ML16341G441

Forwards Safety Evaluation & Technical Evaluation Rept Concluding That Facility Should Be Classified Into Emergency AC (EAC) Power Configuration Group A.Revised Response Due within 60 Days

ML16341G441
Person / Time
Site:	Diablo Canyon
Issue date:	01/29/1992
From:	Rood H Office of Nuclear Reactor Regulation
To:	Rueger G PACIFIC GAS & ELECTRIC CO.
Shared Package
ML16341G442	List: ML16341G441 ML16341G443
References
TAC-M68537, TAC-M68538, NUDOCS 9202140009
Download: ML16341G441 (10)

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UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 january 29, 1992 Docket Nos.

50-275 and 50-323 Hr. Gregory M. Rueger Senior Vice President and General Manager Nuclear Power Generation Business Unit Pacific Gas and Electric Company 77 Scale Street, Room 1451 San Francisco, California 94106

SUBJECT:

SAFETY EVALUATION OF DIABLO CANYON STATION BLACKOUT ANALYSIS (TAC NOS.

M68537 AND H68538)

The U.S. Nuclear Regulatory Commission (NRC) staff and a staff contractor (Science Applications International, or SAIC) have reviewed your submittals dated April 17,

1989, March 30,

1990, and August 15, 1991, related to 10 CFR 50.63, the Station Blackout (SBO) Rule.

The results of the staff

. review are given in the enclosed Safety Evaluation (SE) by the NRC staff and the attachment to the SE, a Technical Evaluation Report (TER) by SAIC.

Your SBO submittals conclude that Diablo Canyon should be classified into emergency ac (EAC) power configuration group "A", subsequent to the installation of the 6th diesel generator.

This conclusion is based on the capability to operate safe shutdown equipment at one unit with one emergency diesel generator (EDG) following a loss of offsite power (LOOP), in the event that only one EDG is available.

In this event, some normally connected loads (the containment fan cooler units) would be dropped and normally separate electrical busses would be cross-connected.

The staff recognizes that this capability is a safety benefit.

However, the staff criteria for determining the EAC category (which is part of establishing the required coping'uration) for a nuclear facility is based on the EDG configuration; that is, the number of EDGs normally available and the number required for normal safe

shutdown, including ac powered decay heat removal

systems, in the event of a LOOP.

Further, credit is not given for actions that could add to the burden of the plant operatorswho, are'already in a high-stress environment, such as load switching or disabling of; information readouts or alarms in the control room.

Load shedding and~,load switching are considered a degradation of the normal safe shutdown capability. for the LOOP condition.

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Mr. Gregory M. Rueger Based on this criteria, the enclosed SE finds that the EAC group at Diablo Canyon is category "D", because two EDGs are required to supply the normal safe shutdown loads without load shedding or switching.

Since the EAC power configuration is "D", a target EDG reliability of 0.975 is required in order to meet the guidance of Section 3.2.4 of NUMARC 87-00 for attaining a 4-hour duration SBO (the staff SE assumes a 4-hour duration).

Also, based on the information you have provided, the plant batteries do not have sufficient capacity to supply the SBO loads for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Therefore, the staff SE finds that Diablo Canyon does not conform to the SBO Rule, the guidance of Regulatory Guide (RG) 1.155, NUMARC 87-00, and NUMARC 87-00 Supplemental Questions/Answers and Major Assumptions, dated December 27, 1989 (issued to the industry by NUMARC on January 4,

1990).

The areas of nonconformance are identified in the enclosed SE.

In addition, the following areas may require follow-up inspection by the NRC to verify that the implementation of any modifications and the supporting documentation which you may propose as a result of this evaluation are adequate to meet the SBO Rule.

The NRC staff is developing guidance for this follow-up inspection to verify that:

a.

Hardware and procedure modifications are acceptable, b.

SBO procedures are in accordance with Position 3.4 of RG 1. 155 and with Section 4 of NUMARC 87-00, c.

Operator staffing and training to follow the identified actions in the procedures, d.

The EDG reliability program meets, as 'a minimum, the guidelines of RG 1.155, e.

Equipment and components required to cope with an SBO are incorporated in a QA program that meets the guidance of RG 1. 155, f.

Actions are taken to comply with the specific recommendations made in the SE.

The guidance provided on Technical Specifications (TS) for an SBO states that the TS should be consistent with the Interim Commission Policy Statement on Technical Specifications.

The NRC staff takes the position that TS are required for SBO response equipment.

However, the question of how specifications for the SBO equipment will be applied is currently being considered generically by the NRC staff in the context of the Technical Specification Improvement Program and remains an open item at this time.

In the interim, the staff expects that plant procedures will contain appropriate testing and surveillance requirements to assure the operability of the necessary SBO equipment.

If the staff later determines that TS for SBO equipment is warranted, licensees will be notified of the implementation requirements for such TS.

Mr. Gregory M ~ Rueger 3

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A revised response to the SBO Rule which addresses the areas of non-conformance identified in the enclosed SE should be submitted for staff review within 60 days.

Until an acceptable resolution of the identified non-conformances is achieved, the issue of conformance to the SBO Rule will remain open for Diablo Canyon 1 and 2. If you have any questions regarding this

issue, please contact me.

Sincerely,

Enclosures:

Safety Evaluation Report cc w/encl:

See next page Harry Rood, Senior Project Manager Project Directorate V

Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation DISTRIBUTION Docket Filets NRC 8

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Hr. Gregory M. Rueger A revised response to the SBO Rule which addresses the areas of non-conformance identified in the enclosed SE should be submitted for staff review within 60 days.

Until an acceptable resolution of the identified non-conformances is achieved, the issue of conformance to the SBO Rule will remain open for Diablo Canyon 1 and 2 ~

If. you have any questions regarding this

issue, please contact me.

Sincerely, Harry Rood, Senior Project Hanager Project Directorate V

Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation

Enclosures:

Safety Evaluation Report cc w/encl:

See next page

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Hr. Gregory H. Rueger Pacific Gas and Electric Company Diablo Canyon CC:

Regional Administrator, Region V

U.S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P.

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Box 369 Avila Beach, California 93424 Hr. Peter H.

Kaufman Deputy Attorney General State of California 110 West A Street, Suite 700 San Diego, California 92101 Richard F. Locke, Esq.

Pacific Gas

& Electric Company Post Office Box 7442 San Francisco, California 94120 Mr. John Hickman Senior Health Physicist Environmental Radioactive Hgmt. Unit Environmental Hanagement Branch State Department of Health Services 714 P Street, Room 616 Sacramento, California 95814 Hichael M. Strumwasser, Esq.

Special Assistant Attorney General State of California Department of Justice 3580 Wilshire Boulevard, Room 800 Los Angeles, California 90010 Hanaging Editor The Count Tele ram Tribune 1321 Johnson Avenue P.

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Box 112 San Luis Obispo, California 93406 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, California 93408 Ms. Sandra A. Silver Hothers for Peace 660 Granite Creek Road Santa Cruz, California 95065 Dr.

R.

B. Ferguson, Energy Chair Sierra Club California 6715 Rocky Canyon Creston, California 93432 Ms. Nancy Culver 192 Luneta Street San Luis Obispo, California 93401 Ms. Jacquelyn C. Wheeler 3303 Barranca Court San Luis Obispo, California 93401

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