ML19325F294

LER 89-016-00:on 891014,three of Four MSIVs Failed to Close within 5 & Declared Inoperable.Cause Not Determined. Hydraulic Sys for Each Valve Drained,Refilled W/Fresh Oil & Properly vented.W/891113 Ltr

ML19325F294
Person / Time
Site:	Salem
Issue date:	11/13/1989
From:	Miller L, Pollack M Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-016-02, LER-89-16-2, NUDOCS 8911200087
Download: ML19325F294 (6)

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O PSpf, Public Service Electric and Gas Company P.O.' Box 236 Hancocks Bridge, New Jersey 06038 Salem Generating Station November 13, 1989 U. S. Nuclear Regulatory Commission Document' Control Desk Nashington, DC 20555

Dear. Sir:

SALEN CENERATING STATION LICENSE NO. DPR-7S DOCKET NO. 50-311 UNIT NO. 2 LICENSEE EVENT REPORT 89-016-00 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73 (a) (2) (i) (B) . This report is required within thirty (30) days of discovery.

l l Sincerely yours,

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L. K. Miller i General Manager -  !

Salen Operations i

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On 10/14/89, during a controlled shutdown (for Maintenance), 3 of the 4 nain steam isolation valve (MSIVs) failed to close within 5 seconds,

• contrary to the requirements of Technical Specification Surveillance 4.7.1.5. Since the Action Statements for Technical Specification 3.7.1.5 only apply if no more than one (1) MSIV is inoperable and three (3) of .

the MSIVs were declared inoperable. Technical Specification Action I Statement 3.0.3 was entered. The root cause of this event has not been e determined to date. In the past, the hydraulic bypatse valves have been responsible for MSIV closure time concerns; therefore, the hydraulic bypass valves for each of the 3 MSIVs which did not close within 5 ceconds, were disassembled and inspected. No equipment problems / concerns cere identified. Investigation for the root cause of this event is continuing. A probabilistic risk assessment associated with the increased closure time has been initiated. A supplemental report will be issued to document the completion of investigations. The supplemental ,

I report will address the results of the probabilistic risk assessment, any l cdditional cort mive ectiont., required and the root cause of this event.

The MSIVs were declared operable upon successfully completing a re-test of the Technical Specification Surveillance at 1715 hours0.0198 days <br />0.476 hours <br />0.00284 weeks <br />6.525575e-4 months <br /> on November 4, 1989. The Unit u s returned to Mode 1 (Power Operation) on November 4, 1989 at 1910 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.26755e-4 months <br />. A License Change Request is being considered to codify Technical Specification 3.7.1.5 applicability if more than one of the MSIVs are kept closed (i.e., in their " safe" position).

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, .. LICENSEE EVENT REPORT (LER) TEXT CONTINUATION lilem Generating Station DOCKET NUMBER

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LEP NUMBER PAGE l Valt ' 2_ 5000 M 89_-Q1_6_QO 2 of__ 5 l EkAMT_AND__EYSTEM_IDENTIFIC4TJOjf1 j Westinghouse - Pressurized Water Reacton Energy Industry Identification Sys'.en (EIIS) codes are identified in the text as lxxl .

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• 1pKNTIElCATION OF OCCUERENCE:_ j Technical Specification Action Statement 3.0.3 Entry - Three of the 9 Four Main Steam Isolation Valves Declared Inoperable j Event Date: 10/14/89-Report Date: 11/13/89 l

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This report was initiated by Incident Report No.89-628.

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EQNDITIONS PRIOR TO OCCURRENCE 1 [l Mode 3 (Hot Standby); The Unit was in the process of shutting down in  !

support of required maintenance.

I DESCRIPTION OF OCCURRENCE:

On October 14, 1989 three (3) of the four (4) main steam isolation ,

valve (MSlVs) ISBl failed to close within the five (5) second period, i contrary to the requirements of Technical Specification Surveillance 4.7.1.5. Since the Action Statements for Technical Specification '

3.7.1.5 only apply if no more than one (1) MSIV is inoperable and i three (3) of the MSIVs were declared inoperable, Technical  ;

Specification Action Statement 3.0.3 was entered at 0545 hours0.00631 days <br />0.151 hours <br />9.011243e-4 weeks <br />2.073725e-4 months <br /> that day. .

Technical Specification Action Statement 3.0.3 states:  !

"When a Limiting Condition for Operation is not met except as  ;

provided in the associated ACTION requirements, within one hour action shall be initiated to place the unit in a MODE in which t the specification does not apply by placing it, as applicable, -

in: ,

1. At least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />,  !

, 2. At least HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and  !

3. At least COID SHUTDOWN within the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Where corrective measures are completed that permit operation (

under the ACTION requirements, the ACTION may be taken in accordance with the specified time limits as measured from the tins of failure to meet the Limiting condition of Operation. l Exceptions to these requirements are stated in the individual specifications."

Technical Specification Surveillance 4.7.1.5, is required to be performed every 92 days unless the Unit is on line. Normally this surveillance is performed during startup following a Unit shutdown.

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. LICENSEE EVENT REPORT (LER) TEXT CONTINUATION [

i 821em Generating Station DOCKET NUMBER LER NUMBER PAdE  !

