Locking up radioactive iodine

Researchers at the University of Sheffield in England report on a way to trap radioactive iodine and keep it from moving around and wreaking havoc.

After the earthquake and tsunami destroyed Japan's Fukushima nuclear power station, many rumors spread advising people to buy iodine tablets and swab their necks with iodine solution.

Radioactive iodine is dangerous because it spreads quickly, is easily absorbed by the body, and can cause cancer. It is especially dangerous for children, where ingestion of iodine-131 can result in thyroid cancer after 10 years or more.

Iodine 131 has been emitted by the Fukushima power plant as a gas since March 11. Although officials report that radioactive iodine levels that are constantly being monitored are well beyond the allowable limts, it is still a matter of concern that on May 28 there were reports that fish in Hong Kong were found to have the radioactive isotope. Some grey mullet from a wholesale market in Hong Kong had 7.7 becquerels per kilogram. The government guideline was is 100 becquerels per kilogram. Now it has been raised to 250 becquerels per kilogram. Officials were quoted by the report as saying "Based on risk assessment, normal consumption of grey mullets at this low radiation level will not pose any health risk to the consumer."

But for workers involved in rehabilitation work at the plant, the news is not as good. Already two workers have been found to have 10 times more radioactive iodine levels in their thyroid glands than their fellow workers, according to news reports. The two workers are not sick but have been stopped from working, according to reports. They will be monitored with more checkups.

<b>Microwave iodine</B>

Now researchers have found a new way to handle the radioactive iodine: radioactive forms of iodine can be immobilised by microwaves.

The idea is to make a solid that will contain the radioactive iodine, that can be disposed of in a proper manner. Professor Neil Hyatt and colleagues found that lead iodovanadinite(Pb5(VO4)3I) can work this way.

They heated a mixture of lead iodide, lead oxide and vanadium oxide with a microwave set at the frequency used in typical household microwave ovens to produce the Pb5(VO4)3I. This traps the iodine and keeps it from getting back into the air.

The material and process are being developed further, and it is hoped to develop a cheap and simple way to trap iodine that can easily be used in another nuclear accident.

Professor Neil Hyatt explained in a press release: "In spent nuclear fuel, the iodine is not immobilised, so once the containment is breached it simply gets dispersed.” He added "Our new method offers a way of safely and rapidly containing this radionuclide, reducing the potential long term impact on human health from discharge to the environment."