ML20006E686

LER 90-001-00:on 900118,reactor Protection Sys Channel 2 Bypassed Temporarily During Performance of DB-MI-03207. Caused by Inadequate Procedure Re Inoperable Channel Removal.Procedure SP1105.02 revised.W/900220 Ltr

ML20006E686
Person / Time
Site:	Davis Besse
Issue date:	02/20/1990
From:	Storz L, Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-001, LER-90-1, NP-33-90-001, NP-33-90-1, NUDOCS 9002260212
Download: ML20006E686 (4)

Text

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M80N EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652-0001 February 20, 1990 Log No.: BB90 00183 ,

NP33 90 001 Docket No. 50 346 License No. NPF 3 United States Nuclear Regulatory Commission '

Document Control Desk Washington, D. C. 20555 ,

Gentlemen:

LER 90-001 Davis Besse Nuclear Power Station, Unit No. 1 Date of Occurrence - January 18. 1900 l

Enclosed please find Licensee Event Report 90 001, which is being submitted to provide 30 days written notification of the subject occurrence. This LER is being submitted in accordance with 10CFR50.73(a)(2)(1).

Yours truly,

, e L S

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Louis F. Storz Plant Manager Davis Besse Nuclear Power Station LFS/p1f Enclosure cc: Mr. A. Bert Davis Regional Administrator USNRC Region III Mr. Paul Byron DB-1 NRC Sr. Resident Inspector D / ' l 90o226o212 9oo22o j PDR ADOCK o50o0346 S

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~} Tts tu a.v a.w." evecreo suostissroov carts T} NO l l l A=TW:CT ru ,. ,m ,. . ,,.. ,, ,,n e.,w e er-r a , nei On January 18, 1990, at 0919 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.496795e-4 months <br />, Reactor Protection System (RPS) Channel 2 was bypassed for about one minute during performance of DB MI-03207, the Reactor Coolant Pump (RCP) Monitor Inputs to RPS and Steam and Feedwater Rupture Control System (SFRCS). Since RPS Channel 2 had been declared inoperable and placed in a tripped condition on January 12, 1990, the bypassing is a violation of the action statement of Technical Specification 3.3.1.1. The cause was an inadequate procedure which did not caution against removing an inoperable channel from its tripped condition. Recognizing that the procedure did not provide specific instruction for performing this test on a tripped channel, the RPS Operating Procedure, SP1105.02, was consulted. However, an error in the wiring schematic in the procedure mislead the operator to expect that the channel would not reset. The channel was retripped within one minute of the bypassing. Later the same day, the NRC approved discretionary enforcement which e.11 owed Toledo Edison to remove RPS Channel 2 from the tripped condition for the remainder of the operating cycle. The four procedures which test the RCP monitor inputs to RPS and SFRCS will be changed to prevent removing an inoperable channel from the tripped condition and thus prevent violation of the action statement. Other safety system instrumentation procedures are being evaluated for the need for a similar precautionary statement.

The schematic used as an operator aid in the RPS cabinets and in Operating Procedure, SP1105.02, have been eliminated.

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On January 18, 1990, at 0919 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.496795e-4 months <br />, the Reactor Protection System (RPS JC) Channel l 2 was inadvertently bypassed for about one minute during performance of j DB MI-03207, Char.nel Functional Test and Calibration of RCP Monitor Inputs to SFRCS l ACH2 and RPS Channel 2. The RCP Monitor is the Reactor Coolant Pump (RCP) current monitor which senses whether each RCP is on or off and provides an input to the j

Steam and Feedwater Rupture Control System (SFRCS JB) and RPS. RPS Channel 2 had 1 previously been declared inoperabic on January 12, 1990, when a Reactor Coolant i System (RCS-AB) flow transmitter drifted high out of tolerance. Channel 2 was placed in the tripped condition at that time in compliance with the action statement of Technical Specification 3.3.1.1. Removing the inoperabic channel from the tripped condition to perform this test is a viointion of the action statement.

• This event is reportable as an LER utder 10CFR50.73(a)(2)(1)(3) as a condition prohibited by Technical Specifications.

As part of the review of this event, it was discovered that a similar event occurred on September 23, 1989. In that event, a different flow transmitter failure had caused RPS Channel 2 to be declared inoperable and placed in the tripped condition. During testing, the technician manually bypassed the channel

.mer directions in the procedure.

(ggirent Cause of Occurrence:

ine cause of the action statement violation was an inadequate procedure, DB-MI-03207, which did not provide precautions when performing the test on an inoperable and tripped channel. It should have cautioned against placing such a channel in bypass. Since the procedure did not provide direction for this condition, the RPS Operating Procedure, SP1105.02, was consulted. But due to an error in a schematic in this procedure, the operators were misled to believe that the channel would remain tripped during the test. The schematic incorrectly showed the tie-in point for the manual bypass circuit to be above the reset switch, but in fact, it is below it. Therefore, when the first step in the procedure section of DB MI.03207 was performed, the channel was removed from the tripped condition which violated the action statement.

Annivsis of Occurrence:

Bypassing of the channel places the RPS in a two out of three trip logic rather than a one out of three to trip (with one channel already tripped). Having the inoperable channel bypassed for about one minute has no safety significance. RPS g,o un .v s o.o me o enessasii

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Channel 2 was declared inoperable on January 12, 1990, when an RCS flow transmitter i drifted high out of calibration specifications. The bistables for the other seven s parameters sensed by this RPS Channel were operable. Therefore, when Channel 2 was bypassed, RPS was in a two out of three logic.

The NRC did approve discretionary enforcement later in the day on January 18, 1990, to allow Davis-Besse to reset Channel 2 for the remainder of this operating cycle with the flow transmitter out of tolerance (the Sixth Refueling Outage was scheduled to start February 1, 1990).

Corrective Action:

The four procedures (DB MI 03205, 03206, 03207, and 03208) that test the RCP monitor inputs to the four RPS channels and the four SPRCS channels will be changed to include precautions against removing an inoperable channel from the tripped condition. Thesa procedure changes will be completed before startup from the present refueling outage. Other safety system instrumentation procedures are being evaluated for the netad for a similar precautionary statement.

On February 4, 1990, a decision was made to eliminate the schematic as an operator aid and as an attachment to SP1105.02 (DB-CP 06403). The schematic was removed from the RPS cabinets on February 14, 1990. The change C90 1073 to SP1105.02 (DB 0P 06403) was approved February 15, 1390.

Failure Data:

This is the first report of an inoperable RPS channel being removed from its tripped condition in violation of the action statement. It is now recognized that a similar event occurred on Septen.ber 23, 1989. The only previous report of an inoperable safety system instrumentation function being removed from'the tripped condition in violation of its action statement was LER 87-002. A Safety Features Actuation System (SFAS) Channel I containment radiation trip module was bypassed during post maintenance testing in violation of its action statement. In that

-incident, a technician failed to follow the requirements of the prerequisites of the procedure. The corrective action was counseling of the technician to adhere to procedures. The action would not have prevented the January 18, 1990, event since they involve different causes.

REPORT NO.- NP33 90-001 PCAO No.:90-0022 gge o.. .o .v s oao u se-oe:4-ab4si