05000278/LER-1984-001, :on 840106,HPCI Turbine Exhaust Rupture Diaphragm Alarm Annunciated Following Startup.Caused by Inner Rupture Disk PSD3-23-6 Ruptured.Inner Rupture Disc Replaced

:on 840106,HPCI Turbine Exhaust Rupture Diaphragm Alarm Annunciated Following Startup.Caused by Inner Rupture Disk PSD3-23-6 Ruptured.Inner Rupture Disc Replaced

ML20087N855
Person / Time
Site:	Peach Bottom
Issue date:	03/30/1984
From:	Brooke Clark, Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-84-001, LER-84-1, NUDOCS 8404050090
Download: ML20087N855 (4)

LER-1984-001, on 840106,HPCI Turbine Exhaust Rupture Diaphragm Alarm Annunciated Following Startup.Caused by Inner Rupture Disk PSD3-23-6 Ruptured.Inner Rupture Disc Replaced

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
2781984001R00 - NRC Website

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Abstract While at power during surveillance testing, the HPCI turbine exhaust rupture diaphragm alarm annuciated following startup of the Unit'3 HPCI Turbine.

Investigation revealed that the inner rupture disc, PSD3-23-6, had ruptured.

Since the outer disc had not ruptured, the HPCI turbine remained operable until it was intentionally removed from service to replace the inner rupture disc.

Prior to removing the turbine from service, the systems required by Technical Specification 4.5.C.2 (RCIC, ADS, LPCI, and Core Spray) were verified to be operable.

Cause of the event is under investigation.

The rupture disc was replaced and HPCI was declared operable following surveillance test verification.

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, nne,.a. mu n n Description of the Event:

On January 6,1984, Peach Bottom Atomic Power Station was operating under normal conditions with both Units 2 and 3 at 100%

power.

At approximately 10:30 a.m., while conducting a surveillance test (ST-1.1 'HPCI Logic System Functional Test') on the Unit 3 HPCI system, the turbine exhaust rupture diaphragm alarm annuciated following startup of the HPCI turbine.

This alarm sences a pressure of greater than 10 psig between the inner and outer rupture discs located in series in a 16" line which taps off the turbine exhaust line and itself exhausts to the torus. room.

Investigation revealed that the inner rupture disc,

.PSD3-23-6 (manufactured by Continental Disc Corporation), had ruptured.

The setpoint_of the rupture disc is 175 psig.

The outer rupture disc, PSD3-23-7, had not ruptured, and therefore the HPCI turbine was not declared inoperable at that time.

At 4:44 p.m. on January 6,1984, the HPCI turbine was intentionally removed from service and declared inoperable in order to replace the inner rupture disc.

At 8:31 p.m. on January 6, 1984, the HPCI turbine, which was out of service for three hours and forty-seven minutes, was declared operable and returned to service following surveillance test (ST-6. 5 ) verification,.

As of January l',1984, the newly imposed 10CFR50.72 (b) (2) (iii) requires reporting an inoperable HPCI system within four hours on the Emergency Notification System (ENS).

Administrative Procedure A-31, Rev. 8 " Procedure for Notification of NRC",

addresses this new reporting requirement, however, the four hour report was not made.

The notification error was due to an administrative oversight as a result of an unfamiliarity with the new reporting requirements.

The NRC Site Inspector was notified of the reporting error.

Senior station personnel were informed on January 9,1984 of the importance of being familiar with the new reporting requirements.

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e,.msm.nn Consequences of the Event:

The outer rupture disc, PSD3-23-7, did not rupture therefore the HPCI system remained in service at the time of the occurrence.

Prior to blocking the HPCI system out of service, the Reactor Core Isolation Cooling System, Automatic Depressurization System, Low Pressure Coolant Injection System, and Core Spray systems were verified as operable as required by Technical Specification 4.5.C.2.

The HPCI system was returned to service within four hours after being declared inoperable.

Cause of the Event

Determination of the cause of the event is under investigation.

The scope of the investigation includes: 1) verifying the proper material of the rupture discf 2) a review of the piping configuration of the turbine exhaust line, 3) investigating the performance of the vacuum breakers between the torus air space and turbine exhaust line, 4) investigating'the turbine exhaust i

stop/ check-vdive performance, and 5) obtaining dynamic pressure test data of the turbine exhaust system.

A supplemental report will be submitted following completion of the investigation.

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Corrective Actions

ST 6.5 HPCI Pump, Valve, Flow, Cooler Test verified the Turbineexhaustpressureindic[atednormallyduringthe operability of the HPCI system after the inner rupture disc was replaced.

test and the system was returned to service.

A subsequent ST-6.5 l

was successfully completed on January 30, 1984 with all functions indicating normally.

L Previous Similar Occurrences LER's: 3-83-15/3L-0, 3-82-23/3L-0.

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PHILADELPHIA ELECTRIC COMPANY 23O1 MARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 (2153841-4000 March 30, 1984 Docket No. 50-278 Document Control Desk

.U.S. Nuclear Regulatory Commission Washington, DC 20555

SUBJECT:

Licensee Event Report

Dear Dr. Murley:

This LER deals with the failure of the Unit No. 3 HPCI turbine exhaust inner' rupture disc, PSD3-23-6, while performing surveillance testing on the HPCI system.

Reference:

Docket No. 50-278 Report Number:

3-84-01 Revision Number:

01 Event Date:

January 6, 1984

= Report Date:

March 30, 1984 Facility:

Peach Bottom Atomic Power Station RD #1, Delta, PA 17314 This LER is submitted pursuant to.the requirements of 10 CFR' 50.73 (a) (2) (v).

The revised portion of this LER is identified by a vertical bar in the margin.

Very truly yours, W. T. Ullrich Superintendent Nuclear Generation Division

!cc:

- Mr. A. R. Blough Site Inspector Dr. Thomas E. Murley, USNRC

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