ML20210K898

Draft Environmental Statement for Decommissioning Humboldt Bay Power Plant,Unit 3.Docket No. 50-133.(Pacific Gas and Electric Company)

ML20210K898
Person / Time
Site:	Humboldt Bay
Issue date:	04/30/1986
From:	Office of Nuclear Reactor Regulation
To:
References
NUREG-1166, NUDOCS 8604290114
Download: ML20210K898 (54)

Text

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NUREG-1166 Draft Environmental Statement for decommissioning Humboldt Bay Power Plant,  !

Unit No. 3

< Docket No. 50-133 Pacific Gas and Electric Company

U.S. Nuclear Regulatory Commission Offico of Nuclear Reactor Regulation l

April 1986 y e ncoq l

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NOTICE Availability of Reference Materials Cited in NRC Publications Most documents cited in NRC publications will be available from one of the following sources:

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NUREG-1166 Draft Environmental Statement for decommissioning Humboldt Bay Power Plant, Unit No. 3 Docket No. 50-133 Pacific Gas and Electric Company U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation April 1986 h

ABSTRACT This Draft Environmental Statement (DES) contains the assessment of the envi-ronmental impact associated with decommissioning the Humboldt Bay Power Plant Unit 3 located 4 miles southwest of the city of Eureka, Humboldt County, Cali-fornia. This DES is prepared pursuant to the National Environmental Policy Act of 1969 (NEPA) and Title 10 of the Code of Federal Regulations, Part 51, as amended, of the Nuclear Regulatory Commission regulations. The proposed decom-missioning would involve safe storage of the facility for about 30 years, after which the residual radioactivity would be removed so that the facility would be at levels of radioactivity acceptable for release of the facility to unre-stricted access, i

This DES has been prepared by the NRC Office of Nuclear Reactor Regulation. No i assistance from other Federal agencies was obtained in its preparation. Addi-tional information on this DES and on the Decommissioning of Humboldt Bay Unit 3 can be obtained from Peter B. Erickson, Project Manager, Standardization and Special Projects Directorate, U.S. Nuclear Regulatory Commission, Washington, D.C.

20555. Mr. Erickson can be reached on (301) 492-8194.

l Humboldt Bay Unit 3 DES iii

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SUMMARY

-AND CONCLUSIONS This Draft Environmental Statement (DES) was prepared by the U.S. Nuclear

Regulatory Commission, Office of Nuclear Reactor Regulation (hereinafter ,

( referred to as the staff).

~

(1) This action is administrative. -

! (2) The proposed action is to approve plans.by Pacific Gas and Electric

1. Company (the licensee) .to decomission the Humboldt Bay Power Plant, i Unit 3. The proposed decomissioning would involve safe storage of

. the facility for about 30 years, after which the residual-

[ radioactivity would be. removed so that the facility would be at levels of radioactivity acceptable for its release to unrestricted access. The

.' spent fuel would remain on site in the spent fuel storage-pool until a Federal repository is available to receive it.

(3) Humboldt Bay Unit 3, a 65 MW electric boiling water reactor, operated i

'comercially from August 1963 until July 1976, at which time it was' shut j down for seismic modifications. In 1983, the licensee concluded that the

seismic requirements and the requirements imposed on reactor licensees

as a result of the accident at Three Mile Island, Unit 2 made continued -

operation too costly to consider and, therefore, decided to decommission the plant.

j (4) This DES assesses the various impacts associated with the SAFSTOR r option for decomissioning, as proposed by the licensee. It also

! assesses other decomissioning options as discussed in Section 1.3.

1 4

The information in this DES is an assessment of the environmental impact of decomissioning Humboldt Bay Unit 3. pursuant to guidelines of the National Environmental Policy Act of-1969 (NEPA) and 10 CFR Part 51 of the Ccmmission's Regulations.

, (5) The staff has reviewed the potential impacts,- both beneficial and 1 adverse, of tha proposed decomissioning plan. The staff's j conclusions an sumarized as follows:

l (a) Storing the spent fuel assemblies-at Humboldt Bay is the sole

viable alternative for" spent fuel storage at this time. 10 CFR 4

Part 51.23(a) states that the Commission has made a generic determination that for at least 30 years beyond the. expiration of

! reactor operating licenses, no significant environmental impacts..

I will result from th storage of spent fuel in reactor facility

. storage pools.

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(b) The lic'ensee has established a radiation protection program that

. ' will maintain radiation exposures within the applicable-limits of 10 CFR Part 20 and will maintain exposures ALARA in accordance with NUREG-0800 and Regulatory Guide 8.8.

3 i

Humboldt Bay _ Unit 3 DES y i

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(c) A fuel handling accident would result.in atmospheric radionuclide releases that are well below EPA Protective Action Guide (PAG) levels.

(d) Damage to all the stored fuel assemblies resulting from a non-mechanistic heavy load drop would result in atmospheric radionuclide-releases that also are well below the PAG levels.

(e) There is a negligibly small-likelihood that seismic loads or other mechanical loads would generate criticality among the spent fuel assemblies stored in the pool.

(f) The upper . limits of potential lung, . liver, and bone doses resulting from an instantaneous expulsion to the atmosphere of the entire water /radionuclide content of the spent fuel pool are very small fractions of the PAG levels.

(g)- A rupture of the spent fuel pool or the liquid radwaste tanks would result in a total body dose to-an average individual via the-seafood chain that would be less than the dose from natural background levels.

Doses resulting from water recreational activities in Humboldt Bay would be negligible.

(h) As a result of its analysis and review of potential environmental, technical, and societal impacts, the staff has determined that Humboldt Bay Unit 3 can be placed in SAFSTOR for a 30-year period with minimal environmental impact.

(6) This DES is being made available to the public, to .the Environmental Protection Agency and to other Federal, State and local agencies as specified in Section 8.

(7) The personnel who participated in the preparation of this DES and their areas of responsibility are identified in Section 7.

(8) On the basis of the analyses and evaluation's set forth in this DES, it is concluded that the action called for under NEPA and 10 CFR Part 51 is the-issuance of an amendment to authorize Humboldt Bay _ Unit 3 to be decounissioned in the SAFSTOR mode as proposed by the licensee.-

Humboldt Bay Unit 3 DES vi ax- -

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TABLE OF CONTENTS gPa e ABSTRACT........................................................ 111

SUMMARY

AND CONCLUSIONS......................................... v 1 INTRODUCTION.................................................. 1-1 1.1 Background............................................... 1-1 1.2 Proposed Action.......................................... 1-2 1.3 Decommissioning Alternatives............................. 1-2 1.3.1 DEC0N............................................. 1-2 1.3.2 ENT0MB............................................ 1-2 1.3.3 SAFST0R........................................... 1-3 1.3.4 No Action......................................... 1-5 2 DESCRIPTION OF PLANT AND PROPOSED DECOMMISSIONING PLAN........ 2-1 2.1 Humbol dt Bay Power Plant Uni t 3. . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Decommissioning Plan..................................... 2-5 ]

3 ENVIRONMENTAL IMPACTS......................................... 3-1 )

3.1 Assessment of Nonradiological Impacts of Decommissioning 3-1 3.1.1 Socioeconomic and Cultural Resources.............. 3-1 3.1.2 Hydrology......................................... 3-l' 3.1.3 Aquatic Resources................................. 3-1 3.1.4 Terrestrial Resources............................. 3-2' 3.1.5 Endangered and Threatened Species................. 3-2 l 3.1.6 Land Use.......................................... 3-2 3.1.7 Water.Use......................................... 3-3 3.1.8 Unavoidable Environmenta1' Impacts................. 3-3 3.1.9 Local Short-Term Uses versus Long-Term Productivity...................................... 3-3 ,

3.1.10 Irreversible and Irretrievable Commitments of=  !

Resources......................................... 3-3 3.2 Assessment of Radiological Impacts of Decommissioning.... 3-3 l 3.2.1 Occupational Radiation Exposure................... 3-4  ;

3.2.2 Radioactive Waste Management Systems.............. 3-6 l l 3.2.3 Postulated Accidents.............................. 3-7 3.2.3.1 Evaluation............................... 3'-9 3.2.3.2 Fuel Handling Accident................... 3-9 3.2.3.3 Fuel Assembly Damage Cause'd by Non-Mechanistic Heavy Load Drop or Si te-Rel ated Haza rds . . . . . . . . . . . . . . . . . . . . . 3-9 Humboldt Bay Unit 3 DES vii

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TABLE OF CONTENTS (Continued) l Page j 3.2.3.4 Criticality Potential of Stored Spent Fuel Rearranged as a Result of Sei'smic or Other Mechanical Loads. . . . . . . . . . . . . . . . 3-10 3.2.3.5 Non-Mechanistic Expulsion of. Pool Water and Radionuclide Contaminants to the A tmo s phe re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11 3.2.3.6 Spent Fuel Pool Rupture.................. 3-12 3.2.3.7 Uncontrolled Release of Radwaste Tank l

Contents................................. 3-12 4

SUMMARY

OF DECOMMISSIONING ALTERNATIVES....................... 4-1 5-I 5 CONCLUSIONS...................................................

6 REFERENCES....................................................

6-1 7 CONTRIBUTORS..................................................

7-1 8 LIST OF AGENCIES AND ORGANIZATIONS TO WHOM COPIES OF THE DRAFT ENVIRONMENTAL STATEMENT WERE SENT...................

8-1 i 9 RESERVED FOR STAFF RESPONSES TO COMMENTS ON THE DRAFT ENVIRONMENTAL STATEMENT.............................

9-1 i

APPENDICES APPENDIX A CULTURAL RESOURCES: LETTER FROM STATE HISTORIC PRESERVATION i

0FFICER l

APPENDIX B EXAMPLES OF SITE-SPECIFIC DOSE ASSESSMENT CALCULATIONS APPENDIX C RESERVED FOR COMMENTS ON THE DRAFT ENVIRONMLNTAL STATEMENT Humboldt Bay Unit 3 DES viii i

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l 1 INTRODUCTION

1.1 Background

Humboldt Bay Power Plant Unit 3 received a construction permit on October 17, 1960. Provisional Operating License DPR-7 was issued in August 1962 arid com-mercial operation began in August 1963. On July 2, 1976, Unit 3 was shut down for refueling and seismic modifications. In 1983, the licensee (Pacific Gas '

and Electric Company) concluded that the seismic and TMI modifications

• required for restart were uneconomical and decided to decommission the plant.

By letter dated July 30, 1984 (Schuyler, 1984), the licensee proposed (1) to amend License DPR-7 to possess-but-not-operate status; (2) to delete certain license conditions related to seismic modifications required before the NRC would authorize a return to power operation; (3) to revise the Technical Specifications to reflect the possess-but-not-operate status; (4) to decommission Humboldt Bay Unit 3 in accordance with the plan included with the submittal; and (5) to extend License No. DPR-7 for 15 additional years to November 9, 2015 to be consistent with the decommissioning plan.

