ML19343B080
| ML19343B080 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/05/1974 |
| From: | Vandenburgh D YANKEE ATOMIC ELECTRIC CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| WYR-74-48, NUDOCS 8012020654 | |
| Download: ML19343B080 (3) | |
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!dj,9, December 5, 1974 United States Atomic Energy Co =ission f" " S I s
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Washington, D.C.
20545 DEC101974 m
Attention: Directorate of Licensing
Subject:
Revised ECCS Evaluation
References:
1)
License 1:o. DPR-3 (Docket 1;o. 50-29),
2)
Proposed Change t;o. 117, " Revised ECCS Analysis",'N-.#
submitted to DOL /AEC on July 31, 1974
Dear Sir:
Pursuant to 10 CFR 50.46, a revised ECCS analysis
, performed in accordance with Appendix K, was submitted to the Directorate of Licensing on July 31, 1974. The following additional information is hereby forwarded to you as verbally requested by members of your staff on December 2, 1974.
As you already know, Westinghouse concludes that the worst single active failure during a loss-of-coolant accident (LOCA) is failure of a residual heat removal (RER) pu.p.
This is based on consideration of the effect of the failure on both energency core cooling (ECC) flow and con-tain ent heat removal capacity.
The Yankee !;uclear Power Staticn does not have power operated contain-ment cooling equipment. Thus, the worst single active failure was determined only cn the basis of its ef fect on ECC flow as su.marized below. Cceponents may be identified by referring to Figure 212.2-1 of the Final Hazards Sumary Report.
CC"PCNEI;T FAILURE CCISEQUEl:CES Valve 1:o. CS-MOV-536, Valve fails to close when 1;cne since series backups 537, 538, or 539 operator attempts closing (SI-MCV-22, 23, 24, or 25) if a break in a particular is provided.-
locp is indicated.
Valve :c. SI-MOV-1 Valvejailstocloseat Accumulator will blowdown 150 ft level of water somewhat further, however in the accumulator, relief valve operation will lower accumulator pressure.
SI-2 will prevent backficw when pressure decreases sono 20 bF9 f
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'TO:
'U.S. Atomic Energy Conmission WYR 74-48 Page Two
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December 5, 1974 l
i i
Accumulator limit Failure to operate at Parallel redundant switch switches design level will operate.
f HPSI and LPSI pumps Failure of any one of the Reduced flow, however l
pumps to start SI system is designed for diesel failure which l
is a worse case.
I Diesel Failure of any one of One LPSI and one HPSI the diesels to start pump fail to start re-sulting in reduced flow.
Safety injection valves l
still operate since they l
are powered through an auto threwover switching arrangement.
l Valve No. SI-PR-58 Regulator fails closed Parallel redundant or 59 regulator supplies required flow.
Regulator fails open Not considered an active failure since to fail I
open the diaphram must fail.
i Accumulator pilot Fails to open Parallel backup operates.
operated relief (SI-15, 16)
In conclusion, the failure of an emergency diesel to start yields the greatest reduction of ECC flew and is the worst single active failure in 1
the referenced revised ECCS analysis.
Respectfully, i
l-YANKEE ATOMIC ELECTRIC COMPANY l
Y i
i D. E. Vandenburgh Vice President dm S
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