Text

Historical Site Assessment, Revision 1
	ML062220351
Person / Time
Site:	Rancho Seco
Issue date:	08/03/2006
From:	Rosalyn Jones; Sacramento Municipal Utility District (SMUD)
To:	; Document Control Desk, NRC/FSME
References
	NQA 06-028
	Download: ML062220351 (79)
	v • d • e

P 4 F SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT The Power To Do More.'RO. Box 15830, Sacramento, CA 95852-1830; 1-888-742-SMUD (7683)NQA 06-028 August 3, 2006 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 RANCHO SECO HISTORICAL SITE ASSESSMENT, REVISION 1 Attention:

John Hickman Attached is the Rancho Seco Historical Site Assessment (HSA), Revision 1, dated August 2006.The changes include the addition of Section 6.9.5 to address the absence of onsite disposal of radioactive materials, a revision to Figures 4.1, 6.1, and 6.2 to match those used in the LTP submittal, and other editorial corrections.

Please replace the existing HAS, Revision 0 pages from the cover page through page72 with the attached HAS, Revision 1 from the cover page through page72. Appendices A through E remain unchanged.

Members of your staff with questions requiring additional information or clarification may contact me at (916) 732-4843.Sincerely, bet ones Supe ioing Quality Engineer Cc w/ attachment:

NRC Region IVý ýýý I RANCHO SECO NUCLEAR PLANT e 14440 Twin Cities Road, Herald, CA 95638-9799; (209) 333-2935 Sacramento Municipal Utility District Rancho Seco Nuclear Generating Station Historical Site Assessment Revision 1 August 2006 Historical Site Assessment Document Approval REVISION

SUMMARY

Various Sections:

Perform editorial corrections Section 6.9: Added Section 6.9.5 to address the absence of onsite disposal of radioactive materials Figures 4.1, 6.1 and 6.2: Revised figures to match those used in the LTP submittal Decommissioning status was not updated to reflect current progress Document Approved by: a- T. i Dismantlement Superintendent (Radiological)

I Table of Contents 1.0 Introduction

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3 2.0 Objectives of Historical Site Assessmient...............................................

7 3.0 Tems A.cronymis, and Abbreviations................................................

9 4.0 Property Identification

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13 4.1 Facility Characteristics

.................................................................

13 4. 1.1 Licensee Identification (DPR-54) ..................................................

13 4.1.2 Location..............................................................................

13 4.1.3 Topography

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15 4.1.4 Stratigraphy

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15 4.2 Environmental Characteristics.........................................................

16 4.2.1 Geology...............................................................................

16 4.2.2 Seismology...........................................................................

16 4.2.3 Hydrology

.. .........................................................................

18 4.2.4 Hydrogeology........................................................................

18 4.2.5 Meteorology..........................................................................

21 5.0 USA. Methodology

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25 5.1 Approach and Rationale................................................................

25 5.2 Documents reviewed ...................................................................

25 5.3 Site Reconnaissance

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26 5.4 Personnel Interviews

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26 5.5 Historical Construction Photograph Review .........................................

28 6.0 Operational History .....................................................................

29 6.1 Introduction

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29 6.2 Decommissioning Plan Chronology

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32 6.3 Regulatory Overview...................................................................

33 6.3.1 Permits and Licenses .................................................................

33 6.4 Waste Handling Procedures..................................

i.........................

36 6.4.1 Process Control Program (PCP)....................................................

36 6.4.2 Rancho Seco Administrative Procedures (RSAP).................................

36 6.4.3 Radiation Control Manual (RCM)..................................................

37 6.4.4 Radwaste Control Manual (RWCM)...............................................

37 6.4.5 Chemistry Department Procedures Manual........................................

37 6.4.6 Surveillance Procedures (SP) .......................................................

37 6.5 Current Site Usage .....................................................................

37 Revision 1 RSNGS Historical Site Assessment i August 2006 6.5.1 Description of Operations

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37 6.5.2 Prelim inary Site Characterization

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37 6.6 Site Dism antlem ent ...........................................................................................

38 6.6.1 Dismantlement activities within the Power Block ..........................................

38 6.6.2 Dismantlement activities outside the Power Block ......................................

38 6.7 Radiological Sources ..........................................................................................

38 6.7.1 Spent Fuel .....................................................................................................

38 6.7.2 Irradiated H ardw are ........................................................................................

39 6.7.3 Reactor V essel and Internals

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39 6.7.4 Plant System s .........................................................

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39 6.7.5 Industrial Area Contam ination .............................................................................

39 6.7.6 N on-Industrial Area Contam ination .............................................................

40 6.8 W aste Stream Description

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42 6.8.1 Hazardous Materials/Wastes

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42 6.8.2 Low Level Radioactive W aste (LLRW ) ........................................................

44 6.8.3 Spent Fuel ...........................................................................................................

46 6.9 Incident Descriptions

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46 6.9.1 Radiological Spills ........................................................................................

46 6.9.2 Chem ical Spills .............................................................................................

47 6.9.3 Loss of M aterial Control .................................................................................

47 6.9.4 System Cross-Contamination

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47 6.9.5 Onsite Disposal of Licensed Radioactive Materials

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48 6.10 Survey Unit Identification and Classification

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48 6.10.1 Site Classification

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48 6.10.2 A ssessm ent Perform ance ...........................................................................

48 6.10.3 Areas ..........................................................................................................

48 6.10.4 Survey Units ...............................................................................................

48 6.10.5 Initial D esignation of Areas .......................................................................

49 6.10.6 Survey U nit D esignation Program .............................................................

50 6.11 Radiological Im pact Sum m aries .............................................................................

54 6.11.1 Area I (SA O1)- Plant Effluent Area ........................................................

54 6.11.2 Area 2 (SA02) -South Plant Outfall Area ................................................

60 6.11.3 A reas 3 -7 .................................................................................................

60 6.11.4 A rea 8 (SA 08) .............................................................................................

61 6.11.5 Area 9 (SA09) .....................................................................................

........ 61 7.0 Findings ...........................................

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63 8.0 Conclusions

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67 9.0 R eferences 6.................................................................................................................

69 10.0 Appendices and A ddendum s ..............................................................................

71 Revision 1 RSNGS Historical Site Assessment ii August 2006 4.1 4.2 4.3 4.4 5.1 6.1 6.2 6.3 7.1 List of Tables Page Magnitude

/ Intensity Comparison

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17 Expected Extreme Wind Speeds .................................

22 Precipitation Climatology Averages (inches) .........................

23 Precipitation Intensity

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24 Personnel Observations Summary ................................

27 Operational History -RSNGS ...................................

30 Licenses and Permits ..............

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34 MARSSIM Survey Unit Classification Matrix .............................................................

53 A rea D esignations

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..................

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65 Revision 1 S Historical Site, Assessment iii August 2006 RSNG 4.1 4.2 6.1 6.2 List of Figures Rancho Seco Property M ap.................................................................................

14 Ground W ater Contour M ap ..................................................................................

20 Impacted Area Designations

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51 Area Designations

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52 Revision 1 S Historical Site Assessment iv August 2006 RSNG Executive Summary The Sacramento Municipal Utility District (herein referred to as the District) has conducted the Historical Site Assessment (HSA) of its Rancho Seco Nuclear Generating:

Station (RSNGS) in support of the ultimate decommissioning and license termination of the facility.The HSA, as a preliminary component in the Radiological Site Survey Investigation (RSSI), will provide guidance for subsequent activities, culminating with the final status survey (FSS) and license termination.

The HSA will designate the initial segregation of the site into various Areas and Survey Units and provide guidance in the development of the procedures and maps required to document the characterization, remediation, and ultimate 10 CFR Part 50 license termination of the site when compared to the release criteria referenced in the MARSSIM standard.The HSA was developed consistent with the methodology described in NUREG-1575,"Multi-Agency Radiation Survey and Site Investigation Manual"; including personnel interviews, and detailed record reviews.RSNGS operated from 1974 through 1989 within a highly regulated environment, which continues today. This highly regulated and documented environment provided a significant foundation for the development of the HSA.The evaluations performed to date identify locations outside of the historic power block where radioactive material contamination may have occurred due to various causes such as spills or loss of material control. These locations have been designated as Impacted Areas requiring additional investigation prior to the FSS.The District-owned and controlled property, comprised of some 2480 acres, includes the 87 acre Industrial Area site. Of the nearly 2400 acres outside of the Industrial Area, approximately 80 acres have been impacted by licensed operations.

These include the Plant Liquid Effluent Discharge water course way to the Southwest of the site and the Storm Drain outfalls located to the South of the facility.

These two areas have been designated as Impacted.

The remaining 2300 acres outside of the Industrial Area have been designated as Non-Impacted areas. The Industrial Area is designated as Impacted based on the diversity of operations conducted in this area.The District believes that the information contained within the HSA and the resulting conclusions for site area classifications accurately describe the radiological conditions that currently exist at the site.Revision I RSNGS Historical Site Assessment 1 August 2006 This page intentionally left blank Revision 1 August 2006 RSNGS Historical Site Assessment 2

1.0 INTRODUCTION

The Sacramento Municipal Utility District (herein referred to as the District) has conducted the Historical Site Assessment of its Rancho Seco Nuclear Generating Station in accordance with the guidance of the Multi-Agency Radiation Survey and Site Investigation Manual,'NUREG-1575 (MARSSIM)

[Ref. 9.1] in support of the ultimate decommissioning and license termination of the facility.The HSA formally began in July 2001, after several preliminary radiological assessments of the facility operations and their impact on remediation necessary prior to the performance of the Final Status Surveys (FSSs). These preliminary surveys, collectively referred to as the"Radiological Characterization Plan for the Rancho Seco Nuclear Power Generating Station" (RCPRSNPGS)

[Ref. 9.2], were conducted shortly after the shut down and termination of commercial operation of the RSNGS in June 1989.This characterization effort was undertaken prior to the implementation of the MARSSIM guidelines and therefore, relied primarily on the guidance of NUREG/CR-2082 "Monitoring for Compliance With Decommissioning Termination Survey Criteria" [Ref. 9.3] and Nuclear Regulatory Commission (NRC) Draft Regulatory Guide DG-1005 For Nuclear Reactor Facilities. "Standard Format and Content for Decommissioning Plans for Nuclear Reactors"[Ref..9.4]

Additional surveys had been anticipated for the RCPRSNPGS.

These included Phase III surveys and the FSS, to be performed in the 2007 and 2011 time frame respectively (phases I& II having been completed prior to 1997). With the issuance of MARSSIM, these surveys will be incorporated into the MARSSIM directed site characterization, FSS design, and the District's License Termination Plan (LTP) for the facility, the schedule of which will be determined by the District's senior management.

The HSA consisted of a review of historical:

Plant incident records;* Plant maintenance records;* Plant modification records;* Plant radiological survey records; and* Regulatory reports submitted by the District to various governmental agencies.The HSA also included written questionnaires and oral interviews with current and past facility employees regarding historical incidents that posed potential impacts to the facility.A review of historic site aerial photographs and physical inspections of the facility were performed to verify and validate the results of the historical record reviews.These efforts were designed to document the District's detailed knowledge of those events with a potential to impact the decommissioning of the site and final termination of its license.Concurrent with the performance of the HSA was the initial segregation of the facility into individual areas and specific, uniquely identified, survey units. This provides the basis for Revision 1 RSNGS Historical Site Assessment 3 August 2006 development of area/unit specific site drawings and survey maps required to document the characterization, remediation, and final release survey process. A major output from the HSA process was the information used as the basis for the preliminary MARSSIM classifications of the initial survey units.The initial classification of the site areas is based on the historical information and site characterization data. Data from operational surveys, surveys performed in support of decommissioning, routine surveillance, or any other applicable data may be used to change the original classification of an area up to the time of the FSS as long as the classification reflects the level of residual activity existing prior to any remediation in the area.To prevent the spread of radioactive material, Rancho Seco was designed with multiple boundaries to contain the plants' radioactive materials within its many components, systems, and structures.

During the operation of the plant from 1974 through 1989, many of these systems and structures, (and many that were not designed to become contaminated) have been impacted due to the routine operations, non-routine events and maintenance activities associated with the operational and post operational history of the plant.The most significant of these systems and structures include: " Reactor Containment Building;" Auxiliary Building;" Spent Fuel Storage Building;,.'

Interim Onsite (radwaste)

Storage Building (IOSB);* Turbine Building;* Solidification Building;* Contractor Fab Shop;* TankFarm;* Regenerate Holdup Tanks;" Auxiliary Boilers;" Main and Auxiliary Steam Systems;* Main and Auxiliary Feed Water Systems;" Clean Drain System;" Component/Turbine Cooling Water Systems;* Nitrogen Gas System;* Service Air System;* Discharge piping from RHUTS;." Main circulating water basins.Revision 1 RSNGS Historical Site Assessment 4 August 2006

Retention basinsl "* Control Rod Drive Cooling System; and* Nuclear Service Cooling Water System.The initial MARSSIM classification of these areas, the majority of which lie within that area comprising the historic power-block, was based on the design function of the area of concern or the areas' operational history.These areas were given Impacted Area designations.

Should subsequent investigations over the course of the decommissioning project support reclassification, the circumstances and rationale will be appropriately documented.

During the operational history of the facility, radioactive liquid spills, waste processing and storage activities, and maintenance activities on contaminated equipment and components occurred outside of the Radiologically Controlled Area (RCA) but within the Industrial Area fence line. These events have resulted in the assignment of an Impacted Area designation for the Industrial Area. Should data acquired during the course of the decommissioning project support reclassification; the circumstances and rationale will be appropriately documented.

