ML091350468

From kanterella
Jump to navigation Jump to search
Confirmatory Survey Report for the Rancho Seco Nuclear Generating Station Containment Building by Oak Ridge Institute for Science and Education (Orise)
ML091350468
Person / Time
Site: Rancho Seco
Issue date: 05/06/2009
From: Adams W
Oak Ridge Institute for Science & Education
To: John Hickman
NRC/FSME
References
DCN 1695-SR-05-0, RFTA 06-003
Download: ML091350468 (54)
v • d • e


Text

3 RI S OAK RIDGE INSTITUTE FOR SCIENCE AND EDUCATION Mr. John Hickian Mvajil Stop: ýT-,8F54 OffiCC of Federal and State Materifals and Enviio6mntal Mangiemnt Programs.

U-S.,XNuc]e&ar Regulatorey Coihii ,issio-n

°11545 Rockville Pike RocK-vllc', IMD 2805r2

SUBJECT:

iY CONFIRMATORYSURVEY REPORT, FO.RACT.iVITIES PERFORMED IN THECONTAINMENTBUILDING RANCHO SECO NUCLEAR GENERATINGSTATION HERALD, CALIFORNIA DCN.1695-SR-05,0 (DOCKET NO. 50-312, RT T*NO.06-003)

D ear -Mr.fl l-Iii;kmain:

Thei.Oak jge .t Institute for.id~encfn..Educadon'(ORlýSE) perIformed confirmatory_ sureyacti itics on strictiural's'urfaces in ihe ConQtiihhnent-.iBuildinig at-.ýhRaxticho SccoNuclcar GdcneriratngS.Staiion in lerald, California-ona Decembefr9 thrbu6gh 11L 2008 and iMarid.10; 2009, These. sii-vey aictivitles were requested anr4approved by the U.S. Nuclear Rcgulatory*Commission (NRC) Enclosed is'the final reprtr that summarizes I0USE's survey procedires and&resultws iofrheco.nfirmatory* sunreys: The surveysý iticluded beta andgamma surfaiice sc~in ditect mieastuirermi*entsý for total net beta activity, and smears for remoable alpi'a ind beta ,civit:

If you have avi, l uonS,'pkasc direct theim t6 me"at. 865.576,0065 or Tim' Vitkus at 865.576.'073.

S~incer 'ely, XXiade C. tdaIn'sf ORISE -1 alth Plhysicist/Proj'ect Leader Independent Environmental Assessment and Verification WCA~bf En tosureý c: T; Carter, NR(i/FSME/D MEP/DD/SP 8F5 E. Abilqu'ist, ORI"SE",

T. Pattersbii, NRC/FSME/,1*VFN 8A23 S. RobeirtsORISE T: Youngblkod, NRC/FSME/DWMEi//TVFN 8 F5 T1'. itkus, ORISE R. Evans,, NRC/Regioni - File1695.

Voice: 865.576.0065 Fax: 865.241'3497 E-mnail-: W\adceAdains(orauiorg

CONFIRMATORY SURVEY REPORT FOR ACTIVITIES PERFORMED IN THE CONTAINMENT BUILDING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA

!" I * ...... ......

i.....I............

W C L Adax *..--* --~--~--~---.-

i[ . . . . ..

47 7- ! JII Office ofI'Ieder 1al__de r Ii ivronmentahialagci igntnI Po,'ims

~U NUILw Rgu ~~rxC67in-i,-i5';ion-

' i p

o!r: "1 9

p

$~

II

-~

p -- ~o--o

___iLK>

(a)MUia Oak- Ridge Institute for Science and Education C5 Approved for public release; further dissemination unlimited.

The Oak Ridge Institute 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 99 colleges and universities.

NOTICES The opinions expressed herein do not necessarily reflect the opinions of the sponsoring institutions of Oak Ridge Associated Universities.

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.

CONFIRMATORYSURVEY REPORT FOR ACTIVITIES PERFORMED IN THE CONTAINMENT BUILDING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA Prepared by W. C. Adams ORISE Prepared for the U.S. Nuclear Regulatory Commission FINAL REPORT May 2009 This report is based on work performed by the Oak Ridge Institute for Science and Education under contract number DE-AC05-06OR23100 with the Department of Energy.

Prepared by the Oak Ridge Institute for Science and Education, under interagency agreement (NRC FIN No. J1008) between the U.S. Nuclear Regulatory Commission and the U.S. Department of Energy.

Rancho Seco Nuclear Generating Station 169S-SR-05-0

CONFIRMATORY StJRVEY REPORT FOR ACTIVITIES PERFORMED IN THE CONTAINMENT BUILDING; RANCHO SECo NUCLEAR GENERATING STATION HERALD, CALIFORNIA Prepared by: Datcý: ~L~ 12 W. C. A dams. Project .1,ader IndCpendnt Asns-ironmentiAss cssmcnt and Verification cvie ecd by: Datc: ý9vj I ndep[ent/.e-nvironmciintal Assessnient and Verification Reviewcd by: Date: -.0 R. D. Condra, Laboratory Managcr Inndpdendn Pnivironnteiital' Issment ard Verificition Reviewed by: Date: S1,19 A.T.,Paynej, Quahity ManlagII Independent Environniental Assessment and Verification+

Reviewed by:

S.. Robcrts, Associate Director IDateý: 35 / O-Jc

'Independent l-nvironmental Assessimnt and Viýrificaion Rincho Sitci Nuckcar ("emniting,.tunon I(9~RO4

  • 1695-SRZ-05-0

ACKNOWLEDGMENTS The author would like to acknowledge the significant contributions of the following staff members:

FIELD STAFF T. D. Herrera LABORATORY STAFF R. D. Condra J. S. Cox W. P. Ivey W. F. Smith CLERICAL STAFF R. M. Fink K. M. Moore A. Ramsey ILLUSTRATORS T. L. Brown K. M. Moore Rancho Seco Nuclear Generating Station 1695-SR-05-0

TABLE OF CONTENTS PAGE List of Figures ..................................................................................................................................................... ii Iist of Tables ..................................................................................................................................................... iii A bbreviations and A cronym s.......................................................................................................................... iv Introduction and Site History .......................................................................................................................... 1 Site D escription .................................................................................................................................................. 2 Objective ............................................................................................................................................................. 2 D ocum ent R eview ............................................................................................................................................. 3 Confirm atory Survey Procedures ........................................................................................................... 3 Reference System ........................................................................................................................................... 4 Surface Scans .................................................................................................................................................. 4 Surface A ctivity M easurem ents ........................................................................................................... 5 Sam ple A nalysis and D ata Interpretation .................................................................................................. 5 Findings and Results ..................................................................................................................................... 6 D ocum ent Review ......................................................................................................................................... 6 Surface Scans .................................................................................................................................................. 6 Surface A ctivity Levels ................................................................................................................................. 6 Com parison of Results With Site Release Criteria .................................................................................. 7 Conclusion .......................................................................................................................................................... 7 References ........................................................................................................................................................... 9 Appendices:

Appendix A: Figures Appendix B: Tables Appendix C: Major Instrumentation Appendix D: Survey and Analytical Procedures Rancho Seco Nuclear Generating Station i 1695-SR-05-0

