Posted by Morris Dovey on March 20, 2011, 4:56 pm
I think I must be missing something. I've been watching/reading the news
stories reporting the pronouncements of the Japanese government and TECO
(operator of the Fukushima reactors).
The news stories have been amazingly devoid of real information. It's
been very frustrating for me - so I decided to do a bit of amateur
research to see what numbers might be available, and to see if any real
conclusions might be reached on the basis of those numbers.
I found a few numbers that seem to expand on what's been reported in the
press - and they've led me to a different perspective than what the
press (reporting what the PM and TECO announce) seem to be promoting.
I've put the most solid of my few discoveries into a web page at
and, knowing that there are a few folks in the group who have actual
reactor experience, would like to invite corrections and comments on my
Posted by vaughn on March 20, 2011, 7:35 pm
My reactor experience is entirely with military pressurized water reactors
(PWR), which are somewhat different from any commercial reactor and even more
different than a boiling water reactor (BWR) like those in the recent news.
That said, many of the basics are the same. I have read that those plants are
virtually identical to American BWR plants of the same vintage, so you don't
need to do all of you research on Japanese sites.
In designing any power-producing reactor, engineers obsess about the theoretical
hottest spot in the reactor. Providing enough thermal safety margin for that
hopefully non-existent "spot" is what drives the thermal engineering of the
entire plant. It will be a spot within the fuel assembly that happens to have
the highest thermal flux coupled (for some reason) with the lowest coolant flow.
Everything else in the reactor will be cooler. The outside couple inches of that
6-inch thick pressure vessel are liable to be the coolest of all. Now that the
cooling flow to the reactor is gone, the temperature gradients will decrease,
but we still can't assume the same temperatures all through the plant. . .
Posted by Tom P on March 20, 2011, 8:50 pm
On 03/20/2011 08:35 PM, vaughn wrote:
Another consideration is that the tensile strength of steel drops well
below the melting point.
Posted by Gordon on March 20, 2011, 11:52 pm
And I understand that these reactors are GE BWR2 reactors.
Posted by daestrom on March 22, 2011, 10:33 pm
On 3/20/2011 19:52 PM, Gordon wrote:
Not 2's, one 3 and the rest 4's. The differences have to do with the
use of jet pumps and RCIC for isolated cooling instead of isolation