In response, the staff issued License Amendment 19 on July 16,1985(NRC,1985) revising License DPR-7 to possess-but-not-operate status (Item 1 above). Those items that are a necessary part of the decommissioning plan will be done in  !

conjunction with the issuance of the Safety Evaluation Report and Final Environ-mental Statement (FES). All these actions will be performed in adherence with ,

the principle of keeping occupational radiation exposures as low as reasonably achievable (ALARA). l To support the license amendment request, the licensee submitted an Environ-mental Report (Schuyler, 1984). In response, the staff has prepared this Draft Environmental Statement (DES) as required by Title 10 of the Code of Federal l Regulations Part 51.20(b)(5) (10 CFR 51.20(b)(5)), " Criteria for and Identifica-tion of Licensing and Regulatory Actions Requiring Environmental Impact l Statements." After receipt and consideration of any comments on the DES, the

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staff will issue a FES.

The Notice of Intent (NOI) for the DES was published in the Federal Register (Vol 49 No. 213, November 1, 1984). In accordance with 10 CFR 51.26, a public scoping meeting was held in Eureka, California, on December 4,1984 (Zwolinski, 1984). This DES considers the issues raised by comments on the DES scope received in response to the NOI and the public scoping meeting.

This DES addresses the occupational, public health, and environmental impacts of the licensee's proposal to decommission the unit by the safe storage (SAFSTOR) mode for 30 years, followed by removal of residual radioactivity.

• Modifications necessary to comply with requirements imposed after the accident at Three Mile Island (TMI) Unit 2.

Humboldt Bay Unit 3 DES 1-1 l

The proposed 30-year SAFSTOR period would require a 15-year extension of the license to allw a full 30 years of storage because the present expiration date of the license is November 9, 2000. This DES evaluates the SAFSTOR option; there, fore, it also evaluates the proposed 15-year extension of the license.

1.2 Proposed Action The proposed action would permit safe storage (SAFSTOR) of Humboldt Bay Unit 3 and delayed dismantling of the unit after a 30-year safe storage period (DELAYED DECON). This action is needed to provide for safe control of the residual radio-activity to ensure the protection of the health and safety of the public and the environment until the radioactivity is removed from the site. The spent fuel pool will store 390 used fuel assemblies and 18 in-core fission chambers until the Department of Energy (DOE) has a permanent Federal repository for spent fuel.

The licensee has provided a preliminary dismantling plan (Schuyler,1984) that will be the basis for the final dismantling plan. The final plan, which will support the application for termination of the unit's license, will be provided near the end of the 30-year SAFSTOR period. .

1.3 Decommissioning Alternatives The purpose of decommissioning a nuclear facility is to take the facility safely from service and to remove the associated radioactivity effectively from the environment so that the facility can be released for unrestricted use. A licensee can propose to decommission a nuclear power plant using one of three methods: DECON, ENTOMB, or SAFSTOR. Each of these is addressed below, as well as the no-action alternative.

1.3.1 DECON In the DECON method, equipment, structures, and those portions of the facility containing radioactive contaminants are removed or decontaminated to a level that permits the property to be released for unrestricted use shortly after operations stop. This alternative is not presently feasible for Humboldt Bay Unit 3 because spent fuel assemblies will be stored on the site until a permanent Federal repository is ready to receive them. (A Federal repository is not likely to be ready to receive spent fuel before 1998.) After a 30-year -

custodial safe storage period (SAFSTOR), Humboldt Bay Unit 3 will be dismantled and the site will be decontaminated and released for unrestrrcted use (delayed DECON).

1.3.2 ENT0MB The ENT0MB alternative involves encasing radioactive contaminants in a struc-turally long-lived material, such as concrete. The entcabed structure is appro-priately maintained, and there is continued surveillance until the radioactivity is removed from the site or decays to a level that pennits unrestricted use of Humboldt Bay Unit 3 DES 1-2

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' the property. Long-lived radionuclides such as niobium-94 are likely to be present in the reactor vessel so that waiting for decay would be impractical.

For entombment in some cases, there may be no need for a full-time onsite security guard force and less radiation monitoring and environment surveillance would be required because all radioactive material is contained within the

' l entombment barrier. However, in this case, because the spent fuel will remain on the site until a Federal repository is ready to accept the spent fuel, a full-time security force and adequate radiation monitoring and environmental i

surveillance would be required. Thus, the need for these spent fuel storage safety provisions and the presence of long-lived radionuclides-makes it imprac-tical to entomb Humboldt Bay Unit 3. The entombment structure may also fail as a result of seismic events with a potential for a release of radioactivity.

Entombment is not, therefore, a reasonable decommissioning alternative.

1.3.3 SAFSTOR The SAFSTOR alternative involves placing a nuclear facility in a safe condition and maintaining it in that state until it is dismantled and all remaining radio-active materials that would restrict use are removed. The facility may be left intact except that all fuel assemblies should be removed from the reactor and l

radioactive fluids and wastes should be removed from the site. 1 The licensee selected the SAFSTOR alternative for three reasons: I l

(1) It is the most cost-effective of alternatives available while there is no Federal repository for spent fuel. i (2) It would incur lower occupational exposure.

(3) It allows radionuclide decay over time, so that when final dismantling takes place, occupational radiation exposures are reduced.

Use of SAFSTOR would include the storage of the spent fuel assemblies at the Humboldt Bay Unit 3 spent fuel storage pool. 10 CFR 51.23(a) states: "The Commission has made a generic determination that for at least 30 years beyond the expiration of reactor operating licenses no significant environmental impacts w'll result from the storage of spent fuel in reactor facility storage pools or itdependent spent fuel storage installations located at reactor or away-from-reactor sites" (49 FR 34658). Moreover, storing spent fuel assemblies at Humboldt Bey for the 30-year TAFSTOR period is safer and more cost effective than other alternatives, when handling and transshipment operations are considered. Seismic considerations for this requested alternative are discussed in Sections 3.2.3.4 and 3.2.3.5.

Other alternatives for spent fuel that were evaluated but were found to be not effective are (1) ship spent fuel to Diablo Canyon and dismantle (DECON) or SAFSTOR Humboldt Bay Unit 3 i

Humboldt Bay Unit 3 DES 1-3

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(2) ship spent fuel to a Federal interim storage facility and dismantle (DECON)-

t or SAFSTOR Humboldt Bay Unit -3

-(3) ship spent fuel to a reprocessing facility and dismantle (DECON) or SAFSTOR' l Humboldt Bay Unit 3 (4) construct an independent spent fuel storage installation (ISFSI) at a site i

away from Humboldt Bay Unit 3 and dismantle-(DECON) or SAFSTOR Humboldt i Bay Unit 3 The first alternative, to transship spent fuel to the Diablo Canyon spent fuel facility, would provide only short-term storage of Humboldt Bay Unit 3 fuel assemblies. Use of this alternative also adversely affects the availability of extended spent fuel storage to meet the needs of Diablo Canyon. This alter-native would require a separate licensing action, and there is some. uncertainty about the availability and timely implementation of this alternative. In addi-i tion, the licensee made a cormnitment at an NRC Atomic Safety and Licensing Board l

hearing that the Diablo Canyon spent fuel storage pool will only be used to store fuel assemblies from Diablo Canyon Units 1 and 2. Thus, this alternative is not available.

t The second alternative is the shipment of the Humboldt Bay Unit 3 spent fuel to -

a Federal interim storage (FIS) facility. Under the Nuclear Waste Policy Act l

of 1982 (NWPA), the Federal government has the responsibility to provide not l

more than 1900 metric tons of capacity for the interim storage of spent fuel.

! The impacts of storing spent fuel at an FIS facility fall within-those already assessed by the NRC in NUREG-0575 (August 1979). In passing the NWPA, Congress detennined that the owners and operators of nuclear power. stations have the primary responsibility for providing interim storage of spent nuclear fuel.

In accordance with the NWPA, shipping spent fuel to an FIS facility is a last-resort alternative. Therefore, as long as the licensee can pursue licensable .

alternatives that can be reasonably available in a timely manner, this.alterna-tive is not considered pertinent.

The third alternative is to ship the spent fuel to a reprocessing facility.

However, reprocessing the Humboldt Bay Unit 3 spent fuel is not a viable alter-native-because there is no operating commercial reprocessing facility in the United States, nor is there the prospect for one in the foreseeable future.

The fourth alternative is to construct an independent-spent fuel storage in-stallation (ISFSI) at a site away from Humboldt Bay Unit 3. The ISFSI could be l a dry type or a pool type. The only difference between this alternative and r

storage at Humboldt Bay would be that an ISFSI away from the reactor site would

, require offsite shipment of spent fuel and construction of a fuel handling facility. Thus, this alternative would be more costly than SAFSTOR, would have '

! the additional environmental impacts associated with offsite transportation of.

spent fuel, and would require seismic considerations of' the ISFS!. 10 CFR Part 51.52 establishes the conditions for offsite transportation of fuel and -

radioactive wastes. The staff has generically assessed the impacts for this l

T Humboldt Bay Unit 3 DES 1-4 l

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i alternative and found that storing light-water-reactor spent fuel in pools has an insignificant impact on the environment and that dry storage appears to be environmentally acceptable (NUREG-0575). However, there is some doubt about the availability of alternative sites and the time it would take to construct an ISFSI (about 5 years). Therefore this alternative would not meet the licensee's immediate need for storing spent fuel from Humboldt Bay Unit 3, and it would have greater environmental impact than onsite fuel storage.

1.3.4 No Action The licensee has determined that the facility will not be operated again because of the high cost of modifications needed to meet NRC safety requirements for operation.

With the facility permanently shut down, the alternative of not proceeding WP..

a decommissioning plan could introduce uncertainty about the types of actions needed to ensure protection of the health and safety of the public and the envi-ronment. Although the licensee currently holds a possession-only license, the facility Technical Specifications have not been revised to reflect the SAFSTOR status. Thus, with no action, there could be a greater potential for release of radioactive material from systems and tanks containing contaminated water as a result of system deterioration or a seismic event. The decommissioning plan ensures that contaminated water is removed from these systems and tanks, except for the spent fuel pool and the associated radwaste system. Eventually the resi-dual radioactivity would have to be removed and, if no advance plans or prepara-tions for this were made, the costs in dollars and the potential exposures to the workers and the public would likely be higher.

1 Humboldt Bay Unit 3 DES 1-5

2 DESCRIPTION OF PLANT AND PROPOSED DECOMMISSIONING PLAN .

2.1 Humboldt Bay Power Plant Unit 3 Humboldt Bay Power Plant Unit.3 is a natural circulation 65-MWe boiling water reactor that was operated by Pacific Gas and Electric Company (PG&E) (Pacific Gas and Electric, 1961). The plant is located about 6.4 km (4 miles) southwest of the city of Eureka, Humboldt County, California. The plant was operated commercially for the production of electrical energy from August 1963 to July 1976 under License DPR-7.

