24 Février 2015
February 24, 2015
No workers believed exposed in brief rise in radioactivity in drain water
FUKUSHIMA, February 24, 2015-The Tokyo Electric Power Company is investigating the cause of a brief rise in the radioactivity of drainage water on Sunday and will make its findings public.
No workers are believed to have been exposed when measurements of the "gross beta" nuclides (total amount of nuclides that emit beta rays such as Strontium90) rose from below 1,500 to between 5,050 and 7,230 becquerels per liter of water. Although some of the water is believed to have reached the sea, measurements of radioactivity in the port area adjacent to the plant did not show any significant increase. The company also patrolled each tank facility and confirmed no leakage. Recent water radioactivity measurements are posted at http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150223_01-e.pdf.
TEPCO will increase the frequency of some ocean water sampling from once a week to daily during the investigation period. Ordinarily, TEPCO requires that any water discharged into the sea have "gross beta" levels below 5 becquerels per liter.
Plant operators were automatically alerted to the increase in radioactivity by sensors designed for that purpose. The air radiation dose monitored in the vicinity of drainage route at the time of the alarm did not show any significant changes. After confirming that the measurement results of the water pumped up from the drainage has returned to normal, TEPCO resumed drainage operations.
The company is investigating the potential causes of the event and will report its findings promptly.
For the location of the drainage and related materials, please go to http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150222_01-e.pdf