ML073450573
| ML073450573 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/07/2007 |
| From: | Adams W Oak Ridge Institute for Science & Education |
| To: | John Hickman NRC/FSME |
| References | |
| 1695-SR-01-0, RFTA 06-003 | |
| Download: ML073450573 (35) | |
Text
( caR.I S HE OAK RIDGE INSTITUTE FOR SCIENCE AND EDUCATION December 7, 2007 Mr. John Hickman Mail Stop: T-8F5 '
Office of Federal and State Materials and Environmental Management Programs U.S. Nuclear Regulatory Commission 11545 Rockville Pike Rockville, MD 20852
SUBJECT:
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-01-0 (DOCKET NO. 50-312, RFTA NO.06-003)
Dear Mr. Hickman:
The Oak Ridge Institute for Science and Education (ORISE) performed confirmatory survey activities on the Auxiliary Building structural surfaces (Rooms 23 to 25 and Rooms 43 through 49) and Turbine Building embedded piping at the Rancho Seco Nuclear Generating Station in Herald, California on October 15 through 18, 2007. These survey activities were requested and approved by the U.S. Nuclear Regulatory Commission (NRC). Enclosed are the confirmatory survey results documenting these survey activities. The surveys included beta and gamma surface scans and direct measurements for total net beta activity within the Auxiliary Building; embedded piping beta-gamma or gamma scans and gross beta activity measurements xvithin the Turbine Building; and limited gamma scans and the collection of a soil sample adjacent to the Lower Mixing Box in the southeastern corner of the facility.
If you have any questions or comments, please direct them to me at 865.576.0065 or Sarah Roberts at 865.241.8893.
Sincerely, L13 cQ'(F Wadce C. Adams ORISE Health Physicist/Project Leader Survey Projects WCA:km Enclosure c: T. Carter, NRC/FSME/D\VrMEP/DD/SP T-8F5 E. Abelquist, ORISE E. Knox-Davin, NRC/FSiME/TWFN 8A23 S. Roberts, ORISE E. Garcia, NRC/Region IV W. Riley, ORISE E. Bailey, ORISE File 1695 Voice: 865.576.0065 Fax: 865.241.3497 E-mail: Wade.Adams@orau.org F. @6 OMTU ý aggNtUATM @ýM
q CONFIRMATORY SURVEY REPORT FOR PORTIONS OF THE AUXILIARY BUILDING STRUCTURAL SURFACES AND TURBINE BUILDING EMBEDDED PIPING
-RANCHO SECO-NUC-LEAR
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HERALD, CALIFORNIA
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Enviromncntal Management Programs U.S. Nuclear Regulator), Corrmission V
Oak Ridge Institute for Science and Education Approved for public release; further dissemination unlimited.
"fhe Oak Ridge Institutc for Science and Education (ORISE) is a U.S. Department of Energy facility focusing on scientific initiatives to research health risks from occupational hazards, assess environmental cleanup, respond to radiation medical emergencies, support national security and emergency preparedness, and educate the next generation of scientists. ORISE" is managed by Oak Ridge Associated Universities. Established in 1946, ORAU is a consortium of 96 colleges and universities.
NOTICES The opinions expressed herein do not necessarily reflect the opinions of the sponsoring institutions of Oak Ridge Associated Universittes.
This report was prepared as an account of work sponsored by the United States Government. Neither the United States Government nor the U.S. Department of Energy, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe on privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement or recommendation, or favor by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.
CONFIRMATORY SURVEY REPORT FOR PORTIONS OF THE AUXILIARY BUILDING STRUCTURAL SURFACES AND TURBINE BUILDING EMBEDDED PIPING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Prepared by W. C. Adams Oak Ridge Institute for Science and Education Oak Ridge, Tennessee 37831-0017 Prepared for the Office of Federal and State Materials and Environmental Management Programs U.S. Nuclear Regulatory Commission DECEMBER 2007 This report is based on work performed under an Interagency Agreement (NRC Fin. No. F-1008) between the U.S. Nuclear Regulatory Commission and the U.S. Department of Energy. The O~ak Ridge Institute for Science and Education performs complementary work under a contract with the U.S. Department of Energy.
