ML17252A473
| ML17252A473 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/17/1974 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler US Atomic Energy Commission (AEC) |
| References | |
| Download: ML17252A473 (2) | |
Text
OEC Commonwe~Edison One First Nation~za, Chicago, Illinois *.
Address Reply to: Post Office Box 767'
- Chicago, Illinois 60690 BBS Ltr#900-74 Dresden Nuclear Power Station R.R. #1 Morris, Illinois December 17, 1974 Mr. James G. Keppler, Regional Director Directorate of Regulatory of Operations-Region III
- u. s. Atomic Energy Commission.
799 Roosevelt Road Glen Ellyn, Illinois 60131'
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s~T: REPORT OF UNUSUAL EVENT PER*SECTION 6.6.c *oF THE TECHNICAL SPECIFICATIONS DRESDEN UNIT/~*o. AEC. oocm. ~0~249 :
References:
- 1) Regulatory Guide 1 *. 16 Rev. 1 *:Appendix A
- 2) Dresden Station Drawing M-358 *
- 3) Dresden ElectricaiPrij).t_t2E343t Report Date:
December* 17; 1974 Occurrence Date: November*27, 1974 :
Facility: Dresden Nuclear Power Statl.on, Unit*_:~3, Morris, Illinois IDENTIFICATION OF OCCURRENCE.
Core Spray valv~ M0-3-14o2-24A failed to open during valve operability check.
CONDITIONS PRIOR TO OCCURRENCE Prior to the failure of core spray vaiveM0~~1402-24A to open the unit
~s in the start-up mode and recovering from a.s.cram which occurred earlier that day. *At the time of the failure~ sfut..:U:p checks were in progress.
DESCRIPl'ION OF OCCURRENCE On November 27, 1974 at -about 1800 ho:UZ,s-a valve operability check was being performed prior to unit start-up. *Normally open valve M0-3-1402-24A was cycled to the closed position. Upon closing, valve position indications were lost. Attempts to re-open the valve electrically were unsuccessful.
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Mr. James G. Keppler *
- -l-/ *.,,..:..-x ~ember 17, 1974 DESIGNATION OF APPARENT CAUSE OF OCCURRENCE Upcn=iI:lY.estigation it was determined that the scram on November 27, 1974 was due to a water hammer in the core spray system which inadvertantly actuated the Main Steam Line Flow switches. During the water hammer the limit switches for the 3-1402-24A valves were damaged.
On inspection of the limit switches it was found that the contact base plates were cracked which allowed to contacts to become misaligned, and preventing proper valve operation *
.ANALYSIS OF OCCURRENCE During the failure of the Core Spray valve 3-1402-24A the safety of the.
plant and public was not in jeopardy. The 3-1402-24A valve was-manually opened to maintain core spray system operability until repairs were completed.
In ~ddition, all other safety systems were operational at the time of the failure.
CORRECTIVE ACTION
- The immediate corrective action taken was to manually open the 3-1402-24A valve until repair~ were completed. A modification has been initiated to relocate the Main Steam Line Flow switches to an area were they would not be affected by core spray operation. In addition, all the limit
- switches associated with core spray 'm¢:gr-operated valves were inspected and* no additional anomalies were noted.
FAILURE DATA The last reported failure of a core spray 24 valve occurred on February 5, 1971,.
in association with the 2_;1402-24B on Unit two.
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s~;ff tjf.~on SuPerintendent