ML17313A903

Forwards Rev to Relief Request 12 Submitted 990420 to Second 10-yr ISI Interval.Revised Relief Request Discusses in More Detail Actions APS Will Take When There Is Identified Leakage from Bolted Connection

ML17313A903
Person / Time
Site:	Palo Verde
Issue date:	04/21/1999
From:	Ide W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
102-04274-WEI-A, 102-4274-WEI-A, NUDOCS 9904290295
Download: ML17313A903 (12)

Text

CATEGORY 1 REGULATO Y INFORMATION DISTRIBUTIO

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DOCKET 05000528 05000529 05000530 ACCESSION NBR:9904290295 DOC.DATE: 99/04/21 NOTARIZED: NO FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi QSTh+50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi AUTH.NAME AUTHOR AFFILIATION IDE,W.E.

Arizona Public Service Co.

(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT 'AFFILIATION Records Management Branch (Document Control Desk)

SUBJECT:

Forwards rev to relief request 12 submitted 990420 to second 10-yr ISI., interval. Revised relief request discusses in more detail actions APS will take when there is identified leakage from bolted connection.

DISTRIBUTION CODE: A047D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: OR Submittal: Inservice/Testing/Relief from ASME Code GL-89-04 E

NOTES: STANDARDIZED PLANT Standardized plant.

Standardized plant.

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NOTE TO ALL nRIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD)

ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED:

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10CFR50.55a(a)(3)

Palo Verde Nuclear Generating Station WilliamE. Ide Vice President Nuclear Engineering TEL 602/393-61 1 6 FAX 602/3936077 Mail Station 7605 P.o. Box 52034 Phoenix, AZ 85072-2034 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555-0001 102-04274-WEI/AKK/RKB April21, 1999

References:

APS Letter No. 102-04273-WEI/AKK/TNW/RKB,dated April 20, 1999, from W. E. Ide, APS, to NRC, "Second Inservice Inspection Interval (Relief Request Nos. 11 and 12)."

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2 and 3 Docket Nos. STN 50-528/529/530 Revision to Second Inservice Inspection Interval (Relief Request No. 12)

On April 20, 1999, Arizona Public Service Company (APS) submitted Relief Request Nos.

11 and 12 to the second 10-year Inservice Inspection (ISI) interval in the above referenced letter.

Enclosed is a revision to Relief Request No. 12, which supersedes the previous version submitted in the referenced letter.

The enclosed relief request does not contain substantive changes from the original, but has been rewritten to provide added detail and clarification. Specifically, the revised relief request discusses in more detail the actions APS will take when there is identified leakage from a bolted connection.

APS wishes to reconfirm that NRC approval for Relief Request Nos.

11 and 12 is requested by April 26, 1999.

APS considers the Alternate Testing methodology proposed in Relief Request No. 12 to be a commitment.

Should you have any questions, please contact Scott A. Bauer at (602) 393-5978.

9'704290295 9'P042i PDR ADQCK 05000528 Sincerely, 9

PDR WEI/AKK/RKB/rlh Enclosure.

ri A P cc:

E. W. Merschoff M. B. Fields J. H. Moorman

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ENCLOSURE I ASME SECTION XI RELIEF REQUEST NO. 12 TO THE SECOND 10 YEAR ISI INTERVAL FOR THE PALO VERDE NUCLEAR GENERATING STATION

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Relief Request No. 12 Examination of Bolted Connections Code Class Code Reference Examination Category item Numbers Component Description PVNGS Units 1,2,3 IWA-5250(a), 1989 Ed. and IWA-5250(a), 1992 Ed., 1992A B-P, C-H, D-B All Bolted Connections All Requirement IWA5250 (a) states: "The sources of leakage detected during the conduct of a system pressure test shall be located.and evaluated by the Owner for corrective action as follows......(2) Ifleakage occurs at a bolted connection, one of the bolts shall, be removed, VT-3 examined, and evaluated in accordance with IWA-3100. The bolt selected shall be the one closest to the source. of. leakage. When the removed bolt has evidence of degradation, all remaining bolting;in the connection shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100."

Alternate Testing PVNGS proposes the following alternative methodology to the requirements of IWA-5250(a),, either. the requirements of (a) or (b) below will be met for leakage at bolted-connections:

(a) The leakage shall be stopped, and the bolting and component material shall be evaluated forjoint integrity as described in (c) below.

(b) Ifthe leakage is not stopped, the joint shall be evaluated in accordance with IWB-3142.4 forjoint integrity. This evaluation shall include the considerations listed in (c) below.

(c) The evaluation for (a) and (b) above, is to.determine the suseptibility of the bolting to corrosion and failure. This evaluation will, at a

'minimum, consider the following factors:

(1) The number and service age of bolts, (2) Bolt and component material, (3) Corrosiveness of the process fluid, (4) Leakage location.and system function, (5) Leakage history at connection or other system components, and (6) Visual evidence of corrosion at connection (while the connection is assembled).

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~ Relief Request No. 12 (continued)

Alternate Testing (Continued)

Ifthe evaluation of the variables above indicates the need for further evaluation, then a bolt closest to the source. of leakage shall be removed.

The bolt willreceive a VT-1 examination and be evaluated and dispositioned in accordance with IWB-3517 of the ASME Code,Section XI. Ifthe removed bolting shows evidence of rejectable degradation, all remaining bolts shall be removed and receive a VT-1 examination in accordance with IWB-3140. Ifthe leakage is identified when the bolted connection is in service and the information in the engineering evaluation is supportive, the removal of the bolt for the VT-1 examination may be deferred until the next refueling outage.

Basis For Relief Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested on the basis that the proposed alternative would provide an acceptable level of quality and safety.

Specifically, PVNGS is asking for relief from the requirement to remove bolts without prior analysis to allow for instances where removal may not be warranted.

Removal of pressure retaining bolting at mechanical connections for visual, VT-3 examination and subsequent evaluation in locations where leakage has been identified is.not always the most prudent course of action to determine the condition of the bolting and root cause of the leak.

The Code requirement to remove, examine and evaluate bolting in this situation does not allow the Owner to consider other factors that may indicate the condition of the mechanical joint bolting. This requirement is unnecessarily prescriptive and restrictive.

Additional Information A situation frequently encountered at commercial nuclear plants such as PVNGS is the complete replacement of bolting materials (studs, bolts, nuts, washers, etc.) at mechanical joints during plant outages.

When associated system process piping is pressurized during plant start-up, leakage is sometimes identified at these joints. The root cause of this leakage is most often thermal expansion of the piping and bolting materials at the joint, which results in process fluid seepage at the joint gasket.

Proper retorquing of the joint bolting, in most cases, stops the leakage.

Removal of any of the joint bolting to evaluate for corrosion would be unwarranted in this situation due to the new condition of the bolting materials.

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Relief Request No. 12,(continued)

Approval 1

References In accordance with 10 CFR 50.55a(3)(a)(i) PVNGS is requesting permission to use the proposed alternative.

PVNGS will not.implement this alternative without prior authorization from the NRC.

ASME Section XI, Rules for Inspection and Testing of Components of Light Water Cooled Plants 1992 Edition and Addenda, Section IWA-5000.

ASME Section XI, Rules for Inspection and Testing of Components of Light Water Cooled Plants 1989 Edition, Section IWA-5000.

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