ML18058A432

LER 92-031-00:on 920402,left Channel DBA Sequencer Inadvertently Activated.Caused by Lack of Adequately Detailed Procedures.Procedures RT-13A & B & RT-8C & D revised.W/920504 Ltr

ML18058A432
Person / Time
Site:	Palisades
Issue date:	05/04/1992
From:	Slade G, Smedley R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-031, LER-92-31, NUDOCS 9205120272
Download: ML18058A432 (5)

Text

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. General Manager POWERiNii MICHlliAN"S PROliRESS . . .

Palisades Nuclear Plant: 27780 Blue Star Memorial. Highway, Covert, Ml 49043 May 4, 1992 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DbCKET 50-255 - LICENSE DPR-20 PALISADES PLANT . _ .

LiCENSEE EVENT REPORT 92-031 - INADVERTENT ENGINEERED SAFETY FEATURE ACTUATION CAUSED ~y INADEQUATE TEST PROCEDURES _ *

• Licensee Event Report (LER)92-031 is attached .. This ~vent i~ r~portable in

• accordance with IOCFR50.73(a)(2)(iv) as an event that result~d in the

• a~tuation of an Engineered Safety Feature;

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• 1.1.. - - y , , _ . , , . . _ . ry~rtM tinlli 1111 ' I ABSTRACT On Aprfl 2, 1992, with the primary system solid and pressurized to 250 psig in the cold shutdown condition, the left channel Design Basis Accident (OBA) sequencer was inadvertently activated by technici~ns preparing to test the 1eft channel Normal Shutdown Sequencer (NSD). The OBA sequencer operated properly and actuated the equipment it.w~s programmed to actuate including Low "

Pressure Safety Injection (LPSI) pump P-67B and Containment Air Cooler fan V-4A. The inadvertent activation of the OBA sequencer was caused by improperly connecting test equipment which had been incorrectly modified.

After verifying that left channel OBA equipment had been properly actuated, the*operators returned the left channel OBA equipment to its pre-event status.

Corrective action in the form of: 1) Revising test prricedures, 2) Revising the labeling on test cable plugs and installing labels on the sequencer test jacks, and 3) Revising drawings to identify all the wires in the seque.ncer test cables is planned as a result of this event.

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' - Taft*"9!9-*,_.. --.-.e,..,. .. *111111 EVENT DESCRIPTION At 0829 hours0.00959 days <br />0.23 hours <br />0.00137 weeks <br />3.154345e-4 months <br /> on April 2, 1992, with the primary coolant system [AB] solid at 250 psig in the cold shutdown condition, Instrument Technicians were connecting .equipment to test normal shutdown operation of the left channel

• sequencer when the Design Basis Accident {OBA) operation of the se4uencer was activated and actuated Low Pressure Safety Injection (LPSI) pump P-67B [BP;P]

and Containment Air* Cooler fan V-4A [BK;FAN]. *Plant operators, after verifying that the left channel OBA equipment had actuated properly, returned that equipment to pre-event status. This event did not involve the failure of any equipment important to safety.

CAUSE OF THE EVENT The ~ause bf this event was the improper installation of improperly mtidified test equipment cables [CBLl]. The root cause was the lack of adequately detailed procedures, the_lack of adequately labeled test cables and test connectors [CON], and the lack of detailed drawings which properly identify

• all the wires in the test ~ables and their associated termination points oh the test cable conriectors.

ANALYSIS OF THE EVENT Bo~h the NSD and OBA sequencer operations are tested during refueling outages -

to verify the programmed starting times of the appropriate equipment. Four

• surveillance procedure.s perforin this verification~ They ar~:

A.* For the Normal Shutdown Sequ~ncerTest, RT -13A is u.sed for the Left Channel ; and RT-13B fs used for the Right Channel~

B. For the Engineered Safeguards System Test (which test the OBA sequencer),

RT-SC is-used for Left Channel; and RT-80 is used for ~he Right-Channel; The test equipment used to perform the time interval measuremerit is called a

. "Data Acquisition System" (DAS). During each of the above listed surveillances, the DAS measures the actual time interval for individual contact closures as the sequericer is allowed to operate.