LIST OF FIGURES PAGE Figure A-1: Location of Rancho Seco Nuclear Generating Station, Herald, California ............... A-1 Figure A-2: Plot Plan of the Industrial Area at Rancho Seco Nuclear Generating Station ............... A-2 Figure A-3: Survey Unit F8110111, 75 to 115 Feet Elevation ............................................................... A-3 Figure A-4: Survey Unit F8110111 - Direct Measurement Locations ................................................. A-4 Figure A-5: Survey Unit F8110112, 25 to 75 Feet Elevation ........................................................... A-5 Figure A-6: Survey Unit F8110112 - Direct Measurement Locations ................................................. A-6 Figure A-7: Survey Unit F8110113, -27 to 25 Feet Elevation ................................................................ A-7 Figure A-8: Survey Unit F8110113 - Direct Measurement Locations ................................................. A-8 Figure A-9: Survey Unit F8110114, Floor - Direct Measurement Locations ...................................... A-9 Figure A-10: Survey Unit F8110114, B Sump - Direct Measurement Locations ....................... A-10 Figure A-11: Survey Unit F8110114, Emergency Sump - Direct Measurement Locations ............ A-11 Rancho Seco Nuclear Generating Station ii 1695-SR-05-0

LIST OF TABLES PAGE Table 1: ORISE Confirmatory Survey Areas ............................................................................................ 4 Table -B-1: Derived Concentration Guideline Levels and Elevated Measurement Comparisons for the C ontainm ent Building ............................................................................................ B -1 Table B-2: Survey Unit Classification and Scan Coverage ....................................................................... B-2 Table B -3: Surface A ctivity L evels .............................................................................................................. B -3 Rancho Seco Nuclear Generating Station iii 1695-SR-05-0

ABBREVIATIONS AND ACRONYMS bi number of background counts in the interval d' index of sensitivity S. instrument efficiency surface efficiency Etotal total efficiency BKG background C-14 carbon- 14 cm centimeter 2

cm square centimeter Co-60 cobalt-60 COC contaminants of concern cpm counts per minute Cs-137 cesium-137 DCGL derived concentration guideline level DCGLEMc DCGL elevated measurement comparison DP decommissioning plan dpm/100 cm 2 disintegrations per minute per 100 square centimeters DQOs data quality objectives DTBD decommissioning technical basis document FSS final status survey FSSP final status survey plan FSSR final status survey report IEAV Independent Environmental Assessment and Verification ISFSI independent spent fuel storage installation ISM Integrated Safety Management ITP Intercomparison Testing Program JHA job hazard analysis keV kiloelectron volts LTP license termination plan 2

m square meters mg milligram MAPEP Mixed Analyte Performance Evaluation Program MARSSIM Multi-Agency Radiation Survey and Site Assessment Manual MDC minimum detectable concentration MDCR minimum detectable count rate MeV million electron volts mrem/yr millirem per year MWe megawatt electric NaI(TI) sodium iodide (thallium-activated)

NIST National Institute of Standards and Technology NRC U.S. Nuclear Regulatory Commission NRIP NIST Radiochemistry Intercomparison Program ORAU Oak Ridge Associated Universities ORISE Oak Ridge Institute for Science and Education Rancho Seco Nuclear Generating Station iv 1695-SR-05-0

ABBREVIATIONS AND ACRONYMS (continued)

PDQ potential deviation from quality PSDAR Post Shutdown Decommissioning Activities Report PWR pressurized water reactor RSNGS Rancho Seco Nuclear Generating Station s second SMUD Sacramento Municipal Utility District SU survey unit Sr/Y-90 strontium/yttrium-90 SRC site release criteria TcL-99 technetium-99 TEDE total effective dose equivalent T1 -204 thallium-204 Rancho Seco Nuclear Generating Station V 1695-SR-05-0

CONFIRMATORY SURVEY REPORT FOR ACTIVITIES PERFORMED IN THE CONTAINMENT BUILDING RANCHO SECO NUCLEAR GENERATING STATION HERALD, CALIFORNIA INTRODUCTION AND SITE HISTORY 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. RSNGS was a 913-megawatt electric (MWe) pressurized water reactor (PWR) designed by Bechtel Power Corporation. The plant incorporated a pressurized water type nuclear steam supply system 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 U.S.

Nuclear Regulatory Commission (NRC) of the permanent cessation of operations at the RSNGS.

In May 1991, SMUD submitted the Rancho Seco Decommissioning Plan (DP), which was approved by the NRC in March 1995. SMUD submitted the Post Shutdown Decommissioning Activities Report (PSDAR), in accordance with 10CFR50.82 (a) (4), in March 1997. SMUD began decommissioning activities in February 1997 and completed transfer of all the spent nuclear fuel in August 2002.

In April 2006, SMUD submitted a license termination plan (LTP) that the NRC approved on November 26, 2007 (SMUD 2006a and NRC 2007). SMUD has completed decontamination efforts and final status surveys (FSS) on the remaining structural surfaces and in open land areas. The major contaminants of concern (COC) identified by SMUD at RSNGS were beta-gamma emitters-fission and activation products-resulting from reactor operation. Cesium-137 (Cs-137) and cobalt-60 (Co-60) were identified during characterization as the predominant radionuclides present on structural surfaces.

Rancho Seco Nuclear Generating Station 1695-SR-05-0

The NRC's Headquarters and Region IV Offices requested that the Oak Ridge Institute for Science and Education (ORISE) perform confirmatory surveys of structural surface survey units (SU) in the Containment Building at the RSNGS (Figures A-1 and A-2). The confirmatory surveys were performed during the period of December 9 through 11, 2008 and March 10, 2009.

SITE DESCRIPTION The RSNGS is located in the southeast part of Sacramento County, California and is approximately 26 miles northeast of Stockton and 25 miles southeast of Sacramento. The site lies between the Sierra Nevadas to the east and the Pacific Coast Range bordering the Pacific Ocean to the west in an area of flat to slightly rolling terrain at an elevation of approximately 200 feet above mean sea level.

The land surrounding the site is used almost entirely for agricultural purposes, as grazing land, and for grape production. The owner-controlled site is approximately 2,500 acres with all acreage being owned by SMUD. An 87-acre fence-enclosed Industrial Area (Figure A-2) containing the nuclear facility is within the owner-controlled area. Approximately 0.5 miles south of the Industrial Area boundary is a 30-acre gas-fired power plant. The site also contains the 560-acre Rancho Seco Reservoir and Recreation Area, a 50-acre solar powered electrical generating station, and a 10-acre independent spent fuel storage installation (ISFSI).

The RSNGS design included several structures that were engineered and constructed to contain radioactive material. These structures were located within the Industrial Area boundaries and included the Auxiliary Building, the Containment/Reactor Building, the Spent Fuel Building, the Fuel Storage Building, the Turbine Building, the Cooling Towers and structures containing tanks for storage of radioactive liquids. The site also included ancillary facilities that were used to support normal plant operations. These facilities consisted of warehouses, water and sewage treatment plants, and administrative office buildings.

OBJECTIVE The objective of the confirmatory survey was to generate independent radiological data for use by the NRC in evaluating the adequacy and accuracy of the licensee's FSS results.

Rancho Seco Nuclear Generating Station 2 1695-SR-05-0

DOCUMENT REVIEW ORISE reviewed the licensee's preliminary final radiological survey data for adequacy and appropriateness, taking into account data quality objectives (DQOs) contained in the LTP (SMUD 2006a). ORISE also reviewed and evaluated final status survey plans (FSSP) and final status survey reports (FSSR) in accordance with the ORISE site-specific survey plan to ensure that FSS procedures and results adequately met site LTP commitments and Multi-Agengy Radialion Survey and Site Investigation Manual (MARSSIM) considerations (ORISE 2007a, SMUD 2006a and NRC 2000).

