ML16340C732

Responds to Re Concerns Over Amount of Radiation & Increase of Tritium Proposed for Release Into Pacific Ocean.Required Design Measures Taken to Process Contaminated Liquid Effluents to Minimize Release

ML16340C732
Person / Time
Site:	Diablo Canyon
Issue date:	07/21/1982
From:	Harold Denton Office of Nuclear Reactor Regulation
To:	Kenneth Jones CALIFORNIA, STATE OF
Shared Package
ML16340C623	List: ML16340C732
References
NUDOCS 8208040532
Download: ML16340C732 (46)

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~O sI sI.*y4 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 QQ QP Mr. Kenneth R. Jones Executive Officer Cal ifornia Regional Water gual ity Control Board - Central Coast Region 1102 A Laurel Lane San Luis Obispo, California.

93401

Dear Mr. Jones:

This is in response to your June 15, 1982 letter which has been referred to me for reply.

I regret any inconvenience caused by the delay in responding to your earlier letters of January 19 and February 18, 1982, which regrettably were not entered into our computer tracking system for such correspondence.

In those letters you raised certain concerns in regard to the Diablo Canyon facility.

Each of these concerns are addressed below.

Concern "We have serious concerns over the amount of radiation and the considerable.

increase in tritium over background levels you propose to allow PG&E to release to the Pacific Ocean."

~Res ense Our evaluation of the liquid radwaste treatment system at the Diablo Canyon Nuclear Power Station, Units 1

and 2, has been provided in Chapter 11 of our Safety Evaluation Report (SER) dated October 16, 1974.

In Supplement No. 6 (July 14, 1977) to the SER, we calculated the releases during normal operation and anticipated operating occurrences to be 0.34 curies/year/unit.

excluding tritium and 710'curies/year/unit for tritium.

These releases were determined based on the operating experience of similar pressurized water reactors with more than 700 reactor years of use with similar radwaste.treatment systems and components.

Based on our evaluation, we concluded that the system satisfied the "as low as is. reasonably achievable" criteria of Appendix I to 10 CFR Part 50 and was capable of meeting the requirements. of 1Q. CFR Parts 50.34a and

%.36a.

In addition, we reviewed the equipment and instrumentation provisions and determined that the system contained adequate control features to assure that concentration levels would be below.the limits of Appendix B to 10.

CFR Part 20, and that releases would be controlled and monitored according to the criteria in GDC 60 and 64 in Appendix A to 10 CFR Part 5G.

The Technical Specifications for Diablo Canyon Station (NUREG-0817, September 1981) contain specifications to assure that these requirements are met.

The largest estimates 8208040532 820721 PDR ADQCK 05000275 P

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Mr. Kenneth R. Jones of dose from liquid effluents, including tritium, released from the station are for a resident of the Diablo Canyon area who makes frequent use of the ocean shore and whose dietary habits include suhstantial amounts of fish and abalone.

The estimates of the total dose to the thyroid of an individual are 0.02 millirem and less than O.Ql millirem to the total body and the other internal organs.

These estimates of dose, based on reasonable dilution factors of the liquid effluent for the ocean and on reasonable deposition rates from the water to the beaches, are less than 0.02K of the dose from the natural radiation background and less than Q.04% of the recomended numerical dose 1 imits.

Since this evaluation was completed, there has been no change to the liquid radwaste system or the method of calculating the amount of radioactive materials in 'liquid re1eases to alter the conclusions reached in the SER.

Concern "We are concerned that you are allowing the volume of the cooling water discharge to justify bypassing treatment levels that would be unacceptable at other nuclear facilities.

Please re-examine your proposed permit.to reduce significantly the radiation releases to the Diablo Cove."

~Res onse As discussed above, all required design measures have been taken to process contaminated liquid effluents within the Diablo Canyon facility to minimize the release of radioactive material to the Diablo Cove.

The practice of diluting the treated contaminated effluents with the ocean water being discharged from the condenser is applicable to the Diablo Canyon facility

.and its use is widespread in.the operation of all nuclear power plants.

All nuclear power plants are required to meet the same Federal Regulations and design objectives of 1Q CFR Part 50, Appendix I.

As. discussed

above, the effects of these releases.

were found to he insignificant.

Concern "Our second main concern is. in regards to the 26,00Q curies per year of radiation that you propose to allow Diablo Canyon to discharge into the atmosphere."

~Res onse In Supplement No.

6 to the SER, we calculated the releases during normal operation and anticipated operational occurrences to be 2,600 curies/year/unit of noble gases, as shown in Table 11.2 on page 11-8.

The 26,000 curie value you refer to is a factor of ten greater than what is expected to be released over a period of a year.

Instantaneous release rates greater than 2,600. curies per year are permitted to allow for anticipated fluctuations in release rates.

We do not expect the annual release rate to exceed 2,6QQ curies per unit per year.

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Mr. Kenneth R. Jones The gaseous radwaste treatment system was. also evaluated as in our response to your first concern above.

No new information is available that would cause us to change our previous conclusions reached in the SER.

Concern "Since there are many days per year of foggy weather at the site, we are concerned that a radioactive rain may develop contaminating water in the vicinity.

Me would appreciate any documentation that you have regarding radioactive isotope soluability in rain and/or fog.

Mhen questioned on this at our hearing, PGSE officials stated that there are no operational restrictions concerning weather conditions imposed by the NRC.

Mhy not?

Is. it necessary to release 26,000 curies of radiation per year?"

~Res ense In Supplement No.

6 to the SER, we have shown that during norJDal operation and anticipated operational occurrences the dose impact to an individual or the population due to releases of radioactive material in gaseous effluents will be a fraction of the requirements of Appendix I to 10 CFR Part 50.

In addition, the concentration of radioactive materials in gaseous effluents into the unrestricted area beyond the site boundary will be below the concentration limits of Appendix B to 10 CFR Part 20, at all times.

Since the limiting conditions for operation are specified within the Technical Specifications (NUREG-0817) in terms of a dose rate at any time, there is no need to address specific operational restrictions due to variable weather conditions.

