ML20086R212
| ML20086R212 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 02/21/1984 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20086J894 | List: |
| References | |
| REF-GTECI-A-44, REF-GTECI-EL, TASK-A-44, TASK-OR NUDOCS 8402290004 | |
| Download: ML20086R212 (2) | |
Text
.
IM MEMORANDUM FOR:
C. J. Heltemes, Jr., Dirt w
Office for Analysis and Evaluation of Operational Data FROM:
Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
TEMPCRARY LOSS OF ALL AC POWER AT FORT ST. VRAIN We have conducted a preliminary review of AE0D's Engineering Evaluation Report No. E401 on this subject.
We share AE0D's concern renarding the undesirability of operating an onsite emergency diesel generc (EDG) in parallel with the offsite power system when the offsite system is experiencing problems.
Although a licensee may enter into such operation in an honest attempt to irprove the safety posture of the plant, such parallel operation may in fact create a net reduction in safety, Not only is the EDG exposed to external electrical transients that could interrupt operation of the EDG, but also it is not clear that either the loss-of-offsite-power loads sequencer (for safe shutdown) or the accident loads sequencer will function properly if the initial condition is that the EDG output breaker has already been closed for several minutes. The lack of a clear Technical Specification restriction on such parallel operation may have contributed to this event. The inadequacy of the EDG testing procedure at Fort St. Vrain may be indicative of testing against only the licensing basis worst-case scenario, to the exclusion of other scenarios, such as the one illustrated by the Fort St. Vrain operating event.
The Division of Licensing is evaluating these concerns to determine what short term actions, if any, is appropriate. Because of the technical complexities involved, this evaluation is not yet complete. We will continue to work with your staff as our review proceeds.
With regard to longer term actions, these concerns'will be addressed in the Regulatory Guide being developed as part of the proposed resolution of USI A-44, " Station Blackout".
Cri$ul SWei k7
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'MEM0rANQUM FOR:
C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data FROM:
Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
\\
TEMPORARY LOSS OF ALL AC POWER AT FORT ST. VRAIN
\\
We have conducted a preliminary review of AE0D's Engineering Evaluation Report No. E401 on this subject. WE share AE0D's concern regarding the undesirability 4
of operating an onsite emergency diesel generator (EDG) in parallel with the offsite power system when the offsite system is experiencing problems.
u Although a licensee mdy enter into such operation in an honest attempt to improve the safety posture-of the plant, such parallel operation may in fact create a net reduction in safety. Not only.is the EDG exposed to external electrical transients tha't could interrupt operation of the EDG, but also it is not clear that either the loss-of-offsite-power loads sequencer (for safe shutdown) or the accident lbads sequencer will # unction properly if the initial condition is that the.EDG output breaker has already been closed for several minutes. The lack of'a clear Technical Specification restriction on such parallel operation may have contributed to this event. The inadequacy of the EDG testing procedure at Fort St. Vrain may be indicative of testing against only the licensing basis' worst-case scenario, to the exclusion of other scenerios, such as the one illustrated by the Fort St. Vrain operating event.
\\
The Divisi n of Licensing is evaluating these EDG concerns to determine what short tern action, if any, is appropriate.
Because of the technical complexities involved, this evaluation is not yet c' plete. We will continue to work with your staff as our review proceeds.
Q To address the need for longer term actions, the Division of Safety Technology will prioritize these EDG concerns, in accordance with established NRR procedures.
We are also considering the need to have licensees address these ccncerns as part of the required licensee followup actions ' hich are included under the w
current proposed iesolution of A-44, " Station B1hckout."
\\
Harold R. De ton, Director Office of Nuclbar Reactor Regulation N
Contact:
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