CONFIRMATORY SURVEY PROCEDURES To expedite the confirmatory survey process, ORISE coordinated and worked with the NRC site representative to conduct confirmatory surveys as the licensee provided preliminary FSS survey data.

This provided the NRC the quality assurance metric that the site's reported radiological status satisfied the site license termination criteria. ORISE survey activities were performed in a manner that addressed the confirmatory objective listed above. ORISE performed confirmatory survey activities in judgmentally selected survey units on the RSNGS site. These confirmatory survey activities assessed whether remediation activities met the DQOs for unrestricted release.

In December 2008 and March 2009, ORISE conducted radiological confirmatory survey activities of the RSNGS structural surfaces within the Containment Building. Confirmatory surveys included beta and gamma surface scans, direct measurements for total net beta activity, and smears for removable alpha and beta activity. Locations of elevated direct radiation that potentially exceeded the derived concentration guideline levels (DCGLs) were marked for further investigation.

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 followed the guidance provided in the ORISE Survey Procedures and Quality Program Manuals (ORISE 2008a and ORAU 2007).

Based on the preliminary FSS data results, ORISE judgmentally selected several survey grids which exhibited elevated beta activity readings during confirmatory surveys. These survey grids were combined with randomly selected survey grids so that a minimum of nine (five percent) of the survey unit grids for each of the Containment Building wall survey units would receive confirmatory Rancho Seco Nuclear Generating Station I I6Q9;-1R-0q-0

surveys. ORISE performed confirmatory surveys on up to 50% of the floor and sump surfaces.

Confirmatory survey activities on structural surfaces were performed within the following survey units and grid blocks of the Containment Building:

ORS COFRMTR SURVE AREAS Survey Unit Survey Grids , Figures Survey Grids M0049, M0053, F8110111, Reactor M0065, M0068, M0073, Containment, 75 to 115 feet M0128, M0129, M0135, and A-3 through A-4 M0138 Survey Grids M0006, M001 1, F8110112, Reactor M0012, M0022, M0023, Containment, 25 to 75 feet M0027, M0056, M0124, and M01 67 Survey Grids M001 1, M0027, F8110113, Reactor M0028, M0051, M0063, Containment, -27 to 25 feet M0099, M0110, M0122, M0170 and M0171 F8110114, Reactor Containment, Floor and SumpsFloor, B Sump and Emergency A-9 through A-11

(-27 foot elevation) Sump REFERENCE SYSTEM Measurements and sampling locations were referenced to the existing RSNGS grid system and/or on RSNGS provided figures.

SURFACE SCANS Surface scans for beta and gamma radiation were performed on structural surfaces that could be safely accessed. Scan coverage percentage was based upon the SU classification and increased or decreased depending on findings as the survey progressed and project time constraints. Scans for gamma and beta radiation were performed using sodium iodide, thallium-activated [NaI(Tl)]

scintillation and gas proportional detectors. Particular attention was given to cracks and joints in the surfaces, exposed concrete surfaces, and other locations where material may have accumulated.

Locations of elevated direct radiation, suggesting the presence of residual contamination, were marked and identified for judgmental measurements. All detectors were coupled to ratemeters or ratemeter-scalers with audible indicators.

Rancho Seco Nuclear Generating Station 4 1695-SR-05-0

SURFACE ACTIVITY MEASUREMENTS With a few exceptions, direct measurements for total beta activity were performed at five judgmentally-selected locations within each survey grid where residual contamination, identified by surface scans, exhibited radiation levels above background levels and potentially above acceptable unrestricted release limits established for the site.

Based on beta and gamma surface scan results, direct measurements for beta activity were performed at 157 judgmentally-selected locations on the evaluated structural surfaces within the Containment Building wall and floor surfaces. Direct measurements were performed using hand-held gas proportional detectors coupled to ratemeters-scalers. Dry smears, for determining removable gross alpha and beta activity, were collected from each direct measurement location on the floor and at the location that exhibited the maximum static beta activity within each survey grid on the wall surfaces. Direct measurement and smear locations are indicated on Figures A-3 through A-11.

SAMPLE ANALYSIS AND DATA INTERPRETATION Samples and data were returned to the ORISE laboratory in Oak Ridge, Tennessee for analysis and interpretation. Samples were analyzed in accordance with the ORISE Laboratory Procedures Manual (ORISE 2008b). Smears were analyzed for gross alpha and gross beta activity using a low-background 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). The data generated were compared with the licensee's gross beta and design DCGLs for each specific SU where confirmatory surveys were performed (Table B-I).

The primary COCs for the RSNGS are beta-gamma emitters-fission and activation products-resulting from reactor operation. Cesium-137 and Co-60 were identified by SMUD during characterization as the predominant radionuclides present on structural surfaces and in the soils. SMUD developed site-specific DCGLs, which were approved by the NRC, based on dose modeling to future occupants not to exceed 25 millirem per year (mrem/yr) total effective dose equivalent (TEDE) as presented in Section 6 of the LTP (SMUD 2006a and NRC 2007). The structural surface DCGL's were modified by SMUD to reflect the ratio of radionuclide concentrations (account for the presence of unmeasured contaminants based on contaminant ratios)

Rancho Seco Nuclear Generating Station 5 1695-SR-05-0

in the specific SUs that were being evaluated. The DCGL's for the evaluated structural surfaces (refer to Table B-I) for these confirmatory surveys 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).

Additional information regarding instrumentation and procedures may be found in Appendices C and D.

FINDINGS AND RESULTS The results for the confirmatory surveys are provided below.

DOCUMENT REVIEW ORISE's review of SMUD's preliminary FSS data packages indicated that the procedures and methods implemented for the FSS were appropriate and that the resultant data were acceptable.

SURFACE SCANS Beta and gamma surface scans, in the Containment Building, identified several areas of elevated beta and gamma radiation on the floor and walls within the evaluated SUs. With one exception, these locations were localized areas (<300 cm 2) of residual fixed contamination. The one exception was a discrete particle that was discovered in SU F8110114 in the Emergency Sump at location 1. NRC and SMUD personnel were immediately notified. The survey unit classifications and scan percent coverage are provided in Table B-2.

SURFACE ACTIVITY LEVELS Total beta activity measurements ranged from -76 to 180,000 dpm/100 cm 2 . Residual surface activity levels approaching and exceeding the site-specific gross beta DCGL but less than the SU specific design DCGL elevated measurement comparison (DCGLEMc) were limited to small areas that were interspersed throughout the SUs. Prior to the removal of the discrete particle, the beta activity was measured at 130,000 dpm/1OOcm 2; after removal by SMUD, the beta activity was 2,500 dpm/1OOcm 2. Removable gross alpha and gross beta activity ranged from 0 to 170 and -4 to 3,400 dpm/100 cm 2, respectively. Surface activity measurements are documented in Table B-3.

Rancho Seco Nuclear Generating Station 6 1695-SR-05-0

COMPARISON OF RESULTS WITH SITE RELEASE CRITERIA Confirmatory survey data for structural surfaces were compared with the structural site-specific DCGL for the evaluated SUs. Fifteen of the 157 direct beta activity measurement results on the survey units had structural surface activity levels that 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 DCGLIMc values which are also provided in Table B-1. All 15 of the confirmatory survey measurement locations, including the previously discussed discrete particle, were less than 300 cm 2 . After the removal of the discrete particle, all confirmatory direct surface activity measurements on the structural surfaces in the evaluated SUs were within the site-specific SU DCGLFNIc as provided by SMUD in the preliminary FSS data packages.

