– Radiation tests lacking / Nuclear plant workers unsure of internal exposure levels (The Yomiuri Shimbun, May 19, 2011):
Nearly two months after the start of the crisis at the Fukushima No. 1 nuclear power plant, only 10 percent of workers there had been tested for internal radiation exposure caused by inhalation or ingestion of radioactive substances, due to a shortage of testing equipment available for them.
Tokyo Electric Power Co., operator of the crippled nuclear compound, is finding it impossible to use testing apparatus set up inside the facility because of high radiation levels recorded near the equipment.
A number of personnel working to overcome the nuclear crisis at the facility are increasingly alarmed by their lack of internal exposure testing. Some have said they may have to continue to work at the facility without knowing whether their radiation exposure levels have exceeded the upper limit set by the government.
On Tuesday, the government revealed a timetable for ending the nuclear crisis. The road map called for increased surveillance of the workers’ radiation levels, including a measure requiring TEPCO to periodically report such data to the government.
Internal exposure is caused by taking radioactive substances into the body via eating, drinking or breathing. Its unit, counts per minute (cpm), indicates the amount of radiation emitted per minute.
Regulations on preventing health problems caused by ionizing radiation require operators of power plants to conduct internal exposure tests every three months on plant employees who enter areas designated by laws and regulations on radiation-related health problems.
“My measured value [of radioactive exposure] exceeded the standard value by a double-digit factor. That’s never happened before,” said a plant worker in his 20s, recalling the time he saw the results of a test he took outside Fukushima Prefecture in early May.
The man, an employee of a company that works with TEPCO, installed power cables near a reactor building at the plant for a month beginning at the end of March.
The test is conducted by a device called a “whole-body counter.”
While a normal internal radiation level would range from several hundred cpm to 1,000 cpm, he was told his level was 30,000 cpm.
High levels of radiation emitted by debris were measured in his work area.
Although the masks worn by workers are supposed to be changed every three hours, he was told by a management company that he did not have to change his if there was no radioactive contamination.
He therefore used a single mask for five to six hours.
He ate in a building that houses an emergency headquarters and accommodates plant workers. At the end of April, he was notified that the building was also radiation-contaminated.
“I’ve probably taken in radioactivity while eating,” he said.
After the crisis at the plant began, the central government increased the maximum limit of radiation exposure from 100 millisieverts to 250 millisieverts exclusively for workers at the Fukushima plant.
However, the amount is a total of internal and external exposure doses. Workers can learn only their external doses via the measurement equipment they carry with them, and it is necessary to also measure their internal exposure level to verify whether their total exposure doses exceed the limit.
According to TEPCO, there are only three whole-body counters available near the plant. Some workers had to be tested as far away as the Kashiwazaki-Kariwa nuclear plant in Niigata Prefecture.
As of May 8, 630 workers, or just 10 percent of all workers at the plant, had taken the test.
The Health, Labor and Welfare Ministry’s Industrial Health Division has advised TEPCO to provide more tests. TEPCO has said it will increase the amount of test equipment on hand to 14 whole-body counters and will also raise the frequency of the test to more than once in three months.