The District-controlled property areas outside of the Industrial Area have been initially classified as Non-Impacted with the exception of Area 100000 because of the land area north of the plant effluent watercourse and the plant effluent watercourse and Area 200000 because of the storm drain outfalls within the area. These two locations will be initially managed as Impacted Areas.The classification assignments of the areas outside of the Industrial Area have been substantiated by the non-Industrial Area surveys performed by Shonka Research Associates, Inc. (Rancho Seco Non-Industrial Area Survey Project, Final Report, June 26, 2001 [Ref.9.17]). This project provided direct scanning of over 300,000 square meters of surface area and documented over 80,000 gamma spectral samples without detection of radioactive material of plant origin above background (spiked fields and known contamination along the effluent canal the exceptions).

The program to terminate the RSNGS license (DPR-54), including the HSA, followed by scoping, characterization, and remediation surveys will provide the information required to fully characterize the facility.The MARSSIM process for preparing for FSS provides multiple opportunities to re-evaluate decisions reached during any phase of the program such that areas with preliminary classifications may be reclassified should subsequent information show these preliminary classifications as not justified.

The District believes the investigation associated with the development of this HSA has resulted in a knowledge base that accurately describes the areas of potential impact and provides a conservative basis for the initial classification of the site's survey units.Based on the recommendations contained in MARSSIM, these HSA results are presented as follows:* Section 1.0 -: Introduction; Revision 1 RSNGS Historical Site Assessment 5 August 2006

Section 2.0 -Objectives of the Historical Site Assessment:

General purpose of the Historical Site Assessment;" Section 3.0 -Terms, Acronyms, and Abbreviations:

Presents a listing of the abbreviations and acronyms used in the HSA;" Section 4.0 -Property Identification:

Physical and environmental characteristics of the facility;* Section 5.0 -HSA Methodology:

Methodology used in the development of the HSA;" Section 6.0 -Operational History: Operational history of site including summaries of the documents providing significant information contributing to the characterization of the facility;* Section 7.0 -Findings:

HSA findings on the potential contaminates and Impacted Areas, including descriptions of the major Areas and significant Survey Units;" Section 8.0 -Conclusions:

Conclusions of the HSA;* Section 9.0 -

References:

List of references applicable to the HSA; and" Section 10.0 -Appendices:

List of HSA appendices and addendums.

Revision 1 RSNGS Historical Site Assessment 6 August 2006 2.0 OBJECTIVES OF HISTORICAL'SITE ASSESSMENT The Sacramento Municipal Utility District conducted the Historical Site Assessment of the Rancho Seco Nuclear Generating Station to: " Identify known and potential sources of radioactive material and radioactively contaminated areas including systems, structures and environmental media bised on the investigation and evaluation of existing information;

-I" Identify areas of the site with no conceivable or likely potential for radioactive or hazardous materials contamination and assign a preliminary classification of Non-Impacted while assigning a preliminary classification of Impacted to all remaining portions of the site;" Evaluate the potential for migration of radiological and hazardous substances beyond the boundaries of the Industrial Area or District property;" Develop the records to be utilized during the design of subsequent scoping, characterization, remediation, and the FSS; and* Provide preliminary information necessary to identify and segregate the site into survey units evaluated against the criteria specified in the MARSSIM guidelines for classification.

This classification wiIl.designte the need for and level of remedial action required within a particular survey unit as well as the level of intensity required during the FSS.Revision 1 RSNGS Historical Site Assessment 7 August 2006 This page intentionally left blank RSNGS Historical Site Assessment 8 Revision 1 August 2006 3.0 TERMS, ACRONYMS, AND ABBREVIATIONS ACM: Asbestos Containing (or Contaminated)

Material AEC: Atomic Energy Commission (also USAEC)cc -Alpha: contamination with alpha emitting radionuclides when used in the context of radiological surveys. When used in the context of the statistical analysis of survey data, a will denote a Type I error (rejecting the null hypothesis when it is in fact true).AOC: Area of Concern 0 -Beta: contamination with beta emitting radionuclides when used in the context of radiological surveys. When used in the context of the statistical analysis of survey data, P will denote a Type II error (accepting the null hypothesis when it is in fact false).BOP: Balance Of Plant BWST: Borated Water Storage Tank CCPM: Corrected Counts per minute. (CPM minus background CPM)CCR: California Code of Regulations CCW: Component Cooling Water CFR: Code of Federal Regulations CEOA: California Environmental Quality Act.cm.2: Square centimeters Co-60: Cobalt-60 (radioactive isotope of cobalt metal)Counts per minute Cs-137: Cesium-137 (radioactive isotope of cesium)CSCA: Controlled Surface Contamination Area CST: Condensate Storage Tank DCGL: Derived Concentration Guideline Level dpm: Disintegrations per minute (DPM, Dpm, or dpm).dpm/100cm2

Disintegrations per minute per 100 square centimeter surface area (or dpml1OO cm2)DSAR: Defueled Safety Analysis Report DTSC: Department of Toxic Substance Control. California agency regulating hazardous materials and waste EPA: Environmental Protection Agency (also USEPA)FONSI: Finding of No Significant Impact FSAR: Final Safety Analysis Report Revision 1 RSNGS Historical Site Assessment 9 August 2006 Terms, Acronyms, and Abbreviations (Continued)

FSS: Final Status Survey Ft: feet Y -Gamma: contamination with gamma emitting radionuclides when used in the context of radiological surveys.GEIS: Generic Environmental Impact Statement lP: Health Physics HSA: Historic Site Assessment IDAP: Incremental Decommissioning Action Plan IOSB: Interim On-site (Radwaste)

Storage Building ISFSI: Independent Spent Fuel Storage Installation LERR: License (e) Event Report LLD: Lower Limit of Detection LTP: License Termination Plan MARSSIM: Multi-Agency Radiation Survey and Site Investigation Manual MDA: Minimum Detectable Activity mph: miles per hour (or MPH)mR/hr: millirem per hour MSL: mean sea level MWe: megawatt -electrical (output)MWt: megawatt -thermal uCi: microcurie (also gxCi, VCi/g (per gram), iCi/ml (per milliliter), JtCi/cc (per cubic centimeter)

NOAA: National Oceanographic and Atmospheric Administration NPDES: National Pollutant Discharge Elimination System NRC: Nuclear Regulatory Commission (Also USNRC)ODCM: Offsite Dose Calculation Manual ODR: Occurrence Description Report OTSG: Once Thru Steam Generator(s)

PAP: Personnel Access Point Revision 1 RSNGS Historical Site Assessment 10 August 2006 Terms, Acronyms, and Abbreviations (Continued)

PASS: Post Accident Sampling System PCP: Process Control Program PDP: Proposed Decommissioning Plan PDO: Potential Deviation from Quality PE: Plant Effluent pCi: picocurie (pCi/l (per liter), pCi/g (per gram))PUDF: Plan for Ultimate Disposition of the Facility OA: Quality Assurance OC: Quality Control RB: Reactor Building (or RCB Reactor Containment Building)RCA: Radiologically Controlled Area RCPRSNPGS:

Radiological Characterization Plan for the Rancho Seco Nuclear Power Generating Station RCRA: Resource Conservation and Recovery-Act RCS: Reactor Coolant System REMP: Radiological Effluent Monitoring Program RP: Radiation Protection RSNGS: Rancho Seco Nuclear Generating Station consisting of an 87 acre Industrial Area containing the nuclear facility and a total site area of 2,480 acres RSSI: Radiological Site Survey Investigation RHUT: Regenerant Holdup Tank(s) (A, B, & C)RWP: Radiation Work Permit SAR: Safety Analysis Report SER: Safety Evaluation Report SMUD: Sacramento Municipal Utility District SUID: Survey Unit Identification Number UFSAR: Updated Final Safety Analysis Report USAEC: United States Atomic Energy Commission (also AEC)Revision 1 RSNGS Historical Site Assessment 11 August 2006 This page intentionally left blank Revision 1 August 2006 RSNGS Historical Site Assessment 12 4.0 PROPERTY IDENTIFICATION 4.1 Facility Characteristics 4.1.1 Licensee Identification (DPR-54)Sacramento Municipal Utility District Rancho Seco Nuclear Generating Station Physical address 6201 S Street, Sacramento, California 95817-1899 Mailing address PO Box 15830, Sacramento, California 95852-1830 4.1.2 Location Rancho Seco Nuclear Generating Station 14440 Twin Cities Rd Herald, California 95638 The property, herein called the site, is located in the southeast part of Sacramento County, state of California and lies either wholly or partly within Sections 27, 28, 29, 32, 33, and 34 of township 6 North, Range 8E. The nuclear reactor unit lies entirely within section 29.The site is approximately 25 miles southeast of Sacramento and 26 miles northeast of Stockton in the central valley of California between the foothills of the Sierra Nevada Mountains to the east and the Pacific Coast range bordering the Pacific Ocean to the west. A map of the facility and location is included as Figure 4.1.The RSNGS site consists of an approximately 87-acre fence-enclosed Industrial Area containing the nuclear facility surrounded by District-owned and District-controlled property totaling 2,480 acres.The District constructed a 30-acre natural gas-fired power plant on the RSNGS site, approximately 2 mile south of the Industrial Area boundary.

Also within the 2,480 acre site are the 560 acre Rancho Seco Reservoir and Recreation Area; a 50 acre solar power (photo-voltaic) electrical generating station; and the 10 acre, 10 CFR Part 72 licensed Independent Spent Fuel Storage Installation (ISFSI).1'The 10 CFR Part 72 licensed ISFSI is independent of the 10 CFR Part 50 licensed facility.Revision 1 RSNGS Historical Site Assessment 13 August 2006 Figure 4.1 RSNGS Historical Site Assessment Revision 1 14 August 2006 4.1.3 Topo~gahy The plant site's rolling terrain is not directly intersected by any streams; however, drainage from higher levels is well defined and intercepts with runoff streams at lower levels. The plant's grade level of approximately 165 feet above MSL allows excellent drainage without danger of flooding.

The elevation of the site acreage varies from 130 feet to 280 feet above MSL and drainage along natural gullies varies from two to six percent. Runoff from the site drains into a seasonal "No -name" creek that is a tributary to Clay creek. Clay creek empties into Hadselville creek. Hadselville creek then empties in turn into: Laguna creek south, Consumnes River, Mokelomne River, Sacramento River, into the Pacific Ocean via the Sacramento River Delta.2 4.1.4 Stratigraphy Information regarding the stratigraphy of the site is taken, in part, from the FSAR [Ref. 9.5].The stratigraphy below the site consists of a basement of Mesozoic and Paleozoic metaphoric rock, overlain with several tertiary and quaternary period formations including:

Recent Alluvium (Qal) consisting of stream deposited gravel, sand, and silt. This material is confined to present drainage courses and ranges in depth from 0 to 5 feet.Older Alluvium (Qalo) consists of old stream and terrace deposits of gravel, sand, and silt. This material covers the flood plains in the southwest portion of the site and ranges in depth from 0 to 10 feet.Arroyo Seco formation (Qas) consists of deposits of well-rounded cobbles, pebbles, and sand derived chiefly from pre-Cretaceous sediments on pediment surfaces.

This formation caps uplands in the eastern portion of the site and ranges in depth from 0 to 15 feet." Laguna formation (T1) consists of sand, silt, and some gravel; may or may not contain clay. Fluviatile deposits are poorly bedded, poorly exposed, and non-andesitic in composition.

This is the predominant formation within the site and ranges in depth from 0 to approximately 130 feet." Mehrten I consists of fluviatile sandstone, siltstone, and conglomerate dominantly of andesitic detritus.

Locally contains horizons of coarse andesitic agglomerate of mudflow origin. This formation has no pre-construction surface exposure and there is little possibility that any construction excavation entered this formation, which has an approximate thickness of 225 feet.2The site information contained in Sections 4.1.3 through 4.2.5.8 is based on the current FSAR and has not been updated to the current date of this document.Revision 1 RSNGS Historical Site Assessment 15 August 2006 Valley Springs formation (Tv) consists of pumice and fine siliceous ash with much greenish-gray clay and some vitreous tuff, glassy quartz sand, conglomerate; commonly well bedded; derived largely from rhyolithic ejectamenta thrown out from the high Sierra Nevada. This formation also has no site surface exposures and an estimated average thickness of 250 feet.4.2 Environmental Characteristics 4.2.1 Geology Information regarding the geology of the site is taken, in part, from the FSAR.Rancho Seco is located about 25 miles southeast of Sacramento California in the low foothills of the Sierra Nevada Mountains.

The site is founded on the Pliocene Laguna Formation and is underlain by an estimated 11500 to 2,000 feet of Tertiary or older sediments deposited on a basement complex of granite to metamorphic rocks. Field exploration included;* 1,552 feet of bucket auger holes logged in detail;* A 602 foot core hole visually and geophysically logged;0 2,016 feet of small-bore hole borings that were logged and from which, soil samples were taken for laboratory analysis; and* Approximately 11,500 feet of geophysical refraction profiles.The resulting data from this exploration strongly indicate a lack of faulting below the Rancho Seco site.4.2.2 Seismology Information regarding the seismology of the site is taken,' in part, from the FSAR.There are no indications of faulting below the site. The nearest fault, located approximately 10 miles to the east of the site, is the Foothill Fault System. This system has been inactive since the Jurassic Period, some 135 million years ago. The nearest active faults, located over 70 miles to the west, are the Hayward and San Andreas.In response to questions by the NRC, prompted by a magnitude 5.7 earthquake on a fault previously believed to be inactive near Oroville, Ca. the District commissioned the reinvestigation of potential seismic activity in the vicinity of the site (Response to NRC questions on Geologic and Seismologic Conditions, 1987 [Ref. 9.14]). The results confirmed the lack of any credible faults closer than the Foothil[ Fault considered in the original licensing documents.

