Fukushima Technical Discussion

[tok-tokkie]

Pup,
If the fuel melts the rod covering and flows down to the bottom of the pressure vessel can it melt the pressure vessel? If it does melt the steel will it be contained by the concrete? How long did it take for Three Mile Island to cool down so that it could be sorted out?

[Pup]

Pup,
If the fuel melts the rod covering and flows down to the bottom of the pressure vessel can it melt the pressure vessel?

If we're talking theoretically, yes, if they were to just just walk away and do nothing. Obviously at Three Mile Island, it didn't; and at Fukushima, even less likely. Even theoretically, it's on the fringe of what could happen. It may even be a disproved myth; I'd have to read more.

How long did it take for Three Mile Island to cool down so that it could be sorted out?

That's a tricky question. Cleanup started at TMI five months after the accident, but they didn't actually remove the fuel until 14 years later. Here's a chart of the decay heat at the reactors which will give you an idea of how dramatically the heat falls when the core is shut down and how gradual they cool from there on...



Safe to say that the effected reactors won't be operational again for a long, long time - if ever. To keep it in perspective, though - TMI is still operational; Harrisburg is still inhabited; Hershey still makes chocolate.

[Dragonfly]

Thanks.
I didn't mean nuclear explosion of course. Just the possibility of further heat generation.

Addition:
This link shows Overlaid aerial/space pictures before and after the quake.
On one of them is one of the power stations and it seems Pup is right diesel units are in pits. The picture is taken at an angle and shadows are more definitive.
Just drag the mouse across the pictures.

[WhiteBlue]

I'm a bit less optimistic that Pup's opinion on the helicopters is correct. It was reported that the heli pilots are not allowed to operate in 50mSv/h + environment and that the plume above #4 reactor was by far exceeding that limit. For all we know it could have several hundreds mSv/h.

I think that alternative methods like using riot water sprayers or manually brought in fire fighting hoses would be facing the same and even more problems as the workers probably would come closer to the heat of the boiling pool. Ultimately we just don't know.

I agree that the #4 fuel pond is the most concerning issue since no inhibitors based on boron are mentioned as available. A molten core would most likely have the alloys of the moderator rods and boric acid in the mix which would suppress the chain reaction. If the cladding of the fuel rods in the pool fails you get a core melt without any moderation. The fuel puddle could burn it's way through the reactor building.

I'm not sure how much material they have in those pools. I think one load is over 100 tons and they are supposed to have 4-6 loads there. It sounds like a lot of stuff that you don't want to see on fire.

[manchild]

http://www.chron.com/disp/story.mpl/ap/ ... 74952.html

NRC: No water in spent fuel pool of Japan plant

© 2011 The Associated Press
March 16, 2011, 2:58PM

WASHINGTON — The chief of the U.S. Nuclear Regulatory Commission said Wednesday that all the water is gone from one of the spent fuel pools at Japan's most troubled nuclear plant, but Japanese officials denied it.

If NRC Chairman Gregory Jaczko is correct, this would mean there's nothing to stop the fuel rods from getting hotter and ultimately melting down. The outer shell of the rods could also ignite with enough force to propel the radioactive fuel inside over a wide area.

Jaczko did not say Wednesday how the information was obtained, but the NRC and U.S. Department of Energy both have experts on site at the Fukushima Dai-ichi complex of six reactors. He said the spent fuel pool of the complex's Unit 4 reactor has lost water.

Jaczko said officials believe radiation levels are extremely high, and that could affect workers' ability to stop temperatures from escalating.

Japan's nuclear safety agency and Tokyo Electric Power Co., which operates the complex, deny water is gone from the pool. Utility spokesman Hajime Motojuku said the "condition is stable" at Unit 4.

[manchild]

http://www.mediaite.com/tv/japans-nucle ... ediaite%29

Japan’s Nuclear Crisis: ‘There Is A Recognition This Is A Suicide Mission’

by Mark Joyella | 4:55 pm, March 16th, 2011

U.S. officials are increasingly alarmed at the way Japan is handling its ongoing nuclear crisis, with one official telling ABC’s Martha Raddatz “They need to stop pulling out people—and step up with getting them back in the reactor to cool it. There is a recognition this is a suicide mission,” the official said.

There is growing concern in the U.S. that the situation in Japan is reaching a critical turning point, and if officials in Japan cannot get the nuclear plants under control within the next 24 to 48 hours, there could be a situation that will be “deadly for decades.”

Other world energy leaders told Raddatz the results of a failure to seize control would be a catastrophe:

“There is talk of an apocalypse and I think the word is particularly well chosen,” European Union’s energy commissioner Günther Oettinger said today, according to various reports. “Practically everything is out of control. I cannot exclude the worst in the hours and days to come.”

http://www.ottawacitizen.com/news/Japan ... story.html

[WhiteBlue]

The magnitude of the earth quake and the hight of the tsunami wave that Japan has faced this week was entirely predictable by the scientific knowledge and methods known to us and the Japanese for at least five years. People only need to read the respective documents by the US Reactor Safety Commission and the US National Oceanic and Atmospheric Administration to understand that. The responsible people in Japan chose to ignore the obvious risks because the probability deemed to be acceptable for a time span of 1,000 years. They failed their responsibility to protect their customers, their constituency and their students by doing the job they were paid for. This is undeniable fact and not speculation. Predictable but small risks are not tolerable in a high risk technology like nuclear power generation. If the consequences of failure are potentially as grave as scale 7 nuclear accidents one occurrence in 1,000 years is not acceptable.

