ML20029B673

Nonproprietary Estimated Blast Effect from Ft St Vrain Well 11 Analysis Methods Summary.

ML20029B673
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/05/1991
From:	Morris B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19310D318	List: ML20029B667 ML20029B671 ML20029B673
References
NUDOCS 9103140066
Download: ML20029B673 (2)

Text

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i Westinghouse Proprietary Class 3 I

l Estimated Blast Effects from Fort St. Vrain Well #11 l

Analysis Methods Summary I

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E Estimated _ Blast Effects from Ft. St. Vrain Well fil Analy$is-Hethods Summary

This report sumarizes the scoping analysis of the potential effects from the release of natural gas from the number 11 well. 1he analysis includes the following scenarios; o 1 x 105 cy.bic feet per day, no wind o 1 x 105 cubic feet per day, 5 mph wind o 1 x 105 cubic feet per day, 1 mph wind, in addition,.the confined explosion of a small metering shed was modeled.

Finally, since it was assumed that the release gas was 100% methane, an evaluation was made of the potential effects that might be associated with the 10% ethane in the stream, due to its higher density and lower-

-flammability. The results of this evaluation indicated that assumption of a neutrally buoyant,100% methane release encompassed all the consequences of the ethane.

For the antilysis of the unconfined vapor explosion the following assumptions apply:

o the gas is assumed to be 100% methane, o the gas is assumed to be neutrally buoyant, >

o the atmospheric stability is a Pasquill F" Class, o the terrain is level and the wind is blowing toward the reactor building, wind velocities of 5 and 1 MPH, o The wellhead is 1150 feet from the Reactor Building, and the

metering station is 950 feet from the Reactor Building.

The evaluation of the unt.onfined vapor explosion provided an estimated maximum " worst case" over pressure of 0.6 psig at the reactor building for the analysis which assumed no gas dispersion, assuming a release rate of 1 million standard cubic feet per day for a duration of one hour. Also, over. pressures of 0.3 and 0.1 psig were estimated for scenarios vhich accounted for. the downwind dispersion of this release, using 1 MPH and 5 MPH windspeed, respectively.

The results for the confined explosion indicated over-pressures of less than 0.03 psig at the reactor building, assuming that the shed will fail at internal pressures below 5 psig. This is consistent with the assumed building construction type, i.e. frameless steel.

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