ML13317A562
| ML13317A562 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/30/1983 |
| From: | Paulson W Office of Nuclear Reactor Regulation |
| To: | Dietch R Southern California Edison Co |
| References | |
| TAC-62079, TASK-07-02, TASK-7-2, TASK-RR LSO5-83-03-045, LSO5-83-3-45, NUDOCS 8304060311 | |
| Download: ML13317A562 (5) | |
Text
Mardh 30, 1983 Docket No. 50-206 LS05-83-03-045 Mr. R. Dietch, Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770
Dear Mr. Dietch:
SUBJECT:
SEP TOPIC VII-2, ENGINEERED SAFETY FEATURES (ESF) SYSTEM CONTROL LOGIC AND DESIGN, FINAL SAFETY EVALUATION FOR SAN ONOFRE UNIT 1 The staff's final safety evaluation report on this topic is enclosed.
Our draft report of November 17, 1981, has been revised to reflect the comments provided by a letter from R. W. Krieger to D. M. Crutchfield dated February 28, 1983.
For the reasons discussed in the safety evaluation, we consider this topic to be complete. This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic is modified before the integrated assessment is completed.
Sincerely, Original signed by/
Walter A. Paulson, Project Manager Operating Reactors Branch #5 Division of Licensing
Enclosure:
As stated cc w/enclosure:
See next page 8304060311 830330 PDR ADOCK 05000206 P
PDR OFFICE
.SEPB:
SEPB:D SEPB: DL O
EB:L OR0B#5:BC
- dk EMcKenna CGrimes WRussell WP n
D~rutchfie S U R N A M E.
DATE V
3 3/.5/83 331(0/83 3/83 3/
7/832I 3/7 /83
___OY__18356 NRC FORM 318(00-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-90
Mr. R. Dietch, Vice Preo nt Docket No. 50-206 Nuclear Engineering and Operations San Onofre 1 Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770 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 Post Office Box 1831 San Diego, California 92112 Resident Inspector/ San Onofre NPS c/o U.S. Nuclear Regulatory Commission Post Office Box 4329 San Clemente, California 92672 Mayor City of San Clemente San Clemente, California 92672.
Chairman 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 U.S. Nuclear Regulatory Commission, Region V 1450 Maria Lane Walnut Creek, California 94596
SYSTEMATIC EVALUATION PROGRAM TOPIC Vrr-2 SAN ONOFRE TOPIC:
VII-2, ENGINEERED SAFETY FEATURES (ESF) SYSTEM CONTROL LOGIC AND DESIGN I.
INTRODUCTION During the staff review of the Safety Injection System (SIS) reset (issue
- 4 in NUREG-0138) the staff determined that the Engineered Safety Features Actuation Systems (ESFAS) at both PWRs and BWRs may have design features that raise questions about the independence of redundant channels, the interaction of reset features and individual equipment-controls, and the interaction of the ESFAS logic that controls transfers between on-site and off-site power sources.
Review of the as-built logic diagrams and schematics, operator action required to supplement the ESFAS automatic actions, the startup and surveillance testing procedures for demonstrating ESFAS performance appeared to be required.
Several specific concerns exist with regard to the manual SIS reset feature following a LOCA. They are: (1) if a loss of offsite power occurs after reset, operator action would be required to remove normal shutdown cooling loads from the emergency bus and re-establish emergency cooling loads.
Time would be critical if the loss of offsite power occurred within a few minutes following a LOCA, (2) if loss of offsite power occurs after reset, some plants may not restart some essential loads such as diesel cooling water, (3) the plant may suffer a loss of ECCS delivery for some time period before emergency power picks up the ECCS system. It was also decided to review the ESF system control logic and design, including bypasses, reset features and interactions with transfers between onsite and offsite power sources.
Since these decisions were made in early 1977, the staff's plans for re solving these issues have changed. Two generic reviews of the diesel generator problems have been conducted by Inspection and Enforcement.
