Text 15712, 84 rader
Skriven 2011-03-23 10:57:50 av Scott Little (3:712/848)
  Kommentar till text 15632 av Lee Lofaso (1:323/120.0)
Ärende: Japan
=============
 [ On 2011-03-21 at 15:13:32, Lee Lofaso wrote to Scott Little ]

 LL> How much time is needed?  Do you know?

No.

However, I know it's not a case of time, but the amount of heat generated. 
Even used fuel that's been removed from the reactor still continues to generate
heat, which is why they're kept in cooling tanks for decades.  It's not a case
of cooling it down, then it's fine like quenching a piece of red hot steel,
it's an ongoing process.

That doesn't mean if it loses cooling at any time it'll explode, though
(otherwise what's the point shutting a reactor down at all?).  Without cooling
heat will build up, so how long they get to restore cooling depends on how much
decay heat is left in the fuel.  And whether or not they're trying to salvage a
working reactor vs averting an environmental disaster ;)

 LL> And what about structural damage?  Water is heavy.  And when a massive
 LL> wall of water slams into a building, especially at a high rate of
 LL> speed, the damage can be catastrophic.

Depends on whether the pressure vessel is above or below ground I suppose.  If
it's set into a concrete floor, then water and debris would probably wash over
it.  Of course all the supporting infrastructure above will get washed away,
which is Bad.

 LL> How many dead Japanese are there, so far?  18,000+ that we know about.
 LL> How many future dead Japanese will there be?  Probably a lot more than
 LL> 18,000+.  Many due to radiation poisoning.

How many is "many"?

It's a natural disaster, they kill people and break things.  And the reactor
didn't cause it.  The fact that "many" might die because of a damaged reactor
should not be considered inherently worse than the same "many" (or more) that
did die because the office building they were in collapsed.

 LL> entire site, mortar and all.  The reactors in Japan are still
 LL> standing. For the most part.  But there is still a lot of radiation
 LL> that has been leaked, and continues to leak.  Radiation has been found
 LL> in crops.

How much radiation, what kind, which crops and which farms?

It doesn't take much to get the media's panties in a twist.  At least, as long
as it's related to nuclear reactors and not a natural phenomenon:

http://en.wikipedia.org/wiki/Brazil_nut
http://www.orau.org/PTP/collection/consumer%20products/brazilnuts.htm [23]

Brazil nuts also contain small amounts of radioactive radium. Although the
amount of radium is very small, about 1-7 pCi/g (40-260 Bq/kg), and most of it
is not retained by the body, this is 1,000 times higher than in other foods.
According to Oak Ridge Associated Universities, this is not because of elevated
levels of radium in the soil, but due to "the very extensive root system of the
tree." [23]


         -= A THOUSAND TIMES HIGHER!!! THE END IS NIGH!!!!!1 =-


 LL> Three Mile Island was considered as being a "modern commercial power
 LL> reactor" - until disaster struck.

Anyone that thinks TMI was a disaster (other than financial) isn't really worth
talking to.

Nobody died, but it happened at a nookoolar reactor, IT'S THE END OF THE
WORLD!!!

Emotional drivel.  Industrial accidents happen all the time outside the nuclear
industry, often someone dies and lots of property is destroyed, TMI should not
be considered any differently.

 LL> All of today's reactors in the USA (and elsewhere) are considered as
 LL> being "modern commercial power reactors"

Maybe at the time, but not since TMI/Chernobyl.  Today, a reactor isn't
considered modern unless it's passively safe.


--- Cats remind us that not everything in Nature has purpose.
 * Origin: sysgod@sysgod.org (3:712/848)