What "might happen" with the Japanese Nuclear plants?

[GreyGeek]

Re: What "might happen" with the Japanese Nuclear plants?

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I'm rather skeptical that there would be enough of either to be visible outside the building (especially from a distance). But if there would be, my bet would be that it is not Cherenkov radiation.

None the less, such a glow was seen and recorded, along with the Neutron and gamma ray emissions.

The main reason I'm not easily convinced of a nuclear explosion is that it is actually rather hard to get fissile material to explode (just putting a critical mass together won't be enough). It takes a bit of engineering to prevent a critical mass to go sub-critical before there is enough energy released to *explode* (of course one would need to define what constitutes an explosion)

They did that experiment at Los Alamos. It was called "Tickling the Dragon's Tail". Here is a photo of the test assembly:

...but if we're talking about an explosion strong enough to destroy a building, I just can't think of a way that could happen in the conditions of the reactor (I don't see where the pressure would come to keep any kind of "containment" sealed long enough, for example) or with the fuel used in nuclear plants (it's not enriched enough).

There are also too many variables involved in the two explosions to call the differences visible in explosions definitive evidence of a nuclear explosion.

I'm not saying it's impossible, just that I haven't seen enough evidence to overthrow my skepticism.

Of course, any kind of explosion in a failed nuclear plant is something one does not really want to see (they are not that great on functioning nuclear plants either).

I can imagine several scenarios where criticality under inadvertent containment can occur. But, my wife is calling and I have to go...

[kubicle]

Re: What "might happen" with the Japanese Nuclear plants?

I'm not saying the fuel couldn't go critical, neutron radiation is an indication for it...just that going critical doesn't mean the fuel would explode.

For an explosion, you'd need more enriched uranium (the fuel in light water reactors is only 3-5% 235U) and very high pressure (most exploding assemblies also use neutron reflectors), I still don't see how all of it could happen accidentally.

Criticality experiments use highly enriched uranium (>80% 235U) or plutonium and even these assemblies don't blow up when they go critical (starting the chain reaction is not the hard part, keeping it going is).

.....
I'm rather skeptical that there would be enough of either to be visible outside the building (especially from a distance). But if there would be, my bet would be that it is not Cherenkov radiation.

None the less, such a glow was seen and recorded, along with the Neutron and gamma ray emissions.

Haven't seen any (video) recordings, but the reports I've read talk about blue flashes (which would suggest ionized air glow and the presence of ionizing radiation, possibly from fission reactions). I would still say it's not Cherenkov radiation, as Cherenkov radiation and detectable neutron emissions are usually mutually exclusive (water is a very effective neutron shield, neutrons from fission will travel less than meter in water).

[GreyGeek]

Re: What "might happen" with the Japanese Nuclear plants?

You are correct in saying that the fuel pellets are not weapons grade, because over 90% of it is U238.

However, it is a MOX fuel, containing both U235 and Pu239, of Nagasaki fame. And, additional Pu239 can and is created when criticality occurs because neutrons from the fission of U235 are captured by U238 nuclei to form U239, which has a half-life of 23.5 minutes. Within 4 hours U239 would have converted to Pu239 via beta decay, converting a neutron into a proton to form Np239 (half-life 2.36 days, converted in 24 days) and another beta decay forms Pu239, so the reaction is self-enriching with regards to Pu239, which is the fissionable material of choice, and the most toxic element known. The more criticality the more Pu239 is produced.

In late June and July radiations levels dramatically increased, and Pu239 and Np239 were found 40km from Fukashima. The increase in radiation levels increasing again indicate that the criticality has occurred at least twice, or more. Lt. Gen. Burton M. Field, US Commander in Japan, said that the reactors exploded.

How much more is difficult to know because the Japanese government and TEPCO have been in collusion to suppress the truth about the level of the radioactive contamination. Slowly, as the truth leaks out, the levels are going up and up, and NISA says the Pu239 released is now 23,000 more than what was originally admitted to. On August 2nd of this year two locations OUTSIDE the Fukashima plant gave radiation readings in excess of 10 Serverts, which is lethal even with only a few minutes of exposure.

