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

["Joaquin Bustelo" <jbustelo@xxxxxxxxx>]

Joaquin: Divide the 1000 year event by 50, and you get that, on average, a
French nuclear power plant will face one of those "freak"
earthquakes every 20 years.
 
David: "Im dying here! I bet your wonderful 12 year old son can see whats
wrong with this math. I love it! Ha!
 
"Soseeing as its STILL one event in 1,000 years (no matter how many power
plants you have, or how many widgets or French bistros :). I couldnt find
much of French seismic activity, of which there is a lot of but not very
large. As the Japanese quake proved, and if you had read the paper instead
of being stopped by your inability to do averages (no, really, Im still
laughing about that) youd see that Japanese NPPs have stood up to a lot
worse. They all have settings designed to trip the unit off line (both the
reactor and the turbine-generator) before things start splitting open and
causing problems.

Joaquin: It's David whose love for nukes has made him unable to do the math.

The original paper said, "Nuclear facilities are designed so that
earthquakes and other external events will not jeopardize the safety of the
plant. In France for instance, nuclear plants are designed to withstand an
earthquake twice as strong as the 1000-year event calculated for each site."

Notice the last part of the second sentence: "the 1000-year event CALCULATED
FOR EACH SITE."

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.

So a 1000 year event represents a 0.1% probability. Add 50 of those together
(or multiply by 50, you remember, multiplication is just repetitive
addition) and you get a 5% probability that such an earthquake will strike
ONE (not all fifty) of those plants. 

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.

Joaquín


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