ML20236Y534

SER Re Inadvertent Safety Injection During Cooldown.Typical Nozzle Could Withstand at Least Fifty Injection Events W/ Temp Differential as High as About 500 F

ML20236Y534
Person / Time
Site:	Beaver Valley
Issue date:	12/28/1979
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20236Y536	List: ML20236Y534 ML20244A913
References
IEC-78-05, IEC-78-5, TAC-10222, NUDOCS 8712140070
Download: ML20236Y534 (1)

Text

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/ g NUCLEAR REGULATORY COMMISSION l y- ,e g j E WASHING TON, D. C. 20555 7n U t9 ...; i {

f SAFETY EVA_LUAT_Ip REPORT INADVERTENT S_AFETY INJECTION DURING C00tDOWN DIVIS'ON OF OPERATING REhCT - _O?.s J<

l Inadvertent actuation of th? emergency core cooling system (ECCS) had occurred l at a number of PWR facilitics. If, at the time of inadvertent actuation, the j

reactor coolant 5,ystea (RCS) precsure is less than the ECCS discharge pressura '

arm the RCS temperature is significantly above the ECCS water temperature, theu the regions of the injection nozzles can be subjected to themal stresses.

We have performed ans?yses using conservative assumptions to obtain an upper bound for tnese stresses and conclude that a typical nc:zls could withstand l at least fifty (50) injection events with the temperature cifferentiai as l high as about 500'F. These results are consistent with tncse reported by Wes:- )

inghouse on the Salem docket. It is likely that a facility could withstand i

more than 50 inadvertent actuations of the ECCS because 1) no: all inadvertent .

ectuations will result in cold water injection inte a hot R:S, 2) if injection l does occur, the temperature differential will mout likely be less than that l assumed in our analyses, and 3) there is additional margin to failure because )

> the ASME Code limit is itself conservative.

IE Circular 78-05 dated May 23, 1978 on this subject advised facility owners of specific actions that could be taken minimizing the frecuency of inadvertent safety injections We conclude that no additional licensir.g act%n is required at this time, it would be prudent, however, for facilicy ouners to cor tinue to monitor the frequency of these events. If a particular ?i'R facility should experience more than about 25 inadvertent safety injections, then a plant specific analysis should be considered.

8712140070 PDR 7

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