ML090510029

Confirmatory Survey Results for Activities Performed in December 2007, Rancho Seco Nuclear Generating Station

ML090510029
Person / Time
Site:	Rancho Seco
Issue date:	03/12/2008
From:	Adams W Oak Ridge Institute for Science & Education
To:	John Hickman NRC/FSME/DWMEP/DURLD
References
1695-SR-02-0, RFTA 06-003
Download: ML090510029 (28)

Text

CDR S JE OAK RIDGE INSTITUTE FOR SCIENCE AND EDUCATION March 12, 2008 Mr. John Hickman Mail Stop: T-8F5 Office of IFederal and State Materials and Env'ironmental Nlanagenment Programs U.S. Nuclear Regulatory Commission 11545 Rockville Pike Rockville, il1) 20852

SUBJECT:

INTERIM LETTER REPORT-CONFIRMATORY SURVEY RESULLTS FOR ACTIVITIES PERFORMED IN DECEMBER 2007; RANCHO SECO NUCLEAR GENERATING STATION, HERALD, CALIFORNIA DCN 1695-SR-02-0 (DOCKET NO. 50-312, RFTA NO.06-003)

Dear Mr. I-lickman:

The Oak Ridge Institute for Science and lEducation (ORISE-) performed confirmatorv survey activitics on the Auxiliary Building structural surfaces (Rooms 18, 50 and 53 and Vailts 30, 31, 34 and 35).

portions of the Acid \Vaste Piping system, and two exterior soil areas 1Otifall Area and the Rcgencrant I-Told-Up Tank (RI-IUT) Auxiliary 13uilding Soil Areal at tile Rancho Seco Nuclear Generating Station in Herald, California on Decemlber 10 through 13. 2007. These sun'ey activiiies were requested and approved by the U.S. Nuclear Regulatory Commission (NRC'). E'nclosed isan interim letter report thai summarizes OR ISE's survey procedures and preliminary reselts of the confirmiatory survey.. T'h1e surveys included beta and gamma surface scans, direct measurements for total net beta actiivty. and smears for removable alpha and beta activity within the Auxiliary Building; embedded piping gamma scans within the Auxiliary Building; and limited gamma scans and the collection of soil samples in the Outfall and RHIUT Auxiliary Boliler L.and Areas.

If you have any questions, please direct them io me at 865.576.0065 or Sarah Roberts al 865.2,11.8893.

Sincerely, Wade C. Adams ORISE 1-Ieahih Physicist/ Proijec Leader Survey Projects WCA:bf Enclosure I. Ablc1quist, ORISE 1.. Knox-Davin, NRC/IFSIIX/T\EN 8A23 S. Roberts. ORISIX F'. Garcia, NRC/Regionl IV W. Riley. ORISE l.Bailey, ORIStIL File 1695 T. 'ctlngblood, N RC'/I'SMB/D\M EPI/T\FN 8 P5 Distributioni appro)val and enncurrence: Inilial.k n I *tcclttnic-.l\alit~ngeic11i tuil un N'icIbr -. ' N&

I nbi ra ton- Nanage'r tQucilv Mn~agic r P. 0 .Boicx Voice: 86.56.01 865.376.0065 Fax: 86.5.241.3:197 Fax: 865.41.3497l-mail: \'Qacle.A.:, (lii5 7h, ,,:, t tori,

INTERIM LETTER REPORT CONFIRMATORY SURVEY RESULTS FOR ACTIVITIES PERFORMED IN DECEMBER 2007 RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA INTRODUCTION The Sacramento Municipal Utility District (SMUD) operated the Rancho Seco Nuclear Generating Station (RSNGS) from 1976 to 1989 under Atomic Energy Commission Docket Number 50-312 and License Number DPR-54. In August 1989, SMUD notified the U.S. Nuclear Regulatory Commission (NRC) that they shut down RSNGS permanently. In May 1991, SMUD submitted the Rancho Seco Decommissioning Plan which was approved by the NRC in March 1995. SMUD began decommissioning activities in February 1997 and completed transfer of all the spent nuclear fuel in August 2002 (SMUD 2 0 06a).