The site plan is shown in Figure 2.1. Humboldt Bay Unit 3 is located alongside two fossil-fueled power plants (Humboldt Bay Units 1 and 2). Two gas turbine units are designated mobi'le emergency power plants. The plant structures and equipment are shown in Figures 2.2 and 2.3. The reactor primary containment, located below grade, consists of the drywell vessel, which contains the reactor, and the suppression chamber. The drywell and suppression chamber are located inside a concrete caisson. The refueling building encloses the space above the caisson. The refueling building contains the spent fuel storage pool and the new fuel storage vault in addition to the reactor caisson. Next to the refuel-ing building are the power building and turbine pedestal. The power building contains the condenser, feedwater and condensate systems, steam cycle auxiliary systems, and the control room. The turbine generator is located on the turbine pedestal. Liquid and solid wastes are processed in the radwaste treatment facilities.

The fuel was removed from the reactor early in 1984. At the present time the spent fuel pool contains 390 partially or completely spent fuel assemblies and 18 in-core fission chambers. These units will remain in storage until the DOE has a repository ready to' receive them. The fuel fission product inventory is approximately 1.1 x 108 curies (as of July 1985). 'A cover (a contamination control barrier) will be installed over the spent fuel pool.to mitigate the spread of small amounts of contamination that may be released from the pool and to provide protection against objects dropping into the pool. The pool contami-nation control barrier will be tied into a radiation-monitored ventilation system.

The inventory of activation products in the plant is about 1.0 x 104 curies (as of July 1985). Approximately 67 curies (July 19i) on contaminated surfaces are also within the plant inventory. During initial operation of the plant (March 1966), spent fuel pool leakage was detected. Although this leakage was attenuated by the installation of a stainless steel liner, the leakage produced a small amount of soil contamination. A test in January 1985 measured the liner leak rate. Liquid samples were taken from the spent fuel pool and liner gap to determine tritium activity. The spent fuel pool tritium activity was 686 pCi/mL, while that of the gap was 30.5 pCi/mL. (Groundwater leakage diluted the spent fuel pool leakage into the gap.) The gap tritium level indicates that the. spent fuel pool leak rate into the liner gap is less than 0.45 L (0.12 gallon) per day. Pumps keep water level in the liner gap lower Humboldt Bay Unit 3 DES 2-1

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than the water-level in the pool and the groundwater level. The water from the liner gap is pumped to the radwaste system.

2.2. Decommissioning Plan The Humboldt Bay Unit 3 decommissioning plan proposed by the licensee is SAFSTOR for a period of 30 years followed by DECON. SAFSTOR requires that a nuclear facility be placed and maintained in such a condition that the nuclear facility can be safely stored and subsequently decontaminated (deferred decontamination (DECON)). DECON requires that equipment,. structures, and portions of a facility and site containing radioactive contaminants be removed or decontaminated to a level that permits the property to be released for unrestricted use.

In preparation for SAFSTOR, the licensee is completing several tasks that are permitted under the operating license (DPR-7) and the recently issued possess-but-not-operate amendment. These activities include (1) removing irradiated fuel assemblies and in-core fission chambers and trans-ferring them to the spent fuel storage pool where they will remain until DOE has a permanent Federal repository to receive them (2) draining the reactor vessel and reactor cooling system (3) processing, packaging, and shipping radioactive waste to a low level waste disposal facility (4) removing certain pipe sections and components that are significant contri .

butors to dose rates in work areas (to implement the ALARA program)

(5) decontaminating components and the facility Approval of the decommissioning plan and the extension of the possess-but-not-operate license will allow decommissioning Humboldt Bay Unit 3 in the SAFSTOR mode for a period of 30 years.

When approval of SAFSTOR is obtained, the licensee will perform the following activities:

(1) complete _the layup of systems not required during SAFSTOR (2) complete the modifications of the spent fuel storage pool facilities, (3) complete modifications of the plant security system (4) complete decontamination of systems and components (5) process, package, and ship the radioactive waste generated by SAFSTOR activities (6) when the activities to place Unit 3 into SAFSTOR are complete, perform.

baseline radiological surveys Humboldt Bay Unit 3 DES 2-5

When the 30-year SAFSTOR phase is complete, the licensee plans to dismantle (DECON)

Humboldt Bay Unit 3. Near the end of the SAFSTOR phase, the licensee will submit the DECON plan for staff review and approval. The objective of DECON is to dismantle the facility in a way that will ensure the health and safety of the public and maintain occupational exposure ALARA, so the site can be released for-unrestricted use. The licensee has initiated action with the California Public Utilities Commission to set aside and accrue funds for DECON activities.

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Humboldt Bay Unit 3 DES 2-6 .,

l 3 ENVIRONMENTAL IMPACTS 3.1 Assessment of Nonradiological Impacts of Decommissioning 3.1.1 Socioeconomic and Cultural Resources The socioeconomic impacts of SAFSTOR maintenance of Unit 3 are expected to be minor (Schuyler,1984). No impacts to cultural resources are anticipated.

The permanent plant staff required for SAFSTOR maintenance of Unit 3 and the operation and maintenance of the fossil fueled units and gas turbines is ex-pected to total 73 PG&E employees. The plant staff for the past 5 years has varied between 75 and 82 persons. The number of temporary additional employees (contractor and PG&E) needed for the 1- to 2 year period required to prepare Unit 3 for SAFSTOR is expected to vary between 7 and 15 persons. Because of the small number of temporary workers involved, the impact on the communities in which they reside and on traffic is expected to be minimal.

The total annual labor costs for the Humboldt Bay plant are estimated to be 52.77 million (1984 dollars), of which $0.22 million is allocated for Unit 3 during SAFSTOR. The average annual dollar amount of purchases of materials and supplies resulting from SAFSTOR activities is expected to be $20,000 (1984 dollars). The purchases are expected to be made in Humboldt County.

No impacts to any properties in or eligible for the National Register of His-toric Places are expected (see letter of agreement from State Historic Preser-vation Officer in Appendix A). ,

3.1.2 Hydrology The licensee's Environmental Report (Schuyler, 1984) was reviewed using the hydrology-related sections of the Environmental Standard Review Plan for Con-struction Permit Review of Nuclear Power Plants (NUREG-0555).

On the basis of its review, the staff concludes that there will be no measur-able nonradiological hydrologic impacts, including water use impacts. The pri-mary noncooling water supply for the Humboldt plants is obtained from two fresh water wells, one on site and one just off the site. The use of this water by Humboldt Unit 3 during SAFSTOR will be a small fraction of the use by Units 1 and 2.

3.1.3 Aquatic Resources '

Humboldt Bay receives very little fresh water inflow. Salinity remains high year round, effectively limiting withdrawal uses. Although the tidal range is moderate, about 1.2 to 1.8 m (4 to 6 feet), flushing of the bay is great with about 44% exchange of water on each tidal cycle. The bay is broad and shallow Humboldt Bay Unit 3 DES 3-1

with deep channels. Diverse habitat types are found in the bay, although the most predominant are extensive mud flats.

Water for cooling the condensers for the three units at the site is transported from the bay by a common intake canal and is returned by a combined discharge canal. Potable water is obtained from wells. All discharges from the nuclear unit are directed to the discharge canal where they mix with cooling water dis-charges from the two fossil-fueled units.

During the SAFSTOR period, the only industrial water system to be used will be the spent fuel pool cleanup system. Because of the long time that has elapsed since the fuel was removed from the reactor, it is no longer necessary to oper-ate the fuel pool cooling system. The spent fuel pool coolers will be flushed and drained when they are removed from service.

3.1.4 Terrestrial Resources The types of terrestrial ecosystems bordering the Humboldt Bay site are de-scribed in Section 4.1.5.2 of the Environmental Report. These ecosystem types are situated as follows: to the north and east, the plant borders fresh water marsh and agricultural grazing lands; to the south are salt marsh and fresh water marsh areas; toward the bay are mud flats, sand flats, a few eelgrass beds, and numerous substrates created by humans; and within the bay shallows to the north are brackish marshes, mud flats, sand flats, beach sands, sand islands, and a woody riparian community on Indian Island.

There will be no decommissioning activity in the area occupied by the natural ecosystem types, nor is there likely to be any change in their function that would be affected by the decommissioning process. Therefore, the staff con-cludes that there will be no impact on terrestrial resources.

3.1.5 Endangered and Threatened Species There are no resident terrestrial or aquatic species in the area of the site that are Federally listed as endangered or threatened species (Environmental Report Section 4.1.5). However, the Brown Pelican (Pelecanus occidentalis) and the Peregrine Falcon (Falco peregrinus), which are on the Federal list of endan-gered species, occasionally visit the Humboldt Bay area. No mechanism for impacting these two species is evident. Therefore, decommissioning is not likely to result in any detrimental impacts to these species.

3.1. 6 Land Use The decommissioning of the Humboldt Bay Unit 3 by SAFSTOR will not affect land use on or in the vicinity of the plant site. The only related new construction on the site will be the installation of a building around the exposed parts of the radioactive waste processing system (Environmental Report Section 10.5-10).

The construction of this building will not require the disturbance of any pre-viously undisturbed land.

The decommissioning will not affect any offsite land uses. Environmental Report Section 4.1.5.2.4 states that the U.S. Army Corps of Engineers is mitigat-ing several marshes to enhance approximately 14.2 ha (35 acres). Mitigation Humboldt Bay Unit 3 DES 3-2

involves breaking existing dikes, allowing tide currents to move into the area.

Mitigation will provide wildlife--primarily migratory birds--with refuge and feeding areas. These marshes are located at the northern end of Arcata Bay, l and the licensee is not involved with this project.

l 3.1.7 Water Use During the SAFSTOR period, the only discharge from Humboldt Bay Unit 3 will be an occasional release from the liquid waste treatment system. This.relatively clean water will be piped to the discharge canal where it will ' e.further di-luted with the cooling water flow from the two fossil-fueled units. The tidal flushing action in the bay will further dilute and disperse these intermittent discharges. Thus, although some metallic ccrrosion products may at times be present in the discharge, they are not expected to occur at toxic levels. The State of California Regional Water Quality Control Board has determined that discharge levels are within the limits of the National Pollution Discharge Elim-ination System (NPDES) discharge permit (Environmental Report Section 4.2.4.1.2),

as revised.

3.1.8 Unavoidable Environmental Impacts The Humboldt Bay Unit 3 facility will occupy the present site for approximately 30 years, thus making that oroperty unavailable for other uses for that period of time. Restricted land use for 30 years is the only known unavoidable envi-ronmental effect of the planned decommissioning. The proposed decomissioning alternative, as well as others, is discussed in Section 1.3 of this DES.

3.1.9 Local Short-Term Uses versus Long-Term Productivity i

The site is now being used for power production with the operation of the two adjacent fossil-fired electrical generators. Tne licensee has no plans for i this site other than electrical power production for the 30 years involved in j the storage (SAFSTOR) of Humboldt Bay Unit 3. Therefore, there is no conflict '

in short-term uses versus long-term productivity.

3.1.10 Irreversible and Irretrievable Comitments of Resources l

The proposed 30 years of SAFSTOR followed by dismantling would not involve the l i

comitment of any significant amount of resources. In fact, there would likely l be less volume of radioactive waste to dispose of at the end of the SAFSTOR l period in contrast with the amount present with immediate DECON because of l radioactive decay. With less volume of radioactive waste, the required burial l area at a waste burial site would be reduced.

