MOX a concern in Japan reactor

Mixed-oxide fuel more difficult to control, experts say

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Scientists warned this week of yet another complication in Japan’s  nuclear crisis: O ne of the doomed reactors is loaded with mixed-oxide fuel that contains plutonium.

A man carries a heat blanket as he leaves a radiation emergency scanning centre in Koriyama, Fukushima Prefecture, Japan, Tuesday, March 15, 2011 four days after a giant quake and tsunami struck the country's northeastern coast.   Associated Press
Associated Press
A man carries a heat blanket as he leaves a radiation emergency scanning centre in Koriyama, Fukushima Prefecture, Japan, Tuesday, March 15, 2011 four days after a giant quake and tsunami struck the country's northeastern coast.

“This sort of plutonium fuel is more difficult to control than uranium fuel,” said Arjun Makhijani, a nuclear scientist and  the  president of the Institute for Energy and Environmental Research.

The fuel, known generically as  MOX,  was made by nuclear giant AREVA in France, where MOX technology has been used for almost two decades.

The rods, made by blending small amounts of plutonium with traditional uranium, were loaded into  Unit 3 of the Fukushima Dai - ichi nuclear plant last September.

Makhijani said the unit contains 32 MOX assemblies , about 5 percent of the fuel now in the reactor, where an explosion this week kindled fears of a radiation release.

“With this fuel, the risks of accidental criticality are different,”  Makhijani said. “You have the same kinds of problems ; they are just more intense with plutonium.”

AREVA is also part of Shaw AREVA MOX Services – the group building the National Nuclear Security Administration’s $4.86 billion MOX plant at Savannah River Site.

The MOX fuels used in the Japanese reactor and several dozen others are a mixture of uranium and plutonium reprocessed from spent uranium, but the facility at SRS is designed to use weapons - grade plutonium from dismantled nuclear warheads to make fuels
usable in commercial nuclear  reactors.

The plant’s mission is to dispose of the weapons - grade material to prevent exploitation by terrorists. T he search for utilities willing to use the fuel when production starts in 2018 has moved slowly.

Currently, the Tennessee Val­ley Authority is evaluating the use of MOX fuel in as many as five of its reactors, and a Richland, Wash., utility is mulling
its use in one unit, but no formal user agreements have been signed.

Safety officials have pointed out that the problems in Japan were caused by the  combined effects of the earthquake and tsunami –  not by the type of fuel in the  reactors.

In an e-mailed statement Tues­day, a National Nuclear Security Administration spokesman said U.S. officials remain confident about the safety of existing programs.

“The American people should have full confidence that the U.S. has rigorous safety regulations in place to ensure that our nuclear power is generated safely and responsibly,” the spokesman said. “Information is still coming in about the events unfolding in Japan, but the  administration is committed to learning from Japan’s experience as we work to continue to strengthen America’s nuclear industry.”

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Little Lamb
49247
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Little Lamb 03/15/11 - 04:03 pm
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I don't think "accidental

I don't think "accidental criticality" is a concern to those workers in Japan trying to get water on the melted blob (you really can't call it a "core" any more). Just more fear-mongering from Arjun Makhijani. Don't forget that a light-water reactor loaded with only uranium fuel quickly builds in a significant amount of plutonium from neutron capture of U-238.

SCEagle Eye
959
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SCEagle Eye 03/15/11 - 05:47 pm
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Spent uranium fuel reaches

Spent uranium fuel reaches only about 1% plutonium. MOX goes into a reactor with about 5% plutonium, making the reactor harder to control from the start. MOX made from purer weapons-grade plutonium has never (that's never) been used on a commercial scale and the test of it in a Duke PWR reactor was aborted after 2, rather than 3 irradiation cycles. A MOX test in TVA's Browns Ferry reactor, the same model as the exploding Japanese reactors, will take a full 6 years, if a place can be found to make weapons-grade MOX for those tests. (There is no place in the world available.) Weapons-grade MOX has never (never) even been tested in a BWR. MOX in an exploding reactor design anyone? Please speak up.

jackragg
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jackragg 03/15/11 - 07:01 pm
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Everybody's a nuclear expert

Everybody's a nuclear expert all of a sudden. As someone who is in the business, but by no means an expert, I know enough to say that the type of fuel being used makes little difference at this point. Also MOX is MOX. The term "Weapons Grade MOX" is just plain silly. And as far as Duke's tests go it's suspected in the industry that they deliberately botched it in order to hold out for Government subsidies. That's really why there's no customers so far. MOX is more expensive to use. MOX fuel has been used succesfully in other countries for years. A tsunami/earthquake is the culprit here. Not the fuel.

SCEagle Eye
959
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SCEagle Eye 03/15/11 - 09:48 pm
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jackragg - Are you an expert

jackragg - Are you an expert or did you just become one? Please present your qualifications.

jackragg
0
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jackragg 03/15/11 - 11:47 pm
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If it matters I'm in Nuclear

If it matters I'm in Nuclear Quality Assurance. And if you read my post I don't claim to be an expert. I would like to think that I'm more than qualified to make an educated statement though.

MOXrocks
53
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MOXrocks 03/16/11 - 06:59 am
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SCEagle Lies - present your

SCEagle Lies - present your qualifications other than being a professional fear-monger and spinster. Let's guess, eco-activist that has nothing better to do but sit around and write psuedo-scientific lies about MOX and the nuclear industry?

Bubba
152
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Bubba 03/16/11 - 07:05 am
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From his bio.. "Arjun

From his bio.. "Arjun Makhijani is President of the Institute for Energy and Environmental Research in Takoma Park, Maryland." There are a lot of nuclear experts in your own backyard and yet Robert goes to someone from Maryland for an opinion. As if that weren't enough, also from his bio... "He is the author of Carbon-Free and Nuclear-Free: A Roadmap for U.S. Energy Policy (2007)." He is as biased as me, we’re just 180- degrees out of phase with one another. It would have been fairer to disclose in the article that this is a person who envisions a nuclear free United States, or so his book title suggests. Try and find an expert without bias next time, or at least don't make us have to point it out. Good news and non-imflammatory headlines don't sell papers, eh?

ScottP88
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ScottP88 03/19/11 - 10:00 pm
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to Little Lamb: One thing

to Little Lamb: One thing that TMI showed us was how that molten mass in the bottom of the reactor did in fact start a second criticality. Fule melted twice at TMI...once at the top of the fuel assemblies after being uncovered, and again at the bottom of the reactor.

There are several mechanisms at the Fukushima reactor which can cause the fuel to go critical again.

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