investigation levels of 0.8 pCi/g Co-60 and 2.2 pCi/g Cs-137. The gamma scans were performed to achieve an MDA of approximately 25% of the DCGLs.

It is concluded that FA-1400 Survey Unit I meets the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.

FA-1400-01, Revision 0 Page 6 of 20

J. REFERENCES

1. 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

2. NRC letter to Maine Yankee, dated February 28, 2003

3. Maine Yankee letter to the NRC, MN-03-049, dated September 11, 2003 (LTP Supplement to LTP Revision 3)

4. Issuance of License Amendment No. 170, NRC letter to Maine Yankee, dated February 18, 2004

5. Maine Yankee PMP 6.7.8, FSS Data Processing and Reporting, Attachment E, Approach for Dealing With Background Radioactivity for Maine Yankee Final Status Surveys

6. Memo TSB 01-07/06/2004, ISOCS Geometries and Investigation Levels FA-1400-O1, Revision 0 Page 7 of 20

Attachment 1 Survey Unit Maps FA-1400-01, Revision 0 Page 8 of 20

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a0 I I 626,000 E Note: Grid based on Maine State Coordinate System Western Corner of Personnal Hatch at Coordinate -407,483N

-623.890E (West Zone) NAD 1927

Decommissioning Team Maine Yankee DecominissioningProjectSurvey Forimn Reapised 7F1400-2a Survey Type: E Characterization El Turnover

• Final Status Survey Survey Area Name: Personnel Hatch Building Personnel Hatch Building Footprint Final Status Survey Direct Points G001-G016 T

-1 I

1.6 3.6 T

3.6 3.6 FA-1400-01, Revision 0 Page IO of 20 N =15, L =3.6 Soil Footprint Total Area - 182 sq-m N=15, L=3.6 Soil Footprint Total Area 182 sq-rn

Maine Yankee Project Sure Formn Map ID#: FA 1400 DP Ref MaFDeconmissioig A Decommissionin_ Team IPI Revised: 7-15-04 Survey Type: l Characterization l Turnover

• Final Status Survey Survey Area Name: Personnel Hatch Building Personnel Hatch Building Footprint Final Status Survey Direct Points Reference Map FA-1400-01, Revision 0 Page 11 of 20 Soil N =15, L N=15, =3.6 L=3.6 Soil Footprint Footprint Total Total Area Area - 182

- 182 sq-m sq-rn

Maine YanKee [anI Map ID#: FA 1400-1b Decommissioning Team lMaine Yankee Decofifsioning ProjectSurvey Fo Revised: 7-14-04 Survey Type: O Characterization E Turnover

• Final Status Survey Survey Area Name: Personnel Hatch Building Personnel Hatch Building Footprint Final Status Survey ISOCS Scans G001 - G030 1.

5rn 1.34 The ISOCS scans are 4.Om 0 circles.

FA-1400-01, Revision 0 Page 12 of 20 Soil Footprint Total Area - 182 sq-rn

Attachment 2 Survey Unit Instrumentation FA-1400-01, Revision 0 Page 13 of 20

TABLE 2-1 INSTRUMENT INFORMATION I ISOCS Detector S/N I Scan MDC (pCi/g) 1 7607 1 0.10to0.35 _

IIPGe Detectors for Lab Analysis of Volumetric Samples Detector Number I MDC (pCi/g)

I FSS-1 l 3.5E-02 to 8.OE-02 I FSS-2 I 3.5E3-02 to 8.OE-02 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DESIGN DCGLEMrc Detector l ISOCS I . Comments Scan MDC 7.75E-02 to 2.05E-01 Co-60 Approximately 25% of (pCi/g) 1.53E-01 to 3.49E-01 Cs-137 DCGL Revised Activated Concrete DCGL 8.60E-01 pCi/g Co-60 DCGL (MN-03-049) and (pCi/g) 2.39E+00 pCi/g Cs-137 Amendment No. 170 (Reference 3 and 4) 8.003-0 p~ig C-60 Memo TSB 0 1-07/06/2004, Investigation Level 2.20E+00 pCi/g Cso137 ISOCS Geometries and Investigation Levels Dcsign DCGLEIMC 2.06E+00 pCi/g Co-60 DCGL x Area Factor for (Pci/o) 5.74E+00 pCi/g Class I survey unit, per LTP from Release Record Table I 57E0pi/Cs17 Section 5.6.3 FA-1400-01, Revision 0 Page 14 of 20

Attachment 3 Investigation Tables (None Required)

FA-1400-01, Revision 0 Page 15 of 20

Attachment 4 Statistical Data FA-1400-01, Revision 0 Page 16 of 20

Survey Package FA-1400 Unit I Soil Sign Test Summary

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-¢-: '>Sg-j.--ialuaion inpit Yt ausl .:;;< :-Hor' --t- omment FYj>L Survey Package: FA-1400 Survey Unit: 01 Evaluator: Anderson DCGL,: 2.39E+00 DCGLemc: 5.74E+00 LBGR: 1.20E+O0 Sigma: 5.80E-01 Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A i ,>.s-6 iiacuia ag e es.-A;w.n- C^H;xi Zlt:1.645 Z.p: 1.645 Sign p: 0.97725 Calculated Relative Shift: 2.0 Relative Shift Used: 2.0 Uses 3.0 if Relative Shift is >3 N-Value: 12 N-Value+20%: 15 A f. va->j1 Data Values Simple i < v-,

i, . 1/2Commets Number of Samples: 16 Median: 1.1 OE-01 Mean: 1.61 E-01 Net Sample Standard Deviation: 1.14E-01 Total Standard Deviation: 1.14E-01 SRSS Maximum: 4.46E-01

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,r Si'n76st Results:.t ' rh~ dtX m Adjusted N Value: 16 S+ Value: 16 Critical Value: 11 Sign test results: Pass J' 5?t'{;." i t>W C~itea Satosfa;o iiX --

Sufficient samples collected: Pass Maximum value <DCGLw: Pass Median value <DCGL.: Pass Mean value <DCGL,: Pass Maximum value <DCGLmc: Pass Total Standard Deviation <=Sigma: Pass Criteria comparison results: Pass The survey unit passes all conditions: Passl FA-1400-SU1-SoilSign.xls 8/17104 9:20 AM FA-1400-01, Revision 0 Page 17 of 20

FA-1400 SU-1 Quantile Plot 0.5 0.45 0.4 ______ ____ _______ +

a)

N 0.35 4-W0z, 0.3 x0 6

• Activity (Unitized) 0.

-W 0.25 co : Median (Unitized) 0

%-0 0.2 0

. 0.15 0.1 * , * , .

0.05 0

0 25 50 75 100 Percent

One-Sample T-Test Report Page/Date/Time 2 10/14/04 3:59:44 PM Database Variable C2 Plots Section Histogram of FA-1400, SU-1 12.000-A,

0. 9.000-E co 0

Q

.0

E z 3.000-3000-u... .

01050 q..i 0.15o 0.250 0.350 0.450 Activity (Unitized)

FA-1400-01, Revision 0 Page 19of20

One-Sample T-Test Power Analysis Page/Date/Time 2 10/14/04 4:00:28 PM Chart Section Retrospective Power Curve 1.0 - - .- - - - - - - - - - -

0.8 -E-.--

0.6 ----

0) 0.4-e 0.2- . 0- 1A 0.0 I I I ty) 0.1 0.3 0.5 0.7 0.9 1.1 Survey Unit Mean (Unity)

FA-1400-01, Revision 0 Page 20 of 20