3.2 Assessment of Radiological Impacts of Decomissioning The radiological impacts of 30 years of SAFSTOR consist primarily of (1) the environmental impacts of releases of liquid and gaseous radioactive effluents.

(2) the occupational radiatfor, exposure of workers involved in decomissioning and SAFSTOR maintenance, and (3) radiation exposure resulting from the trans- ,

I portation of radioactive waste from the plant site for disposal. There is 1 also a potential for additional impacts as a result of possible accidents at the plant site.

Humboldt Bay Unit 3 DES 3-3 n-.

During normal SAFSTOR operations, small quantities of radioactivity (fission, corrosion, and activation products) will be released to the environment. As required by the National Environmental Policy Act (NEPA), the staff has deter-mined the estimated dose to members of the public outside of the plant bounda-ries as a result of the radiation from these radioisotope releases and relative to natural background radiation dose levels. These estimated doses are detailed in Appendix B.

Little transportation of radioactive waste from the site during SAFSTOR will be required. The staff considers the licensee's estimate of 0.02 person-rem of public exposure for the 30 year period to be reasonable.

To estimate the environmental radiological impacts from delayed DECON, the staff is using the estimates in NUREG/CR-0672: 0.0055 millirem to the total body and 0.04 millirem to the lung for the maximally exposed individual, and 0.003 person-rem total body and 0.05 organ-rem to the lung for the papulation within 80 km (50 miles) of the plant boundary.

3.2.1 Occupational Radiation Exposure During the 30 year SAFSTOR period, maintenance and waste management will be the principal contributors to occupational radiation exposure. The licensee has estimated that maintenance will account for about 47 person-rems and waste management for about 36 person-rems. The licensee estimated that monitoring and surveillance will add another 8 person-rems, for a total of 91 person-rems.

The licensee is committed to maintain occupational exposure ALARA during SAFSTOR.

Either during or at the end of the SAFSTOR period, the spent fuel will be shipped off the site. The licensee estimated that this activity will result in exposures of 4.6 person-rems to workers plus about 0.3 person-rem to the public.

During the decontamination and dismantling of the plant following SAFSTOR, there will be an occupational radiation exposure of about 86 person-rems, plus a public exposure of about 0.4 person-rem when materials are transported off the site. The licensee estimates that total occupational exoosure for SAFSTOR with delayed DECON will be about 177 person-rems. The staff has reviewed the estimates and considers them reasonable.

In estimating the health effects resulting from both offsit.? and occupational radiation exposure as a result of decommissioning this facility, the staff used somatic (cancer) and genetic risk estimators that are based on widely accepted scientific information (National Academy of Sciences, 1972, 1980). The esti-mates of the risks to workers and the general public are based on conservative assumptions (that is, the estimates are probably higher than the actual number).

The following risk estimators are used to estimate health effects: 135 poten-tial deaths from cancer per million person-rems -and 220 potential cases of all forms of genetic disorders per million person-rems.

The cancer mortality risk estimates are based on the " absolute risk" model de-scribed in BEIR I (National Academy of Sciences, 1972). Higher estimates can be developed by use of the " relative risk" model, along with the assumption that risk prevails for the duration of life. Use of the relative risk model wo'uld produce risk values up to about four times greater than those used in this report. The staff regards the use of the relative risk model values as a Humboldt Bay Unit 3 DES 3-4 r

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reasonable upper limit of the range of uncertainty. The lower limit of the range would.be zero because there may be biological mechanisms that can repair damage caused by radiation at low doses and/or dose rates. The number of poten-tial . cancers would be approximately 1.5 to 2 times the number of potential fatal

( cancers, according to BEIR III (National Academy of Sciences, :1980).

l l Values for genetic risk estimators range from 60 to 1100 potential cases of-I all forms of genetic. disorders per million person-rems (BEIR III). The value i of 220 potential cases of all . forms of- genetic disorders per million person-j rems is equal to the sum of the geometric means of the risk of specific genetic =

defects and the risk of defects with complex etiology. '

! The preceding values for risk estimators are consistent with the recommenda-tions of a number of recognized radiation-protection organizations, such as i the International,Cominission on Radiological Protection (1977), the National i Council on Radiation Protection and Measurements (1975), the National Academy

of Sciences (BEIR III,.1980), and the United Nations Scientific Committee on the Effects of Atomic Radiation (1982).

} The risk of potential fatal cancers in the exposed work force population at the i Humboldt Bay facility is estimated as follows: multiplying the plant-worker j population dose (about 177' person ~ rems) by the somatic risk estimator, the staff j estimates that about 0.02 cancer death may occur in the total exposed popula-i tion. The value of 0.02 cancer death means that the. probability of 1~ cancer-

! death over the lifetime of the entire work-force as a result of . facility decom-

] missioning is about 2 chances in 100. The risk of potential genetic disorders j attributable to exposure of the work force is a risk borne by the progeny of l the entire population and is thus properly considered as part of the risk to j the general public.

i i Multiplying the dose to the general population from exposure to radioactive j effluents and transportation of fuel and waste from the decomissioning of this l facility (16 person-rems) by the preceding somatic risk estimator, the staff i estimates that about 0.002 cancer death may occur in the' exposed population.

j The significance of this risk can be determined by comparing it to the total incidence of cancer death in the population of the United States. Multiplying the estimated population of the United States for the year 2000 (260 million persons) by the current incidence of actual cancer fatalities (20%), about 52 million cancer deaths from all causes are expected (American Cancer Society, 1978).

1 For purposes of evaluating the potential genetic risks, the progeny of workers

are considered members of the general public. However, according to para-1 graph 80 of ICRP 26(1977), it is assumed that only about one-third of the oc-cupational radiation dose is received by~ workers who have offspring after the 1

workers' radiation exposure. Multiplying the sum of the dose to the population i from ex

plant (posure to radioactivity 16 person-rems) attributable and the to the decommissioning estimated effective of the expo-dose from occupational i sure (one-third of 177 person-rems) by the preceding genetic risk ' estimators, j the staff estimates that about 0.02 potential genetic disorder may occur in all i future generations of the exposed population. . BEIR III indicates that the mean persistence of the two major types of genetic disorders is about 5' generations and 10 generations, respectively. Thus, .in the following analysis, the risk of

j potential genetic disorders from the storage'and. decontamination of.the plant Humboldt Bay Unit 3 DES 3-5 l s 5

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i I is conservatively compared with the risk of actual genetic ill health in the-

first 5 generations, rather than the first 10 generations _ Multiplying the es- i

timated population within 80 km (50 miles) of the plant-(*130,000 persons in ,

the year-2000) by the-current incidence of actual genetic ill health in each generation (*11%), about 71,000 genetic abnormalities from all cases are expec-

ted in the first five generations of the population within 80 km (50 miles) of 1- the plant (National Academy of Sciences, 1980).

The risks to the general public from exposure to radioactive effluents and ,

, transportation of fuel and wastes from the facility are very small fractions of j the estimated normal incidence of cancer fatalities and genetic abnormalities.

On the basis of the preceding comparison, the staff concludes that the risk to.

I the public health and safety from exposure to radioactivity associated with'the j

decommissioning of the facility will be very small.

= L I 3.2.2 Radioactive Waste Management Systems'

! Radioactive liquid waste generated during the SAFSTOR period will be processed j and disposed of. The expected sources of radioactive liquid wastes include j spent fuel pool liner leakage, spent fuel pool recirculation pump packing leak '

j age, waste water from ongoing decontamination activities, hot lab waste,:and rainwater runoff from contaminated areas.

l A building will be erected to enclose the exposed portions of the radioactive

waste processing system. This building will prevent rainfall contamination and thus eliminate a need for processing contaminated rainfall. During the SAFSTOR 1 period, the only significant activities involving radioactivity will be associ-l ated with the decontamination of systems and components, the operation and main-tenance of the spent fuel storage pool, and the processing of wastes resulting from these operations. These activities will account for essentially all re-2 i leases of radioactive materials.

L I The liquid radwastes from the spent fuel pool, decontamination a'ctivities, and the hot lab will be collected and sampled. If contamination is present or sus-pected in a batch, the batch will be processed more before it'is discharged to i the plant discharge canal. Processing consists of filtration and, if necessary,

! treatment by the radioactive waste evaporator or a demineralizer, depen' ding on '

I the chemical composition of the waste. - After processing, the liquid effluent

} will be sampled and released to the plant discharge canal where it will be di-l luted with circulating water from Unit 1 and,or Unit 2 before it is discharged i

i- to Humboldt Bay, +

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The liquid radioactive waste concentrated by the evaporator will be accumulated

in the concentrate waste tanks until one tank is filled. A contractor will then i analyze and solidify the concentrated liquid waste using portable equipment. '

Spent cartridge-type filters and filter crud will be packaged in drums and stored

' in a shielded area. When a sufficient quantity of waste has been accumulated, a contractor will analyze and solidify / encapsulate it using portable equipment. ,

p Dry active waste and contaminated tools, equipment, lumber o and soil will be-i packaged for shipment and stored until they are shipped off site for disposal.

! The handling of activated components will be similar to-the handling of spent =

! filter or dry active waste, as appropriate. After.proce'ssing and handling as above, all solid wastes will be stored on the site until'they are shipped, in

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appropriate containers, for. disposal at a licensed disposal site. The solid

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-waste vault, the low-level waste storage building, and the solid waste handling building will be used to store solid wastes before they are shipped off the site for disposal. ~

The ventilation exhausts from the refueling building, hot lab, hot machine shop, and the radwaste treatment building operating area will be routed to the moni-

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tored plant ventilation spstem for release from the 250-foot-high plant stack.

No treatment is provided by this system for normal releases. - A cover with a controlled ventilation exhaust will be installed over the spent fuel pool. Con-trolled ventilation is not provided for the solid waste storage vault, the low-level waste storage building, or the solid waste handling building.

The operation and maintenance of the spent fuel storage pool and the processing of wastes resulting from the spent fuel pool have continued since the plant ceased commercial operation in July 1976. The calculated annual gaseous and liquid effluent releases over the 30 year SAFSTOR period were evaluated using values given in the Humboldt Bay Power Plant semiannual reports on radio-active effluent releases and waste disposal covering the post-shutdown years 1977 through 1983. On the average, actual releases are expected to be less than the calculated releases (listed in Tables 3.1 and 3.2) as a result of radioactive decay over the 30 year SAFSTOR period.

The staff's detailed evaluation of the radwaste system and its capability to accommodate the solid waste expected will be in the SER. The licensee has estimated that, on the average, approximately 1 m3 (36 ft3) of resins contain-ing 0.1 curie of radioactivity, 2 m3 (75 ft3) of evaporator bottoms containing 0.01 curie of radioactivity, and 4 m3 (150 ft3) of dry, active wastes contain-ing 0.0015 curie of radioactivity (all mainly Cs-137 and Sr-90) will be generated annually to be processed, stored, and shipped to a licensed disposal site. The packaging and shipping of these wastes will be in conformance with the applicable requirements of 10 CFR 20, 61, and 71 and 49 CFR 170 to 178.

