The Japanese have been trying to stabilize the Fukushima Daiichi plant by injecting first sea water, then fresh water, and most recently paper and sawdust. The fuel rods continue to superheat and may have turned partially molten. The Japanese have underestimated the severity of the disaster and overestimated their ability to handle it. According to the New York Time, "Among other problems, the document raises new questions about whether pouring water on nuclear fuel in the absence of functioning cooling systems can be sustained indefinitely."
The Daiichi plant went critical when the earthquake/tsunami combination shutdown the power grid. Without power to operate the cooling pumps in the reactor, the fuel rods quickly burned of the coolant in the system. Because the Daiichi plant in on the coast, water was the logical solution as it was in abundant supply. Unfortunately, the use of water has significantly degraded the structural integrity of the containment vessel. It will take months to stabilize the plant to enough to effect repairs but continuing to pour water into it presents two problems. One, as previously stated injecting water may accelerate damage to the reactor. Second, all of the water being injected becomes radioactive and presents the problem of disposal. Reports show that the water around the plant contains over 7 million times the legal limit of radiation.
The Russians had perhaps the best idea; entomb the reactor in concrete and boron. The Japanese desire to maintain face may have prevented them from accepting this option which would have meant the situation was beyond their ability to control.
If the plant continues to be cooled by water injection, it raises the risk of additional explosions that can spread radioactivity in the air. Reports are increasing that blue neutron beams can be seen from the nuclear fuel. Daiichi is not just a Japanese problem. The insurance rates are skyrocketing and food prices will soar even higher (prices were already rising due to the Libyan no-fly zone).
All of this causes me to agree with Brother Farrakhan, with whom I normally don't, when he criticized President Obama for not taking charge here in the US. What is the US doing about the potential of radiation exposure? What happens if Japanese goods start showing up with radiation? If there are explosions and radiation becomes airborne, what will the US do to prepare citizens?