ML20062G453

Forwards SE Supporting Util Actions to Address Indication in Reactor Vessel Recirculation Riser nozzle-to-safe End Weld

ML20062G453
Person / Time
Site:	Limerick
Issue date:	11/20/1990
From:	Clark R Office of Nuclear Reactor Regulation
To:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
Shared Package
ML20062G457	List: ML20062G453 ML20062G458
References
TAC-77848, NUDOCS 9011290241
Download: ML20062G453 (3)

Text

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,e s UNITED STATES NUCLE AR REGULATORY COMMISSION 5 I g  ;/ WASHINGTON, D. C. 2055$

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November 20, 1990 l

! Docket No. 50-352 -

Mr. George A. Hunger, Jr.

Director-Licensing, MC 5-2A-5 )

Philadelphia Electric Company I l ' Nuclear Group Headquarters '

l Correspondence Control Desk P. 0.-~ Box No. 195 Wayne, Pennsylvania 19087-0195 I

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SUBJECT:

INDICATION IN REACTOR YESSEL-RECIRCULATION RISER N0ZZLE TO SAFE END-WELD, LIMERICK GENERATING STATION, UNIT 1, (TAC NO. 77848)

Your letter of.0ctober 23, 1990 presented the results of the're-examination of'-

the indication in the reactor vessel N2H recirculation riser nozzle-to-safe end weld during the current (third) refueling outage for. Limerick, Unit 1.

The indication was initially detected as a result of ultrasonic testing (UT) t examinations performed during the Unit I second refueling outage (January 13-toMay-15,1989).- A comparison of the September 1990 examination results with those foued in 1989 showed a small change to the existing indication and an extension of the circumferential length of the existing indication by l'.6-inches (from 7 t.c 8.6 inches), with a maximum depth of 0.47 inches.-

You, along with your consultant, the . General Electric (GE) Company, evaluated the recent N2H weld UT inspection results and concluded that operation of Unit ,

1 for.the next (fourth) fuel cycle is acceptable without taking corrective  ;

actions at this time. You connitted to continued monitoring-using the on-line >

crack growth monitoring system and specific actions related to specimen crack '

growth values as described in your letter of October 5,1990. We request that you notify us_ if the. Crack Advance Verification System -(CAVS) becomes inoperable. . Even more important was the connitment in; the _ action-plan you

, presented to us on October 5,1990 to maintain reactor water chemistry at l optimum values during the fourth cycle. As discussed in the' enclosed safety-evaluation, we have concluded that:the N2H' nozzle-to-safe end weld is acceptable for continued service during cyc_le 4. We concur with your analysis -

which estimates that growth of the existing flaw will be minimal with-improved water chemistry and should not exceed the ASME Code Section XI allowable limit established by fracture mechanics analysis during one more-operating cycle. ,

We appreciate your installation of the: experimental acoustic emission (AE)L monitoring equipment developed under one of our research programs as well-as i

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the funding you- provided during the past cycle to evaluate the resul:i,. f, '

hope it will provide supplemental information on the flaw growth rate in the N2H nozzle. Until the performance of the AE system is evaluated, it is not expected that the results can be used to-quantify the extent of crack growth.

Sincerely, Original signed by Richard J. Clark 1

Richard J. Clark, Project Manager Project Directorate'l-2 Division of Reactor Pr Jects - I/II Office of Nuclear Reactor Regulation

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,Mr.. George A. Hunger, Jr. November 20, 1990 the funding you provided during the past cycle to evaluate the results. We hope it will provide supplemental information on the flaw growth rate in the N2H nozzle. Until the performance of the AE system is evaluated, it is not expected that the results can be used to quantify the extent of crack growth.

Sincerely, J

eti . Cl rk, Project Manager Project Directorate 1-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation

Enclosure:

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Troy B. Conner, Jr. , t.'.qu i re - Mr. Thomas Gerusky, Director Conner and Wetterhahn Bureau of. Radiation Protection 1747 Pennsylvania Ave.. N.W. PA~ Dept. of Environmental-Resources!

Washington, D. C. 20006 - P. O. Box 2063' Harrisburg, Pennsylvania .17120-Mr. Rod Krich 52A-5

Philadelphia Electric Company . Single Point'of_ Contact

i. 955 Chesterbrook Boulevard P. 0. Box 11880 Wayne, Pennsylvania 19087-5691 Harrisburg,. Pennsylvania- 17108-1880- I Mr. Graham M.'Leitch, Vice President Mr. Garrett Edwards Limerick Generating Station. Superintendent-Technical Post Office Box A Limerick Generating = Station' Sanatoga, Pennsylvania 19464 P. O. Box A' Sanatoga, Pennsylvania 19454 Mr. Marty J. McCormick, Jr.

Plant Manager Mr. Gil'J. Madsen.

Limerick Generating Station Reuglatory Engineer P.O. Box A Limerick Generating Station t Sanatoga, Pennsylvania 19464 P. O. Box A Regional Administrator l

U.S. Nuclear Regulatory Commission _ Library Region I US Nuclear. Regulatory Comission u 475 Allendale Road Region 1-l King of. Prussia, PA 19406 475 Allendale Road.

King of Prussia,-PA 19406 .

Senior Resident:In mector US Nuclear Regulato y Commission P. O. Box 596 Pottstown, Pennsylvania- 19464-Mr. John Doering Project Manager.

Limerick Generating Station -

P. O. Box A Sanatoga, Pennsylvania .19464-Mr. Larry Hopkins Superintendent-Operations Limerick Generating Station P. O. Box A Sanatoga,. Pennsylvania 19464

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