Fukushima Meltdown Might Have Come With Earthquake, Not Tsunami

formfeed writes "As the data from the Fukushima reactor is being reviewed it looks like the meltdown happened much earlier: '[T]he fuel rods in the No. 1 reactor were completely exposed to the air and rapidly heating five hours after the quake.' Apparently, the earthquake had caused a crack in the containment vessel. Which means, that even without the generators failing, the meltdown might still have happened. With this new data, it seems a similar incident could happen in an earthquake zone even without a tsunami."

Comments

Uh... summary?

[zalas]

Article:
The operator of the crippled Fukushima Daiichi nuclear plant said it is studying whether the facility's reactors were damaged in the March 11 earthquake even before the massive tsunami that followed cut off power and sent the reactors into crisis.
Kyodo news agency quoted an unnamed source at the utility on Sunday as saying that the No. 1 reactor might have suffered structural damage in the earthquake that caused a release of radiation separate from the tsunami.
Summary:
Apparently, the earthquake had caused a crack in the containment vessel.

I'm not sure how the summary writer came to that conclusion... Shouldn't we wait for an actual report/finding before stating that?

Re:Uh... summary?

[Kilrah_il]

You should be modded -1 Factual or -1 On-topic :)

Re:Uh... summary?

[he-sk]

Here's a better writeup:

Mainichi Daily News: http://mdn.mainichi.jp/mdnnews/news/20110517p2a00m0na008000c.html
taz (German): http://taz.de/1/zukunft/umwelt/artikel/1/tepcos-verteidigung-broeckelt/

According to these articles, reactor no. 1 experienced some kind of problem (sudden drop of pressure) 10 minutes after the earthquake and well before the tsunami struck. The crew then had some troubles with the cooling system of said reactor but the articles are pretty vague in that regard. This is according to TEPCO's own reports.

Anyway, I've always maintained that the assertion that the earthquake did no damage in Fukushima (and therefore other nuclear plants are "safe") was nothing but a myth pushed by nuclear apologists in their own self-interest. It's nice to see some factual reporting backing up my thesis, by the nuke operator no less.

Re:Uh... summary?

[ozmanjusri]

[reactors...] breached containment. [citation needed]

'Engineers from the Tokyo Electric Power company (Tepco) entered the No.1 reactor at the end of last week for the first time and saw the top five feet or so of the core’s 13ft-long fuel rods had been exposed to the air and melted down.
Previously, Tepco believed that the core of the reactor was submerged in enough water to keep it stable and that only 55 per cent of the core had been damaged.
Now the company is worried that the molten pool of radioactive fuel may have burned a hole through the bottom of the containment vessel, causing water to leak.
“We will have to revise our plans,” said Junichi Matsumoto, a spokesman for Tepco. “We cannot deny the possibility that a hole in the pressure vessel caused water to leak”.'

AFAIK, all the "leaking radioactive material" stories are about the spent fuel pond(s) not the reactor cores.

Leaking?

"United States government engineers sent to help with the crisis in Japan are warning that the troubled nuclear plant there is facing a wide array of fresh threats that could persist indefinitely, and that in some cases are expected to increase as a result of the very measures being taken to keep the plant stable, according to a confidential assessment prepared by the Nuclear Regulatory Commission."

"The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed."
http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?_r=2&hp

Re:Uh... summary?

[jafac]

Well, it was also fairly obvious given the following:
- Among the long history of safety procedure fraud at Fukushima, by TEPCO, were instances where repairs were performed using procedures that were not approved by standards, but signed off as otherwise. (therefore - plant infrastructure which may have been *designed* to withstand certain g acceleration forces of an earthquake in 1971, may not be able to withstand those forces 40 years later, after these un-approved, but fraudulently certified repairs.) - The article which mentions these variances does not provide specifics.