The second review includes consideration of bypasses and resets. In addition, Task Action Plan Generic Task B-24 is involved with reset and bypass concerns. Accordingly, this SEP topic has been modified to reduce duplication of effort.
As a result of the staff's review of the scope of the several related generic efforts and the other SEP topics, it was decided that the only, area that had not been covered was the independence of redundant logic trains.
Independence might be comDromised by sharing input signals and the use of common controls such as mode switches, reset switches, and logic test facilities.
-2 II. REVIEW CRITERIA The current licensing criteria are presented in Section 2 of EG&G Report 0543J, "ESF System Control Logic and Design."
III.
RELATED SAFETY TOPICS AND INTERFACES The scope of review for this topic was limited to avoid duplication of effort since some aspects of the review were performed under related topics. The related topics and the subject matter are identified below.
Each of the related topic reports contain the acceptance criteria and review guidance for its subject matter.
111-6 Seismic Qualification III-11 Seismic Qualification 111-12 Environmental Qualification IV-l.A Operation with Less Than All Loops in Operation VI-4 Bypass and Reset of Engineered Safety Features (B-24)
VI-7.A.3 ECCS Actuation System VI-7.B ESF Switchover from Injection to Recirculation VI-7.C.1 Independence of Onsite Power VI-7.C.2 Failure Mode Analysis-ECCS VI-7.C.3 The Effect of Loop Isolation Valve Closure on ECCS Performance VI-7.D Long Term Cooling Passive Failures (e.g., flooding)
VI-7.F Accumulator Isolation Valves VI-10.A Testing of Reactor Protection'Systems VI-10.B Shared Systems VII-1.A Reactor Trip System Isolation VII-3 Systems Required for Safe Shutdown VIII-2 Onsite Emergency Power Systems VIII-3 Emergency dc Power Systems VIII-4 Electrical Penetrations IX-3 Ventilation IX-6 Fire Protection The conclusion that suitable isolation devices are-provided i~s a basic assumption for Topics VI-7.C.2 and VII-3.
IV. REVIEW GUIDELINES The review guidelines are presented in Section 3 of Report 0543J, "ESF System Control Logic and Design."
V.
EVALUATION A description of the isolation devices employed in the San Onofre Unit 1 and a comparison with current design criteria are presented in Report 0543J,."ESF System Control Logic and Design.'
-3 Since the staff's draft evaluation on this topic was issued, the licensee has provided additional design 'information and described modifications made as a result of TMI. These major sources of additional information are a letter from R. W. Krieger to D. M. Crutchfield dated February 28, 1983 and a previous letter (not available to our contractor) dated August 9, 1979. These documents indicate that additional Foxboro bistables have been provided. In addition, the licensee provided layout and schematic drawings of the input buffer modules (6N213) and more detailed systems descriptions.
From our review of these documents, the staff has determined that relay or photo-diode isolation is used. The individual components provide suitable signal isolation, but the wiring to and from these isolators do not satisfy current criteria for physical separation.
This problem was also identified by the licensee in the resolution of 10 CFR 50 Appendix R concerns (SEP Topic IX-6).
This staff concern has been resolved by the licensee commitment to provide new instrumentation and controls at a new remote shutdown panel.
The staff's review of the Appendix R resolution indicates that the instrumentation and controls that are to be provided will provide sufficient information to permit safe shutdown.
VI.
CONCLUSION As a result of our review of our contractor's work and additional infor mation that was not available to our contractor, the staff has concluded that modifications proposed by the licensee and approved by the staff will bring the design of the instrumentation and controls needed for safe shotdown into conformance with the acceptance criteria for this topic.
The design, however, does not satisfy current criteria for emergency core cooling systems. Since, Emergency Core Cooling reviews are a part of SEP Topic VI-7.C.2, the staff considers Topic VII-2 to have been satisfactorily completed for this plant.