Partial Meltdowns in 3 of 6 reactors Believed now

http://www.cnn.com/2011/WORLD/asiapcf/03/29/japan.nuclear.reactors/ 
Japanese officials and international experts have said they believe there's been a partial meltdown at three of the plants six reactors.
"The high radiation levels on site seem to support that idea. There is no visual proof yet, but it's increasingly likely there was partial fuel melting," said Gary Was, a nuclear engineering expert at the University of Michigan.
And water runoff isn't the only potential threat complicating efforts to contain the crisis.
Plant owner Tokyo Electric Power Company announced late Monday that tests detected low levels of plutonium in soil near the plant. The radioactive element is a reactor byproduct and part of the fuel mix in the No. 3 reactor.
The plutonium likely came from the plant, Edano said Tuesday.
"If we detect higher levels of plutonium, we have to take additional measures, so our intention for now is to carry on with the monitoring on-site," he said. end quote.

So, now both Japanese officials and International representatives believe that there are at least 3 partial meltdowns at Fukushima Nuclear power plant. So, the likely partial meltdowns are Reactors 1, 2 and 3.
Reactor 3 is the Uranium and Plutonium power reactor which uses Mox fuel:

Mixed oxide fuel, commonly referred to as MOX fuel, is nuclear fuel that contains more than one oxide of fissile material. MOX fuel contains plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium (LEU) fuel used in the light water reactors that predominate nuclear power generation. For example, a mixture of 7% plutonium and 93% uranium reacts similarly, although not identically, to LEU fuel. quote from Wikipedia under the heading "MOX Fuel".

The term depleted Uranium is often used in conjunction with anti-tank weapons that with this depleted uranium tend to melt tanks when they hit them. (Some of the tanks hit in Libya are likely melted from this type of weapon). It was used on tanks also in Iraq and before that in Desert Storm. But plutonium is used more with  Thermonuclear weapons. So when nuclear weapons are reprocessed they are put into MOX fuel sometimes as one of the components. However, plutonium tends to be 2 million times more toxic to all life than uranium.

next quote from top of page article:
Plant owner Tokyo Electric Power Company announced late Monday that tests detected low levels of plutonium in soil near the plant. The radioactive element is a reactor byproduct and part of the fuel mix in the No. 3 reactor.
The plutonium likely came from the plant, Edano said Tuesday.
"If we detect higher levels of plutonium, we have to take additional measures, so our intention for now is to carry on with the monitoring on-site," he said.
The power company said it would increase monitoring in the area, but noted that the amount detected was equivalent to the amounts that fell on Japan following above-ground nuclear weapons tests by other countries in past decades, and posed no health risk to humans.
The element can be a serious health hazard if inhaled or ingested, but external exposure poses little health risk, according to the U.S. Environmental Protection Agency. end quote.

So, paraphrased, "The element(plutonium) can be a serious health hazard if inhaled or ingested---"

So, for example if you breathe in one particle of plutonium or eat one particle of plutonium or more it likely eventually will be fatal (If) any one or more particles stay in your body in your lungs or intestines or if the radiation it taken into your thyroids,Aureola or sexual organs (in the case of radioactive thyroid). However, plutonium anywhere inside your body if it stays there (even one particle) will likely be fatal within 20 to 30 years and sooner if there is more than one particle present.

next quote same top article:
he 1,000 millisievert per hour reading was more than 330 times the dose an average person in a developed country receives per year and can result in vomiting and up to a 30 percent higher risk of cancer, according to the International Atomic Energy Agency. The level is also four times the top dose Japan's Health Ministry has set for emergency workers struggling to control further emission of radioactive material from the damaged plant. end quote:


1,000 millisieverts is considered a potentially fatal dose by U.S. Nuclear officials. 50 millisieverts is the most any U.S. nuclear worker is allowed without being sent home from work. And the 1,000 millisieverts per hour means that if one stayed near that 24 hours they would receive 24,000 millisieverts which is considered a fatal dose by everyone in the nuclear industry on earth.