ML13317A154

Forwards Final Safety Evaluation Re SEP Topic VII-03, Sys Required for Safe Shutdown. Conclusions Have Been Modified. Basis for Revision Is Discovery That Component Cooling Water Surge Tank Level Indication Does Not Satisfy Criterion

ML13317A154
Person / Time
Site:	San Onofre
Issue date:	06/04/1982
From:	Paulson W Office of Nuclear Reactor Regulation
To:	Dietch R Southern California Edison Co
References
TAC-44652, TAC-62079, TASK-07-03, TASK-7-3, TASK-RR LSO5-82-06-012, LSO5-82-6-12, NUDOCS 8206080278
Download: ML13317A154 (4)

Text

June 4, 1982 Docket No. 50-206 LS05-82-06-012 Mr. R. Dietch, Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770

SUBJECT:

SEP TOPIC VII-3, SYSTEMS REQUIRED FOR SAFE SHUTDOWN FINAL SAFETY EVALUATION FOR SAN ONOFRE UNIT 1 Our Final Safety Evaluation Report on this subject is enclosed. Out report and conclusions have been modified from that forwarded by our letter from D. Crutchfield to R. Dietch dated November 18, 1981.

The basis for our revised report is the discovery that the component cooling water surge tank level indication does not satisfy the single failure criterion.

We recommend that a redundant, Class 1E surge tank level indication system be installed. The need to actually install such a system will CIL be determined during the integrated safety assessment for San Onofre T

Unit 1.

(A This evaluation may Tbe revised in the future if your facility design is changed or if NRC criteria relating to this subject are modified ADZ' before the integrated assessment is completed.

s4/iy Sincerely, E.

Original signed by' Walter Paulson, Project Manager Operating Reactors Branch No. 5 Division of Licensing Enclogure:

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Y'r. R. Dietch San Onofre Unit 1 Docket No. 50-206 Revised.3/30/82 cc Charles R. Kocher, Assistant General Counsel James Beoletto, Esquire Southern California Edison Company Post Office Box 800 Rosemead, California 91770 David R. Pigott Orrick, Herrington & Sutcliffe 600 Montgomery Street San Francisco, California 94111 Harry B. Stoehr San Diego Gas & Electric Company P. 0. Box 1831

.San Diego, California 92112 Resident Inspector/San Onofre NPS c/o U. S. NRC P. 0. Box 4329 San Clemente, California 92672 Mayor City of San Clemente San Clemente, California 92672 Chairman 4

Board of Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN:

Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814 U. S. Environmental Protection Agency Region IX Office ATTN:

Regional Radiation Representative 215 Freemont Street San Francisco, California 94111 Robert H. Engelken, Regional Administrator Nuclear Regulatory Commission, Region V 1450 Maria Lane Walnut Creek, California 94596

SYSTEMATIC EVALUATION PROGRAM TOPIC VII-3 SAN'ONOFRE UNIT 1 TOPIC: VII-3, Systems Required For Safe Shutdown I.

INTRODUCTION The systems aspects of the review of Systems Required for Safe Shutdown was conducted as part of Topic V-10.B (RHR Reliability). This safety evaluation is limited to the electrical instrumentation and control sys tems identified as being required for safe shutdown. Plant systems that are needed to achieve and maintain a-tafe shutdown condition of the plant, including the capability for prompt hot shutdown of the reactor from out side the control room were reviewed. Included also, was a review of the design capability and method of bringing the plant froma high pressure condition to low pressure cooling assuming the use of only safety grade equipment. The objectives of the review were to assure:

A. The design adequacy of the safe shutdown system to (a) initiate automatically the operation of appropriate systems, including the reactivity control systems, such that specified acceptable fuel design limits are not exceeded as a result of anticipated opera tional occurrences or postulated accidents and (b) initiate the operation of systems and components required to bring the plant to a safe shutdown.

B. That the.required systems and equipment, including necessary in strumentation and controls to maintain the unit in a safe condition during hot shutdown, are located at appropriate places outside the control room and have a potential capability for subsequent cold shutdown of the reactor through the suitable procedures.

C. That only safety grade equipment is required to bring the reactor coolant system from a high pressure condition to a low pressure cooling condition.

II. REVIEW CRITERIA The review criteria are presented in Section 2 of EG&G Report 0402J, "Electrical, Instrumentation, and Control Features of Systems Required for Safe Shutdown."

III.

RELATED SAFETY TOPICS AND INTERFACES Review areas outside the scope of this topic and safety topics that are dependent on the present topic information for completion are identified in Section 3 of EG&G Report 04023.

-2 IV.

REVIEW GUIDELINES The review guidelines are presented in Section 4 of EG&G Report 0402J.

V.

EVALUATION As noted in EG&G Report 0402J, the systems required to take San Onofre Unit 1 from hot shutdown to cold shutdown, assuming only offsite power is available or only onsite power is available and a single failure, are capable of initiation to bring the plant to a safe shutdown and are in compliance with current licensing criteria and the safety objectives of SEP Topic VII-3 except that long-term cooling (RHR) is susceptable to single EI&C failures which render long-term cooling inoperable.

With the exception of the component cooling system, the instrumentation available to control room operators to place and maintain the reactor in cold shutdown conditions meets current licensing criteria since no single EI&C failures render vital parameters such as reactor pressure, temperature, etc., inoperable.

The capability to maintain the reactor in hot shutdown from outside the control room exists and is in compliance with the safety objectives of SEP Topic VII-3. Procedures to take the plant from hot to cold shutdown from outside the control room satisfy the safety objectives of SEP Topic VII-3.

The component cooling water surge tank level is monitored by three level devices. These devices are a high level alarm, a low level alarm and a local sight gauge. Make up is manually controlled. Given a leak in the component cooling system and a failure of the low level alarm, the cool ing system may be lost.

VI.

CONCLUSIONS The long term cooling method (RHR) is susceptible to single EI&C failures which render it inoperable. However, because alternative methods of long term cooling are available which were not addressed by the contractor (see SEP Safe Shutdown Systems Report, transmitted by letter dated June 20, 1981), the staff concludes that San Onofre Unit 1 satisfies all of the review criteria except for the component cooling water system.. The staff proposes that a redundant, Class 1E surge tank level indication system be installed.