ML20029C706

LER 94-001-00:on 940323,missed Surveillance on SRV Low-Low Set Logic.Caused by Incorrect Surveillance Procedure Prerequisite.Corrective Action:Removed Incorrect Prerequisites,Trained on Procedure review.W/940422 Ltr

ML20029C706
Person / Time
Site:	Monticello
Issue date:	04/22/1994
From:	Richard Anderson, Parker T NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-001-01, LER-94-1-1, NUDOCS 9404260358
Download: ML20029C706 (5)

Text

Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 554011927 Telephone (612) 330-5500 I

April 22, 1994 Report Required by 10 CFR Part 50, Section 50.73 (a)(2)(1)

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Missed Surveillance due to Procedural Error The Licensee Event Report for this occurrence is attached. This report contains the following new NRC commitments:

1. The plant administrative directive that provides guidance on review of procedures will be revised to add guidance on review of prerequisites.

2. Training on the procedure review and temporary change processes will be provided to the engineering staff at a future Engineering Technical Staff Training session.

Please contact Terry Coss, Sr Licensing Engineer, at (612) 295-1449 if you require further information.

1cC?

.Ro er O Anderson Director Licensing and Management Issues c: Regional Administrator - III NRC Sr Resident Inspector, NRC  ;

NRR Project Manager, NRC '

State of Minnesota, Attn: Kris Sanda Attachment q

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MODE (9) N 20 402(b) 20.405(c) 50 73(a)(2)(ivl 7311(b)

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~dbSTRACT (Lirnit to 1400 spaces, i es approximately 15 sinhe-spaced typeWntten hnes) (16)

A missed surveillance on the SRV Low-Low set Logic was discovered while performing verification of the Reactor Pressure Relief System design basis document. The surveillance procedure contained incorrect prerequisites.

During a reactor shutdown, the surveillance procedure was not performed as the procedural prerequisites were not met. Following discovery of the error, the '

surveillance was successfully completed at power using a special procedure.

The surveillance procedure has been revised.

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EXPlRES 5/31/95 ESTtMATED BURDEN PER RESPONSE TO COMPLY WrTH THis INFORMATION COLLECToN REQU 50 0 HRS. F ORW ARD LICENSEE EVENT REPORT (LER) CouutNTs REoiRoNo BunoEN EES,T: 7uATE TO TsE NroRuAroN TEXT CONTINUATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714L U S. NUCLEAR REovuTonY couu1SSoN. wASwwaTON, oC rossswot ANo to THE PAPERWORK REDUCTON PRCUECT (31540104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503 F ACluTY NAME (1) DOC 9tET NUMBER (2) Lf R NUMBER (s) PAGE (3) gg SEQUENitAL REVI3oN NUMBE R NUMBER 05000 - 263 OF Monticello Nuclear Generating Plant 94 - 001 -

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Description:

On March 23, 1994, with the plant operating at 100% power, a missed surveillance on the SRV Low-Low Set Logic was discovered. While performing verification of the Reactor Pressure Relief System design basis document, it was discovered that the Reactor Scram sensing portion of the Safety / Relief Valve Low-Low set Logic surveillance was not done as required during a shutdown on July 31 and August 1, 1993.

The Technical Specifications for the Reactor Scram sensing require a test frequency of "Once/ Shutdown (Note 8)" where Note 8 states "Once/ shutdown if not tested during previous 3 month period."

During the subsequent startup on August 1, 1993, this surveillance was not' performed as the prerequisites for the surveillance procedure were not met.

The prerequisites were incorrect and the test should have been performed.

This was discovered on March 23, 1994. Special procedures were approved to perform this test at power. These special procedures were successfully performed on March 23 and 24, 1994.

Cause:

The cause of the missed surveillance was an incorrect surveillance procedure prerequisite. The Technical Specification requirement for this surveillance procedure was issued on November 16, 1984. The test was first performed on January 4, 1985. In December, 1987, the prerequisite was incorrectly revised to state that (the underlined part was added):

Plant in shutdown or refuel mode,_ reactor pressure < 110 osio and temperature < 345 Jde._greesi F.

This is not a valid prerequisite for this surveillance. The prerequisite was-included in this surveillance procedure with the addition of other Low-Low Set surveillances to this procedure. This was a cognitive error during the procedure revision.

