ML19268C173
| ML19268C173 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 11/14/1979 |
| From: | VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | |
| References | |
| NUDOCS 8001030603 | |
| Download: ML19268C173 (1) | |
Text
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Virginia Electric and Pcwer Costaany North Anna Power Station. Unit #1 EFF-4
,8 Decket Wo. 50-338 USNPC4:e 24 Hour Reportable Event 2 7 ANU ~
Written Follow-Up (supplement).
Event:
ESF Systens Returning to Mon-Safety Madd l3U lq AJl,.g3 Upen Reset of CDA Signal LER/R0 79-141/01T-0 While reviewing the operaticn of the service water systen, the casing cooling subsystem and the recirculation spray systen, it was discovered that the systems operate in a manner less censarvative than that assts ed in the accident analyses in the safety analysis report.
Following receipt of a Centairr ent Depressurization Actuaticn (CDA) signal resetting the CDA signal prior to the expiration of the tira delay relay to start the recirculttien spray punps will prchibit the function of the peps.
This is not consistant with FSAR Coccant 7.4.
Fo11cwing receipt of a Centainment Depressurizaticn Actuation (CDA) signal, resetting the CDA signal prior to the expiration of the ti:ne delay relay to start the service water radiation renitoring sanple ptmps, will prohibit the functicn of these Maps.
This is not consistent with FSAR Ccmant 7.4.
When the casing cooling gaps are startad frcus a Centairr. ant Depress-urization Actuation (CM) signal and the CDA signal is subsequently reset the purps will not restart autoratically folicwing restoration of erarger.cy pcutr asstsiing a loss of offsite pcher cccurred after CDA was reset.
This is not cenststent with FSAR response to Criterica 20 - Protection systen functicns or F5AR Cor: Dent 7.4.
khan the centrol switch for the containNnt recirculation air cooler is placed in the service water position. EV-SW110A. EV-SW110B, Ti-5V101 A and T/-5W1018 open to supply water to the ecolers.
Usen receipt of a containnent Depressurizatien Actuatien (CDA) signal taase valves close to isolate the ecolers froa service water.
TMs is required since this additional service water ficw is not used in the accident analyses.
khen the CDA signal is reset the systen returns to its non-safety rede.
This is not consistent with FSAR Corrent 7.4 The cause of these discrepar.cies are not knouri.
These discrepancias have not affected the plant and are under review by the engineering staff.
The plant is presently in a refueling shutdchn.
These events are similar to LER/R0 79-141 and will be focluded in that 14 day report.
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