What is the worst case scenario for Japan right now? (re: Nuclear plant)

This may have already been asked but I didn’t see a thread on it.

What is the worst thing that could happen with the Japanese nuclear plant, and what sort of devastation are we talking about?

The realistic worst-case scenario is a Three Mile Island type incident, where the core melts down within the containment vessel. The Fukushima reactor complex will be ruined and un-salvageable, with a lengthy and expensive cleanup process. Some radioactive gases will be released, which will cause no detectable harm to the environment or people living nearby, but will be blared in large headlines in the media and used by anti-nuclear activists to scare people.

In the longer term, Japan will be reluctant to build any more nuclear power plants, instead choosing oil or other fossil fuels. This will in turn cause far more environmental harm and illness than the Fukushima reactor’s meltdown did.

So me reading that it could wipe out Japan was rubbish and I was a fool to give that idea any measurable amount of thought and consideration?

Pretty much. A reactor meltdown of this type can’t cause more than localized damage.

The worst case is a full meltdown that would breach the bottom of the building. What exploded was the outer containment building which filled with hydrogen gas and exploded. The inner building containing the core is still intact.

A visual of what is going on.


No, Gamera.

No, wait, a battle between Mothra and Gamera.

The plant is probably already unsalvageable. Sea water is so corrosive that using it as coolant wrecks a reactor. Of the three reactors is the plant, one is already gone. With leaks reported at the other two, they possibly will be next. The nuclear industry uses a scale of 1-7 for problems, with Chernobyl a 7. This is currently a 4.

The plant may reopen, and it might close permanently. That is the realistic worst-case scenario at this point, unless things have changed drastically in the last hour.

Breaching the containment dome by overheated melting rods is a horrible environmental disaster that could have vast reach, with the details totally unpredictable ahead of time. You need to distinguish that kind of meltdown from the term that is wrongly being used in the press now. Fuel rods within the reactor may have melted from the heat, so that is a “meltdown” of sorts, but as long as they stay within containment they have no more effect melted than they do as working reactor rods. Wiping out Japan is unimaginably silly. Two atomic bombs didn’t wipe out Japan. And a nuclear plant cannot explode in such a fashion.

I thought that was a best-case scenario.

the assumption is that the control rods reset to their shut-off position which takes days to cool down. If the rods are out of place then that makes things worse.

What are your thoughts on this one? I have no idea but it certainly scares me more than the reactor meltdowns. I’ve now read quite a bit on meltdown stuff but there doesn’t seem to be much mention of the pools.

“In addition to the reactor cores, the storage pool for highly radioactive irradiated nuclear fuel is also at risk. The pool cooling water must be continuously circulated. Without circulation, the still thermally hot irradiated nuclear fuel in the storage pools will begin to boil off the cooling water. Within a day or two, the pool’s water could completely boil away. Without cooling water, the irradiated nuclear fuel could spontaneously combust in an exothermic reaction. Since the storage pools are not located within containment, a catastrophic radioactivity release to the environment could occur. Up to 100 percent of the volatile radioactive Cesium-137 content of the pools could go up in flames and smoke, to blow downwind over large distances. Given the large quantity of irradiated nuclear fuel in the pool, the radioactivity release could be worse than the Chernobyl nuclear reactor catastrophe of 25 years ago.”

Can you give us a source for this? You put it in quotes but without attribution. At first sight looks like scaremongering.

To keep a sense of proportion, it now looks as though the death toll for this disaster will be 10000+. Even if this report was accurate and the worst happened, deaths due the the nuclear accident will be dwarfed by those caused by the initial quake and tsunami.

Where is Una Persson when we need her?

This stuff is custom built for her expertise.

I’d love to hear her take on this stuff.

(maybe she is busy fixing Japan…seems plausible and reasonable for her absence here :wink: ).

It’s from this page http://wallstcheatsheet.com/breaking-news/economy/explosion-at-japan-nuclear-plant-updates-and-video.html

Ah! I see it:

Not exactly an unbiased source but I did some googling and it is a real hazard. See thisNuclear Regualtory Commission report and thischapter from a Board on Radioactive Waste Management report. As I read it, definitely not good but a lot easier to deal with than the problems with the actual core as it takes days to happen and all it needs is to top up the water level with a fire hose to prevent it.

Huh. Funny. Back in the '80’s there was a sci-fi book that detailed precisely that – Japan being mostly destroyed in an earthquake, resulting in mass emigration, and a boost to technological advancement world-wide from the knowledge importation. The author of your new story must have read that old sci-fi.

Here is a link to the NEI which has been providing periodic updates the last few days: http://www.nei.org/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region

From the lastest update on Fukushima Daiichi where things are the worst:

Fukushima Nuclear Accident – a simple and accurate explanation.

Can we stop the scaremongering?

The long term effect is that it will destroy the earth’s climate. Not from the accident itself, but because the anti-nuclear panic will mean we will rely more on fossil fuels.

That article was pretty rah-rah about the safety of the plant. Personally, I doubt anything too serious will happen, but as an engineer with 30 years of experience, I’ve seen enough systems fail in weird and wonderful ways to make me a little leery about people claiming that “there’s no need to panic.”

Flying turtles and moths are cute but hardly worst case scenario material.

At any moment, Mechagodzilla may stomp on Tokyo.