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From: owner-extropians@extropy.org
Date: Sun Jan 07 2001 - 23:57:12 MST

2001 22:09:57 PST
Date: Sat, 6 Jan 2001 22:09:57 -0800 (PST)
From: John Marlow <johnrobertmarlow@yahoo.com>
Subject: Re: Nuke Weapon Mishaps--was Bill Joy on the CBS evening news
To: extropians@extropy.org
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Herewith, a report of an accidental NUCLEAR
criticality and consequent radiation release. Note
that Japan is non-Communist. Note also the level of
blinding stupidity. As Edward Teller once remarked,
Nothing is foolproof. Fools are so ingenious...

john marlow


Japan's Nuclear Criticality Accident

Steven Dolley Research Director Nuclear Control Institute

October 4, 1999

When and where did the accident take place?

An inadvertent nuclear chain reaction, or so-called "criticality accident," began at 10:35 AM local time on Thursday, September 30 at the JCO Co. Ltd. Conversion Test Building at Tokai-mura, Japan, about 75 miles northeast of Tokyo. The chain reaction, which gave off intense heat and radiation, could not be stopped until 18 hours later.

The accident began when workers were converting enriched uranium into oxide powder for use in preparing fuel for the Joyo experimental fast breeder reactor. This reactor is part of Japan's plutonium-production program. The uranium was enriched to 18.8% U-235, far higher than the 3 to 5% enriched uranium used as fuel in Japan's conventional nuclear power reactors. Breeder fuel, whether enriched uranium or plutonium, is far more susceptible to criticality accidents than power-reactor fuel.

What happened?

It appears that workers deliberately circumvented safety measures to save time. A solution of uranyl nitrate was transferred into a large-volume precipitation tank, rather than the smaller, cylindrical container required by regulations. According to JCO Inc. official Yutaka Tatsuta, one of the injured workers reported that some 16 kilograms of uranium solution had been poured into the precipitation tank, nearly eight times more than its criticality safety limit of 2.4 kilograms.

Workers reported seeing a blue flash and then started to feel ill. According to one report, "the area was wrapped in a haze of blue smoke." Workers told plant staff that "they saw a blue flame rising from the fuel." Kenji Sumida, a member of Japanese government's Nuclear Safety Commission, concluded, "I know this is difficult to believe, but I think that we have no choice but to recognize this accident as having been critical." The criticality continued for about 18 hours until the water that was moderating the flow of neutrons and allowing the chain reaction to continue was drained and the tank was flooded with boron, a neutron absorber.

How much radiation was released?

At one point, radiation levels near the plant were 15,000 times above normal background. A total of at least 49 people were contaminated with radiation, including 39 JCO staff, seven residents, and three firefighters who transported the injured workers. Two of the workers received such high doses of radiation that they are not expected to survive.


At 03:00 PM 1/5/2001 -0600, you wrote: On Fri, 5 Jan 2001 Eugene.Leitl@lrz.uni-muenchen.de wrote:

> Fissibles are quite easily controlled. Much more difficult with a virus > design kit, and quite impossible with nanotechnology, which provides and > propagates means for its own production. As soon as Pandora's box is open, > there's no going back.

I quite agree that nuclear weapons are an easier problem than biological or nanotech weapons. The orginal poster said that if "the consequences of failure" of nuclear weapons were the same as nanotech, we would all be dead. Not so, it is the nature of the technology, not the possible consequences, that determine the ease of control. I believe we are in violent agreement.


===== The strength to change what I can, the inability to accept what I can't, and the incapacity the tell the difference. ---Calvin

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