A "big boom" is not in the cards, if you're talking about an actual nuclear explosion. If you're talking about another hydrogen explosion like the ones we've already seen, then you could be correct.

In order to cause an actual nuclear explosion, you need to cause a supercriticality, which it turns out is quite hard to do without exacting science and material refinement.

It sounds like they are now dealing with prompt criticality due to the melting of fuel. While it's really *really* not good, it's not going to vaporize everything within a mile and cause a mushroom cloud.

By big boom, I mean big dirty bomb. An underground steam explosion following a complete core melt could be pretty nasty.

There are going to be lots of little nuclear reactions there for a long time. I'd agree that an actual nuclear explosion is unlikely, but a month ago this whole thing was supposed to be extremely unlikely. Nothing would surprise me at this point.

No April fools joke this!
And what pray tell is going to be done with the radio active water being collected in that barge?
Meanwhile more mealy mouthing announcements from those "in charge" that things aren't that bad...
Clean, Safe,....and Cheap nuclear power?????

Update: TEPCO now says the ground water under the plant is contaminated with 10,000 times the amount of iodine and other stuff at a depth of 15 meters, but don't worry it will be alright.

Could it all be sent to the bottom of the mariana trench-seven miles deep in the pacific?

Does anything that deep ever get circulated?

I'm not a scientist but that building looks damaged to me.

I'm especially disappointed that General Electric's American name is on these plants. Clearly they were not built to withstand a really big earthquake, particularly the cooling pools. And everybody knows that Japan is earthquake country.

Nuscale Power in Corvallis uses passive cooling in their new design. Would passive cooling have saved the plants in Japan?

From the ABC story: "Workers will soon have help from a U.S. company, as the world's largest concrete pumps are being shipped in from the United States.

They will first be used for spraying water from a greater distance than anything on site right now,and they might eventually be used to coat the reactors in cement and bury them for good."

About time. And don't bother with the water, just start with the concrete.

Would passive cooling have saved the plants in Japan?

Yes. The major issue here is the loss of coolant, which caused the whole mess. Had the coolant pumps continued running, the reactors would have powered down safely as designed. No partial (or full, who the heck knows) fuel melt, no hydrogen explosions, no seawater pumping and disposition of salt in the pressure vessel, fuel cladding fires, etc.

All 4th generation reactor designs incorporate passive cooling techniques - be it using coolants that can't physically boil in the environment they are exposed to (liquid lead / bismuth eutectic cooling, gaseous helium cooling) or with schemes that don't require external power generation to keep the core cool post-shutdown.

The problem at this point, is that anyone designing such a system has a hard sell on their hands, way harder than it would have been a month ago. This is also the reason that the French company Areva, the largest commercial nuclear company in the world, is now sending supplies, equipment, and engineers to Japan to help out. Most, if not all of their contracts for new reactors are now on hold.

passive cooling

Ah, the new "safe" reactor design! Yes, those will be built -- as soon as everyone who's alive now is dead. The latest thing in 2111!

http://www.opednews.com/articles/Obama-s-Wrong-headed-Nucle-by-Karl-Grossman-110331-988.html
Excerpt:
The Nuclear Regulatory Commission is an unabashed promoter of nuclear power-never having denied a license for a nuclear power plant anywhere, anytime in the United States. In recent times it has been busy extending the operating lives of half of U.S. nuclear plants to 60 years, although because radioactivity embrittles metals in nuclear plants, they were never seen as operating for more than 40 years. But with no nuclear plant ordered and built in the U.S. since 1973, the commission has been seeking to keep the nuclear industry going, somehow. The commission and the nuclear industry have recently been seeking to extend the operating lives of the plants to 80 years. With this promotional stance, will the commission -make sure all of our existing- nuclear plants are safe?

Moving forward?

Long ago when I was at Edwards Air Force Base (on the Mojave Desert) they would spray a resin along the sides of the roads to keep blowing dust down. Worked somewhat. Made the dirt look not entirely unlike peanut brittle.

Note: I didn't claim that these new designs would work any better or more reliable, I'm just saying that passive cooling is a 'design feature' of 4th gen systems.

Please don't put words in my... errr... post.

Question:
Would passive cooling have saved the plants in Japan?
MSF:
Yes

Um, those are your words, MSF.

Would someone please correct me if I'm wrong.......On the 2nd day of this nuclear disaster, the United States Goverment offered coolent to the Goverment of Japan..And the reply was "your help is NOT needed at this time!"
Jack, I think you are correct to state that this disaster will be greater than Chernobyl!
New Jersey has the oldest working nuclear reactor in the nation. Oyster Creek has been churning out spent fuel rods for over 50 years now!.

Nuclear Meltdown 101