05000302/LER-1983-031, Supplementary LER 83-031/03L-1:on 830725,containment Isolation Valve CAV-6 & -7 Would Not Close Under Sys Pressure of 1,000 Psi.Caused by Insufficient Design &/Or Inadequate Maint Procedures

Supplementary LER 83-031/03L-1:on 830725,containment Isolation Valve CAV-6 & -7 Would Not Close Under Sys Pressure of 1,000 Psi.Caused by Insufficient Design &/Or Inadequate Maint Procedures

ML20077N509
Person / Time
Site:	Crystal River
Issue date:	09/07/1983
From:	Hughes P, Westafer G FLORIDA POWER CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
3F-0983-05, 3F-983-5, LER-83-031-03L, LER-83-31-3L, NUDOCS 8309130153
Download: ML20077N509 (4)

LER-2083-031, Supplementary LER 83-031/03L-1:on 830725,containment Isolation Valve CAV-6 & -7 Would Not Close Under Sys Pressure of 1,000 Psi.Caused by Insufficient Design &/Or Inadequate Maint Procedures

Event date:
Report date:
3022083031R00 - NRC Website

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SUPPLEMENTARY INFORMATION REPORT NO.: 50-302/83-031-03L-1 FACILITY: Crystal River Unit 3 REPORT DATE: September 7,1983 OCCURRENCE DATE: July 25,1983 IDENTIFICATION OF OCCURRENCE:

Containment isolation valves CAV-6 and 7 will not stroke fully closed under system pressure of 1,000 psi. This failure is being reported in accordance with Technical Specification 6.9.1.9(b).

CONDITION PRIOR TO OCCURRENCE:

Mode 3 (Hot Standby)

DESCRIPTION OF OCCURRENCE:

On July 25, 1983, personnel discovered a slight packing leak on CAV-7, steam generator "B" secondary sampling valve. The packing was tightened, and the leak was stopped. The valve was then stroked successfully to the fully closed position. Personnel recognized that the evolution must also be timed; the valve was stroked again. The valve failed this test (0710 on July 25,

-1983). The packing was loosened, and the valve still failed to stroke fully closed.

The penetration was isolated using CAV-5, and maintenance was initiated. When repair personnel tested CAV-7, with CAV-5 isolated, they found the valve to be operable. Thus, at 0630 on July 26,1983, CAV-7 was declared operable. CAV-5 was opened, and the penetration returned to its normal configuration.

With CAV-5 open, at 0730 on July 26,1983, CAV-7 again failed to stroke fully closed against system pressure of 1,000 psi. The valve was declared inoperable, and the penetration was isolated once again.

- Later, at 0845, CAV-6, steam generator "A" secondary sampling valve, also failed to stroke fully closed. CAV-6 was isolated using CAV-4.

DESIGNATION OF APPARENT CAUSE:

The failures of CAV-6 and 7 to stroke fully closed in these events were caused by insufficient design assumptions and/or overtightening the valve packing.

CAV-6 and 7 are actuated by a spring. This spring produces 750 pounds of force when compressed and 500 pounds of force when the valve is closed. Calculations indicated that for a significantly large coefficient of friction, this spring cannot close this valve at a system pressure of 1,000 psig.

Apparently, the design of this valve considered a smaller coefficient of friction or system pressure than is actually there. The coefficient of friction is directly proportional to the tightness of the valve packing. Thus, these failures could have been caused by inadequate design assumptions or maintenance practices.

i ANALYSIS OF OCCURRENCE:

While not capable of closing under normal system pressure of 1000 psi, these valves are capable of closing against 50 psig. This is the highest pressure these valves must close against to satisfy the assumptions made in the safety analysis for reactor building isolation. Therefore, these valves are capable of fulfilling their intended safety functions.

CORRECTIVE ACTION:

The affected penetrations have been isolated. A stronger spring will be installed in these valves during the next outage of sufficient duration.

FAILURE DATA:

This is the third reported failure for CAV-6 and the first for CAV-7.

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Power C0APOAAfs0as September 7,1983 3F-0983.05 Mr. James P. O'Reilly Regional Administrator, Region II Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission 101 Marietta Street N.W., Suite 2900 Atlanta, GA 30303

Subject:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Licensee Event Report No.83-031

Dear Mr. O'Reilly:

Enclosed is Licensee Event Report No. 83-031/03L-1 and the attached supplementary information sheet, which are submitted in accordance with Technical Specification 6.9.1.9(b). This report supplies supplementary information to our initial report dated August 24,1983.

Should there be any questions, please contact this office.

Sincerely,

/  !

G. R. Westafer Manager Nuclear Operations Licensing and Fuel Management AEF:mm Enclosure cc: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D.C. 20555 __, _

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General Off;ce 3201 Tnerty fourtn street soutn. P O. Box 14042 st. Petersburg. Florida 33733 e 813-.-866-5151