Tokyo Electric Power Co. said a failure of communication may have been partly responsible for the exposure of workers to dangerous levels of radiation near the quake-damaged Fukushima No. 1 nuclear power plant's No. 3 reactor on Thursday.
Tokyo Electric Power Co. said a failure of communication may have been partly responsible for the exposure of workers to dangerous levels of radiation near the quake-damaged Fukushima No. 1 nuclear power plant's No. 3 reactor on Thursday.
Six days before the workers were exposed, a measurement of radiation levels in the basement of the turbine building for the No. 1 reactor had found radiation levels of 200 millisieverts per hour, close to the maximum level of 250 millisieverts allowed for workers.
But the workers were not told about those measurements before they began laying a cable at the turbine building for the No. 3 reactor from about 10:30 a.m. on Thursday.
Because the three workers found low radiation levels on Wednesday and thought that the turbine building was not ordinarily a location where radiation levels were high, the three continued to work despite getting their feet soaked in contaminated water.
The No. 3 reactor turbine building basement was flooded with about 15 centimeters of water. No water had been found the previous day.
The three suffered partial radiation exposure and were taken to the National Institute of Radiological Sciences on Friday for observation.
A TEPCO official at the Fukushima office apologized and said, "If we had cautioned workers at the various locations in the nuclear plant about the information obtained about the circumstances in the No. 1 reactor (turbine building), we feel we might have been able to prevent the latest radiation exposure."
TEPCO officials are considering removing seawater brought into the plant by the tsunami on March 11. As part of preparations for removing the water, water samples at the No. 1 reactor were taken at 9:30 a.m. Thursday and analyzed.
According to TEPCO and the Nuclear and Industrial Safety Agency (NISA) officials, radiation of about 3.8 million becquerels per cubic centimeter was detected at the No. 1 reactor turbine building. That is similar to the level of radiation found at the No. 3 reactor turbine building and about 10,000 times higher than normal for the coolant in the reactor core.
The types of radioactive materials found in the water sample were very similar to those found in the No. 3 reactor turbine building. The materials included cesium-137, which is contained in the fuel rods.
NISA officials believe the contaminated water likely came from the reactor rather than the storage pool containing spent fuel rods.
TEPCO officials also said water containing levels of radiation ranging between 200 and 300 millisieverts per hour was found in the basement of the turbine building for the No. 2 reactor.
That means highly radioactive water has accumulated on the floors of the turbine buildings for the No. 1, No. 2 and No. 3 reactors. TEPCO officials will look into pipe damage and other factors to determine how the water built up.
Water as much as 1.5 meters deep was found in the No. 3 reactor turbine building. The water was 1 meter deep in the No. 2 reactor turbine building and 40 centimeters deep in the No. 1 reactor turbine building.
In the No. 4 reactor turbine building, 80 centimeters of water has accumulated, although it is unclear if the water is contaminated by radiation.