ML17279A658

Application for Amend to License NPF-21,modifying Snubber Functional Testing Sampling Plans,Per Guidelines of Draft Ansi/Asme - OM-4 Document, Exam & Performance Testing of Nuclear Power Plant Dynamic Restraints. Fee Paid

ML17279A658
Person / Time
Site:	Columbia
Issue date:	12/01/1987
From:	Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML17279A659	List: ML17279A658 ML17279A660
References
GO2-87-278, TAC-88808, NUDOCS 8712080152
Download: ML17279A658 (13)

Text

REGULA INFORMATION DISTRIHUTIO YSTEM (RIDB)

ACCESSION NHR: 8712080152 DOC. DATE: 87/12/01 NOTARIZED: YES DOCKET ¹ FAC IL: 50-397 WPPSS Nuclear Pro Jecti Unit 2 Washington Public Powe 05000397

.AUTH. NAME AUTHOR AFFILIATION BOB ENBEN z G. C. Washington Public Power Supply System RECIP. NAME RECIPIENT AFFILIATION Document Conte ol Hl anch (Document Control Desk)

SUBJECT:

Application for amend to License NPF-21'odifying snubber functional testing sampling plans'er guidelines of draft ANSI/ABME OM-4 documents "Exam Zc Performance Testing of Nuclear Power Plant Dynamic Restraints." Fee paid.

DISTRIBUTION CODE: AOOID COPIEB RECEIVED: LTR TITL'E: OR Submittal: General Distribution i ENCL i SIZE: 7 NOTES:

RECIPIENT COPIES REC IP IENT COPIEB ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 0 PD5 PD 5 5 SAMWORTHI R 1 1 INTERNAL'CRB 6 6 ARM/DAF/LFMH 0 NRR/DEBT/ADS 1 1 NRR/DEBT/CEH 1 1 NRR/DEBT/MTH 1 NRR/DEBT/RSH 1 NRR/DOEA/TSH 1 1 NRR/P 8/ILRH 1 1 OQC/HDB2 1 0 ILE 01 1 1 REB/DE/EI 8 1 1 EXTERNAL'PDR 1 1 ,NRC PDR NBIC 1 TOTAL NUMBER OF COP IEB REQUIRED: LTTR 26 ENCL 23

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Washington Public Power Supply System 3000 George Washington Way P.O. Box 968 Richland, Washington 99352-0968 (509)372-5000 December 1, 1987 G02-87-278 Docket No. 50-397 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

NUCLEAR PLANT NO. 2

'PERATING LICENSE NPF-21 REQUEST FOR AMENDMENT TO TECHNICAL SPECIFICATION 3/4.7.4 (SNUBBERS)

In accordance with the Code of Federal Regulations Title 10, Parts 50.90 and 2. 101, the Supply System hereby requests an amendment to the NNP-2 Technical Specification. Specifically, the Supply System is seeking to modify snubber functional testing sampling plans as detailed in Technical Specification 4.7.4.e per the guidelines of the draft ANSI/ASME ON-4 document (Examination and Performance Testing of Nuclear Power Plant Dynamic Restraints), see Attachment 2.

The first of three approved sampling plans, the "10 percent plan", des-cribed in Specification 4.7.4.e(1) requires 10K of the snubbers to be tested periodically. It requires testing of an additional 105 of the snubbers for each snubber not meeting the acceptance criteria of Specifi-cation 4.7.4.f. The proposed change modifies this plan to require only a 5X additional testing for each snubber that fails functional testing as opposed to 10K additional testing presently required. Reducing the per-centage of snubbers to be retested does not undermine the effectiveness of this surveillance. The initial test sample remains the same and is suffi-cient to provide an adequate sampling of the snubbers. This change will reduce the amount of additional testing required and thus reduce man-rem exposure and safety concerns associated with unnecessary functional testing. This change is consistent with the ASNE OM-4 document.

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Page Two RE()UEST FOR AMENDMENT TO TS 3/4.7.4 (SNUBBERS)

The second sampling plan, the "37 plan", described in Specification 4.7.4.e(2) requires that a representative sample of .snubbers be tested periodically in accordance with Figure 4.7-1. Figure 4.7-1 provides the acceptance criteria method for the functional test results and denotes a "reject" region and a "continue testing" region. If at any time the plotted test results fall within this "reject" region, then all snubbers are to be functionally tested. The proposed change revises surveillance requirement 4.7.4.e(2) and Figure 4.7-1 to delete the "reject" region and substitute an expanded "continue testing" region. With the deletion of the "reject" line plotting of results by lot or individual basis becomes a moot point because snubbers must continue to be tested until the point falls into the "accept" region or until all snubbers have been tested.