As stated

above, we do not anticipate an annual average release of 26,000 curies per year.

The solubility of various isotopes can be found in the following reference:

"International Critical Tables of Numerical Data, Physics, Chemistry and Technology", published for the National Research Council by the McGraw-Hill Book Company, Inc.

Concern "Our third concern is that the ocean monitoring program for radiation is not adequate.

Additional monitoring stations are needed, especially in the Pismo Beach area.

Also a broader spectrum of shellfish should be monitored, as should sediment in the area of the discharge."

~Res onse The radiological monitoring program required by Diablo Canyon Technical Specifications provides measurements of radiation and of radioactive materials in those exposure pathways and for those radionuclides, which lead to the highest potential radiation exposures of individuals resulting from the station operation.

This monitoring program thereby supplements the radiological effluent monitoring program by verifying that the measurable concentrations of

Mr. Kenneth R. Jones 4-radioactive materials and levels of radiation are not higher than expected on the basis of the effluent measurements and modeling of the environmental exposure pathways.

The initially specified monitoring program will be effective for at least the first three years of comnercial operation.,

Following this

period, program changes may be initiated based on operational experience.

Regarding sampling at the Pismo State Park beach area, this. beach is approximately 15 miles from the site.

Experience with ocean dilution currents indicates that radionuclides that may be released from the Diablo Canyon Nuclear Station will be undetectable and within natural background levels at the heach area.

All the models that. we have used to estimate ocean concentration of radioactive effluents indicate that monitoring at this distance from the station would result. in no statistically useful results.

Fish and aquatic invertebrates are required to be sampled by Table 3.12-1 of the Technical Specifications at least-once per 184 days.

Since these organisms are known to bioaccumulate radioactive materials, the bi-yearly sampling period is considered appropriate.

Because of the significant ocean dilution occurring near the plant, no radioactivity would he expected to be found in fish or shellfish resulting from the plant.

Sampling of bottom strata in the area, of the discharge is not required by the Technical Specifications

because, the, bottom is not sedimentary but rock and base gravel.

Concern "Another serious concern is the potential for contamination of the Pacific Ocean in the event of an accident or uncontemplated release of radioactivity through a liquid pathway.

The design and construction errors discovered at the plant may substantially increase, the chances for such an event; Therefore, it is imperative that your Comnission ensure prior to operation that the plant, as actually constructed, is safe in this regard, and that emergency plans include consideration of liquid releases.

Independent audits are a vital link in such assurance.

We would like to request that a liquid pathway study he completed for Diablo Canyon, including an evaluation of the consequences of a Class 9 accident.

Design and construction review of Diablo Canyon must include specific evaluation of piping, pumps, valves, waste storage

areas, turbine bui.lding, storage

areas, etc."

~Res onse The design and construction errors you refer to are, I presume, those errors associated with the seismic design of th'e Diablo Canyon Plants.

As you may know, there is an on-going Independent Design Verification Program and the principal objective is to restore the plant such that its construction satisfies the approved seismic design criteria.

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1 Mr. Kenneth R. Jones Nth respect to your request to conduct a liquid pathway study and an evaluation of the consequences of a Class, 9 accident, these matters were previously considered as a result of a petition dated October 24. 1979, filed by. W. Andrew Baldwin on behalf of the Friends of the Earth, San Francisco, California.

A copy of the Directors Decision fs attached for your fnformatfon.

Under current Commission regulation, Diablo Canyon would be, excluded from being reviewed for Class 9 consequences because ft falls fn a category of plants for which the Final Envfronmental Statement has already been issued.

I trust that the above fnformatfon has been responsive to your concerns.

Sfncemly,-

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Mr. Kenneth R. Jones Sampling of bottom strata fn the area of the discharge fs not required by the Technical Specifications because the bottom is not sedimentary but rock and base gravel.

Concern Another serfms concern fs the potential for contamination of the Pacific Ocean in the event of an accident or uncontemplated release of radioactivity through a li-quid pathway.

The design and construction errors df scovered at the plant may sub-stantially increase the chances: for such an event.

Therefore, ft fs imperative that your Commission ensure prior to operation that the plant, as actually con-structed, is safe fn this. regard, and that eaergency plans include consideration of liquid releases.

Independent audi ts are-a vital link fn such assurance.

Me would like to request: that a liquid pathway stu4 be completed for Diablo Canyon, including an evaluation-of the consequenses of a.Glass 9 accident..

Design and construction review of Diablo Canyon must include specific evaluation of piping, pumps, valves, waste-storage

areas, turbine building, storage

areas, etc.

~Res onse The design and construction errors you refer to are, I presume, those errors associated with the seismic design of the Diablo canyon Plants.

As you may know, there. fs an on-going Independent Design Yerfffcatfon Program and the principal ob-.

jective fs to restore the. plant'uch that fts construction satisfies the approved seismic design criteria.

Mfth respect to your request to conduct. a liquid pathway study and an evaluation of the consequences of a Class 9 accident, these matters were previously consfdered as a result of a-, petition dated October 24, 1979, filed by W. Andrew Baldwin on behalf of the Friends of the Earth, San Francisco, California.

The Ccmmfssfon concluded that the Diablo Canyon Plant did not fit fn a category of nuclear plants with special circumstances that would warrant more extensive consideration of Class 9 accidents.

These special circumstances fall into three categories:

(1) high population density around the proposed site; i.e.

above the trip points in the Standard Review Plan NUREG-0800 (formerly issued as NUREG-75/087) and Regulatory Guide, 4.7, General Site Suitability for Nuclear Power Stations (November 1974); (2) a novel reactor design (a type of power reactor other than a light water reactor); or (3) a combination of a unique design and a unique siting mode.

The enclosed information provides the bases for the above cited Commission's conc lusi on.

I trust that the above information has been responsive to your -concerns.

