ML13319A698
Text
CO"UL 1 1 1980 Docket No.60-206 MEMORANDUM FOR:
T. M. Novak, Assistant Director for Operating Reactors, DL FROM:
L. S. Rubenstein, Assistant Director for Core and Contain ment Systems, DSI
SUBJECT:
STAFF EVALUATION OF SAN ONOFRE, UNIT 1 RE:
CONTAINMENT OVER-PRESSURIZATION POTENTIAL DUE TO AUXILIARY FEEDWATER PUMP RUN-OUT FLOW FOLLOWING A MSLB (TAC 42089)
By letter dated December 21, 1979, the staff requested Southern California Edison Company, the licensee for the San Onofre Nuclear Generating Station, Unit 1, to provide certain additional information. Specifically, the li censee was to assess the potential for containment overpressurization due to the anticipated continuous addition, at pump run-out flow, of auxiliary feed water to the affected steam generator following a postulated main steam line break (MSLB) accident.
The staff's interest in this issue.resulted from the recommendation of the Three Mile Island, Unit 2 Lessons Learned Task Force to automate initiation of the auxiliary feedwater systems. Automating the auxiliary feedwater sys tem would cause an increase in energy released to containment after a MSLB; thereby, increasing the containment pressure response to a MSLB.
By letter dated June 1980, the licensee responded to the staff's letter cited above. The containment pressure response to a MSLB inside containment was not addressed in the San Onofre Final Safety Analysis Report. The licensee has since performed such an analysis and concludes the addition of auxiliary feedwater at the nun-out flow condition results in a peak containment pres sure of 53.0 psig. The resultant containment peak pressure exceeds the de sign pressure of 51 psig.
The staff concurs with the licensee's finding that the peak containment pres sure resulting from a MSLB with the addition of auxiliary feedwater of the.
pump run-out flow rate will be 53 psig. We recommend that the evaluation of the structural response LIP the containment due to the peak containment pres sure of 53 psig be provided by the Structural Engineering Branch.
Lester S. Rubenstein, Assistant Director for Core and Containment Systems Division of Systems Integration
Enclosure:
As stated OPPICE~
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SAN ONOFRE NUCLEAR POWER PLANT, UNIT 1 TAC 42089 Docket No. 50-206 CONTAINMENT OVERPRESSURIZATION POTENTIAL DUE TO AUXILIARY FEEDWATER PUMP RUN-OUT.FLOW FOLLOWING A MAIN STEAM LINE BREAK By letter dated December 21, 1979, the staff requested Southern California Edison Company, the licensee for the San Onofre Nuclear Generating Station, Unit 1, to provide certain additional information. Specifically, the licen see was to assess the potential for containment overpressurization due to the anticipated continuous addition, at pump run-out flow, of auxiliary feed water to the affected steam generator following a postulated main steam line break (MSLB) accident.
The staff's interest in this issue resulted from the recommendation of the Three Mile Island, Unit 2 Lessons Learned Task Force to automate initiation of the auxiliary feedwater systems. Automating the auxiliary feedwater system would cause an increase in energy released to containment after a MSLB; thereby, increasing the containment pressure response to a MSLB.
By letter dated June 1980, the licensee responded to the staff's letter cited above.
The containment pressure response to a MSLB inside containment was not addressed in the San Onofre Final Safety Analysis Report. The licensee has since performed such an analysis and concludes the addition of auxiliary feedwater at the run-out flow condition (1000 gpm) results in a peak containment pressure of 53 psig. The staff concurs with the licensee's finding that the peak containment pressure re sulting from a MSLB with the addition of auxiliary feedwater at the pump run-out flow rate is 53 psig.
Enclosure