ML20207Q993

Special Rept 1-SR-87-005:on 870108,radiation Monitoring Units RU-145 & 146 Il Found Inoperable Due to Closed Inlet Valve HCV01.Valve Opened Immediately & Similar Valves Verified to Be in Correct Position.Procedure Revised

ML20207Q993
Person / Time
Site:	Palo Verde
Issue date:	02/23/1987
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
1-SR-87-005, 1-SR-87-5, ANPP-00149-JGH, ANPP-149-JGH, NUDOCS 8703100374
Download: ML20207Q993 (2)

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Arizona Nuclear P.O. box 52034 Power e PHOENIX, ARIZONA ProJFdtM8 '2 g /*

85072-2034 ANPP-00 GH/TDS/ ESP-96.03 February 2 , AQ 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 Unit 1 Docket No. STN 50-529 (License NPF-51)

Special Report 1-SR-87-005 File: 87-020-404

Dear Mr. Martin:

Attached please find a voluntary Special Report 1-SR-87-005 prepared and submitted pursuant to Technical Specifications 3.3.3.1 and 6.9.2. This report discusses a Radiation Monitoring Unit Inoperable Due to a Closed Valve.

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

Very truly yours,

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J. G. Haynes Vice President Nuclear Production JGH/TDS/ ESP /cid Attachment cc: O. M. DeMichele (all w/a)

E. E. Van Brunt, Jr.

R. P. Zimmerman R. C. Sorenson E. A. Licitra A. C. Gehr INPO Records Center i

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PALO VERDE NUCLEAR GENERATING STATION Voluntary Special Report 1-SR-87-005 Radiation Monitoring Unit Inoperable Due to Closed Valve Docket No. STN-528 License No. NPF-41 This special report is submitted voluntarily to describe an event which occurred on January 8, 1987.

At 0820, on January 8, 1987, Palo Verde Unit 1 was in Mode 1 (POWER OPERATION) at 100% rated thermal power when a Radiation Protection Technician (contractor non-licensed) discovered the inlet valve (HCV01) closed on Radioactive Gaseous Effluent Monitors (RU-145/146)(IL) in the Fuel Building ventilation system. The closed inlet valve caused the particulate / lodine sample media and the Noble Gas Activity Monitor to be isolated from the process flow path. This rendered the monitor inoperable. The closed inlet valve was immediately opened restering operability.

With the inlet valve shut a low flow alarm should have actuated to alert the on duty technician of the improper valve position. A work order was issued to troubleshoot and/or rework the monitor to correct the problem with a no low flow alarm when the inlet isolation valve is closed. Leaks were found around the sample holders and pipe fittings, which allowed a sufficient amount of air to enter the monitor and inhibit the low flow alarm.

As an immediate corrective action, other similar Unit 1 Radiation Monitoring inlet valves were verified to be in the correct position. Additionally, the leaking fittin8s were tightened and the sample holder correctly adjusted to stop the leaka80.

An investigation was conducted to determine the cause of the closed valve and establish a time of occurrence. A review of work activities revealed that no work activities had been conducted which involved the closure of this valve. Therefore the cause and time of the closure of the closed valve could not be determined. In accordance with the guidance provided in Section 14.0 of NUREG 1022 (Supplement 1), PVNGS has assumed the event occurred at the time of discovery. The radiation monitors were restored to operability within the requirements of the applacable Action Statement as discussed above. However, since the possibility of having exceeded the Action Statement exists and since PVNGS considers this event of sufficielt importance, this report is submitted voluntarily for NRC information.

As corrective action to prevent recurrence, a rryision to the weekly sample change out procedure to include verification of a low flow slarm after the samples have been changed, has been initiated. Also, procedures used for particulate / iodine sample media change out Trill be revised to include specific alignment verifications prior to placing a monitor bsck in service.

Since no spent fuel is currently in tijp fuel pool and RU-19, the spent fuel pool monitor, was operable throughout the event, th;s event had no impact on the safe operation of the plant.

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