From: ems@michael.apple.com (E. Michael Smith)
Newsgroups: sci.energy
Subject: Re: Nuke Stupidity Rebuttal
Date: 26 Sep 92 08:34:14 GMT
Organization: Apple Computer Inc, Cupertino, CA

In article <1992Sep23.195247.1075@nuchat.sccsi.com> kevin@nuchat.sccsi.com (Kevin Brown) writes:
>In article <53806@dime.cs.umass.edu> yodaiken@chelm.cs.umass.edu (victor yodaiken) writes:

>So: how many worst-case failures, of the kind you refer to, have happened
>in the history of the world to reactors of the kind used in the U.S. and
>Canada?  I dare say none have.
>
>How many average-case failures have occurred?  I dare say more than zero.
>
>Since more average-case failures have occurred than worst-case failures,
>it seems ludicrous to suggest that a worst-case analysis is a better
>means of comparison than an average-case analysis.
>
>And so I reiterate my question: what is this obsession you have with
>worst-case failure modes?

By this logic, since I've never died and I've lived a relatively 
long time already, and all the bad things I've ever experienced
were far less than 'worse case' (i.e. dying) I shouldn't worry
about the possibility that I might someday die, since it has never
happened in my history and must therefore be so remote as to be a
ludicrous thing to even consider...

Ditto the case for condoms.  Since I've got a very low chance of getting
AIDS (or getting someone pregnant) why worry about it?  Ditch that 
condom today!  The 'average-case' failure of lack of a condom is that
you have a great time.  Once in a while you get some treatable disease.
Only very rairly would you get AIDS or have a pregnancy.  So what is
this obsession with the worst-case failure modes?  Heck, I've known 
couples who tried for YEARS to get pregnant.  Who needs condoms!

The fact is that we havn't had enough reactor-years of experience to 
have had the very low probability modes of failure manifest.  This is
a testimonial to the designs we've used, but does not PROVE the the 
failures WILL NOT happen!  A one in ten thousand reactor-year failure 
ought not to have happened in the first few years of reactor use!

>>Low probability/high consequence
>>events are not necessarily equivalent in riskiness to high probability
>>low consequence events. 
>
>By what measure is *this* true?  I was under the impression that the
>very *definition* of statistical risk was probability times cost.

See my other posting on the evaluation of risk to sort this one out.
The two of you are using 'risk' differently.  One includes the value
placed on the outcome, the other just notes the cost in abstract terms
but does not value the quality of the risk.

>In terms of demonstrating objective correctness, correspondence to human
>intuition of risk is irrelevent.  All that matters is that the predictions
>match real-world observation.

This dodges the issue of the value put on a particular magnitude of risk.
'Quantity has a quality all its own' holds here...

>In terms of convincing people who are unable or unwilling to put aside
>their intuition in favor of an objective model, I agree that one must
>show the correspondence between the equation and human intuition.

This again dodges the issue of valuation of a risk.  Value is, and
must always remain, a human intuitive process.  I've watched BOTH 
my parents die from cancer.  I would value a quick death from some
other process much more highly than a slow wasting death from cancer.
This VALUATION of the risk of cancer death will change how I value
the risk of extra cancers in the population ...  even if the abstract
model predicts equal deaths from cancer and from accident for two
competing scenarios, I'd VALUE them differently.  This is NOT irrational,
the is respecting the human condition.  This doesn't deny the accuracy
of the analytical model.  It does challenge the conclusions drawn from it.

-- 

E. Michael Smith  ems@apple.COM

'Whatever you can do, or dream you can, begin it.  Boldness has
 genius, power and magic in it.'  -  Goethe

I am not responsible nor is anyone else.  Everything is disclaimed.