  - When Unit 1, and 3 exploded, the roofs of the building blew off. This indicates that the hydrogen had been generated in a reactor core at over 2200 degrees C, in the presence of water, and escaped the primary cooling system, venting into the reactor building's structure through the particle scrubbers, and exploded. A hydrogen explosion is not good, of course, but only indicative of a loss-of-cooling, at a minimum. Many experts will say that hydrogen generation is pretty much a sure sign of melting; it's not precise, but when you're in the ballpark, in a nuclear reactor, things can get very unstable very quickly, (like, milliseconds-quickly). None of these units had instrumentation, or controls, or active cooling going on. As hot byproducts are released - they have much lower melting points than the Uranium fuel, and they can migrate around, and collect in different states (or chemically react with eachother, and have a completely different set of properties - and these properties could be caustic, or explosive) . . . and cause hotspots, regions of high flux. (while some byproducts absorb neutrons and slow the reaction down). Pretty much all bets are off, as far as predicting what's going to happen.

Strictly speaking, hydrogen generation does not mean melting HAD to happen. But in this situation, it was highly improbable that melting wasn't happening in conjunction with that.
(and the hydrogen generation did not necessarily happen at the time of the explosions - the explosions happened later).

  - When Unit 2 exploded, the explosion blew out the side of the base of the building, through the condenser, in the primary cooling. This means that the hydrogen collected and ignited in the primary cooling system. This also means that there was enough heat in the condenser to provide ignition. This could have been due to excessive steam pressure, (compression-ignition) - with oxygen leaking IN through structural cracks. It strongly suggests that Unit 2 was damaged structurally, (the concrete torus), in the quake. It could be that thermally hot byproducts or corium caused the ignition in the RPV, maybe with an oxygen isotope (I don't know if this is possible or not, probably not), or dissasociated water,(weird isotope chemistry?) or the ignition source made it's way into the torus (which would mean, holey RPV+holey primary cooling = open core). I can't really say what the ignition source could have been, but the presence of oxygen is the crazy bit, and the simplest explanation is structural issues in the concrete (or connecting cooling pipes/valves).

I think it was pretty idiotic and foolish (okay. . . unprofessional?) for TEPCO to state, in the immediate aftermath of the first hydrogen explosion, that they knew that the RPV was intact. They couldn't get instrument readings, or even a visual inspection for many days after that explosion to even get a half-assed confirmation of that statement. It was this kind of fumbling around and PR mismanagement that does the most damage to the industry's credibility. It would have been better for them to state what they definitely knew - what data they had, and the range of possibilities that it could have meant. That first hydrogen explosion was absolutely the time to press the panic button and evacuate residents.

Re:Uh... summary?

[Rei]

If the containment vessel isn't leaking, how is all of the highly-radioactive, plutonium-bearing water accumulating outside of the containment vessel?

Lots of very respected sources are reporting that there was damage to the containment vessel in reactors 1 through 3, quoting multiple figures in the government and TEPCO. I'm going to trust their ability to cross-check their reporting more than your "linked report" which is just a second-hand summary of news reported by one source, not some official document.

Misleading Title As Usual

[borrrden]

Nowhere in TFA does it say that the earthquake caused the damage to the reactor that led to it melting. Also, I doubt it is even possible for it to melt in the 40 - 50 minutes it took for the tsunami to arrive. It first has to evaporate or otherwise evacuate the water inside the reactor, and then heat up to about 2800 C to melt. What the article is saying is that the rods had melted much sooner than initially thought. The timeline changed, not the reason. They are also looking into possible complications that may have occurred in the initial hour (there is another report that the cooling systems were manually shut off after a pressure drop, as per the instructions for such a scenario), but nowhere does it suggest that the earthquake, and not the tsunami, caused the crisis. The closest it comes to that is saying that the earthquake may have "damaged" the reactor, but gives no speculation on the effect that it would have had on the cooling system. A crack in the containment vessel without any cracks in the reactor pressure vessel would not have been an issue.

Re:Misleading Title As Usual

[rrohbeck]

If there was a crack at the bottom of the RPV, the pressure would have pushed water out rather quickly.