In April 200,6, SMUD submitted a license termination.plan (LTP) that was recently approved by the NRC on November 26, 2007 (SMUD 2006a and NRC 2007). SMUD currently is conducting decontamination efforts and performing final status surveys (FSS) on the remaining structural surfaces and in open land areas.

The NRC requested that the Independent Environmental Assessment and Verification (IEAV)

Program of the Oak Ridge Institute for Science and Education (ORISE) perform confirmatory surveys of structural surfaces and the Acid Waste System drains in the Auxiliary Building at the RSNGS (Figures 1 and 2). While on site, the NRC site representative also requested that ORISE perform cursory gamma surface scans and collect soil samples at the Outfall Area and the Regenerant Hold-Up Tank Auxiliary Boiler Land Area (RHUT Area). The confirmatory surveys were performed during the period of December 10 through 13, 2007.

PROCEDURES Confirmatory surveys were performed in accordance with a site-specific survey plan that was submitted to and approved by the NRC (ORISE 2007a). The site-specific survey plan follows the guidance provided in the IEAV Survey Procedures and Quality Program Manuals (ORISE 2007b and ORAU 2007).

In the Auxiliary Building, ORISE judgmentally selected four of the eight vaults (Figures 3 through 5), three rooms (Figures 6 through 8), two Acid Waste System drains (Figures 9 and 10), and various pipe penetrations for confirmatory surveys based upon preliminary FSS results. At the request of the NRC site representative, ORISE also performed limited radiological surveys of the Outfall and RHUT Areas (Figures 11 and 12).

SURFACE SCANS Auxiliary Building Structural Surfaces Gamma surface scans were performed using sodium iodide, thallium-activated [NaI(Tl)] gamma scintillation detectors coupled to ratemeters with audible indicators. Beta surface scans were performed using large area gas proportional, hand-held gas proportional, and Geiger-Muller (GM)

Rancho Seco Nuclear Generating Station 1695-SR-02-0

detectors coupled to ratemeter-scalers with audible indicators. Particular attention was given to cracks, joints, embedded piping openings and horizontal surfaces in the evaluated structural surfaces where material may have accumulated.

Drains and Pipe Penetrations Limited qualitative gamma scans were performed in portions of two 2" inner diameter (ID) Acid Waste Systems drain lines on the -20 foot level elevation and in numerous pipe penetrations within the vaults and rooms that were part of these survey activities. ORISE recorded the gamma scan range for the Acid Waste System drains and the pipe penetrations. Gamma scans were performed using a cesium iodide, thallium-activated [CsI(T1)] gamma scintillation detector coupled to a ratemeter with an audible indicator.

Outfall and RHUT Areas Gamma scans of the soils within the excavated Outfall Area and immediately adjacent to the excavated area and within the RHUT Area were performed using a NaI(Tl) gamma scintillation detector coupled to a ratemeter with an audible indicator.

SURFACE ACTIVITY MEASUREMENTS Based on beta and gamma surface scan results, direct measurements for beta activity were performed at 26 judgmentally-selected locations on the evaluated structural surfaces within the Auxiliary Building which were available for confirmatory survey activities. Direct measurements were performed using hand-held gas proportional detectors coupled to ratemeters-scalers. A smear sample for determining removable gross alpha and gross beta activity levels was collected from each direct measurement location. Direct measurement and smear locations are. indicated, on Figures 4 through 8.

SOIL SAMPLING Based on gamma scan results, ORISE judgmentally collected two soil samples from the Outfall Area; one sample to the east and one sample to the west, both immediately adjacent to the remediated portion of the Outfall Area. Also based on ORISE gamma scan results, ORISE asked SMUD personnel to collect a soil sample from an area of elevated gamma radiation (suspected to possibly be a discrete particle) in the RHUT Area and to provide analytical results to ORISE.

