Japan worst-case scenario unlikely to cause catastrophic radiation release: expert

Mar 17, 2011

While exposed spent fuel rods at the failing nuclear reactors in Japan pose new threats, the worst-case scenario would still be unlikely to expose the public to catastrophic amounts of radiation, says a University of Michigan nuclear engineering professor who is an expert on this particular kind of reactor.

"For the public, I don't believe it would be much higher than two additional chest x-rays," said John Lee, a professor in the Department of and Radiological Sciences, citing the results of the Three Mile Island accident.

While the event appears to have progressed beyond Three Mile Island, Lee said that during that 1979 incident in Harrisburg, Penn., two chest X-rays were the worst experienced by plant workers. The public was exposed to much less.

Lee worked at General Electric during the time the company was making the type of boiling water reactor at the Fukushima plant. His book, "Risk and Safety Analysis of Nuclear Systems," will be published in May.

Spent fuel, which is fuel that has already been used but still retains a level of radioactivity, is a new concern, says Thomas Downar, a professor in the Department of Nuclear Engineering and Radiological Sciences.

"The worst thing that could happen now is the fuel rods could be exposed to the air and that could be, then, down to our last barrier," Downar said. "We could not have a recriticality, or a . It's physically impossible in this kind of system."

Lee and Downar are among the professors in the No. 1-ranked U-M Department of Nuclear Engineering and Radiological Sciences who are studying the technical issues involved in the emergency situation in Japan.

While the researchers understand that the situation is serious, they stress that a "meltdown" does not necessarily mean a major release of harmful radiation, and that the situation, while dire, is still more a kin to Three Mile Island than . A Chernobyl type of explosion is impossible in these plants, Lee said.

The new generation of nuclear reactors in the United States, the researchers say, are equipped with "passive" technologies that allow them to be cooled even during power blackouts. Water does not need to be pumped in, which has been a challenge in Japan.

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drivin98
3 / 5 (2) Mar 17, 2011
This assessment would seem to conflict with that given by the chairman of the U.S. Nuclear Regulatory Commission Gregory Jaczko in congressional testimony.

Jaczko believes there is little or no water in the pool storing spent nuclear fuel at the Unit 4 reactor, leaving fuel rods stored there exposed and bleeding radiation into the atmosphere.

Being spent fuel rods, (and I've heard it said that this pool might have had the relatively fresh fuel rods from number 4 core dumped into it immediately following the earthquake) these contain plutonium, cesium and other radioactive elements.

With the efforts to bring the situation under control looking like a succession of "Hail Mary passes", things certainly seems a lot more serious than nuclear proponents are willing to admit.
ryggesogn2
2.3 / 5 (3) Mar 17, 2011
Does anyone care to mention that ALL fuel rods at ALL US nuclear power plants are stored in pools of water on site?
The fight at Yucca Mtn. NV has been to slowly strangle nuclear power in the USA.
Finland is now constructing a series of underground storage facilities for their nuclear waste.
Styrge
1 / 5 (4) Mar 17, 2011
"We could not have a recriticality, or a nuclear explosion. It's physically impossible in this kind of system."

Even subcritical cores melt through every structure once in total meltdown. (It has already propably occurred already.) Suppose two of the molten cores drift into a same pit? That would exceed the critical mass and indeed the consecuense could be an atomic explosion. Unlikely, but by no means impossible.
Temple
5 / 5 (1) Mar 17, 2011
Jaczko believes there is little or no water in the pool storing spent nuclear fuel at the Unit 4 reactor, leaving fuel rods stored there exposed and bleeding radiation into the atmosphere.


One must carefully understand the difference between 'bleeding radiation into the atmosphere' and emitting radioactive particles into the atmosphere.

Radioactive particles can be dispersed by the wind and ingested through the now-contaminated air/water/food. These particles then become part of you, constantly emitting radiation into your body. That is very, very bad.

The radiation emitted from the radioactive material travels in effectively a straight line, and unless you are quite close to it (and unshielded), you will never encounter it.
Modernmystic
1 / 5 (1) Mar 17, 2011
Jaczko believes there is little or no water in the pool storing spent nuclear fuel at the Unit 4 reactor, leaving fuel rods stored there exposed and bleeding radiation into the atmosphere.


And this has nothing whatsoever to do with how safe the REACTOR design is or whether or not it can fully meltdown or create a "Chernobyl" type of incident.