A search of the USGS database for earthquakes-with intensities greater than IV on the modified Mercalli scale (Richter scale 4.0 or larger -Table 4.1) within a 200-mile radius of the plant resulted in 846 such events.Revision 1 RSNGS Historical Site Assessment 16 August 2006 Table 4.1 Magnitude

/ Intensity Comparison Magnitude and Intensity measure different characteristics of earthquakes.

Magnitude measures the energy released at the source of the earthquake.

Magnitude is determined from measurements on seismographs.

Intensity measures the strength of shaking produced by the earthquake at a certain location.

Intensity is determined from effects on people, human structures, and the natural environment.

The following table gives intensities that are typically observed at locations near the epicenter of earthquakes of different magnitudes.

Magnitude Intensity Description I 3.0-3.9 11-111 iotor on ,5.0-5.9 Vi -VII 7.0 and Vill or higher higher U.S. Department of the Interior, U.S. Geological Survey USGS Privacy Statement II Disclaimer II FOIA I I Accessibility This page is brought to you by the Earthquake Hazards Program URL: http://neic.usgs.gov/neis/general/handouts/magvsint.htn-l Contact: NEIC Web Team Last modification:

Friday, 18-Oct-2002 14:34 Revision 1 August 2006 RSNGS Historical Site Assessment 17 The largest event was the 1989 Loma Prieta earthquake (Magnitude 7.1 (7.2 in other literature), Modified Mercalli IX, 160 km distant) and the nearest was a magnitude 4.3, Modified Mercalli V, quake, 45.36 miles (73 km) from the site.Restricting the search criteria to a 50-mile (80.5 km) radius results in only three monitored events.These results, along with the geographical positioning of the site, aerial photos, and mapping of the facility are included in Appendix D.4.2.3 Hydrology Information regarding the hydrology of the site is taken, in part, from the FSAR and the USAR [Ref. 9.6].As described in section 4.1.3 Topography, above, the plant site's rolling terrain is not directly intersected by any streams; however, drainage from higher levels is well defined and intercepts with runoff streams at lower levels. Runoff from the site drains into an un-named"No-Name" creek, which in-turn empties into Clay creek. Clay creek empties into Hadselville creek. Hadselville creek then empties in turn into: Laguna creek south, Consumnes River, Mokelomne River, Sacramento River, into the Pacific Ocean via the Delta.Within recent historical times no flooding or inundation from storms or runoff has occurred within the site boundaries.

It is highly unlikely that the site could be flooded, even with abnormal rainfall intensities.

Since the commencement of operations in 1974, the only significant change in regional land use had been the conversion of several sections of land near the facility from grazing to wine grape production.

An additional change of some note would be the population expansion that has occurred in the communities of Galt and lone, Ca. According to the City of Gait Housing Needs Assessment, Administrative Draft, October 2001, the population of this historically-agricultural community, located between 10 and 15 miles from the site, doubled from 1990 to 2000 and the number of residential properties nearly doubled to almost 6000 units. While notable, the Ione expansion has not been as dramatic.Surveys conducted by the County of Sacramento indicate that the land adjoining the site, within at least a 15-mile radius, will remain primarily for agricultural and grazing use;therefore, the rainfall runoff factors will remain constant and not cause any difference in the hydrological properties of the region.Within this 15-mile radius, seven reservoirs or lakes of note exist. These include small, private impoundments for agricultural use (i.e., Arroyo Seco and Wallace -under 3,000 acre feet) and moderate, municipal reservoirs for recreation and domestic, municipal usage (Comanche and Pardee reservoirs and Lake Amador -up to 435,000 acre feet).4.2.4 Hydrogeology Ground water in the area is found at depths generally greater than 100 feet in the sediments of the Laguna and Mehrten Formations.

The sand and gravel zones of these formations yield water readily to wells predominately west of the facility in the Central Valley. At the site Revision 1 RSNGS Historical Site Assessment 18 August 2006 however, the formations are less permeable, and the Laguna Formation is above the water table; depth to water in the vicinity of the site is approximately 150 feet.Ground water flow is generally to the west. West of the site the flow is affected by a conical depression resulting from the ground water pumping center to the Southwest near the town of Galt, Ca. (Figure 4.2)Water from the Laguna and Mehrten formations is of generally good quality in the vicinity of RSNGS. It is a sodium bicarbonate-type with low total dissolved solids, generally less than 200 ppm. Potable water for RSNGS site comes from four wells producing from the Mehrten formation at a depth interval of 200-350 feet. Two wells are located within the Industrial Area, one well serving the Rancho Seco Reservoir and Recreation Area and one well serving a residence located at the northeastern comer of the site.Studies performed during the initial sighting evaluation and documented in the FSAR, as well as several conducted since the commencement of operations (Geotechnical Investigation for Proposed Evaporation Ponds, ERPT-C0104, Rev. 1, [Ref. 9.12] and the Final Engineering Report Assessment of Spent Fuel Liner Leakage, ERPT-M0221, Rev.0, 1990, [Ref. 9.13]), indicate that the permeability of the site soils result in infiltration rates (from several hundred to several thousand years) that effectively preclude any radiological impact on the aquifer or the closest well to the site by the facility.Revision 1 RSNGS Historical Site Assessment 19 August 2006 Source: Based on measured spring 2000 water level data from Sacramento County Department of Water Resource Contour numbers indicate feet from mean sea level (msl)Credit: Sacramento County 2002 Zone 40 Water Supply Master Plan EIR http://www, saccodwr.org/files/Water/EIRIZ40%205ect%204,7%202Water.

pdf Figure 4.2 Ground Water Contour Map RSNGS Historical Site Assessment 20 Revision 1 August 2006 4.2.5 Meteorology 4.2.5.1 General Climatology The climate of the RSNGS site is generally that of the Great Central Valley of California.

Summers are hot and cloudless and winters are mild. The rainy season occurs between October and May with more than two-thirds of the annual rainfall occurring in December through March. Heavy fog occurs in mid-winter, primarily in December and January, and may last for several days.Incidents of severe weather, such as Tornados and thunderstorms are infrequent.

The most controlling geographical influence on climate results from the mountains, which surround the valley to the west, north, and east. During the winter, storms that pass through the area are moderated by the mountains, which collect much of the precipitation.

The precipitation that does occur in the valley is usually accompanied by south to southeast winds. The cold north and northwest winds pass over the mountains to the north where the air is warmed dynamically by the descent into the valley resulting in comparatively warm, dry winds. A similar condition occurs infrequently in the summer when a steep pressure gradient develops, producing a pronounced heat wave.The Central Valley warms greatly during the day resulting in a marked thermal contrast between the valley and the air over the Pacific Ocean. The Coast Range separates the marine air from the valley air except for a gap through the range formed by the Sacramento and San Joaquin Rivers. The heavy marine air flows through this gap and splits into a northerly flow into the San Joaquin Valley and a southerly flow into the Sacramento Valley.The divergence zone between the two flows usually lies between Stockton and Sacramento near the site. The divergence zone is typically north of the site during the day, resulting in north to northwest winds. As the air in the valley cools, the flow decreases and calm may set in. If the drainage from the Sierra Nevada is sufficient, the winds may shift to southeasterly and increase in speed.During the hottest mid-summer months, light westerly winds may persist all night. During the winter, the synoptic gradients prevail much of the time and the wind trajectories over the Sacramento-Stockton-RSNGS region are reasonably uniform.4.2.5.2 Extreme Winds Wind data from Sacramento Executive Airport from 1951 to 1971 were used to conduct an extreme wind probability distribution approximate to the RSNGS site. Table 4.2 presents the hýghest expected wind speed that will be expected for the indicated recurrence interval.Revision 1 RSNGS Historical Site Assessment 21 August 2006 Table 4.2 Expected Extreme Wind Speeds Return Period (years) Wind speed (mph)50 90!00 101 1000 149 10000 169 The highest recorded average wind speed for Sacramento during the period of July 1877 through December 1989 was 70 mph (recorded in both December 1952 and November 1953).4.2.5.3 Tornados Tornados have been recorded in California but with a frequency of only two per year (National Climatic Summary, 1969). They are generally not severe, and in many cases amount to little more than a whirlwind that may cause damage to trees and light structures.

An examination of newspaper accounts of nine tornados in California indicates that only one may have been accompanied by wind speeds higher than 100 mph.The location of a possible tornado strike can be approximated by a geometrical point. The probability of a tornado occurring at a specific point can be estimated by the principle of geometric probability.

If two tornados per year are used, the return period for RSNGS is approximately 21,855 years. Because the intensity of California tornados is much less than the "classical mid-western types", winds in only one of five of these tornados would be expected to exceed 100 mph.This information is reasonably confirmed by searches conducted of the National Oceanic and Atmospheric Administralion's (NOAA) database which result in the following information.

From 1950 through 1995, California, as a whole, averaged 5 tornados per year. This relates to an average of 0.3 tornados per year per 10,000 square miles.The annual average number of strong-violent (F2-F5) tornados in California for the same period is zero (0).4.2.5.4 Tropical Storms and Hurricanes The possibility of severe storms in the area can be limited to thunder storms and tornados.

A discussion of tropical storms and hurricanes is not applicable to RSNGS.Revision I RSNGS Historical Site Assessment 22 August 2006 4.2.5.5 Precipitation Extremes The precipitation Climatology of the Great Central Valley is characterized by a dry season from June through September and a rainy season from October to May. No precipitation records were taken from RSNGS, but because precipitation is associated with large-scale synoptic systems, the data in Table 4.3 below, taken from the ISFSI FSAR [Ref. 9.19], are believed to be representative of the site.The annual rainfall occurs almost exclusively in the winter months.Table 4.3 Precipitation Climatology Averages (inches)Month Sacramento Stockton January 3.18 2.55 February 2.99 2.46 March 2.36 2.05 April 1.40 1.14 May 0.59 0.44 June 0.1 0.07 July ," 0.01 0.01 August 0.02 0.01 September 0.19- 0.19 October 0.77 0.63 November 1.45 .1.17 December 3.24 2.66 Total. 16.29 13.37 A frequency of occurrence of a given precipitation intensity for Sacramento is presented in Table 4.4 (from the ISFSI FSAR). As stated above, this data is believed representative of the conditions that exist at the site and shows that virtually all of the precipitation falls at a rate of under a quarter inch per hour.Revision 1 RSNGS Historical Site Assessment 23 August 2006

.Table 4.4 Precipitation Intensity Year Intensity (inches/hour) 0.01-0.09 0.10-0.24 0.25-0.49 0.50-0.99 1961 79.5% 17.7% 2.3% 0.5%1962 81.8% 17.0% 0.8% 0.4%1963 80.0% 17.8% 2.2% 0.0%1964 86.2% 11.3% 2.2% 0.3%1965 89.0% 10.0% 1.0% 0.0%Average 83.5% 14.6% 1.7% 0.2%4.2.5.6 Snow and Ice Storms The possibility of severe storms in the area can be limited to thunderstorms and tornados.Snow in the Sacramento area is extremely rare. Most snow that has been observed in the Sacramento Valley occurs in January. Given the lack of significant snowfall in the region, a detailed discussion of snow and ice is not applicable to the RSNGS site.4.2.5.7 Thunderstorms

-Thunderstorms, and associated lighting strike, occur infrequently in the area, with the mean number of days per year with thunderstorm activity ranging between 5 in the Sacramento area to 3 in the Stockton area.4.2.5.8 Restrictive Dilution Conditions (Inversions)

Inversions occur in the Great Valley as a result of cold air advection near the ground or cooling of the earth causing a cooling of the air near the ground. Radiational cooling occurs at night when there are no low clouds. Both types occur at RSNGS with the advection type usually associated with the westerly wind bringing in cool air from the Pacific Ocean.Temperature inversions at the ground can be expected to occur every night during the summer upwards to several hundred feet. These temperature inversions are the result of the flow of cool maritime air in to the area during the late afternoon and evening hours. During the winter, shallow (a few hundred feet) but intense surface inversions can be expected occasionally during the nighttime hours under light wind conditions.

Revision 1 RSNGS Historical Site Assessment 24 August 2006 5.0 HSA METHODOLOGY The methodology used for the RSNGS Historical Site Assessment is that found in NUREG-1575, MARSSIM. As described in MARSSIM, RSNGS, being a NRC licensee has much of the HSA related information within the records management system used to maintain its records throughout its operational history.5.1 Approach and Rationale The primary objective of the HSA records search process was the identification of those events posing a significant probability of impacting the hazardous or radiological characterization of the site. These included system, structure, or area contamination from system failures resulting in airborne releases, liquid spills or releases, or the loss of control over solid material management.

Each incident identified that posed a realistic potential to impact the characterization of the site was further investigated.

This investigation focused on the scope of contaminant sampling and analysis, remedial actions taken to mitigate the situation, and any post-remedial action sampling, survey, and analysis in an attempt to identify the "as left" condition of the incident location.

The records management system provided the source of a vast majority of the.documents inspected.

Also included in the research associated with the development of the HSA were:* Relevant excerpts from written reports and correspondences;

Personnel interviews, including the use of questionnaires, of current, former and retired plant personnel to confirm documented incidents and identify undocumented incidents; and* Site inspection, utilizing historic site drawings, photographs, prints, and diagrams to identify, locate, confirm, and document areas of concern.Information from this research was used in the HSA development, including the compilation of data, evaluation of results, documentation of findings, and the characterization and identification of Areas and Survey Units.Relevant information that becomes available following the publication of the HSA during the characterization and remediation phases of the License Termination Program will be evaluated and documented.