SAMPLE ANALYSIS AND DATA INTERPRETATION Radiological data and sample media were returned to the ORISE laboratory in Oak Ridge, Tennessee for analysis and interpretation. Radioassays were performed in accordance with the ORISE Laboratory Procedures Manual (ORISE 2007c). The soil samples were analyzed by gamma spectroscopy for the primary radionuclides-of-concern (ROC), Co-60 and Cs-137. However, spectra were also reviewed for additional gamma-emitting fission and activation products associated with the RSNGS and other identifiable total absorption peaks. The soil sample results were reported in units of picocuries per gram (pCi/g). Smear samples were analyzed for gross alpha and gross beta activity using a low-background gas proportional counter. Smear results and direct measurements for total surface activity were converted to units of disintegrations per minute per 100 square centimeters (dpm/100 cm 2). Since a pipe detector efficiency was not required, Rancho Seco Nuclear Generating Station 1695-SR-02-0 2

embedded piping scan data were reported in units of counts per minute (cpm) to compare with SMUD's gross gamma cpm results.

FINDINGS AND RESULTS AUXILIARY BUILDING STRUCTURAL SURFACES The scan percent coverage and room area classifications are provided in Table 1. Beta surface scans determined that localized areas of residual elevated beta-gamma surface activity were present on floor and lower wall surfaces within the evaluated survey units (SUs). With the exception of direct measurement Location 14 in Room 18, residual surface activity was limited to small areas that were interspersed throughout the rooms. Due to the elevated beta and gamma surface activity levels determined at Location 14, SMUD and NRC personnel were notified and SMUD personnel remediated the location.

Beta measurements were performed at locations of residual elevated beta-gamma surface activity detected during surface scans. With one exception, total net beta activity measurements ranged from 130 to 16,000 dpm/100 cm 2 . The one exception was at Location 14 in Room 18, which had a total net beta activity of 110,000 dpm/ 100 cm 2 . It was determined that the residual beta activity was due to a discrete particle (0.22 pCi/g of Cs-1 37 and 0.0008 pCi/g of Co-60) 1; the discrete particle was removed and the post-remedial total net beta activity was 1,100 dpm/100 cm 2 . Removable gross alpha.and gross beta activity ranged from 0 to 5 and -3 to 8 dpm/100 cm 2 . Surface activity and removable activity level results are presented in Table 2.

DRAINS AND PIPE PENETRATIONS A comparison of ORISE and SMUD gamma scan results for the Acid Waste System Drain Line 4-2-15 indicated elevated gamma radiation levels, at approximately the same length/depth and levels as reported by SMUD personnel in the preliminary final status survey (FSS) data packages.

However, gamma scans of Acid Waste System Drain Line 4-1-12, Segment 1 (originally numbered incorrectly by SMUD as Drain Line 4-1-13) indicated a large discrepancy between ORISE and SMUD data in the gamma scan range for the 0 to 8 foot portion of the pipe. SMUD's results, although more conservative than ORISE's results, were thirteen times higher than the ORISE results. The reason for this discrepancy is unclear and ORISE recommends further evaluationof this drain line during a future confirmatory survey trip. The ORISE confirmatory and SMUD gamma scan ranges are provided in Table 3.

Gamma scans of numerous pipe penetrations within the evaluated SUs indicated that gamma radiation levels ranged from 200 to 1,200 cpm. For comparison, the CsI(Tl) detector background range for the conduits along the east side of the Turbine Building at the +40 level elevation ranged from 200 to 800 cpm. The ORISE gamma scan ranges for the pipe penetrations are also provided in Table 3.

OUTFALL AND RHUT AREAS Gamma scans of the remediated portion of the Outfall Area and the immediately adjacent areas detected residual elevated gamma radiation levels to the west and east of the remediated portion of Electronic mail from G. Pillsbury (SMUD) to W. Adams (ORISE); January 14, 2008.

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the Outfall Area. A soil sample was collected from each of these locations. The radionuclide concentrations for the two soil samples collected immediately adjacent to the remediated portion of the Outfall Area ranged from 0.32 to 0.49 pCi/g for Co-60 and 34.9 to 47.1 pCi/g for Cs-137. The confirmatory radionuclide concentrations for the soil samples are provided in Table 4.

