ML20084D225

AO 50-237/75-32:on 750526,electromagnetic Relief Valve 203-3B Failed to Open During post-maint Testing of Valves. Cause Unknown.Corrective Actions to Be Determined When Cause Discovered

ML20084D225
Person / Time
Site:	Dresden
Issue date:	06/03/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
339-75, 6373, AO-50-237-75-32, NUDOCS 8304110010
Download: ML20084D225 (3)

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,j /r C ,') One Fer: honal P!ars. Ch.cago. Uhnoiy ^ /

Addres ply to: Post Othcc Box 767 's

Chicago, !!!inois 60690 BBS Ltr. #339-75 Droaden Nuclear Power Station R. R. #1 '

Morris, Illinois' 60450 June 3, 1975 4

Mr. James G. Keppler, Regional Director Directorato of Regulatory Operation-Region III U. S. Nuclear ReCulatory Commission 799 Roosevelt Road '

Olen Ellyn, Illinois 60137

SUBJECT:

REPORT OF AF!ORAL OCCURREiCE FER SECTION 6.6.A OF THE TECmiICAL SPFI IFIC ATIC:!S 2-203-331~LECTRO:1 TIC RELIEF VAUIE FAILURE Roforences: 1) Regulatory Guide 1.16 Rev.1 Appendix A

2) Notification of Region III of U. S. Nuclear Regulatory Co::raicsion Telephone: Mr. Knop, 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on 167 26, 1975 Telegram: Mr. Keppler, 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br /> on May 27, 1975

3) Drawing Number M-12 Report Number: 50-237/75-32 Report Date: June 3, 1975 .

Occurrence Date: Ihy 26, 1975 Facility: Dresden Nuclear Power Station, Morris, Illinois IDDTPIFICATION OF OCCURRE!CE The electro:natic relief valve 203-3B failed to open during post-maintennnce testing of electree.2 tic relicf valves.

CONDITIONS PRIOR TO OCCURRC:CE The reactor was in tho start-up modo at 150 psig.

DESCRIPTION OF OCCURRD CE At 0030 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> on May 26, 1975, relief valvo 203-3B was actuated from the control room manually to verify operability. The pilot valvo for the relief valve indicated a temperature increase when actuated. However, the raain steam bypass valvo, which was bypacsing tho steam to the condenser, did not close when the relief valve was actuated. The r:aintenance foreman entered tho drywell and verified that the pilot valvo was indcod opening, but that the cain relief valve was remaining closed.

0304110010 750603 PDR ADOCK 05000237 S PDR [y []

Mr. James G. K pplir 2- Junt 3, 1975

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,Tha 3B valva was cgain tested g.t a rrector prazaura of approximatsly 300 prig.

TheIvalve again failed to show a decrease in bypass valve opening but did exhibit a temperature increase downstream of the pilot valve. At this time the valve was declared inoperable and the HPCI surveillance was started.

DESIGNATION OF APPAPS?? CAUSE (Component Failure)

The cause of the problem at this time is unknown since the reactor is operating with all required surveillances completed. Unit- 2 will operate up to 30 days in this condition and then shutdown for repair. This is allowed by Sect. 3.5.D.2 of the Technical Specifications. The cause will then be determined and a supplemental report submitted.

ANALYSIS OF OCCURPr!CE -

Prior to this failure, on May 20, 1975, electromatic relier valve 203.-3c failed to operate during post-maintenance surveillance at a rated reactor pressure (See report no. 50-237/75-30). As a result of this failure, a drywell entry was made upon subsequent shutdown, revealing that the operating am for the pilot valve was oat of adjustment. All valve operating arms were adjusted and the reactor was brought to criticality. Valve 3B had operated successfully on the first surveillance test and also after the pilot am adjustments were made. All valves had been ecmpletely overhauled, including pilot valves and main valves, during the Unit-2 refueling outage. A modification was also made to the main valve retainin6 dise locking uire. A castellated nut and cotter key were installed, per Dresser Valve recc=mendations, to prevent

the locking wire from loosening and obstructing operation of the valves, i

All required surveillances wora cuccessfully completed after the failure of the 33 valve. Since all other valves operated properly and the HPCI system curveillance test wa's successful,. reactor operation wac continued without undue risk to the hcalth and safety of the plant personnel and the public.

4 CORRECTIVE ACTION Corrective action will be determined when the reactor is shut doun within 1 30 days and the 203-33 valve is examined for the cause of failure. A j cupplc= ental follow-up report, will be suhnitted.

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's FAILURE LATA j A similar failure occurred on Unit-3 on January 16, 1974 as reported in letter j //57-74. At that time the failure uns attributed to a mnged disc retainer threads. The disc retainer, being cocked in the valve, prevented operation of the valve.

During the refueling outage on Unit-2, a modification to prevent this type of occurrence had been installed on all electromatic relief valves.

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, .Sr. Janea G.'K;p  ? Juna 3, 1975 l

The electromatic relief valves are 6" valves, catalogue no. 1525-VX, manufactured I by Dresser Industrial Valve.

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B B.lfephenson Superintendent BBS:JSK:c=p FileARC e

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