Japanese reactor crisis

[Andrew, Jr.]

I have been watching the news on Japan. I am not understanding what is going to happen to the outter core if it totally comes down or falls apart. It is already damaged.

I am thinking about the long term effects of radiation on people and animals. Harmful just isn't answering my question. The ripple effect of this crisis is going to last generations if you ask me.

[dreadgeek]

Japan Earthquake Update (15 March 2011, 20:35 UTC)
The Japanese government today requested assistance from the IAEA in the areas of environmental monitoring and the effects of radiation on human health, asking for IAEA teams of experts to be sent to Japan to assist local experts. Preparations for these missions are currently under way.

The missions will draw on IAEA resources and may also possibly involve Response and Assistance Network (RANET) and Member States' capabilities.

This development follows the IAEA's offer to Japan of its "Good Offices" - i.e. making available the Agency's direct support and coordination of international assistance.

RANET is a network of resources made available by IAEA Member States that can be offered in the event of a radiation incident or emergency. Coordination of RANET is done by the IAEA within the framework of the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

http://www.iaea.org/newscenter/news/...iupdate01.html

[dreadgeek]

Originally Posted by Andrew, Jr.

I have been watching the news on Japan. I am not understanding what is going to happen to the outter core if it totally comes down or falls apart. It is already damaged.

I am thinking about the long term effects of radiation on people and animals. Harmful just isn't answering my question. The ripple effect of this crisis is going to last generations if you ask me.

Andrew:

I will do my best to explain to the limit of my own understanding.

IF the worst of all possible scenarios were to happen and one or more reactors experienced a catastrophic meltdown of the entire pile and IF it then melted through the primary containment vessel AND the outer containment vessel and IF it then melted into the earth and had enough energy to keep melting material until it reached the water table THEN there could be an explosive release of steam and what would then be highly radioactive dirt into the environment. But notice that there are a lot of conditionals before it gets there. A lot of things would have to go wrong for things to get that bad.

However, that is vanishingly unlikely while still having a probability that is larger than 0 (where 0 means that there's no chance of it happening and 1 means that it is certain to happen).

As I understand it, right now NONE of the reactors are undergoing active fission. This is good. That means that all they have to do is keep pumping water into the cores, keeping them submerged, until such time as the decay heat reaches a manageable level. Think about the inside of the core like you would either fireworks (the kind you buy from the Boy Scouts) or a hot pan. When I was a kid and we would do fireworks on the 4th of July, my job was to fill up a bucket or washtub with water. My dad would light the fireworks, they'd burn, we'd dunk them in water and the next day pour the water out and then dispose of the fireworks. So the reactor is the firework, the sea water represents the bucket of water. Even after the fuel rods are pulled from the core (meaning they are no longer undergoing fission) there is residual heat--this is called the decay heat. That's why the cores have to be covered by water until the rods and the core cool down.

The fires (and as I was writing this another fire broke out) are actually happening in a storage area for spent fuel rods. The problem is that the area around this pool is now too hot (radioactively, not thermally) for workers to approach to put water in to fill the pools to keep the spent fuel rods (which are in cases) from becoming uncovered. This is where I wish we had more sophisticated robotics.


Cheers
Aj

[Martina]

i read they were considering using heliocopters to drop water into the pool.

[dreadgeek]

Originally Posted by Martina

i read they were considering using heliocopters to drop water into the pool.

I'd read that but now I'm hearing they are rethinking that.

Cheers
Aj

[AtLast]

Originally Posted by dreadgeek

Andrew:

I will do my best to explain to the limit of my own understanding.

IF the worst of all possible scenarios were to happen and one or more reactors experienced a catastrophic meltdown of the entire pile and IF it then melted through the primary containment vessel AND the outer containment vessel and IF it then melted into the earth and had enough energy to keep melting material until it reached the water table THEN there could be an explosive release of steam and what would then be highly radioactive dirt into the environment. But notice that there are a lot of conditionals before it gets there. A lot of things would have to go wrong for things to get that bad.

However, that is vanishingly unlikely while still having a probability that is larger than 0 (where 0 means that there's no chance of it happening and 1 means that it is certain to happen).

As I understand it, right now NONE of the reactors are undergoing active fission. This is good. That means that all they have to do is keep pumping water into the cores, keeping them submerged, until such time as the decay heat reaches a manageable level. Think about the inside of the core like you would either fireworks (the kind you buy from the Boy Scouts) or a hot pan. When I was a kid and we would do fireworks on the 4th of July, my job was to fill up a bucket or washtub with water. My dad would light the fireworks, they'd burn, we'd dunk them in water and the next day pour the water out and then dispose of the fireworks. So the reactor is the firework, the sea water represents the bucket of water. Even after the fuel rods are pulled from the core (meaning they are no longer undergoing fission) there is residual heat--this is called the decay heat. That's why the cores have to be covered by water until the rods and the core cool down.

