Fukushima 4 Spent Fuel Pool in Critical Condition

Nuclear workers who inspected the area in the Fukushima 4 reactor building under the spent fuel for the first time since the M9.0 earthquake and tsunami were met by a scene of destruction. TEPCO's plans to cool the spent fuel pool using existing plumbing will have to be scrapped. The plumbing that would have been used to cool the spent fuel pool is broken, bent and twisted beyond repair. The water in the spent fuel pool is close to boiling. TEPCO has been unable to cool the spent fuel pool below a temperature NHK reports as "above 80 degrees Celsius."

Because reactor 4 was being refueled when the earthquake struck in March, the spent fuel pool contains an exceptional amount of nuclear material. All the fuel from the reactor, plus a large inventory of old spent fuel is contained in the spent fuel pool that looms above the reactor vessel at the 4th story of the building that contains the reactor. TEPCO is working hard to prevent a loss of coolant accident that could lead to a spent fuel fire or hydrogen explosion which could spread radioactivity to the environment.

Because the spent fuel pool was designed for ease of refueling the reactor, not spent fuel storage, it is located high in the reactor building. Expert nuclear engineers have been flummoxed about how to deal with the situation at unit 4. Because the spent fuel is highly radioactive and densely packed workers cannot service the pool without risking high radiation exposure. It is hard to get heavy equipment high into the reactor building to get the spent fuel out the pool. And it is hard to keep the pool cool.

Moreover, the continued high levels of I-131, with a half life of just 8 days, near unit 4 could indicate criticality events might have taken place in the spent fuel pool since the earthquake. Because we don't know how the radioactive water got to where it is this is just a possibility. However, the ratios of Iodine-131 to Cesium-137 should be dropping rapidly because Cesium-137 has a much longer half life of 30 years. The continued high levels of Iodine-131 at several sites near units 2, 3 and 4 indicates that something is happening but we don't know what it is.

http://www.dailykos.com/story/2011/06/12/984424/-Fukushima-4-Spent-Fuel-Pool-in-Critical-Condition

hmmm support beams inadequate for strong aftershocks.

We were told there was nothing to worry about and stop posting alarmist BS

nevermind

Japan is contaminated with radioactive isotopes and their locally-grown food is, too. It's a terrible situation for them.

Let's hope they focus on remaking their energy grid in a renewable and sustainable way in the future. It's easy to say, though, and takes lots of money (which they don't have) and political will over generations to make it happen. Right now, Japan is using fossil fuels to take up the slack, which is not good, either.

Wiki: Radioactive Waste

The back end of the nuclear fuel cycle, mostly spent fuel rods, contains fission products that emit beta and gamma radiation, and actinides that emit alpha particles, such as uranium-234, neptunium-237, plutonium-238 and americium-241, and even sometimes some neutron emitters such as californium (Cf). These isotopes are formed in nuclear reactors.

It is important to distinguish the processing of uranium to make fuel from the reprocessing of used fuel. Used fuel contains the highly radioactive products of fission (see high level waste below). Many of these are neutron absorbers, called neutron poisons in this context. These eventually build up to a level where they absorb so many neutrons that the chain reaction stops, even with the control rods completely removed. At that point the fuel has to be replaced in the reactor with fresh fuel, even though there is still a substantial quantity of uranium-235 and plutonium present.

1) Melted-down Reactor 1
2) Melted-down Reactor 2
3) Melted-down Reactor 3
4) "Spent" fuel pool for Reactor 4
5) ALL OF THE ABOVE