It appears that the prompt neutron flux has dropped, this may indicate that they have reduced the criticality of the uranium soup in japan... This could be very good news.

Now if they can get it cool and get more moderators in....

http://home.kyodo.co.jp/

22:02 Indonesia's new MPR to be inaugurated Friday -JAKARTA

Last update 07:30 JST Oct. 1 (UTC+9hrs)

07:08 Neutron monitor at Tokaimura plant shows zero radiation

07:04 Radioactivity around nuclear plant drops sharply -TOKYO

06:54 IMF chief hails BOJ's 'flexibility' in monetary policy -WASHINGTON

06:52 Nearby railways suspended from start due to nuke accident

06:48 IMF, World Bank urge financial reform, poverty easing -WASHINGTON

06:42 Radiation level plunges by 80 pc at 4 a.m. from midnight

06:31 Operation to destroy coolant-water pipes under study -TOKYO

06:27 Operation to destroy coolant-water pipes starts -TOKYO

06:09 Operation to destroy cooling-water pipes starts

06:02 No. of exposed victims to radiation up to 35

-- Helium (Heliumavid@yahoo.com), September 30, 1999

Answers

K.Stevens,

Is this possibly only the "temporary" halt you were referring to in the tread below?

-- (snowleopard6@webtv.net), September 30, 1999.

It appears that they have dropped the water cooling around the vessel. This will work for a while but if stuff heats up it could melt its way out. This is a good start, but they are not out of the woods yet.

http://dailynews.yahoo.com/h/nm/19990930/ts/nuclear_japan_25.html

Japan Says Chain Reaction At Plant Appears Over

MITO, Japan (Reuters) - A nuclear chain reaction at a uranium processing plant north of Tokyo appears to have been halted, although officials are still seeking final confirmation from radiation monitors at the plant.

-- Helium (Heliumavid@yahoo.com), September 30, 1999.

Can you imagine if this would have happened during a power failure at rollover?

-- a (a@a.a), September 30, 1999.

a--yes, I can imagine this could happen during rollover, power failure or not. I saw a tv piece that said, don't worry because we have the NRC! Ha ha ha ha.

-- Mara Wayne (MaraWAyne@aol.com), September 30, 1999.

Even after (and if) this is gotten under control, the entire building (at least) will remain a hazardous site. A high neutron flux converts some normally stable isotopes into radioactive isotopes.

Some mistakes, such as this one, are not learning opportunities for the persons who make them. That's why chickens never learn not to cross the road.

-- Tom Carey (tomcarey@mindspring.com), September 30, 1999.

The worker (a young lady) interviewed , said repeatedly, "they (the plant operators = gov.) kept telling us that it was all ok, even after the last time (last accident), they kept telling us it was all fixed"

Appears that Japan has had 7 plant accidents in the recent past, sounds toooooo familiar to me!

-- Michael (mikeymac@uswest.net), October 01, 1999.

Calm down. There is no reactor core, no meltdown possibility...it's a uranium fuel fabrication plant. Apparently a source of UF6 somehow was improperly mixed and lead to a critical concentration of U-235 fissile isotope. This created a prompt supercritical reaction, that naturally self-extinguished in probably less than a second (like the experiments I did in Grad School). Workers in the room probably got a lethal dose of prompt gammas and neutrons. Possibly a uranium fire, too (very pyrophoric as pure, not oxidized, form).

Don't jump to conclusions with uncertain facts

-- Bob, Ph.D. Nuclear Eng. (janebob99@aol.com), October 01, 1999.