25 Juillet 2014
July 24, 2014
1.1 trillion becquerels of radioactivity leak during Fukushima cleanup
THE ASAHI SHIMBUN
More than 1 trillion becquerels of radioactive substances were released into the environment during debris-clearing work at the Fukushima No. 1 nuclear power plant last year, according to estimates by Tokyo Electric Power Co.
Although TEPCO's stricken facility is estimated to currently emit about 10 million becquerels per hour, the utility said that cleanup efforts at the plant’s No. 3 reactor on Aug. 19, 2013, resulted in the release of a maximum 1.1 trillion becquerels of radioactive materials over a period of four hours.
The figure was presented at a meeting of the Nuclear Regulation Authority on July 23.
“More careful countermeasures should have been taken,” said Toyoshi Fuketa, an NRA commissioner.
The estimates were made by monitoring results in downwind areas and also took into account that alarms for highly contaminated dust concentrations sounded for four hours.
The precise amount of radioactive substances that leaked out of the plant site remains unclear, TEPCO officials said.
The utility said the concentration levels were the highest during a 20-minute period, and it applied that figure for all of the four-hour cleanup effort. Therefore, TEPCO officials believe their final figure is probably an overestimate.
Since Aug. 19 last year, TEPCO has taken steps to prevent a recurrence, such as spraying anti-scattering agents not only before debris removal, but also after the operations. Dust concentration alarms have not sounded since the new precautions took effect, according to the company.
July 24, 2014
Up to 1.12 trillion becquerels of cesium was dispersed last summer as debris was removed from the battered building of reactor 3 at the Fukushima No. 1 nuclear plant, with tainted rice later being found in Miniamisoma, Fukushima Prefecture, according to Tokyo Electric.
Last Aug. 19, radiation-tainted dirt and dust was stirred up while the debris was removed from the unit, which was gutted by an explosion during the March 2011 meltdown crisis, Tokyo Electric Power Co. said Wednesday at a review meeting of the Nuclear Regulation Authority.
By Tepco’s estimate, up to 280 billion becquerels per hour of radiation were released into the environment over four hours. That’s 2,800 times the 10 billion becquerels per hour usually discharged from buildings at the crippled plant.
The work set off an warning alarm for airborne radiation at the plant and the cesium-tainted rice was found in paddies about 20 km north of the plant.
A southeast wind was blowing at the time of the removal work.
Tepco claims it was still not known whether the rice contamination had a causal connection with the work.