ML13330B432
| ML13330B432 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/23/1988 |
| From: | Nandy F Southern California Edison Co |
| To: | NRC Office of Administration & Resources Management (ARM) |
| References | |
| NUDOCS 8811290085 | |
| Download: ML13330B432 (2) | |
Text
0.0 Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 F. R. NANDY TELEPHONE MANAGER OF NUCLEAR LICENSING (818) 302-1896 November 23, 1988 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington,:D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Nuclear Instrumentation System Upgrade San Onofre Nuclear Generating Station Unit 1 In response to a telephone request from Mr. Charles Trammell on November 23, 1988, we are enclosing for your review additional information regarding the impact on AC/DC System capacity and capability resulting from the Nuclear Instrumentation System upgrade. The additional information has been incorporated into the response to Question 2 of the enclosure to our letter dated November 10, 1988.
If you have any questions regarding this, please contact me.
Very truly you Enclosure cc: C. M. Trammell, NRR Project Manager, San Onofre Unit 1
- 3. B. Martin, Regional Administrator, NRC Region V F. R. Huey, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 11290085 88112 FIDR ADiOCK 05000206, PDIC
ADDITIONAL INFORMATION FOR RESPONSE TO QUESTION NO. 2 SONGS 1 NUCLEAR INSTRUMENTATION SYSTEM UPGRADE
- 2. In support of the replacement upgrade of the Nuclear Instrumentation System (NIS), as indicated by letter dated April 15, 1988, the upgrade of the NIS will increase the DC system load. As a consequence of this increased load, the margin of safety for DC system capacity and capability will be reduced. The significant hazards consideration analysis (which states that the revision to the battery test acceptance criterion from 80 to 85 percent will ensure that an existing safety margin is maintained) does not adequately address reduced margin of safety for DC system capacity and capability due to increased load.
For each component part of the DC system (battery, charger, and distribution system components) that will be required to supply the increased load, provide the results of your analysis which demonstrates that the DC system can adequately accommodate the increased load.
RESPONSE
The additional NIS loads (net) on Regulated Bus #1 (RB #1)
(8-11R3), RB #2 (8-12R3), RB #3 (8-13R3), and RB #4 (8-14R3) are 3.8, 3.9, 0.37 and 5.46 amps, respectively. To accommodate these additional loads, the existing 5-amp fuses on 8-11R3, 8-12R3 and 8-14R3 will be replaced as part of the NIS design change with appropriately sized fuses. The 5-amp fuse on 8-13R3 is adequate for the additional loads; however, it is being replaced along with the other fuses.
The impact of these additional NIS loads on the Maintained 120V AC distribution system components and the 125V DC distribution system components, from the NIS cabinets up to and including the battery, battery charge, battery charger input breakers, and the alternate supply breaker at MCC 2, was further evaluated for bus capacity, proper fuse/breaker sizing/coordination, component/cable ratings, system voltages, NIS cabinet input voltages, and short circuit capabilities. Each component has been found to be adequate to provide for the increased load requirements.