CONCLUSION During the period of December 9 through 11, 2008 and March 10, 2009, 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 Containment Building.

Beta and gamma surface scans identified several areas of elevated beta radiation on the structural surfaces of the evaluated SUs. Additional investigations of these locations indicated that the majority of the elevated radiation levels were attributable to localized areas of residual beta-gamma radiation within the matrix of the concrete and/or metal media. In general, the elevated surface activity was limited to small areas (less than 300 cm 2) that were interspersed throughout the walls and floor. Direct measurements were performed at 157 locations. Fifteen direct measurements exceeded the site-specific gross beta DCGL but all were within the SU specific design DCGLEMc criteria. One of the 15 measurement locations was determined to be a discrete particle and was remediated by SMUD personnel. SMUD's investigation of the finding is documented in a potential deviation from quality form (PDQ #08-021). In an email dated March 25, 2009', the NRC I Electronic mail from J. Hickman (NRC-HQ) to E. Ronningen (SMUD).

Subject:

Discrete Particle Issues. March 25, 2009.

Rancho Seco Nuclear Generating Station 7 1695-SR-05-0

requested that SMUD perform an evaluation of the significance of the discrete particles found by ORISE and that SMUD personnel perform a gamma walkover resurvey of the transport routes and all outdoor Class 1 areas.

The final confirmatory survey results for the evaluated SUs are in agreement with the radiological status of these SUs as presented in the licensee's preliminary FSS data packages.

Rancho Seco Nuclear Generating Station 8 1595-SR-05-0

REFERENCES Oak Ridge Associated Universities (ORAU). Quality Program Manual for the Independent Environmental Assessment and Verification Program. Oak. Ridge, Tennessee; November 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; May 1, 2008a.

Oak Ridge Institute for Science and Education. Laboratory Procedures Manual for the Independent Environmental Assessment and Verification Program. Oak Ridge, Tennessee; December 5, 2008b.

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.

U.S. Nuclear Regulatory Commission (NRC). Mulfi-Ageng Radialion Survey and Site Invesligalion Manual (MARSSIM), NUREG-1 575; Revision 1. Washington, DC; August 2000.

U.S. Nuclear Regulatory Commission. 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.

Rancho Sect Nuclear Generating Station 9 1695-SR-05-0

APPENDIX A FIGURES Rancho Seco Nuclear Generating Station 1695-SR-05-0

N NOT TO SCALE Figure A-i: Location of Rancho Seco Nuclear Generating Station, Herald, California Rancho Seco Nuclear Generating Station A-1 1695-SR-05-0

SPRAY PONDS

,/

BUILDING CHLORINE BIDN ISFSI WATER TREATMENT PLANT SEWAGE TREATMENT ARE SWITCHYARD AUX1LIARI BUILDING ADMINISTRATION BUILDING T & R BUILDING N

NOT TO SCALE Figure A-2: Plot Plan of the Industrial Area at Rancho Seco Nuclear Generating Station Rancho Seco Nuclear Generating Station A-2 1695-SR-05-0

a a a - a a - - a U - a a a -

¶ 1~.

li

~>II ~*

2 twO

  • 5 a,

I ,

O Surveyed Grids Figure provided by SMUD Figure A-3: Survey Unit F8110111, 75 to 115 Feet Elevation Rancho Seco Nuclear Generating Station A-3 1695-SR-05-0

GRID 49 GRID 53 GRID 65 GRID 68 GRID 73 GRID 128 GRID 129 GRID 135 GRID 138 MEASUREMENT/SAMPLE 0 5 LOCATION " _

  1. SINGLE POINT SCALE (in meters)

Figure A-4: Survey Unit F8110111 - Direct Measurement Locations Rancho Seco Nuclear Generating Station A-4 1695-SR-05-0

IC Ww" t

Vsim x P ANN-X a Aga en,

-o I,

"Im N

I, IM3 7 7; C4, No C4 ii N0M n m O Surveyed Grids Figure provided by SMUD Figure A-5: Survey Unit F8110112, 25 to 75 Feet Elevation Rancho Seco Nuclear Generating Station 1695-SR-05-0

GRID 6 GRID 11 GRID 12 GRID 22 GRID 23 GRID 27 GRID 56 GRID 124 GRID 167 MEASUREMENT/SAMPLE 0 5 LOCATION ,_ _ _

  1. SINGLE POINT SCALE (in meters)

Figure A-6: Survey Unit F8110112 - Direct Measurement Locations Rancho Seco Nuclear Generating Station A-6 1695-SR-05-0

JLfL WOiN

'Mý

.3 aODM tom 0*

'-3 1'

-3 tom N -

.9

-I= I-.

Nm A*- 33 3..;

CI)

I - 9%.

94 C mm 3,4

  • ~:

---. 3 U CV 9 3

C- ~ £ 343 r,.

0 O

  • .5-
im E

N -

Nm C4NM N -

wWmm- ALAii N

2 C

3

'C.- 0

.9 II 0

3

('4 V O Surveyed Grids .9 8

V Figure provided by SMUD Figure A-7: Survey Unit F8110113, -27 to 25 Feet Elevation Rancho Seco Nuclear Generating Station A-7 16,9S-SR-05-0

GRIDl1 GRID 27 GRID 28 GRID 51 GRID 63 GRID 99 GRID 110 GRID 122 GRID 170 GRID 171 MEASUREMENT/SAMPLE 0 5 LOCATION ,_ _ _

    1. SINGLE POINT SCALE (in meters)

Figure A-8: Survey Unit F8110113 - Direct Measurement Locations Rancho Seco Nuclear Generating Station A-8 1695-SR-05-0

MEASUREMENT/SAMPLE LOCATIONN

  1. SINGLE POINT NOT TO SCALE Figure A-9: Survey Unit F8110114, Floor - Direct Measurement Locations Rancho Seco Nuclear Generating Station A-9 1695-SR-05-0

5f I

Figure provided by SMUD MEASUREMENT/SAMPLE LOCATION N 0 SINGLE POINT Figure A-10: Survey Unit F8110114, B Sump - Direct Measurement Locations Rancho Seco Nuclear Generating Station A-10 1695-SR-05-0

0 ~~12' 3" --

11GS 12GS 13GS 114GS U- U- U- U- U- U ~W 28GS 15GS 29GS 30GS 1 31GS 2

27GS 16GS 01 3 32GS 33GS 34GS 17GS 16' 26GS 108G 25GS 18GS 35GS 36GS 37GS 24GS 19GS

-p-i - - - - I 4' 1 1/4" 23GS122GS121GS 20GS

- h * - U-Figure provided by SMUD MEASUREMENT/SAMPLE LOCATION N -as 0 SINGLE POINT Figure A-11: Survey Unit F8110114, Emergency Sump - Direct Measurement Locations Rancho Seco Nuclear Generating Station A-1 1 1695-SR-05-0

APPENDIX B TABLES Rancho Seco Nuclear Generating Station 1695-SR-05-0

I i Containment .GrojssBeta-DCGLb Design DCGLEMCC Building Liner' ls (dpm/100 cm2 ) (dpmn/10 cm 2 ) /Area Factor' F8110111, Containment.