Rincho Seco Nuclear Generating Station 1695-SR-01 -0
CONFIRMATORY SURVEY REPORT FOR PORTIONS OF THE AUXILIARY BUILDING STRUCTURAL SURFACES AND TURBINE BUILDING EMBEDDED PIPING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Prepared by: / c~&& K/'~&-~ Date: /2Lhh 2kY?
W. C. Adams, Project Leader Independent Environmental Assessment and Verification Reviewed by: Date: o'7 S.J. Ro*erts, Survey Projects Manager Independent Enviromiental Assessment and Verification Reviewed by: /A/'46 40 Date: /Z-/2,h7 R. D. Condra,/Labratory Manager Independent Environmental Assessment and Verification Reviewed by: Date: L*L4L" A. T. Payne, Quality Manaker Independent Environmental Assessment and Verification Rancho Seco Nuclear Generating Station 1695-SR-01-0,
CONFIRMATORY SURVEY REPORT FOR PORTIONS OF THE AUXILIARY BUILDING STRUCTURAL SURFACES AND TURBINE BUILDING EMBEDDED PIPING 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 2006a).
RSNGS was a 913-MWe pressurized water reactor (PWR) designed by Bechtel Power Corporation.
The plant incorporated a pressurized water type nuclear steam supply system (NSSS) supplied by Babcock and Wilcox Company; a turbine generator and electrical systems; engineered safety features; radioactive waste systems; fuel handling systems; instrumentation and control systems; the necessary auxiliaries; and structures to house plant systems and other onsite facilities.
Due to a public vote the previous day, on June 7, 1989, RSNGS permanently shut down after approximately 14 years of operation. On August 29, 1989, SMUD formally notified the NRC of the permanent cessation of operations at the RSNGS. SMUD submitted the Post Shutdown Decommissioning Activities Report (PSDAR), in accordance with 10 CFR 50.82 (a) (4), in March 1997. In April 2006, SMUD submitted a license termination plan (LTP) that has yet to be approved by the NRC (SMUD 2006a). 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 Oak Ridge Institute for Science and Education (ORISE) perform confirmatory surveys of structural surfaces in the Auxiliary Building and embedded piping in the Turbine 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 a soil sample adjacent to the Lower Mixing Box in the southeast corner of the site grounds. The confirmatory surveys were performed on October 15 through 18, 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 ORISE Survey Procedures and Quality Program Manuals (ORISE 2007b and ORAU 2007).
ORISE judgmentally selected ten Auxiliary Building rooms (Figures 3 through 12) and twelve Turbine Building embedded pipes (Figures 13 and 14) for confirmatory surveys based upon preliminary FSS results. At the request of the NRC site representative, ORISE performed limited Rancho Seco Nuclear Generating Station 1 OS9-SR-01 -0
radiological surveys of the clay soils adjacent to the Lower Mixing Box in the southeastern portion of the site grounds.
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) 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.
Turbine Building Embedded Piping ORISE performed 100 percent beta-gamma radiation scans of approximately 44 horizontal linear feet of the 4" internal diameter (ID) of Turbine Building Drain (TBD) 3-1-27 embedded pipe using the ORISE-designed GM detector pipe monitor array.
Limited gamma scans were performed in eleven vertical (drop down) 4" inner diameter (ID) embedded pipes and conduits at various locations on the ground level as well as the +40 foot level elevations using a cesium iodide, thallium-activated [CsI(Tl)] gamma scintillation detector coupled to a ratemeter with an audible indicator. ORISE performed surveys in the conduits at the request of the NRC site representative and used the collected data as background gamma scan ranges for embedded piping.
Lower Mixing Box Soil Gamma scans of the clay soils adjacent to the Lower Mixing Box were performed using a NaI(TI) gamma scintillation detector coupled to a ratemeter with an audible indicator.
SURFACE ACTIVITY MEASUREMENTS Auxiliary Building Structural Surfaces Based on beta and gamma surface scan results, direct measurements for beta activity were performed at 57 judgmentally-selected locations on the evaluated structural surfaces which were available for confirmatory survey activities. Direct measurements locations are indicated on Figures 3 through 12.
