ML043500269

Final Status Survey Release Record FA-0100-05, Rev 0, Containment Building Survey Unit 5.

ML043500269
Person / Time
Site:	Maine Yankee
Issue date:	12/07/2004
From:	Donna Anderson, Broutigom T, Pillsbury G Maine Yankee Atomic Power Co
To:	NRC/FSME
References
FA-0100-05, Rev 0
Download: ML043500269 (21)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-0100 CONTAINMENT BUILDING SURVEY UNIT 5 Prepared By: _ __ _ Date: 9 a1/2 E Enginee rSignature Printed ffame Reviewed By: Date: ~10 FS$ p Iilt -Signature Printed Name Reviewed By: L. Tha t Date: ,11dao 4 Independent Review - Signature

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MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-0100 CONTAINMENT BUILDING SURVEY UNIT 5 A. SURVEY UNIT DESCRIPTION Survey Unit 5 is located in Survey Area FA 0100, the Containment Building interior. The Containment Building is located in the restricted area between the Fuel Building and the Spray Building centered at site coordinates 407,575 N and 623,810 E. The Containment Building is shown in relation to other major site structures in map FA 0100. All maps referenced in this release record are provided in Attachment I unless otherwise noted.

Survey Unit 5 consists of the nine pipe penetrations between the Spray Building and the Containment Building located from the -4 foot elevation to the 17 foot elevation as well as the 6 inch I.D. neutron detector transfer chute that went from El. -4 foot to the ICI sump. Some of the steel pipes were removed by coring the penetration and a bare concrete surface was left. The physical configuration of Survey Unit 5 in relation to the remaining survey units in the Containment Building is provided in map FA 0100-UNITS (Attachment 1).

The survey unit has a surface area of approximately 21.4 M2 .

B. SURVEY UNIT DESIGN INFORMATION The survey unit was known to have been contaminated to levels in excess of the release limits and required an extensive remediation effort prior to FSS. Given the high probability of residual contamination, the area was designated a Class I survey unit per the LTP.

The survey unit design parameters are shown in Table I below. Given a relative shift of 3.0, it was determined that 14 direct measurements were required for the Sign Test. Each sample location was determined using a fixed square grid with a random start point. Because of the geometry, 16 direct measurement points were specified as shown on map FA 0 100-Us-DIRECTS. Once the direct readings were completed, removable contamination samples were obtained at each measurement location.

The survey was also designed to include 12 scan grids which are shown on map FA 0100-US-SCANS. Each pipe or penetration was designated as a separate grid yielding a total of nine grids. Additionally, there were three more grids assigned to the Neutron Detector Chute.

Because of the variability in pipe or penetration diameters, the scan grids varied in size from 0.86 22 to 3.17 m totaling 21.35 m2 . Instrument scan setpoints were conservatively set below the DCGLENc as shown in Table 2-2 (Attachment 2).

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Background values were established for each particular instrument probe application based on ambient background values in the survey area for the metal penetrations and, in the case of concrete penetrations, previously established ambient and material backgrounds. Material backgrounds for steel contribute little and were thus not included. The background values listed in Table I were used to establish net activity for direct measurements, scan alarm setpoints, and to confirm the scan MDCs used were appropriate.

The instruments used in this survey unit are listed by model and serial number in Attachment 2 (Table 2-1). Scan MDCs are also listed in Attachment 2 (Table 2-2) and are also compared to the DCGL, the investigation level, and the DCGLEMc. As shown in this table, the scan MDC is less than the investigation criteria in all cases, thus providing high confidence (95% or higher) that an elevated area would be detected in the scanning process. Since the investigation level at the alarm setpoint was always less than the design DCGLEmC, no EMC sample size adjustment was necessary.

TABLE 1 SURVEY UNIT DESIGN PARAMETERS

[ Survey Unit Design Criteria I Basis Area 21.4 m2 < 2000 m', Class I Based on an adjusted LBGR of

. ~79,000 dpmulOO cm, sigma' of Number of Direct Measurements 16,853 dpmulOO cm1,andart Required Requiredshift 14 s6,8f53ofdfp~m/I 3.0. 00 cm, and a relative Type I= Type II = 0.05 Sample Area 1.53 m 21.4 m' / 14 samples' Sample Grid Spacing 1.23 m (1.53)"'

Scan Grid Area Varies' No limits Area Factor 32.6 50 m'/1.53 m 2 per LTP, Rev. 3:

Scan Survey Area 21.4 m' Class 1 - 100%

Background e - $ W@ K 43-68 23" - 29" Metal Pipe 656 dpm/ I00 cm' Ambient only 43-68 6" - 10" Metal Pipe 1,031 dpm/100 cm' Ambient only 43-68 8" Concrete Penetration 3,968 dpml100 cm' Ambient and Material 43-68 24" Concrete Penetration 2,830 dpm/1 00 cm' Ambient and Material Scan Investigation Level DCGL See Table 2-2 (Attachment 2)

DCGL 100,000 dpmlOO cm' LTP, Rev. 3 Design DCGLEMCc 3,260,000 dpml100 cm- LTP, Rev. 3 Design sigma is listed in LTP Table 5-IA, Containment El. -2 ft., AOIOO (LTP, Revision 3).

2 This survey unit was designed for N=l 4 samples per MARSSIM Table 5.5.

3 Each pipe or penetration, except the Neutron Detector Chute, has been designated as a scan grid (see Section B).

The detector chute was divided into three grids.

LTP, Rev. 3 refers to the LTP submitted in October 2002 (Reference I) as amended by the Maine Yankee Addenda of November 2002 (Reference 2). LTP, Rev. 3 was approved by the NRC in February 2003 (Reference 3).

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C. SURVEY RESULTS While 14 direct measurements were required, 16 were made in Survey Unit 5. All direct measurements were less than the DCGL. The resulting data are presented in Table 2 belowv.

One verified alarm was received during the surface scans using the 43-68 probe. The investigation of verified alarms is discussed in the following section.

TABLE 2 DIRECT MEASUREMENTS Gross Activ Net Activity Sape Number c~~7 (Table 1 Background Subtracted)

(dpm/100 cm) (dm/100 CM2)

FAOl00-5-M001 456 -200 FA0100-5-M002 559 -97 IA0100-5-M003 559 -97 FA0100-5-M004 521 -135 FAOI0O-5-CO05 3,540 711 FAO100-5-C006 3,078 248 FAO100-5-C007 2,374 -455 FAOIOO-5-C008 2,581 -248 FAOlOO-5-M009 494 -162 FAO100-5-M010 534 -121 FAO100-5-CO11 4,830 861 FAO100-5-M012 637 -19 FAOIOO-5-C013 3,237 407 FAOlOO-5-C014 3,423 594 FAOI00-5-M015 2,177 1,146 FAI0O0-5-C016 648 -8 Mean 1,853 151 Median 1,413 -58 Standard Deviation 1,463 459 Range 456 - 4,830 -455 -1,146 D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The scan identified one area of potentially elevated activity. Scan grid location M012 in the Neutron Detector Chute alarmed and was determined to be due to high gamma activity associated with activated concrete and not surface activity in the ICI sump. Investigation results are summarized in Attachment 3 (Table 3-1). The investigation is discussed in more detail in Section E to follow.

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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. Without subtracting background, all direct measurement results were below the DCGL. The maximum direct sample result with background subtracted was equivalent to 1,146 dpm/100 cm 2 . When adjusted for background (Table I background subtracted), the mean residual contamination level is 151 dpm/l 00 cm 2 .

This is equivalent to an annual dose of 0.00008 mrem/y. 5 One verified alarm was investigated, as shown in Table 3-1 of Attachment 3. This alarm was at scan grid location M012 (6" diameter steel) in the Neutron Detector Chute. The instrument had an alarm setpoint of 23,500 cpm, and alarmed on a reading of 32,400 cpm. After the alarm was verified, the grid was rescanned with a shielded probe yielding 28,700 cpm. The difference between the shielded and the original measurement was 3,700 cpm which was significantly less than the alarm setpoint of 23,500 cpm. This indicates that high gamma activity associated with activated concrete caused the alarm and not surface contamination. This result was not unexpected because the measurement location is in the ICI sump. The difference of 3,700 cpm is equivalent to 15,703 dpm/100 cm 2 and is significantly less than the DCGL of 100,000 dpmf/1 00 cm2 .

F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with Survey Unit 5, 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 shown in the table, all of the key release criteria were clearly satisfied for FSS of this survey unit.

2. The Quantile Plot was generated from direct measurement data listed in Table 2 and indicates general symmetry about the median. The data set and plot are consistent with expectations for a Class I survey unit. There is no reason to conclude that the data set represents other than random variations in a Class 1 survey unit. It also should be noted that the maximum net activity (1,146 dpm/100 cm2 at location MOI5) is well below the DCGL of 100,000 dpm/100 cm .