Gamma scans of the RHUT Area indicated that the vast majority of the surface soil was at background levels. The one exception was along the west perimeter of the area where a small location indicated elevated gamma radiation levels at approximately 40 times the average background. SMUD and NRC personnel were notified of this finding and SMUD personnel remediated the location and collected a soil sample. SMUD analyzed the RHUT soil sample and determined that the sample contained 66 pCi/g of Co-60. The sample was further divided and SMUD isolated a discrete particle that was counted as a point source and reported the particle activity as 0.485 ýtCi of Co-60; the recount of the soil sample (minus the discrete particle) indicated background levels.2 COMPARISON OF SURVEY RESULTS WITH GUIDELINES STRUCTURAL SURFACE ACTIVITY LEVELS The major contaminants identified by SMUD at RSNGS are beta-gamma emitters-fission and activation products-resulting from reactor operation. Cesium-137 and Co-60 have been identified during characterization as the predominant radionuclides present on structural surfaces. SMUD developed site-specific derived concentration guideline levels (DCGLs), which were recently approved by the NRC, based on a dose modeling to future occupants not to exceed 25 mrem/year total effective dose equivalent (TEDE) as presented in Section 6 of the LTP (SMUD 2006a and NRC 2007). The DCGLs for surfaces were modified by SMUD to reflect the ratio of radionuclide concentrations (account for the presence of unmeasured contaminants based on contaminant ratios) in the specific SUs that were being evaluated. The applicable surface activity guidelines for the evaluated structural surfaces for these surveys are provided in Table 5. These DCGLs were provided in the preliminary FSS data packages for each evaluated SU and were derived from the LTP and decommissioning technical basis .document (DTBD)-05-015 (SMUD 2006a and b).-

Confirmatory survey data for Auxiliary Building structural surfaces were compared with the site-specific DCGL for the evaluated Auxiliary Building SUs. One of the 26 direct beta activity measurement results on the concrete structural surfaces exceeded the Gross Beta DCGL of 43,000 dpm/100 cm 2 . Using the gross activity DCGL as determined in DTBD-05-015 (SMUD 2006b) and the area factor determined for each SU, SMUD calculated Design DCGL elevated measurement comparison (DCGLEMc) values which are also provided in Table 5. All confirmatory direct surface activity measurements on the Auxiliary Building structural surfaces in the evaluated SUs were within the site-specific SU DCGLFMC as provided by SMUD in the preliminary FSS data packages. However, it was determined that the elevated beta surface activity at Location 14 in Room 18 was from a discrete Cs-137 and Co-60 particle; hence, the particle was remediated by SMUD personnel while ORISE was on site and a confirmatory, post-remediation direct measurement was performed with the results being well within the gross activity DCGL.

2 Electronic mail from E. Ronningen (SMUD) to W. Adams (ORISE), RE: RHUT Area Contamination; December 20, 2007.

Rancho Seco Nuclear Generating Station 4 1695-SR-02-0

DRAIN LINES AND PIPE PENETRATIONS Co-60 is the primary ROC within the embedded piping. SMUD has established a dose-based restriction for embedded piping not to exceed 25 mrem/year that assumes a building occupancy scenario within rooms where embedded piping is present. The corresponding modeled DCGL is 2 100,000 dpm/100 cm 2 . SMUD's grouting action level for embedded piping is 21,000 dpm/100 cm (SMUD 2007).

ORISE's confirmatory drain line and pipe penetration resultswere not directly compared to the embedded piping DCGL; instead, since ORISE and SMUD used the same Ludlum Model 44-159 CsI(T1) detector, ORISE compared gross gamma scan readings with either SMUD's preliminary FSS data package gamma scan results for each surveyed pipe at various depths or with background levels as determined during a previous ORISE confirmatory survey (ORISE 2007d).