Sfneer ely, Harold R. Denton, Director Office of Nuclear Reactor Pegulation DL"

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Cite as 11 NRC 91 9 (1 980)

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION Harold R. Denton, Director ln the Matters of ARIZONA PUBLIC SERVICE COMPANY (Palo Verde Nuclear Generating Station, Units 1, 2, and 3)

Docket No. 50-528 CP 50-529 CP 50-530 CP PACIFIC GAS AND ELE~IC COMPANY (Diablo Canyon Nuclear Power Plant, Unlts1-and 2)

Docket No. 50-275'P 5M23 CP SACRAMENTO MUNICIPAL UTILITY DISTRICT (Rancho, Seco. Nuclear Generating Station, Unit 1)

Docket No. 50412 OL June 18, 1980 The Director of Nuclear Reactor Regulation denies a request under 10 CFR 2.206 that the Commission prepare supplemental environmental impact statements to consider the impact of "Class 9" accidents at three power reactor sites.

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NEPh: SEVERE ACCIDENT CONSIDERATIONS RULES OF PRACTICE: REOPENING OF PROCEEDINGS As provided in the Commission's June 1980 "Statement of Interim Policy," the StidI'ill not take action to reopen past NEPA reviews in response to a petition under 10 CFR 2206 in the absence ofsome "special circumstances."

RULES OF PRACTICE: SHOW CAUSE PROCEEDING Where an issue is pending before one of the Commission's adjudicatory

panels, the StaA will not take action under 10 CFR 2206 to institute another proceeding to consider the same issue.

NRC: ENVIRONMENTALRESPONSIBILITIES The Commission is empowered to revise its past policies in an evolutionary process as it gains experience in the application of the laws which, it is charged to administer. A change in policy to allow broader consideration of accidents in future NEPA reviews does not invalidate the findings in past reviews, particularly in view ofjudicial approval of th>>

Commission's past practices.

DIRECTOR'S DECISION UNDER 10 CFR 2206 By petition dated October 24, 1979, W. Andrew Baldwin on behalf ofthe Friends of the Earth (FOE), San Francisco, California, requested that the Director of Nuclear Reactor Regulation take action pursuant to 10 CFR 2206 to require preparation of supplemental environmental impact state-ments on Class 9 accidents at the Diablo Canyon, Palo Verde, and Rancho Seco nuclear plants. Notice of receipt of the FOE's petition was published in the Federal Register, 44 FR 70241 (December 6, 1979). Counsel for the Sacramento Municipal UtilityDistrict (SMUD); the licensee ofthe Rancho Seco Nuclear Generating Station, submitted on December 21,

1979, a

response opposing the FOE's petition. Arizona Public Service Company responded to the petition on February 27, 1980.

The petition requests relief with respect to power reactors under various stages of construction or operation licensed to three primary licensees at three diA'creat sites. The Arizona Public Services Company holds construc-tion permits authorizing construction ofthe Palo Verde Nuclear Generating Station, Units I, 2, and 3, located at the Winterburg site in Arizona. The Pacific Gas and Electric Company is constructing the Diablo Canyon

Nuclear Power Plant, Units I and 2, at its site in California, and has applied for operating licenses for those two units. The Sacramento Municipal Utility District is authorized by the Commission to operate the Rancho Seco Nuclear Generating Station, Unit 1, also located in California The FOE asks that the Commission prepare supplemental environmental impact statements on each ofthese facilities for the followingreasons:

1.

The environmental impact statements suntmarily discuss consider-ation of Class 9 accidents, based on early estimates ofreactor accidents probabilities and on the Reactor Safety Study, WASH-1400, which has since been repudiated by the Commission; and 2.

The accident at Three Mile Island, which the NRC concedes constituted a Class 9 accident, emphasized the need to evaluate the possible impact of a serious (Class 9) accident and to prepare to meet the possible consequences.

For the reasons stated in this decision, the FOE's petition is denied.

L.

COMMISSION POLICY ON ACCIDENT CONSIDERA'HONS The term "Class 9 accident" was employed in a Commission ruiemaking which had been proposed in December 1971:

"Consideration of Accidents in Implementation of the National Environmental Policy Act of 1969," 36 FR 22851 (1971). The proposed rulemaking would have added an Annex to Appendix D of 10 CFR Part 50 to set forth the manner in which various categories of accidents should be taken into account in the environmental review for a nuclear power plant. Since the FOE's petition was-filed, the Commission has, withdrawn the proposed Annex and has provided in its place new interim guidance for the treatment ofaccident risk considerations in NEPA reviews.

See "Nuclear Power Plant Accident Considerations under the National Environmental Policy Act of 1969," 45 FR 40101 (June 13, 1980). This decision has been made in light of the Commission's new interim policy. It is useful, however, to biieflyreview the now withdrawn Annex and other events leading to the Commission's new interim policy.

In the proposed Annex, the Commission divided a theoretical spectrum ofaccidents into classes ranging in severity from "trivial"(Chiss I) to "very serious" (Class 9). Each class of accidents, except Gasses I and 9, was required to be analyzed in evnironmental reports and statements. Accord-ing to the Annex, Class 1 accidents need not be considered because oftheir trivial consequences.

Accidents within Clams 2 through 8 which were "found to have significant adverse environmental eII'ects shall be evaluated as to probability, or frequency of occurrence, to permit estimates to be.

made of environmental risk or cost arising from accidents of the given

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class."

36 FR-22852 (1971). With regard to "Chss 9" accidents, the proposed Annex stated:

The occurcnccs.in Class 9 involve sequences of'ostuhLtod successive failure morc severe than those postulated for the design basis for protective systems and engineered safety features. Their consequences could be severe. However, the probability of their occurrence is so smaU that their environmental risk is extremely low. Defense in depth (multiple physical harness), quality assurance for

design, manufacture, and operation, continued surveillance and

testing, and conservative design are all applied to provide and maintain the required high dc of assurance that potential accidents in this dass sre, and will remain, surficiently remote in probability that the environmental risk is extremely low." 36 FR 22862 (1971).

Accordingly, the Annex did not require discussion of Class 9 accidents in environmental reports and statements.

Although thc Annex was never formally adopted by the Commission, the Commission noted upon publication that the Annex would be useful as "interim guidance" until the Commission took further action on the Annex.