5.2 Documents reviewed In researching the HSA, the records reviewed include:* License and Technical Specification reports;* Annual operational and environmental reports;* Environmental investigations performed by independent entities;* Regulatory actions against the site;Revision 1 RSNGS Historical Site Assessment 25 August 2006

Documentation from interviews conducted with currently employed and retired/separated site personnel;

Radiological control surveys associated with. identified events;* Site inspection and surveillance documents associated with identified events;* Federal, State and local regulations;

Regulatory and Industry guidance documents;

Annual Environmental and Operational documents;

License Event Reports (LERs);* Occurrence Description Reports (ODRs);* Quality departure documents, including Potential Deviations from Quality (PDQ)and Deviation from Quality (DQ);* Radiological and environmental survey documents;" Routine radioactive release reports;" Non-routine reports provided to the NRC under the provisions of the facility's technical specifications, 10 CFR Part 20, and 10 CFR Part 50;" Plant incident or condition reports;" Radiological assessments; and" Quality control/Quality Assurance finding documents.

Records maintained to satisfy the requirements of 10 CFR Part 50.75(g)(1) provided a major source of documentation for the HSA records review process.Appendix A contains a summary of the details found in the documents reviewed.

A brief incident description, radiological implications, and finding synopsis, are included.5.3 Site Reconnaissance As provided for in MARSSIM Section 3.5, a formal site reconnaissance was not performed, based on the continuous occupancy of the site by the licensee, the detailed information available through the records, and the personnel interviews performed.

Appropriate site reconnaissance has been performed to verify locations and current conditions of items or issues discovered during these investigations.

5.4 Personnel Interviews Between August 2001 and December 2002, approximately 150 observations were noted from the individuals contacted in the HSA questionnaire program. These individuals represented a combination of current and past employees, primarily from the operations and radiation protection staffs. These two groups were chosen due to their knowledge of and association with the systems and source terms being investigated for this assessment.

Revision 1 RSNGS Historical Site Assessment 26 August 2006 The personnel surveys included a combination of questionnaires completed by a majority of the participants as well as individual and group interviews "with several of the participants.

With few exceptions, the personnel observations were corroborated by either the observations of other interviewees or documentation discovered during the. records search.Table 5.1 contains a brief summary of the survey results showing the number of observations recorded for the various general areas identified.

Appendix B contains copies of the questionnaire and a response summary sheet.Table 5.1 Personnel Observations Summary General Area of Observation Number of_______________________

Observations Auxiliary Boiler, pad, drains sump 10 Auxiliary Building 7"B" Warehouse 4 Barrel Farm (Waste Storage Area) 4 Balance of Plant (BOP) 14 Building Maintenance/Machine 4 Shop"C" Warehouse 2 Circulating Water Basins 16 surrounding area _ _ _Fabrication and Weld Shops 2 Building Contractor Fab Shop* 8"GRS" Warehouse t I Interim Onsite Storage Building (IOSB)Non-Radiological Observations 4 Plant Effluent 4 Quonset. Hut 11 Retention Basin 2 RHUT's 13 Storm Drains 5.Training and Records Laboratory 1 Tank Farm 13 Tool Room 1 Turbine Building 9 Tritium Evaporator

-3 Training Simulator Building 1 (offsite)

"Upper/Outer" Storage Yard 1 Sewer Plant 1 RSNGS Hifstorical Site Assessment Revision 1 August 2006 27 5.5 Historical Con'struction Photograph Review Collections of historical construction photographs were reviewed to assess their contribution to this HSA. A selection of construction photographs is included as Appendix E. Also, additional original construction photographs are contained in the Construction Report issued by Bechtel Corporation

[Ref. 9.20].I Revision 1 August 2006 RSNGS Historical Site Assessment 28 6.0 OPERATIONAL HISTORY The following summary of the facility's history was determined through a review of site records, documents and personnel interviews.

6.1 Introduction The RSNGS was issued its 10 CFR Part 50 operating license (DPR-54) on August 16, 1974 and attained initial criticality one month later, on September 16, 1974. The facility became commercial on April 18, 1975.The facility is described in multiple licensing documents including: " "Rancho Seco Nuclear Generating Station Unit 1 Defueled Safety Analysis Report" [Ref. 9.7]; and" US Nuclear Regulatory Commission (formerly the US Atomic Energy Commission), Safety Evaluation by the Directorate of Licensing, US Atomic Energy Commission, in the matter of Sacramento Municipal Utility District Rancho Seco Nuclear Generating Station, Unit 1, " Docket 50-312 (SER) [Ref.9.8].RSNGS had a pressurized water reactor (PWR) designed and constructed by Bechtel Power Corporation with its nuclear steam supply system (NSSS), rated at 2,770-MWt, 913 MWe, provided by Babcock and Wilcox. Condenser cooling and make-up water was provided via the Folsom-South canal, constructed by the Bureau of Reclamation.

The RSNGS site is located in southern Sacramento County, California, approximately 25 miles southeast of Sacramento and 26 miles northeast of Stockton.

The site is located on 2,480 acres entirely owned by the District.

The facility is located between the Sierra Nevada Mountains to the east, and the Pacific Coast range bordering the Pacific Ocean to the west.The rural area is used almost entirely for agricultural purposes including row and silage crops, cattle graze land, and in recent years, wine grape production.

Within the five-mile radius of the site, there are no significant tourist attractions or variations in population.

The nearest population area is approximately 6.5 miles from the site while the closest substantial populations

(>20,000) are Gait, and Lodi, CA. at 10 and 17 miles from the site, respectively.

The main access to the site is State Highway 104 (Twin Cities Road), which runs from highway 99 (just north of Galt, CA) in the west, to State Highway 88 (just east of lone, CA)to the east.After approximately 15 years of operation, RSNGS was shut down for the last time on June 7, 1989, after passage of a non-binding referendum by the voters of Sacramento County recommending the District discontinue operation of RSNGS.The reactor was completely defueled on December 8, 1989.Unable to attract a buyer for the facility, the District formally notified the U.S. Nuclear Regulatory Commission (NRC) of its intent to permanently shut down the facility, requesting a possession-only license on April 26, 1990.Revision 1 RSNGS Historical Site Assessment 29 August 2006 As noted in the "Rancho Seco Nuclear Generating Station Proposed Decommissioning Plan" (PDP) [Ref. 9.9], RSNGS operated for approximately 2,149 effective full power days (seven fuel cycles), over the course of its operating lifetime.A summary of the operational history is provided in Table 6.1 below.TABLE 6.1 Operational History -RSNGS Date Event Oct. 1968 Received construction permit Mar. 1969 Commenced site preparation/construction Aug. 1974 Operating License (OL)- issued Aug. 1974 Completed initial fuel loading Sept. 1974 Achieved initial criticality Apr. 1975 Commenced commercial operations Jun. 1975 -Oct Two unplanned outages to repair material deficiencies.

Full power achieved in Mar. 1976. Full power regained in Oct. after 7-month stator coil outage.1977 8 months of full power operations (75% capacity factor Jul-Dec.)Nov. 1978 Completed cycle three refueling in 35 days Aug. 1980 Turbine rotor failure resolved Jun. 1982 Frequent electrical inverter trip resolution achieved Apr. 1983 Turbine oil system associated trip issues resolved Aug. 1984 Steam Generator repairs and Aux. Feed water modification outage Dec 1985 Extended plant shutdown resulting from overcooling unusual event Extended plant shutdown for post TMI-mod installation, emergency Mar. 1986-88 feed water system modifications, detailed system analysis and test program implemented, and installation of two additional backup diesel generators..

Resolved feed water transient issue, completed restart testing. Public Jun 1989 referendum voted to have SMUD discontinue operation of RSNGS.Plant shuts down for last time on June 7, 1989.SMUD notifies NRC of its intent to seek a decommissioning Aug. 1989 amendment to its license.Revision 1 August 2006 RSNGS Historical Site Assessment 30 TABLE 6.1 Operational History -RSNGS (Continued)

Date Event Sept. 1989 District fails in its attempts to sell RSNGS or convert to non-nuclear operation.

Dec. 1989 Reactor defueling completed on December 8, 1989.Jul. 1990 SMUD submits the Plan for Ultimate Disposition of the Facility in response to NRC request.May- SMUD submits RSNGS Proposed Decommissioning Plan (PDP)1991 October -Board approves California Environmental Quality Act"Negative Declaration" for PDP (State clearinghouse number (SCH#) 91062072)Mar. 1992 RSNGS OL amended to Possession Only Mar. 1995 NRC approves PDP January -SMUD Board approves Incremental Decommissioning Action Plan (IDAP for 1997 through 1999) and California Environmental Quality Act "Subsequent Negative Declaration" 1997 (SCH# 96112047) for IDAP Post Shutdown Decommissioning Activities Report (PSDAR)Submitted IAW 10 CFR Part 50.82 (PSDAR supercedes the PDP)January 1999 -SMUD Board approves IDAP -Rev. #1 (continue 1999-2000 decommissioning through license termination) and CEQA"'Subsequent Negative Declaration" for IDAP Rev. I1 (SCH#99042092)

June 30, 2000 -NRC issued SMUD a 10 CFR Part 72 license to store Jun. 2000 RSNGS's spent nuclear fuel atthe ISFSI Spent fuel transfer to ISFSI complete -TS amendments.

129 and 130 take affect- precludes SF possession on the 10 CFR Part 50 licensed AIug. 2002 facility and eliminates the need for an Operations Shift Supervisor or Certified Fuel Handlers Oct 2002 TS amend. 131 takes effect eliminating security plan requirements from the 10 CFR Part 50 licensed facility RSNGS Historical Site Assessment Revision 1 August 2006 31 The fact that the plant was shut do-xn years before the expiratien of its operating license resulted is several significant impacts, two of which include: " The District's inability to comply with the requirements of 10 CFR Part 50.75 regarding the submission of a preliminary decommissioning plan five years prior to the cessation of operations; and* A significant shortage of funds within the decommissioning trust fund.6.2 Decommissioning Plan Chronology Prompted by a NRC staff request, the "Plan for Ultimate Disposition of the Facility" (PUDF), was submitted in July 1990 [Ref. 9.10]. The original intent of the licensee, as outlined in this document, was to decommission RSNGS using the SAFSTOR -Deferred DECON alternative.

This alternative was to include Custodial, as well as Hardened, -SAFSTOR applications as generally defined in the "Final Generic Environmental Impact Statement on Decommissioning of Nuclear Facilities," NUREG-0586, August 1988 (GEIS)[Ref. 9.11]. Dismantlement following the SAFSTOR period was estimated to occur in the 2008 to 2012 time frame.On May 20, 1991, the District submitted the PDP for the Rancho Seco facility, dated April 15, 1991, for NRC approval.

The District subsequently submitted supplements to the PDP for review dated April 15, August 6, & August 3!, 1992; January 7, April 7, & April 19, 1993;and March 23, April 28, July 26, & October 26, 1994. After an extensive NRC staff review, the PDP was approved on March 20, 1995.Simultaneous with this review was the amendment of the District's Operating license (DPR-54), to reflect a possession-only authorization ori March 17, 1992 and the NRC staff s review of the associated safety evaluation and environmental assessment of the impacts associated with the decommissioning of RSNGS resulted an initial Finding Of No Significant Impact (FONSI), issued on June 16, 1993.Also occurring during this period was the decision by the District to commence, in an incremental manner, the dismantlement of the site during the Custodial SAFSTOR period.In 1991, the District Board of Directors approved the negative declaration prepared for the original PDP (Resolution No. 91-10. 18) on October 17, 1991. (State Clearinghouse No.91062072)In January 1997, the District Board of Directors approved (Resolution 97-01-07) a significant revision to the Decommissioning Plan titled "Incremental Decommissioning Action Plan" (IDAP) and a subsequent negative declaration regarding the potential environmental impacts.(State Clearinghouse No. 96112047)In April of 1999, the District Board of Directors approved revisions to the IDAP (IDAP -RI) accelerating the schedule of the decommissioning effort. (State Clearinghouse No.99042092)In accordance with the applicable provisions of the California Environmental Quality Act (CEQA), the District prepared and circulated the studies and evaluations necessary to support Revision 1 RSNGS Historical Site Assessment 32 August 2006 the subsequent negative declarations associated with the PDP, IDAP, and IDAP -RI. This included multiple public meetings convened by the Distridt and the NRC.6.3 Regulatory Overview The RSNGS has been, and continues to be, closely monitored in a highly regulated environment.

Regulatory oversight is provided by an extensive collection of Federal, State, Local, and licensee personnel in addition to non-regulatory industrial peer groups and local stakeholders.

This hierarchy of oversight has carried out its various responsibilities during the sighting, licensing, construction, operations, and decommissioning phases of the plant's life and includes:* United States Atomic Energy Commission (AEC);* United States Nuclear Regulatory Commission;

United States Environmental Protection Agency (EPA);* US Army Corps. Of Engineers

-Bureau of Reclamation;

California Department of Health Services -- Radiological Health Branch;* California Department of Toxic Substance Control (DTSC);* California Regional Water Quality Control Board;* State Water Resources Control Board;* California Department of Fish and Game;* Sacramento Metropolitan Air Quality Management District;* Local/County Governments; and* District Regulatory affairs/licensing.