Surface Activity Data Comparison ORISE performed direct beta measurements at five SMUD direct measurement locations in Room 25 for direct measurement data comparison (Figure 5).
Rancho Seco Nuclear Generating Station 1695-SR-01-0 2
Turbine Building Embedded Piping Direct measurements for beta-gamma activity were performed at 14 locations at approximately 1 meter (3.3 feet) intervals within TBD 3-1-27. The ORISE-designed pipe monitor array was equipped with three GM detectors spaced at 1200 intervals and coupled individually to portable ratemeter-scalers. Measurement data were collected for each individual detector as well as totaled for the array. The location of TBD 3-1-27 is indicated on Figure 13.
ORISE performed gamma scans and recorded the gamma scan range for the remaining embedded piping surveys SOIL SAMPLING Lower Mixing Box At the request of the NRC site representative, ORISE collected a clay soil sample adjacent to the Lower Mixing Box in the southeastern portion of the site grounds.
SAMPLE ANALYSIS AND DATA INTERPRETATION Radiological data and sample media were returned to the ORISE laboratory in Oak Ridge, TN for analysis and interpretation. Radioassays were performed in accordance with the ORISE Laboratory Procedures Manual (ORISE 2007c). The soil sample was analyzed by gamma spectroscopy for the primary radionucides-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). Direct measurements for total surface activity were converted to units of disintegrations per minute per 100 square centimeters (dpm/100 cm 2). Embedded piping scan data were reported in units of counts per minute (cpm).
FINDINGS AND RESULTS SURFACE SCANS Auxiliary Building Structural Surfaces The scan percent coverage and room area classification are provided in Table 1. Beta surface scans determined that localized areas of residual elevated beta-gamma radiation were present on floor, lower wall and upper surfaces within the evaluated survey units. In general, the contamination was limited to small areas that were interspersed throughout the rooms.
Turbine Building Embedded Piping Beta-gamma scans of TBD 3-1-27 did not detect beta-gamma radiation levels in excess of the embedded piping derived concentration guideline levels (DCGLs).
Gamma scans of the drop down 4" embedded pipes on the ground level and +40 level elevations did not detect gamma radiation levels in excess of the detector background as determined in the Turbine Building +40 level elevation east side conduits and Exciter conduits.
Rancho Sect Nuclear Generating Station 3 1695-SR-01-0
Lower Mixing Box Gamma scans of the clay soils adjacent to the Lower Mixing Box did not detect any elevated gamma radiation levels.
SURFACE ACTIVITY LEVELS Auxiliary Building Structural Surfaces Beta surface activity measurements were performed at locations of residual elevated beta-gamma radiation determined during surface scans. Total net beta activity measurements ranged from 5,900 to 240,000 dpm/100 cm 2 . Surface activity level results are presented in Table 2.
Surface Activity Data Comparison ORISE surface activity levels for the comparison data set ranged from 2,000 to 5,000 dpm/100 cm 2; and the SMUD surface activity levels ranged from 2,500 to 4,300 dpm/100 cm2 . The data indicate that ORISE and SMUD surface activity levels collected from approximately the same locations are within 25% of the respective FSS and confirmatory survey values. The surface activity data comparison results are presented in Table 3.
Turbine Building Embedded Piping Gross surface activity levels for TBD 3-1-27 are summarized in Table 4. The gross surface activity levels for each measurement location over the assessed area (168 cm 2) for the pipe monitor array ranged from 4,500 to 6,700 dpm/100 cm 2 . ORISE did not subtract background activity from the gross surface activity due in part to the total activity levels within the pipe being well below the guideline levels.
Gamma scans of the drop down 4" embedded pipes did not detect significant gamma radiation levels in excess of the detector background as determined in Turbine Building conduits. For comparison, the CsI(Tl) detector background range for the conduits along the east side of the +40 level elevation was 200 to 800 cpm and the gamma radiation levels observed within the Turbine Building drains ranged from 200 to 1,600 cpm. The confirmatory gamma scan ranges are provided in Table 5.
SOIL SAMPLE The radionuclide concentrations for the soil sample collected near the mixing box were 0.00 pCi/g for Co-60 and 0.03 pCi/g for Cs-137.
