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Re: FW: Dateline NBC TMI story - A different evaluation
Will someone open a separate chat room for this and
spare me the constant dribble, thin-skinned reaction
and subsequent backtracking. Learn from it and move
forward.
--- "Careway, Harold A. (PS, NE)"
<Harold.Careway@gene.GE.com> wrote:
> Such failures of the vessel and containment are
> considered in the
> probabilistic risk assessment portion of the
> licensing documentation. This
> is to separate it from the design basis portion of
> the licensing
> documentation which is used to address specific
> regulatory rules. The PRA
> assess both equipment failure and human failure in
> the event progression.
> You are required in the probabilistic portion to
> evaluate the probability of
> a (1) core damage event, (2) vessel melt through,
> and (3) containment
> failure events and to determine what design
> applications could most
> significantly modify those probabilities, i.e., if a
> design change of
> $100,000 could reduce the probability of core melt a
> factor of ten, then you
> would do it; whereas a design change of $20,000,000
> for a reduction of 4%
> would not be done (4% is way below the precision of
> such calculations).
> Even so the regulators have the right to negotiate
> modifications based upon
> such studies (the NRC also does their own study as
> opposed to relying on
> just the utility licensing input).
>
> With respect to the potential for ground water
> contamination, it is
> typically not considered in the design of the
> reactor building but is
> considered in the design of the radwaste building.
> This is due to the fact
> that designing the reactor building for seismic and
> leakage constraints most
> often results in a containment impervious to such
> melt through leakage to
> the ground water. When you think of a reactor
> building, don't think of the
> kind of building you work in, consider 5 meter thick
> concrete basemats,
> reinforcing steel woven so thick you can barely
> stick your finger between
> the bars, one meter concrete floors, steel lined
> containments so tight that
> the allowable leakage area is about that of a 0.5mm
> pencil lead area,
> passive flooding systems, and basaltic concrete
> designed to withstand melted
> steel/corium. These are truly tough buildings, most
> of which are
> underground.
>
> -----Original Message-----
> From: Jacobus, John (OD/ORS)
> [mailto:jacobusj@ors.od.nih.gov]
> Sent: Friday, August 17, 2001 5:52 AM
> To: Franz Schoenhofer; Ted Rockwell; Michael Stabin;
> radsafe@list.vanderbilt.edu
> Subject: RE: Dateline NBC TMI story - A different
> evaluation
>
>
> Franz and Ted,
> .....
>
> I do not know a lot of nuclear engineers, so again I
> ask if the idea of a
> core meltdown that lead to a failure of the
> containment vessel and
> containment building was considered follow a loss of
> coolant, AND failure of
> the emergency core cooling system. (Gee, that
> sounds like what happened at
> TMI when the control room turned off the emergency
> fuel pumps.)
>
> .....
> -- John
>
> John Jacobus, MS
> Certified Health Physicist
> 3050 Traymore Lane
> Bowie, MD 20715-2024
>
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