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Part 21 Rept Re Failure of MSIV to Close Due to Malfunction of Valve.Initially Reported on 890914.Dual Solenoid Valves on All MSIVs Replaced or Refurbished Prior to Restart.Update to Be Submitted by Startup from Fourth Refueling Outage
	ML20247R925
Person / Time
Site:	Grand Gulf
Issue date:	09/18/1989
From:	; SYSTEM ENERGY RESOURCES, INC.
To:	Ebneter S; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
	REF-PT21-89-143-000 AECM-89-0175, AECM-89-175, PT21-89-143, PT21-89-143-000, NUDOCS 8910020107
	Download: ML20247R925 (6)
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EYSTEM E1MEntiY M8 MAN WC-w -. u.mv,au.. m . ,

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5 4 Nfjam September 18, 1989 U.S. Nuclear Regulatory Commission Region II-101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Attention: Mr. Stewart D. Ebneter, Regional Administrator

Dear Mr. Ebneter:

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 RD-89/001, Main Steam Isolation Valve Failure to Close Due to Solenoid Valve Malfunction AECM-89/0175 On September 14, 1989 System Energy Resources, Inc. (SERI) notified Mr.

Floyd Cantrell of your office of a Reportable Deficiency at Grand Gulf Nuclear Station (GGNS) Unit 1. The deficiency concerns a main steam isolation valve failure to close. This failure was caused by the disk material for the duel solenoid valve extruding through the exhaust port of the solenoid valve.

This deficiency was determined to be reportable under the provisions of 10CFR21 for GGNS Unit 1. Attached is the interim report for GGNS Unit 1. An update report will be submitted by startup from the fourth refueling outage.

Yours truly, j

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WTC:tkm Attachment cc: (See Next Page)

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lcc: Mr. D. C. liintz (w/a)

.Mr. T. H. Cloninger (w/a) l' Mr. R. B. McGehee (w/a)

Mr. N. S. Reynolds (w/a)

Mr..H. L. Thomas (w/o)

Mr. H.'O. Christensen (w/a)

Mr. L. L. Kintner, Project Manager (w/a)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 14B20-Washington, D.C. 20555 Director (w/3)

Office.of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission

. Mail Stop P1-137 Washington, D.C. 20555 Document Control Desk (w/a)

U.S. Nuclear Regulatory Commission Mail Stop P1-137 Washington, D.C. 20555 i

NLSAECM89091401 - 2

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4 Attachment to:

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AECM-89/0175 3 ,

t INTERIM ~10CFR21 REPORT

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11. 2Name and' address of the individual informing,the commission:

W.:T. Cottle ViceiPresident, Nuclear Operations P. O. Box 469=

Port-Gibson Mississippi 39150

2. = Identification.of.'the facility ... which ... contains a deficiency:

Grand Gulf Nuclear Station (GGNS) Unit . Port Gibson, Mississippi 39150

'3. Identification of the firm ... supplying the' basic component which

... contains a deficiency:

Automatic. Switch Company Florham Park, N.J. '07932

.4. . Nature.of the deficiency ... and.the safety hazard which ...-could be created by such a deficiency ...:

. A. Description of-the Deficiency On August 14, 1989 Main Steam Isolation Valve (MSIV) B21F0022B failed to close upon demand from automatic and remote manual' actuation ~ signals. Several minutes later the MSIV closed on its own. An investigation later revealed that the EPDM disk material for ASCO Model NP8323A20E dual solenoid valve B21SVF501B had extruded into the; exhaust port ofithe solenoid valve. When the solenoid valve was de-energized, the disk lifted off the exhaust port and the extruded material in the exhaust port was torn away from the disk' material. The extruded disk material blocked the exhaust port preventing the solenoid valve from exhausting air resulting in the MSIV rem:ining open. The extruded disk material was later blown out '

by normal air pressure allowing the solenoid valve to exhaust and the MSIV to close.

A contributing factor which caused the disk material to be extruded into the exhaust port appears to be related to the elastomer seal being energized dual. forced solenoid against pressure (not'the metal spring seat by)the pressure . This-extruded material appears to have been separated from the 1 remaining seat material due to the friction forces created by movement of the seat away from the exhaust port when the solenoid coils were de-energized on August 14, 1989.

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.The e'xtrusion process leading to. ultimate failure may be both temperature and. force dependent. It appears that seal o material softening allows:the process to begin. Seal softening.

depends on ambient' temperature, and extrusion depends on the softening and the-force applied by the solenoid onto the seal material. -If. seal' softening has.not occurred, then the amount of protrusion of the seal material'into the exhaust port is so E '

-small'that it has no affect.on valve operation.

The effect that ambient temperature has on the seal material softening is complex in nature. . While ambient temperature is known to be a controlling factor in chemical reaction rates and its effects can be predicted utilizing Arrhenius

., ' methodology, it appears that the softening or extrusion process can occur.at temperatures below those specified by the ASCO qualification reports.