3. A histogram plot was also developed on the direct measurement values. This plot shows that the direct data were essentially a normal distribution.

5 This annual dose equivalent is based on LTP Table 6-11 which shows the BOP embedded piping dose contribution (for embedded piping contaminated at the DCGL) to be 0.0511 mrem/y.

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4. A Retrospective Power Curve was constructed based on FSS results. The curve shows that the 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, removable contamination samples were obtained at each (direct) measurement location. In that this survey unit involved embedded pipe and not a standing building, the removable contamination measurements were not applicable to release decisions for the survey unit. However, the samples were obtained and evaluated, indicating alpha activity less than MDA values (i.e., < 3.2 dpm/100 cm 2 ) and the maximum beta activity at 8.1 dpmIlO0 cm 2 . Thus, in comparison with the mean survey unit net activity (Table 2), the removable contamination sampling effort indicated that the majority of activity is fixed.

G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class I area; the 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.

11. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 5 was designed and performed using the criteria of the approved LTP, Revision 3 Addenda (References 1, 2, and 3) and the license amendment related to modifications of the activated concrete remediation plan submitted September 11, 2003 (Reference 4).

I. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class I 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 beta direct measurements were less than the DCGL of 100,000 dpm/100 cm 2 .

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 variance consistent with expectations for a Class I survey unit.

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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 one verified alarm (Section C) for evaluation. Attachment 3 shows the area identified by the verified alarm and provides the result of the investigation actions. The area under investigation was determined to be the result of high gamma activity in the activated concrete found in the ICI sump. The elevated measurement comparison was not performed.

In addition, while not part of the release decision criteria, removable contamination sampling confirmed that the majority of remaining activity in this basement survey unit was fixed.

It is concluded that FAOlI00 Survey Unit 5 meets the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.

J. REFERENCES

1. Maine Yankee License Termnination Plan, Revision 3, October 15, 2002

2. Maine Yankee letter to NRC, MN-02-061, dated November 26, 2002

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

4. Maine Yankee letter to NRC, MN-03-049, dated September 11,2003 FA0 1O00-05, Revision 0 Page 7 of 21

Attachment I Survey Unit Maps FA-0100-05, Revision 0 Page 8 of 21

Maine Yankee ankeeAlahie Yankee Decommissionhig ProjectStirvej, ForylMapI': A00 Maine Decommissioning Team I iD t: FA 0100 Survey Type: - Characterization - Turnover U Final Status Survey I Survey Area Name: Reactor Containment Building Note: Grid based on Maine State Coordinate System (West Zone) NAD 1927 623,000 E 623,500 E 624,000 E 624,500 E 625,000 E Survey Area: FA 0100 MN 4-- ~ N FA-0I00-05, Revision 0 Page 9 of 21

Mne Yank ine Yankee Decommissioning Project Survey a Map ID# FA 0100-UNITS Decomniss:aQioin Teamn I Tlai overh 3oFissloig onetCoirvnyet BldgI S-u~veylype: [ Veriiicotion E] uinovel [K Find Stn~tu,.Sur'e eao'me:

Ai7- Containment Bldg. (Internal) I' TeI.& below I

I FA-I100-05, Revision 0 Page IOof 21

Maine Yankee , D P S Decorrynissioning Team Il laine lMp D#FA lOO-U5-DIRECTS IankeeDecomjnissionirzgProjectS.rveyAap SuveyType: n Verification E Turnover , Final Siotus Survey ISurveyAiea Name: Containment Bldg. Survey Unit 5 Col 1 M012 201 3 C014 6.25" 6.25" 3 6.2.5",x lo 184° 00

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cl..I MOI 6 M009 Mol0 11.75" 11.75" A I 1.75" X X 11350 1 1670 28e6 450 0 (d 00 00 Kr WD. Kl 00

. e co CI"R s30 FA-O100-05, Revision 0 Page II of 21

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Attachment 2 Survey Unit Instrumentation FA-0100-05, Revision 0 Page 13 of 21

TABLE 2-1 INSTRUMENT INFORMATION E-600 S/N I Probe S/N (type)

I 1933 1 177992 (43-68-5) 1929 1 177991 (43-68-5)

TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DESIGN DCGLEIMC Detector l 43-68 Metal Pipe 43-68 Concrete Penetration

. 23"-29"9 6" - 10"9 V" 2499 Scan MDCU (dpm/100 cm 2 ) 810 1,274 2,904 2,071 DCGL (dpm/l00 cm 2 ) 100,000 100,000 100,000 100,000 Investigation Level 99,989 99,992 99,981 100,000 (Alarm Setpoint)

(dpm/1 00 cm 2 ) (DCGL) (DCGL) (DCGL) (DCGL)

Design DCGLENirlc (dpm/1 00 cm) 3.26E+6 3.26E+6 3.26E+6 3.26E+6 (from Release Record Table 1) 6 Scan MDCs taken from LTP Table 5-6 and corrected for changes in efficiencies due to penetration geometry and materials.

