ML20034A991
| ML20034A991 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 04/16/1990 |
| From: | Terry C NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NMP1L-0491, NMP1L-491, NUDOCS 9004250188 | |
| Download: ML20034A991 (2) | |
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NMM NIAGARA MOHAWK POWER CORPORATION!301 PLAINFIELD ROAD. SYRACUSE N Y._13212/ TELEPHONE (315)4741511 April 16, 1990
-NMPIL 0491 t
U.S. Nuclear Regulatory rommission Attn: Document Control Desk Hashington, D.C. 20555 Re:
Nine Mile Point Unit 1 Docket No. 50-220 DPR-63 Gentlemen:
Our letter of April 13, 1989 (NMPIL 0384)'provided an assessment of Nine' Mile Point Unit l's ability to withstand and recover from a station blackout (SBO) in accordance with-the requirements of 10CFR50.63.
Included within this assessment was an evaluation of the 125 VDC Class llE batteries ability to meet SB0 loads, for the'SB0 duration of four hours
- The results of our evaluation indicated that the_125 VDC Class lE batteries were inadequate to meet the required SB0 loads.
However, we stated that'an: analysis was being performed of station battery loads to determine if additional load' stripping-will' allow-Nine Mile Point Unit I to meet SB0 loads for four hours or whether additional; capacity is required.
This letter provides the'results'of our analysis.
Since the completion of our-original evaluation, we have installed two (2) new Class IE' station batteries that are significantly larger than the original batteries (2320 Ampere Hour vs.1500 Ampere Hour nominal rating).
Additionally, Special Operating Procedure No. N1-SOP-18,~ " Station Blackout",
has been issued to include battery load shedding and initiation of 125:VDC System restoration in the event.of a loss of offsite power with -failure of both emergency diesel generators.
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PDR ADOCK 03000220
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- As a result of the above changes,'our reanalysis now indicates that 125 VDC Class 1E batteries No. 11 and 12 are adequate to meet the required SB0 loads-for the four hour coping duration, with no operator action assumed for the first 30 minutes. According to procedure N1-SOP-18 however, DC load shedding-is accomplished within 15 minutes after the initiation of a station blackout.
The fifteen minute time period is consistent with operator action response times required to meet the Appendix R Analysis for Nine Mile Point Unit 1.
Very truly yours, NIAGARA H0 HANK P ER CORPORATION C.-D. Te Vice President i
Nuclear _ Engineering and Licensing DJH/sek 2104b xt: Regional Administrator, Region I
-j Mr. R. A. Capra, Director
.j Mr. 9. E. Martin, Project Manager i
Mr. W. A. Cock, Resident Inspector i
Records Management 1
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