The licensee has proposed: (1) Technical Specifications limiting release rates for radioactive materials in liquid and gaseous effluents and (2) routine monitoring and measurement of principal release points to ensure that release rates are in conformance with the regulations.

Releases of radioactive materials during final decontamination and dismantling at the end of the 30 year SAFSTOR period will result primarily from waste man-agement operations. Atmospheric releases will be insignificant. Releases in liquid effluents during the 4 year DECON period are estimated to be about 0.6 curie of gross beta gamma and gross alpha and 6 curies of tritium. Liquid radwastes will be treated, as necessary, before they are released, and the solid radwastes from this treatment will be processed before they are shipped off the site for disposal. Radioactive solid wastes will be analyzed, processed, and packaged to meet the requirements for transportation and final disposal.

3.2.3 Postulated Accidents In assessing the impacts of postulated accidents, the staff has reviewed the licensee's submittals (Schuyler, 1984; Shiffer, February, April, and July, 1985) related to decommissioning and to maintaining Humboldt B'y a Unit 3 in SAFSTOR Humboldt Bay Unit 3 DES 3-7 l

f Table 3.1 Calculated releases of radioactive materials in liquid effluents from Humboldt Bay Unit 3 during the 30 year SAFSTOR period Nuclide mci /yr Nuclide mci /yr, Corrosion and activation products Fission products, continued Cr-51 0.004 I-131 0.004 '

Mn-54 0.4 Xe-133 0.004 Co-58 0.004 Xe-135 0.004 Co-60 28 Cs-134 11 Zn-65 0.4 CS-137 110 Zr/Nb-95 0.004 Ba/La-140 0.004 Np-239 0.004 Ce-141 3.2 Ce-144 4 Fission products Others Sr-89 0.004 Sr-90 0.3 Tritium 83 Mo-99 0.004 Gross alpha 0.42 Tc-99m 0.004 Table 3.2 Calculated releases of radioactive materials in gaseous and particulate effluents from Humboldt Bay Unit 3 during the 30 year SAFSTOR period Nuclide mci /yr Nuclide mci /yr Kr-83m 0.004 I-133 0.004 Kr-85 0.920 I-135 0.004 Kr-85m 0.004 H-3 40 Kr-87 0.004 Mn-54 0.019 Kr-88 0.004 Co-60 0.220 Kr-89 0.004 Sr-89 0.004 Xe-133 0.004 Sr-90 0.0081 Xe-133m 0.004 Sb-125 0.0047 Xe-135 0.004 Cs-134 0.014 Xe-135m 0.004 Cs-137 0.061 Xe-137 0.004 Ba/La-140 0.004 Xe-138 0.004 Ce-144 0.025 I-131 0.004 Gross alpha 0.004 Humboldt Bay Unit 3 DES 3-8

for a nominal 30 years before its ultimate dismantling. The review was con-ducted in accordance with Regulatory Guide 4.2, Revision 2 and NUREG-0612 and NUREG-0554 with respect to accident assumptions, and in accordance with the

, Standard Review Plan for the Safety Review of Nuclear Power Plants (NUREG-0800) l Section 9.1.2 with respect to criticality.

The SAFSTOR mode does not' allow power operation, criticality, or fuel loading.

Because the license restriction of " possession only" is in effect during SAFSTOR, the staff assessed only non-reactor core accidents for low probability scenarios.

In the SAFSTOR mode, all of the spent fuel (390 assemblie's) is stored in the spent fuel pool. Boral neutron-absorbing blankets surround each assembly to ensure subcriticality after any event that may result in a rearrangement of stored spent fuel assemblies.

3.2.3.1 Evaluation To evaluate offsite radiological consequences of potential accidents involving spent fuel stored in the spent fuel pool, the staff considered three types of hypothetical accidents: a fuel handling accident, a non mechanistic heavy load drop, and a seismically, or otherwise induced, rearrangemen' of stored spent fuel assemblies. Other hypothetical accident scenarios considered were: a non-mechanistic expulsion of all pool water and radionuclide contaminants of the pool water to the atmosphere, a spent fuel pool rupture, and an uncontrolled release of all' contents of the liquid radwaste tanks to the discharge canal.

These are discussed below.

3.2.3.2 Fuel Handling Accident The offsite radiological consequences of the drop of a spent fuel assembly con-sist almost entirely of the whole body dose resulting from the release of one-sixth of the Kr-85 gap activity contents of two stored assemblies. This is because all stored assemblies have a decay time of at least 9 years. The prin-cipal thyroid dose contributor, I-131, with an 8.05-day half-life, has decayed to negligible concentrations (as have other significant iodine radioisotopes).

Release of the long-lived isotope Kr-85, with a 10.8 year half-life, produces a (0- to 2-hour) offsite whole body dose at the exclusion area boundary of 0.3 mrem. This estimate assumes there has been damage to one row of pins in each of two assemblies, a reasonably conservative assumption, taking into account fuel assembly geometry and type. It also assumes an exclusion area boundary 50th percentile atmospheric diffusion and transport relative concentration (X/Q) of 7.7 x 10 4 sec/m3 The U.S. Environmental Protection Agency (EPA) has proposed a range of doses above which protective actions would be warranted.

These projected dose levels, known as the Protective Action Guide (PAG) levels, are 1 to 5 rems to the whole body or 5 to 25 rems to the thyroid (EPA, 1975).

The projected dose from a fuel handling accident is well below the PAG levels.

3.2.3.3 Fuel Assembly Damage Caused by Non-Mechanist'ic Heavy Load Drop or Site-Related Hazards j The 0- to 2-hour offsite radiological consequences of a non-mechanistic heavy load drop in the spent fuel pool are estimated.to be 58 millirems to the whole body.

This estimate assumes there has been damage to one row of pins in all 390 spent fuel assemblies, with a minimum conservatively assumed 9 year cooldown time.

Humboldt Bay Unit 3 DES 3-9 E *- - _ _ _ _ _._m.____

This estimate uses the same atmospheric diffusion and transport relative-concen-tration used in Section 3.2.3.2 above. Again, the thyroid dose .is estimated to '

be negligible. These consequences are also a very: small fraction of the. PAG dose levels.

On the basis of' the non-mechanistic h'eavy _ load drop . analysis,. the staff has de-termined that site-related hazards that might produce heavy falling objects do not. pose a significant environmental threat to the spent fuel: pool or its con-tents. For example, although the onsite storage of liquid propane may represent a fire or explosion hazard, ignition!or detonation of liquid propane is not a significant threat te the integrity of the spent fuel pool. .The damage potential' would be primarily in terms of the irnpact of heavy objects (e.g., nearby equip-ment or structural debris) that might fall into the spent fuel pool. :Because of the difficulty of postulating specific potential-load drops over the 30 year SAFSTOR period, for this analysis the staff assumed that the offsite-radiological consequences of a non-mechanistic heavy load drop described above bound the potential consequences of this type of hazard. Hence, the presence of_ combust-ible fuels on this site does not pose a significant-environmental threat to the spent fuel pool.

-3.2.3.4 Criticality Potential of Stored Spent Fuel Rearranged as a~ Result of Seismic or Other Mechanical Loads In a submittal of July 30,1985 (Shitfer, July 1985), -the licensee provided an analysis of the criticality features of the stored spent fuel configuration.

Both the CASMO-2E computer code, used by PG&E, and the MERIT computer code, used by the General Electric Company (GE), have been used extensivelysin pre-vious criticality analyses. PG&E has provided data to validate the use of the CASM0-2E code in the Humboldt Bay analyses, and GE has provided data to validate the use of the MERIT code. ,

To decrease the probability and mitigate the consequences of a criticality!acci-dent that would result from a heavy load drop or a seismic event, the licensee has committed to make the following spent fuel rack modifications:

~

(1) Each fuel bundle will be conta'ined in a can fabricated from a neutron-absorbing material (poison)-containing a B-10-density that precludes achieving a Keff (the effective neutron multiplication factor) greater than 0.90 for any possible configuration. The neutron- absorbing material, Boral, has been previously accepted by the staff for controlling critical-ity in spent fuel pools.

(2) Mechanical.means will be provided to prevent-separationLof the fuel bundle from the. poisoned can. -

(3) The poisoned can/ fuel bundle assembly will be stored in the "

existing fuel storage racks.

The licensee has analyzed the~effect of' varying the internal. pitch of an assembly and the distance between-stored spent: fuel ' cans. The results are consistent with staff estimates. ,

Humboldt-Bay Unit'3 DES 3-10 r

M

A The licensee's analysis of the most reactive com'bination of the spacing param-eters shows that the calculated values of Keff meet the (maximum) limiting criterion (NUREG-0800) of 0.95 with a margin greater than 0.05.

These calculations make the tacit assumption that any distortions of the racks would leave the basic geometry unaltered (i.e., the fuel rods would remain in a parallel array and be surrounced by the Boral plates)' This assumption may not be valid under all credible array-altering physical mechanisms. However, the following statements can be made about the likely effects of calculational as-sumptions and possible distortion of a spent fuel assembly geometry:

(1) The licensee assumed the presence cf fresh' fuel with no credit for the presence of gadolinium, a burnable poison. This'is conservative as even a small amount of burnup will reduce reactivity somewhat.

(2) ~ Assuming infinite length for the assemblies is conservative. Use of the

correct length would reduce K by 0.01.

eff (3) .It is very unlikely that any credible rearrangement of the stored spent fuel-by crushing under seismic or other loads would increase the reactivity of the system enough to make it critical. The licensee's analysis (Shiffer, July 1985) assumed no radial or axial neutron leakage for example, and, therefore, it is unlikely that crushing the assemblies into. a pancake geo-metric configuration (with rods still vertical) would increase the reactivity.

) Likewise, a local pile of fuel pellets (low-enrichment) is very likely to be undermoderated and subcritical.

Therefore, the staff concludes that there is a negligibly small likelihood that there it any credible means of producing criticality in the stored spent fuel array.

3.2.3.5 Non-Mechanistic Expulsion of Pool Water and Radionuclide Contaminants to the Atmosphere In the event of a large seismic event near the site, it is conceivable that 3

falling debris could cause some of the spent fuel pool water containing radio-nuclide contaminants (chiefly cobalt, cesium, and strontium) to slosh or splash through newly created building fissures or openings. To' bound the potential offsite doses resulting from such a hypothetical occurrence .the staff assumed that all radionuclide contaminants in the pool water inventory are released instantaneously and directly to the atmosphere.

