ML20084D494

Ro:On 730419,secondary Containment Integrity Not in Effect for Approx 6 H.Caused by Turbine Bypass Valve & Two High Pressure Turbine Steam Lines Being Open to Turbine Bldg,Due to Maint Insp.Blind Flange Installed & Containment Restored

ML20084D494
Person / Time
Site:	Dresden
Issue date:	04/27/1973
From:	Worden W COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
2830, 337-73, NUDOCS 8304120057
Download: ML20084D494 (2)

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s50-249 Commonwealth Edison Company ONE F1RST NATIONAL PLAZA

• C H I C A G O. ILLaNOIS Address RepI, to, POST OFFICE SOX 767

• C H I C A O O, ILLINOl5 60690 h Dresden Nuclear Power Station s %- . ,,

R. R. #1 .8 f'[.f $$ I.,I' f 'T Morris, Illinois 60450 .

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WPW Ltr. #337-73 April 27, 1973 APR30 ;073 .

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Mr. A. Giambusso < [ ./4 Deputy Director for Reactor Projects . J . > i ~ Q.h,. '

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Directorate of Licensing U. S. Atomic Energy Commission Washington, D.C. 20545

SUBJECT:

LICENSE DPR-19 AtiD DPR-25, DRESDEM UUCLEAR POUER STATION, UNITS

~#2 AND 3, SECTION 6.6.3.3 CF Ti!E T2CHNICAL SPECIFICATI0I:S.

Dear Mr. Giambusso:

This is to report a condition relating to the station in which on April 19, 1973, secondary containment integrity was not in effect for a period of approximately six hours, contrary to Technical Specifications Section 3.7.C.

PROBLE!! A!!D IIT/ESTICATICM At approximately 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on April 19,1973, unit 3 main steam isolation valve OGIV) 3-203-2B was disassembled for an inspection of the valve internals during a maintenance outage. Since the unit 3 turbine stop valves were also disassembled for inspection, opening valve 3-203-2B established'a direct flow path from the turbine ouilding into the turbine steam chest through main steam line 3-3001B-24" into the cain steam line tunnel, which is part of unit 2/3 secondary containment.

The investigation revealed a turbine bypass valve and two high -

pressure turbine steam lines were open to the turbine building. The bypass valve flange was replaced at approximately 1730. Since the turbine steam inlet lines could not be reinstalled rapidly, a blind flange was installed on MSIV 3-203-2B.

Secondary containment is required at all times that primary contain-l ment is required as well as during refueling. During the short period of time secondary containment was broken, unit #3 reactor was in the refuel mode with local power range monitor (LPRM) replacement and fuel moves in progress and unit #2 was operating at near rated power.

4 63 .,e pry 8304120057 730427 PDR ADOCK 05000237 S PDR 2839

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The loss of secondary containment for this short period of time did not result in a ground icvel release since the air flow was into the secondary containment from the turbine building. Had an event occurred which resulted in release of radioactivity to the secondary containment and had the air flow direction been reversed, a release path would have existed from the secondary containment to the turbine building.

CORRECTIVE ACTION A blind flange was installed on MSIV 3-203-2B at 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> and secondary containment was restored. A change will be made in the " Request for Equipment Out of Service" form to include a " Secondary Containment Integrity Effected" check space. This change should be completed by June 1, 1973.

Sincerely, (0, Ukw W. P. Worden Superintendent WFW:RC:jw cc: UPW Ltr. File i

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