NRC Generic Letter 89-14, Line-Item Improvements in Technical Specifications - Removal of 3.25 Limit on Extending Surveillance Intervals

From kanterella
(Redirected from NRC Generic Letter 89-14)
Jump to navigation Jump to search

text

August 21, 1989


TO: ALL LICENSEES OF OPERATING PLANTS, APPLICANTS FOR OPERATING LICENSES, AND HOLDERS OF CONSTRUCTION PERMITS

SUBJECT: LINE-ITEM IMPROVEMENTS IN TECHNICAL SPECIFICATIONS - REMOVAL OF THE 3.25 LIMIT ON EXTENDING SURVEILLANCE INTERVALS (GENERIC LETTER 89-14)

Specification 4.0.2 of the Standard Technical Specifications allows surveil-

lance intervals to be extended up to 25 percent of the time interval specified. In addition, this specification limits the combined time interval for any three consecutive surveillance intervals to less than 3.25 times the specified surveillance interval.

A lead-plant proposal was submitted by Commonwealth Edison for the LaSalle Technical Specifications (TS) to modify the 3.25 limitation on extending sur-

veillance intervals. Based on the review of the Commonwealth Edison proposal, the NRC staff concludes that the removal of the 3.25 limit from Specification 4.0.2 results in a greater benefit to safety than limiting the use of the 25-

percent allowance to extend surveillance intervals. The enclosed guidance is provided for the preparation of a license amendment request to implement this line-item improvement in TS.

Licensees and applicants are encouraged to propose changes to plant TS that are consistent with the guidance provided in the enclosure. Conforming amendment requests will be expeditiously reviewed by the NRC Project Manager for the facility. Proposed amendments that deviate from this guidance will require a longer, more detailed review. Please contact the Project Manager if you have questions on this matter.

Sincerely,

James G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation

Enclosures:

1. Guidance for the Preparation of a License Amendment Request to Remove the 3.25 Limit of Extending Surveillance Intervals
2. List of Most Recently Issued NRC Generic LettersEnclosure 1

GUIDANCE FOR THE PREPARATION OF A LICENSE AMENDMENT REQUEST TO REMOVE THE 3.25 LIMIT ON EXTENDING SURVEILLANCE INTERVALS

BACKGROUND

Specification 4.0.2 of the Standard Technical Specifications permits surveil-

lance intervals to be extended up to 25 percent of the specified interval. This extension facilitates the scheduling of surveillance activities and allows surveillances to be postponed when plant conditions are not suitable for conducting a surveillance, for example, under transient conditions or other ongoing surveillance or maintenance activities. Specification 4.0.2 also limits extending surveillances so that the combined time interval for any three consecutive surveillance intervals shall not exceed 3.25 times the specified surveillance interval. The intent of the 3.25 limit is to preclude routine use of the provision for extending a surveillance interval by 25 percent.

Commmonwealth Edison Company (CECo) submitted a lead-plant proposal for the LaSalle Technical Specifications (TS) to remove the 3.25 limit for surveil-

lances that are performed during a refueling outage and are specified with an 18-month surveillance interval. After discussions with the staff, CECo amended the proposal to remove the 3.25 limitation for all surveillances. The amended proposal was approved by the staff on a lead-plant basis. Consistent with NRC policy, this Generic Letter provides guidance for license amendment requests to implement this line-item improvement in TS.

DISCUSSION

Experience has shown that the 18-month surveillance interval, with the provi-

sion to extend it by 25 percent, is usually sufficient to accommodate normal variations in the length of a fuel cycle. However, the NRC staff has routinely granted requests for one-time exceptions to the 3.25 limit on extending refueling surveillances because the risk to safety is low in contrast to the alternative of a forced shutdown to perform these surveillances. Therefore, the 3.25 limitation on extending surveillances has not been a practical limit on the use of the 25-percent allowance for extending surveillances that are performed on a refueling outage basis.

The use of the allowance to extend surveillance intervals by 25 percent can also result in a significant safety benefit for surveillances that are performed on a routine basis during plant operation. This safety benefit is incurred when a surveillance interval is extended at a time that conditions are not suitable for performing the surveillance. Examples of this include transient plant operating conditions or conditions in which safety systems are out of service because of ongoing surveillance or maintenance activities. In such cases, the safety benefit of allowing the use of the 25-percent allowance to extend a surveillance interval would outweigh any benefit derived by limiting three consecutive surveillance intervals to the 3.25 limit. Also, there is the administrative burden associated with tracking the use of the 25-percent allowance to ensure compliance with the 3.25 limit. On the basis of these considerations, the staff concluded that removal of the 3.25 limit will have an overall positive impact on safety.

An acceptable alternative to the existing requirements of Specification 4.0.2 is the following:

.4.0.2 Each Surveillance Requirement shall be performed within the specified surveillance interval with a maximum allowable extension not to exceed 25 percent of the specified surveillance interval.

Licensees should also propose changes to update the Bases Section of Specification 4.0.2. Generic Letter 87-09 provided updated Bases for Specification 4.0.2. The following changes to the Bases of Specification 4.0.2, as provided in Generic Letter 87-09, are shown underlined to reflect this change.

Specification 4.0.2 establishes the limit for which the specified time interval for Surveillance Requirements may be extended. It permits an allowable extension of the normal surveillance interval to facilitate surveillance scheduling and consideration of plant operating conditions that may not be suitable for conducting the surveillance; e.g., transient conditions or other ongoing surveillance or maintenance activities. It also provides flexibility to accommodate the length of a fuel cycle for surveillances that are performed at each refueling outage and are spec-

ified with a 12-[an 18-]month surveillance interval. It is not intended that this provision be used repeatedly as a convenience to extend surveillance intervals beyond that specified for surveillances that are not performed during refueling outages. The limitation of Specification 4.0.2 is based on engineering judgement and the recognition that the most probable result of any particular surveillance being performed is the verification of conformance with the Surveillance Requirements. This provision is sufficient to ensure that the reliability ensured through surveillance activities is not significantly degraded beyond that obtained from the specified surveillance interval.

SUMMARY

This alternative to the requirements of Specification 4.0.2 will remove an un-

necessary restriction on extending surveillance requirements and will result in a benefit to safety when plant conditions are not conducive to the safe conduct of surveillance requirements. The removal of the 3.25 limit will provide greater flexibility in the use of the provision for extending surveillance intervals, reduce the administrative burden associated with its use, and have a positive effect on safety.

Retrieved from "https://kanterella.com/w/index.php?title=NRC_Generic_Letter_89-14,_Line-Item_Improvements_in_Technical_Specifications_-_Removal_of_3.25_Limit_on_Extending_Surveillance_Intervals&oldid=2489072"