6.3.1 Permits and Licenses Permits, issued to the District in association with the construction, operation, and dismantlement of RSNGS, are summarized in Table 6.2 Revision I RSNGS Historical Site Assessment 33 August 2006 TABLE 6.2 Licenses and Permits Issuing Agency Permit/License Number USAEC CPPR-56 Construction Permit -Pressurized Water Nuclear Plant USAEC SNM-1333 SNM License USAEC 04-14866-01 Byproduct Materials License California Department of Health -Radiation Health Section 2239-34 Radioactive Materials License USAEC #DPR-54 Possession Only License (POL)USAEC #DPR-54 Facility Operating License (FOL issued 8/16/74)_California Regional Water Quality Control Board # CA0004758 NPDES permit California Regional Water Quality Control Board Annual order renewal Waste Discharge Order California Department of Health -ELAP 1681 (Environmental Lab analysis permit) .County of Sacramento

-Air Pollution Control District #292 Permit to operate Steam Boiler #3677 (E-365)County of Sacramento

-Air Pollution Control District #293 Permit to operate Steam Boiler #3680 (E-360)County of Sacramento

-Air Pollution Control District #294 Permit to operate Diesel Generator (G866A)County of Sacramento

-Air Pollution Control District #295 Permit to operate Diesel Generator (G866B)County of Sacramento

-Air Pollution Control District #7731 Permit to operate Diesel Generator (G100A)County of Sacramento

-Air Pollution Control District #7732 Permit to operate Diesel Generator (GiOOB)County of Sacramento

-Air Pollution Control District #4175 Permit to operate Gasoline Dispensing Facility County of Sacramento

-- Air Pollution Control District None Permit to operate Steam Boiler V-200 Reactor Pressure Vessel Sacramento Regional County Sanitation District #LWH-5/98 Class II discharge permit RSNGS Historical Site Assessment Revision 1 August 2006 34 TABLE 6.2 (continued)

Licenses and Permits Issuing Agency Permit/license number State of California None Department of Public Health Laboratory Services Sanitation and Radiation Laboratory.

Non-Commercial Water Laboratory.

Sacramento County #232 Health Department

-Environmental Health Branch Non-Community Water System Permit Sacramento County #302 Health Department

-Environmental Health Branch Non-Community Water System Permit Sacramento.Metropolitan Air Quality Management District 13918 & 13919 (Formerly

-County of Sacramento, Air Pollution Control District)Operation of abrasive blasting booth and bag house exhaust vent Sacramento -Metropolitan Air Quality Management District 11345 Operation of stand-by diesel driven fire pump -Sacramento'Metropolitan Air Quality Management District -11344 Operation of 80 horse power Diesel back-up electrical generator Sacramento Metropolitan Air Quality Management District 13392 Operation of gasoline storage and dispensing station (One 4000 gallon tank with one nozzle)Sacramento Metropolitan Air Quality Management District 13833 & 13834 Operation of unconfined -abrasive blaster and bag house exhaust vent Sacramento Metropolitan Air Quality Management District 13769 & 13770 Operation of abrasive blasting booth and bag house exhaust vent Sacramento Metropolitan Air Quality Management District 11343 Operation of stand-by air compressor (Gasoline driven) 'State of California Agricultural

& Services Agency, Department of Industrial Relation, 2.6.921.84 Division of Industrial Safety Operate bridge crane (TDI diesel cranes) -Load down rated State of California 2.6.922.84 Agricultural

& Services Agency, Department of Industrial Relation, Division of Industrial Safety Operate bridge crane (TDI diesel cranes) -Load down rated State of California 6.25.1249.85 Agricultural

& Services Agency, Department of Industrial Relation, Division of Industrial Safety Operate bridge crane (IOSB crane No. Y-1 12)RSNGS Historical Site Assessment Revision 1.August 2006 35 TABLE 6.2 (continued)

Licenses and Permits State of California 7955 Department of Industrial Relations Division of Occupational Safety and Health Operation of Auxiliary Building grade level monorail crane No. A-1 State of California 8159 Department of Industrial Relations Division of Occupational Safety and Health Operation of Reactor Building polar crane No. Y-204A State of California 8013 Department of Industrial Relations Division of Occupational Safety and Health Operation of Turbine Building gantry crane No. Y-304 State of Washington 6170 Department of Social and Health Services Disposal site use permit Cooling tower transite rcmoval /Bechtel building asbestos removal Provided by permits contractor State of California Various Department of Industrial relations Pressure vessel Permits 6.4 Waste Handling Procedures Waste materials generated at RSNGS are generally described as radioactive, hazardous, mixed (radioactive/hazardous), universal, or non-regulated.

To ensure the conformance with prescribed regulatory requirements, waste handling evolutions are controlled thuough various administrative and operational procedures.

6.4.1 Process Control Program (PCP)The PCP established a program to provide the District and regulators with a reasonable assurance that the radioactive wastes generated at the facility are properly classified, characterized, processed, packaged, manifested, marked, labeled and transported in accordance with the wide spectrum of regulations governing these activities.

6.4.2 Rancho Seco Administrative Procedures (RSAP)RSAP's provide general departmental guidance in the control of various activities within the facility including those associated with radioactive and hazardous material/waste handling.I RSNGS Historical Site Assessment Revision 1 August 2006 36 6.4.3 Radiation Control Manual (RCM)The RCM provides implementing procedures for the control of radioactive material including training requirements, material receipt procedures, and controls for the release of personnel and materials from the controlled area.6.4.4 Radwaste Control Manual (RWCM)The RWCM provides implementing procedures for the management of radioactive waste generated at the RSNGS including material receipts, waste classification, container selection, waste-stream specific processing procedures and characterization verifications.

6.4.5 Chemistry Department Procedures Manual These procedures include chemical controls, off-site dose calculation, and radioactive effluent control implementing procedures.

6.4.6 Surveillance Procedures (SP)SP's are used to document the performance of tests to demonstrate the effectiveness and efficiency of the various implementing procedures and performance of equipment and personnel activities associated with the waste management program.6.5 Current Site Usage RSNGS was shut down on June 7, 1989.6.5.1 Description of Operations Current operations, post fuel transfer to the ISFSI, center on the administrative, technical and physical tasks associated with the dismantlement of the RSNGS.In August 2002, the transfer of spent fuel from the spent fuel pool to the ISFSI was completed and RSNGS transitioned into the Defueled Technical Specifications, greatly reducing the procedural and operational controls required at the facility..

6.5.2 Preliminary Site Characterization The initial characterization of the RSNGS site resulted from the review and evaluation of surveys and evaluations previously conducted to determine the extent and nature of residual contamination.

In accordance with the guidance of MARSSIM, this initial site characterization (as to the Impacted or Non-Impacted nature of the site) began in 2001 and was completed in 2002. The HSA including the initial site characterization is the product of the evaluations and investigation necessary to define the current condition at the site and assign preliminary Area classifications.

This effort also addressed the hazardous material and"state-only" regulated material at the site that may impact future remediation/dismantlement.

Revision 1 RSNGS Historical Site Assessment 37 August 2006 6.6 Site Dismantlement 6.6.1 Dismantlement activities within the Power Block As of January 2003, the decommissioning project has removed virtually all (with the exception of imbedded or buried piping) of the secondary plant systems including: " Main Steam;* Auxiliary Steam;" Main Feed Water;" Main Condensate and Make-up;* Main Circulating Water Pumps;* Main turbine and Condenser; and o The vast majority of the support systems located in the Turbine Building.Within the AuxiliaryBuildig, a majority of the systems have been removed. Spent Fuel Building dismantlement began in October 2002.Within the Reactor Containment Building, significant progress has been made including removal of all four reactor coolant pumps and motors, a substantial portion of the reactor coolant system, reactor building ventilation system, and support/electrical/mechanical systems.6.6.2 Dismantlement activities outside the Power Block Dismantlement activities outside of the facility power block are directed at the removal of temporary buildings and structures and are being carried out in accordance with standard site procedures for the release of potentially contaminated materials and equipment.'

Final Status Survey's will be conducted of thf- "footprintt" left, from these structures' dismantlement to verify that no residual contamination above the established derived concentration guideline level (DCGL) will remain following license termination.

6.7 Radiological Sources The majority of regulated waste resulting from the decommissioning of the RSNGS will result from the radiological contamination of plant structures and equipment.

The primary source of this contamination was the operation of the facility nuclear reactor and its associated support systems. Based on information developed for the IDAP (section 3.1.3), the radiological inventory of the facility is described in the following sections.6.7.1 Spent Fuel The largest single contributor to the radioactive inventory at the facility was spent fuel.Based on estimates performed in 1989, 140,800,000 curies, consisting of primarily

(-70%)Cs-137, Pr-144, Ce-144, Ba-137m, Sr-90, Y-90, Pm-147, and Pu-241 remain. This will decay to approximately 39,630,000 curies by 2009 with Cs-137, Ba-137m, Sr-90, Y-90, and Pu-241 representing over 97% of the remaining activity.Revision 1 RSNGS Historical Site Assessment 38 August 2006 6.7.2 Irradiated Hardware Non-Fuel contributors to the radiological inventory, estimated at approximately 95,000 curies of primarily

(>99%) Co-60, Fe-55, and Ni-63, include:* Orifice rod assemblies (ORA's);* Burnable poison rod assemblies (BPRA's);* Retainer assemblies (RA's); and* Incore instruments.

The ORA's, BPRA's, and RA's were transferred to the ISFSI, along with the spent fuel. The incore instruments were sectioned for shielded storage pending transfer to the ISFSI. The activity associated with these irradiated components will decay to under 9,000 Ci of Co-60 and Ni-63 by 2009.6.7.3 Reactor Vessel and Internals As of May 1, 2003, approximatdly 99,500 curies of primarily

(>61%>Co-60, comprised of reactor pressure vessel internals and the reactor-pressure vessel, are contained within the primary shield wall [Ref. 9.21], 6.7.4 Plant Systems Systems internally contaminated by the operation of the RSNGS have been characterized repeatedly during plant operations.

The most substantial of these characterizations was performed in 1984 by Pacific Northwest Laboratory (PNL-1546, 1984) [Ref. 9.22] showing an estimated 4,500,curies resulting primarily of (>88%) Fe-55, Co-58, Ni-63, and Co-60.6.7.5 Industrial Area Contamination Several areas within the Industrial Area have been identified as having been radiologically impacted by the operation of the' facility including:

Retention Basins;* Tank Farm;* Barrel Farm;* Regenerant Hold Up Tanks (RHUT's);* Storm Drains;* Oily Water Separator;

Cooling Tower Basins; and* Turbine Building drains and sumps.Revision 1 RSNGS Historical Site Assessment 39 August 2006 6.7.6 Non-Industrial Area Contamination Four locations outside of the Industrial Area have historically had radionuclide concentrations detected above background.

6.7.6.1 Discharge Canal Sediment The plant discharge canal sediment has shown detectable concentrations of licensed radioactive material resulting from 10 CFR Part 20.2001 (a)(3) authorized radioactive liquid releases.

This release path has been the subject of numerous studies by the facility staff as well as the Lawrence Livermore National Laboratory (LLNL) and is routinely monitored via the Radiological Environmental Monitoring Program. As discussed in the PDP, the most recent of the LLNL studies (UCRL-ID-106111, November 1990) reported maximum radioactive sediment concentrations of 1.47 pCi/g Co-60 (April 1989), 1.20 pCi/g Cs-134 (January 1989), and 11.00 pCi/g Cs-137 (January 1989) at points within 1,640 feet (0.5 kilometer) of the plant effluent discharge point (0.3 km for January 1989 sampling, 0.5 km for April 1989 sampling).

Current (March 1, 2004) concentrations can be estimated to be < 0.207 pCi/g Co-60, 0.007 pCi/g Cs-134, and 7.74 pCi/g Cs-137 (based on the radioactive decay of the 1989 results).Washout and other transport mechanisms will have also affected the concentrations of radioactive material in the effluent discharge path. RSNGS will update the status of this source term as additional studies are completed.

Oak Ridge National Laboratory also evaluated the environmental impact- of the authorized radioactive liquid releases fcr the NRC. This evaluation was applied to both onsite and offsite locations.

The results of this evaluation are documented in NUREG/CR-4286, Evaluation of Radioactive Liquid Effluent Releases From the Rancho Seco Nuclear Power Plant [Ref. 9.15].As part of the Radiological Environmental Monitoring Program and reported to the NRC in the 2002 Annual Radiological Environmental Operating Report [Ref. 9.16], 24 samples of sediment were collected from the discharge canal and the Clay/Hadselville/Laguna Creeks during 2002. Gamma spectrometry analysis of these samples indicated the presence of Cs-137 in the range of 0.0 17 to 0.604 pCi/g with a riiean of 0.111 pCi/g and Co-60 in the range of 0.008 to 0.035-pCi/g with a mean of 0.021 pCi/g.6.7.6.2 Discharge Canal Soil During plant operation and during the period of authorized radioactive liquid releases, discharge canal sediment was dredged from the canal and deposited as a band adjacent to the canal. Because the discharge canal sediment was known to contain radioactive materials of plant origin, sampling of the soil adjacent to the discharge canal was added to the Radiological Environmental Monitoring Program. As reported to the NRC in the 2002 Arnual Radiological Environmental Operating Report, eight soil samples were collected from this area. Cs-137 was identified in seven out of eight of these samples at a concentration range of 0.042 to 0.266 pCi/g.Revision 1 RSNGS Historical Site Assessment 40 August 2006 6.7.6.3 Depression Area Soil The depression area is an onsite location adjacent to "No Name" Creek. The discharge canal, discussed above, flows into "No Name" Creek. On occasion and during periods of authorized radioactive liquid releases, "No Name" Creek overflowed and collected in the depression area. Because of this, sampling of the soil in the depression area was added to the Radiological Environmental Monitoring Program. As reported to the NRC in the 2002 Annual Radiological Environmental Operating Report, 14 soil samples were collected from this area. Cs-137 was identified in 12 of these 14 samples at a concentration range of 0.070 to 48.15 pCi/g. Cs-134 was identified in two samples at a concentration range of 0.060 to 0.177 pCi/g. Co-60 was identified in six samples at a concentration range of 0.086 to 1.10 pCi/g.6.7.6.4 Storm Drain Outfall The Radiological Environmental Monitoring Program has routinely identified low levels of radioactive materials of potential plant origin in soil samples taken at storm drain locations.