The proposed change also deletes references to the "reject" region in th' text of Specification 4.7.4.e(2) and bases 3/4.7.4. Bases 3/4.7.4 is also being supplemented by a footnote such that if testing continues to be between 100 200 snubbers and the accept region has not been attained, then the actual percent of population quality (C/N)* would be used to indicate the probability of extended or 100 per cent testing. A population quality of greater than or equal to 5% failed snubbers will probably result in extended testing.

Figure 4.7-1 as it appears in the Technical Specification was developed using "Hald's Sequential Probability Ratio Plan". Statistical studies using Hald's sequential sampling plan indicate that a major change in the reject line caused an insignificant change in the accept line or in other words acceptance is independent of rejection. These studies also demon-strate that while the probability of false acceptance of a bad snubber population under the proposed amendment still exists it is negligible. As long as the "reject" line remains in the sample plan there is some possi-bility of rejecting a good snubber population and consequently requiring an unnecessary 100$ functional testing of snubbers with attendant ALARA and safety concerns, manpower util,ization and outage extension. The proposed technical specification change will alleviate these problems and still ensure continued or additional testing if snubber, quality of failed snubbers is equal to or greater than SX. These changes have been pre-viously evaluated by the NRC through ANSI/ASME OM-4 participation and by granting similar technical specification, changes.

References:

Duke Power Company NcGuire Nuclear Stations.

• Number of 'snubbers not meeting the acceptance criteria "C"/number of snubbers tested "N".

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Page Three REQUEST FOR AMENDMENT TO TS 3/4.7.4 (SNUBBERS)

The third sampling plan, the "55 plan", described in Specification 4.7.4.e(3) also requires that a representative sample of snubbers be periodically tested. Deleting the "reject" line from the "37 plan" makes the "55 plan" unnecessary. Moreover the "55 plan" is not a Wald sequential plan and as such has been deleted from the ASNI/ASME ON-4 draft document.

The proposed change clarifies additional functional testing requirements due to failure of snubbers. Technical Specification 4.7.4.e states that if during the functional testing, additional sampling is required due to failure of only, one'ype of snubber, the functional test results shall be reviewed at that time to determine if additional samples should be limited to the type of snubber which has failed the functional testing. The pro-posed change allows categorization of unacceptable snubbers into failure mode groups. A test failure mode group shall include all unacceptable snubbers that have a given failure mode and all other snubbers subject to the same failure mode. It allows independent testing of failure mode groups based on the number of unacceptable snubbers and requires one additional test sample from the general population for each failure mode group to provide assurance that failure mode groups have been properly established. This change is consistent with the ASME OM-4 document." A flow chart (Attachment 1) shows how Snubber Functional Testing shall be carried out at WNP-2. This flow chart shall be included in the implementing procedures.

The proposed change also addresses the functional test failure analysis of locked up snubbers. Technical Specification 4.7.4.g states that if the cause of the locked up snubbers is due to manufacturer or design deficiency, all snubbers of the same type subject to the same defect shall be functionally tested. The proposed change includes unexpected transient events as a cause of locked up snubbers in addition to manufacturer or design deficiency and changes the requirement of mandatory functional testing of this type of failure mode group snubbers to evaluation in a manner (stroking, testing, replacement etc.) to ensure their operability.

For mechanical snubbers, this evaluation of oper ability can easily be demonstrated by determining the freedom of motion by stroking the snubbers rather than functional testing. This will provide better manpower utilization, reduce man-rem exposure and safety concerns associated with unnecessary functional testing. "

All locked snubbers shall be replaced or repaired to original qualified condition. This change to evaluation i'n a manner to ensure operability rather than mandatory functional testing has previously been reviewed and approved on the McGuire Nuclear Stations.

The Supply System has reviewed this request per 10CFR 50.59 and 50.92 and has determined that no unreviewed safety questions or significant hazards will result relative to the proposed change based on the following considerations:

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Page Four REQUEST FOR AMENDMENT TO TS 3/4.7.4 (SNUBBERS)

Do the proposed changes involve a significant increase in the proba-bility or consequences of an accident previously evaluated?

No. reducing the percentage of additional snubbers to be tested from 10K to 5% for "10 percent plan" does not undermine the effectiveness of this surveillance. The initial test remains the same and is suffi-cient to provide an adequate sampling of the snubbers. This change reduces the amount of additional testing without affecting the pre-viously established confidence level.

