ML25196A271

08-19-77 Report on Further Partial Review of Diablo Canyon Nuclear Power Station Units 1 and 2

ML25196A271
Person / Time
Site:	Diablo Canyon
Issue date:	08/19/1977
From:	Bender M Advisory Committee on Reactor Safeguards
To:	Hendrie J NRC/Chairman
References
Download: ML25196A271 (1)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 August 19, 1977 Honor able Joseph M. Hendrie Chairman U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

REPORI' ON FURl'HER PARl'IAL REVIEW OF DIABLO CANYON NUCLEAR PCMER STATIOO UNITS 1 AND 2

Dear Dr. Hendrie:

During its 208th meeting, August 11-13, 1977, the Advisory Comnittee on Reactor Safeguards continued its review of the application of the Pacific Gas and Electric Company for authorization to operate the Diablo Canyon Nuclear Power Station Units 1 and 2. The Committee re-ported previously on this application in its letter of June 12, 1975.

Since that time, several meetings of a Subcomnittee and of the full Canmittee have been held to review and discuss questions relating to the seismic design bases and criteria, and a Subcomnittee meeting was held in Des Plaines, Illinois on August 2, 1977 to review safety matters not related to seismic concerns. This report is related only to those nonseismic matters. During its review, the Comnittee had the benefit of discussions with representatives and consultants of the Pacific Gas and Electric Company, the Westinghouse Electric Corporation, the Nuclear Regulatory Commission Staff, and a consultant to intervenors in the public hearings before an NRC Atomic Safety and Licensing Board. The Canmittee also had the benefit of the documents listed.

The original emergency core cooling system performance analyses had been made using an initial upper head temperature corresponding to the core inlet temperature. These analyses have been redone using an upper head terperature corresponding to that in the hot leg. Calculations using the latest Westinghouse evaluation rrodel (October 1975 revision) show carrpliance with the criteria of 10 CFR 50.46 with a peaking factor of 2.32.

In its letter of June 12, 1975, the Comnittee noted that the Diablo Canyon units were expected to be among the first reactors of this type to operate at a power as high as 3411 M"wt and with a full core of the 17xl7 fuel assembies, and noted further that an augmented start-up program and a m:>re cautious than normal.approach to full power would be desirable for such plants. In the interim, the recomnended augmented start-up program has been enployed for the Trojan and Beaver Valley reactors, which are in the categories described above.

In view of this experience, and subject 349

Honorable Joseph August 19, 1977 to conpletion of the Staff's revie.-, of the reports on these start-up pro-grams, the Conmittee does not believe it will be necessary to inpose special restrictions on the start-up and pooer escalation programs for the Diablo Canyon units beyond those normally considered prudent by the NOC Staff.

The design of Unit 1 has been IOOdified and augmented to provide protection against the possible adverse effects of postulated breaks and cracks in high-energy fluid piping systems outside containment. The NRC Staff has found these systems in compliance with its current criteria. The Com-mittee concurs. Similar but not identical IOOdifications are being made to Unit 2, which differs from Unit 1 in certain respects. These provisions for Unit 2 have not yet been revie.-,ed by the NRC Staff, but compliance with current criteria will be required. This matter should be resolved in a manner E\\atisfactory to the NRC Staff.

The Applicant has proposed several rrodifications to his design, adminis-trative procedures, and operator training, to minimize the likelihood of an overpressure transient in the reactor coolant system at temperatures below operating temperatures during startup or shutdown.

The Staff has revie.-,ed these modifications and has found them acceptable as an interim measure. The Applicant is a member of an "Owner's Group" cooperating with the reactor vendor in seeking a permanent solution to this generic problem, and has agreed to implement that solution when it is found acceptable to the Staff. The Corrrnittee agrees that the interim measures are acceptable, and wishes to be informed of the final generic solution.

At the request of the NRC Staff, the Applicant has reevaluated his pro-cedures and systems for the prevention, detection and suppression of fires as part of a generic revie.-, of these features of all plants operating or under construction. This revie.-, has been conducted in accordance with the provisions of Appendix A to Branch Technical Position APCSB 9.5-1 as mod-ified by the provisions of Regulatory Guide 1.120 and Proposed Revision 1 thereto. The Applicant has proposed, and has provided a schedule for im-plementation of, various modifications to the plant. This matter should be resolved in a manner satisfactory to the NRC Staff.

The Applicant's emergency plans were revie.-,ed prior to the Corrmittee's letter of June 12, 1975 and found acceptable. A change in the plans relating to arrangements with a hospital to accept contaminated patients has been proposed by the Applicant, but has not yet been revie.-,ed by the Staff. This matter should be resolved in a manner satisfactory to the NOC Staff.

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Honorable Joseph August 19, 1977 The Applicant described the instrumentation available to t00nitor the course of an accident. The Comnittee does not believe that the instru-mentation provided for this purpose meets the full intent of that pro-posed in Revision 1 of Regulatory Guide 1.97. The Comnittee recomnends that the provisions of that Guide be implemented by the Applicant for the Diablo Canyon Station in a timely manner once the Regulatory Guide has been officially promulgated. The Conmittee wishes to be kept informed.

