Patrick J. Kiger at National Geographic News has an excellent summary of the current situation at Fukushima Daiichi Nuclear Power Plant. The plant continues to leak radioactive material into the sea, though at a rate much lower than the massive release that happened at the time of the accident. Strontium-90 (Half-life 28.79 years) has increased in proportion over various Cesium isotopes. This is a concern because while Cesium has the potential to enter the food supply in fish that pick it up, Strontium enters the food supply in a different way. In theory Cesium enters tissues and leaves tissues, and doesn’t accumulate over time. (I quickly add that there is evidence of Cesium accumulation in the fish food chain, so that may not be entirely true; certainly, tough, Cesium does not accumulate in large amounts). Strontium, on the other hand, substitutes for minerals in bone, and thus accumulated as a fish ages. Taking fish from contaminated waters for human consumption has mostly been banned since the accident (there are a few species of marine organism that have stopped showing detectable levels of radioactive isotopes, so they are now being caught).
The overall expected health risks of the Fukushima disaster overall and continued health risks because of the ongoing leakage are hard to estimate. There is almost certainly an elevated cancer risk for people living in the area, though the extent of this is unknown. Concerns that we see around the Internet that dangerous levels of radiation are reaching the US are incorrect.
Having said that, I think people often evaluate the significance of the Fukushima disaster incorrectly, for political reasons. Those who want to claim that nuclear power (including existing old-generation nuclear plants) is just honkey-dory seem to do so by feeding off of anti-nuke misconceptions and irrational fears about radiation. Yes, people do get it wrong; the average person has no clue what risks radioactive materials or radiation pose. For this reason, it is easy to creates straw men and then disprove them. The fact that the region around Fukushima is not littered with skeletons of people who were zapped into oblivion by the Fukushima multiple meltdowns, or that all babies in Japan are born with only one head and ten fingers, does not mean that nothing happened there. The fact is that you can’t go near this power plant without taking a serious health risk, and there is a moderate but real health risk because of the prior large scale dispersal of radioactive material and the ongoing lower level but still important outpouring (literally) of radioisotopes.
If we were to propose the construction of 22 nuclear power plants and noted that over a 30 year period one of them would suffer multiple meltdowns, spew enormous amounts of nuclear icky stuff into the air and sea, continued to spread contaminated water into the sea and groundwater for years after at a lower rate, create a very expensive problem that would last for decades and create a deadly no-entry zone filled with millions and millions of gallons of radioactive water and piles of nuclear material in the disabled reactors and spent fuel pools that could not be cleaned up for decades in a zone susceptible to serious earthquakes and tsunamis … the designers of that system might well be asked to go back to the drawing board or seek other alternatives. (Japan has about 22 plants operated over about 30 years, give or take.)
In fact, they were. They were asked to not do what they did, but those who opposed nuclear plants in Japan. The specific reasoning of the anti-nuclear activists and others may have included faulty logic and bad information about nuclear power, but on the list of potential problems was the possibility that what actually happened would happen. They were right. And they were not “stopped clock” right. They were right because they saw a real danger that really existed.
We probably have to build new nuclear power plants. Burning fossil fuels at the rate we are burning them will cause disasters that will make us forget bout our nuclear woes. But it is not true that the nuclear power industry is ready to step in and build significantly safer plants now, and it is not true that “alternative” (a term we should stop using!) energy solutions such as geothermal, solar, wind, and so on deployed on a smart grid with significant enhancements of efficiency at both production and use ends of the grid comprises a secondary solution.
Anyway, I gave only a short summary of what Kiger outlines in his excellent piece. Go now and read: Fukushima’s Radioactive Water Leak: What You Should Know