Catastrophe in Japan: Radiation Risks Explained

The tragedy in Japan resulting from the earthquake and tsunami is difficult to comprehend. It is compounded by the damage to the nuclear power plant, resulting in radiation releases with uncertainty as to how much more radiation will be emitted.

An area in the vicinity of the nuclear plant, extending outwards for tens of miles, will require decontamination before it is safe for human activities. However, the further distance one gets from the nuclear plant, the less concentrated the contamination level. The danger from any radioactive material released by the plant is from ingestion, either by breathing in dust particles, drinking contaminated water, or by eating food that has concentrated the radiation. Without too much difficulty, it is possible to prevent such ingestion from occurring. External radiation exposure is of concern only for the workers who are in the immediate vicinity of the reactors or fuel rods, where the overwhelming amount of radioactivity is located and will remain – even in the event of a “meltdown” of the containment vessels that surround the reactors.

There has been considerable publicity about radioactivity from the Japanese nuclear power plant reaching the United States and what impact it might have on the U.S. population (and in particular the residents of California and other West Coast states).  Simply stated, there has been no impact and there is unlikely to be any impact even in the event the releases from the Japanese plant become far more severe. The reason is that any radioactivity reaching U.S. shores will be greatly diluted. While instruments are available that can measure minute levels of radioactivity and these can detect radioactive emissions originating in Japan, the amount of radioactivity is very small. Merely detecting gamma rays does not mean levels are dangerous.

The radioactivity releases from the Japanese nuclear plant have been in steam releases and in the smoke from the fires that have burned. While some explosions have occurred, these are small in comparison to the size of an explosion that would be needed to spew significant amounts of radiation to high levels in the atmosphere where it could travel further at higher concentration levels. There is no danger of a nuclear bomb-type of explosion, which cannot occur with the nuclear fuel and conditions at the Japanese facility.

Theoretically, the worst-case scenario would be that molten globs of nuclear fuel, enriched uranium, could accumulate sufficiently that some fissioning could occur – resulting in the production of additional volatile radioactivity (primarily radioactive iodine and cesium) and a potential increase in the amount of radioactive emission from the plant. Fissioning is the process by which the uranium atoms split, producing the heat energy that the nuclear plants use to create steam for generating electricity. The likelihood of such an event is remote, even impossible, and it would not produce dangerous levels of radioactivity in the U.S.