ML20217D188

Advises of Change in Status of Commitment Re Reorientation of Eight Target Rock Valves During Fifth Refueling Outage

ML20217D188
Person / Time
Site:	Wolf Creek
Issue date:	05/13/1991
From:	Withers B WOLF CREEK NUCLEAR OPERATING CORP.
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20217D178	List: ML20217D175 ML20217D188
References
NUDOCS 9107220086
Download: ML20217D188 (2)

Text

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l WOLF CREEK NUCLEAR OPERATING CORPORATION Bart 0 W1mers m w ano May 13, 1991 cw Execueve cee.

VM 91-0051 R. D. Martin, Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011

Reference:

Letter dated July 5, 1990 from S. J. Collins, NRC to B. D. Vithers, VCNOC

Subject:

Docket No. 50-482: Change in Consnitment Dear Mr. Martin The purpose of this letter is to advise the NRC of a change in the status of a

commitment made in the Reference. The cotanitment concerned the reorientation of eight Target Rock valves during the fifth refueling outage. As discussed below, the reorientation of two of the eight valves is being postponed to the sixth refueling outage. This change in commitment was discussed with the NRC Resident Inspector on March 11, 1991.

On May 2, 1990 BG BCV-8357B (reactor coolant pump seal injection valve) failed open. Valve had been made to replace BG BCV-8357A had previously failed open and preparations this valve when 8357B failed. These valves are Target Rock pilot assisted solenoid operated valves. Evaluation of the failures identified that air or vapor displaced the water above the valve disk in the pilot portion of the valve when the system was drained during the last refueling outage. The valves were replaced and installed with the solenoids below the system pipe. This modified installation is expected to prevent when _

the water from draining system is draired.

out of the pilot portion of the valve operator additional valves installed in theFurther plant evaluation identified eight requiring the modified installation. A verbal commitment to reorient these eight valves during the fifth refueling outage was made to the NRC Resident Inspector and documented in Inspection Report 50-482/90-22 dated July 5, 1990.

During.the the eight valves, development of the plant modification to support reorientation of it was identified from design drawings that valves BB HV-8002 due to potential A and B (reactor vessel head vent valves) could not be reoriented interferences. Field walkdown of these valves during an outage is necessary in order to complete the design modification.

9107220086 910715 PDR ADOCK 05000482 P PDR PC. Box 411/ Burnngton, KS 66839 / Pnone:(316) 364-8831 An Eaue opportsey Erremyw MF44CNET

6, VM 01-0051 Page 2 of 2 The reactor vessel head vent system functions to remove air, noncondensable gases, and steam from the reactor vessel head under certain conditions. The system consists of two redundant vent paths each containing two solenoid valves in series. A review of the failure mechanism identified that the conditions that could cause a failure of the reactor vessel head vent valves are limited. The two normally closed valves in series lLnit any postulated events which could result in an inadvertent opening of the head vent.

Additionally, an orifice is installed in each vent path which is designed to limit flow to within the capacity of one centrifugal charging pump in the event of a ruptured vent line or an inadvertent opening of the vent valves.

Based upon the above discussion, valves BB HV-8002A and B will be reoriented prior to star cap f rom the sixth refueling outage.

If you hr e any questions concerning this matter, please contact me or Mr. H. K. Chernoff of my staff.

Very truly yours, Bart D. Withers President and Chief Executive Officer BDW/jra cci A. T. Howell (NRC)

L. L. Gundrum (NRC)

D. V. Pickett (NRC)

Document Control Desk (NRC)

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