Unit 2 5000311 89-016-00 3 of 5 I p18CRIPTION_OF OCCURRENCE: (contidl  ;

To prevent delays during the return to service of Unit 2 from she ~  !

recently completed maintenance outage, the MSIVs were operationally checked after entering Mode 3 during the controlled shutdown. The operational check was performed in accordance with procedure i SP(0)4.7.1.5, " Main Steam Isolation Valve Emergency Closure Time '

Response".

Technical Specification 3.7.1.5 is only applicable in Modes 1, 2 and 3; therefore, Technical Specification Action Statement 3.0.3 was ,

exited upon entering Mode 4 at 1015 hours0.0117 days <br />0.282 hours <br />0.00168 weeks <br />3.862075e-4 months <br /> the dame day. As stated in the Conditions Prior to Occurrence section, the Unit was in the process of being shutdown to Mode 5 (Cold shutdown), to support ,

maintenance outage activities. 6 APPARENT CAUSE OF OCCURRENCE 1 (

The root cause of this event has not been determined to date.

Investigations are continuing. The Corrective Action summary f identifies the results of the investigation (s) completed as of the i date of issue of this LER.

ANALYSIS OF_ OCCURRENCE:

The operability of the MSIVs ensures that no more than one Steam Generator (S/G) will blowdown in the event of a steam line rupture.  :

This restriction is required to minimize the positive reactivity l effects of the Reactor Coolant System cooldown associated with the l blowdown, and to limit the pressure rise within containment in the  ;

event the main steam line rupture occurs within containment.

The MSIVs are manufactured by Hopkinsons and are distributed by Atwood & Morrill. The valves are reverse acting double disk gate I valves, with two integral pistons and cylinders. They can be operated in either of two modes, electrohydraulic for normal open and closure and steam assist for emergency fast closure.

During normal operation the lower cylinder, which is divided into two chambers by a dividing plate that rides on the stem, has equal  ;

pressure between the two chambers by an equalizing orifice and drain tube. The valve is held open by the tight seating of the dump valves .

that provide a vent path for steam from the upper chamber. l Each MSIV has two air-operated dump valves. A three-way valve determines if either or both dump valves are used. The position of i each dump valve is controlled by a solenoid valve, located in the air supply line to each dump valve. The solenoid valves allow air

• pressure to hold the dump valve in the closed position unless an MSIV emergency closure signal is received.

In the emergency mode of operation, the lower cylinder is used to '

position the valve while the upper cylinder acts as a snubber. When

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 531em Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 89-016-00 4 of 5 j' MIALYSIS OF OQCURAENCE: (cor}11dl the dump valves open, steam evacuates from the upper chamber. The

[. equalizing orifice and drain tube cannot make up steam to the upper chamber as fast as it is exhausted and the resulting differential pressure closes the valve within five (5) seconds.

The MSIV five (5) second closure time is consistent with the origins 1 calculations associated with the accident analysis.

As identified previously, three (3) of the four (4) MSIVs would hkve

. possibly closed from approximately 6.5 secondo to approximately 7.5 r- seconds if required to do so in the event of a design base accident.

These times exceed the required 5 second closure time as identified in the Technical Specifications. Subsequently, this event is reportable in accordance with Code of Federal Regulations 10CFR 50.73 (a) (2) (1) (B) .

CORRECTIVE ACTION:

The hydraulic system for each valve was drained, refilled with fresh oil and properly vented.

In the past, the hydraulic bypass valves have been responsible for MSIV closure time concerns; therefore, the hydraulic bypass valves for each of the three (3) MSIVs, which did not close within five (5) seconds, were disassembled and inspected. No equipment problems / concerns were identified.

The hydraulic header for the 21MS167 valve was disassembled. Various valves and o-rings were replaced. These valves had minor oil leaks which did not affect the overall stroke time of the MSIV.

Each of the MSIV MS169 and MS171 dump valve closure times were checked in accordance with Surveillance Procedure 4.0.5-V-MS-5. The slowest valve was 2.26 seconds. The time limit, per the procedure, is ten'(10) seconds. The results of this test indicate that the dump valves probably operated properly during the MSIV fast closure testing during the shutdown.

l Other utilities who have experienced similar MSIV problems are being contacted. Also, the MSIV manufacturer and their distributor are being contacted.

Investigations as to the root cause of this event are continuing.

A probabilistic risk assessment associated with the increased closure time has been initiated.

l The MSIVs were declared operable upon successfully completing i re-test of the Technical Specification Surveillance at 1715 hours0.0198 days <br />0.476 hours <br />0.00284 weeks <br />6.525575e-4 months <br /> on November 4, 1989. During the surveillance testing, the dump valve stacks were observed with no significant observations noted. The

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l Unit was returned to Mode 1 (Power Operation) on November 4, 1989 at l

1910 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.26755e-4 months <br />.

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,d* LICENSEE EVENT REPORT (LER) TEXT CONTINUATION  ;

8:lem Generating 3tation DOCKET NUMBER LER NUMBER PAGE '

s Mpit_2 5000311 89-016-00 5_of 5 i

' CORRECTIVE ACTION:

(cont'd.L  !

< l A supplemental' report will bt issued to document the completion of i investigations. The supplemental report will address the results of  !

the probabilistic risk assessment, any additional corrective actions  !

required and the root cause of this event.

A License Change Request is being considered by PSE4G to modify j Technical Specification 3.7.1.5 applicability if more than one of the l MSIVs are kept closed (i.e., in their " safe" position).  ;

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s, General Manager - >

Salem Operations i MJP:pc SORC Mtg.89-110 l l

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