As reported to the NRC in the 2002 Annual Radiological Environmental Operating Report, 30 soil samples were collected from 15 storm drain outfall locations during 2002. Gamma spectrometry analysis of these samples indicated the presence of Cs-137 in the range of 0.013 to 0.102 pCi/g with a mean of 0.043 pCi/g and Mn-54 in one sample at a concentration of 0.007 pCi/g.During the fourth quarter of 2000, Shonka Research Associates, Inc. (SRA) conducted detailed surveys of selected areas outside of the Industrial Area. These surveys were conducted to support consideration of an area south of the Industrial Area proposed for the Cosumnes Power Plant (CPP) to be constructed on the RSNGS site. The surveys also determined the boundary of any Impacted Areas and determined background survey values for comparison to Impacted Area values. These surveys included scan surveys conducted using the Subsurface Multi-Spectral Contamination Monitor (SMCM) system developed by SRA, fixed point in situ NaI(TI) spectroscopy measurements and soil sampling for laboratory analysis.

To manage the surveys, the site was divided into twelve survey areas. Non-Impacted Areas required .10% areal scan surveys and Non-Impacted Areas bounding Impacted Areas required 50% areal scan surveys.The final report on these surveys noted that due to several factors, including the marshy conditions of the fields to the south of the plant, several in situ sample points had to be relocated.

According to the study's authors, this relocated configuration represented the best combination of complete west-east coverage along the storm drain outfall area to the south of the plant.The SMCM scan and the in situ measurement survey results for the outfall area immediately south of the Industrial Area and for the proposed CPP location showed no evidence of plant-derived contaminants in these areas. Cs-137 MDCsfor the SMCM scans of these areas ranged from 0.26 to 0.77 pCi/g and for in situ measurements from 0.31 to 0.40 pCi/g. Two out of five soil samples from these areas tested positive for Cs-137 at a range of 0.03 to 0.30 pCi/g with an analysis MDA of 0.03 pCi/g.NUREG/CR-4286 established Cs-137 background concentrations in the vicinity of RSNGS.Four locations, at distances of 4 to 10 miles from RSNGS and lying approximately north, Revision 1 RSNGS Historical Site Assessment 41 August 2006 south, east and west of the site. The average concentration of Cs-137 in these locations was 0.41 pCi/g. Decaying this average value from December 1984 (the approximate sampling date for NUREG/CR-4286) to December 2002 gives a background concentration of 0.27 pCi/g.6.7.6.5 Comparison of Soil Concentrations with NRC Screening DCGLs As discussed above, Mn-54, Co-60, Cs-134 and Cs-137 have been identified at concentrations above background in four locations outside of the Industrial Area. On December 7, 1999 the NRC published scteening DCGL values in the Federal Register [Ref.9.18] for various common radionuclides.

These screening DCGL values may be used to evaluate the significance of the soil contamination found outside of the Industrial Area.The published NRC generic screening DCGL values are as follows: Mn-54 15 pCi/g Co-60 3.8 pCi,'g Cs-134 5.7 pCi/g Cs-137 I IpCi/g Based on these values, the discharge cana! sediment, the discharge canal soil and the rtorm drain outfall soil will likely not exceed site-specific DCGL values. The depression area soil does exceed the NRC screening DCGL. values. However, it must be compared with site-specific DCGL values developed for surface soils before determination if remediation is necessary.

6.8 Waste Stream Description 6.8.1 Hazardous Materials/Wastes The RSNGS site contains a variety of hazardous materials.

The use, storage, handling, and disposal of these materials are controlled through the same procedures and programs used during the operation of the facility.

In addition to the material management programs in place, the District complies with the OSHA Hazard Communication Standard (29 CFR Part 1910.120) that requires al employers to provide information to its employees about the hazardous substances that they may come into contact with. This is accomplished through the District's Hazard Communication Program that includes training, labeling, other forms of warning, and the availability of Material Safety Data Sheets (MSDS). The District is not abandoning the site, nor do they intend to discontinue the possession or use of hazardous materials or any permits associated with their use. Therefore, the review of hazardous material events for this HSA has not been performed in the same detail as would be done for a site that is to have an unrestricted release from the aspect of hazardous materials.

6.8.1.1 Universal Waste Universal waste means any of the following hazardous wastes that are managed under the universal waste requirements of 40 CFR Part 273: Revision 1 RSNGS Historical Site Assessment 42 August 2006

" Batteries, as described in 40 CFR Part 273.2ý..." Pesticides as described in 40 CFR Part 273.3; and" Thermostats as described in 40 CFR Part 273.4.Additionally, in accordance with California regulatory requirements, "the hazardous wastes listed in this section are exempt from the management requirements of chapter 6.5 of division 20 of the California Health and Safety Code and its implementing regulations except as specified in chapter 23 and, therefore, are not fully regulated as hazardous waste. The wastes listed in this section are subject to regulation under chapter 23 and shall be known as"universal waste."* Batteries as described in section CCR 66273.2;* Thermostats as described in section CCR 6627314;* Lamps as described in section CCR 66273.5;* Cathode ray tube material as described in CCR 66273.6;* Aerosol cans as specified in Health and Safety Code section 25201.16;* Mercury-containing motor vehicle light switches as specified in Health and Safety Code section 25214.5 (MOOl Wastes) and motor vehicles that contain such switches, as described in section 66273.7.1);

Non-automotive mercury switches'and products that contain such switches (including, but not limited to, M002 Wastes), as described in section 66273.7.2; Mercury-containing pressure or vacuum gauges, as described in section 66273.7.4;

Mercury counterweights and. dampers, as described in section 66273.7.6;

Mercury thermometers, as described in section 66273.7.7;

Mercury dilators and weighted tubing, as described in section 66273.7.8;

Mercury-containing rubber flooring, as described in section 66273.7.9; and* Mercury gas flow regulators, as described in section 66273.7.10.

6.8.1.2 RCRA Waste The California DTSC and EPA regulate the packaging, storage, processing and disposal of listed or characteristic waste materials.

RSNGS must demonstrate compliance with both the federal EPA and State program requirements.

Material at RSNGS in this category include:* Polychlorinated Biphenyls (PCBs);* Asbestos-Containing Material (ACM);* Laboratory solvents and reagents;* Chrome containing waste materials; Revision 1 RSNGS Historical Site Assessment 43 August 2006

Lead waste;* Mercury waste from instrumentation;

Cadmium waste;* Corrosive waste from laboratory and cleaning processes;

Spent aerosol cans;* Ignitable waste from Laboratory and maintenance activities; and* Paint related waste solvents from maintenance activities.

6.8.1.3 Mixed Waste Mixed wastes are those wastes regulated by the EPA or equivalent state agency, that are also contaminated with radioactive material.

At RSNGS, these wastes include," Mercury from radioactive system sampling or monitoring instrumentation;

Chromium containing radioactive air filters generated during decommissioning;" Radiologically contaminated solvent from the laboratory and painting and decontamination processes; and" Radiologically contaminated lead from shielding and paint.6.8.2 Low Level Radioactive Waste (LLRW)Low level radioactive waste means those waste materials contaminated with iadioactive material.

LLRW is collected, characterized, classified, packaged and shipped for either processing or disposal at appropriately licensed facilities.

Between 1974 and 1990, RSNGS made 459 LLRW shipments in support of facility operations.

309 dry solid shipments

-147,000 ft 3 150 bulk liquid shipments

-458,000 gals. (Prior to the discontinuation of liquid waste shipments in 1980).After the station's shut down in 1989, the site made only 8 waste shipments totaling less than 4,500 ft 3 between 1990 and 1992 and did not ship radwaste again until 1997 when dismantlement activities in the Turbine building commenced.

The original decommissioning waste volume estimate, based on the 1991 PDP, was estimated to be approximately 200,000 ft.This material can include: " Dry Active Waste (DAW) -paper, plastic, glass, wood, used PPE, scrap metal, floor sweeping, etc.;" Contaminated asbestos insulation material;Revision 1 RSNGS Historical Site Assessment 44 A.ugust 2006

Soil and soil like debris including rubblized concrete and asphalt from various site yard areas;* Equipment, tanks, pumps, motors, generator, and other metal components;

Sludge's -organic and inorganic solids from tanks, pipes, and pumps; and* Charcoal -contaminated filter media used to filter liquid process system and ventilation systems.Since the commencement of incremental decommissioning in 1997, several changes to the volume estimates and inventories have been made as well as significant progress in the dismantlement and disposal of wastes. Spanning the period 1997 to 1999, the successful incremental phase of the decommissioning project demonstrated that decommissioning could be effectively undertaken by completing the dismantlement and disposal of the secondary system at a cost avoidance of approximately 42 million dollars over what had been estimated.

This success provided the basis for the Board's approval of full scale decommissioning, which commenced in 2000.The progress of the decommissioning program to date (December 31, 2003) and the revised projection of remaining waste volumes are summarized below.Class A* Shipped to date -190,000 ft 3 o Processors

-59,000 ft 3 o Disposal-131,000 f-* Remaining-123,274 f 3 Class B* Shipped to Date -none* Remaining-949 ft 3 Class C* Shipped to date -none* Remaining

-424 ft 3 GTCC -The estimated volume of Greater than Class C (GTCC) waste, resulting from the dismantlement of the reactor internals, is approximately 48.4 cubic feet. Current plans call for the amendment of the ISFSI 10 CFR Part 72 license to accommodate the storage of the GTCC material within the ISFSI until its final disposition, anticipated to be in the Spent Fuel Repository.

Revision 1 RSNGS Historical Site Assessment 45 August 2006 6.8.3 Spent Fuel The spent fuel transfer to the ISFSI was completed in August 2002. Spent fuel will remain in the ISFSI until the Federal Spent Fuel Repository becomes operational, sometime after 2010 based on current estimates attained from the Department of Energy's Yucca Mountain Project website.6.9 Incident Descriptions Based on the review of existing plant records (annual and semi-annual reports, licensee notifications, Occurrence description reports, and PDQ's) approximately 260 incidents with radiological or hazardous material implications occurred between commencement of plant operation in 1974 and approval to continue decommissioning through license termination in 1999. A number of these took place within the power block and, while contributing to the radiological contamination of the power block structures, were generally contained within the RCA. Those occurring outside of the power block have contributed to the Impacted classification of substantial portions of the Industrial Area. These include: " Airborne releases with structural or geological contamination potential;

Spills outside of the power block or incidents involving potential contamination based on system leakage from systems that had been historically contaminated by primary to secondary leaks;" Loss of control of radioactive materials resulting in the potential for contamination outside of the power block;* Plant liquid radioactive effluents resulting in soil contamination;" Hazardous material spills or losses of control; and" Contamination of systems not originally designed as radioactive systems outside of the historic power block.A summary index of these incidents is included as Appendix A.6.9.1 Radiological Spills The records search showed that between 1974 and 1999, 158 documented spills occurred at the facility.

Less than forty of tliese documented spills occurred within the power block and, while contributing to the radiological contamination of the power block structures, were generally contained within the radiologically controlled drains and waste systems. These spills and releases can be grouped into three basic categories as described below." Spills that were ultimately contained within the site's controlled process drain system (including the oily water separator, RHUT's, and retention basins), contaminating the surfaces between the spill site and drain;* Spills ultimately entering the site's uncontrolled storm drain system contaminating the drain system as well as the surfaces between the spill site, the drain and the outfall; and Revision 1 RSNGS Historical Site Assessment 46 August 2006

Spills resulting in the saturation and contamination of the media in the immediate area surrounding the. spill (i.e., concrete, soil, asphalt, gravel, etc.).These spills generally resulted in the affected areas being designated as Impacted Areas for FSS design purposes.6.9.2 Chemical Spills The records search revealed that between 1974 and 1999, twenty-eight documented cases involving the mishandling or loss of control over hazardous chemical materials exist. These range from spills of acids and caustics used in the plant's various systems to anti-freeze and transmission fluid from District vehicles.

There were a minimal number of chemical spills occurring outside of the building comprising the historic power block. A majority of these occurred within one of the facility's structures.

These spills were controlled and remediated in accordance with the policies and procedures associated with these occurrences, including:

Ranch Seco Hazardous Materials.

Business Plan;* RSAP -0229, Hazardous Waste Management;

RSAP'- 0223, Oil Spill Prevention, Control,'and Countermeasuresl

OP-C-32, Onsite Oil Spill;* OP-C-46A, Hazardous Material Spill/Release; and* Rancho Seco Emergency Plan.6.9.3 Loss of Material Control The records search showed that between 1974 and 1998, there are 12 documented cases regarding the loss of control of radioactive material or material contaminated with radioactive material resulting in the potential for contamination spread in the immediate vicinity.

Areas affected by these incidents will be initially classified as Impacted Areas.6.9.4 System Cross-Contamination Starting in 1975, with indications of crpss contamination of the CCW system from the RCS and expanding dramatically in 1981 with the first indications of primary to secondary leakage through the OTSGs, systems not originally expected to contain radioactivity became contaminated.