The integrated source term assumed for the dose assessment was 9.2 x 10 ' curie of Co-60,1.7 curies of Cs-137, and 2 x 10 ' curie of Sr-90. Of these quantities, 1% was assumed to be inhalable. No credit was taken for washout. Using the same x/Q value used in Section 3.2.3.2 above and the methods given in Regulatory Guide 1.109, Revision 1, the staff. calculated the following offsite 50 year inhalation-initiated dose commitments: 1.8 x 10 8 millirem to the lung,

'0.35 millirem to the liver, and 6.4 x 10 2 millirem to the bone. (In this scenario, immersion doses are negligible.) These are all,very small fractions of the PAG dose levels.- i l

l Humboldt Bay Unit 3 DES 3-11

3.2.3.6 Spent Fuel Pool Rupture The consequences of a rupture in the spent fuel pool were analyzed by.the licensee and the staff. The analyses assumed the released effluent would enter the tidal-affected water table aquifer and flow down gradient toward Humboldt Bay.

The rainy season groundwater level at the spent fuel pool.is 2.7 m (9 feet).

Mean lower low water (MLLW) and the mean tide level are 1 m (3.3 feet). From estimated values of hydraulic conductivity of 3170 m/ year (10,400 feet / year) and effective porosity of 0.25, a groundwater velocity of 173 m/ year (564 feet / year) was determined. On the basis of this velocity and a distance to'Humboldt Bay from the spent fuel pool of 128 m (420 feet), a travel time of about'9 months for the effluent to enter Humboldt Bay was estimated. The geochemical properties of the site would further retard the movements of radionuclides such as cesium, strontium, and cobalt. To determine the amount of retardation, the licensee estimated distribution coefficients of 1.5 mL/g for strontium and cobalt and 20 mL/g for cesium. The staff considers these estimates to be reasonable and 0

conservative for the site.

For the release scenario, the licensee assumed-that only that effluent in the pool between the top of the pool and the mean tide level of 1 m (3.3 feet) MLLW would flow out. Although the staff does not consider the licensee's assumption conservative for all conceivable release scenarios, the staff used the licensee's estimates of amounts released for calculating reasonable doses.

The staff used a simple analytical model of contaminant flux through a vertical plane to estimate the amounts of Cs-137, Cs-134, Sr-90, and Co-60 entering Humboldt Bay. From the flux calculation and the licensee's release estimates, the staff determined Cs-137 to be the primary contributor to dose with about 3.2 x 10 2 curie of Cs-137 entering Humboldt Bay. Sr-90 and Co-60 were lesser contributors, with 5.2 x 10 4 curie of Sr-90 and 8.7 x 10 4 curie of Co-60 entering Humboldt Bay. For dose calculations, the radionuclides were assumed to remain in Humboldt Bay for 1 year. Using estimates of the amount of human

)

food consumed from the commercial fish catch data, the staff determined that a rupture of the spent fuel pool would result in a total population dose of 0.133 person-rem (Shiffer, July 1975, and RG 1.109), implying an average indi-vidual dose commitment less than that of background radiation. Doses to the population as a result of water recreational activities would be negligible compared with those resulting from seafood consumption.

If the entire inventory of radionuclides in the spent fuel pool were assumed to be released, the resulting population dose wo'uld still be less than 1 person-rem.

3.2.3.7 Uncontrolled Release of Radwaste Tank Contents l

The licensee presented an analysis of.an uncontrolled release from'the two con--

centrated waste storage tanks as a worst case scenario for radwaste tank acci-

dents. The licensee assumed that the entire 37,850 L (10,000 gal) volume of ,

the two tanks would flow directly into the discharge canal. The licensee then calculated the concentrations in the canal for Cs-137, Cs-134, Co-60 and Sr-90.

In all cases, the licensee determined that the concentrations in the discharge l

canal were more than an order of magnitude less than the limits given in l

10 CFR 20, Appendix B, Table II. The staff agrees with the licensee's determination.

l Humboldt Bay Unit 3 DES 3-12

The staff also made an independent analysis of the tank spill to estimate popu-lation dose. The staff assumed that the entire contents of the tanks entered Humboldt Bay and remained there for 1 year. This is a very conservative assump-tion because the tidal exchange with the bay is about 44% per tidal cycle. The buildup of the various radionuclides in both finfish and shellfish was estimated, and the commercial fish catch data for Humboldt Bay and Northern California were used to estimate the amount of fish consumed. On the basis of these calcula-tions, using the methods in RG 1.109, the staff estimated that the annual pcpu-lation-integrated total body dose resulting from a tank spill into the discharge canal would be less than 0.1 person rem (Schuyler, July 1984, and RG 1.109).

Thus an average individual consuming finfish and/or shellfish harvested from Humboldt Bay after an accident in which the contents of the two radwaste storage tanks were discharged into the bay would receive, from this food source, much less than the average annual background radiation dose received by individ-uals in the United States from all sources. Again, doses resulting from water recreational activities would be negligible compared with those resulting from seafood consumption.

J Humboldt Bay Unit 3 DES 3-13

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SUMMARY

OF DECOMMISSIONING ALTERNATIVES

'The proposed decommissioning alternative, SAFSTOR, and other-possible alterna-

j. tives are discussed in Section 1.3. Table 4.1 provides summary compari- *

sons of the alternatives.

V L Facility restart is not a viable alternative ^because the licensee has concluded l tha the restart of Humboldt Bay Unit 3 is economically unattractive. The li-cei- e concluded this because the costs of meeting NRC seismic requirements and

aodifications imposed since the accident at Three Mile Island Unit 2-(TMI-2).

[ would be high and the total scope of'such modifications-is uncertain.

l 6 i- The DECON decommissioning alternative is not feasible because there is no i effective location for the spent fuel other than onsite storage in the spent-

~

i fuel pool '(see Section 1.3.3). In addition, DECON would result in greater j occupational radiation exposures to workers and more radioactive waste than 1 other alternatives. 4 Again, with spent fuel stored on the site, the ENTOMB alternative is not prac-i ti cal . Continued surveillance and security would be needed for spent fuel i storage under this alternative. There also would be'the potential of the-en-i tombment structure failing as a result of seismic events'. In addition, there j would be greater difficulty in monitoring during the entombment period and-in the future removal of residual radioactivity.. .

Although the SAFSTOR decommissioning alternative may have a higher dollar cost

j. than other alternatives, the occupational radiation exposures would be the i ,

i lowest. Also, the volume of solid radioactive waste for transport and disposal is likely to be lower because dismantling would take place after a 39-year. radio-l' active decay period (since shutdown in July 1976).

SAFSTOR also is the preferred action because of the need to maintain onsite-l storage of spent fuel until a Federal repository is available. On August 31,  ;

1 1984, the Commission issued the " Waste Confidence Decision"-(49 FR.'34658) and l amended 10 CFR 51.23 and 51.30. In this rule, the Commission folind that no-significant envirom.cntal impacts will result from the storage of spent fuel .

j s

in reactor facility storage pools for at least 30 years 1beyond the expiration l of nuclear reactor operating licenses. > This conclusion by the Commission sup--

ports the proposed SAFSTOR option at Humboldt-Bay Unit 3.

l The Nuclear Waste Policy Act of 1982 established a framework for the disposal :i I

of high level waste, including spent nuclear fuel. The'Act stated that the  !

i primary responsibility for providing interim spent fuel storage rests with the .j licensee. Fuel storage must continue at a pe'rmanently shutdown reactor facility  :

such as ~Humboldt Bay Unit'3 until a Federal repository is 'available, unless

]

' the licensee has another facility that is suitable. :The SAFSTOR option is the - ')

only option that is compatible with.long-term onsite storage of spent fuel at.

i-I ~i l ~Humboldt Bay Unit 3 DES- -

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j- :Humboldt Bay Unit 3. In sumary, the benefits of the SAFSTOR option and the

' unavailability of a Federal repository for spent-fuel outweighs potentially I

higher costs.

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p Table 4.1 Comparison of Humboldt Bay Unit 3 decommissioning alternatives

?r Potential release Other potential S Alternative Potential advantages Potential disadvantages of radioactivity effects

.DECON If fuel is shipped off- About twice the occupa- Moderate release poten- Requires transfer of-p (immediate site, lowest cost of any tional dose of the other tial during dismantling; more curies and vol-

- dismantle- alternative; fastest re- action alternatives; eliminates potential re- ume of radioactive

[ ment) lease of land for unre- largest amount of radio- lease of radioactivity waste to disposal stricted use; immediate active waste to be trans- after dismantling is sites; and more land E

" removal o.' radioactivity ported; not compatible complete. for burial of radio-from the site. with Waste Policy Act of active waste. Truck 1982 with respect to on- traffic increase off site fuel storage. the site.

1 ENTOMB Intermediate occupational Potential for failure of Low release potential Site is not available radiation dose; reduced entombment structure dt.e during preparation for for other use for very amount.of solid radio- to seismic events; not entombment, moderate long time (unless a active waste to be trans- compatible with Waste potential for release structures are opened.

c!> ported. Policy Act of 1982 with during entombment. and residual radio- )

respect to onsite fuel activity removed).

storage. No offsite non- i radiological impacts.

l 1

SAFSTOR; Lowest occupational ra- Requires survei . . .r.ce for Very low potential for Site is unavailable '

deferred diation dose of any 30 more years. release during safe for other uses for DECON action alternative; con - storage and deferred 30 more years.

(preferred sistent with Waste Policy dismantling because of No offsite non-alternative) Act of 1982 with respect easy access for monitor- radiological impacts to onsite fuel storage; ing and maintenance dur- during SAFSTOR period.

less commitment of land ing storage and reduced Reduced offsite truck area to radioactive waste radioactivity during traffic for waste disposal. dismantling. disposal during final DECON.

2 Table 4.1 (Continued)

E ll Potential release Other potential g

& Alternative Potential advantages Potential disadvantages of radioactivity effects No action; Delays'the need for de- Uncertainty about protec- Moderate potential for Site is unavailable g: continue commissioning plans and tion of health and safety release of radioactive for other uses for y surveillance actions; initial costs and environment; continued material from deterio- an indefinite period.

, reduced. high security and surveil- rating equipment and .No offsite non-lance costs; lack of tanks that contain low radiological impacts.

o level radioactive wastes.

g planning may result in higher final cost for re-moval of residual radio-activity.

.t

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t 5 CONCLUSIONS The staff issued a Draft Generic Environmental Impact Statement (GEIS) (NUREG-0586) in support of proposed rulemaking for the decommissioning of nuclear facilities.

The staff concludes in the GEIS that the technical basis exists for decommission-ing plants in a safe, efficient, and timely manner.

In the case of Humboldt Bay Unit 3, storing the spent fuel assemblies at Humboldt Bay is the sole viable alternative for spent fuel storage. 10 CFR Part 51.23(a) states that the Comission has made a generic determination that for at least 30 years.beyond the expiration of reactor operating licenses, no significaat environmental impacts will result from the storage of spent fuel in reactor facility storage pools. Because spent fuel is to be stored in the pool until a DOE repository is ready to receive it, SAFSTOR is the preferred and acceptable decomissioning mode for Humboldt Bay Unit 3.

