ML19290C102
| ML19290C102 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/31/1979 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8001090443 | |
| Download: ML19290C102 (2) | |
Text
t lSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S street, Box 15830, Sacramento, Califomia 95813; (916) 452-3211 December 31, 1979 Director of Nuclear Reactor Regulation Attention:
Mr. Robert W. Reid, Chief Operating Reactor, Branch 4 U.S. Nuclear Regulatory Comnission Washington, D.C.
20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1
Dear Mr. Reid:
Paragraph 3.1.22(2) of the Fire Protection Safety Evaluation Report (SER) attached to License Amendment No.19, dated February 28, 1978, describes the following modif' cation for fire area 36, the ground floor main corridor.
" Reroute, apply thermal barriers over conduits, etc., to all Channel 8 cables associated with auxiliary feedwater systems, decay heat removal systems, and diesel generator."
The District requests that this paragraph be rewritten to state the following:
" Reroute circuits, insulate conduits and/or cable trays to prevent the loss of redundant equipment required for safe shutdown and cooldown."
The District is requesting the above changs since the existing paragraph requires rerouting, or installation of thermal barriers, for Channel B cables that are associated with auxiliary feedwater, decay heat or diesel generator systems that are not required for safe shutdown and cooldown. The change in wording clarifies that the intent of the modificatfor is to prevent the loss of redundant equipment required for safe shutdown and cooldown.
Paragraph 3.1 of the SER requested that
' sign details for the modification in the main corridor be submitted to the NRC for approval.
The design details are listed below. They are based on the District's requested wording for Paragraph 3.1.22(2).
Design Details for Implementing Paragraph 3.1.22(2) 1728 159 Channel B circuits, associated with the diesel generator that could fail during a design basis fire and prevent safe shutdown and cooldown, will be rerouted out of the ground floor corridor Mo(,
fire area. A fire hazard analysis has been perfonned for the 3
80010904e
/0 AN ELECTRIC SYSTEM S E RVIN G MORE THAN 600,000 IN THE HEART OF C A LI F 0 R N I A
h Mr. Robert W. Reid December 31, 1979 new fire areas the circuits are being routed through. The analysis verifies that a design basis fire in the main corridor or in the new fire areas, where the circuits are routed, will not prevent a safe shutdown and cooldown.
Circuits associated with the Channel B, decay heat removal pump, and the diesel generator supply and exhaust fan will be routed through separate conduits. This will insure that an open, short, ground or circuit interaction will not cause the loss of the required equipment.
The above modifications will insure safe shutdown and cooldown for a design basis fire in the main corridor.
Table 3.1 of the SER requires the modification described above to be completed by the end of the 1979 - 1980 refueling outage. The completion of the 1979 - 1980 refueling outage is scheduled for the first week of March, 1980.
To complete the modification when required, the District is requesting NRC comments and/or approval on the change in wording and the design criteria by February 1,1980.
Sincerely, Me ohn. Mattimoe Assistant General Manager and Chief Engineer 1728 160
.