The Applicant has modified his Security Plan in conformance with the re-quirements of 10 CFR 73.55. The Staff has reviewed this plan and a Security Plan Review Team has visited the plant site. Although the Staff review has not been completed, the Applicant has stated that both the security plan and the physical changes and additions to the plant will be in accord with the regulations on the effective dates specified therein.

This matter should be resolved in a manner satisfactory to the NRC Staff.

In both written reports and in oral presentations to the ACRS a consultant to intervenors in the public hearings before an NRC Atomic Safety and Licensing Board has alleged serious deficiencies in the Applicant's Quality Assurance programs for design, construction, and operation. These alle-gations have been reviewed by the NRC Staff, and their findings reported to the Corrnnittee. The Staff has found no deficiencies in these programs of a nature serious enough to affect the safe operation of the plant.

The Committee concurs.

The Committee has not completed its review of several chiefly seismic-related matters, including:

the seismic design bases and criteria, the adequacy of the seismic design, the requirements with regard to protection against tsunamis, the qualification of electrical equipment and instru-mentation for the postulated accident environment or for seismic effects, and the acceptability of the design of the reactor pressure vessel supports to resist forces resulting from a loss-of-coolant accident or from a seismic event. The Corrnnittee will complete its review of these matters following completion of a review by the NRC Staff.

With regard to the generic problems cited in the Comnittee's report, "Status of Generic Items Relating to Light-Water Reactors:

Report No. 5," dated February 24, 1977, those items considered relevant to the Diablo Canyon Station are: II-1, 2, 3, 4, 5, 6, 7, 9; IIA-3, 4, 5, 6, 7; IIB-2; IIC-1, 2, 3, 4, 5; IID-2. These problems should be dealt with by the Staff and the Applicant as solutions are found.

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Honorable Joseph August 19, 1977 Except for those matters identified above as requiring further Comnittee review, the ACRS believes that, if due consideration is given to the fore-going, and subject to satisfactory completion of construction and pre-operational testing, there is reasonable assurance that the Diablo Canyon Nuclear Power Station Units 1 and 2 can be operated at power levels up to 3338 and 3411 MW(t), respectively, without undue risk to the health and safety of the public.

The Carmittee will report in the future on those matters for which its review has not yet been conpleted.

References Sincerely cm.

M. Bender Chairman

1. Final Safety Analysis Report (FSAR) for the Diablo Canyon Nuclear Power Station, Units 1 and 2, and Amendnents 1-51 to the FSAR.

2. Safety Evaluation Report dated October 16, 1974, and Supplements 1-6 dated January 31, 1975, May 9, 1975, September 18, 1975, May 1976, September 1976, and July 1977.

3. Docwnents provided to the Comnittee by Richard B. Hubbard, Technical Consultant to Intervenors in the Public Hearings Before an NRC Atomic Safety and Licensing Board.

a. Diablo Canyon Nuclear Power Plant, Units No. 1 and 2, Atomic Safety and Licensing Board (ASLB), Affidavit of Richard B. Hubbard, March 10, 1977.

b. Diablo Canyon Nuclear Power Plant, Units No. 1 and 2, ASLB, Supplemental Affidavit of Richard B. Hubbard, April 27, 1977.

c. Written Statement dated June 23, 1977 from Richard B. Hubbard to ACRS Subcommittee on Diablo Canyon concerning, Seismic Risk Uncertainty Deficiencies in Diablo Canyon QA Program and its Implementation.

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Honorable Joseph M. Hendrie

-s-August 19, 1977

d. written Statement dated June 30, 1977 from Richard B. Hubbard to Subcomnittee on Energy and the Environment, Comnittee on Interior and Insular Affairs, United States House of Representatives, Washington, D.C. concerning Effectiveness of NRC Regulations - Modifications to Diablo canyon Nuclear Units.

e. Written Statement dated August 2, 1977 from Richard B.

Hubbard to ACRS Subcommittee on Diablo Canyon concerning Risk Uncertainty Due to Flaws in Diablo Canyon QA Program and Failure to Implement Current NRC Practices.

f. Written Statement dated Augllst 12., 1977 from Richard B. Hubbard to the ACRS on Diablo Canyon concerning Risk Uncertainty Due to Deficiencies in Diablo Canyon Quality Assurance Program and Failure to Implement Current NRC Practices.

4. NRC Staff Report received August 2, 1977 by ACRS Subcommittee on Diablo Canyon concerning first four statements by Richard B. Hubbard.

5. Pacific Gas and Electric Company letters to the NRC as follows:

a. Prevention of Primary System OVerpressurization, July 5, 1977.

b.

ECCS Analysis, June 10, 1977.

c. ATWS, September 30, 1976.

d. Reactor Vessel Support Structure, January 13, 1976.

e. Pipe Breaks Outside of Containment, January 14, 1976.

6. Diablo Canyon Power Plant Physical Security Plan, Rev. 6, July 22, 1977 (Conpany Confidential to be withheld from public disclosure in accordance with 10 CFR 2.790).

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