Tokyo Electric Power Co. announced some welcome news this week, as the temperature within the last of three damaged reactor vessels at the Fukushima Daiichi nuclear plant fell below boiling. Meanwhile, the Japanese government offered more details about the scope of contamination from the accident and the cleanup to come.
Developments this week include:
Last Reactor Falls Below 100 C
For the first time since the accident began following a tsunami and station blackout in March, the water temperature in unit 2 fell below boiling.
TEPCO reported the temperature inside the reactor pressure vessel was 99.4 C and falling Wednesday. The development comes after crews began gradually injecting water from a nozzle at the top of the RPV, in addition to an opening at the bottom, with a total of 10 metric tons per hour being injected as of Monday, the Daily Yomiuri reported.
Temperatures inside the two other damaged RPVs at the plant dropped below boiling in July and earlier this month. Despite the temperatures, TEPCO said it will not describe the units as having reached cold shutdown status until radiation emissions fall further, which the utility believes it can now accomplish by the end of the year.
Environment Ministry: 29 Million Cubic Meters of Material to Be Removed
In the first estimate of its kind, a Japanese government report released Tuesday set a goal of cleaning up all contaminated areas with projected yearly doses of 5 millisieverts or higher, the Asahi Shimbun reported.
To do so will involve removing the top 5 centimeters of soil from an expanse equal to 13 percent of Fukushima Prefecture. Additional areas to be decontaminated include “hot spots” in urban areas, like some ditches and gutters, where yearly dose is expected to exceed 1 millisievert (not including background radiation). Of the area to be decontaminated, 70 percent is forest, where cleanup will involve clearing fallen leaves and trimming tree branches.
Most work is scheduled to begin next year, and the cleanup is expected to remove 29 million cubic meters of soil, leaves and debris. The government’s goal is to cut dose levels in contaminated areas by half over two years.