Interestingly, the University of Tokyo analyzed an explosion at reactor #4 and concluded that it occurred partly because huge amounts of hydrogen were produced in the process of water being dissolved by radiation in a boiling spent nuclear fuel pool. A video of the explosions shows the classic Hydrogen shock wave, just like #2, but it is followed by what looks like a lot of steam venting, as if out a RR steam engine smoke stack. The explosion is nothing like the #3, nor as violent. The big steam cloud is obvious. What is missing are chunks of building and metal being blown sky high.

An example of a reactor exploding due to steam generation after being put into a power excursion is shown here, when SPERT, a small test reactor, was terminated via this experiment. The event looked similar to the steam explosion in #4.

An interesting scenario is if an electrical grid failure occurs, regardless of cause (war, revolt, fuel shortage, terrorism) is shown in this National Geographic excerpt, which hypothesizes on what would happen to the planet if humans suddenly disappeared. This excerpt just show what would happen if a lot of power reactors after standby power generators ran out of fuel. Let's just hope the crazies don't start tossing nukes or destroy the electrical grid.

I also found this interesting account of a "grave digger" from Chernobyl, who described the red pine trees, dogs crossing with wolfs to create canines that were not afraid of humans but were extremely dangerous, etc...

[kubicle]

Re: What "might happen" with the Japanese Nuclear plants?

However, it is a MOX fuel, containing both U235 and Pu239, of Nagasaki fame. And, additional Pu239 can and is created when criticality occurs because neutrons from the fission of U235 are captured by U238 nuclei to form U239, which has a half-life of 23.5 minutes. Within 4 hours U239 would have converted to Pu239 via beta decay, converting a neutron into a proton to form Np239 (half-life 2.36 days, converted in 24 days) and another beta decay forms Pu239, so the reaction is self-enriching with regards to Pu239, which is the fissionable material of choice, and the most toxic element known. The more criticality the more Pu239 is produced.

The reaction is possible (and certainly happens), but you have to take into account that most of the neutrons escape (hence the neutron radiation) and that there will always be more U235 or Pu239 depleted due to fission than U239->Pu239 formed (otherwise the chain reaction would stop) so the amount of fissile isotopes doesn't actually increase (it would be the equivalent of perpetual motion).

The reaction can be (and is) used to get extra yield from nuclear fuel (using the "recycled" Pu239 as part of the reaction), but if the process would be "self-enriching", we could use all the U238 as nuclear fuel (spent 3% U235 nuclear fuel typically still consists of 1% U235, 1% of "recycled" Pu239, 3% fission products and 95% U238)...and every country in the world that has fission reactors would have an effectively endless supply of weapons grade plutonium.

And while the "recycled" plutonium can add to the yield of prolonged fission (such as in nuclear reactors) the reactions to turn U239 into fissile Pu239 are too slow to add to the yield of an explosion.

Lt. Gen. Burton M. Field, US Commander in Japan, said that the reactors exploded.

I don't think he meant *nuclear* explosions.

the most toxic element known

The most toxic element is likely Polonium. Both are similar alpha emitters, but Po210 is much more radioactive than Pu239. Of course both are quite harmless outside your body as alpha radiation doesn't penetrate skin (Pu239 releases significant amounts of penetrating radiation only when critical), but both are harmful inside your body even in relatively small amounts, especially when inhaled. 1 g of Po210 could *theoretically* kill 10 million people.

On August 2nd of this year two locations OUTSIDE the Fukashima plant gave radiation readings in excess of 10 Serverts, which is lethal even with only a few minutes of exposure.

To put fallout radiation risks into perspective, the average radiation people get from fallout (nuclear tests, accidents etc.) is negligible to the amount we get from natural (background radiation) sources, such as radon in the air, carbon-14 and potassium-40 we eat, cosmic rays etc. and other sources such as medical imaging. The radiation from nuclear accidents is significantly higher on-site and surrounding territory, but globally, even though accidents obviously raise the levels temporarily, people should be much more concerned about the level on naturally occurring radon in the air they breath every day (smoking is also a major radiation source).

[woodsmoke]

Re: What "might happen" with the Japanese Nuclear plants?

Radiation in Japanese baby formula, under the limits but... recalled.

to a certain extent, the use of the term "irradiated" is a correct useage and to a certain extent it is not.

http://globalspin.blogs.time.com/201...ors_picks=true

woodsmoke

[MoonRise]

Re: What "might happen" with the Japanese Nuclear plants?