Re:Misleading Title As Usual

[DrBoumBoum]

No, the batteries provide nowhere near the power required by the cooling system, this was explained on slashdot a few weeks ago by a guy working with the pumps (sorry no time to find the comment now). The cooling system consumes a large amount of the total electrical output of the plant (something between 10 and 20 percent, again from memory), no battery setup can provide this amount of energy. The batteries are only used to power the instrumentation and control mechanisms (valves etc).

Re:Misleading Title As Usual

[Fierlo]

Except that decay power is about 7% or so right after shutdown. I'm not entirely sure where you got the 10 MW thermal. Unit 1 is a 480 MWe reactor. If you generously assume a 50% efficiency (it wasn't)...

480/0.5*0.07 = 67.2 MW thermal

More likely it's in the mid 30s (or even low 30s) for efficiency, so you end up around 96 MW thermal immediately after shutdown.

Re:Misleading Title As Usual

[Mindcontrolled]

Yeah, that was a brainfart - I wanted to shoot for order of magnitude only, so I originally planned to set 10% of total thermal power. That somehow got garbled into 10 MW. So I undershot it by a factor of 10. You are right, with losing about 150 tons of water, the core would probably fall dry within the hour given a loss of circulation immediately after scram.

Battery Power

[mdsolar]

There is a detailed diary here: http://online.wsj.com/article/SB10001424052748703509104576330531564264132.html

"Documents released by Tepco Monday showed the isolation condenser— an emergency cooling system installed on Reactor No. 1 before the quake as a final resort in case of a total loss of power—worked only sporadically, if at all. Tepco officials explained that somebody appears to have manually closed the valves on the condenser soon after the March 11 quake—but before the tsunami hit about an hour later—to control the fluctuating pressure inside the reactor. Reopening the valves required battery power, so those valves likely couldn't be opened because the tsunami damaged the backup batteries.

If the valves hadn't been shut, things might have turned out differently. Temperatures in the reactor climbed faster than initially expected, causing more and faster damage. Tepco admitted this week the problems at Reactor 1 were far worse than originally thought. Its new projection shows fuel may have started melting rapidly only five hours after the March 11 quake. By 6:50 a.m. March 12, the fuel was likely in a heap at the bottom of the vessel. "

Battery power was lost apparently.

Re:No.

[Anonymous Coward]

Exactly. Nuclear energy is safe. Every accident that ever happened is just a unique occurrence that could NEVER happen in *insert country of residence*. And when it's going to happen anyway, it's the fault of anti-nuke activists because they wouldn't let us build new and improved reactors. We would have totally built those despite the massive profit margins we have with the old ones. Honest!

Cheap, Defective Containment Vessel

[Doc Ruby]

Mitsuhiko+Tanaka was an engineer who led Fukushima's building of the reactor vessel. He told Japan's government following Chernobyl's explosion that he had helped TEPCO cover up the fact that the reactor vessel was damaged during its manufacture. Japan's government ignored him and continued to relicense Fukushima for many years past either his warning or Fukushima's designed lifecycle.

This is the problem with nukes: the people in its industry and government cooperate to protect the corporate profits rather than the public even when those two interests are in conflict. Regardless of technical solutions to technical problems (which cost money and are ignored when the corporation can get away with it), the problem that's proven impossible to solve is the failure to properly regulate the rich essential monopolies owning or running the nuke plants.

Which is a problem not just where earthquakes and tsunamis are the particular risk. It's a problem in countries like Russia, Japan and the US.

That is the risk that nuke boosters never admit: the risk of human error in the regulation and oversight, not just the engineers. These nukes are too risky for our corruptible industrialists and government people to be trusted with.

"There's no difference between theory and practice - in theory. In practice, there is a difference." - Yogi Berra (paraphrase)

Re:Cheap, Defective Containment Vessel

[antifoidulus]

Unfortunately this isn't an isolated incident in Japan and really the only question was when, not if, something like this would happen. It's a pretty open secret that government has been in bed with TEPCO and the like for quite some time now, and that most "inspections" were mostly rubber stamp affairs. Hell, as recently as summer of 2003 there was a shutdown of a large number of reactors in the Tohoku region because it was found that managers were intentionally papering over gross safety violations. You would have thought that would have spurred the public into action, but it really did nothing.

