Posted by | March 12, 2011 13:33 | Filed under: Planet Top Stories

An explosion at the Fukushima Daiici nuclear plant in Okuma Japan seems to have caused a meltdown.

A meltdown occurs when the control rods fail to contain the neutron emission and the heat levels inside the reactor thus rise to a point that the fuel itself melts, generally temperatures in excess of 1,000 degrees Fahrenheit, causing uncontrolled radiation-generating reactions and making approaching the reactor incredibly hazardous. A meltdown does not necessarily mean a nuclear disaster. As long as the reactor core, which is specifically designed to contain high levels of heat, pressure and radiation, remains intact, the melted fuel can be dealt with. If the core breaches but the containment facility built around the core remains intact, the melted fuel can still be dealt with — typically entombed within specialized concrete — but the cost and difficulty of such containment increases exponentially.

The big issue now is whether the floor of the containment vessel is cracked. Statfor explains the consequences.

Radiation exposure for the average individual is 620 millirems per year, split about evenly between manmade and natural sources. The firefighters who served at the Chernobyl plant were exposed to between 80,000 and 1.6 million millirems. The Nuclear Regulatory Commission estimates that exposure to 375,000 to 500,000 millirems would be sufficient to cause death within three months for half of those exposed. A 30-kilometer-radius (19 miles) no-go zone remains at Chernobyl to this day. Japan’s troubled reactor site is about 300 kilometers from Tokyo.

The latest report from the damaged power plant indicated that exposure rates outside the plant were at about 620 millirems per hour, though it is not clear whether that report came before or after the reactor’s containment structure exploded.

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Copyright 2011 Liberaland
By: Alan

Alan Colmes is the publisher of Liberaland.