36 FR 22851 (1971). Upon promulgation of 10 CFR Part 51 in 1974, the Commission stated that the adoption ofPart 51 did not affect thc proposed Annex, which was "still under consideration by the Commission." 39 FR 26279 (1974). The staff consistently applied the proposed Annex from 1971 to 1979 as not requiring the consideration of Class 9 accidents in its

- environmental statements.

Reliance on'he Annex has been upheld by decisions of the Commission's adjudicatory panels and by federal courts.'n September

1979, the Commission announced in Onshore Power Systems (Floating Nuclear Power Plants), CL1-79-9, 10 NRC 257 (1979),

that it intended to complete the rulcmaking begun by thc Annex and to re-examine the Commission's policy regarding accident considerations.s The Commission rcqucstcd additionally that the staff:

"1.

Provide us.<<ith its recommendations on how the interim guidance of the Annex might bc modified, on an interim basis and until the rulc making on this subject is completed, to reflec development since 1971, and to accord more fuDy

<<ith current staffpolicy in this area; and.,

'Sar caser sita/ fu Ofihonr Pceser S)oscnss (FkNsing NuoIear po<<a ptsnss), CLI-79-9, 10 NRC 257, 259 nn; 5 and 6 (1979) usaf hLh~9, 8 NRC 194, 210 n. 52 (1978).

stu Ofshore P~ Ssssssus the Comusissiou desaminod that considssation of a Qsss 9

aocidms in the cuvinmmenssl revic<< for flosung nudcar po<<sr plaass <<ss sppsoprisss.

10 NRC at 26061. The Commision did aos use she proceeding so sesotvo she geussic usus of

'msidsssuon of Ctsss 9 aocidcnss at tsud-based

reactors, bus noted shss "lstuoh ~ gsussio aaion is suosu property aad sQ'ectivety dono through rutcmakmg procaxhugs hs~

mscssssod pessons may psrticipase." ld at 262. Sos aho Pic Sonics Grammy ofO~

(Itlsck Fox Station, Uuiss 1 and 2), CUP&4 Docket Nos. 50-556 and 50 557, as 434 - V35.

(Mssch 21, l980).

2.

Ia the interim, pending completion ofthe rule~ oa this subject, brin our attention, any individual cases in which it bchcvcs the caviroanseataI consequences of Class 9 accidents should be considered."

10 NRC 26243. Scc also Public Scrvicc'onyony ofOkIohomo, supra note 2, at M.

In response to the Commission's first request, the staff sent to the Commission recommendations on accident considerations under NEPA in SECY-80-131, dated March ll, 1980. On May 16, 1980, the Commission issued a statement of interim policy in which it withdrew the proposed Annex and suspended the rulemaking that began in 1971 with the publication of the proposed Annex. "Nuclear Power Plant Accident Considerations under the National Environmental Policy Act of 1969," 45 FR 40101 (June 13, 1980). The Commission also provided guidance on accident considerations in on-going NEPA reviews in licensing proceedings

~here a Final Environmental Statement has not yet been issued. Under the Commission's new guidance, environmental impact statements for on-going and future NEPA reviews willgive consideration to a broader spectrum of accidents including severe accidents that may have been designated "Class 9" under the Annex. For the consideration of environmental risks, or impacts, attributable to accidents at a facility, the Commission gave the followingguidance:

"In the analysis aad discussioa ofsuch risks, approximately equal attcatioa shall be given to the probability of occurrence of rcleascs aad to the probability of ocnsrrcace ofthe daviroamcntal consequences ofthose releases....

"Events or accident sequences that lead to releases shall include but aot be limited to those that can be expected to occur. In-plant accident sequences that can lead to a spectrum of releases shall be discussed aad shall iaclucfc sequences that can result in inadequate cooling ofreactor fuel aad to melting ofthc reactor core." 45 FR at 40103.

With rcspcct to plants for which Final Environmental Statements have been issued, the Commission stated in its new interim policy that:

"Itis expected that these revised treatments wiIIlead to conclusions regardiau thc caviroameatal risks of accidents similar to those that would be reached Sy a contiauatioa ofcurrent practices, particularly for cases involving special circum-stances where Class 9 risks have been considered by the staK... lhus, this change ia policy is not to be construed as any lack ofconfidence in conclusions restardiag the environmental risks of accidents expressed in any previously iss Statc-

meats, aor, absent a showing of similar special cirnunstaaccs, as a basis for opening. reopening or cxpaadiag any previous or oa-going proceeding.s commissioners Gillnsky and Bradford disagree with the iuclusiou of the proccdiatt.two sentences. 'Ikey fee} that they are absolutely inconsistent with an evenhanded reappraisal of the former, erroneous position oa Ctass 9 accidents. 45 Fed. Rcg. at 40103.

i "However, it is also the iatcat of the Commission that thc staff take steps to identify additional cases that might warrant carly consideration of either additional features or other actions to prevent or to mitigate thc consequences of serious accidents.

Cam for such consideration are those for which a Final Environmental Statement has already been issued at thc Construction Permit stage but for which thc Operating License review stage has not yct reached. In carryiag out this directive, the staff should consider relevant site features, iacludiag popuhtioa density, associated with accident risk ia comparison to such features at presently operating phnts. StalT should also consider the likehhood that substantive changes in plant design features which may compensate further for adverse site features may be more easily incorporated in plants when construction has aot yet progressed very far.

Thc staff has reviewed information concerning the Diablo Canyon, Palo Verde and Rancho Scco plants to determine whether "special circum-stances" exist which would warrant "opening, reopening, or expanding any previous or on-going proceeding" concerning these facilities.

II.