Building Wall,' 1 43,000 640,700/14.9 Elevation 75 to 115 feet F8110112, Containment Building Wall, 1 43,000 640,700/14.9 Elevation 25 to 75 feet F8i10113, Containment Building Wall, 1 43,000 640,700/14.9 Elevation -27 to 25 feet' F8110114, Containment 43,000 640,700/14.9 Building Floor,.-27 feet aRefer to Figures A-3 through A-11.

bGross beta DCGL accounts for radionuclide fractions and hard to detects as specified in the DTBD-05-15 (SMUD 2006b).

cDCGLEMc provided by SMUD and accounted for area factors (also provided by SMUD) determined for each specific survey unit.

Rancho Seco Nuclear Generating Station B-1 1695-SR-05-0

HERLD CAIORI Percent scan Coverage Containment Building Class Gamma Beta Beta Survey Unita Floor Floor Wall Surfaces F81 10111, Containment Building Wall, Elevation NAb NA 60 75 to 115 feet F8110112, Containment Building Wall,' Elevation 1 NA NA 60 25 to 75 feet F81 10113, Containment Building Wall, Elevation 1 NA NA 50

-27 to 25 feet F8110114, Containment 1 100 50 NA Building Floor, -27 feet

ýRefer to Figures A-3 through A-11.

bNot Applicable.

Rancho Seco Nuclear Generating Station B-2 1695-SR-05-0

Containment  :,[Removable Activity.

Building grie Totai.Beta Activity _ (dpm/100. _M2)Acvtyrg tlets Liner ....... .(dpm/100 cmh)C Locationa Alpha " Beta FDCGL/DCGLEMC d F8110111, Reactor Containment 75 to 115 feet Grid M0049 o______' __....

1 US 5,000 -- YES/YES 2 US 3,400 .... YES/YES 3 US 3,200 .... YES/YES 4 US 2,800 .... YES/YES 5 US 23,000 6 75 YES/YES Grid M0053 1 US 30,000 6 140 YES/YES 2 US 31,000 6 210 YES/YES 3 US 43,000 8 210 YES/YES 4 US 21,000 6 200 YES/YES 5 US 8,900 2 55 YES/YES Grid M0065 _ ._ _ _ _ _ _ _ . __ ._.__"

1 US 800 2 17 YES/YES 2 US 1,600 ..

-- YES/YES 3 US 1,300 .... YES/YES 4 US 540 .... YES/YES 5 US 1,100 .... YES/YES Grid M0068 .___

1 US 1,200 6 18 YES/YES 2 US 7,100 2 13 YES/YES 3 US 32,000 0 3 YES/YES 4 US 5,900 4 30 YES/YES Grid M0073 -. . -

1 US 7,600 2 59 YES/YES 2 US 180,000 170 3,400 NO/YES 3 US 39,000 2 4 YES/YES 4 US 4,300 0 12 YES/YES 5 US 19,000 0 35 YES/YES Rancho Seco Nuclear Generating Station B-3 1695-SR-05-0

Containment ] ,Rernovable Activity. Atvt et Building gnC.ebTotal Beta Activity __(dpm/100 c2 "r*R.~

Liner (dpm/100 cmL)c Alpha Beta DCGL/DCGLEMCd Locationa F8110111, Reactor Containment 75 to 115 feet Grid M0128 __ ____

1 US 31,000 0 -2 YES/YES 2 US 7,500 -- -- YES/YES 3 US 15,000 .... YES/YES 4 US 8,200 .... YES/YES 5 US 8,200 .... YES/YES Grid M0129 1 US 130,000 62 1,400 NO/YES 2 US 7,600 -- -- YES/YES 3 US 13,000 .... YES/YES 4 US 88,000 .... NO/YES 5 US 35,000 .... YES/YES Grid M0135 -_

1 US 18,000 .... YES/YES 2 US 6,300 -- -- YES/YES 3 US 30,000 21 450 YES/YES 4 US 8,400 -- -- YES/YES 5 US 12,000 .... YES/YES Grid M0138 1 US 19,000 .... YES/YES 2 US 21,000 -- -- YES/YES 3 US 59,000 4 25 NO/YES 4 US 4,900 ..-- YES/YES 5 US 4,900 -... YES/YES Rancho Seco Nuclear Generating Station B-4 1695-SR-05-0

SUFC ACIVT LEmVabLS ciiy ._ ...

BContainment B: '(o Building +/-*CUVlty ivieets Total Beta Activity (dpm/100 cm)

Surfaceb 2 Gross Beta Liner (dpm/100 cm )c Alpha Beta DCGL/DCGLEMCd Locationa F8110112, Reactor Containment 25 to 75 feet Grid M0006 _ _ - _ _

1 US 2,600 -- -- YES/YES 2 Us 3,400 2 14 YES/YES 3 Us 3,200 -- -- YES/YES 4 Us 3,000 .... YES/YES 5 US 2,200 .... YES/YES Grid M0011 1 US 45,000 -- -- NO/YES 2 US 71,000 4 98 NO/YES 3 US 25,000 -- -- YES/YES 4 US 60,000 .... NO/YES 5 US 13,000 .... YES/YES Grid M0012 ____

1 US 9,100 .... YES/YES 2 US 46,000 8 69 NO/YES 3 US 28,000 -- -- YES/YES 4 US 15,000 .... YES/YES 5 US 20,000 .... YES/YES Grid M0022 1 US 15,000 .... YES/YES 2 US 6,400 .... YES/YES 3 US 6,600 .... YES/YES 4 US 41,000 .... YES/YES 5 US 100,000 0 18 NO/YES Rancho Seco Nuclear Generating Station B-5 1695-SR-05-0

IContainment .I l:I " I Removable Activity I A.._. *, I.

2 ivieets, Building Total Beta Activity (dpm/100 cm ) ti*cuvrity Surface b Gross Beta Liner (dpm/100 cruZ)cI Alpha. Beta DCGL/DCG_]EMcd Locationa F8110112, Reactor Containment 25 to 75 feet ,

Grid M0023 1 US 9,400 .... YES/YES 2 Us 29,000 .

-- YES/YES 3 US 54,000 -- -- NO/YES 4 Us 31,000 .... YES/YES 5 US 73,000 2 46 NO/YES Grid M0027 __ ..

1 US 87,000 4 68 NO/YES 2 US 2,600 -- -- YES/YES 3 US 10,000 .... YES/YES 4 US 18,000 .... YES/YES 5 US 1,500 .... YES/YES Grid M0056 _ _ _ _ _ _ _ _

1 US 7,500 .... YES/YES 2 US 2,900 .... YES/YES 3 US 7,700 0 57 YES/YES 4 US 6,200 -- -- YES/YES 5 US 3,000 .... YES/YES Grid M0124 _ _.... "___

1 US 330 .... YES/YES 2 US 56 .... YES/YES 3 US 380 -- -- YES/YES 4 US 430 0 1 YES/YES 5 US 420 .... YES/YES Grid M0167 1 US 3,200 .... YES/YES 2 US 1,600 .... YES/YES 3 US 4,800 -- -- YES/YES 4 US 15,000 0 9 YES/YES 5 US 7,200 -- -- YES/YES Rancho Seco Nuclear Generating Station B-6 1695-SR-05-0

1 US 2,300 .... YES/YES 2 Us 760 ... YES/YES 3 us 570 .... YES/YES 4 Us 5,300 0 23 YES/YES 5 Us 1,300 ... YES/YES 1 US 12,000 0 12 YES/YES 2 US 6,600 -- - YES/YES 3 us 5,400 ... YES/YES 4 US 1,400 ... YES/YES 5 US 2,500 .... YES/YES 1 US 2,900 .... YES/YES 2 US 1,900 .... YES/YES 3 US 2,400 -- -- YES/YES 4 US 7,600 2 23 YES/YES 5 US 5,600 .... YES/YES 1 US 2,400 .... YES/YES 2 US 720 .... YES/YES 3 US 1,600 .... YES/YES 4 US 1,700 .... YES/YES 5 US 4,700 0 12 YES/YES Grid MO6 -

1 US 800 -- -- YES/YES 2 US 340 -- -- YES/YES 3 us 15,000 0 17 YES/YES 4 US 34,000 4 98 YES/YES 5 US 1,600 -- -- YES/YES 6 US 15,000 .... YES/YES Rancho Seco Nuclear Generadng Station B-7 1695-SR-05-0

TABL B-3 (cn.)