On the basis of its review of the plant's health physics organization, equipment, and procedures, the staff concludes that the licensee has established a radiation protection program that will maintain radiation exposures within the applicable limits of 10 CFR 20 and will maintain exposures ALARA in accordance with ,

NUREG-0800 and RG 8.8. The staff concludes that a fuel handling accident resulting in damage to two spent fuel assemblies will result in atmospheric radionuclide releases that are very small and well below the EPA PAG levels at which protective actions would be warranted.

The staff similarly concludes that damage to all the stored spent fuel assemblies resulting from a non-mechanistic heavy load drop would result in atmospheric radionuclide releases that also are well below the PAG levels.

The staff also concludes that there is a negligibly small likelihood that seismic loads or other mechanical loads would generate criticality among the spent fuel assemblies stored in the pool. )

i The staff has determined that the upper limits of potential lung, liver, and bone doses resulting from an instantaneous expulsion to the atmosphere of the entire water /radionuclide content of the spent fuel pool are very small fractions of the PAG levels.

The staff also has determined that a rupture of the spent fuel pool or the liquid radwaste tanks would result in a total body dose to an average individual via the seafood chain that would be less than the dose from natural background levels. Doses resulting from water recreational activities in Humboldt Bay would be negligible.

As a result of its analysis and review of potential environmental, technical, and societal impacts, the staff has determined that Humboldt Bay Unit 3 can be placed in SAFSTOR for a 30-year period with minimal eavironmental impact.

Humboldt Bay Unit 3 DES 5-1

6 REFERENCES International Comission on Radiological Protection (ICRP), "Recomendations of l the International Comission on Radiological Protection," ICRP Publication 26, January 1972.

l National Academy of Sciences, Advisory Committee on the Biological Effects of Ionizing Radiation, "The Effects on Populations of Exposure to Low Levels of Ionizing Radiation" (BEIR I), 1972.

-- , "The Effects on Populations of Exposure to Low Levels of Ionizing Radiation" (BEIR III), 1980.

National Council on Radiation Protection and Measurements (NCRP), " Review of the Current State of Radiation Protection Philosophy," NCRP Report No. 43, January 1975.

Nuclear Waste Policy Act of 1982 (Public Law 97-425, January 7,1983).

Pacific Gas and Electric Company (PG&E), " Final Hazards Sumary Report - Humboldt Bay Nuclear Power Plant Unit No. 3," September 1, 1961.

Schuyler, J. 0., PG&E, letter to H. R. Denton, NRC, HBL-84-027, July 30,1984.

Shiffer, J. D., PG&E, letter to J. A. Zwolinski, NRC, " Responses to NRC staff questions of January 23, 1985," February 28, 1985.

-- , letter to J. A. Zwolinski, NRC, " Responses to NRC staff questions of January 23, 1985 and February 14, 1985," April 3, 1985.

-- , letter to J. A. Zwolinski, NRC, "Humboldt Bay Power Plant Unit 3 Criticality Analysis for SAFSTOR Decomissioning," July 30, 1985.

-- , letter to J. A. Zwolinski, NRC, "Humboldt SAFSTOR Decomissioning-Document Transmittal" October 7, 1985.

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR),

" Ionizing Radiation: Sources and Biological Effects," 1982.

U.S. Environmental Protection Agency, " Manual of Protective Action Guides and Protective Actions for Nuclear Incidents," EPA-520/-75-001, September 1975.

U.S. Nuclear Regulatory Commission, " Amendment of License No. DPR-7 to Possess-But-Not-0perate Status," letter 6505-07-023, July 16, 1985.

-- , Regulatory Guide (RG) 1.109, "Calculati,on of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I," Revision 1, October 1977.

-- , RG 4.2, " Preparation of Environmental Reports for Nuclear Power Stations,"

Revision 2, July 1976.

Humboldt Bay Unit 3 DES 6-1

-- , RG 8.8, "Information Relevant to Ensuring that Occupational Radiation Exposures at Nuclear Power Stations Will Be as Low as Is Reasonably Achievable,"

Pevisic 3, June 1978. l

-- , NUREG-0554, " Single Failure Proof Cranes for Nuclear Power Plants," May 1979.

-- , NUREG-0555, " Environmental Standard Review Plans," May 1979.

-- , NUREG-0575, " Final Generic Environmental Impact Statement on Handling and

- Storage of Spent Light Water Power Reactor Fuel," August 1979.

-- , NUREG-0586, " Draft Generic Environmental Impact Statement on Decommissioning of Nuclear Facilities," January 1981.

-- , NUREG-0612, " Control of Heavy Loads at Nuclear Power Plants," July 1980.

-- , NUREG-0800, " Standard Review Plan for the Safety Review of Light-Water-Cooled Reactors," July 1981.

l

-- , NUREG/CR-0672, " Technology, Safety and Costs of Decommissioning a Reference-Boiling Water Reactor Power System," June 1980.

-- , " Waste Confidence Decision," 49 FR 34658-34688, August 31, 1984.

Zwolinski, J.'A., NRC, letter to J. O. Shiffer, PG&E, December 18, 1984.

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Humboldt Bay Unit 3 DES 6-2

I 7 CONTRIBUTORS l -This Draft Environmental Statement is a product of the NRC staff. The principal l contributors to this report are ,

j Staff Title Organization  !

l Louis Bykoski Regional Environmental Economist Siting Analysis Branch-Peter Erickson Project Manager Standardfration & Special Projects Directorate Germain LaRoche Environmental Scientist Uranium Fuel Licensing Branch Charles Nichols Senior Nuclear Engineer Plant, Electrical, Instrumentation & Control Systems Branch 4

Robert Samworth Senior Reactor Systems Engineer Facility Operations Branch Jerry Swift Reliability & Risk Analyst Reliability & Risk Assessment Branch Rex Wescott Hydraulic Engineer Engineering Branch Frank Witt Chemical Engineer Plant Systems Branch Millard Wohl Reactor Engineer Technical Specification Coordination Branch Walter Brooks Nuclear Engineer Reactor Systems Branch i

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Humboldt Bay Unit 3 DES 7-1

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8 LIST OF AGENCIES AND ORGANIZATIONS TO WHOM COPIES OF THE DRAFT ENVIRONMENTAL STATEMENT WERE SENT Advisory Council on Historic Preservation Attorney General, State of California California Department of Conservation California Energy Facilities Siting Commission California Energy Resources Conservation and Development Commission California Office of Intergovernmental Management California Public Utilities Commission California State Clearinghouse California State Department of Health Services Federal Emergency Management Administration Federal Energy Regulatory Commission Forest Service Field Office - California Region Humboldt County Board of Supervisors i The Conservation Foundation i U.S. Army Corps of Engineers, San Francisco District U.S. Department of Agriculture i

a. Natural Resources and Economic Division

b. Rural Electrification Administration

c. Soil Conservation Service, State Office

U.S. Department of Connerce U.S. Department of Health and Human Services U.S. Department of Housing and Urban Development, San Francisco Region U.S. Department of the Interior, Office of Environmental Project Review U.S. Department of Transportation, San Francisco Region U.S. Environmental Protection Agency Office of Federal Activities Humboldt Bay Unit 3 DES 8-1

n,.p,e a m a '--G n-D'"4" 0 n a4 2 Ak' 4&>r4Au a, n-es "- 4 a wo; t

I 9 RESERVED FOR STAFF RESPONSES TO COMMENTS ON THE DRAFT ENVIRONMENTAL l STATEMENT i,

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l APPENDIX A C'lLTURAL RESOURCES: LETTER FROM -

STATE HISTORIC PRESERVATION OFFICER 4

1 Humboldt Bay Unit 3 DES Appendix A a

1 graft of CAUPoeMIA-flet assoveCES motNCY otopct ogUEMEJ1AN, CSFFM3F OFFICE OF HISTORIC PRESERVATION g

IWANTMENT OF PARKS AND RfCREATION peer opnet aox asso sacauemo, ceonema ,ssu l 49163 6 8006 REPLYTO; NRC841127A '

April 17, 1985 i Mr. Tranklin J. Burney Pacific Gas and Electric Company 77 Beale Street San Francisco, CA 94106 L

Dear Mr. ,

Burney:

RI: Humboldt Bay Unit 3 Decommissioning Thank you for requesting our comments on the above cited project. We con:ur in your determination that this undertaking does not involve National Register or eligible properties.

If my staff can be of any further assistance, please contact Dwight Dutschke at (916) 322-9624.

Sincerely, lf' Kathryn Gua tieri State Historic Preservation Officer Humboldt Bay Unit 3 DES 1 Appendix A

T.

APPENDIX B EXAMPLES OF SITE-SPECIFIC DOSE ASSESSMENT CALCULATIONS l

l i

l Humboldt Bay Unit 3 DES -Appendix 8

APPENDIX B EXAMPLES OF SITE-SPECIFIC DOSE ASSESSMENT CALCULATIONS

1. Calculational Approach As mentioned in the main body of this report, the quantities of radioactive material that may be released annually from the Humboldt Bay Power Plant are estimated on the basis of the description of the design and operation of the radwaste systems as contained in the licensee's Environmental Report and SAFSTOR Decommissioning Plan (Schuyler, July 1984) and periodic reports on radioactive

, effluent releases and waste disposal covering the years 1977 through 1983 (when Humboldt Bay Unit 3 was shut down). On the average, actual releases are expected to be less_than those given in these documents because of the radioactive decay that will take place over the 30-year SAFSTOR period. For calculational conser-

. vatism, a minimal amount of selected radionuclides (4 microcuries per year) was included in the annual releases, although in recent years they have not been reported and in most cases are not expected. During the 30-year SAFSTOR period, most of the released radionuclide quantities are expected to originate with spent i

fuel storage operations. However, lesser quantities of radionuclides that may be leached from contaminated soil on the site have been included in the calcula-i tions. These estimated values of effluent releases during SAFSTOR, along with

the licensee's site and environmental data in the ER and in subsequent answers

to NRC staff questions, have been used in the staff's calculation of radiation t

doses and dose commitments.

RG 1.109, Revision 1 discusses in detail the models and considerations for i environmental pathways that lead to estimates (1) of radiation doses and dose i commitments to individual members of the public near the plant and (2) of cumu-j lative doses and dose commitments to the entire population within an 80-km (50-mile) radius of the plant as a result of plant operations. The calculations

~

performed by the staff for the releases to the atmosphere and hydrosphere provide I

total integrated dose commitments to the entire population within 80-km of this facility based on the projected population distribution in the year 2000. The dose commitments represent the total dose that would be received over a 50-year period, fellowing the intake of radioactivity for 1 year under the conditions existing 30 yearl after the beginning of SAFSTOR operation (that is, the end-point of SAFSTOR operation). For younger persons, changes in organ mass and metabolic parameters with age after the initial intake of radioactivity are accounted for. i 2

2. Dose Commitments from Radioactive Effluent Releases The NRC staff's estimates of the expected gaseous and particulate releases (listed in Table 3.2 of the main body of this report) and site meteorological considerations were used to estimate radiation doses and dose commitments for airborne effluents. Individual receptor location and pathway location's consid-ered for the maximally exposed individual in these calculations are given in i Table B.1.

