Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
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.
8407020206
.
- 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
.