.The ASCO qualification report specifies a life of eight. years at 140 degrees Fahrenheit ambient temperature for ASCO valves tested in an energized condition. A review of the available temperature data indicated that the' average ambient temperature t ~in~each of the inboard.and outboard MSIV areas at GGNS Unit 1

-has been below this temperature. However, evidence of substantial extrusion has'been found on all eight MSIV dual solenoid valve seats. . GGNS had no history of problems with these NP8323A20E MSIV solenoid valves until the time'of.

failure. These NP8323A20E dual solenoid valves were installed on all eight MSIVs in< March 1985 to replace the ASCO Model

-HTX8323A20V solenoid valves after.three MSIVs failed'to close due to the failure of thr'e HTX8323A20V solenoid valves. In

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e October 1985 and during the first refueling outage (Fall of 1986), a'NP8323A20E solenoid valve was removed, disassembled, and inspected. No degradation or other problems ~were found

.during either inspection. Successful' completion of fast closure of the MSIVs had been documented as recently as startup from the third refueling outage (April 29,1989).'Previousto this, successful fast closures were achieved on January 5 _1989 5 and August 16, 1988.

System Energy Resources, Inc. (SERI) contacted ASCO in August, 1989 for additional information relating to potential thermal aging effects on the EPDM seal material utilized in the NP8323A20E valves. ASCO provided new, more conservative, internal heat rise values than those previously received by SERI. SERI subsequently performed an evaluation of the thermal endurance service life of these solenoid valves using the more conservative ASCO heat riso values and thermal endurance test i data from tests performed for Cleveland Electric's Perry Plant. ;

Conservatively assuming a constant 135 degree Fahrenheit NLSMISC89091404 - 2

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' ,[ , [ , AECM-89/0175l l ambient temperature (equal to maximum anticipated drywell-temperature), this evaluation resulted in an expected thennal- l endurance l level of at'least 5.17 years. -All eight of the MSIV l

, ' solenoid valves-had been in services.less than-this period, j i B' . Analysis of' Safety Implications j

'The ASCO NP8323A20E dual. sol'enoid valves are utilized'as three-way, normally energized, dual solenoid operated main pilot control valves to. reposition the main control valves in the pneumatic control units. The pneumatic control unit for 1 each MSIV:is attached to the valve's air operated cylinder and are utilized to control positioning of.the MSIVs.

The MSIVs utilize air-to open and spring to close with air ,

assist actuators. The air supply to the pneumatic' operated-cylinder is control. led by a four-way pilot operated valve which applies air. pressure to either the' top or_ bottom end of- i the air cylinder operator. This four-way pilot operated-valve is in turn controlled by.a three-way normally energized dual solenoid-operated valve. To open the MSIV, either or both

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solenoids on the three-way dual solenoid valve are energized to feed air-pressure to.-the piston ~of the four-way pilot operated valve. which in turn shifts position to feed air pressure to the bottom, side of the air operating cylinder and

.(at_ the same time) exhaust air from the top side of the air operated ~ cylinder. To close the MSIV;both solenoids on the three-way dual solenoid valve must be de-energized to allow the

.four-way valve to shift position to feed air. pressure to the top side of the air operating cylinder and (at the same time) exhaust air from the bottom side 'of.the air operated cylinder..

At GGNS there are four main steam lines and each steam line.is equipped with two MSIVs. One'in each line is placed as close

.as possible to the inside of the drywell and the other valve is just outside the containment. The MSIVs are designed to close fast enough to limit release of radioactivity to the

, . environment to less than the. limits of 10CFR100 in the event of a guillotine break of one steam line outside the primary containment.

Based on the deficiency described above, a potential existed for both ASCO NP8323A20E dual solenoid valves to fail and not allow the two MSIVs to fast close on a main steam line in the event of a guillotine break on that line.

Therefore based on the redundant basic component guidelines, as defineo in NUREG-0302, it is conservatively postulated that a failure of both MSIVs in a steam line potentially existed.

This failure, coincident with a postulated main steam line break outside the primary containment could have resulted in a reduction in the degree of protection provided to public health and safety.

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5. The date on which the information of such deficiency ... was-obtained:

System Energy Resources, Inc. received information of the deficiency on August 28, 1989. An evaluation under the guidelines of 10CFR21 was completed on September 13, 1989.

-6. In the case of the basic component ... the number and location of all such component: 1 There are nine NP8323A20E dual solenoid valves at GGNS Unit 1, one located on each of the eight Main Steam Isolation Valves and one spare located in the warehouse.

We do not have knowledge of the location of other defective equipment.

7. The corrective action which has been taken ... the name of the individual responsible for the action; and the length of time that has been ... taken to complete the action:

A. Corrective Actions Taken The NP8323A20E dual solenoid valves on all eight MSIVs were replaced or refurbished prior to plant restart.

B. Responsible Individual W. T. Cottle Vice President, Nuclear Operations System Energy Resources, Inc.

C. Length of Time.to Complete Actions SERI will continue with an accelerated replacement or refurbishment schedule for the NP8323A20E dual solenoid valves and in parallel is pursuing design change options such as the use of two single solenoid valves in place of the single dual solenoid valve design.

The length of time to complete this action is indeterminate at this time. However, SERI will provide a status update by startup from the fourth refueling outage.

8. Any advice related to the deficiency ... that has been, is being, or will be given to purchasers or licensees:

As the deficiency did not originate with SERI, we have no further advice to offer.

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