SURAC ACIVT LEEL Containment Removable Activity

" (dpm/100 cm 2) Activity Meets Building -c Total Beta Activity Gross Beta Liner (dpm/100 cm 2)c Alpha Beta ' I DCGL/DCGLEMCd Locationa

&I I. II F8110113, Reactor Containment -27 to 25 feet Grid M 00990 ._......... .. ____ .... ____

1 US 16,000 0 17 YES/YES 2 US 15,000 0 6 YES/YES 3 US 300 -- -- YES/YES 4 US 23,000 - YES/YES 5 US 160 ..... YES/YES Grid M0110 _"__ _ _

1 US 1,500 .... YES/YES 2 US 680 .... YES/YES 3 US 650 .... YES/YES 4 US 190 .... YES/YES 5 US 350 .... YES/YES Grid M0122 1 US 3,700 .... YES/YES 2 US 3,100 .... YES/YES 3 US 6,600 .... YES/YES 4 US -76 .... YES/YES 5 US 4,700 0 17 YES/YES Grid M0170 1 LW 2,600 .... YES/YES 2 LW 3,200 -- -- YES/YES 3 LW 5,600 2 5 YES/YES 4 LW 5,700 -- -- YES/YES 5 LW 99 .... YES/YES 6 LW 8,600 --. YES/YES 7 LW 78,000 0 13 NO/YES Grid M0171 1 LW 44,000 4 50 NO/YES Rancho Seco Nuclear Generating Station B-8 1695-SR-05-0

Continmnt

. R~movable Activity Building ',bTotal Beta Activity (dpm/100 cm2 ) Atvy Meta Liner . (dpm/i00 cm')c DCGL/DCGLEMc d Location' p p -

F8110114, Floor and Sumps II-BSump ' YE"..

1 LW 4,300 -- YES/YES 2 FL 1,300 .... YES/YES Em3 gency S-13 ... YE.

1 Before LW 130,000 0 -2 ENO/YES Flo1rAfter um _LW__

  • 2,500 -- YES/YES 2 LW 15,000 2- YES/YES 3 FL -13 0... YES/YES FlooL 40 0 -YE/S 1 FL 34,000 0 4 YES/YES 2 FL 220 2 -4 YES/YES 3 FL 5,700 2 3 YES/YES 4 FL 470 0 -1 YES/YES 5 FL 40 0 -1 YES/YES 6 FL 39,000 0 7 YES/YES 7 FL 390 0 3 YES/YES 8 FL 10,000 0 8 YES/YES 9 FL 9,100 2 5 YES/YES 10 FL 9,200 0 -3 YES/YES 11 FL 12,000 0 5 YES/YES 12 FL 5,900 0 -4 YES/YES 13 FL 8,100 0 4 YES/YES 14 FL 22,000 1 0 -2 YES/YES aRefer to Figures A-3 through A-11.

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 B-1. All surface activity measurements that were greater than the gross beta DCGL were less than the design DCGLI*mcs determined for each specific survey unit.

eRemovable activity measurement not performed.

Rancho Seco Nuclear Generating Station B-9 1695-SR-05-0

APPENDIX C MAJOR INSTRUMENTATION Rancho Sect Nuclear Generating Station 1695-SR-05-0

APPENDIX C MAJOR INSTRUMENTATION The display of a specific product is not to be construed as an endorsement of the product or its manufacturer by the author or his employer.

SCANNING INSTRUMENT/DETECTOR COMBINATIONS Beta Ludlum Floor Monitor Model 239-1 combined with Ludlum Ratemeter-Scaler Model 2221 coupled to Ludlum Gas Proportional Detector Model 43-37, Physical Area: 550 cm 2 (Ludlum Measurements, Inc., Sweetwater, TX)

Ludlum Ratemeter-Scaler Model 2221 coupled to 2 Ludlum Gas Proportional Detector Model 43-68, Physical Area: 126 cm (Ludlum Measurements, Inc., Sweetwater, TX)

Gamma Ludlum Pulse Ratemeter Model 12 (Ludlum Measurements, Inc., Sweerwater, TX) coupled to Fluke Miomedical NaI(Tl) Scintillation Detector Model 489-55, Crystal: 3.2 cm x 3.8 cm (Fluke Biomedical, Cleveland, OH)

DIRECT MEASUREMENT INSTRUMENT/DETECTOR COMBINATIONS Beta Ludlum Ratemeter-Scaler Model 2221 coupled to Ludlum Gas Proportional Detector Model 43-68, Physical Area: 126 cm 2 (Ludlum Measurements, Inc., Sweetwater, TX)

LABORATORY ANALYTICAL INSTRUMENTATION Low Background Gas Proportional Counter Model LB-5100-W (Tennelec/Canberra, Meriden, CT)

Rancho Seco Nuclear Generating Station C-1 1695-SR-05-0

APPENDIX D SURVEY AND ANALYTICAL PROCEDURES Rancho Seco Nuclear Generating Station 1695-SR-05-0

APPENDIX D SURVEY AND ANALYTICAL PROCEDURES PROJECT HEALTH AND SAFETY The proposed survey and sampling procedures were evaluated to ensure that any hazards inherent to the procedures themselves were addressed in current job hazard analyses (JHA). All survey and laboratory activities were conducted in accordance with ORISE health and safety and radiation protection procedures.

Pre-survey activities included the evaluation and identification of potential health and safety issues.

Survey work was performed per the ORISE generic health and safety plans and a site-specific integrated safety management (ISM) pre-job hazard checklist. SMUD also provided site-specific safety awareness training.

CALIBRATION AND QUALITY ASSURANCE Calibration of all field and laboratory instrumentation was based on standards/sources, traceable to the National Institute of Standards and Technology (NIST).

Analytical and field survey activities were conducted in accordance with procedures from the following ORAU and ORISE documents:

- Survey Procedures Manual (May 2008)

- Laboratory Procedures Manual (December 2008)

- Quality Program Manual (November 2007)

The procedures contained in these manuals were developed to meet the requirements of 10 CFR 830 Subpart A, QualityAssurance Requirements, Department of Energy Order 414.1 C Quality Assurance, and the U.S. Nuclear Regulatory Commission Qualioy Assurance Manualforthe Office of NuclearMaterial Safey and Safeguards and contain measures to assess processes during their performance.

Quality control procedures include:

Daily instrument background and check-source measurements to confirm that equipment operation is within acceptable statistical fluctuations.

Rancho Sect Nuclear Generating Station D-1 1695-SR-05-0

  • Participation in Mixed-Analyte Performance Evaluation Program (MAPEP), NIST Radiochemistry Intercomparison Testing Program (NRIP), and Intercomparison Testing Program (ITP) Laboratory Quality Assurance Programs.
  • Training and certification of all individuals performing procedures.