STAFPS REVIEW FOR SPECIAL CIRCUMSTANCES As the Comntission noted in its new statement ofinterim policy, the staff has identified in the past special circumstances which would warrant more extensive consideration of Class 9 accidents. Thc special circumstances fell within three categories: (I) high population density around the proposed site, i.e., above the trip points in the Standard Review Plan {NUREG 74-087, September 1975) and Regulatory Guide, 4.7, General Site Suitabiiity Crt'teria for Ãuclear Power Stations (November 1974); {2) a novel reactor design (a type of power reactor other than a light water reactor); or (3)'

combination ofa unique design and a unique siting mode.'Scc 45 FR 40102 (Junc 13, 1980): Public Scrvtcc Ekc'tri ond trat Company (Salem Nuclear Generating Station, Unit 2), DDT-17, Docket Na 50-311. "Director's Denial of Rcqucst under 10 CFR X206," at 33 a. 1I (April 16, 1980). la the first category fell the pert) aani tc, for <<hlch thc sudf pcrformcd an iafotmal assclsmcat la thc car}y site review uf the tehitiv>>

dlffcrcuccs in Qass 9 accidcut conscqucnccs smoug the altcraativc sites. 1hc Qinch River Brccdcr Reactor, a liquid metal cooled fast brccdcr reactor which is differen from the more amvcatlousI light water reactor, fell within the catcgoty ofnovel reactor design, and the staff Included a discuuiou Ia the final environmental statcmcat (NUREG4139, February 19T7) of Its consldcratioa ofQsss 9 accidcutL The floating, nuclear power plants rcprcscutcd the third catcghry of special circumsumccs, a

combination of unique design and a

uaiquc siting mode.

Bccausc the plants would be mounted on a floating barge, there would bc no soil structure to retard thc rclcasc and dispersal of activity bcucsth the plant following a core melt accident ss would be the case for land.based plants. The staff concluded that the must cxposurc likely to thc population from thc liquid pathway for s lIoating nuclear plant is signiGcantly grcatcr than tur a land-based plant.

In vlcw of the Commission's intention in Of/shore Power Systems, supro note I. that the staff bring to the Commission's attention Individual cases in ~bleb the staff bclicvcs cnviroumcutal cunscqucuccs cf CIsss 9 accidents should be cousidcrcd.

the staff rcvicwcd (FOOTNOTE CONTINUEDON NEXTPAGE )

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(II ln Public Service Company of Oklahoma the Commission noted in addition to these three criteria that proximity of a plant to a "man-made or natural hazard" might also represent "the type of exceptional case that might warrant additional consideration." The results ofthe staA's review for "special circumstances" follow.

Dhtblo Canyon As described in Section 4 of the Safety Evaluation Reports and Section 1.3 of the Final Safety Analysis Report'he Nuclear Steam Supply System for each unit of the Diablo Canyon plant is "a Westinghouse pressurized water reactor using a four-loop coolant system.

The reactor design is basically similar to that of several other Westinghouse reactor designs (Trojan, Zion 1 and 2, and D.C. Cook plants). The Diablo Canyon plant is, therefore, a typical light water reactor facility and the design is not novel.

The Diablo Canyon plant is located in a remote, undeveloped and.

relatively uninhabited region of San Luis Obispo County. Within 10 miles of the plant, the 1970 resident population density was about 20 person per square mile. Within radii of 20 and 30 miles, the densities were 55 and 40 residents per square mile, respectively.

The population densities were projected to approximately double by the year 2000. Thus remaining well.

within theguidelines of Regulatory Guide 4.7 and 10 CFR Part 100.

Therefore, population distribution near the plant is not an unusual circumstance warranting reopening or expanding proceedittgs on Diablo Canyon.

The Diablo Canyon plant also does not represent a "combination of a unique design and a unique siting mode." The Diablo Canyon site is located adjacent to the Pacific Ocean, which is the only surface water body which could be affected by liquid releases from a Class 9 accident s Ground water near the site is limited to the streambed ofDiablo Canyon Creek, an intermittent stream which empties into the ocean. The sandstone bedrock underlying station foundation if, at most, partially saturated (i.e., no water t(FOOTNOTE CONTINUEDFROM PREVIOUS PAGE) thes>> categories of special circumstances for purposes of responding to two other petitions under IO CFR 2.206 which reciuested consideration of Class 9 accidents.

Public Service Ekrrric and Gas

Company, supra, and Public Service Company of IVew Hampshire (Sesbrook Station, Units I and 2), DD-80-6. Docket Nos. N-443 and &444, "Director's Decision under IO CFR 2.206" (February I I, l980).

cSefcty Evaluation Report for Diablo Canyon Statton. Units I and 2 (October I977).

tFinsl Safety Analysis Report for the Diablo Canyon Station, Units I and 2.

sThe sta(Fuses the term "Qass 9 accident" in the ensuing discussion only for the ptttposcs of evaluating, as provided in the Commission's acw interim policy, whether "special circumstances" thai would warrant reopening, or expanding proceedings <<xist for plins which were reviewed under the now withdrawn Annex.

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table) for a considerable vertical distance. Its low permeability, combined with the lack of a near surface water table, would preclude lateral movement of contanunated water from the station toward the ocean at more than an extremely slow rate. As a minimum, many years would be available to interdict any such flow. Therefore, there are no unusual hydrogeologic features of the site which would warrant consideration ofthe environmental consequences ofa Class 9 accident.

The stafF analyzed the site characteristics and other nearby features to assure the potential for impairment of safety-related portions of station facilities due to natural or man-made hazards occurring nearby. The Safety Evaluation Report states the staff conclusion that there are no industrial, transportation, or military facilities in the area of the site which have potential to adversely affect plant safety systems.

The staff review specifically ensures that station design is adequate to accommodate other natural characteristics of the site environs.

The staff review has not identified any unusual circumstances with respect to external hazards that would warrant reopening or expanding proceedings on Diablo Canyon.

Briefly stated, none of the "special circumstances" whichWould warrant reopening or expanding proceedings is present for. the, Diablo Canyon plant. An-additional factor would weigh in favor ofnot considering special regulatory action under 10 CFR 2206. Following the occurrence of the Three Mile Island accident, the Joint Intervenors filed on May 9, 1979, a motion with the Atomic Safety and Licensing Board currently sitting in the case to reopen the record for further consideration of "Class 9" accidents at Diablo Canyon; On May 24, the NRC staff proposed that the Board defer implications for Diablo Canyon. On May 24, the"NRC staff proposed that the Board defer ruling on the motion pending completion of the staff report on TMI and its, specific, implications for Diablo Canyon. On June 5, the Board agreed to defer its ruling. The staff report has,not been completed and 'consequently the Board has not yet ruled on the motion to reopen the record for further consideration of "Class 9" accidents.