COMPARISON OF SURVEY RESULTS WITH GUIDELINES 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 are pending approval 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). The Rancho Seco Nuclear Generating Station 4 1695-SR-01-0
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 survey units (SU) that were being evaluated.
STRUCTURAL SURFACE ACTIVITY LEVELS SMUD used site-specific supplemental DCGLs for Co-60 and Cs-137 for determining surface release criteria. The applicable surface activity guidelines for the structural surfaces within specific rooms/survey units within the Auxiliary Building are provided in Table 6. These DCGLs were provided in the preliminary FSS data packages for each survey unit that was evaluated and were-derived from the LTP and decommissioning technical basis documents (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 survey units. Twelve of the 57 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 survey unit, SMUD calculated Design and Actual DCGL elevated measurement comparison (DCGIEMc) values which are also provided in Table 6. All confirmatory direct surface activity measurements on the Auxiliary Building structural surfaces in the evaluated SUs were within the site-specific survey unit DCGLFc as provided by SMUD in the preliminary FSS data packages for each SU.
EMBEDDED PIPING 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 (SMUIJD 2007).
Confirmatory survey data for the TBD 3-1-27 were compared with the site-specific DCGL for embedded piping. The results indicated that gross surface activity levels (i.e., assuming all detected activity attributed to ROCs) within the pipe were well below the DCGL. Gamma scans of the other evaluated Turbine Building drains did not detect gamma radiation levels in excess of the detector background.
SOIL SAMPLE Table 6-5 from the LTP provides the single nucide 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 Lower Mixing Box soil sample concentrations were well below the respective single radionuclide DCGLs.
SUMMARY
During the period of October 15 and 18, 2007, ORISE performed confirmatory radiological survey activities which included beta and gamma structural surface scans and beta activity direct 1695-SR-01-0 Rancho Seco Nuclear Generating Station 5
measurements within the Auxiliary Building, beta or gamma scans within Turbine Building embedded piping, beta activity determinations within Turbine Building Drain 3-1-27, and gamma scans and the collection of a soil sample from the clay soils adjacent to the Lower Mixing Box.
Beta and gamma surface scans identified several areas of elevated beta activity on the structural surfaces of the evaluated survey units with the Auxiliary Building. Additional investigation of these locations indicated that the majority of the elevated radiation levels were attributable to localized areas of residual beta-gamma radiation. In general, the contamination was limited to small areas that were interspersed throughout the rooms. Direct measurements were performed at 62 locations of which five locations were for direct measurement data comparison with the licensee's data. Several direct measurements exceeded the site-specific gross beta DCGL but all were within the DCGLFMC criteria. A review of the preliminary FSS data packaged indicated that SMUD personnel had also found the elevated residual radiation levels and had based their FSS data package release for those locations using the determined DCGLEMc values for those SUs. Therefore, the results of the confirmatory survey activities for the evaluated structural surfaces of the Auxiliary Building confirmed the radiological status of the evaluated areas as presented in the licensee's preliminary FSS data packages.
ORISE performed survey data comparisons on five RSNGS direct measurement locations within Auxiliary Building Room 25; the results indicated that SMUD's radiological survey data were consistent and in agreement with ORISE's direct measurement results.
Beta and gamma surface scans of the evaluated Turbine Building drains did not indicate any areas of elevated radiation levels; all scan results and direct measurement results within the embedded piping were less that the applicable DCGL of 100,000 dpm/100 cm 2.
The clay soil sample results from the Lower Mixing Box were below the individual radionuclide DCGLs and meet the soil release criteria.
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Rancho Seco Nuclear Generating Station 6
FIGURES Rancho Seco Nuclear Generating Station 1695-SR-0j-o
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TABLES Rancho Seco Nuclear Generating Station 1695-SR-01-0
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 Beta Beta Beta Survey Floor Floor Lower Wall Upper Wall Unit/Rooma 23 FL and LW 1 50 50 25 --- b 24 1 100 50 50 ---
25 FL and LW 1 100 75 50 ---
25 US 1 ......... 2 43 FL and LW 1 100 50 50 ---
44 1 100 50 50 ---
45 1 100 50 50 5 46 1 100 50 50 10 47 1 100 75 50 ---
48 1 100 50 50 ---
49 1 100 100 100 20 aRefer to Figures 3 through 12. FL = floor, LW = lower wall and US = upper surfaces.
bScans not performed.