" Periodic internal and external audits.

CALIBRATION PROCEDURES Detectors used for assessing surface activity of the Containment Building walls and sumps were calibrated in accordance with ISO-75032 recommendations. The total beta efficiency (gotD was determined for the instrument/detector combination used for all surface activity measurements and consisted of the product of the 271 instrument efficiency (E) and surface efficiency (C5 ): tot =Ei X .

The total surface efficiency for the walls and floor sumps was determined based on a beta energy multi-point calibration, development of instrument efficiency to beta energy calibration curves, and the calculation of the weighted efficiency representing the primary contaminants of concern (Cs-137 and Co-60) for the RSNGS site. SMUD calculated the radionucide mix fraction of Cs-137 to Co-60 as 0.87 and 0.13, respectively (SMUD 2006b).

Carbon-14 (C-14), technetium-99 (Tc-99), thallium-204 (Tl-204), and strontium/yttrium-90 (Sr/Y-90) were selected as the beta calibration sources to represent the energy distribution of the detectable beta-emitters at the RSNGS. The 27z interpolated F, factors for the detectable beta-emitters ranged from 0.34 to 0.67 for the gas proportional detectors (Example provided in Figure D-1). 1SO-7503 recommends an E;of 0.25 for beta emitters with a maximum energy of less than 0.4 MeV and an F, of 0.5 for maximum beta energies greater than 0.4 MeV. The ORISE calculated multi-point calibration total weighted static 8 totl values for the hand-held gas proportional detectors used for the confirmatory surveys was 0.24.

For the Containment Building floor, Tc-99 was selected as the only beta calibration source in determining the total surface efficiency for the floor. The 2rz beta ej factor for the gas proportional detector used to collect direct measurements was 0.44. ISO-7503 recommends an Es of 0.25 for

'International Standard. ISO 7503-1, Evaluation of Surface Contamination - Part 1: Beta-emitters (maximum beta energy greater than 0.15 MeV) and alpha-emitters. August 1, 1988.

Rancho Seco Nuclear Generating Station D-2 1695-SR-05-0

maximum beta energies less than 0.4 MeV (the maximum beta energy of Co-60 is 0.314 MeV).

Since RSNGS provided a ratio (mentioned above) for Cs-137 and Co-60, ORISE determined a weighted total beta efficiency using an F, of 0.5 for the Cs-137 and an F, of 0.25 for the Co-60. The resulting total beta efficiency was 0.21.

SURVEY PROCEDURES Action Levels The field action level for the hand-held gas proportional instrument based on the specific site criteria and background was calculated as follows:

  • SMUD Site Release Criteria (SRC): 43,000 dpm/100 cm 2 0 43-68 multipoint total efficiency (r ota: 0.24
  • Background (BKG): 250cpm
  • Time (T): 1 minute count time 2
  • *G ==geomery -=0 geometry =Physical Detector Area CM 100 Determine Action Level

" Action Level (cpm) = (SRC

  • total** G
  • T) + (BKG
  • T)
  • Action Level = 13,253 cpm A field count at or above the calculated action level value indicates that further investigation of the area would be necessary.

Surface Scans Structural surface scans were performed by passing the detectors slowly over the surface; the distance'between the detector and the surface was maintained at a minimum-nominally about 1 cm. Building surfaces were scanned using a floor monitor (550 cm 2 ) and/or a small area (126 cm 2) hand-held gas proportional detector. A Nal scintillation detector was used to scan for elevated gamma radiation throughout the SUs. Identification of elevated radiation levels was based on increases in the audible signal from the recording and/or indicating instrument.

Rancho Seco Nuclear Generating Station D-3 1695-SR-05-0

Specific scan minimum detectable concentrations (MDC) for the Nal scintillation detector for Cs-137 and Co-60 in concrete were not specifically determined as the instrument was used solely as a qualitative means to identify elevated gamma activity where further investigation would be required. MDCs for radionuclides in the concrete would approximate those contained in NUREG-1507.

Beta surface scan MDCs were estimated using the calculational approach described in NUREG-1507.3 The scan MDC is a function of many variables, including the background level.

Additional parameters selected for the calculation of scan MDCs included a one-second observation interval, a specified level of performance at the first scanning stage of 95% true positive rate and 25% false positive rate, which yields a d'value of 2.32 (NUREG-1507, Table 6.1), and a surveyor efficiency of 0.5. The scanning etotal was determined for the hand-held gas proportional and floor monitor detectors in the same fashion as above for the static hand-held gas proportional detectors except typical scanning efficiencies for the detectors were used rather than specific calibrations for this survey. The scanning Etotal value for a hand-held gas proportional detector was 0.18 (Figure D-2) and 0.15 for a floor monitor (Figure D-3).

To illustrate an example for a hand-held gas proportional detector using a concrete background of 560 cpm, the minimum detectable count rate (MDCR) and scan MDC can be calculated using the following relationships:

Si = d'(b). /2; MDCR = si * (60/i); and MDCR..rveyor =MDCR/(P) 1/2 Where:

s= the minimum detectable number of source counts d' the specified level of performance of 2.32 bi the number of background counts in the observation interval MDCR = minimum detectable count rate i observation interval p surveyor efficiency of 0.5 3

NUREG-1507. Minimum Detectable Concentrations With Typical Radiation Survey Instruments for Various Contaminants and Field Conditions. US Nuclear Regulatory Commission. Washington, DC; June 1998.

Rancho Seco Nuclear Generating Station D-4 1695-SR-05-0

The equations are combined and the variables are then calculated as follows:

bi = (250 cpm)(1 s)(1 min/60 s) = 4.17 counts, MDCR = (2.32)(4.17 counts)" [(60 s/min)/(1 s)] = 284 cpm, MDCR,..eyor = 284/(0.5)/'1/2 = 402 cpm The scan MDC is calculated assuming a total efficiency (8tota of 0.18:

MD/*CRsuvyrdm/1O m ScanMDC = dp)m/100CM2 suRveyor For the given background, the estimated scan MDC was 2,228 dpm/100 cm 2 for the hand-held gas proportional detector. In the same manner, the scan MDCs for the floor monitor detector was 6,367 dpm/100 cm 2 (Refer to Figures D-2 and D-3).

Surface Activity Measurements Measurements of total beta surface activity levels were performed using hand-held gas proportional detectors coupled to portable ratemeter-scalers. Count rates which were integrated over one minute with the detector held in a static position, were converted to activity levels (dpm/100 cm 2) by dividing the count rate by the total static efficiency (EiX~s) and correcting for the physical area of the detector. ORISE did not determine construction material-specific backgrounds for each surface type encountered for determining net count rates. Instead, ORISE took the conservative approach and did not subtract material specific backgrounds in determining surface activity levels.

The MDC for surface activity measurements was calculated using the following equation:

DC = 3 + (4.65 KG T

  • cTotaI
  • G Where:

BKG = background (total counts) in time interval, T T = count time (min) used for field instruments Rancho Seco Nuclear Generating Station D-5 1(*95-SR-05-0

&rotal = total efficiency = Ej x E, Ei = instrument efficiency E, = source efficiency G = geometry (physical detector area cm 2/100)

The beta static MDC for the gas proportional detector was 258 dpm/100 cm 2 using the total efficiency of 0.24 and an instrument background of 250 cpm (Figure D-1). The physical surface area assessed by the gas proportional detector used was 126 cm 2 .

