ML18057A320

Discusses Reassessment of Control Room Temp Following Station Blackout Event.Results of Analysis Indicate That Control Room Temp Will Remain Below 112 F for 4 H After Onset of Blackout

ML18057A320
Person / Time
Site:	Palisades
Issue date:	07/06/1990
From:	Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9007120360
Download: ML18057A320 (2)

Text

~roim~mrru~rn lPJ[JJ~Rner Kenneth W Berry Director POWERI Nii Nuclear Licensing MICHlliAN'S PROliRESS General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-1636 July 6, 1990 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

CONTROL ROOM TEMPERATURE FOLLOWING A STATION BLACKOUT EVENT Consumers Power Company letter dated April 17, 1989 provided Palisades response to the Station Blackout Rule (10CFR 50.63). That response was based on the application of NUMARC 87-00, "Guidelines and Technical Basis of NUMARC Initiatives Addressing Station Blackout at Light Water Reactors." Subsequently, in response to NRG Staff concerns regarding licensee implementation of NUMARC 87-00, NUMARC requested that all licensees provide the NRG with additional information regarding proper documentation and consistent implementation of the guidance provided by NUMARC 87-00.

Consumers Power Company responded to that request by letter dated March 27, 1990.

In our March 27 letter we concluded that the information provided in our original response was based on the proper use of the guidance provided by NUMARC 87-00 subject to the clarifications listed in that letter. In particular we noted that the statement made in our April 17, 1989 response that control room temperature would not exceed ll0°F during a four-hour station blackout was based on a misapplication of the NUMARC 87-00 guidance in that the analysis took credit for one non-concrete wall as a heat sink. We stated that we would reassess the transient temperature in the control room and would provide the results of the analysis prior to June 29, 1990. The results of that reassessment show that the Palisades control room will not exceed the 120°F maximum as assumed by NUMARC 87-00 section 2.7.1. The reassessment is summarized below.

The assumption of NUMARC 87-00, section 2.7.1 that the control room temperature will not exceed 120°F during a station blackout has been reassessed. This 9c)07 i2(i"::§6T:i ~ 90070~.

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2 reassessment was executed using a computer code for performing transient heat transfer calculations. The computer code uses a mathematical model of Schmidt's Graphical Method to establish the temperature versus time distributions in unsteady heat flow through the concrete boundaries of a room.

Fourier's law is used to establish heat flows at the inside and outside surfaces of the concrete. For the reanalysis conservative assumptions were made regarding the heat input to the room, the concrete surface area available as a heat sink, and the temperatures of areas adjoining the control room. The results of this analysis indicate that the control room temperature will remain below ll2°F four hours after the onset of a station blackout. The analysis did not take credit for opening doors to areas outside of the control room.

Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades