ML20078A427
| ML20078A427 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 09/09/1983 |
| From: | Drummond F LOUISIANA POWER & LIGHT CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, W3I83-0302, W3I83-302, NUDOCS 8309230253 | |
| Download: ML20078A427 (2) | |
Text
- _ - _ _ _
7
'o a
Louisiama
,..o
< e~oe 1.e.1 P O W E R & L i G H T ! NEW OR EANS LOUSANA
. posaxsoOe 70174-0008
. (504)368-2345 MIDDLE SOUTH UTluTIES SYSTEM September 9, 1983 W3I83-0302 Q-3-A35.07
- R@ R] mew Mr. John T. Collins Regional Administrator, Region IV SEP l 6 l983 i
U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012
SUBJECT:
Waterford SES Unit No. 3 Dccket No. 50-382 Potentially Reportable Deficiency No. 120
" Static Uninterruptable Power Supply (SUPS)
Inverter By-Pass Transformer Reguliner" Final Report
REFERENCE:
Telecon from M.A. Livesay to C. Oberg dated August 11, 1983
Dear Mr. Collins:
On August 11, 1983 a problem with the Static Uninterruptable Power Supply (SUPS) Inverter By-Pass Transformer Reguliner was reported as Potentially Reportable Deficiency No. 120. The concern was that voltage spikes could be passed through the reguliner to the vital bus and subsequently to various sensitive loads, such as the reactor protective system. This letter is to inform you that after further evaluation, this condition is not considered reportable pursuant to the requirements of 10CFR50.55(e).
EVALUATION The bypass transformers sre used during maintenance to provide regulated power to the vital AC buses which feed nuclear instrumentation and other safety related loads. This PRD identified transient overvoltages on the plant distribution system which could pass through the bypass transformers with little attenuation and affect the equipment tied to the vital buses.
Since operation in bypass is restricted to one vital bus at a time, any failure or improper operation of safety related instrumentation or process control due to transients would occur on that bus only with no effect on the redundant equipment. The remaining equipment would be adequate for safe shutdown or accident mitigation.
8309230253 830909
s i
Mr. John T.-Collins W3K83-0302 September 9, 1983
. Page 2
)
Operation in the bypass mode,_as stated above, is for maintenance purposes only and represents an abnormal plant condition which is addressed in the
-Technical Spccifications. The bypass is expected to be used infrequently during plant operation with total accumulated time of only a few hours per year. The chancc of a major power system transient occurring while in the bypass mode, and this transient causing equipment damage, is sufficiently remote to be considered insignificant.
In summary, no malfunctions due to transients have been identified to date, the opportunity for damaging transients is limited and sufficient redundancy exists to maintain plant safety. For these reasons, the problem of transients from the bypass source is considered not significant under 10CFR50.55(e) and is therefore, not reportable.
Very truly yours.
f (- -,
F. J. Drummond Nuclear Services Manager cc:
1)
Director 3)
Mr. E. L. Blake Office of Inspection & Enforcement
.U. S. Nuclear Regulatory Commission Washington, D.C.
20555 2)
Director 4)
Mr. W. M. Stevenson Office of Management Information and Program Control U. S. Nuclear Regulatory Commission Washington, D.C.
20555 b