The risk to workers might be greater than previously thought because melted fuel in the No. 1 reactor building may be causing isolated, uncontrolled nuclear chain reactions, Denis Flory, nuclear safety director for the International Atomic Energy Agency, said at a press conference in Vienna.
On March 23, Dr. Ferenc Dalnoki-Veress, a Research Scientist at the Monterey Institute of International Studies saw a report by Kyodo news agency that caught his eye. It reported that Tokyo Electric Power Company (TEPCO) had observed a neutron beam about 1.5 km away from the plant. Bursts of neutrons in large quantities can only come from fission so Dalnoki-Veress, a physicist, was faced with an alarming possibility: had portions of one of Fukushima’s reactors gone critical?
To nuclear workers, there are few events more fearful than a criticality accident. In such a scenario, the fissile material in a reactor core–be it enriched uranium or plutonium–undergoes a spontaneous chain reaction, releasing a flash of aurora-blue light and a surge of neutron radiation; the gamma rays, neutrons and radioactive fission products emitted during criticality are highly dangerous to humans. Criticality occurs so rapidly–within a few fractions of a second–and so unpredictably that it can suddenly kill workers without warning. There have been 60 criticality incidents worldwide since 1945. The most recent occurred in Japan in 1999, at an experimental reactor in Tokai, when a beam of neutrons killed two workers, hospitalized dozens of emergency workers and nearby residents, and forced hundreds of thousands to remain indoors for 24 hours.
UPDATED: The IAEA has said that the Fukushima nuclear power plant may have achieved re-criticality. “There is no final assessment,” IAEA nuclear safety director Denis Flory said at a press conference on Wednesday, according to Bloomberg News. “This may happen locally and possibly increase the releases.”
Read on below the fold to see what purports to be a photo of the “blue flash”.
It’s an animated gif that is too annoying to post on the main page.
The source is a Japanese site, that I can’t read – so anyone that can help me track the origin and veracity of this
image, please weigh in.
Where’s the nomination form for the “Worst gif Of The Month” awards?
I warned you.