ML20011E225

LER 86-032-01:on 860802,inadvertent Start of High Pressure Injection Pump 1-2 Occurred.Caused by Open Relay Coil. Failed Relay Replaced & Procedure Change Initiated. W/900130 Ltr

ML20011E225
Person / Time
Site:	Davis Besse
Issue date:	01/30/1990
From:	Storz L, Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-86-032, LER-86-32, NP33-86-032, NP33-86-32, NUDOCS 9002090318
Download: ML20011E225 (4)

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-January 30, 1990 Log No.:' BB90-00071 NP33-86-032, Rev. 1

,, Docket No'. 50-346  :

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United States Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555 ,

l Gentlemen:

LER 86-032, P.evision 1 Davis-Besse Nuclear Power Station, Unit No. 1 Date of Occurrence - August 2, 1986  ;

Enclosed please find revision 1 to Licensee Event Report 86-032. The revisions are. indicated by a revision bar in the leftJhand margin. This

• revision deleted Facility Change Request (FCR)86-265 as.one of the corrective -l actions.- Please discard or mark superseded any previous copies of this LER.

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L Louis F. Storz L- Plant Manager Davis-Besse Nuclear Power Station LFS/plf Enclosure Mr. A. Bert Davis L cc Regional Administrator USNRC Region III

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Hr. Paul Byron DB-1 NRC Sr. Resident Inspector

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, TITLE tot Safety Features Actuation System Start of the High Pressure Injection Pump i SVENT DATE (S) LER NUMBER (4) REPORT DAf t (7) OTHER F ACILITit$ INVOLytD (8) ,

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l l l I l l l SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR SUDMi&$10N YES !!! yes corne,en EX9tCTfD SUO4 cts 3 ION DA Til NO l l l As:T uCT m, <, M mo - u. e , ,,,,,n,, ,,, ,, ,,,,,... ,v, ,,,,,,, ,,,,,, n .1 On August 2, 1986, at 1229 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.676345e-4 months <br />, while in Mode 5, during the performance of the Safety Features Actuation System (SFAS) Honthly Test, ST 5031.01, an inadvertent start of the High Pressure Injection (HPI) Pump 1-2 occurred. The test was being performed on SFAS Channel 4. A failed output relay in Channel 2 caused the pump to start when a half trip signal was produced in Channel 4 as a normal part of the test. This part was replaced and the test was ccmpleted.

The SFAS relays are designed to fail in the safe (tripped /de-energized) state, and a concurrent trip of the complimentary SFAS channel vill cause a full trip of SFAS. The SFAS testing takes this into account by utilizing status (data) ,

lights which the operator observes the complimentary SFAS relay state prior to performing a half trip for the tested channel. However, due to an HPI pump test being performed concurrently, these indications were masked.

Although the actual failure was a random component failure which is l.

unavoidable, a procedure change to ST 5031.01 was made to prevent inadvertent actuation due to inability to observe data lights. Additional training was given to test personnel on data light operation.

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UCENSEE EVENT F.EPORT (LER) TEXT CONTINUATION EXPentl. S/3i/W Fatakaty esaast us pocetag nyesseR tal Paos (si

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0 l1 0 l2 or 0 l3 tortame. eme-w. .ess.wmics ama m Description of Occurrence:-

Licensed Operations personnel vere performing the Safety Features Actuation ,

l System (SFAS)(JE) Honthly Test, ST 5031.01, on SFAS Channel 4. .This test verifies _setpoints as well as half trips of output (actuation) modules and status indication features. One of the precautions in the procedure is to verify from data lights on the front of the cabinet that no abnormal conditions exist prior to proceeding with the test. The operation of these lights is described in detail in ST 5031.01.

During plant shutdown, there are numerous components which may give data light indications which are not standard due to maintenance activities or testing in l=

progress. Due to the testing which was in progress on High Pressure Injection (HPI) Pump 1-2,-the pump was being run at-the start of ST 5031.01, the HPI pump testing ended and the pump was stopped. When the Channel 4 module was tripped (for the second time in the test) the HPI pump started. The pump start was immediately recognized by the Control Room Operator who blocked the Channel 4 output module and stopped the pump. No injection occurred since HPI is isolated per procedure in Mode 5.

Investigation performed immediately following the pump initiation found the SFAS Channel 2 output relay for the HPI pump tripped (de-energized). This relay was replaced under Maintenance Work Order (MWO) 1-86-2789-00. ST 5031.01, which.vas suspended when the HPI Pump 1-2 started, was performed to demonstrate correct relay operation following replacement.

This event occurred while the plant was in Mode 5 at 1229 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.676345e-4 months <br /> on August 2, 1986. Immediate notification was made per 10CFR50.72(b)(2)(ii) due to this being an Engineered Safety Features (ESP) Actuation. This report is being submitted per 10CFR50.73(a)(2)(iv).

Apparent Cause of Occurrence:

Relay coil of Deutsch 4CP36AF (CCC P/NKE N431A) opened causing th'e relay responsible for the SFAS start of the HPI Pump 1-2 from Channel 2 to de-energize. When the SFAS Channel 4 complimentary relay was de-energized as part of ST 5031.01, the pump started.

This condition would have been observable prior to start of ST 5031.01, however, testing being performed concurrently on HPI Pump 1-2 masked indication from the operators.

Analysis of Occurrence:

As the cause of the HPI pump actuation was an isolated single component failure, no other systems or components were affected. This actuation would

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not have prevented any safety systems from performing their intended functions. Even with the component failure, the operator still had-the capability to control the subject equipment as demonstrated by the blocking '

and stopping of the pump following the inadvertent actuation. A relay failure of this type vill not prevent SFAS from doing its safety function.

Corrective Action to Prevent Recurrence:

Output relays utilized in the SFAS are highly reliable. .Although there have been several relay failures within the past year, this represents less than a one percent failure rate of the hundreds of relays in the SFAS. As major modifications have been performed in the SFAS during the current outage,'there  ;

have been several de-energizations of the channels.- Some component failures are to be expected due to the transient effects of turning power supplies on and off numerous times. i The failed relay was replaced under MVO l-86-2786-00. In addition to component replacement, a procedure change was prepared to limit concurrent l testing performed while ST 5031.01 is in progress and to provide additional  ;

precautions to prevent recurrence.

Finally, training was given to personnel who perform this type of testing to reflect lessons learned from this event. This was prior to the next use.

Failure Datas

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Under the present'10CFR50.73, there were five LERs in 1984 and seven LERs in

! 1985 for unplanned ESF actuations. In 1986, there have been two unplanned ESF L

actuations. In 1986, there have been two unplanned ESF actuations; see LERs 86-08 and 86-16.

REPORT NO.: NP33-86-42 PCAO No. :'86-220 - l

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