Surveillance Intervals in Standard Technical Specifications (Generic Letter No. 83-27)
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
July 6, 1983
TO ALL LICENSEES AND APPLICANTS FOR OPERATING POWER REACTORS AND HOLDERS OF
CONSTRUCTION PERMITS FOR POWER REACTORS
Subject: Surveillance Intervals in Standard Technical Specifications
(Generic Letter No. 83-27)
There appears to be a misunderstanding as to the basis for the surveillance
intervals given in the Standard Technical Specifications (STS) and in some
existing custom Technical Specifications in use by a number of licensees.
We have received several requests recently from licensees converting to
18-month fuel cycles to increase the surveillance intervals for the 12-month
and 18-month surveillance requirements in plant-specific Technical
Specifications. The requests indicated that the increase in surveillance
intervals would maintain the same contingency period beyond nominal fuel
cycle periods that existed in their approved Technical Specifications for
shorter fuel cycles. The nominal surveillance interval was not established
to provide a fixed contingency period beyond nominal fuel cycle periods.
The purpose of this letter is to reiterate the bases for the specified
surveillance intervals and to advise licensees of our current practice with
respect to requests to increase surveillance intervals.
The 18-month surveillance intervals contained in the STS were established
during the original development of STS after consultations with various
senior staff members and with the reactor and fuel vendors. The 18-month
surveillance intervals were established based upon operating experience and
the knowledge that some reactors would be utilizing 18-month fuel cycles.
To provide the necessary operational flexibility which may be required due
to scheduling and performance considerations, the STS, and most custom
Technical Specifications, include a provision which permits any surveillance
interval to be extended by 25% of the nominal interval provided that the
total time interval does not exceed 3.25 times the specified surveillance
interval over any three consecutive surveillance intervals.
The effect of extended outages was also considered during our development
and establishment of the 18-month surveillance interval. We presumed that
if a plant incurs an extended outage during a fuel cycle, the licensee would
perform the appropriate surveillances during the extended outage so that
required surveillances will not become due before completion of the fuel
The 12-month surveillance intervals applicable to certain portions of the
fire protection (fire water systems) Technical Specifications were based
upon annual climatic conditions rather than on the length of a fuel cycle;
therefore, these intervals should not be changed. As stated in the STS
Bases for the snubbers, establishment of the snubber surveillance intervals
was based upon maintaining a constant level of protection. The assumptions
used for maintaining the constant level of protection would be invalidated
if the surveillance intervals are changed.
We intend to retain the 18-month and 12-month surveillance intervals given
in the STS and plant-specific Technical Specifications except that
infrequent, one time only changes may be granted for plant-specific
conditions where adequate justification is given.
Darrell G. Eisenhut, Director
Division of Licensing
Page Last Reviewed/Updated Thursday, March 25, 2021