In view of the pendency of the proceedings before the Licensing Board, the stafl'believes that it would be inappropriate to institute another proceeding at the FOE's request.7 Palo Verde The Palo Verde Nuclear Generating Station, currently under construc-tion, will have tliree Combustion Engineering, Inc. "system 80" ty'pe pressurized water reactors to provide steam for the turbogenerator system.

This view is consistent with the Commission's decision in Conrolidarrd Edison Co. (Indian Point Station, Units l-3), CLI.75 8, 2 NRC l73,'77 (l975). The staff also notes the Commission has ordered that no new operating licenses may bc issued except after action of the Commission itself. "Interim Statement of Policy and Proccdurc."

44 Fed. Rrg. 58559 (October IO. I979).

Heat will be transferred from each reactor core to steam generators by circulating pressurized water in two closed loops containing two pumps in each loop. The reactors are described in detail in the Safety Evalution Report for this station (NUREG 75M8, issued on October 10, 1975) and in the Preliminary Safety Analysis Report. Reactors of similar design were used in the Perkins and Cherokee plants. The Palo Verde reactors may, therefore, be considered typical light water reactors not of a novel design.

The desert area in the immediate vicinity of the Palo Verde site is very sparsely inhabited. The 1970 population densities within radii of 10, 20, and 30 miles were 6, 7, and 7 residents per square mile, respectively. The corresponding projected densities in the year 2000 were 18, 23, 21 residents per square mile, respectively. These population densities are well within the guidelines of Regulatory Guide 4.7 and 10 CFR Part 100. Therefore, population distribution near the plant is not a "special circumstance."

The Palo Verde plant is located in an arid region which had been irrigated before 1975. Return flows. from this irrigation percolated through-the upper granular soils and perched on top of thick zone of relatively impermeable material. This perch water mound is slowly spreading laterally and downward. If this water were contaminated by severe accident, it would migrate slowly downward through the aquitard to the regional aquifer about 200 feet below the surface. The staff estimated that it would take about 5000 years for the contaminated liquid to reach water wells 2 miles south of the station. Due to this slow rate ofgroundwater movement, there would be less than average diflicultyin interdicting any radioactivity releases from a. Class 9 accident by the groundwater pathway, should such action be necessary. In view of the above considerations, there is not, in the-case ofthe Palo Verde Station, a "combination ofunique design and unique siting mode."

The staff analyzed the site characteristics and other nearby features to assess the potential for impairment of safety-related portions of station facilities due to natural or man-made hazards.

The Safety Evaluation Report states the stafl's conclusion that there were no off-site hazards which required special consideration in the design of the proposed Palo Verde facilities, except the military aircraft training flights operating out of Luke AirForce Base. The staff ha analyzed the existing AirForce program for such flights, the AirForce arrangements for notiTication of the applicant of changes in flight routes or training programs at Luke AirForce Base as-they may relate to the Palo Verde station, the probability ofaircrafl impacts on the station facilities, and experience from other sites. Supplement No.

1 to the Safety Evaluation Report states the staff conclusion that existing arrangements are acceptable.

The staff review has not identified any unusual circumstances with respect to external hazards that would warrant

special considerations of Class 9 accidents. These matters would be given further consideration by the staff in the event that there is a significant change in circumstances.

The aircraft impact issue and other safety considerations willbe examined again during operating license review.

In sum, then, there are no unusual circumstance which would warrant reopening the construction permit proceeding for Palo Verde. The staff notes, however, that the final environmental statement for the Palo Verde operating licenses will be subject to the more extensive accident analysis prescribe by the Commission's new interim policy.

Rancho Seco The Rancho Seco Nuclear Generating Station consists of a single Babcock and Wilcox pressurized water reactor with a net electrical power capacity of913 Mw. Heated pressurized water is circulated from the reactor to two steam-generators which provide steam to drive a Wcstinghouse-turbine generator. The reactor design is generally similar to that of other Babcock and Wilcox reactors such as are used at the Davis-Besse, Arkansas-1, Indian Point 1, Oconee 1-3, Crystal River 3, and Three Mile Island plants.

Following the March 28, 1979, accident at Three Mile Island, Unit 2, the NRC has placed a number ofspecial requirements on all operating reactors, particularly Babcock and Wilcox reactors, to mitumize the probability ofan accident of the Three Mile Island type. Pursuant to its Order of'May 7, 1979; 44 FR-27779, the Commission imposed requirements on the Rancho Seco facility which involve changes in reactor design, in operator training and in operating procedures. A hearing, to which FOE was a party (FOE has since withdrawn) is currently being conducted on the. Order. In addition, the Rancho Seco facility is subject to an Order, 45 FR 2447 (January 11, 1980), imposing the short-tenn "Lessons Learned" rcquirc-mcnts described in, NUREG4578. The Rancho Seco plant is currently undergoing staff review to assure that its design and operatio'n satisfy these requirements. (The Diablo Canyon and Palo Verde units will also have to mcct similar requirements and undergo staff review.) When the required changes in reactor design, operator training and operating procedures have been earned out and

approved, the staff belicvcs that there will be reasonable assurance that the Rancho Seco facility can be safely operated.

In view of these required changes and general similarity of Babcock and Wilcox design to that ofother pressurized water reactors, thc Rancho Seco design is not considered

novel, but rather typical for a land-based pressurized wafer reactor.

The Rancho Scco vicinity is sparsely populated with 1970 population densities of 19 residents per square mile within a-radius of 10 miles and 95 residents per square mile within 20 miles. Ho~ever, thc cities ofSacramento and Stockton, about 25 miles away, raise the 1970 population density to about 320 residents per square mile within a radius of30 miles. In 1972, the Sacramento County Planning Commission estimated a population increase rate of 5.2% per year, as reported in the FES. At this high rate of increase, the population in the year 2000 would quadruple that in 1970, exceeding thc population density guidelines for a 30-mile radius in Regulatory Guide 4.7.