Confirmatory survey data for the Acid Waste System drain lines were compared with the preliminary FSS data package gross gamma cpm results. The confirmatory gamma scan results indicated that ORISE gross gamma radiation levels within the drain line pipes were consistent with the SMUD preliminary FSS data package results for Drain Line 4-2-15. SMUD's gross gamma cpm results for Drain Line 4-1-12, Segment 1 were thirteen times higher than the ORISE gross gamma cpm results; the results for this drain line need to be re-evaluated during the next ORISE confirmatory survey.

Gamma scans of the other evaluated Auxiliary Building pipe penetrations that were part of these survey activities did not detect gamma radiation levels in excess of the detector background.

SOIL SAMPLES Table 6-5 (Table 6) from the LTP provides the single nuclide DCGL's for soil at RSNGS. The DCGLw is 12.6 pCi/g for Co-60 and 52.8 pCi/g for Cs-137 (SMUD 2006a). The Outfall Area soil sample concentrations were below the respective single radionuclide DCGLs. The soil sample collected by SMUD personnel from the location of elevated residual gamma radiation detected by ORISE personnel in the RHUT Area was analyzed by SMUD; SMUD's analyses indicated that the sample (containing 66 pCi/g of Co-60) exceeded the DCGL for Co-60. The sample was further divided and a discrete particle containing 0.485 iCi of Co-60 was identified by SMUD.

SUMMARY

During the period of December 10 through 13, 2007, ORISE performed confirmatory radiological survey activities which included beta and gamma surface scans, beta activity direct measurements, and removable gross alpha and gross beta activity measurements on structural surfaces within the Auxiliary Building; gamma scans within Auxiliary Building embedded piping; and, gamma scans and the collection of soil samples from the Outfall and RHUT Areas.

Beta and gamma surface scans identified several areas of elevated beta surface activity on the structural surfaces of the evaluated SUs with the Auxiliary Building. With one exception, additional investigation of these locations indicated that the majority of the elevated surface activity levels were attributable to localized areas of residual beta-gamma radiation within the matrix of the concrete media. In general, the elevated surface activity was limited to small areas that were interspersed throughout the rooms. The one exception was a discrete particle of Cs-137 and Co-60 that was found in Room 18. Direct measurements were performed at 26 locations. As mentioned above, Rancho Sect Nuclear Generating Station 1695-SR-02-0 5

only one direct measurement exceeded the site-specific gross beta DCGL but all were within the DCGLMc criteria. A review of the preliminary FSS data package for Room 18 indicated that SMUD personnel did not identify the elevated residual beta and gamma radiation levels from Location 14 in Room 18. Therefore, the results of the confirmatory survey activities for the evaluated structural surfaces of Room 18 in the Auxiliary Building did not confirm the radiological status of the SU as presented in the licensee's preliminary Room 18 FSS data package. SMUD personnel were notified and are investigating the confirmatory finding in Room 18. The confirmatory survey results for Rooms 50 and 53 are in agreement with the radiological status of these SUs as presented in the licensee's preliminary FSS data packages.

Gamma surface scans of the evaluated Auxiliary Building pipe penetrations did not indicate any areas of elevated gamma radiation levels; the scan results within Acid Waste System Drain Line 4-2-15 were consistent With the results presented in the preliminary FSS data packages for that drain.

However, the gamma scan results for Acid Waste System Drain Line 4-1-12, Segment 1 were not in agreement with the preliminary FSS results. Further investigations by SMUD indicated that Drain Line 4-1-13 had been removed and the preliminary FSS results for Drain Line 4-1-12, Segment 1 were erroneously reported as the results for 4-1-13 (Refer to Figure 9). Due to this discrepancy, SMUD re-surveyed Segments 1 and 2 of Drain Line 4-1-12 and provided preliminary results to ORISE on February 12, 2008.' SMUD's gamma scan range for the 0 to 8 foot length of Segment 1 is thirteen times higher and not in agreement with ORISE's gamma scan results (Table 3). Based on the discrepancy between the ORISE confirmatory and SMUD FSS gamma scan ranges and the confusion with the incorrect numbering of the drain line, ORISE recommends that a side-by-side instrument comparison be performed in this drain line during a subsequent confirmatory survey trip.

