05000260/LER-1983-074, Updated LER 83-074/03X-1:on 831105 & 10,turbine Exhaust Inner Rupture Diaphragms Failed During HPCI Initiation. Investigation Underway to Determine Cause of Failures. Diaphragms Replaced & HPCI Returned to Svc

Updated LER 83-074/03X-1:on 831105 & 10,turbine Exhaust Inner Rupture Diaphragms Failed During HPCI Initiation. Investigation Underway to Determine Cause of Failures. Diaphragms Replaced & HPCI Returned to Svc

ML20082R635
Person / Time
Site:	Browns Ferry
Issue date:	12/05/1983
From:	Green H, Roberts W, Widick R TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
LER-83-074-03X, LER-83-74-3X, NUDOCS 8312130244
Download: ML20082R635 (3)

LER-2083-074, Updated LER 83-074/03X-1:on 831105 & 10,turbine Exhaust Inner Rupture Diaphragms Failed During HPCI Initiation. Investigation Underway to Determine Cause of Failures. Diaphragms Replaced & HPCI Returned to Svc

Event date:
Report date:
2602083074R00 - NRC Website

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qyl l During start'up of HPCI during pe'rformance of Special Test 8211 on 11/5/83, ,

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. HPCI initiation resulting f rou a unit scram, the inner diaphragm ruptured.

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.t Tennessee Valley Authority , Form BF 17 Browns Ferry Nuclear Plant BF 15.2 2/19/82 LER SUPPLEMENTAL INFORMATION k "

' BFRO 260 / 83074 al Technical Specification Involved 3.5.E Reported Under Technical Specification 6. 7_.2.n. (s)

• Date Due NRC 12/6/83

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Event Narrative:_

Units 1 and 3 were in refueling outages; unit 2 was operating normally at 98 percent power. Unit 2 was the only unit affected by this event. On g November 10,1983, unit 2 scrammed and the high-pressure cooling injection

system (HPCI) received an auto initiation signal to inject water into the 4

ve s se l . The HPCI responded to the signal but isolated immediately due to a blown inner turbine exhaust rupture diaphragm which caused an inope rable

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condition (T.S. 3.5.E). The rupture diaphragm is a Fike, Model 16-CPV-CBT.

l The rupture diaphragm was replaced and surveillance instructions (SI) 4.5.E.1.d and e (HPCI Turbine and Pump Flow Test) and SI 4.5.E.1.c (HPCI HOV Operability) were successfully performed and the HPCI system returned to service. The HPCI system was inoperable for approximately 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />.

Redundant systems were rvailable and subsequently tested, as required by T.S. 3.5.3. T.S. 3.5.E allows seven days' operation with HPCI inoperable.

There was no effect on public health and safety.

A failure of the inner turbine exhaust rupture diaphragm had occurred

( previensly on November 5,1983 during the performance of Special Test 8211, t HPCI Temporary Startup Modifications. The HPCI had been declared inoperable for the performance of this test, and redundant systems had been j proved operable af ter operability sis were satisf actorily completed. The exact cause of the rupture diaphragm to fail is not known. The suspected cause is water entrainment in the exhaust steam because the gland seal condenser.. level switch was subsequently found to be operating improperly.

This owTtch inoperability may have allowed water to accumulate in the turbine casing. The diaphragm was replaced And HPCI declared operable.

The HPCI was inoperable for 38 hours4.398148e-4 days <br />0.0106 hours <br />6.283069e-5 weeks <br />1.4459e-5 months <br />, 35 minutes for both the special test and diaphragm repairs.

l A followup report will be submitted upon completion of the investigation l

being conducted to determine f ailure cause. Expected completion date for testing and investigation is Ja'anary 15, 1984.

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BFRO-50-259/79027, 80029; 260/ 80017, 80032;-296/ 81015,- 81016 I

Retention: eriod - Lifetime; Responsibility - Document Control Supervisor

• Revision: Vj[

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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401 1750 Chestnut Street Tower Il qq DEC !

P2; 26 December 5, 1983 Mr. James P. O'Reilly, Director U.S. Nuclear Regulatory Commission Suite 2900 101 Marietta Street, NW.

Atlanta, Georgia 30303

Dear Mr. O'Reilly:

TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PLANT UNIT 2 - DOCKET NO. 50-260 - FACILITY OPERATING LICENSE DPR REPORTABLE OCCURRENCE REPORT BFRO-50-260/83074 - REYlSION 1 The enclosed report is a supplement to my letter dated November 22, 1983, concerning system isolation caused by a blown turbine exhaust rupture disc. This report is submitted in accordance with Browns Ferry unit 2 Technical Specification 6.7.2.a(5).

Very truly yours, TENNESSEE VALLEY AU ORITY 4A H. J. Green Director o'f Nuclear Power Enclosure cc (Enclosure):

Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Records Center institute of Nuclear Power Operations Suite 1500 1100 Circle 75 Parkway Atlante, Georgia 30339 nI:rICI AL COI NRC Inspector, Browns Ferry

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