ML20216B805

Suppl to 870603 Application for Amend to License NPF-29, Providing Addl Info on Significant Hazards Consideration Re Reduction of Snubber Sample Size After Test Failure from 10% to 5% for Sample Plan 1

ML20216B805
Person / Time
Site:	Grand Gulf
Issue date:	06/22/1987
From:	SYSTEM ENERGY RESOURCES, INC.
To:	NRC COMMISSION (OCM)
Shared Package
ML20216B736	List: AECM-87-0122, Forwards Suppl to 870603 Application for Amend to License NPF-29,revising Tech Spec to Reduce Snubber Sample Size After Test Failure from 10% to 5% for Sample Plan 1 of Surveillance Requirement 4.7.4.e ML20216B805
References
TAC-65511, NUDOCS 8706300157
Download: ML20216B805 (4)

Text

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BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION;-

LICENSE N0. NPF-29 .

DOCKET N0. 50-416 IN.THE MATTER OF- 1 MISSISSIPPI POWER & LIGHT COMPANY and SYSTEM ENERGY RESOURCES, INC'.

and SOUTH MISSISSIPPI ELECTRIC POWER ASSOCIATION y 1

1 AFFIRMATION I, 0. D. Kingsley, Jr., being duly sworn, stated.that I am Vice ..

President, Nuclear Operations of System Energy Resources, Inc.'; that on behalf-of System Energy Resources, Inc., and South Mississippi: Electric Power Association I am authorized by System Energy-Resources,.Inc. to sign and file with the Nuclear-Regulatory Commission, this-application for amendment of the- ,

Operating License of the Grand Gulf Nuclear Station; that. I: signed.this

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l application as-Vice President, Nuclear Operations of System Energy Resources,- 4 Inc.; and that the statements made and the matters set for h herein are true and correct to the best of my knowledge, information and ef.

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STATE 0'F MISSISSIPPI COUNTY OF HINDS l

SUBSCRIBED AND SWORN T0 before me, a'NptAry Public, in and.for the County'and State above named, this f @ ay of ( &# _-1987.-

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(SEAL)'.

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. Notary Public' My commission expiresi  ;

My Commbsbn Expkes Sep. 21,1037 l 8706300157 870622 PDR ADOCK 05000416' P PDR J16AECM87061701. .4 ,

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SIGNIFICANT HAZARDS CONSIDERATION ADDITIONAL INFORMATION ON SNUBBER SAMPLE SIZE

1. The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated. All snubbers (except those on nonsafety-related systems per Specification 3.7.4) are required to be operable in Operational Conditions 1, 2, and 3; and, in Operational Conditions 4 and 5 for snubbers located on systems required operable in those operational conditions. Operability of these snubbers helps to ensure that the structural integrity of the reactor coolant system and all other safety-related systems is maintained I during and following a seismic or other event initiating dynarric loads. In order to ensure operability of these '.

snubbers, surveillance tests are performed using visual inspections and functional tests. The visual inspection frequency is based on maintaining a constant level of snubber protection and is not affected by this proposed technical specification change. To provide assurance of snubber functional reliability, three sample plans are presently provided in Specification 3.7.4 as follows:

1. Functionally test 10% of a type of snubber with an additional 10% tested for each functional testing failure, or

2. Functionally test a sample size and determine sample acceptance or rejection using Technical Specification Figure. 4.7.4-1, or

3. Functionally test a representative sample size and determine sample acceptance or rejection using the equation stated in Specification 3.7.4.

The proposed change affects sample plan 1 by changing the additional 10% test criteria to 5%. This 10% additional test criteria was accepted by the NRC in the absence of a suitable snubber failure data base (Reference NRC letter regarding Operating License DPR-49 for Iowa Electric Light and Power Company dated March 12,1985). Subsequently, the ASME OM-4 group developed a sampling. plan which requires only 50% of the initial sample size need be tested for each failed snubber. As stated in the ASME OM-4 standard, during its development considerable emphasis was placed on the accumulation of equipment dynamic restraint performance data by examination or testing throughout the operational life of the device. 'This data will be periodically' reviewed by the OM-4 Working Group. This summation of data-will provide a statistical basis for determining performance.of J16TS87060901'- 1

L equipment dynamic restraints inservice and', in turn, will

' allow for the reevaluation of the test frequency requirements established by'the OM-4 Standard.- The OM-4 Standard was approved by the American Society of Mechanical Engineers Committee on Operation and Maintenance of Nuclear. Power Plant Components and the American National Standards-

' Institute.

The ability of the snubbers to perform their design function has not been decreased by this proposed change.

Snubbers are dynamic restraints that help to mitigate the consequences of a seismic event or other dynamic loading event and as such do not increase the probability of occurrence of any accident previously evaluated. This change does not involve a significant increase in the -

{ consequences of an accident previously evaluated because-the proposed additional testing' criteria. of 5% for sample plan 1 is based on snubber failure rate data and will provide adequate detection capability for additional snubber failures. The ability.to detect' snubber. failures ensures that dynamic' restraints are functional and'that the consequences of an accident.will.not'be significantly increased.

The proposed change does not create' the possibility of-a 2.

new or different kind of accident from any previously analyzed. The accidents potentially affected by the proposed change involve seismic or other' events initiating dynamic loads on the reactor coolant system and other safety-related systems. Snubber visual inspections and functional testing using sample plans 2 and 3 of Specification 3.7.4 are not affected by the. proposed .

change. The initial sample size of 10% of the total of- )

each type of snubber per sample plan 1 of Specification 3.7.4 is also not-affected by the proposed. change. The, '

change from 10% to 5% for additional testing after a test failure in sample plan l'is based on snubber failure data <

as evaluated by the ASME OM-4 group. .

This change does not significantly affect the ability.to detect snubber failures; therefore, there is no possibility of. a new or.~ 1 different kind of accident from any previously analyzed. l 1

3. The proposed change does not involve a significant- I reduction in a margin of safety. The proposed change is based on snubber failure data as-evaluated by the ASME  :

0M-4 group and will provide adequate assurance that i' snubber failures will be detected. Since snubber failures.

will adequately be detected by the proposed. testing 1 criteria change, assurance is>provided-such that seismic 1 or other events initiating dynamic loads on the reactor coolant system or other safety-related systems will not: -l adversely affect their structural integrity. . Sample-plan 3 of Specification'3.7.4 presently requires that an

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1 additional 50% of the initial sample size be tested for ,

each snubber type'which does not meet the functional test ]

acceptance criteria. The proposed change to sample plan 1  !

will implement similar additional testing criteria as  ;

presently contained in-sample. plan 3. Therefore, the proposed change does not involve a significant reduction in a margin of safety.

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