You also have cultural issues at play. People like to point out how there was virtually no looting after the tsunami, and rightly so, but the downside of that same culture is a lack of whistle-blowing. Japan is still in many ways a Confucian society, and as such there is very little in the way of whistle blowing. And even when there is, people tend not to believe the whistle blower over his "superiors" at work because well, they are his superiors......

That being said, I would be willing to bet Japan goes from the rich country with the worst nuclear safety record to having one of the best. The Japanese throughout history have been a society that is very poor at initiating change, but the best at adapting to it, unfortunately it takes a huge shock for them to really change anything. Case in point, their air safety record. Japan used to have one of the worst air safety records around, but thanks to a string of major accidents in the 60s, and one huge accident(deadliest single airline crash in history) in the 80s, they now have probably the best air traffic safety records on the planet. There have been no passenger deaths in Japan since 1994, and there has only been one fatal incident involving a cargo jet. Considering the amount of air traffic both in Japan and from abroad, that is pretty damn impressive. Doubly so when you consider how small the airports are and how many flights they have to get in and out. The airline industry suffered from a lot of the same problems the nuclear industry does, rubber stamping, no whistle blowing etc. Hopefully this will serve as a wakeup call to the Japanese much in the way the major air accidents did.

Re:Cheap, Defective Containment Vessel

[radtea]

Yep, we can't trust our government or companies to do anything competently. For our own safety, we should clearly ban:

Nuclear plants are unique amongst these things in that their failure modes are:

1) rapid
2) complex
3) expensive

The speed comes from the energy density of the core, which is many orders of magnitude higher than for any other power source. A typical nuclear plant contains something like the equivalent of 100,000 boxcars of coal in its fuel rods, and while only a tiny fraction of that can be released over a reasonably short interval, only a tiny fraction has to be released over a relatively short interval to ruin the core.

Reactor kinetics are complicated and the cooling and control systems more-so. Complexity is a bigger issue in second and third generation designs--one could even say that the whole point of fourth generation designs is to engineer out as much complexity as possible. However, there is always going to be a fairly high level of complexity for anything beyond the "nuclear battery" type reactors (which to my mind are probably viable sources of energy in the long term.) The high energy density and consequent rapid pace of events during failure mean that the humans involved in the process are going to frequently make bad choices.

The cost is the big problem: a failure in a coal plant results in some nasty chemicals released into the environment, maybe some people burned in a steam explosion or the like. But it is very hard to create a coal plant disaster that writes off the capital investment or exposes the operator to the kind of widespread liability that nuclear disasters do.

So anyone who is not innumerate realizes that the risk-cost/benefit trade-off for nuclear power is very different from most other technologies. The benefits are significant, but a long, long way from "power too cheap to meter", which was the original promise of nuclear power. The costs are having an event like Windscale or Chernobyl or Fukushima every decade or two. For numerate people, the trade-offs involved are not a slam-dunk on either side.

Time for some slashdotters to eat crow

[Agent0013]

I wouldn't say that I am anti-nuclear, but I do think it can be dangerous. Especially with the corner cutting that a lot of corporations try to use to save money. I was struck by this news on how many times I saw a pro-nuclear slashdotter post how the power plant had survived the earthquake just fine. Many people were saying how it was an amazing triumph of engineering that it could withstand the quake that was ten times what it was designed for. If only they had put the pumps up on stilts or someplace where the tsunami would not have caused the damage, everything would have been just fine. I guess that was just a bunch of wishfull thinking now huh? Sure, I understand that at the time it had looked like it survived the earthquake without damage. But you end up losing some credibility and start to look like a fool when it turns out you were completely wrong because you didn't yet have all the facts.