However, the FES also reports that the California Department of Finance predicted growth rates of 1.3% per year and 1.8% per year for Sacramento and San Joaquin Counties, the most populous countics near Rancho Seco.

These growth rates resulted in population densities well within the guidelines for thc year 2000. In reviewing the FOE's petition, the staff investigated population growth data from the Sacramento County Planning Commission for thc years 1975 and 1979 for the populous counties around Rancho Scco. These factual data through the year 1979 indicate that a more realistic growth rate estimate is less than 3% per year. On this basis, the projected population in the year 2000 within 30 miles willremain within the guidelines of Regulatory Guide 4.7 and 10 CFR Part 100. Consequently, population distribution would not warrant reopening proceedings on the Rancho Seco facility.

Thc Rancho Seco Station is located on gently rolling terrain about 25 miles southeast of Sacramento.

Water bodies in the vicinity are small streams which arc normally dry except during periods of high rainfall.-The intermittent f1ow characteristics of thcsc streams indicate that they are not fed by groundwater. Liquid releases from a Class 9 accident would migrate slowly downward and southwestward into the groundwater. Using conser-vative assumptions, the staff estimates that it would take tens of years for contaminated groundwater to migrate to the nearest well which is located at the site boundary. Due to this slow rate ofgroundwater movement, the staff concludes that there are no unusual features or special'circumstances with regard to the roundwatcr contamination interdiction characteristics of this site that would distinguish it from other land-based light water reactor sites to the extent

that, under thc prcscnt Commission policy, warrants reopening environmental proceedings on Rancho Scco. The Rancho Scco Station does not represent a "combination of unique design and unique siting mode."

Thc staff analyzed the site characteristics and other nearby features to

. assess the potential for impairment ofsafety-related portions of the station.

facilities due to natural or man-made hazards.

The Safety Evaluation Report states the staff conclusion that the nature and remoteness of

industrial, transportation and military facilities in the region of the site preclude their posing a hazard to the safety features ofthe station. The staff also concluded that the station design is acceptable in relation to the geologic, seismic, and foundation conditions ofthe site. The staff review has not, therefore, identified any unusual circumstances with respect to external hazards. Thc staff would conduct further assessments and actions in the event ofsignificant changes in these circumstances.

ln summary, there are no special or unusual circumstances surrounding the Rancho Seco Station which would warrant re-opening environmental procccdings on the facility.

The staff has proposed a further detailed NRC study of the hydrologic features of all reactor sites, according to the task action plans described in Draft NUREG4660. The liquid pathway interdiction study is designated Task Action Ill.D.2. The brief discussions given above, based on currently available data, indicate that there is small likelihood of any hydrologic problems at Diablo Canyon, Palo Verde and Rancho Scco. In the event that signiTtcant possible impacts are identified in the more thorough study, methods of interdiction and mitigation will bc spcciftecL A number of mitigation methods are available, including pumping and construction of slurry walls.

III.

OTHER CONSIDERATION GIVEN TO SEVERE ACCIDENTS The FOE. emphasizes in its petition the need "to prepare to meet the possible consequences" of a serious accident at reactor sites. The staff believes that the Commission is taking positive measures to prevent severe accidents-and to mitigate their consequences.

The Commission noted a number ofthese measures in its new statement ofinterim policy on accident considerations. Among these measures taken or under consideration by the Commission and the staff are:

A proposed rule issued for public comment, 44 FR 75167 (December 19, 1979).

which would significantly revise requirements in 10 CFR Part 50 for emergency planning at nuclear power plants.

Recommendations of the Siting Policy Task Force (see NVREG4625, August, 1979) with respect to possible changes in the reactor siting policy and criteri set forth in 10 CFR Part 100. One goal of the recommendations is to consider in siting the risk associated with accidents beyond'hc design basis (i e., Chss

9) by establishing population density and distribution criteria.

Proposed "Action Plans" (see Draft NUREG4660, December 1979) for imple-menting recommendations made by bodies that have investigated the Three Mile Island accident. Among other matters these plans incorporate recommendations for rulemaking related to degraded core cooling'and core melt accidents.

Imposition of additional requirements on operating reactors, e.g., the short-term "lessons-learned" recommendations.

Scc IMI-2 Lessons Learned Task Force Status Rcport and Short-term Recommendations,"

NUREG4578 (1979), and Orders published in 45 FR 2427-2455 (January 11, 1980).

As the Commission stated in its new interim policy, "It is the Commission's policy and intent to devote NRC's major resources to matters which the Commission believes will make existing and future nuclear power plants safer, and to prevent a recurrencc of the kind of accident that occurred at Three MileIsland." 45 FR at 40104.

IV.

CONCLUSION The staff has concluded that no "special circumstances" exist which would warrant reopening environmental proceedings for the Diablo Canyon, Palo Verde, and Rancho Seco nuclear plants. In the stafFs view, the "special circumstances" standard under the Commission's new interim policy is appropriate for judging whether past NEPA reviews should bc reopened. An administrative agency is empowered to revise its policies in an evolutionary process as it gains experience in the application of the laws which the agettcy is charged to administer. See NLRB v. J. Weingarten, Inc.,

420 U.S. 251, 26547 (1975); cf. Vermont Yankee Nuclear Power CarParatian

v. Natural Resources Defense Council, 435 U.S. 519 (1978). 'I%us, a change in policy to allow broader consideration of accidents in future NEPA reviews does not invalidate thc findings in past reviews under the Annex, particularly in light ofjudicial approval of the-Commission's past practice.

See note 1 supra. By establishing a "special circutnstances" standard for reopening completed environmental reviews, the Commission has recog-nized that it may be appropriate to supplement a past environmental review under certain circumstances in view of thc transformation in policy which the Commission is undertaking. The staff does not believe, however, that such "special circumstances" are present in the three instant cases. In all events, NEPA does not require an agency to reopen the environmental record unless new information or circumstances would clearly mandate a

change in result. Greene County Planning Board v. FPC, 559 F2d 1227, 1233 (2d Cir. 1976), cert. denied, 434 U.S, 1086 (1978).