The question which arises from the Fukushima disaster is simple. Are there other risks for all the nuclear reactors that have been deemed acceptable by people who are paid to look into these things? And have those experts lied to us to allow corporations to make more money? For me the answer is undoubtedly YES since I have studied the case of the oldest nuclear power plant that supplies my home with electricity.

This power station is located in the wider landing zone of a huge international airport with 1300 starts and landings of airliners per day. The plant has no protection against even the smallest of those aircraft crashing into the power plant in a simple air emergency. This is not even considering deliberate action like nine eleven. The design life of the plant is running out this year. Like Fukushima Daiichi #1 it was scheduled to be terminated and in the same way the running time was extended by corrupted or irresponsibly acting politicians. Members of the local Bavarian parliament have paid for an independent scientific risk assessment for that plant. The result was clear beyond any doubt that the 1969 design was completely unacceptable compared to the state of knowledge and the state of the engineering art. Exactly like at Fukushima the federal government extended the use of the plant from 2011 to 2018. The only explanation is greediness. We do not even need this plant in Bavaria since we are net exporters of electricity.

I don't have the time to check all the cases of older nuclear power plants and second guess the decisions of the responsible politicians. But I have the choice to support the party which is in federal government now or the party which would have switched the older plants off. For me there is no question what I will do to protect myself, my daughter and all my loved ones. From accident analysis in nuclear power plants we know many possible ways how these things can fail. It is not just earth quakes, tsunamis and air craft accidents. I want all those risks to be checked by trust worthy people and I want the consequences of such analysis acted upon swiftly and without the corrupting influence of the plant operators.

NHK live coverage have just confirmed that the radiation level at the #3 plant is now 3.7 Sv/h. It means that pilots and workers can only be exposed for minutes at a time. 3.7 Sv is considered to be lethal if exposed to for 60-90 minutes.

[forty-two]

Perhaps a silly question, but if the plant has lost all power, surely that would include instrumentation normally used to monitor temps, pressures, water levels etc.

Granted, this would only require a tiny amount of current by comparison to the pumps, but maybe this is the reason for some of the apparent guesswork going on, and the inconsistency of the US official's statements and those of TEPCO?

Why didn't they connect a ship-container sized generator to each unit on Sunday (or three or four per unit, whatever is reqired)? I think one of the biggest manufacturers of these is actually Hitachi, so surely some could have been sourced "locally" and flown/shipped/dragged in somehow?

I wonder in fact if the pumping equipment (hoses, nozzles, plumbing etc) might ALSO have been damaged by the Quake/Tsunami/Explosions and even if the power were hooked up it wouldn't help.

[segedunum]

I see the reporting hasn't got any better since Chernobyl.

They know exactly what the radiation levels are around the plant and exactly what they are putting those helicopters into. We don't have a situation at Chernobyl where you had people on real suicide missions handling radioactive material and physically dumping it by hand back into the reactor. That all came about because the reactor itself didn't save the people running it from their own stupidity, but that's another story.

We're focusing on the wrong disaster here I feel.

[marekk]

A little shaky video from today, cooling systems doesn't look healthy, connecting external power sources will be just a part of job.
http://t.co/L63M9Lu

[marekk]

The EU's energy chief has said that the "stress tests" European nations will conduct on nuclear reactors will likely expose safety shortcomings in some of them. "I think that the stress test that we want to conduct on all the nuclear reactors will show that not all of them meet the highest safety norms," EU energy commissioner Guenther Oettinger told Franco-German TV station Arte. EU states have agreed to conduct voluntary tests in the second half of the year on Europe's 143 reactors to determine their ability to withstand earthquakes and other disasters.

First good idea of EU in years. Very rare. Good news for WB and all of us.

[Pup]

Populist grandstanding. Germany's needless reactor shutdown is pure theater that's going to cost them almost $4 billion.

[manchild]

Since the other thread fell victim to our seemingly bipolar moderating, let's see if we can't start anew - this time with neither nuclear promotion nor fear-mongering, and hopefully with no mention at all of shark fins, iPods, or Gaia.

Populist grandstanding. Germany's needless reactor shutdown is pure theater that's going to cost them almost $4 billion.

[Pup]

Good for the goose, rainbow boy. Should we look back among your posts? You're starting to sound like a Ferrari fan - OMG, cheaters!

[autogyro]

Sorry if my posts on this issue are not technical as such Richard.
I think it should be obvious by now that the nuclear industry and the governments responsible for that industry world wide have been lieing to everyone.
It is therefore very difficult to know who to believe on the technical statistics and safety figures.
WB has researched his own area and I believe we should all do the same.
Checking reactors and delaying building them is hardly a knee jerk reaction is it.

Like most of us, I realise that nuclear power cannot be suddenly turned off.
Just let us consider the tecnical facts and hopefully there will be some sensible suggestions on how to replace nuclear power over as short a period as is possible.

The comments from those with obvious vested interest in the technology should not be believed at least of that we can be sure.