ML19295B991
| ML19295B991 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 02/10/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8010150687 | |
| Download: ML19295B991 (1) | |
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Docket No. 50-10 Docket No. 50-237 FEB 10.8 Docket No. 50-249 Docket No. 50-254 Docket No. 50-265 l
Consonvealth Edison Company ATTN Mr. Byron Lee, Jr.
Vice Praxident P.O. Box 767 Chicago, IL 60690 Centlement Enclosed is IE Bulletin No. 73-C3 which requires action by you with regard to your power reactor facilitian with an operating licenso.
Should you have questions regarding this Bulletin or the actions required of you, piense contact this office.
Sincerely.
O@
James G. Keppler Director
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Enclosures 1.
List of IE Bulletins Issued in 1978 cc w/encis:
Mr. B. B. Stephenson, Station l
Superintendent i
Mr. U. Kalivianakis, Station Superintendent Central Piles Ecproduction Unit NRC 20b PDR Local PDR NSIC tic
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Anthony Roiunan. Esq., Attorney l
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February 10, 1978 IE Bulletin No. 78-03 POTENTIAL EXPLOSIVE GAS MIXTURE ACCUMULATIONS ASSOCIATED WITH BWR OFFGAS SYSTEM OPERATIONS Description of Circumstances:
On December 13, 1977, two hydrogen explosions occurred at the Millstone Nucletr Power Station Unit No. 1, a boiling water reactor (BWR).
The first explosion occurred at 9:30 a.m. and was mostly confined to the offgas systen. Damage was relatively minor, including the breaking of glass faces on offgas system flow differential presure gages, the blowout of a rupture disk and the evacuation of loop seals between the offgas system drain lines and stack base sump.
The second explosion occurred at 1:00 p.m. outside the offgas system in the two-level room at the base of the plant stack. This expl)sion blev the stack base space door into a warehouse about 200 feet away, breached the reinforced concrete ceiling between the stack chimney and the stack base space, extensively damaged the ceiling beams, dislodged the 2-ton concrete plugs in the floor above the of fgas system particulate filters, damaged the stack radiatica monitor isokinetic probe supports, and produced cracks in the stack. These cracks were vertical, with a maximum separation at the surface of 1/16 inch; however, the overall structural capability of the stack was not impaired.
One man was injured by the blast, receiving a concussion, skin abrasions, and contamination. He was hospitalized because of the concussion and was released four days after the event.
The licensee's review of the event concluded that the action taken to restore offgas syste= drain line loop seals in the stack base space had not been successful. Without these seals, gases from the offgas system accumulated in.he space, resulting in an explosive mixture which was probably ign h rk from the level cwitch in the ation of the stack base spe.ce and onitor explosive gas concentrations DUPLICATE DOCUMENT luded to be contributing factors.
Entire document previously entered into systc= under:
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