With respect to the Commission's "repudiation" of WASH-1400 as a basis for FOE's request that supplemental environmental statements bc issued, the staff notes that WASH-1400 published in draA form in )974 did not form the bases for the 1971 Annex's conclusion that the probability of occurrence of Class 9 accidents was too low to warrant their site-specific consideration under NEPA. See 45 FR at 40102; Pennsylvania Power and Light Company (Susquehanna Steam Electric Station, Units 1 and 2), LBP 79-29, 10 NRC 586, 589 (1979). The Commission's policy statement on

%ASH-1400 in light of the critique of the study by the Risk Asscmment Review Group does not provide, therefore, a basis for reopening the environmental record for the three plants at issue.

Finally, the staff again notes that the Conmussion has taken several actions by rulemaking and by order to assure that adequate measures are taken to prevent serious accidents, like the one at Three Mile Island, and to mitigate the consequences ofserious accidents. In view ofthe foregoing, the petition of the FOE is denied.

A copy of this decision will also be filed with the Secretary for the Commission's review in accordance with 10 CFR 2206(c) of the Commis-sion's regulations.

As provided in 10 CFR 2206(c),

this decision will constitute the fmal action ofthe Commission twenty (20) days after the date of issuance, unless the Commission on its own motion institutes the review ofthis decision within that time.

Dated at Bethesda, Maryland this 19th day of June 1980 Harold R. Denton, Director.

OQice of Nuclear Reactor Regulation

Cite as 13 NRC 1122 (1981)

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION ATOMIC SAFETY AND LICENSING BOARD LBP-81-17 Before Admlnistrittive Judges:

John F. Wolf, Chairman Mr. Glenn O. Bright Dr. Jerry R. Kllne In the Matter ol

/

PACIFIC GAS 8c ELECTRIC COMPANY-(Dlablo Canyon Nuclear Power-Plant, Unit Nos.

1 and 2)

Docket Nos. 50-275-OL 56423-OL.

(Low Power Test)

Proceeding June 19, 1981 The Licensing Board denies interveaors'otioa to reopen the record for consideration of Class 9" accidents at Diablo Canyon on the ground that ao special circumstances exist to warraat such consideration.

MEMORANDUM AND ORDER DENYING JOINT INTERVENORS MOTION TO REOPEN ENVIRONMENTALRECORD FOR CONSIDERATION OF CLASS NINE ACCIDENT Following the occurrence of the Three Mile Island accideat, Joint Intervenors filed on May 9; 1979 a motion with thc Board to reopen the record for further consideration of "Qass 9" accidents at Diablo Canyo yon.

May 24, 1979, the Staff proposed that the Board defer ruling on thc motion pending completion of the Staff report oa TMI and its specific implications to this case. On June 5, 1979, thc Board agreed to the StafFs proposal. The Boards now finds that it has suQicient informatioa to rule on the motion.

1122

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In November 1980, the Commission published NUREG4737, "Clarifi-cation ofTMIAction Plan Requirements," which sets forth those items of the total TMI-related actions contained in the StafI's TMI Action Plan, NUREG4660, which have been approved by the Commission for imple-mentation by licensees of operating reactors and Applicants for operating licenses. The Board has also received guidance from the Commission laying out the procedures to be used in our application of NUREGW737 in our licensing process (CLI-8542, December 18, 1980, and CLI-81-5, dated Ap'ril 1, 198 1). We have carefully reviewed these documents, and find that none of the requirements therein impact the Commission's interim policy on accident considerations.

We therefore proceed with our analysis of the Diablo Canyon situation.

On May 16, 1980, the Commission issued a statement ofinterim policy which provided guidance on consideration ofClass 9 accident analysis with respect to plants for which Final Environmental Statements had been issued. This guidance stated that in these cases consideration of Class 9 accidents need not be addressed absent a showing ofspecial circumstances.

The Commission noted.<hat in the past the Staff has identified such special circumstances as falling within three categories:

(1) high population density around the site; (2) a novel reactor design; or (3) a combination ofa unique design and a unique siting mode. Diablo Canyon does not fall into any ofthese categories (cf. DD-80-22, 11 NRC 919 (1980)).

The Commission had earlier noted that in addition ot these tEree criteria that. proximity of'a plant to a "man-made or natural hazard" might also represent "the type of exceptional case that might warrant additional.

consideration"'(Public Service Company of Oklahoma (Black Fox Station,.

Units 1 and 2), CLI-80-8, at 434-435 (March 21, 1980)), In response to this

guidance, the Board believed that the known seismicity of the State of California might constitute such a natural hazard.

The Board conducted exhaustive hearings on the eFects ofseismic forces on the Diablo Canyon plants from December, 1978 through February, 1979. In our Partial Initial Decision issued September 27, 1979, we found that

"... the evidence demonstrates that aH structures, systems and compo-nents of the Diablo plant necessary for continued operation without undue risk to the health and safety ofthe public wiHremain functional and within applicable stress and deformation limits when subjected. to the effects of the operating basis earthquake in combination with normal operating loads."

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In June, 1980 the Atomic Licensing and Appeal Boaid reopened the record to receive new evidence not available to the Licensing Board at the time they issued their decision. After conducting a thorough inAepth-review of both the new evidence and the evidence before the Licensing Board, the Appeal Board affirmed the Licensing Board's findings (ALAB-644, June 16, 1981). We must, therefore, conclude that even though Diablo Canyon is located in a region of known seismicity, the'probability of it sustaining a "class nine" accident is no greater than for any other reactor.

Thus no special circumstances exist, and the motion to reopen the record for consideration ofclass nine accidents is denied.

On the 19th day ofJune, 1981 itis ORDERED that the motion to reopen the record for consideration of class nine accidents is denied.

FOR~ ATOMIC SAFEIY AND LICENSING BOARD Issued at Bethesda, Maiyland this 19th day of June, 1981 John F. Wolf, Churnian ADMINISTRATIVEJUDGE