The soil sample results from the Outfall Area were below the individual radionuclide DCGLs and meet the soil release criteria. The SMUD radiological analyses of the soil sample from the RHUT area exceeded the soil DCGL for Co-60. SMUD personnel are performing further investigations within the RHUT Area.

3 Electronic mail from E. Ronningen (SMUD) to W. Adams (ORISE), RE: Survey of Acid Waste Line 4-1-12; February 12, 2008.

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FIGURES Rancho Seco Nuclear Generating Station 1695-SR-02-0

1695-001 (2)

-7, CALIFORNIA 70 505 EROSEVILLE 505 80 RANCHO SECO NUCLEAR 50L~

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NOT TO SCALE Figure 1: Location of Rancho Seco Nuclear Generating Station, Herald, California Rancho Seco Nuclear Generating Station *8 1695-SR-02-0

1695-002 (2)

SPRAY PONDS COOLING TOWERS

, TURBINE BUILDING

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, REACTOR BUILDING CHLORINE BUILDING /-"

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NOT TO SCALE Figure 2: Plot Plan of the Industrial Area at Rancho Seco Nuclear Generating Station 1695-SR-02-0 Rancho Seco Nuclear Generating Station 9

Figure provided by SMUD.

N NOT TO SCALE Figure 3: Plot Plan of Auxiliary Building Vaults - Survey Units F8130401 and F8130411 Rancho Seco Nuclear Generating Station 10 1695-SR-02-0

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MEASUREMENT/SAMPLE LOCATION N E Single Point - Floor A

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MEASUREMENT/SAMPLE LOCATION N G Single Point - Floor Single Point - Lower Wall NOT TO SCALE A Single Point - Upper Surfaces

[] Pipe Penetration Figure 5: Survey Unit F8130411, Vaults 34 and 35 - Direct Measurement and Sample Locations Rancho Seco Nuclear Generating Station 12 1695-SR-02-0

I Figure Provided by SMUD MEASUREMENT/SAMPLE LOCATION N Single Point - Floor NOT TO SCALE Figure 6: Survey Unit F8130201, Room 18 - Direct Measurement and Sample Locations Rancho Seco Nuclear Generating Station 13 1695-SR-02-0

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TABLES Rancho Seco Nuclear Generating Station 1695-SR-02-0

TABLE 1 SURVEY UNIT CLASSIFICATION AND SCAN COVERAGE FOR SURVEYED ROOMS IN THE AUXILIARY BUILDING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Auxiliary Percent Scan Coverage Building Class Gamma Survey Floor/Lower BetaF Beta Beta Unit/Rooma Wall Floor Lower Wa Upper Surfaces Vault 30 1 ___b 100 75 5 Vault 31 1 --- 100 75 5 Vault 34 1 100 75 Vault 35 1 100 70 ---

18 FL and LW 1 100 75 50 ---

18 U S 2 . ... . .. . .. ..

50 FL and LW 1 100 70 50 ---

50 U S 2 ............

53 FL and LW 1 100 75 50 ---

53 U S 2 ............

-Refer to Figures 4 through 8. FL floor, LW = lower wall and US = upper surfaces.

bScans not performed.

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TABLE 2 SURFACE ACTIVITY LEVELS AUXILIARY BUILDING STRUCTURAL SURFACES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Room! Total Beta Removable Activity Activity Meets Locationa Surfaceb Activity (dpm/100 cm 2) Gross Beta (dpm/100 cm 2)c Alpha Beta DCGLd Vault 30 12 LW 740 1 2 YES 13 FL 4,700 0 -1 YES Vault 31 .. .... _ " ..