The fires (and as I was writing this another fire broke out) are actually happening in a storage area for spent fuel rods. The problem is that the area around this pool is now too hot (radioactively, not thermally) for workers to approach to put water in to fill the pools to keep the spent fuel rods (which are in cases) from becoming uncovered. This is where I wish we had more sophisticated robotics.


Cheers
Aj

Yes, I have to say that I was quite intrigued with the robotic capabilities used to deal with the Gulf deep water oil spill. Amazing, but a very different set of variable.

[Andrew, Jr.]

AJ,

Thank you for explaining this to me. I greatly appreciate it.

I am on information overload with the constant news. I am taking time off tomorrow to give myself a break. Tonight on ABC News with Diane Sawyer I saw a dead dog, and then she showed the devistation all over Japan from different perspectives. It is really the same destruction. So much suffering.

[Miss Scarlett]

From NPR:

Fukushima, Three Mile Island, Chernobyl: Putting It All In Perspective
by NPR Staff

The situation at Japan's Fukushima Daiichi facility is prompting many comparisons to the two prior crises that have become cultural touchstones for what can go wrong at a nuclear power plant: Three Mile Island and Chernobyl.

See how the disasters compare.

Three Mile Island
Date: March 28, 1979
Place: Near Harrisburg, Pa.

Problem -A failure involving the water pumps allowed pressure to build up inside the reactor core; in response, a relief valve automatically opened. But it failed to close again — and cooling water escaped the reactor. Meanwhile, operators at the plant didn't get the signal that the valve was still open.

What Happened To The Core -The nuclear fuel rods inside the reactor experienced a partial meltdown — meaning some of them overheated and melted. However, the radioactive material never escaped the containment vessel.

Exposure-Experts say the resulting radiation exposure was never enough to cause a detectable health effect in the general population.


Chernobyl
Date: April 26, 1986
Place: About 80 miles north of Kiev, Ukraine

Problem - Operators were performing a test to see how the reactor would fare in case of electrical failure, when a design flaw in the reactor caused a dramatic power surge.

What Happened To The Core - The core hadn’t been shut down prior to the test. The power surge triggered events that sent the nuclear reaction out of control — causing two explosions. The reactor was not surrounded by a containment structure, so the explosions and the subsequent fire sent a giant plume of radioactive material into the atmosphere and was spread out by the winds.

Exposure -At least 5 percent of the radioactive reactor core was released into the atmosphere. Two Chernobyl plant workers died on the night of the accident, and 28 more people died within a few weeks from radiation poisoning. Long term, several thousand more people were put at risk for cancer.


Fukushima Daiichi
Date: March 11
Place: Fukushima prefecture, about 150 miles north of Tokyo on Japan's northeastern coast

Problem - Emergency cooling systems at the plant started to fail after a massive quake and tsunami knocked out electricity at the facility. Workers have experienced numerous problems maintaining water levels in the three reactors that were in operation when the quake struck. Water is needed to keep the nuclear fuel rods inside the core from overheating. Officials suspect rods have melted in multiple reactors.

What Happened To The Core - So far, four of the six nuclear reactors are in trouble. In Unit Nos. 1 and 3, explosions occurred from a buildup of hydrogen gas. These were not nuclear blasts. Experts suspect the nuclear rods inside these two reactors have started to melt but have not breached the containment vessel, which is designed to keep radioactive material from escaping.

Unit No. 2 poses a bigger threat: An explosion may have caused a breach in the containment vessel, which may allow radioactive steam or water to escape

Unit No. 4, which had been closed down for maintenance before the quake hit, caught on fire. The fire occurred near a pond where spent fuel rods were left to cool off. Officials believe the fire caused a radiation leak near the pool. The challenge is keeping the rods — which are still hot — covered in water so that they don’t overheat and release more radioactive material.

Exposure - Not yet known.

Source: USNRC, World Nuclear Association

http://www.npr.org/2011/03/15/134568...in-perspective

[Medusa]

There's just been a report that the last 50 workers have been released

Which means that nobody is manning the reactors.

Which means they've given up

I hope like hell that is just a bad translation. They are clarifying now.

[Medusa]

Oh shit.

http://www.washingtonpost.com/world/...joa_story.html

[Rockinonahigh]

I know very little about reactors,ive read some post but im a simple minded person who just deals with life as it comes.I just hope that when all this is over ...whenever its over,we all learn a lesson on how to protect ourselves and the world we live on from these things when they happen.My heart goes out to all off the people of Japan as well as many others who will be effected by these circumstances.Who ever our highr power may be,may he or she look upon us with benevolent eyes.

[dreadgeek]

Originally Posted by Medusa

There's just been a report that the last 50 workers have been released

Which means that nobody is manning the reactors.

Which means they've given up

I hope like hell that is just a bad translation. They are clarifying now.

Actually it appears that they were off-site for 45 minutes. There was a spike in radiation, they do not know why it spiked. I'm trying to get the latest update from the IAEA but right now, their traffic is so high that I can't get the page to load!

I will update as I get more information.

Cheers
Aj