1 Humboldt Bay Unit 3 DES 1 Appendix B

__ _. - _ _ - ~ - . . - _ _.

l Two years of onsite meteorological data (January 1976 to December 1977) were used in the calculation of effluent concentrations given in Table B.1. The data were comprised of wind speed and wind direction measured at 76 meters, and vertical temperature difference between 7.6 and 76.2 meters. These data were combined in a joint frequency distribution, used in a straight line gaussian plume model corrected for terrain heights and effluent recirculation using standard correction factors (NUREG/CR-2919). All releases were assumed to be continuous and out of the 76-meter plant stack.

The NRC staff estimates of the expected liquid releases (listed in Table 3.1) and the site hydrological considerations (summarized in Table 8.2) were used to estimate radiation doses and dose commitments from liquid releases. Leaching of contaminated soil on site was included in the estimates.

(a) Radiation Dose Commitments to Individual Members of the Public Calculations are made for a hypothetical individual member of the public (the maximally exposed individual) who would be expected to receive the highest radiation dose from all pathways that contribute. This method tends to over-estimate the doses because assumptions are made that would be difficult for a real individual to fulfill.

The estimated dose comitments to the individual who is subject to maximum exposure at selected offsite locations from airborne releases of radioiodine and particulates, and waterborne releases are listed in Tables B.3 and B.4.

The maximum annual total body and skin dose to a hypothetical individual and the maximum beta and gamma air dose at the site boundary are in Tables B.3 and B.4.

The maximally exposed individual is assumed to consume well above average quantities of the potentially affected foods and to spend more time at poten-tially affected locations than the average person, as indicated in Tables E-4 and E-5 of Revision 1 of RG 1.109.

1 (b) Cumulative Dose Commitments to the General Population l Annual radiation dose commitments from airborne and waterborne radioactive releases from the Humboldt Bay Power Plant Unit 3 are estimated in Table B.4 for all members of the general public within 80-km (50-miles) of the station in the year 2000. For perspective, annual background radiation doses are given in the table.

3. References Schuyler, J. 0., PG&E, Letter to Harold R. Denton, NRC, HBL-84-027, July 30,1984.

U.S. Nuclear Regulatory Commission, RG 1.109, " Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I," Revision 1, October 1977.

-- , RG 1.111. " Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light-Water Reactors," Revision 1, 1977.

-- , NUREG/CR-2919, "X0QD0Q: Computer Program for Meteorological Evaluation of Routine Effluent Release at Nuclear Power Plants," May 1985.

Humboldt Bay Unit 3 DES 2 Appendix B

Table B.1 Summary of atmospheric dispersion factors (x/Q) and relative deposition values for maximum site boundary and receptor ~ ~

locations near Humboldt Bay Power Plant Unit 3*

Relative Location ** Source *** X/Q (sec/m8 ) deposition (m.2)

Nearest effluent- Unit 3 control boundary stack 4.42x10 4 6.12x10 7 (0.32 km S)

• The values presented in this table are calculated in accordance with Regulatory Guide 1.111, Rev. 1 " Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light Water Reactors," July 1977.

• • " Nearest" refers to that type of location where the highest radiation dose is expected to occur from all appropriate pathways. Beta and gamma air doses, total body doses, and skin doses from noble gases are determined at the effluent-control boundaries in the sector where the maximum potential value is likely to occur. Dose pathways including inhalation of atmo-

, spheric radioactivity, exposure to deposited radionuclides, and submersion in gaseous radioactivity are evaluated at residences. In this instance, the doses were calculated as if the nearest residence, nearest vegetable garden, nearest milk cow, nearest milk goat, and nearest meat animal were all situated at the site boundary 0.32 km south of the stack.

• • • Source: Unit 3 stack, continuous release. Dispersion conservatively calculated as if the releases were at ground level.

Table B.2 Summary of hydrologic transport and dispersing for liquid releases from Humboldt Bay Power Plant Unit 3*

Transit time Dilution Location (hours) factor Nearest sport-fishing location 0 10 (discharge area)**

Nearest shoreline 0 10

] (shoreline near discharge area)

• See Regulatory Guide 1.113, " Estimating Aquatic Dispersion of Effluents from Accidental and Routine Reactor Releases for the Purpose of Implementing Appendix I," April 1977.

• • Assumed for purposes of an upper limit estimate.

I Humboldt Bay Unit 3 DES 3 Appendix B

Table B.3 -Annual dose commitments to a maximally exposed individual near Humboldt Bay Power Plant Unit 3 Location Pathway Doses (mrem /yr, except as noted)

Noble gases in gaseous effluents Total Gamma air dose Beta air dose body Skin (mrads/yr) (mrads/yr)

N: trest

• site Direct radiation b:undary from plume a a b b (0.32 km S)

Iodine, particulates in gaseous effluents **

Total body Organ N:arest*** site Ground deposition 0.1 ' 0.1 b:undary (0.32 km S) Inhalation a a N:arest residence Ground deposition 0.1 0.1 cnd garden, milk Inhalation a a cow, milk goat, Vegetable consumption 0.1 0.2(C)(bone) cnd meat animal Cow .nilk consumption a 0.1(I)(bone)

(0.32 km S) Goat milk consumption a 0.1(C)(bone) 0.2(I)(liver)

Meat consumption a a Liquid effluents **

Total body Organ N:arest drinking Water ingestion c c water l N:erest fish at Fish consumption a a plant-discharge

) arza Nsarest shore Shoreline recreation a a access near plant-discharge area Lsgend: a = Less than 0.1 mrem / year; b = Less than 0.1 mrad / year; c = Releases into the salty water of Humboldt Bay, which is 'not used for drinking water supplies.

" Nearest = that site boundary location where the highest radiation doses as a result of gaseous effluents have been estimated to occur.

• • Doses = the age group and organ that results in the highest cumulative dose for the location: A= adult, T= teen, C= child, I= infant. Calculations were made for these age groups and for the following organs: gastrointestinal tract, bone, liver, kidney, thyroid, lung, and skin.

• • • Nearest = the location where the highest radiation dose to an individual from all applicable pathways has been estimated.

Humboldt Bay Unit 3 DES 4 Appendix 8

Table B.3 Annual dose commitments to a maximally exposed individual near Humboldt Bay Power Plant Unit 3 Location Pathway Doses (mrem /yr, except as noted)

Noble gases in gaseous effluents Total Gamma air dose Beta air dose body Skin (mrads/yr) (mr ads /yr)

N arest* site Direct radiation boundary from plume a a b b (0.32 km S)

Iodine, particulates in gaseous effluents **

Total body Organ N arest*** site Ground deposition 0.1 0.1 b:undary (0.32 km S) Inhalation a a N:arest residence Ground deposition 0.1 0.1 and garden, milk Inhalation a a cow, milk goat, Vegetable consumption 0.1 0.2(C)(bone) and meat animal Cow milk consumption a 0.1(I)(bone)

(0.32 km S) Goat milk consumption a 0.1(C)(bone) 0.2(I)(liver)

Meat consumption a a Liquid effluents **

Total body Organ N:arest drinking Water ingestion c c water N : rest fish at Fish consumption a a plant-discharge crea N: trest shore Shoreline recreation a a access near plant-discharge area Legend: e = Less than 0.1 mrem / year; b = Less than 0.1 mrad / year; c = Releases into the salty water of Humboldt Bay, which is not used for drinking water supplies.

• Nearest = that site boundary location where the highest radiation doses as a result of gaseous ef fluents have been estimated to occur.

• • Doses = the age group and organ that results in the highest cumulative dose for the location: A= adult, T= teen, C= child, I= infant. Calculations were made for these age groups and for the following organs: gastrointestinal tract, bone, liver, kidney, thyroid, lung, and skin.

• • • Nearest = the location where the highest radiation dose to an individual from all applicable pathways has been estimated.

l Humboldt Bay Unit 3 DES 4 Appendix B

\

w Table B.4 Calculated annual dose commitments to a maximally exposed individual and to thelpop'ulation from SAFSTOR of Humboldt Bay Power Plant Unit 3*

s Source Individual **

Liquid effluents Dose to total body from all pathways a l Dose to any organ from all pathways a l

l Noble-gas effluents (at site boundary)

Gamma dose in air .) b Beta dose in air b Dose to total body of any individual s a

{' Dose to skin of an individual 3~ a 1

Radioiodines and particulates in gaseous effluents ***

Dose to any organ from all pathways 0.4 mrem Population dose within 80 km, person-rems Total body Liver Natural-background radiation. 13,000 -

Liquid effluents 0.4 0.6 Noble-gas effluents c c Radioiodine and particulates 0.1 0.1 Legend: a = Less than 0.1 mrem / year; b = Less than 0.1 mrad / year; c = Less than 0.1 person-rem / year.

• Although Appendix I to 10 CFR 50 does not apply because SAFSTOR conditions are not part of normal reactor operation, the staff notes that the annual doses in this table are much less than the annual dose design objectives of Appendix 1.

• • Numerical values for individual doses were obtained by summing appropriate values in Table B.3. Locations resulting in maximum doses are represented here.

• • • Carbon-14 and tritium have been added to this category.

. Source: " Natural Radiation Exposure in the United States," U.S. Environmental Protection Agency, ORP-SID-72-1, June 1972; using the average background dose for California of 100 mrems/yr and year 2000 projected, population of 130,000.

4 Humboldt Bay Unit 3 DES 5 Appendix B l

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l i-i APPENDIX C RESERVED FOR COPMENTS ON THE DRAFT ENVIRONMENTAL STATEMENT t

L Humboldt Bay Unit 3 DES Appendix C

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BIBLIOGRAPHIC DATA SHEET NUREG-1166 DES 3 TITLE AND SUGTITLE e RtcapitNT ($$ SON Nuest R Draft Environmental Statement for Decommissioning Humboldt Bay Power Plant, Unit No; 3 , o,,,,7, 0,,co ,,,,,o

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h A[0,,1 1986 I 4 AUTHORISI g y ATI REPORT 155UED -

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Division of Pressuriz\ed Water Reactor Licensing-B Office of Nuclear Reactor Regulation '* "' *"*" -I U.S. Nuclear Regulatory'(ommission T Washington, DC 20555 \

\ / 7j 11 SPON50ReNG ORGANIZATRON NAME AND MAILIN^ DORE $$ (1,ec4,ar le code # r t2a TVPt OF REPORT _

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Same as 7 above l ,:. P.R CocOvnRnOs,~, ,

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7 Docket No. 50-133 \s  !'

i. AssTRACT,m ., ,

This Draft Environn.ntal Statement contains the assessment of the environmental _aier, impact associated w. .h decomissioning th'e Humboldt Bay Power Plant Unit 3 -

pursuant to the Nat: al Environmental Polfc of the Cbde of Federal Regulations, Part 51,ylAct of 1969 (NEPA) andPagulatory Title 10 4 tas amended, of the Nuclear -

Conmission regulations. The proposed decommissioning would involve safe -j storage of the facility for about 30 years f after which the residual radioactivity r would be removed so that the facility would be ah y levels of radioactivity acceptable for release of the facility to hnrestricted access. _,

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