Off-clock radiation exposure ignored


The health ministry is not calculating how much radiation workers at the Fukushima No. 1 power plant absorbed after they evacuated or while off the clock, casting doubt on the adequacy of the current radiation control regime.

The Health, Labor and Welfare Ministry also does not intend to assess radiation exposure for workers engaged in decontamination efforts around the badly damaged plant in Fukushima Prefecture, government officials and supporters of the workers said Saturday.

The ministry currently keeps track of radiation doses when nuclear workers are actually at work. The maximum doses for the workers and those involved in decontamination efforts are 100 millisieverts over five years and 50 millisieverts a year.

The officials said the ministry takes the position that in controlling radiation dosage, it makes a distinction between work and personal life because the measures taken to mitigate exposure differ between them.

“No matter where they are exposed to radiation, it’s the same thing for an individual,” said Katsuyasu Iida, who works on securing the health of nuclear plant workers as head of the secretariat for the Tokyo Occupational Safety and Health Center.

Noting that the health ministry is developing a database to record radiation doses separately from the one compiled by the Radiation Effects Association, Iida said that by employing such a database, total dosage “should be strictly controlled by adding up doses received when they are not at work.”

Those who enter controlled zones at nuclear plants carry a booklet used to keep track of radiation exposure while working. The data are sent to the Radiation Effects Association in Tokyo, which keeps track of the accumulated doses at whatever plants they go to work at and for whatever employer they work for. Those whose radiation doses exceed the limits are barred from further work.

All of the workers at Fukushima No. 1 carry dosimeters while working or moving between the plant and an accident response base nearby. Radiation exposure during evacuations following the accident and while away from work are being projected on the basis of radiation levels at observation points.

In its report last December, the Fukushima Prefectural Government estimated that evacuees from 12 municipalities around the plant were externally exposed to up to 19 millisieverts of radiation over the four months from the start of the disaster, which followed the March 11 megaquake and tsunami.