Deleting the "reject" line from the "37 plan" does not affect accep-tance of the snubber population because snubbers must continue to be tested until the acceptance criteria are met or until all snubbers have been tested. Deletion of the "reject" line from the "37 plan" also makes the "55 plan" unnecessary. Statistical studies indicate that these changes do not reduce the previously established confidence level and thus have no affect on the structural integrity of the reactor coolant system and other safety related systems under dynamic loading. Hence the probability or consequences of previously evaluated accidents are not significantly increased.

2) Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

No, because the proposed changes involve no changes to system design bases or system function and do not introduce any new variables beyond those previously considered.

3) veillancee Do the proposed changes involve a significant reduction in the margin of safety?

Although the proposed amendments do not involve changes in sur-frequency or operating conditions, they do involve changes in surveillance methods and sample size but not individual acceptance criteria. However, statistical evidence indicates that while the probability of acceptance of a bad snubber population under the pro-amendments still exists, it does not represent a significant 'osed reduction to the margin of safety.

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Page Five RE(UEST FOR AMENDMENT TO TS 3/4/7.4 (SNUBBERS)

As discussed above the Supply System considers that this change does not involve a significant hazards consideration nor does it involve a signi-ficant change in the types or significant increase in the amount of any effluents that may be released offsite, nor does it involve a significant increase in individual or cummulative occupational radiation exposur e. In actuality it will allow reduction or avoidance of increased radiation the'roposed change meets the eligibility criteria exposure. Accordingly, for categorical exclusion set forth in 10CFR 51.22(c)(9) and therefore per 10CFR 51.22(b) an environmental assessment of the change is not required.

The Supply System requests that this technical specification amendment be approved prior to our next scheduled refueling outage, presently scheduled to begin no earlier than March 15, 1988. For this reason, we have sub-mitted it in advance of, 'the outage in order to allow the staff and the Supply System sufficient time for processing.

This change has been reviewed and approved by the WNP-2 Plant Operations Committee and the Supply System Corporate Nuclear Safety Review Board.

In accordance with 10CFR 170.21, an application fee of one hundred fifty dollars ($ 150.00) accompanies this request. In accordance with 10CFR 50.91, the State of Washington has been provided a copy of this letter.

Should you have any questions, please contact Mr. P. L. Powell, Manager, WNP-2 Licensing.

Yery truly yours, G. C. orensen, Manager Regu atory Programs PLP/bI<

Attachments cc: C Eschels EFSEC JB Hartin - NRC RV NS Reynolds BCPER .

RB Samworth - NRC DL Williams BPA NRC Site Inspector 901A

STATE OF WASHINGTON )

Subject:

)

COUNTY OF BENTON )

I, G. C. SORENSEN, being dully sworn, subscribe to and say that I am the Manager, Regulatory Programs, for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that I have full authority to execute this oath; that I have reviewed the foregoing; and that to the best of my knowledge, information and belief the statements made in it ar e true.

DATE 1987

.~ C.~ SOR SEN, Manager Regulator Programs On this day personally appeared before me G. C. SORENSEN to me known to be the individual who executed the foregoing instrument and acknowledged that he signed the same as his free act and deed for the uses and purposes herein mentioned.

GIVEN under my hand and seal this ~~

2 Jn+4 day of ~i C ,1987.

Notary u 1>c )n nd for the State of Washington

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Residing

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t ATTACHMENT 1 SNUBBER FUNCTIONAL TESTING FLOW CHART SAMPLE PLAN 2-GENERAL POPULATION REPRESENTATIVE SAMPLE TEST 37 SNUBBERS NO FAILURE TESTING COMPLETE YES TEST" 18 ADDITIONAL SNUBBERS FOR EACH FMG ESTABLISHED FROM GENERAL POPULATION CONTINUE FMG TESTING ESTA'BL ISHED PER FIG. 4.7-1 FAILURE YES DUE TO FAILURE YES TRANSIENT EVEN OR MANUF/DESIG DEFICIENCY EVALUATE EACH NO SNUBBER IN FMG PER 4.7.4.g NO TESTING TESTING COMPLETE COMPLETE TEST 18 SNUBBERS FOR EACH UNACCEPTABLE SNUBBER IN THE FMG OR ALL SNUBBERS IF NUMBER OF SNUBBERS IN THE FMG IS LESS THAN 18 TESTING NO YES AILURE COMPLETE