Rancho Seco Nuclear Generating Station 23 1695-SR-01-0
TABLE 2 SURFACE ACTIVITY LEVELS AUXILIARY BUILDING STRUCTURAL SURFACES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Room/ Surface b Total Beta Activity Activity
-Meets Gross Activity Meets Design Activity ActualMeets Location' (dpm/100 cm 2)C Beta DCGLd DCGLEMcd DCGLEMCd Room 23 56 FL 240,000 NO NO YES 57 FL 25,000 YES YES YES 58 / FL 51,000 NO YES YES 59 FL 26,000 YES YES YES 60 FL 110,000 NO YES YES 61 LW 190,000 NO NO YES 62 LW 25,000 YES YES YES Room 24 47 FL 44,000 NO YES YES 48 FL 30,000 YES YES YES 49 FL 30,000 YES YES YES 50 FL 28,000 YES YES YES 51 LW 20,000 YES YES YES 52 LW 30,000 YES YES YES 53 LW 37,000 YES YES YES 54 LW 30,000 YES YES YES 55 LW 35,000 YES YES YES Room 25 33' FL 74,000 NO YES YES 34 FL 94,000 NO YES YES 35 FL 18,000 YES YES YES 36 FL 57,000 NO YES YES 37 FL 18,000 YES YES YES 38 FL 32,000 YES YES YES 39 FL 100,000 NO YES YES 40 LW 12,000 YES YES YES 41 US 100,000 NO YES YES Room 43 15 LW 12,000 YES YES YES 16 LW 12,000 YES YES YES 17 LW 17,000 YES YES YES Room 44 18 FL 12,000 YES YES YES 19 LW 20,000 YES YES YES 20 LW 22,000 YES YES YES 21 LW 8,000 YES YES YES 22 LW 11,000 YES YES YES Rancho Seco Nuclear Generating Station 1695-SR-01-0 24
TABLE 2 (continued)
SURFACE ACTIVITY LEVELS AUXILIARY BUILDING STRUCTURAL SURFACES RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Total Beta Activity Activity Meets Activity Meets Rotom/a Surfaceb Activity Meets Gross Design Actual
______n (dpm/100 cm 2)c Beta DCGLd DCGLEMCd DCGLEMCd Roomn 45 23 US 39,000 YES YES YES 24 US 23,000 YES YES YES 25 US 30,000 YES YES YES 26 US 5,900 YES YES YES 27 US 14,000 YES YES YES 28 FL 36,000 YES YES YES 29 LW 33,000 YES YES YES 30 FL 46,000 NO YES YES 31 FL 22,000 YES YES YES 32 US 13,000 YES YES YES Roomn-46 5 FL 24,000 YES YES YES 6 LW 38,000 YES YES YES 7 FL -36,000 YES YES YES 8 LW 12,000 YES YES YES 9 FL 47,000 NO YES YES 10 LW 31,000 YES YES YES 11 LW. 34,000 YES YES YES Room 471' ___ _ - "_ _ _ _....
1 LW 37,000 YES YES YES 2 FL 26,000 YES YES YES 3 LW 16,000 YES YES YES 4 LW 21,000 YES YES YES Room 48' 12 FL 9,900, YES YES YES 28 FL 8,700 YES YES YES Room 49,9Co-60 14 LW 12,000 YES YES YES
-Refer to Figures 3 through 12.
bStrucmral surfaces; FL = floor, LW = lower wall and US upper surfaces.
cDirect measurement results rounded to two significant digits.
dDCGL values are provided in Table 6.
Rancho Seco Nuclear Generating Station 1695-SR-01-0 25
TABLE 3 SURFACE ACTIVITY DATA COMPARISON AUXILIARY BUILDING ROOM 25 RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA o bTotal Beta Activity Surface" (dpm/100 cm 2)
ORISE SMUD ORISE SMUDc 42 02BD FL 4,200 4,000 43 01BD FL 3,500 3,700 44 05BD FL 2,000 2,500 45 19BD FL 4,400 4,300 46 04BD FL 5,000 4,200
-Refer to Figure 5. SMUD measurement locations were provided in the preliminary FSS data by SMUD.
bFL = floor.
