ML18344A414

LER 1979-037-00 for Palisades Nuclear Plant, Two Manual Three Inch Containment Isolation Valves in Bypass Line Were Discovered to Be Locked Open

ML18344A414
Person / Time
Site:	Palisades
Issue date:	12/10/2018
From:	Consumers Power Co
To:	Office of Nuclear Reactor Regulation
References
LER 1979-037-00
Download: ML18344A414 (2)

Text

Attachment to Licensee Event Report 79-037 Consumers Pover Company Palisades Uuclear Plant Docket 50-255 Event Descrintion On September 11, 1979, during performance of a local leak test *of Containment Building (CB) penetration 4a {CB exhaust valves bypass*), the tvo manual three-inch containment isolation valves in the bypass line were discovered to be locked open. At the time of discovery, the reactor was in a cold shutdown condition. A preliminary investigation was performed, and on September 14, it was determined that contrary to the requirements of Technical Specification 3.6.l, containment integrity had been breached during power operation. Accordingly,

• on September 14, 1979, this occurrence was deemed reportable per Technical Specification 6.9.2.a.(3) (abnormal degradation of the containment boundary).

Chronology of Events/Cause Descrintion On April 5, 1978, the HEPA filter in the CB exhaust valves bypass line was changed. In order to demonstrate the operability of the replacement filter, it vas functionally tested in accordance vith an approved test procedure.

Opening of the two three-inch manual isolation valves was required in order to obtain adequate flow through the filter. At the time the valves w-ere opened on April 6, 1978, the reactor was in a refueling shutdown condition, and containment integrity require!?lents vere satisfied. At the conclusion of the test; however, the valves were apparently not closed, and the subsequent plant start-up took place with containment integrity requirements not met.

The following elements a.re considered to be key factors related to this occ'...lrrence:

• The surveillance procedure governing the filter testing activities did not

• have adequate provisions for returning the system to normal .

• The tvo valves in question were not on the valve.line-up sheet vhich vas used to verify containment integrity prior to the plant start-up at the end of the refueling outage.

No evidence of an administrative review of the completed test procedure exists. An administrative review would have provided an opportunity to address system status, and might have led to discoverJ of the improper valve line-up prior to returning to power.

Corrective Actions

• Upon discovery, the affected valves were closed and locked in that position *

• The surveillance procedure which governs the filter testing will be revised such that return to se!"V'ice require!Jlents a!"e adequately addressed. In addition, all surveillance, cperating and other procedures vhich could impact on contai:::iment integrity will be reviewed and revised as necessary to assure that containment integrity requirements are satisfied.

• Also referred to in the FSAR as the post-accident hydrogen purge line.

(over)

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• The manual valves in the CB exhaust valves bn:>ass line will be added to the containment integrity valve line-up checklist. In addition, prints will be reviewed to verify tha~ all containment integrity isolation valves are included on the checklist, and a valkdown of all piping vhich penetrates the containment building will be made to verify print and checklist accuracy *

• This occur:-ence will be reviewed 'With atrolicable plant personnel. The requi:r:-ement to rigorously' follow procedures (ie, obtain administrative revievs when required) will be stressed.

• The fU!lction of the CB exhaust valves bypa.Ss 'Will be evaluated, and if possible, the line will be capped.

Probable Conseauences An evaluation of the consequences of this occurrence is still in progress *

. The follovd.n~ major elE:!!lents 'Will be investigated:

• The magnitude of the actual release to the main stack will be either calculated o:- estimated *

• The of:-site ef:ects during a postulated loss of coolant accident,will be estimated. To do this, consideration 'Will be given to the operation of the hydrogen purge regulating valve (CV-1804) and the downstream HEPA filter

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