PinkElephant
4 / 5 (4) Mar 17, 2011
And this has nothing whatsoever to do with how safe the REACTOR design is or whether or not it can fully meltdown or create a "Chernobyl" type of incident.
It has everything altogether to do with a "worst-case scenario" and "catastrophic radiation release" -- as per the title of the article above.
Skeptic_Heretic
5 / 5 (3) Mar 17, 2011
Does anyone care to mention that ALL fuel rods at ALL US nuclear power plants are stored in pools of water on site?
The fight at Yucca Mtn. NV has been to slowly strangle nuclear power in the USA.
Finland is now constructing a series of underground storage facilities for their nuclear waste.

Try reading up on the reality of what you're referring to as "waste".
omatumr
3.4 / 5 (5) Mar 17, 2011
The facts are just this:

1. Most energy is stored against repulsive forces as rest mass in the extremely tiny nucleus:

V(nucleus)/V(atom) = 0.000,000,000,000,001

2. Mankind must therefore learn to use nuclear energy safely or relinquish our insatiable appetite for energy.

3. Earthquakes of Magnitude ~9 are rare, almost impossible to plan for, but highly destructive.

4. The technological skills of the Japanese are great, but severely tested by present events

Those are issues that will need to be considered when the next set of nuclear reactors are designed.

With kind regards,
Oliver K. Manuel
Skeptic_Heretic
not rated yet Mar 17, 2011
Well, they got electricity back to the reactors. Now we wait to see if the pumps kick off. Pressure is reported to be dropping.
dan42day
5 / 5 (1) Mar 18, 2011
"We could not have a recriticality, or a nuclear explosion. It's physically impossible in this kind of system."

Even subcritical cores melt through every structure once in total meltdown. (It has already propably occurred already.) Suppose two of the molten cores drift into a same pit? That would exceed the critical mass and indeed the consecuense could be an atomic explosion. Unlikely, but by no means impossible.


Two cores that would exceed critical mass for a nuclear explosion would not be able to approach each other fast enough under the influence of gravity alone, to avoid a nuclear "fizzle" and would not explode as weapons are designed to do.
Modernmystic
5 / 5 (1) Mar 18, 2011
And this has nothing whatsoever to do with how safe the REACTOR design is or whether or not it can fully meltdown or create a "Chernobyl" type of incident.
It has everything altogether to do with a "worst-case scenario" and "catastrophic radiation release" -- as per the title of the article above.


No it doesn't. The waste and the reactor are two separate issues. Try actually READING what I wrote instead of what you wanted me to write.

I agree the waste issue could be a problem, the reactor simply can't. Unless they have another Earthquake and it cracks the outer containment...
Zephyr311
3 / 5 (2) Mar 18, 2011
Well, I'm sorry to hear that the worst case scenario, like always, is hype and fearmongering. Just when many were getting good and hysterical, the faux danger has subsided...*eye roll* No worries--there's still lots to freak out over if we look...the fear addiction will be fed...
PinkElephant
1 / 5 (1) Mar 18, 2011
Try actually READING what I wrote instead of what you wanted me to write.
Try actually commenting on-topic, rather than making spurious posts that run off on unrelated tangents.
Moebius
3 / 5 (2) Mar 20, 2011
Off topic but someone mentioned Yucca mountain. In my opinion Yucca mountain is a disaster in the making. We can't even bury a gas tank at a gas station without having to dig them up every few years because of leaks. Burying nuclear waste is nothing but hiding a problem for future generations to deal with and it might be a big problem because it is buried. This stuff is going to be dangerous for so long it needs to remain accessible, not potentially inaccessible.
omatumr
3.5 / 5 (2) Mar 20, 2011
Burying nuclear waste is nothing but hiding a problem for future generations to deal with and it might be a big problem because it is buried.


You are on target, Moebius. I agree.

Radioactive "waste" from nuclear reactors is, in fact, a very concentrated source of energy and should not be discarded!

It would make sense to REQUIRE all radioactive "waste" from a nuclear reactor to be:

a.) Encapsulated so it doesn't leak, and then
b.) Used to heat water, generate steam, so
c.) Any leaks could be detected and fixed,
d.) Not buried under Yukka mountain or anyplace else out of sight for future generations to deal with.

With kind regards,
Oliver K. Manuel


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