ML17252A200
| ML17252A200 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 05/27/1976 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler NRC/RGN-III |
| References | |
| BBS Ltr. /t412-76 50-249/1976-7 | |
| Download: ML17252A200 (3) | |
Text
".
Commonwec4t Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920 BBS Ltr. /t412-76 May 27, 1976 Mr. James G. Keppler, Regional Director Directorate of R~gulatory Operations -Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois.
60137 Enclosed please find Reportable Occurrence number 50-249/1976-7.
This. report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B.
BBS:smp Enclosure
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~. :B. Stephenson f"' Station'-£uperintendent Dresden Nuclear.Power Station cc:
Director of Inspection & Enforcement Director of Management Information & Program Control File/NRC JUM 5807
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EVENT DESCRIPTION (continued) and reactor power was reduced. to clear the alarms..
After tne* al*arms had. cleare.d, power was slowly increased until 0450 hours0.00521 days <br />0.125 hours <br />7.440476e-4 weeks <br />1.71225e-4 months <br />, when an apparent off-gas.explosion occurred.
Reactor power was further reduced to approximately 360 MWe.
Standby steam jet air ejector (SJAE)
"3Awas placed in service; However, further investigation indicated that the rupture diaphragm in both SJAE's had been damaged, and a unit shutdown was initiated and completed by 1038 hours0.012 days <br />0.288 hours <br />0.00172 weeks <br />3.94959e-4 months <br />.
Off-gas.
system explosions have occurred previously on both units 2 and 3.
'corrective action implemented was replacement of the failed diaphragms and the "3B" off-gas filter.
.(050-249/76-17£))
CAUSE DESCRIPTION _(continued)*
The explosion apparently failed both SJAE diaphragms at the same time.
It is assumed that *the pressure wave failed the rupture diaphragms in*
both the operating SJAE "3B'i andQthe standby SJAE "3A" due to leakage through the discharge valve.
- Although personnel on shift at the time reported hearing two expiosions, no evidence could be found to support this theory.
The "3B" off:....gas filter ir].: service at the time of the explosion. was damaged and subsequently '*~eplaced. Prior to the unit startup,* lDOth f:i,l_ters were tested. ancf 6fr-gas system valve lineups were verified to be correct.
An investig~tion of this ~nd other.. previous off-gas explosions has been initiated.
The investigation wil.l address the origin and prevention of off-gas syst.em explosiqns.
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