Re: [Marxism] Paper on Japanese nuclear reactors and earth quakes

[Les Schaffer <schaffer@xxxxxxxxxxxxx>]

Joaquin Bustelo wrote:
> It is not ONE 1000-year event, it is FIFTY-SOMETHING 1,000-year events.
> That's the point. Risks are ADDITIVE, you know, one plus one equals two.
>   

JB is more right here than David. The article David pointed to did
*seem* to say that each site would have its own 1 in a 1000 year event.

*if* the events were probabilistically independent, then adding the #s
is the way to go. its probably also an overestimate, since fault line
activity as far as i know (gotta ask my geophysics buddy) is not totally
independent.  and the siting of power plants is such that you are
sampling these events, but not always at full strength. some plants will
be more isolated from events than others.  etc etc.

so its reasonable -- absent further info -- to pick some # between 1 in
1000 and 50 in a 1000.
> David adds he couldn't find much information on seismic activity in France.
> Precisely. The scientific record of these events doesn't stretch back many
> decades, does it? These sorts of odds are suitable for insurance companies,
> gambling, not for serious engineering and design work.

the article i forwarded yesterday talks about using "geo-morphological
data" to peer further back than the seismic record. even the operators
of the Japanese plant admitted last week that this new type of data
should be considered -- and in fact is now required to be examined by
Japan's own rules of order.

i think the operators of the Kashiwazaki-Kariwa plant have a genuine
headache on their hands. they know that the seismologists who rumbled
about fault lines were not off their rocker. PLUS, they had a genuine
strong event with acceleration profiles that were *double* the design
spec. this is not a good thing. Much was made of how the reactors were
quickly shut down when the seismic activity was detected. i say
mazel-tov. but what about all the structures designed for large
amplitude vibrations? do you go in and check ALL the welds and supports?
do you go look at your previous "factor of safety" and play "roll the
dice"? or do you just suppose that because there was no serious failure
during the quake, all structures are intact?

anyone for a little poker?

still, i like David talking from the control room. the more one can
dispel irrational fears the better. and yes its good to be reminded the
CO2 gun is out there too.

Les


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