The level of contamination varied from system to system and in general, was minimal.In accordance with plant chemistry and surveillance procedures, open cycle and closed cycle cooling systems, auxiliary systems, tankage, and standing water were routinely monitored.

In accordance with the guidance of NRC IE Notice 80-10, non-contaminated systems were routinely monitored for radioactivity, and those systems with measurable activity were evaluated (typically through an Engineering or 10 CFR Part 50.59 review process) for potential impacts against the 10 CFR Part 501 Appendix I criteria.Revision 1 RSNGS Historical Site Assessment 47 August 2006 The potential exists for leaks from these systems to have resulted in the contamination of additional site systems and locations not originally expected to be contaminated.

Based on the records search performed for the HSA investigation, 165 documented cases involving events of this nature occurred during the operation of RSNGS. These areas, primarily within the Turbine Building and Tank Farm, are classified as Impacted Areas.6.9.5 Onsite Disposal of Licensed Radioactive Materials The records search and personnel interviews did not reveal any indication of onsite disposal of licensed radioactive materials.

Also, a database search of communications with the AEC/NRC did not reveal any requests for approval of proposed alternate disposal procedures under the provisions of 10 CFR 20.302 or 10 CFR 20.2002. Therefore, the District concludes that onsite disposal of radioactive materials has not occurred at this site.6.10 Survey Unit Identification and Classification 6.10.1 Site Classification The identification, designation, and classification of individual survey units are an ongoing process that will be completed prior to submittal of the Final Status Survey Plan contained within the License Termination Plan.6.10.2 Assessment Performance The Site Characterization working group of the Decommissioning Planning Team will perform the assessments required to assign preliminary Area and Survey Unit classifications, and Survey Unit identification codes to the site.6.10.3 Areas The entire 2,480 acre site is divided into Areas. Areas are typically larger physical sections of the site that may contain one or more survey units depending on their classification.

Areas that have no reasonable potential for residual contamination are classified as Non-Impacted Areas. These Areas have no radiological impact from site operations and are typically identified early in decommissioning.

Areas with reasonable potential for residual contamination are classified as Impacted.

Impacted Areas of the site are depicted in Figure 6.1, Impacted Area Designations.

Areas of the 2,480 acre site not depicted in Figure 6.1 as Impacted are classified as Non-Impacted.

6.10.4 Survey Units A Survey Unit is a physical area consisting of buildings, structures, or land areas of specifically defined shapes and sizes, for which a unique decision will be made regarding if the presence of any residual radioactive material meets or exceeds predetermined release criteria.

A Survey Unit is a single contiguous area, whose size is dependent upon its physical characteristics (open land vs. structural building, dry hillside vs.:wetland marsh), radiological conditions (Impacted vs. Non-Impacted, remote material storage area vs. a CSCA), and whose operational conditions are reasonably consistent with the exposure modeling used to Revision 1 RSNGS Historical Site Assessment 48 August 2006 determine the classification. (A Survey Unit will carry.a single classification as described in table 6.3. An area whose physical or radiological conditions mandate multiple classifications will be divided such that each Survey Unit will have a single, consistent classification.)

6.10.5 Initial Designation of Areas Using reasonable and available physical and documented references, nine Areas were identified and assigned Area identification numbers. Except as noted below, Areas one (100000) through seven (700000) are located outside of the Industrial Area while Area eight (800000) is comprised of the entire Industrial Area. Area nine (90000Q) contains all portions of the 2,480 acre site not included in Areas one through eight.Current Area designations (coordinates as referenced on SK-RP-0001, Radiological Characterization Plot Map) are: " Area 100000, Plant Effluent Water Course bounded by AA2, AA16, AF16, AI18 and AY2 (back to AA2);* Area 200000. South Plant Outfall bounded by Al19, A139, A039, and A013.(back to AI19);" Area 300000, Southern region bounded by AY2, AP13, AP39, and AZ39 (back to.AY2);* Area 400000, South Eastern region bounded by Y40, Y66, AY66, and AY40 (back to Y40);" Area 500000, North Eastern region bounded by AE37, T37, U35, V35, V38, X38, X66, and AE66 (back to AE37) -Note: Area 5 contains two Impacted Survey Units; one that is bounded by Q40, R40, R37, U37, U35, V35, V38, X38, X44, and Q44 (back to Q40) plus one consisting of those cells through which the access roadto highway 104 passes;" Area 600000, Northern region bounded by AE2, L2, L36, and AE36 (back to AE2);" Area 700000, Western region (excluding ISFSI and that portion transversed by the railroad spur) bounded by M2, M20, N20, Q19, U19, W16, Z16, and Z2 (back to M2);" Area 800000 -Those portions of the District-controlled Rancho Seco property not included in and surrounded by SA01-SA07.

Area 800000 (SA08) is also commonly referred to as the Industrial Area and lies primarily within the industrial area fence with the notable exception of parking areas located to the east of the site. (bounded by M21, N21, P19, U19, X17, AF17, AH19, AH39, Y39, Y37, W37, W34, T34, T36, and M36 (back to M21)),_and" Area 900000 -Those portions of the District-controlled Rancho Seco property not included in Areas 100000 through 800000.Areas of the site are depicted in Figure 6.2, Area Designations.

Revision 1 RSNGS Historical Site Assessment 49 August 2006 6.10.6 Survey Unit Designation Program The Impacted Areas are being further subdivided into survey units and assigned a unique Survey Unit Identification Number (SUID) along with a preliminary classification.

Descriptions of the initial Survey Units identified are provided in Appendix C. These initial Survey Units may be either further divided or combined and will be classified during design of the FSS.The guidance provided by the MARSSIM Classification matrix is provided in Table 6.3 below.Revision 1 RSNGS Historical Site Assessment 50 August 2006 S SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT DWG: 000002 Impacted Areas Figure 6.1 Impacted Area Designations Revision 1 51 August 2006 RSNGS Historical Site Assessment Figure 6.2 Area Designations Revision 1 52 August 2006 RSNGS Historical Site Assessment TABLE 6.3 MARSSIM Survey Unit Classification Matrix Area Survey requirements Area Definition Structures Land Scan Sampling / direct EMC evaluation Instrument Classification measurement MDC Areas, as determined during Nn thHShaving no reasonableN/

Non- the H No limit No limit None required None required Not required N/A Impacted potential for residual radioactive contamination.

Impacted areas not expected to Impacted contain residual contamination No limit No limit Judgmental Random Required 0.1 DCGLw Max Class III above fraction of DCGLw[10%]Impacted Impacted areas not expected to 1,000 mn 2 10,000 mn 2 10-100% Systematic Required 0.5 DCGLw Max Class II exceed DCGLw Impacted areas with potential to exceed DCGLw, isolated Impacted areas to exceed DCGLEmc, or 100 m 2 2,000 m 2 100% Systematic Required 0.5 DCGLw Max Class I where remediation has been performed to meet DCGL criteria Revision 1 Anqt 7200l6 R'.RW('rq Rktorinal Site. kqqeq-,ment 51 6.11 Radiological Impact Summaries 6.11.1 Area 100000 (SAO1) -Plant Effluent Area Available documentation of the radiological impacts associated with the evaluations from specific incidents during the operational and post operational period include: 6.11.1.1 Licensee identified events Document Equipment/System/location Remarks ODR 75-46 RHUT overflow -1,765 gal overflowed to PE before divert (H1-3 only)ODR 76-79 PE diversion for road construction Flow rate calculation re-altered PE flow measurements verified with minimal impact noted.ODR 81-192 RHUT sample line discharges Cumulative impact unknown directly to PE (> 500 g+/-Ci Co-60)[Also ODR81-193, 209]ODR 84-223 CST (T-358) overflow -900 Release within 10 CFR Part gallons 20 limits 96 ILCi H-3,.__ _ _0.21 [tCiCs-137toPE ODR 87-764 System drained in contaminated Cs-137 at 1.75E-7 gtCi/ml area removed without sample 55 (no mention of any diversion gal. Dumped down uncontrolled of PE) 1987 semi-annual storm drain between Aux and RB report -1000 gal. Max dose 3.33E-4 mrem.1988 annual report Cs-137 detected during routine 57 IiCi Cs-137 in 3.10 E+06 monitoring gal. release -Est. dose 0.0.125 mrem 1988 annual report MSR valve leakage between April Turbine Building floor drains and September to PE --88 gal./- 3 ItCi H-3, Cs-I34, and Cs-137 released.PDQ 89-512 Radiological survey results (up to No limits were exceeded 58 uR/hr contact) alcng creek raise (activity resulted from concerns associated with EPA permitted releases)criteria Revision 1 August 2006 RSNGS Historical Site Assessment 54 6.11.1.2 Independent Evaluations Conducted Document Equipment/System/location Remarks UCID-20267 Rancho Seco Liquid Effluent Study to establish and define the Pathway Aquatic and potential exposure pathways Terrestrial Dietary Survey associated with the liquid Report -November 30, 1984. effluent releases from RSNGS.UCID-20295 Concentration of Established basic correlations Radionuclides in Fresh Water* between species, diet, size, and Fish Downstream of Rancho radiological concentration of Seco Nuclear Generating Plant common game fish in-December 27, 1984. downstream waterways.

Using consumption data from UCID-20267, calculated maximum intakes of Cs-137 in the 70,000-pCi/year range.UCID-20298 Radionuclides in Sediments Estimated that only 20% of the Collected Downstream from Cs-134/137 discharged between Rancho Seco Nuclear Power 1981 and 1984 are associated Generating Station'.

with the bottom sediments (to a depth of 12 cm.) in Clay, Hadselville, and Laguna Creeks to a distance of 16.2 miles (26___Ian) from the plant UC-ID-20367 Environmental Radiological Primarily summarizes UCID -Studies Downstream from 20267, 20295, & 20298 and Rancho Seco Nuclear Power recommends further Generating Station. March 22, investigation of aquatic and 1985 terrestrial food source pathways UCID-20641 Environmental Radiological Part I documents follow-up Studies Downstream from the investigation of radioactivity Rancho Seco Nuclear Power. concentrations in fish and Generating Station -1985. sediment samples. Part II February 6, 1986. contains appendices with I sample data RSN(jS Historical Site Assessment Revision 1 August 2006 55 Independent Evaluations Conducted (Continued)

Document Equipment/System/location Remarks NUREG/CR-4286 Evaluation of Radioactive Based on the analysis of the data (ORNL-6183)

Liquid Effluent Releases From gathered, the potential for the Rancho Seco Nuclear exposures above 25 mrem/yr Power Plant. March 1986. appear highly unlikely, stating that in its summary "... it seems reasonable to assume that unless some individual is eating 14 to 18 kg of fish per year caught in the sump, Clay Creek, or Hadselville Creek at Clay Station Road, a 25 mrem/year dose ... is not reached by any individual around Rancho Seco." UCID -20963 Environmental Radiological Documents the continuation of Studies Conducted During the environmental monitoring 1986 in the Vicinity of the research being performed.

Cs Rancho Seco Nuclear .Power concentration in fish has Generating Station. March 22, returned to background at 1987 distances greater than 7.5 km from the plant effluent boundary.UCRL-106111 Environmental Radiological Documents the 1989 follow-up Studies in 1989 Near the to the environmental effluents Rancho Seco Nuclear Power studies performed in 84-87.Generating Station. November Recommendations include 1990. suspension of the studies unless a normal or above normal precipitation cycle prompts an evaluation of the potential redistribution of the activity inventory.

None Rancho Seco Non- Determined that there Industrial Area is now "no presence of Survey Project. contamination Shonka Research discemable from Associates, Inc. June background" with the 2001. exception of the effluent path itself and the swales associated with it.Revision 1 August 2006 RSNGS Historical Site Assessment 56 6.11.1.3 District Initiated Evaluations

.-Document Equipment/System/location Remarks -RPDP 90-001 Over reporting of effluent Based on residual activity release activities for Agl 1Om, detected in retention basin Co-57, .Co-58, Co-60, Cs-134, sludge during clean up activities Cs-137, Mn-54, & Sb-125 by in 1985 & 1989. Ag-110m-30%, up to 40% Co-57-2%, Co-58<1%, Co-60--26%, Cs-134-2%, Cs-137-3%, Mn-54--2.5%, & Sb-125-42%RPDP 90-010 A multiple topical study, Estimate that -350 ftW of including "Field #14" Soil dredging wastes will fail to contamination, decay to less than the anticipated 10 mreno/standard utilized in 1990. (See 91-006 for follow-up)

RPDP 91-006 Radiological characterization Summarized investigation Along the Plant Effluent documentation between 1985 Stream. and 1989 in preparation for further studies. Noted the elevated levels detected in the dredge piles and that -1020 ft 3 of these piles had been_ _containerized as radwaste.RPDP 92-004 Effluent course Soil contamination depth profile I characterization Revision 1 August 2006 RSNGS Historical Site Assessment 57 District Initiated Evaluations (Continued)

Document Equipment/System/location Remarks RPDP 92-005 Offsite Soil Sector survey Provided characterization data from within an approximate 2000-foot radius of Reactor Containment Building (3600)surrounding facility with direct measurement and Soil sample correlations.

