ML20058K775

Ro:On 740520 Hydrogen Detonation Occurred Resulting in Blowing Out Both Air Ejector Discharge Line Rupture Discs & Releasing Off Gas from Reactor Bldg Vent.Cause Under Investigation

ML20058K775
Person / Time
Site:	Monticello
Issue date:	05/20/1974
From:	Larson C NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 9102140381
Download: ML20058K775 (1)

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-Manticello, Minns ata 55362 -

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'My 20,1974 . <?.

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'Mr. J. G. Kappler, Regional Director ,; i Directorate of Regulatary. Operations Region III ' -

799 P.cosevelt Pmad Glen Ellyn, Illirmi* 61073

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Dear Mr. Keppler:

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-N N GENERATINt3 PIMF ., l

-Ibckst'No. 50-263 License No. 5 1-22 l

--During startup an May 20, 1974, while operating at 575 psig reactor pressure and conducting cn-line resting of ths : :xiified off gas holdun system, a hydrceen detonation occurred resulting in b1c.iing out both air ejector discharge line i rupture discs and releasing off gas irca the reactor building vent. The mir"

- release rate was 6200 uci/sec for five minutes, then decreasing to less th: In

-100 uci/sec after 21/2. hours. 'At.no time was the technical specificaticn relcas l Limit of 210,000 uci/sec ow.-wW <

h cause-of the lydrogen detonation is under investigatien.

"Yours very t ., . i

C. E. .- -

Plant 15anager -

GI/nmut -

cc: .J F'O'Imary, Directorate of Licensing -

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-.G Charnoff i

" Minnesota Pollution Control Agency ,

, .Atta: E N Pryrdna l

'- . Pile Copies sent by teleccoier to Keenler and O'Icary e

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'9102140381 740520 63 ,

CF ADOCK 0500 ,

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