CSMUD Total Beta Activity results were provided by SMUD. ORISE and SMUD Total Beta Activity results were rounded to two significant digits.
Rancho Seco Nuclear Generating Station 1695-SR-01-0 26
TABLE 4 TURBINE BUILDING EMBEDDED PIPING CONFIRMATORY SURVEY RESULTS FOR TBD-3-1-27 RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA TBD 3-1-27' Gross Total Beta/Gamma Activity Pipe Position (feet) (dpm/100 cm 2)b',
3.3 6,700 6.6 5,900 9.8- 6,600 13.1 6,100 16.4 5,200 19.7 6,300 23.0 5,500 26.2 5,000 29.5 5,200 32.8 5,200 36.1 .5,700 39.4 4,500 42.7 5,400 44.3 6,300
ýRefer to Figure 13.
bBackground was not subtracted. ORISE Total Activity results were rounded to two significant digits.
cThe embedded piping DCGL is 100,000 dpm/100 cm 2 with a grouting action level of 21,000 dpm/100 cm 2 . ORISE pipe detector was calibrated with a Tc-99 flexible source. Although the pipes had both Co-60 and Cs-137, ORISE took a conservative approach and considered that all the contamination within the pipe was from Co-60 and used a source efficiency of 0.25 Rancho Seco Nuclear Generating Station 27 1695-SR-01-0
TABLE 5 TURBINE BUILDING EMBEDDED PIPING CONFIRMATORY GAMMA SCAN RANGES FOR REMAINING EMBEDDED PIPING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA ORISE Turbine Drain Building Line' Diameter (inches) Scan Depth (feet) Gamma Scan Range (cpm)
Turbine Building Backgrounds" Conduit, East Side 1 4 1 300 to 600 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 Turbine Building Ground Level Drains TBD 6-3-11 4 8 300 to 1600 TBD 4-2-7 4 13 200 to 600 TBD 3-2-01 4 13 500 to 1600 TBD 3-2-4 4 10 200 to 800 TBD 3-1-7 4 10 200 to 600 TBD 3-1-4 4 13 200 to 800 Turbine Building +40 Level Drains TBD 1-2-28 4 1 250 to 450.
TBD 1-2-23 4 1 220 to 450 TBD 1-2-26 4 11 200 to 1000 TBD 1-2-24 4 13 400 to 900 TBD 1-2-20 4 13 200 to 1000
'Refer to Figures 13 and 14.
bTurbine Building embedded piping backgrounds were determined within Turbine Building conduits.
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TABLE 6 DERIVED CONCENTRATION GUIDELINE LEVELS AND ELEVATED MEASUREMENT COMPARISONS FOR SURVEYED ROOMS IN THE AUXILIARY BUILDING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Auxiliary Gross Beta Design Actual Building Survey Class DCGLb DCGLEMcC DCGLEMcc Unit/Rooma (dpm/100 cm 2) (dpm/100 cm 2) (dpm/100 cm 2) 23 FL and LW 1 43,000 150,500 6.4E7 24 1 43,000 150,500 N/Ad 25 FL and LW 1 43,000 146,200 N/A 25 US 1 43,000 141,900 N/A 43 FL and LW 1 43,000 137,600 N/A 44 1 43,000 141,900 N/A 45 1 43,000 141,900 1.11E6 46 1 43,000 141,900 N/A 47 1 43,000 141,900 N/A 48 1 43,000 193,500 N/A 49' 1 16,000W 142,400 N/A
-Refer to Figures 3 through 12. 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.
cDCGLEMC provided by SMUD and accounted for area factors determined for each specific survey unit.
dDue to SMUD FSS findings, Actual DCGLEMc was not applicable for these survey units, since all results were less than the gross beta DCGL.
cThe major contaminant for Room 49 was determined to be Co-60; SMUD accounted for ROCs by calculating an appropriate gross beta DCGL (based on ROC fractions in relation to Co-60) for this room.
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REFERENCES Oak Ridge Associated Universities (ORAU). Quality Program Manual for th%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.
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 Nuclide 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.
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