IR 05000206/1990018
| ML13329A146 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/10/1990 |
| From: | Johnson P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML13329A145 | List: |
| References | |
| 50-206-90-18-MM, 50-361-90-18, 50-362-90-18, NUDOCS 9004300258 | |
| Download: ML13329A146 (20) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION
REGION V
Report No /90-18, 50-361/90-18, 50-362/90-18 Docket No, 50-361, 50-362 License No DPR-13, NPF-10, NPF-15 Licensee:
Southern California Edison Company Irvine Operations Center 23 Parker Street Irvine, California 92718 Facility Name:
San Onofre Units 1, 2 and 3 Meeting at:
Walnut Creek, California Meeting conducted:
March 14, 1990 Prepared by:
C. W. Caldwell, Senior Resident Inspector Approved By:
(74
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1 co P. H. ohnson, Chief Date Signed Summary Reac o Projects Section 3 A Management Meeting was held on March 14, 1990 to discuss issues related to Unit 1 deficiencies identified and reported by the licensee during the past year, including the safety injection alignment delay discussed in Licensee Event Report 89-11, Revision 1. In addition, the licensee provided a status on engineering program improvements and the Design Basis Documentation (DBD)
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DETAILS 1. Meeting Participants Nuclear Regulatory Commission J. Martin, Regional Administrator R. Zimmerman, Director, Division of Reactor Safety and Projects C. Trammell, Acting Director, Project Directorate V, NRR A. Johnson, Enforcement Officer S. Richards, Chief, Reactor Projects Branch P. Johnson, Chief, Reactor Projects Section 3 R, Huey, Chief, Engineering Section C. Caldwell, Senior Resident Inspector L. Kokajko, Units 2 and 3 NRR Project Manager J. Tatum, Unit 1 NRR Project Manager Southern California Edison Company H. Ray, Vice President, Nuclear Engineering, Safety, and Licensing (NES&L)
D. Nunn, Manager of Nuclear Engineering and Construction D. Rosenblum, Manager of Nuclear Regulatory Affairs M. Merlo, Manager of Nuclear Engineering M. Short, Design Basis Document Project Manager J. Reilly, Station Technical Manager R. Ornelas, Unit 1 Licensing Manager Management Meeting Background On March 14, 1990, a Management Meeting was held in the Region V Office in Walnut Creek, California among the individuals identified in Para graph 1. The purpose of this meeting was to discuss issues related to Unit 1 design deficiencies which have been identified and reported by the licensee during the past year. One discussed in particular was the issue involving safety injection alignment delays, as discussed in Licensee Event Report (LER) 89-11, Revision 1. In addition, the licensee provided a status on engineering program improvements and the Design Basis Documentation (DBD) revie The meeting convened at 1:30. Introduction Mr. Martin opened by stating that the purpose of the meeting was to review recent technical design problems in Unit 1 and to assess the progress of engineering program initiatives since the last Management Meeting. He noted that, since the April 23, 1989 Unit 1 restart letter, a number of LERs had been issued discussing apparently significant design deficiencies. LER 89-11, "Safety Injection Alignment Delay Contrary to the Safety Analysis," was one particularly noteworthy issue concerning safety injection alignment delay problems that could potentially lead to exceeding the peak cladding temperature acceptance
criteria. As a result, there was a perception on the part of the NRC that some of the recently identified deficiencies could be more signifi cant than anticipated by the study reported in the licensee's April 23, 1989 letter. He stated that the NRC needed to understand the licensee's assessment of these problems both individually and as a whole. In addition, the potential identification of additional technical problems needed to be discussed furthe. Discussion of Identified Design Deficiencies A copy of slides used during the licensee's presentation is enclosed as an Attachment to this repor Mr. Ray began by stating that SCE had only recently tried to assess the collective significance and implications of these issue SCE has attempted to take appropriate actions on each item identified thus fa In addition, SCE has been reviewing implications for the future in light of the fact that the plant will be operating for another 3 1/2 months before the next planned outag He stated that SCE is also assessing where they expect to be at the end of the 1990 refueling outag Mr. Ray stated that SCE considered there to be eight technical issues which had been identified so fa The discussion concerning the safety injection alignment delay problem focused on the fact that the analysis discussed in LER 89-11-01 assumed the worst case scenario, based on relatively conservative assumption The assumptions on which this scenario was based included the following:
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A large loss of coolant accident (LOCA) concurrent with a loss of offsite power;
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A degraded voltage condition at 95% of full rated voltage;
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An initial reactor power of 100% (Unit 1 does not operate at greater than 92% in the reduced temperature configuration);
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A safety injection header purge in process (currently purges take place for only 30 minutes per month);
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A worst case combination of mini-flow valve delays; A three-second delay of water to the core;
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A single failure of one train of safety injection; and
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An adiabatic heatup (i.e., assuming no heat transfer to the cladding);
Taking the remoteness of all of these assumptions into consideration, the licensee considered there to be a very low probability that the peak cladding temperature acceptance criterion of 2350 degrees would be exceeded. The preliminary analysis indicated that temperature would
exceed 2300 degrees for approximately 20 seconds. In addition, the fuel cladding damage threshold of 2450 degrees (for stainless steel clad)
