ML20205G007

Special Rept 2-SR-86-018:on 860705,reactor Vessel Water Level Sys Inoperable for More than 7 Days.Caused by Connection of Channel B Heated Junction Thermocouples in Reverse Order.Connection Corrected

ML20205G007
Person / Time
Site:	Palo Verde
Issue date:	08/06/1986
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
2-SR-86-018, 2-SR-86-18, ANPP-00043-JGH, ANPP-43-JGH, NUDOCS 8608190379
Download: ML20205G007 (2)

Text

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Arizona Nuclear Power Project P O. BOX 52034 e PHOENIX, ARIZONA 85072-2034 August 6, 1986 ANPP-00043-JGH/TDS/DW-96.03 Mr. John B. Martin, Regional Administrator Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 2 Docket No. STN 50-529 (License NPF-51)

Special Report-2-SR-86-018 File: 86-020-404

Dear Mr. Martin:

Attached please find Special Report (2-SR-86-018) prepared and submitted pursuant to Technical Specifications 3.3 3.6 and 6.9.2. This report discusses the inoperability of one channel of the reactor vessel water level system for a period of greater than seven (7) days.

If you have any questions, please contact T. R. Bradish, Compliance Supervisor at (602)932-5300 Ext. 6936.

Very truly yours,

. G. Hayfus (m

Vice President Nuclear Production JGH/DW/dh Attachment cc: 0. M. DeMichele (all w/a)

E. E. Van Brunt, Jr. 3M R. P. Zimmerman A. L. Hon .

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A. C. Gehr INP0 Records Center 09:4 448b d 8608190379 860806 9 >

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PALO VERDE NUCLEAR GENERATING STATION UNIT 2 Channel B Reactor Vessel Water Level System Inoperable License No. NPF-51 Docket No. 50-529 Special Re~ port 2-SR-86-018 l Pursuant to Post Accident Monitoring Instrumentation Technical Specification i 3 3 3.6 Table 3 3-10, ACTION STATEMENT 31, this submittal provides the h

required Special Report for the inoperability of one Channel of the reactor vessel water level system for a period of greater than seven (7) days.

On July 5, 1986, with Palo Verde Unit 2 in Mode 5 (COLD SHUTDOWN), the reactor coolant system (RCS) was being drained to support maintenance.

l During this evolution, the Channel B indication for reactor vessel water level, provided by the Qualified Safety Parameter Display System (QSPDS), was observed to be operating abnormally. Channel B was indicating a level decrease from the vessel plenum area first, instead of from the vessel head area (Channel A QSPDS indicated normally). Since the reactor vessel level

indication was not required in Mode 5, no immediate action was necessary and l a work request was generated to investigate the problem.

I Each Channel of the reactor vessel level system utilizes eight (8) heated l junction thermocouples (HJTC) to generate the signals for the 8 indicated /

( levels. On July 14, 1986, troubleshooting determined that the Channel B HJTC /

l were connected in reverse. This error had apparently occurred because the J-l identification tags on the associated HJTC cables are numbered in reverse order of the HJTCs. That is, HJTC cable #1 connects to HJTC #8. This numbering system is per design drawings, but may have resulted in confusion when the cables were connected. The cables were subsequently correctly connected on July 16, 1986.

The Channel B reactor vessel level system had been verified to operate

! correctly during initial RCS fill. Since that time, the only system maintenance which could have resulted in the reversed connections was performed in February 1986. Although the reversed connections rendered-

Channel B inoperable, this had not been detected since the RCS was not l drained at that time. There are no safety implications associated with this i event since Channel A was operable at all times, satisfying the minimum l channels required to be operable in accordance with Table 3 3-10.

l To prevent recurrence of this event, an Engineering Evaluation Request has i been submitted which will renumber the identification cable tags to coincide with the HJTC numbers.

l

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