05000346/LER-1980-014-03, /03L-0:on 800208,pressurizer Sample Sys Containment Isolation Valve RC240B Failed to Close Twice. Caused by Improper Torque Switch Setting & Stripped Screw on Closing Contactor.Settings Readjusted & Switch Replaced

/03L-0:on 800208,pressurizer Sample Sys Containment Isolation Valve RC240B Failed to Close Twice. Caused by Improper Torque Switch Setting & Stripped Screw on Closing Contactor.Settings Readjusted & Switch Replaced

ML19344D277
Person / Time
Site:	Davis Besse
Issue date:	03/06/1980
From:	Rudolph J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19344D274	List: 05000346/LER-1980-014, Forwards LER 80-014/03L-0 05000346/LER-1980-014-03, /03L-0:on 800208,pressurizer Sample Sys Containment Isolation Valve RC240B Failed to Close Twice. Caused by Improper Torque Switch Setting & Stripped Screw on Closing Contactor.Settings Readjusted & Switch Replaced
References
LER-80-014-03L, LER-80-14-3L, NUDOCS 8003110628
Download: ML19344D277 (3)

LER-1980-014, /03L-0:on 800208,pressurizer Sample Sys Containment Isolation Valve RC240B Failed to Close Twice. Caused by Improper Torque Switch Setting & Stripped Screw on Closing Contactor.Settings Readjusted & Switch Replaced

Event date:
Report date:
3461980014R03 - NRC Website

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NHC F OHr.1 SCG U.S. NUCLE AR HEGULATORY COMMlZION 87 77)

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O bJ 61 DOC A L T F.trM A od LJ EVENT DATE 14 13 HEPORT DATE JJ EVENT DESCRIPTION AND PACB ABLE CCNSEQUENCES h o a [ On 2/8/80 at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> the pressurizer sample system containment isolation valve l

[ [o la j l RC240B would not close. The station er tred action statement (d) of Technical Speci-l l fication (TS) 3.6.3.1 which required the station to be in hot standby (Mode 3) within l o 4 lo[s;l the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

The station was in Mode 3.

On 2/15/80 at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> RC240B ag.iin l l failed to close. This time the station was in Mode 1.

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_ l o l 7 ] I statement (b) of T.S. 3.6.3.1 w!ich required the penetration be isolated in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

l [oggl [ There was no danger. The redundant isolation valve RC240A was operable. (NP-33-80-18);

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44 47 CAUSE DESCRIPTION AND COF:RECTIVE ACTIONS h i o l The cause of the first incident was an improper torque switch setting.

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i i 1 ance Work Order 80-1537 on 2/8/80 the settings were readjusted. The valve was declareq!

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TLLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-18 9

DATE OF EVENT: February 8, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Pressurizer Sample System Containment Isolation Valve RC240B would not close Conditions Prior to Occurrence: The unit was in Mode 3 with Power (MWT) = 0, and Load (Gross MWE) = 0.

Description of Occurrence: While trying to terminate pressurizer sample flow at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on February 8, 1980, operations personnel found that RC240B would not go closed.

This failure put the station in the action statement "d" of Technical Specification 3.6.3.1.

This technical specification requires this containment isolation valve to be operable with an isolation time of 30 seconds in Modes 1 through 4.

This action statement required the station to be in at 1 cast hot standby within the next six hours and in cold shutdown within the following thirty hours.

At 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on February 15, 1980, RC240B again failed to close. At this time, the unit was in Mode 1 with a gross output of 916 MWe. The station entered the action statement "b" of Technical Specification 3.6.3.1 which required the af fected penetra-tion be isolated within four hours by use of at least one deactivated automatic valve secured in the isolation position.

Designation of Apparent Cause of Occurrence: The first occurrence can be attributed to insuf ficient information on Maintenance Work Orders (MW0s) that concern the trouble-shooting and/or repair of Limitorque operators. They did not specify the correct torque switch setting, and it does not require reporting the as found and as lef t settings. The valve was torquing out due to the torque switch settings in the Limitorque operator. The limits were set at 1.25 for closing and 3.0 for opening.

The recommended setpoint for this valve is 2.0 for both opening and closing. When the failure history of RC240B was researched, no documentation could be found that called for the improper setting of the torque switch.

When the valve failed a second time, investigation found that the torque switch was also faulty. A stripped screw on the closing contactor circuit was causing the closing circuit to break before the valve actually torqued out.

Analysis of Occurrence: There was no danger to the health and safety of' the public or to station personnel. The redundant isolation valve (RC240A) was operable had con-tainment isolation been required.

,LER #80-014 m _

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION 'FOR LER NP-33-80-18

Corrective Action

Under Maintenance Work Order 80-1537 on February 8, 1980, the open and close torque switch settings were set to the recommended value of 2.0, and the valve was stroked several times. The valve was successfully retested per ST 5064.01, " Containment Isolation Valves Post Maintenance Test" and declared opera-ble at 1920 hours0.0222 days <br />0.533 hours <br />0.00317 weeks <br />7.3056e-4 months <br /> on February 8, 1980. This removed the station from the action statement of Technical Specification 3.6.3.1.

On the second valve failure, the torque switch was replaced on February 15, 1980 under Maintenance Work Order 80-1579. The open and close torque switch settings were set at 2.0 and the valve was cycled several times. The valve was again retested per ST 5064.01 s,d declared operable at 0840 hours0.00972 days <br />0.233 hours <br />0.00139 weeks <br />3.1962e-4 months <br /> on February 16, 1980 which removed the station from the action statement of Technical Specification 3.6.3.1.

As a corrective measure for improper torque switch settings, the open and close set-points will be stated on any maintenance work order issued that concerns the trouble-shooting and/or repair of Limitorque operators. Presently, deviation from the recom-mended torque switch settings is not allowed without prior Power Engineering approval.

There have been previous failures due to settings which had to be in-creased within limits to make the valve operable, see Licensee Event Reports NP-33-79-104, Failure Data:

NP-33-79-85, Ni-33-79-45 and NP-33-78-33.

There have been previous failures due to failed torque switches which were replaced, see Licensee Event Reports NP-33-79-33 and NP-33-77-83.

LER #80-014 e

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