I wanted to give you a really good explanation of what is going on with the Japan nuclear reactors. If you are like me (a layman on issues of nuclear energy and what actually goes on) you'll find this explanation really helpful.
It is from a friend of mine who works in that industry. I asked him if I could post it and he said yes.
And please pray for the people of Japan in this time of disaster and crisis.
In case you are wondering what my take is on the nuclear crisis I have tried to capture what I believe the situation is in the following letter. But please understand I am not an expert I just know enough to be dangerous. AND this isn't intended to be a press release, just the opinion of someone who, for nearly 30 years, has worked at a nuclear plant similar to the one's that are in trouble in Japan.
However, they are in a very, very bad situation over there. I obviously don't know exactly what is going on, and what they are planning, but just hearing that the spent fuel pool at the one reactor has no water in it, is a huge deal. The spent fuel pool is where the old fuel is stored after it is taken out of the reactor. The spent fuel gives off a hellacious dose rate. The water acts as a shield, actually water is very affective as a shield.
So when there is no water in the pool the super high dose rate given off makes the pool, and really the surrounding area, unapproachable. With out any shielding, like vertically above the pools, I'm talking within 100's of yards, can be deadly. That's why the helicopters had to stop flying and attempting to dump water. Horizontally it wouldn't be as bad due to the thick cement walls. Non-the-less the plants are virtually uninhabitable.
And the issues of cooling the fuel pool is still a major problem - at least at the one plant. The decay heat given off by even spent (used) fuel has to be dealt with. And since they didn't have any way to cool the water the water evaporated (boiled)out of the pool. And they still are having issues with cooling the reactors, which is the major concern, though the fuel pool situation is dire.
It helps if you understand several things when you hear them talk about radiation on TV:
1) When they say the radiation levels have increased 100 times it is a relative term. Generally the ambient radiation levels are so low that even at 100 times normal radiation levels the dose rate might only be 1 or 2 mR/hr which is not an appreciable health risk.
2) The high dose rates coming off of the fuel is a very local issue (plant site, and surrounding neighborhood).
3) Airborne contamination is caused by very small radioactive particles that can be in dust or ash as in the case of Chernobyl, which was much worse as far as an environmental disaster due to the fire which created a radioactive smoke carrying the contamination up into the atmosphere. Airborne contamination is a concern because the particles can be ingested into your body by breathing or eating contaminated food which can cause latent affects (affects years later).
4) And gases such as Iodine, Krypton, Xenon. These gases are formed in the fission process in the reactor. The airborne contamination and gases, when released from a plant, form what is called a plume. The plume is of concern to those down wind of the release. This can be a big issue depending on the concentration and mixture (what specific isotopes are actually in the plume) of radionuclides. The plume will be so diluted when it even gets to Hawaii that it won't be an issue. The fact is every running nuclear plant in the world is, by necessary design, releasing low levels of radioactive iodine and other radionuclides every second, much like your car, by necessary design, gives off carbon monoxide. What is released is regulated and monitored very, very closely and reported to the NRC. We (Peach Bottom) release less than 1%, in any given time period, of what we are legally allowed to.
Iodine Tablets: I'm sure most of you know that the iodine tablets are something that should only be taken when instructed by a doctor or the state. The are not a "anti-radiation pill" they only saturate your thyroid with "clean" iodine to prevent radioactive iodine from concentrating there. The side affects from taking the tablets are not pleasant and can be dangerous.
As far as the Japanese plants go - I really don't know what they are going to do. It's very bad. Understand that the events leading to this were so unimaginable it is a true testimony to the engineering that it isn't much much worse. The plants that are affected are the same genre as Peach Bottom, in fact they were designed by the same company (GE) and under construction at the same time. I think they are very similar.
And I can honestly tell you that even though we live close to Peach Bottom I am not concerned for my or my families safety at all. The tsunami was the killer. Even though the earth quake was much worse than the design base (what they anticipate could possibly happen and design for) it did little damage other than knocking out their off-site power supply, which is bad because that is what powers the plant and the vital equipment,
BUT that is taken into account when the plants are built and every plant has large diesel generators (Emergency Diesels) that come on in seconds (<10 seconds) and pick up the power load - which they did. However, the tsunami was also much worse than they anticipated. It is my understanding that they had designed contignecies for a ~ 25ft high tsinomi, but, as we know, the wave was ~ 30 ft high and when the wave hit it took out the fuel tanks for the diesel generators, and so they lost their back up power supply, at that point it was a nightmare. Bottom line is you have got to be able to move water to run a steam plant, especially a nuclear plant, just for the cooling if for nothing else, and without electric and pumping capability it's virtually impossible. It will be a huge victory when they get power restored with the emergency electric line they are trying to get operable.
Let me close by saying that the people who design and operate these plants are incredably smart and resourseful - I know because I see it first hand. They have an international team of the best of the best working to correct the situation and I have every confidence that, in a short time, it will be stabalized and recovery will be underway.