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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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