9 FL 16,000 0 8 YES 10 FL 4,300 1 1 YES 11 LW 2,600 0 1 YES Vault 34 6 LW 6,000 0 -1 YES 7 FL 6,100 0 7 YES 8 US 260 0 -3 YES Vault 35 1 FL 1,200 1 6 YES 2 FL 4,100 0 -1 YES 3 LW 2,400 0 3 YES 4 US 130 3 2 YES 5 US 170 0 3 YES Room 18 14 Before' FL .110,000 --- f --- NOC

'I 14 After FL 1,100 0 2 YES 15 FL 3,400 1 3 YES 16 FL 4,200 0 6 YES 17 FL 12,000 0 2 YES Room 50 21 FL 12,000 0 5 YES 22 FL 14,000 0 6 YES 23 FL 5,700 0 3 YES 24 FL 10,000 0 8 YES 25 FL 15,000 0 6 YES 26 FL 14,000 0 8 YES Rancho Seco Nuclear Generating Station 1695-SR-02-0 22

TABLE 2 (continued)

SURFACE ACTIVITY LEVELS AUXILIARY BUILDING STRUCTURAL SURFACES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Room 53 _ "__,.________. .

18 FL 5,400 0 4 YES 19 FL 3,700 5 1 YES 20 FL 2,500 3 6 YES aRefer to Figures 3 through 8.

bStructural surfaces; FL = floor, LW = lower wall and US = upper surfaces.

cDirect measurement results rounded to two significant digits.

dDCGL values are provided in Table 5.

cLocation 14 was determined to be a discrete particle that was remediated by SMUD. After remediation, the direct measurement was below the gross beta DCGL.

fSmear sample not collected.

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TABLE 3 AUXILIARY BUILDING ACID WASTE SYSTEM DRAINS AND PIPE PENETRATIONS CONFIRMATORY GAMMA SCAN RANGES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Drain Line Diameter Scan Length Gamma Scan Range (cpm)

Location (inches) (feet) ORISE SMUD Turbine Building Backgroundsa' Conduit, East Side 1 4 1 300 to 600 ___b Conduit, East Side 2 4 1 300 to 600 Conduit, East Side 3 4 1 200 to 600 ---

Conduit, East Side 4 4 1 300 to 600 ---

Penetration, East Side 4 1 300 to 600 ---

Exciter Pad East 4 12 200 to 800 ---

Exciter Pad West 4 12 200 to 800 Background Range ...... _200 to 800 Auxiliary Building Pipe Penetrations' Vault 30 2 to 3 5 400 to 900 NA" Vault 34 2 to 3 5 600 to 1,200 NA Room 18 2 to 14 3 to 5 200 to 800 NA Room 53 2 to 4 2 to 3 200 to 600 NA Auxiliary Building Acid Waste Drainse 4-1-12, Segment 1' 2 0 to 8 400 to 1,400 510 to 19,000 0 900 990 1 600 520 2 800 660 4-2-15 2 3 3,200 7,700 4 5,000 16,000 4.5 20,000 3,000 aTurbine Building embedded piping backgrounds were determined within Turbine Building conduits. This data was collected during a previous ORISE survey (ORISE 2007d).

bMeasurements not performed by SMUD within the Turbine Budding conduits.

cFigure not provided. Each room had numerous pipe penetrations and a portion of those penetrations were scanned.

,Not applicable. ORISE compared the pipe penetration scan results to background.

-Refer to Figures 9 and 10. SMUD data was provided in to ORISE in a preliminary FSS data package. ORISE and SMUD results were rounded to two significant digits.

fSMUD originally numbered incorrectly Acid'Waste Drain Line 4-1-12, Segment I as 4-1-13. Due to discrepancies in the survey data, ORISE recommends further evaluation of this drain line and the instrumentation used to collect the preliminary FSS data.

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TABLE 4 RADIONUCLIDE CONCENTRATIONS IN SOIL SAMPLES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Radionuclide Concentrations in Soil Samples (pCi/g)

Outfall Locationa Co-60 Cs-137 12 0.32 +/- 0 . 0 6 b 34.9 +/- 1.1 13 0.49 + 0.08 47.1 +/- 1.6

'Refer to Figure 11.

bUncertainties represent the 95% confidence level based on total propagated uncertainties.