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Attachment 3 Investigation Table FA-0100-05, Revision 0 Page 15 of 21

TABLE 3-1 INVESTIGATION TABLE Scan Alarm i Scan Investigation DCGLENc Comparison ElritdNo.a Alarm Setpoint Alarm Value Scaler Area DCGLEMC Elevated Area DCGLENIC (nGrid (Instrument ment Used) (cpm)

___________Used)___

(cpm) (cpm) (CM) AF (dpm/100 cm2l Activity2 (dpm/100 cm 2 Comparison Fraction M012 (43-68-5) 23,500 32,400 2S,700e N/A N/A N/A < DCGL N/A Survey Unit N/A N/A N/A N/A N/A DCGL Survey Unit 0.00151 Remainder 100,000 Mean = 151 Total 0.00151 7 This scan was conducted on the far end of the neutron detector chute which was influenced by the high gamma field created by the activated concrete surrounding the ICI sump into which the chute penetrates. The scan was repeated using a beta-shielded detector and the scan value was 28,700 c/m. The net beta response between the two readings was 3,700 c/m which was similar to the scan values taken above the activated portion of the chute (i.e., 4,200 c/m and 2,750 c/m). The neutron detector chute was determined not to have surface contamination above the DCGL.

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Attachment 4 Statistical Data FA-0I00-05, Revision 0 Page 17 of 21

Survey Package FA-O100 Unit 5 Surface Sign Test Summary

-: f- ,*EValuatibn Input Values - iComments!- -

Survey Package: FA-010 Containment Building Survey Unit 05 Evaluator: GP DCGL,: 100,000 DCGLemlc: 3,260,000 LBGR: 79,00q Sigma. 6,853 Type I error . .0.0' Type II error 0.05 The following efficiencies were used:

Total Instrument Efficiency: 29.40/, 18.7%,8.2%,l 1.5%

Detector Area (cm2 ): 12 based on pipe size & material Material Type: N t hoosing 'N/A' sets material background to "0w

• -.  ;;.- Calculated V alu es;':3-m

.- ..k- .............. _____________,,__________________r _- _________

.Z: :1.64!_____________________

1.64!

Sign p: 0.99865 Calculated Relative Shift: 3.

Relative Shift Used: 3.O Uses 3.0 if Relative Shift >3 N-Value: 11 N-Value+20%: 14

-. -Stt ....... C mments .. ;- 6 ;,.  ;

Number of Samples 16 Median -58 Mean 151 Net Static Data Standard Deviation: 459 Total Standard Deviation: 45 SRSS Maximum. 1,14 Adjusted N Value: - 16 S+ Value: 16 Critical Value: 11 Sufficient samples collected: . -, Pass Maximum value <DCGLW. ., Pass Median value <DCGL, . Pass Mean value <DCGLW . Pass Maximum value <DCGLe,,C, . 'Pass Total Standard Deviation <=Sigma:, Pass Sign test results-: Pass The survey unit passes all conditions:- Pass FA-0100-05, Revision 0 Page 18 of 21

FA-0100 SU-5 Quantile Plot 1400 1200 E 1000 0 800

.- ft 600

• Activity (dpm/1 00 UO IVs 0 cm2)

._ 400

" a0

-Median (dpm/100 t'3 <.

-._ 200 32.

0 cm2) 0 ,

C. -200 , , ,_

-400

-600 .1 0 25 50 75 100 Percent

One-Sample T-Test Report Page/Date/Time 2 8/5/04 7:52:26 AM Database Variable C2 Plots Section Histogram of FA-0100, SU-5 U,

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Activity (dpm/100 cm2)

FA-0I00-05, Revision 0 Page20 of 21

One-Sample T-Test Power Analysis Page/Date/Time 2 8/5/04 7:50:27 AM Chart Section Retrospective Power Curve 1.0A F 0.8-a) 0.6 L.

0 0.4 0.2 0.0 0

20800 4C &00 60100 80100 o0d 10 0 Survey Unit I Aean (dpm/100 cm2)

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