Six workers were exposed to contaminated water at Fukushima Daiichi this week, while the site also experienced an interruption to its electrical supply and slightly elevated levels of cesium were detected in ocean water near the plant.
Recent developments related to the Tokyo Electric Power Co. reactors blacked out following Japan's 2011 earthquake and tsunami include:
Spill Contained in Treatment Building
A worker's error resulted in 7 metric tons of contaminated water leaking inside a building housing a desalination system Wednesday. According to TEPCO, the leak was confined to the building, but it contaminated six workers with water containing radioactive materials emitting a dose of 1.2 millisieverts per hour at the water's surface. In a follow-up release the same day, TEPCO reported that the workers were successfully decontaminated.
Power to Unit 1 Interrupted
On Monday, an alarm indicated part of Fukushima Daiichi's on-site common power supply had been cut after a worker mistakenly hit a button that activated a breaker. According to reports from TEPCO, this stopped a reactor water injection pump for the condensate storage tank of unit 1. Another pump automatically activated to replace it. The breaker trip also cut power to an exhaust fan in the unit 2 reactor building. The affected power panels were restored within three hours.
Cesium Detected in Waters Near Plant
TEPCO reported finding detectable levels of cesium 137 in water samples taken 1 kilometer offshore from the plant Tuesday. At 1.4 becquerels per liter, the concentration was below the 10 becquerels per liter World Health Organization guideline for drinking water, and samples taken Thursday fell below the detection limit of 0.5 becquerels per liter. Nonetheless, the temporary increase occurred amid mounting concerns about contaminated groundwater and surface runoff making its way into the sea.