TABLE 5 DERIVED CONCENTRATION GUIDELINE LEVELS AND ELEVATED MEASUREMENT COMPARISONS FOR SURVEYED ROOMS IN THE AUXILIARY BUILDING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Auxiliary Building Class Gross Beta DCGLb Design DCGLEMCC Survey Unit/Rooma C (dpm/100 cm 2) (dpm/100 cm 2)

Vault 30 1 43,000 163,400 Vault 31 1 43,000 163,400 Vault 34 1 43,000 154,800 Vault 35 1 43,000 154,800 18 FL and LW 1 43,000 137,600 18 US 2 43,000 NAd 50 FL and LW 1 43,000 206,400 50 US 2 43,000 NA 53 FL and LW 1 43,000 172,000 53 US 2 43,000 NA RRefer to Figures 3 through 8. FL = floor, LW lower wall and US = upper surfaces.

bGross beta DCGL accounts for radionuclide fractions and hard to detects as specified in the DTBD-05-15.

cDCGLENic provided by SMUD and accounted for area factors determined for each specific survey unit.

dDCGLiH. 1 c not required for Class 2 survey units.

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TABLE 6 DERIVED CONCENTRATION GUIDELINE LEVELS FOR SOIL SAMPLES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Single Nuclide DCGLw Values for Detectable Radionuclidesa Radionuclide f Peak of the Mean Dose (mrem/y per pCi/g)

DCGLw (Ci/g)

C-14 2.93E-06 8.33E+06 Co-60 1.93E+00 1.26E+01 Ni-63 1.60E-06 1.52E+07 Sr-90 3.76E-03 6.49E+03 Cs-134 1.09E+00 2.24E+01 Cs-137 4.62E-01 5.28E+01 aTable 6-5 from the License Termination Plan (SMUD 2006a).

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REFERENCES Oak Ridge Associated Universities (ORAU). Quality Program Manual for the Independent Environmental Assessment and Verification Program. Oak Ridge, Tennessee; March 1, 2007.

Oak Ridge Institute for Science and Education(ORISE). Final Confirmatory Survey Plan for the Remaining Structural Surfaces, Embedded Piping, Standing Water and Open Land Area Survey Units, Rancho Seco Nuclear Generating Station, Herald California Docket No. 50-312; RFTA No.

06-003]. Oak Ridge, Tennessee; August 10, 2007a.

Oak Ridge Institute for Science and Education. Survey Procedures Manual for the Independent Environmental Assessment and Verification Program. Oak Ridge, Tennessee; August 3, 2007b.

Oak Ridge Institute for Science and Education. Laboratory Procedures Manual for the Environmental Survey and Site Assessment Program. Oak Ridge, Tennessee; June 15, 2007c.

Oak Ridge Institute for Science and Education. Revised-Confirmatory Survey Report for Portions of the Auxiliary Building Structural Surfaces and Turbine Building Embedded Piping, Rancho Seco Nuclear Generating Station, Herald, California. DCN 1695-SR-01-1. Oak Ridge, Tennessee; December 21, 2007d.

Sacramento Municipal Utility District (SMUD). License Termination Plan, Rancho Seco Nuclear Generating Station, Herald, California; April 2006a.

Sacramento Municipal Utility District. Decommissioning Technical Basis Document: Structure Nucide Fraction and DCGLs. DTBD-05-015, Revision 0. Rancho Seco Nuclear Generating Station, Herald, California; June 2, 2006b.

Sacramento Municipal Utility District. Decommissioning Technical Basis Document: Embedded Piping Scenario and DCGL Determination Basis. DTBD-05-009, Revision No. 1.0. Rancho Seco Nuclear Generating Station, Herald, California; June 1, 2007.

U.S. Nuclear Regulatory Commission (NRC). Letter from J. Hickman (NRC-HQ) to S. Redeker (SMUD);

SUBJECT:

Rancho Seco Nuclear Generating Station - Issuance of Amendment RE:

License Termination Plan (TAC No. J52668). Washington, DC; November 27, 2007.

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