• For the measurement process, the DAS is ~lec~ritally connected ~nto the w~ring schemes of all of the input and output contacts on the sequencers. This interconnettion is done with two test cables~ Each test cable had a plug

[CON] which was labeled Number 1 for one cable and Number 2 for the other cable at the end which connects to the sequencer cable jacks and a* barrier terminal strip at the end which connects to th~ DAS. The sequencer has a pair of unlabeled jacks which mate with the plugs on the test cables.

Durin~ the preparatipn for the tests, the DAS equipment that was previously used could not be made operational. Therefore, a new and different type of DAS was prepared for use. The old DAS had always been connected to the

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.i sequencers and operated by the Consumers Power Company General Office based System* Maintenance and Construction Services Department {SMCSD). The new DAS requi.red conneetion to the sequencers and operation by the plant Instrument and Control Department {I&C). Thus, the need to ch~nge the type of DAS equipment resulted in a different work group having to connect the test cables to the sequencers which was a contributing factor to the cause of the plugs on the test ~ables being incorrectly connected to* their.matching jacks on the left channel sequencer {plug~ Numbet 1 and the Number 2 were reversed). This error; in combination with a different group performing the test, most probably occurred for one or all of the following reasons:

1. Tw6 pl~nt ~iints, t~l508 and E~l509, desc~ibe the connection of the DAS to th~. two sequencers. Connection to the left channel sequencer uses E-1508, while connection to the right channel sequencer uses E-1509. These prints were referenced in procedures RT-BC and RT-80, however they were not adequately referenced in procedures RT~l3A and RT -138.

• .2. Proper.connection of the cable plugs and sequencer jacks is not a straightforward taik. To a~sure the cable plug~ are mated with the

. proper sequencer jacks; the wires in the cable must be physically traced from the tetminal strip, compared with the drawing, and a determination made as to which plugs and jacks ar~ the proper ~atch.

Existing procedures-did not.iriclude th1s information. *

3. For proper installation, cable test plug Number 1 was required to be connected to the sequencer test jack which was attached to a cable leading to terminal strip TBL-2; and, cable test plug Number 2 was required to be connected to the sequencer test jack attached to a cable leading to terminal strip TBL-1.

Addittonally, a second error was made when the cables we~e prepared for the test. When the old DAS was used, it was physically located in the cable spreading room .. For this outage, arrangements were made to locate the new DAS in the Control Room. To avoid the congestion which would be cause9 by the long cables which had been required when the DAS was located in the Cable Spreading Room, the test cables were shortened. During the cable short~ning process, several conductors in the cable were observed as "extras." These "extra" wires caused some confusion because plant drawings did not identify a11 of the conductor.s in the cab 1es nor did they identify the corresponding pin connectibns on t~e cable plugs. Work instructions which were used t6 -

control the cable shortening stated, "Any unused wires should be taped out of the way." Although the person who wrote thes~ instructions intended for the wires to be individually taped out of the way, they were folded back as a*

group and taped out of the way .. Thus, the "e~tra" wires ended.up electrically contacting each other and created short circuits across several independent

• electrical schemes when the cables from the DAS were incorrectly connected to the sequencer test jacks. Those electrical short circuits combined with the incorrect te~t cable connection to activate the left channel OBA sequencer which caused the actuation of the LPSI pump P~67B and containment Air Cooler Fan V-4A. .

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. CORR(CTIVE ACTION

1) Revise procedures RT~l3A ~nd B and RT~8C and D to add sufficient deiail to ensure a proper connection b~tween the DAS and the plant sequencers.

2) Revise the labeling of the cable test plugs *nd add labels to the

. sequencer test jacks to b~ consistent with pl~nt drawings~

3) Revise plant drawings to identify all wires in the test cables and tlieir associated termination point in the test cable plugs.

ADDITIONAL INFORMATION None

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