would definitely not be challenge Mr. Martin concluded the discussion of the safety injection alignment delay by indicating that the NRC has been reviewing all LERs, but that a collective look at these items has not been done since last year. He also indicated that, based on the licensee's discussion, it appeared that this issue was not as significant as it had appeared to be based upon initial review of the LE The remainder of the issues were discussed with significant points as identified in the enclosed slide. Program Enhancements SCE provided a status on engineering program improvements and the DBD review effort. Significant activities are identified in the enclosed slide. Closing Remarks Mr. Ray summarized by stating that none of the problems identified fall into a category of a simple system failure. Other supporting or contri buting factors are necessary for each of the problems to manifest itself in a significant failure. In retrospect, SCE considered that additional problems would be identified in Unit 1 as the enhanced engineering efforts and DBD reviews ensue, but that the significance of these items should remain relatively low. Mr. Ray also indicated that a great deal of work will be completed prior to restart from the upcoming Unit 1 outage. After the scheduled activities are completed, SCE will be able to say with high confidence that additional significant problems will not be encountere Mr. Martin stated that he considered this to have been a useful session, and indicated that he understood that SCE still plans to implement the same basic plan in light of these finding He indicated that the NRC does not want to inhibit the licensee's initiative in finding and correcting safety problems, and that the significance of the deficien cies reported in the LERs of the past year is not much different than had been anticipated. He also noted that most of the findings to date were a result of more disciplined engineering design work or because of proper questioning of nonconformance reports, design change packages, or other reviews; he acknowledged that the major thrust of the DBD reviews was just beginnin The meeting adjourned at 4:00 NRC I SCE MEETING UNIT 1 WEDNESDAY, MARCH 14, 1990 WALNUT CREEK, CALIFORNIA Southern California Edison
Overview Seven Technical Issued Have Been Identified on SONGS 1 Since Last Review Safety Significance Needs to be Gauged and Compared to Previous Expectations Appropriateness of Current Engineering Upgrade Efforts Needs to be Reassessed
SCE Approach Review Each Technical Issue
- Identify Method of Discovery
- Assess, Best Estimate, Safety Significance
- Evaluate Lessons Learned
SCE Conclusions
Most Issues Discovered by More Thorough Engineering
Overall Safety Significance
- Each Issue Individually had Negligible Safety Significance
- Two Issues Could Occur in Combination, but Nevertheless had Low Safety Significance
- Evaluation of One Issue Remains to be Completed
Engineering Upgrade Program Remains Appropriate
Background
14 Technical Issues Were Identified during Cycle 10 Refueling Outage
An Initial Assessment Reviewed 12 Issues
A Supplemental Assessment Reviewed 2 Other Issues
SCE Review Concluded that Return to Service Was Acceptable
Background (cont.)
- Supplemental Assessment of Technical Issues:
- Safety Injection Alignment Delay
- Overpressure Mitigation System Setpoint
TECHNICAL ISSUES Issue Discovery Significance
- Auxiliary Feedwater Self-revealing Negligible Actuation from Wide Range Level Instrumentation
- Valve Operator SCE review Negligible Affecting Containment Spray Flow
- Valve Single Failure SCE review Negligible Potentially Affecting Hot Leg Recirculation
- Refueling Water Storage SCE review Negligible Tank Flow Diversion
- Recirculation Boundary SCE review Negligible Spring-Loaded Check Valve
- AFW Water Hammer SCE review Negligible Requirement
- Incorrect Valve SCE review Negligible Failure Mode
Overall Conclusions DBD Effort and Major Engineering Upgrade Reviews Will Continue to Identify Technical Issues Overall Safety Significance Will Likely Be Low Engineering Upgrade Program is Effective in Increasing Thoroughness and Attention to Detail of Technical Work
FROM CV-517 RWST kLACV-518 FROM TO RECIRCULATION SPRAY PUMPS HEADER TO CHARGING PUMPS REFUELING WATER PUMPS
FCV1112 CV305 TO AU SPRAY / HOT LEG RECIRCULATION FC FC FCV1 115FMV38T FROM 5?.
COLD LEG REFUELING WNATER FCV1 I 15E MOV357 TO RCS LOOP "B F
1COLDLEG FCV 15B CHARGING PUMPS FO FCV1115D MV356 TO S
C COLD LEG FCV1 115C KAFO
SONGS 1 4RWST RECIIRC PUMP TO AUJX BULD SUMP
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RAD WASTE IX
CONTAINMENT OUTSIDE INSIDE VCT RWST VCC-317 VC318 MOV-333 M
TEST PUMP I)
.T O
REFUELING CHARGING PUMPSSPANOZE RECIRCULATION HEAT EXCHANGERl I
CONTAINMENT SUMP
H12 BLANKET RETURN CV-40A mov Iloo0C OAS
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PATH CV-"0B VCC-301 TO CHARGING PUMP SUCTION
1990 Engineering Activities Single Failure Reanalysis EQ Improvement -- F/C 1/91 Unit 1 Reload and Accident Analysis Improvements SR / NSR Boundary Valve Analysis
Instrument Air Testing lAW GL 88-14 Service Water System Review and Testing IAW GL 89-13 Electrical System Confirmatory Analysis
DESIGN BASIS DOCUMENTATION SCHEDULE 1990 System/Topical Start Finish Safety Injection 02/90A 12/90F Recirculation and Spray 01 /90A 10/90F Single Failure Topical 04/90F 06/90F Environmental Qualification Topical 06/89A 12/90F Accident Analysis Topical 12/89A 09/90F Component Cooling Water 02/90A 11/90F Salt Water Cooling 02/90A 12/90F Instrument Air and B/U Nitrogen 01 /90A 10/90F Nuclear Instrumentation System 04/90F 11 /90F Human Factors Topical 04/90F 10/90F 4kV, 480V Electrical System 04/90F 12/90F
Design Basis Documentation Lessons Learned
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Use of SCE Engineers
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16 SCE engineers in program for 1990
Verification
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Substantial resource commitment
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Verify design "as you go"
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System interfaces require special focus
Planning
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Detailed review methods
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Peer reviews have been added
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Verification of system interfaces requires a long term plan
On-going
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Walkdown program scope and criteria
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Uncertainty and margins