During the August 1993 shutdown, the plant did not go below 110 peig and 345 degrees F and the surveillance was not done because the prerequisites were not met.

NRC FORht 26A (5 92)

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SEQUENT;A;. REv$0N yg NUMBER NUMBER 05000 - 263 OF Monticello Nuclear Generating Plant 94 - 001 -

00 3 4 rw m n. n.c. ., ,,w.a a .xw. co., a wc m xs o n During the review of all shutdowns since December, 1987, which was initiated following the discovery of this missed surveillance, it was determined that the surveillance procedure had been temporarily changed to eliminate the incorrect prerequisites on two separate occasions by operations personnel.

The first of these temporary changes tassociated with a December 16, 1988 shutdown) was incorrectly interpreted during review and identified as a non-permanent change. No subsequent action was taken to incorporate the change permanently into the procedure. Administrative controls on temporary changes have been revised since then. The permanency decision for temporary changes is now better scrutinized. It is unlikely that a similar repeat error will occur.

The second temporary change (associated with an April 20, 1992 shutdown) was identified as a permanent change to the procedure and slated for immediate incorporation into the existing procedure. However, this procedure was in the revision process at that time. The revision consisted of separating the surveillance that is the subject of this report from other surveillances on Safety / Relief Valve Low-Low Set and making it a separate surveillance procedure. The person making the revision was notified to incorporate the temporary change. A document change notice was also placed in the existing procedure's file, giving notice to potential users of the temporary change.

This notice stated that it was only applicable to the current revision since the surveillance requirement to which the temporary change applied was being removed in the new revision. The temporary change was not incorporated into the newly created procedure due to cognitive personnel error.

Analysis:

The failure to do a surveillance is a violation of the Monticello Technical Specifications and is being reported under 10 CFR Part 50, 50.73(a)(2)(1)(B).

The function of the Low-Low Set System is to minimize the possibility of a safety / relief valve reopening while an elevated water leg is in its discharge line. The logic invokes lower setpoints for three of the Safety / Relief valves following a scram. In Low-Low Set, the system pressure blowdown range is larger (80 psi) and a time delay prevents the valve from reopening for 10 seconds. Following valve closure, the steam in the discharge line condenses and draws torus water up into the discharge line. A vacuum breaker opens to allow the water to drain to torus water level. If the Safety / Relief valve were to reopen with an elevated water leg in the discharge line, damage could 1 be done to the Safety / Relief valve discharge line or torus. The 10 second delay time is sufficient time for the discharge line to drain to torus water level. Each of the three Safety / Relief valves can be opened by either of two independent trains of logic.

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YEAR NUMBER NUMBfR 05000 - 263 OF MOnticello Nuclear Generating Plant 94 001 00 4 4 Tus p n, an.co v.w.a a. euw. cap.., or wc nm, xs o n Prior to discovery of this event, the Reactor Scram sensing portion of the SRV Low-Low Set Logic was last tested on March 16, 1993. Upon discovery of the missed surveillance, it was promptly performed on March 23 and 24, 1994. The logic was tested satisfactorily.

The scram sensing portion of the SRV Low-Low Set Logic is very reliable and has never failed this surveillance test. Had a failure of a relay occurred between August 1993 and March of 1994, no inoperability would have occurred as one relay failure would affect only one division of the Low-Low Set Logic.and the system would still have performed as designed.

Corrective Action:

1. The Reactor Scram sensing surveillance of the SRV Low-Low Set Logic was successfully completed on March 23 and 24, 1994.

2. The Reactor Scram sensing surveillance procedure was revised to remove the incorrect prerequisite.

3. The plant administrative directive that provides guidance on review of procedures will be revised to add guidance on review of prerequisites.

4. Training on the procedure review and temporary change processes I will be provided to the engineering staff at a future Engineering Technical Staff Training session.

S. A review of other Technical Specification required surveillance  !

tests was conducted. All surveillance procedures not routinely scheduled were reviewed for the last ten years. No other problems were identified in this review.

Additional Informatical Failed Component Identification NONE Previous Similar Event: NONE NRC FOMM 366A (S-97)

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