RPDP 92-006 Effluent wastewater course Provides a summary of studies radiological characterization to date and established soil contamination half-lives and remediation options.RPDP 92-008 Soil activity vs. Measured Early attempt to correlate the exposure rate wastewater course soil activity to direct gamma area. readings.RPDP 92-009 Half-life Calculations for Clay Estimates environmental half-Creek Bank life of effluent creek at -4 years RPDP 92-010 TEDE calculation for soil 186 mrem/year, decaying to sample taken at grid location Al- 9.9 mrem/year in -4 half-lives 16 (17 years).RPDP 93-002A Evaluation of Soil in Area AH & Additional data attempting to Al-15 correlate soil activity and direct dose measurements RPDP 93-003 Evaluation of Soil in Area AM-5 Additional data attempting to correlate soil activity -direct dose measurements and various depth of soil removal.RPDP 93-006 Evaluation of Soil in Area AN-2 Activity concentration vs.depth to 6" RPDP 93-008 Offsite Soil Sector Survey Provided characterization data within 3-mile radius, 3600 surrounding facility with direct measurement and soil sample correlations.

Revision 1 August 2006 RSNGS Historical Site Assessment 58 District Initiated EvaluAtion's (Continued)

Document Equipment/System/location Remarks RPDP 94-003 Soil environmental half-life Estimates environmental evaluation, half-life of effluent creek at_____ _____ ____4 years RPDP 95-004 Radiological Characterization Summarizes the Report characterization effort and the decision not to remediate the effluent canal.RPDP 95-007 Offsite uR/hr versus Soil Activity Provides two different Correlation models with which to estimate annual exposure from measured dose rates in_ _the effluent canal area.Revision 1 August 2006 RSNGS Historical Site Assessment 59 6.11.2 Area 200000 (SA02) -South Plant Outfall Area Available documentation of the radiological impacts associated with the evaluations from specific incidents during the operational and post operational period include: I 6.11.2.1 Licensee Identified Events Document Equipment/System/location Remarks ODR 82-0248 Leakage from (auxiliary)

Plant Effluent large boiler ran down storm H-3 4.5E-06 to 6.6E-06 drain (p.Ci/ml)ODR 84-0217 Hydro-pump hose burst -Hydro source CST -H-3 water down storm drain 2.OOE-05 gtCi/ml ODR 84-0317 Drain hose fails releasing 500 2.20E-05 gCi/ml -2880 gallons from T-993 to storm gCi total release drain ODR 85-0075 Hole in "B" RHUT releases -2.OOE-04 jiCi/ml at storm 1000 gallon to storm drain drain -< 4.30E-06 at the outfall PDQ 90-0367 H-3 Evap (RWS-730) leaks H-3 at 3.8E-02 and Cs-500 gallons across Tank Farm 137 at 3.6E-08 [iCi/ml into storm drain south of East cooling tower PDQ 93-0088 A RHUT agitator leaks 450 Release -gallons down storm drain. 37 p.Ci H-3, 8.30E-03 gCi Co-60, 3.15E-03 J.Ci Cs-134, 8.52E-02 aCi Cs-137 PDQ 02-0015 B RHUT agitator leaks 450 H-3 at 4.42E-06 and Cs-gallons down storm drain 137 at 2.80E-09 p.Ci/ml resulting in an unmonitored release 6.11.3 Areas 300000-700000 With the exception of two Impacted Survey Units contained in Area 500000 as described in Section 6.10.5, no radiological impacts were identified that impacted these Areas.One Impacted Survey Unit within Area 500000 consists of the employee parking lot, Parking Area #2 and Parking Area #4. One event was identified in this area, ODR 870301 where a pallet with articles tagged "Contact RP prior to disassembly outside RCA" was found in this area. Also, this area has been used as a staging area for radioactive material shipments, both incoming and outgoing.Revision 1 RSNGS Historical Site Assessment 60 August 2006 The second Impacted Survey Unit consists of those cells through which the access road to highway 104 passes. Since this access road serves as& te-point of egress and ingress of radioactive material shipments, it must be classified as Impacted in accordance with MARSSIM classification guidance.6.11.4 Area 800000 (SA08)Area 800000 is comprised of that area of the site known as the Industrial Area. The identified radiological impacts on the Industrial Area are too numerous to summarize here. A brief summary of each radiological occurrence is included in Appendix A, HSA 10 CFR Part 50.75(g) Document Review Summary.6.11.5 Area 900000 (SA09)Area 900000 is comprised of those areas of the entire 2,480 acre site not contained in Areas 100000 through 800000.Revision 1 RSNGS Historical Site Assessment 61 August 2006 This page intentionally left blank Revision 1 August 2006 RSNGS Historical Site Assessment 62 7.0 FINDINGS RSNGS, like all commercial nuclear power plants, is designed with multiple boundaries to contain the unit's radioactive contents within its many systems, components, and structures.

Many of these systems and structures have been impacted due to routine operations and maintenance activities during the operational and post operational history of the plant.Structures anticipated to be classified as Impacted by the unit's operation include the Reactor Containment Building, Auxiliary Building, Spent Fuel Storage Building, Interim Onsite (radwaste)

Storage Building (IOSB), and much of the Tank Farm and the systems contained within it. Other systems, components and structures that were not originally anticipated to be contaminated have been impacted as the result of system cross contamination between the primary coolant system and secondary steam systems due to the failure of tubes within the unit's OTSGs. Areas and systems impacted as a result of these primary to secondary leaks include: " Turbine Building;* Emergency Feed pumps;" CST in the tank farm;" Regenerate Holdup Tanks;" Auxiliary Boilers;" Main and Auxiliary Steam Systems;" Main Feed Water System;." Retention basins;" Condensate System; and" Auxiliary Feed Water System.Other major non-nuclear systems became contaminated by leakage directly from the primary system or by materials that had been in contact with primary coolant including

[" Nitrogen Gas System;* Control Rod Drive Cooling System;" Service Air System;* Nuclear Service Cooling Water System; and* Turbine/Component Cooling Water System.System leakage from these systems in turn Contaminated the Clean Drain System.As referenced earlier in the report, Area 8000QQ00 comprising the Industrial Area, as well as Areas 100000 and 200000 and the Impacted portion of Area 500000 will be divided into unique survey units consistent with the guidance contained in MARSSIM. The initial MARSSIM classification of these areas will be based on the design function of the area of Revision 1 RSNGS Historical Site Assessment 63 August 2006 concern (AOC) or its operational history. Of particular significance are those areas historically referred to as the power block. These include:* Reactor Containment Structure;

Auxiliary Building;* Spent Fuel Building;* Turbine Building; and* Tank Farm.In general, these areas are being assigned Impacted Area classifications.

Should information be developed during the course of the project supporting reclassification of these areas, the circumstances and rationale will be documented appropriately.

During the operational history of the facility, radioactive liquid spills, radioactive waste processing, storage, and certain maintenance activities on contaminated equipment and components occurred outside of the historic power block. These occurrences have resulted in the preliminary assignment of Impacted Area classifications to the areas affected.

These include, in part:* North and South Turbine Building lay down areas;* Radioactive Waste Barrel Farm;* Radioactive Waste Solidification Pad (East of Auxiliary Building grade);* Machine Shop;* Auxiliary Building yard area;* Construction and Pipe Fabrication Shops; and* "C" warehouse.

Should future survey data support reclassification of these areas, the circumstances and rationale will be documented appropriately.

Several occurrences involving radioactive materials have potentially impacted other areas outside the RCA. These include the storage of radioactive materials in the following locations: " Turbine Rotor Storage Shed;" Paved access surrounding the East and West Spray Ponds;" Quonset Hut;" Switchyard;" Main site tool room; and" North and South Storage Yards.Revision 1 RSNGS Historical Site Assessment 64 August 2006 Incident specific survey and post remediation survey results have been used in the assignment of a preliminary Survey Unit classification' of Impacted.The District-controlled property outside of the Industrial Area has been initially classified as Non-Impacted with the exception of the storm drain outfalls (Area 200000) and the plant effluent water course way (Area 100000).These preliminary classification assignments have been substantiated by the Non-Industrial Area survey work performed by Shonka Research Associates, Inc. This project provided direct scanning of over 300,000 square meters accompanied by over 80,000 gamma spectral samples without the detection of any radioactive material of site origin above background.

Table 7.1 Area Designations Area 100000 (SAO1) Impacted Area 200000 (SA02). Impacted Area 300000 (SA03); Non-Impacted Area 400000 (SA04) Non-Impacted Area 500000 (SA05) , NonImpacte'd*

Area 600000 (SA06) Non-Impacted Area 700000 (SA07) .Non-Impacted Area 800000 (SA08) Impacted Area 900000 (SA09) Non-Impacted

Area 500000 contains an impacted area within it as described in Section 6.10.5.I RSNGS Historical Site Assessment Revision 1 August 2006'65 This page intentionally left blank RSNGS Historical Site Assessment 66 Revision 1 August 2006

8.0 CONCLUSION

S The RSNGS HSA provides sufficient evidence to support Impacted Area classification for Area 100000, Area 200000, and Area 800000 only. Area's 300000 through 700000 and 900000 shall be classified as Non-Impacted Areas and excluded from further investigation and survey actions with the exception of two Impacted Areas within Area 500000 as described in Section 6.10.5.Based on current and historic sample results from the licensees Radiological Environmental Monitoring Program (REMP), there is no indication that surface waters on or near the facility'or the ground water off of the site has been affected by the licensed operation of the facility.However, further evaluations of the groundwater directly below the licensed facility are also planned prior to the LTP submittal.

The plant effluent watercourse contains deposits with measurable amounts of radioactive material resulting from liquid releases conducted in accordance with the regulatory and permit requirements imposed on the facility.There were periods of liquid effluent releases during operation of the plant where it was determined that calculated dose to a maximally exposed individual via the liquid effluent pathway exceeded the design objective level of 10 CFR Part 50, Appendix I. However, it was also determined that these liquid effluent releases did not exceed the concentration limits of 10 CFR Part 20 or the fuel cycle dose limit of 40 CFR Part 190. The need for remediation of this material, the dose from which has already been accounted for in accordance with the regulation governing radioactive effluent from power plants will be determined prior to submittal of the LTP.RSNGS Historical Site Assessment 67 Revision 1 August 2006 This page intentionally left blank Revision 1 August 2006 RSNGS Historical Site Assessment 68

9.0 REFERENCES

9.1 NUREG-1575

-Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM)9.2 Radiological Characterization Plan for the Rancho Seco Nuclear Power Generating Station (RCPRSNPGS including Quick Look (April 4 and 14, 1990), Phase I (April 14 through May 9, 1990), and Phase I (1991 through 1997)9.3 NUREG/CR-2082

-"Monitoring for Compliance with Decommissioning Termination Survey Criteria" 9.4 NRC draft Regulatory Guide DG-1005 "Standard Format and Content for Decommissioning Plans for Nuclear Reactors 9.5 Sacramento Municipal Utility District, Rancho Seco Nuclear Generating Station, Unit No. 1, Final Safety Analysis Report 9.6 Sacramento Municipal Utility District, Rancho Seco Nuclear Generating Station, Unit No. 1, Updated Final Safety Analysis Report 9.7 Sacramento Municipal Utility District, Rancho Seco Facility, Defueled Safety Analysis Report 9.8 Safety Evaluation by the Directorate of Licensing, US Atomic Energy Commission, in the matter of Sacramento Municipal Utility District, Rancho Seco Nuclear Generating Station, Unit 1, Docket 50-312 9.9 Rancho Seco Nuclear Generating Station Proposed Decommissioning Plan" (PDP)9.10 Plan for Ultimate Disposition of the Facility" (PUDF), July 1990 9.11 Final Generic Environmental Impact Statement on Decommissioning of Nuclear Facilities, NUREG-0586, August 1988 (GEIS)9.12 Geotechnical Investigation for Proposed Evaporation Ponds, ERPT-C0104, Rev.1, 1989 9.13 Final Engineering Report Assessment of Spent Fuel Liner Leakage, ERPT-M022 1, Rev.0, 1990 9.14 Response to NRC questions on Geologic and Seismologic Conditions 1987 9.15 NUREG/CR-4286, Evaluation of Radioactive Liquid Effluent Releases From the Rancho Seco Nuclear Power Plant, March 1986 9.16 Annual Radiological Environmental Operating Report, January -December 2002, Rancho Seco Nuclear Station, Herald, California 9.17 Rancho Seco Non-Industrial Area Survey Project Rev. 2 -Shonka Research Associates, Inc June 26, 2001.Appendices and Addendums Revision 1 RSNGS Historical Site Assessment 69 August 2006 9.18 Federal Register, Vol. 64, No. 234, December 7, 1999, FR Doc. 99-31508 9.19 Rancho Seco Independent Spent Fuel Storage Installation Final Safety Analysis Report Volumes I, II, and III 9.20 Bechtel Corporation, Construction Report for Rancho Seco Nuclear Generating Station Unit No. 1, January 15, 1976 9.21 Report 204 1-RE-009, Rev. 1, Rancho Seco Activation Analysis and Component Characterization, WMG, Inc., July 2003 9.22 PNL (Pacific Northwest Laboratory), 1984 "Residual Radionuclide Distribution and Inventory at Rancho Seco Nuclear Generating Station." PNL-5146, June 1984 Revision 1 RSNGS Historical Site Assessment 70 August 2006 10.0 APPENDICES AND"ADDENDUMS Appendix A: HSA 10 CFR Part 50.75(g) Document Review Summary Appendix B: Personnel Interview Program Appendix C: Area Summary and Preliminary Survey Unit Identification Appendix D: Miscellaneous Location and Earthquake Data and Figures Appendix E: Miscellaneous Historical Construction Photographs RSNGS Historical Site Assessment Revision 1 August 2006 71 This page intentionally left blank Revision 1 August 2006 RSNGS Historical Site Assessment 72

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SUMMARY

1.0 INTRODUCTION

References:

8.0 CONCLUSION

9.0 REFERENCES

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