Did anybody see the article on exactly what happened at the epicenter? The amount of earth that moved is amazing!! I couldn't imagine if that occurred on the surface of a continent.

[woodsmoke]

Re: What "might happen" with the Japanese Nuclear plants?

hi moonrise, could you provide a linky?

woodsmoke

[GreyGeek]

Re: What "might happen" with the Japanese Nuclear plants?

Did anybody see the article on exactly what happened at the epicenter? The amount of earth that moved is amazing!! I couldn't imagine if that occurred on the surface of a continent.

I saw that. It explains why the water went over the sea wall, as shown in that famous video of ships being swept over the wall. When it was built the sea wall designed to be 1 meter higher than an expected tsunami wave. What the designers didn't anticipate was that the shore on which the sea wall was built would sink more than 3 meters, making the sea wall useless.
http://www.youtube.com/watch?v=NW7vENdDu1o

[woodsmoke]

Re: What "might happen" with the Japanese Nuclear plants?

thanky GG
woodsmoke

[MoonRise]

Re: What "might happen" with the Japanese Nuclear plants?

Still amazing how much the Earth shifted!!!

[GreyGeek]

Re: What "might happen" with the Japanese Nuclear plants?

And by that much of the Japanese coast sinking by that amount it is the same as a skater pulling in their arms, causing them to spin faster because of the conservation of rotational momentum. So, Mother Nature shortened the day by more than a microsecond, allowing you to get off of work earlier!

[MoonRise]

Re: What "might happen" with the Japanese Nuclear plants?

I wish!!! Doesn't happen with me anyway.

[GreyGeek]

Re: What "might happen" with the Japanese Nuclear plants?

Fairewinds has a new video of a presentation by a civil engineer who specializes in radiation measurements.
http://fairewinds.com/content/new-vi...th-association

He discusses the different between exposure due to inhalation or absorbtion of "hot particles" as opposed to "total overall radiation", and why the Banana comparison isn't valid.

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The thing that concerns us the most currently about Japan, is that the means of testing radiation is still focussing on total radiation, and not focussing on hot particles. And we are still using things like circular evacuation zones. We actually took people from safe areas that were 20 kilometers from the site and moved them into much more contaminated unsafe areas that just happened to be further away. This was just done without regard to what the actual scientific data should be telling us.
...
So the question is: Is the risk based on hot particle exposure different from that based on a total body exposure. The way to answer this question is, we always say, that if you compare like amounts of radiation, is the hot particle different from the total body.

(Questioner interrupts and continues his question: Are there epidemiological studies?)

Marco Kaltofen: Yes. You definitely want to go there. The important thing in that question is that little qualification of "the same amount of radiation." Because a hot particle has a very long residence time and because it exposes specific tissues for a long period compared to an external or photon dust like gamma radiation, you tend to get a lot of concentrated radiation with a long residence time and your total radiation exposure tends to be higher. When you correct or normalize for that radiation exposure, when you artificially raise your external dose to the same as the hot particle, in fact you find that the hot particle is a little less dangerous, because your body acts as shielding; your tissues where the hot particle is, shield the rest of your body from that radiation. So the epidemiological studies show a slightly reduced dose. But you have added that huge fudge factor where you have assumed that the external uniform dose was as big. And that is really hard to do with a short term dose compared to the years you could have a hot particle in your body. So if you use that fudge factor, you can convince yourself that it is OK. But in real life, the hot particle tends to create a long term exposure where total radiation goes up, more than you would think, just based on the size of the particle.

[woodsmoke]

Re: What "might happen" with the Japanese Nuclear plants?

Enjoy GG!

http://www.techspot.com/news/46647-g...reet-view.html

woodsmoke

[GreyGeek]

Re: What "might happen" with the Japanese Nuclear plants?

Thanks!

When I see damage like that in Japan and think about how their monoculture combined with their socially oriented culture controlling behavior in such a crowded country, it explains how they are managing to contain the social damage as they repair the physical damage.

Comparing that even with the hurricane over New Oleans and the resulting behavior and "clean up" makes one wonder how the USA would respond to, say, an earthquake along the East coast of an equal magnitude.