Removable Activity Measurements Smear samples for removable gross alpha and gross beta contamination were obtained from biased direct measurement locations based on surface activity measurement results. Removable activity samples were collected using numbered filter paper disks, 47 mm in diameter. Moderate pressure 2

was applied to the smear and approximately 100 cm of the surface was wiped. Smears were placed in labeled envelopes with the location and other pertinent information recorded.

RADIOLOGICAL ANALYSIS Gross Alpha/Beta Smears were counted on a low-background gas proportional system for gross alpha and beta activity.

The MDCs of the procedure were 11 dpm/100 cm 2 and 14 dpm/100 cm 2 for a 2-minute count time for gross alpha and gross beta, respectively.

DETECTION LIMITS Detection limits, referred to as minimum detectable concentrations, were based on 3 plus 4.65 times the standard deviation of the background count [3 + (4.65 (BKG)1 /2)]. Because of variations in background levels, measurement efficiencies, and contributions from other radionuclides in samples, the detection limits differ from sample to sample and instrument to instrument.

Rancho Seco Nuclear Generating Station D-6 1695-SR-05-0

Task Number: 1695 SITE: Rancho Seco Dat Ent Instrument: 222106 Detector: 43-68 #6 (08 mg/cm 2 window)

Site BKG Avg (cpm): 250 Calibration Data Average Beta Maximum Beta Instrument Radionuclide Energy (keV)l Energy (keV) 1 E C-14 49.47 156.5 0.36 Tc-99 84.6 293.5 0.39 TI-204 244-03 763.4 0.57 Sr/Y-90 2 564.75 1413.05 0.64 43-68 Instrument Efficiency (0.8 mglcm 2 window)

I 0.70 y 0.12381n(x) - 0.1343 R

0.60 c 0.50

.2 Fy"'= 01369In(x) - 0.35281 S0.40 z 0.30 E

0.20 0.10 0.00 0 200 400 600 800 1000 1200 1400 1600 Beta Energy (keV)

[ Average U Maximum - Log. (Average) - Log. (Maximum)

Radionuclide Mix Calculation Average Beta Maximum Beta Instrument Surface Weighted Radionuclide Energy (keV) 1 Energy (keV)1 Fraction 3 Efficiency4 Efficiency Efficiency Cs-137 187 550 0.87 0.51 0.50 0.22 Co-60 96 318 0.13 0.43 0.25 0.01 Totl Eaciency: 024 Staic MDC (dpm/lOO cm 2): 258 http://, =dc. bnLgovl/aadt2/dee-sea1eb2isp Average and maýaama Si/Y.90 beta exerge calmhated. by adding the average and maairnns energies of both radionwdides, respectively, and dividing by two 3 Faetion based on data provided by SAL'D 4 Calculated using eponential enxve shown above for average beta eney.r Figure D-1: Multipoint Hand-Held Gas Proportional Detector Static MDC - Instrument #6 Rancho Seco Nuclear Generating Station D-7 1695-SR-05-0

Task Number: 1695 SITE: Rancho Seco Data Entrv oi = I sec Instrument: 2221 (06 m Surveyor Eff. = 0.5 --

43-68 #6 (0.8 mg/cm2 window) bi = 4.2 counts Detector:

Cal BKG Avg (cpm): 2.50 MDCR = 284 cpm MDCRI , = 402 cpm Calibration Data Average Beta Maximum Beta Instrument Radionuclide Energy (keV)l Energy (keV)t Efficiency2 C-14 49.74 156.5 0.28 Tc-99 84.6 293.5 0.30 T1-204 244.03 763.4 0.46 Sr/Y-903 564.75 1413.05 0.46 43-68 Instrument Efficiency (0.8 mg/cm2 window) 0.60 - y = 0.0854ir(x) - 0.0556 R2 - 0.8855 0.50 y = 0.09541n(x) - 0.2124

.2 0.40 R2 0.9002

=0.30 a"I

.2 E 0.20

- 0.10 0.00 0 200 400 600 800 1000 1200 1400 1600 Beta Energy (keV)

  • Average 0 Maximum - Log. (Average) ------ Log. (Maximum)

Radionuclide Mix Calculation Average Beta Maximum Beta Instrument Surface Weighted Radionuclide Energy (ke1)3 Energy (ke7)I Fraction4 Efficiency7 Efficiency Effic5enc0 Cs-137 187 550 0.87 0.39 0.50 0.17 Co-60 96 318 1 0.13 0.33 0.25 0.01 TotalHffeiency- 0.18 Scan MDC (dp=/lOOcm 2) 2,228 h*/!-e-nnde bo~gov/wtdat2 /dee.s.amehb~sp hi!

Devom os-ong Health Phy-, Table 9.3 A-Vteg. and -oronSx/Y-90 beta eaneq.e ealviated br eddmg the average and mao ma eregses of both t%,honoohdes, zespeotmely, and d-idmg by t 4Ftacton based on data provided by SMUD Caknlstd.a, uoog eaponenawt£ tcve sho.a. above fot average beta .aaeqgy Figure D-2: Multipoint Hand-Held Gas Proportional Detector Scan MDC - Instrument #6 Rancho Seco Nuclear Generating Station D-8 1695-SR-05-0

Task Number: 1695 SITE: Rancho Seco Data Entry 0,= 1 sec Sunreyor Eft. = 0.5 -

Instrument: 2221 F ( gd#2 bi = 24.2 counts 43-37 #9 (0.8 mng/cmn2 window)

Detector:

Cal. BKG Avg (cpm): 14,50 MDCR = 684 cpm XIDCR,,X 968 cpm Calibration Data Average Beta Maximum Beta Instrument Radionuclide Energy (keV)1 Energy (kel)p Efficiency2 C-14 49.74 156.5 0.18 Tc-99 84.6 293.5 0.24 TI-204 244.03 763.4 0.39 SI/Y-903 564.75 141305 0.42 43-37 Instrument Efficiency (0.8 mg/cm 2 window) 0.50 - y = 0.10431n(x) - 02185 0.45 R2 = 0.9544

,> 0.40

- 0.35 0-41

~0,30 0.25

$E 0.20 o

. 0.15 0.10 0.05 0.00 0 200 400 600 800 1000 1200 1400 1600 Beta Energy (keV)

Average U Maximum - Log. (Average) .....- Log. (Maximlutr)

Radionuclide Mix Calculation Average Beta Maximum Beta Instrument Surface Weighted 4

Radionuclide Energy (keV)J Energy (keV)' Fraction Efficiency Efficiency Efficiency Cs-137 187 550 0-87 0.33 0.50 0.14 Co-60 96 318 0.13 0.26 025 0.01 0.15 Tota Efflciency Scan MDC (dpm/llO0 cm 2): 6,367 t

http://www.nnckbnl.gov/nuWat2/dec_seach isp Decomnsionig Health Phlucs, Table 9.2 Avenage and maximumn Sr/.'-90 beta eneqges calculated by adding the avefage and maximum energies of both radionrclides. respectively, and dividing by two 4Fraction based on data provided by S2tUD

'Calculated ming exponential cutre shosn above for average beta energy Figure D-3: Multipoint Floor Monitor Gas Proportional Detector Scan MDC - Instrument #2/#9 Rancho Seco Nuclear Generating Station D-9 1695-SR-05-0

Retrieved from "https://kanterella.com/w/index.php?title=ML091350468&oldid=2563368"