Re: Luck and analysis

["HP Dean" <RadConDean@comcast.net>]

I will agree with Brian on the fact that conservative engineering and not

luck, played the biggest role.  Maybe, except for the poor luck of the draw

involving some "reactor experts" forced on the NRC by the Carter

administration.  These experts created the "hydrogen explosion" scenario.

Yes, there was also some luck involved - in the fact that control room

operator intervention didn't result in a worse accident.  Is it "luck" that

caused the safety systems responded as designed.  So what, if the melt would

have penetrated the vessel?  It still would have loss its favorable geometry

and resultant heat from fission, and would be immersed in water on the

reactor vessel pad.  I had read the tomes on the TMI accident produce by the

NRC and the TMI commission, but cannot remember whether decay heat or heat

from fission cause the majority of the core structure damage.



Dean Chaney



----- Original Message ----- 

From: "Brian Rees" <brees@LANL.GOV>

To: <radsafe@list.vanderbilt.edu>

Sent: Tuesday, March 09, 2004 9:53 AM

Subject: Luck and analysis





> Now hold on here a minute.  Some people are referring to a heat transfer

> factor that was not analyzed at TMI, one that was greater than expected,

> causing a conservative result.  That's what conservative calculations buy

> you.  When we do calculations (at least when I do them) in health physics,

> a factor may not be fully analyzed, we know from our professional

> experience and training that its effect will be more conservative than the

> assumption we make, so we move on.  We don't analyze every stinkin' factor

> to the nth degree, it's not warranted.   So when something bad happens

it's

> not as bad as we "predicted", although we're already ignoring the

> conservatism we used.

>

> Now I don't want to say that TMI was without some luck, there were still

> things that should not have happened, but it was not just luck that kept

> things from getting dangerously ugly.

>

> (Obviously) my own personal opinion.

>

> Brian Rees

>

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