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Fukushima – Of course they found plutonium!

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The headlines have been screaming for the last day or two that plutonium was found on the ground outside the facility. Well duh! Plutonium is everywhere, compliments of ours and Russia’s atmospheric bomb testing. I can go into the woods behind my cabin where the earth hasn’t been disturbed for probably 100 years and find Plutonium. Cs-137 also.

In this instance after they analyzed the samples in the lab they determined that the Pu came from one of the reactors. By looking at the Pu-238 to 239/240 ratio, one can tell whether the Pu came from a bomb or from a nuclear reactor. There is much more 240 in reactor Pu.

It’s all academic anyway since the amount found was so small. The concentration in my back woods is probably higher.

Plant Status

Probably the best status information available to us civilians is the IAEA status update page. The executive summary is that things have pretty much stabilized with the exception of the Unit 4 Spent Fuel Pit and the water in the turbine building situation.

I continue with my opinion that the #4 Spent Fuel Pit is damaged and is leaking water. Given the amount of water they’ve pumped into the pit, if there were no damage it should be just about full. As is, all they can hope for is to keep the fuel as cool as possible to preclude any more cladding failure and to reduce the emission of volatile isotopes, mainly Cs-137 and I-131.

I’ve changed my opinion about the status of the core in Unit 2. I previously thought that the core might have melted through the reactor vessel. On yesterday’s status matrix, the IAEA is listing the pressure vessel as stable as indicated by a stable pressure reading.

The important thing to note is that they think that all three cores remain partially uncovered. That accounts for some the I and Cs release. If the cores were covered then the two would combine chemically as I’ve described earlier and would not be be escaping into the air.

The IAEA update lists the volume of water being pumped into each reactor, a very modest 30 gallons per minute. That’s probably enough to prevent any further fuel damage but not enough to make up for boiling losses which is why I suspect that the cores remain uncovered. This is all speculation, of course, since no one and no robot has yet to enter any of the units to look around.

The matrix lists unit 2’s containment as probably damaged. This is indicated by the atmospheric pressure in the containment and by the release of radioactive material. There are several theories as to how this happened. One is that there was a hydrogen explosion inside the torus. I’m having a little trouble with that one because the reactor building and torus are inerted with nitrogen during normal operation precisely to prevent any build-up of hydrogen from burning. It’s hard to imagine enough air getting into the torus in the short time between the power outage and the “loud noises” heard coming from Unit 2. This is one where we’ll just have to wait and see.

The other big question is where the water in the turbine building came from. It’s radiologically very hot so it’s been in contact with damaged fuel. Hard to tell where it is flowing because of the unknown amount of damage to the buildings from the earthquake. Whatever the source, it’s a significant problem for the on-site people and will impede later clean-up efforts because the turbine building basement will be so contaminated.

Decontaminating that much water will be a huge job in itself. The smart thing to do would be to load it on a barge, ship it out to the middle of the ocean and dump it. Media pressure probably won’t permit that so they’ll probably have to install some sort of demineralizer system. And then deal with the very hot resins.

Off-site Radiological Conditions

The off-site conditions are amazingly good, considering all. The ambient radiation even in the Fukushima prefecture is at or barely above normal background readings. Contamination readings are similarly low, with most measurements being below the 2.7 nanoCurie per square meter limit set for infant exposure. As of today all drinking water restrictions (which I though to be excessive in the first place) have been lifted.

Over here in the US, the media has predictably been screaming about iodine being detected even on the east coast. While technically true, the amounts are at the limits of detectability and do more to demonstrate the spectroscopist’s capabilities than anything.

You don’t have to believe the media or even me. The EPA has put up a site that lets you see in real time the results of their RadNet network of fixed monitoring stations. These stations were installed in the post-TMI era to monitor US nuclear plant emissions. You can pick most any site and see that the detected activity has remained steady at pre-accident background levels or in some cases decreased. This ebb and flow of background readings is normal and is accounted for by atmospheric conditions.

Below the graphic is a section headed “Air Filter and Cartridge Results”. There is a PDF document there that lists long term sampling results from selected sites.

Whereas the fixed stations sample continuously and so the collection time is fairly short, the filter and cartridge measurements sample for very long times which serves to amplify the sensitivity of the measurement. If they draw 1000 liters of air through the charcoal filter, that amplifies the sensitivity of the measurement in picoCuries per liter by 1000 times over a one liter sample.

If you look at that chart you’ll notice that most of the results are in fractions of picoCuries per liter. These readings are at the edge of detectability, essentially background.

Media

It continues to amaze me that the media refers to this as a “nuclear disaster” while practically ignoring the real disaster caused by the earthquake and tsunami. An even that results in only 1 death and only a few injured is not a disaster.

In closing this post let me take a moment for another prayer for all those killed and injured by the real disaster – the earthquake and tsunami.

Posted by neonjohn on April 1st, 2011 under Energy, Nuclear


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