NRC Generic Letter 84-15, Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability
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July 2, 1984
TO ALL LICENSEES OF OPERATING REACTORS, APPLICANTS FOR AN OPERATING LICENSE, AND HOLDERS OF CONSTRUCTION PERMITS
Gentlemen:
SUBJECT: PROPOSED STAFF ACTIONS TO IMPROVE AND MAINTAIN DIESEL GENERATOR RELIABILITY (Generic Letter 84-15)
As part of the proposed technical evaluation of Unresolved Safety Issue (US-I) A-44, Station Blackout, the staff is considering new requirements that would reduce the risk of core damage from station blackout events. The reliability of diesel generators has been identified as being one of the main factors affecting the risk from station blackout. Thus, attaining and maintaining high reliability of diesel generators is a necessary input to the resolution of USI A-44.
Plants licensed since 1978 have been required to meet the reliability goals of Regulatory Guide 1.108 for their diesel generators. However, the staff has determined that many operating plants do not have reliability goals in place for their diesel generators. Considering the critical role diesel generators play in mitigating various transients and postulated events following a loss of offsite power, the staff has determined that there is an important need to assure that the reliability of diesel generators at operating plants is maintained at an acceptable level. The staff has determined that the risk from station blackout is such that early actions to improve diesel generator reliability would have a significant safety benefit. Toward this objective, we hove developed the following approach to assess and enhance, where necessary, the reliability of diesel generators at all operating plants.
The items covered by this letter fall into the following three areas:
- 1. Reduction in Number of Cold Fast Start Surveillance Tests for Diesel Generators
This item is directed towards reducing the number of cold fast start surveillance tests for diesel generators which the staff has determined results in premature diesel engine degradation. The details relating to this subject are provided in Enclosure 1. Licensees are requested to describe their current programs to avoid cold fast start surveillance testing or their intended actions to reduce cold fast start surveillance testing for diesel generators.
- 2. Diesel Generator Reliability Data
This item requests licensees to furnish the current reliability of each diesel generator at their plant(s), based on surveillance test data. Licensees are requested to provide the information requested in Enclosure 2.3. Diesel Generator Reliability
Licensees are requested to describe their program, if any, for attaining and maintaining a reliability goal for their diesel generators. An example of a performance Technical Specification to support a desired diesel generator reliability goal has been provided by the staff in Enclosure 3. Licensees are requested to comment on, and compare their existing programs or any proposed program with, the example performance specification.
Accordingly, pursuant to 10 CFR 50.54(f), operating reactor licensees are requested to furnish, under oath or affirmation, no later than 90 days from the date of this letter, the information requested in Items 1 through 3 above. Applicants for operating licenses and holders of construction permits are not required to respond.
Licensees may request an extension of time for submittals of the required Information, Such a request must set forth a proposed schedule and justification for the delay. Such a request shall be directed to the Director, Division of Licensing, NRR. Any such request must be submitted no later than 45 days from the date of this letter.
This request for information has been approved by the Office of Management and Budget under Clearance Number 3150-0011, which expires April 30, 1985.
Sincerely,
Darrell G. Eisenhut, Director Division of Licensing
Enclosures:
- 1. Reduction in Number of Cold Fast Starts for Diesel Generators
- 2. Diesel Generator Reliability Data
- 3. Diesel Generator Reliability
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