ML20092H516

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Discusses Upward Setpoint Drift on Target Rock Model 7567F two-stage Main Steam/Safety Relief Valves,Per SER (NUREG-0991).Caused by Bonding Between Pilot Disc & Seat & Lack of Clearance Between Pilot & Labyrinth Seal
ML20092H516
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 06/22/1984
From: Kemper J
PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To: Schwencer A
Office of Nuclear Reactor Regulation
References
RTR-NUREG-0991, RTR-NUREG-991 NUDOCS 8406260146
Download: ML20092H516 (3)


Text

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.* O PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STRECT P.O. BOX 8699 PHILADELPHIA. PA.19101 msin4i.4eo2 JUN 2 21984 JOHN S MEMPER WKE PNESIDENT Mr. A. Schwencer, Chief Docket Nos 50-352 Licensing Branch No. 2 50-353 Division of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Limerick Cenerating Station, Units 1 & 2 Opening Pressure of Two-Stage Target Rock Safety / Relief Valves

References:

(1) NUREC-0991 Supplement No.1 (Limerick Safety Evaluation Report)

(2) Telecon - May 3, 1984 between F. Cherny (NRC) and J. N. Mollick and J. L.

Phillabaum (PEco)

Dear Mr. Schwencer Reference (1) identified opening pressure of the two-stage Target Rock safety / relief valves as outstanding issue twenty-eight. The following information is provided for your review as agreed upon in the reference (2) conference en11.

As a result of the identification of upward setpoint drif t on a number of Target Rock two-stage Main Steam Safety / Relief Valves (Model No. 7567F), the BWR Owners' Group approved establishment of a Committee to investigate the problem with funding made available by participating utilitten. Cencral Electric administered the proposed program and furnished substantial technical input. Other technical support organizations were Target Rock Company, Sol Levy Inc., and Wylie Laboratorien.

On November 10, 1983, the Committee met with the NRC and presented the results of their investigation and recommended actions to correct the problem. A final report on the subject will he trannmitted to the NRC before July 1, 1984.

In summary, the report identifies two problemn that cause the upward setpoint drift and offers the following corrective actions to prevent or mitigate the problem:

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1. a) Problem - a corrosive action that creates bonding between the pilot disc and seat.

b) Corrective action - periodically refurbish the pilot disc and seat.

2. a) Problem - insuf ficient clearance between the pilot stem and the labyrinth seal, thus restricting free stem motion.

b) Corrective action - check to assure that manufacturer recommended clearances exist. Make any necessary clearance corrections.

In addition, General EDetric will gather and review all SRV maintenance and test reports for two (2) years to assure that the recommended corrective actions are satisfactorily resolving the high setpoint drif t problem.

Cencral Electric has also issued supplement 14 to their SIL 196 to all BWR Owners concerning the problem. Its recommendations are in agreement with the committee findings and recommendations.

Although Unit I at '.imerick Generating Station is not yet operatint:,

its two-stage Target Rock Main Steam Relief Valves were returned to Target Rock for implementation of all applicable supplements of SIL 196 including supplement 14. They are new back on site with all necessary changes, inspections and confirmations of pressure lif t settings.

Consistent with the reference (2) conference call, we believe that this information will permit you to satisfactorily close outstanding issue twenty eight.

Sincerely, W -*

See Attached Service Lint JNM/pd 16/9 l

I l

e . s l

t cc Judge litwrenco Dronnor

Judge Richani F. Colo l Troy B. Connor, Jr. , Esq.

l Ann P. IIodgdon, Ecq.

l Mr. Frank R. Pzxrnno Mr. Rolwrt L. Anthony Charles W. Elliot, Esq.

Zori G. Forkin, Esq.

Pir. Ttrmin Corunhy Director, lYnna. Iturgency l thnagrrent Agency l Anqua R. Iovo, Esq.

Diwid Wersan, Ecq.

Palmrt J. Sugamin, Eng.

Spenco W. Perry, Enq.

l Jay it. Gutierroz, Esq.

l Attnic Safety & Licensing Appeal lutnl Atomic Safety & Licensing Doant Panel l

Docket & Servico Section

! thrtha W. Dunh, Eng.

l Mr. Jamo Wiggina Mr. Tinothy R. S. CmT i nll

!!n. Phyllin Zit:or Judge Potor A. Morrin l

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