Dear Science

This week, Science answers more questions about the Japanese nuclear reactor crisis.

What kinds of radiation are leaking out of the damaged reactors?

Three different kinds of radiation are now leaking from the reactor complex. First are forms of radiation generated when atoms spontaneously fall apart: high-energy electromagnetic waves (like gamma and X-rays), alpha and beta particles. The strength of radioactive waves like these decreases at an exponential rate—incredibly quickly. For the people who are working in the plant right now, these are the primary concern; unless you’re in Japan, within miles of the plant, you won’t ever be exposed to these.

Second, there are reports that the plant has been, intermittently, releasing high-energy neutrons. Neutrons—along with protons and electrons—are the parts that make up the inside of an atom. When nuclear fission occurs, neutrons are flung out of the shattering atoms at high speeds. Therefore, neutrons like these can be detected when a nuclear fission chain reaction is occurring. Within seconds after the earthquake was detected, the nuclear chain reactions in the reactors were shut down. The fact that this form of radiation is still being detected beside the plant implies—worrisomely—that there is some nuclear fission still going on somewhere in the reactor complex that is not yet controlled.

Third, the plant is leaking radioactive elements. These elements are created by the breakdown of atoms in nuclear fission. Most of these are short-lived and only a problem for people working at the (now destroyed) reactor. The most dangerous of these elements is iodine 131—a radioactive version of iodine that can become part of foods. When people eat foods contaminated with radioactive iodine leaking from the plant, this iodine becomes part of the thyroid gland in their neck. After the Chernobyl accident, children who ate foods contaminated with radioactive iodine had a much higher chance than normal of getting thyroid cancer later in life.

Are we safe in Seattle? Can any of this leaking radiation cause health problems for kids here?

Neither the neutrons nor the electromagnetic waves (including the gamma radiation) have any chance of reaching Seattle. In contrast, some of the radioactive elements leaking from Fukushima have already reached Seattle—in tiny amounts, barely detectible by the most sensitive equipment—blown here by the wind. The most dangerous of the elements (radioactive iodine) is short-lived, existing for only about 40 days after the reactors are shut down. A lot of it has been washed into the north Pacific Ocean, near the power plants; fortunately, the Pacific Ocean is huge. The odds of food you’d eat here in Seattle being contaminated with radioactivity from Japan is too small to worry about. The cheap eggs in your fridge (from a factory farm/resistant-bacteria-breeding-ground) are a bigger threat to a kid.

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dearscience@thestranger.com.