ML19329B665
| ML19329B665 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/07/1978 |
| From: | Streeter J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Woodruff R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| NUDOCS 8002050775 | |
| Download: ML19329B665 (2) | |
Text
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4 UNITED STATES as?
f NUCLEAR REGULATORY COMMISSION REGloN til
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August 7, 1978 Docket No. 50-346 fl MEMORANDUM FOR:
R. Woodruf f, Acting Assistant Director for Technical Prograns, Office of Inspection and Enforcement G. Fiorelli, Chief, Reactor Operatians and Nuclear THRU:
Support Branch J. F. Streeter, Chief, Nuclear Support Section 1 FROM:
DAVIS-BESSE 1 - OPERATOR ACTION TO PREVENT OVERLOADING
SUBJECT:
EMERGENCY DIESEL GENERATORS DURING A LOCA FOLLOWING A LOSS OF 0FFSITE P' JER (AITS F30408H2)
During a recent inspection at Davis-Besse 1, inspectors were informed that operator action would possibly be necessary to prevent overloading the emergency diesel generators (EDG's) if a LOCA occurred after offsite power had been lost and normal shutdown equipment loads were placed on the EDG If such an event occurred with a reactor coolant system makeup bus ses.
pump (non-essential component) on an EDG bus, the operator would hav e to secure the pump within 20 seconds after initiation of the SFAS (Safety Feature Actuation System) signal to avoid EDG overload when the EDG sequencer completed its cycle. Operators at the plant have been inf ormed by the licensee of the need for the immediate action and the appropriate emergency procedure has been revised to direct the operators to immediately secure the makeup pump under these conditions.
Immediate operator action would not be necessary if the electrical system design was such that non-essential loads were automatically stripped fro 2 the emergency busses in the event a LOCA occurred subsequent to a loss of That type of automatic design feature would also avoid the offsite power.
possibility of operator error (failure to secure the makeup pumps) and attendant EDG overload during such an event. In addition, that feature would also appear to be consistent with the NRR attitude that the potential for operator misalignments of safety-related equipment immediately follow-ing design basis accidents should be minimized. However, there do not seem to be any regulatory bases for requiring such a design feature.
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August 7,1978 As stated above, Davis-Besse 1 is presently depending on immediate (less than This has been 20 seconds) operator action to avoid overloading the EDG's.
accepted by Region III as an interim measure while the licensee is pursuing a modification to provide automatic stripping of the makeup pumps in the event of an SFAS signal. In addition, Region III is pursuing this matter within Region III to determine if similar circuit designs exist at other At this time, Region III does not have information to, indicate that plants.
the design is generic.
(1) other Regions be informed of the possibility Region III recommends that of this design existing at plants within their Region, and (2) NRR be in-formed of this matter so that it can be given consideration during future licensing and rulemaking actions. Region III will advise you if future inspection results indicate a need for a Bulletin or Circular.
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J. F. Streeter, Chief Nuclear Support Section 1 cc:
G. Fiorelli R. C. Knop R. F. Warnick J. S. Creswell J. D. Smith T. N. Tambling IE Files Central Files i