ML13310A815
| ML13310A815 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/24/1983 |
| From: | Baskin K Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-09-05, TASK-9-5, TASK-RR NUDOCS 8306290415 | |
| Download: ML13310A815 (2) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGER OF NUCLEAR ENGINEERING, (213) 572-1401 SAFETY, ANG LICENSING June 24, 1983 Director, Office of Nuclear Reactor Regulation Attention: D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Divi-sion of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 SEP Topic IX-5, Ventilation Systems San Onofre Nuclear Generating Station Unit 1 By letter dated December 16, 1981, we provided you with our draft safety assessment for the subject topic. In our assessment we indicated that additional study was being done on the charging pump room, 480 V and 4160 V switchgear rooms and the battery and inverter rooms housed in the Administration Building. Your evaluation, dated November 2, 1982 confirmed the need for additional study of these areas.
Since the submittal of our earlier evaluation of the need for cooling in the 4160V and 480V rooms, several fire protection program modifications have been implemented which affect these rooms. These modifications include fire dampers and cable tray foam which act to isolate the rooms and eliminate any natural circulation of external air. Since it has
-been det-ermi-ned-t-hat--operation-.of-th-is equipment, withLexcess.ive room ambi ent temperature involves -potential increase in the loss of equipment capabilities and life, external cooling is being provided. New ventilation systems are being provided for the 4160V and 480V rooms. Each room will have its own system consisting of an air conditioning unit with backup supply and exhaust fans. These systems are designed to maintain the rooms at temperatures below 104 0F during normal operation. The air conditioning units and supply and exhaust fans are being installed as non-safety related quality class. Should the units fail following a postulated accident, the switchgear loads would be less than during normal operation and therefore heat removal from these rooms would not be expected to be critical.
However, prior to startup from the current outage, an analysis of the potential temperature profile for these rooms will be performed to confirm that post accident cooling will not be necessary.
A03r 8306290415 830624 PDR ADOCK 05000206 P
Mr. D.
June 24, 1983 As noted in our December 16, 1981 submittal, the supply fan to the charging pump room is supplemented by the containment sphere purge and exhaust air handling units. These two units are each substantially larger than the single air supply unit in the charging pump room. Our evaluation of the failure of the single supply fan indicates that no ventilation problems will occur as the larger air exhaust fans are sufficient to maintain adequate ventilation.
We have completed our evaluation of the effects of losing the Control Building HVAC on DC Switchgear and Inverter room and battery room ventilation. Loss of the HVAC will not adversely affect the battery room due to the relatively small amount of heat expected to be generated by the batteries and their high heat capacity. An existing vent in the battery room roof provides assurance that hydrogen buildup would not be a problem. An undetected loss of the HVAC in the DC switchgear and inverter room could lead to excessive room temperature due to the inverters heat load. The need for additional ventilation in this room will be addressed during the Integrated Assessment.
If you have any questions in this matter, please contact me.
Very truly yours,