By Wednesday morning Japan time, the BBC confirmed that a "criticality event" was being reported in the No. 4 fuel pond after it caught fire. The fire was initially thought to have been extinguished, but then reignited. Tokyo Electric Power, which has come in for intense criticism for failing to keep government officials informed on the condition of the Fukushima reactors, has now admitted that "criticality" was reached during the first fire, and, according to reports, “The possibility of re-criticality is not zero."
"The explosion at the spent fuel pond at reactor No. 4 was a criticality explosion," Moglen asserted, "which means that the fuel in that pond has begun to interact on a nuclear level--that there was a nuclear chain reaction going on in the pond."
A "criticality event" means that the melted fuel rods accumulated enough mass to exceed the "critical" stage and start a nuclear chain reaction similar to the controlled reaction in a normal reactor. Without a containment vessel, the nuclear reaction emits large amounts of radiation while potentially releasing radioactive particulate directly into the air.
"The spent fuel ponds are even more dangerous than the inside of the reactors because the fuel pools are open to the air. At least there is a containment vessel around the reactor cores," said Moglen. "All six pools are in jeopardy, since they need to be constantly supplied with water to replace that which the fuel rods are constantly boiling off."
So far, nuclear reactions have only been reported in the No. 4 reactor fuel pond, but Tokyo Electric Power said fuel pools in the Nos. 5 and 6 reactors are becoming superheated, and that the No. 3 fuel pool is on fire.
"It’s like a cascade event, resulting in crisis after crisis without being able to resolve any of them," Moglen said.
To watch and hear experts discuss Japan's nuclear crisis, please visit this page on EE Life.
Oh if the tragedy extends to nuclear reactors, it would be beyond controllable. Why all this happened in Japan? I really feel sad for people of Japan. hope the world bank and united nations are supporting with open arms.
The U.S. media has recently discovered and reported that we have over 65,000 tons of spent fuel rods here in the U.S., and the vast majority of it is stored in on-site pools -- exactly as in Fukushima.
Even if the Yucca Mountain Nevada storage facility idea had not been abandoned, we already have more nuclear waste than that facility was intended to store, and we generate another 2,200 tons every year.
Unlike some countries, we don't reprocess our spent fuel, which could dramatically reduce the quantity -- from what I have read, by as much as 75%.
So why don't we reprocess it? Because reprocessing costs money, electricity rates are regulated, and electric utilities aren't in business to lose money.
It was my understanding (read about - not seen with my own eyes) that the generators were in the basement and got overwhelmed by the Tsunami. I also read that there were many (read here years worth) of spent fuel rods stored "on-site". I can appreciate the issues of disposal, transportation, and costs associated with spent rods as very significant, clearly we should develop safe and effective methods of recycling, disposing of the spent rods in order to avoid further safety/radiation issues in future events.
I am not sure what to say about the emotions displayed in this thread. I understand that the inciddent is such that it incites emotions but at the same time we should all look at the facts and facts provoking questions. What caused the Diesels to not operate when they were suppose to? Were the DC batteries sized adequately to cope with such events? What lessons can be taken from these events to prevent such a catastrophe from happenning again? Nonetheless the above questions do not undermine the events that have ensued. In no way in my opinion should the release of any radioactive particles/gases should be taken lightly. The appropriate actions shall be taken to ensure the safety of the people in the vicinity of th reactors and elsewhere. Unfortunately now a days journalists have become Nuclear experts, which is a dangerous prospect. Journalists are reacting to this incident as they were when the health care bill was being drafted. A highly reliable source for up to date facts/information on the Japan's incident, please visit http://www.nei.org/.
Just adding to your last point about coal fired power plants:
A recent study estimated that "...fine particle pollution from existing coal plants is expected to cause nearly 13,200 deaths [in the U.S. alone] in 2010. Additional impacts include an estimated 9,700 hospitalizations and more than 20,000 heart attacks per year."
We must put into perspective the most likely facts surrounding this nuclear power incident:
1. The plant was probably built and maintained to the highest possible and REASONABLE standards. (I don't have to mention on an engineering forum the concepts of trade-offs even when one parameter is cost.)
2. Without continuing to introduce vast amounts of CO2 into the atmosphere (and its attendant problems, whatever you perceive them to be) the ONLY timely and cost efficient source of the quantities of electricity needed in the world is nuclear energy.
3. Accidents (many fatal) are associated with any human activity in which uncontrollable variables are involved. EVERY year in the US some 20 to 60 coal miners die and in China that number rises to over 2k. Yet, we have no outrage over coal fired power plants as we might nuclear even if one soul perished. We must begin building nuclear plants as safely as possible, inland (with unsightly cooling towers) if necessary, in order to avoid a serious economic crisis.
Thanks for the info. As you may have gathered, some of the comments were directed at a poster UBM-something, whose religious comments (mostly quoting a few verses of Revelation) seem to have been removed...
As I write Japan seems finally to be bringing the reactors under control, so lets hope futher disaster has been averted.
If reactor design and safety procedures improve as a result of this, some good will have come out of it.
Why are you all wasting your time with theoretical religion? Isn't physics hard enough?
" a nuclear reaction has begun in a spent fuel rod pond"
This is clearly not true. The nuclear reactions that have been decaying all along are not being cooled sufficiently now.
And no - radioactive iodine is not the nastiest substance known. Used in liew of surgery for removal of a hyperactive thyroid.
Plutonium, the longest lived of these, is an alpha emitter. Very very short range. Just don't inhale the dust.
Radioactive cesium, soluble in water as I recall. Rain? Also a short half life, couple months isn't it?
Sr 90. Very nasty. Also not likely to go far from the site unless the smoke plume gets really high. Worry about what is, not what can be wildly imagined.
The comment above was correct:
"It's not possible to have a rational argument with an irrational person"
Until you can answer the questions I posed above, I will take it that you cannot do so. Calling my questions stupid does not help. The only stupid question is one that is not asked, and clearly you are not interested in enlightening an ingnoramus like myself.
I do believe in a higher being, and will entertain the possibility that said higher being has some responsibility for the natural disasters recently, so I had some sympathy for your points at first. But your refusal to have a rational discussion does your position no good at all.
David Patterson, known for his pioneering research that led to RAID, clusters and more, is part of a team at UC Berkeley that recently made its RISC-V processor architecture an open source hardware offering. We talk with Patterson and one of his colleagues behind the effort about the opportunities they see, what new kinds of designs they hope to enable and what it means for today’s commercial processor giants such as Intel, ARM and Imagination Technologies.