3 Septembre 2013
September 3, 2013
An academic society of nuclear engineers has come up with a proposal to dilute and release radioactive tritium into the sea as part of efforts to deal with the growing stockpile of radioactive water at the wrecked Fukushima No. 1 nuclear power plant.
The recommendation was released Sept. 2 as part of a draft final report of the Atomic Energy Society of Japan's investigation panel into the 2011 Fukushima nuclear disaster.
Tritium, a radioactive isotope of hydrogen, cannot be removed from radioactive water with treatment devices. The draft report said that diluting tritium to natural background levels and releasing it into the ocean was the only viable way of reducing the leakage risk of high-level radioactive substances.
The legal tritium concentration limit that can be released into the environment is 60,000 becquerels per liter, 1,000 times more lenient than that for radioactive cesium. Tritium does not concentrate in the bodies of living organisms because it behaves as a component of water, the investigation panel said.
The Fukushima No. 1 nuclear plant currently holds several tens of times the annual amount of tritium that can be released legally into the environment.
Satoru Tanaka, a nuclear engineering professor at the University of Tokyo who heads the AESJ investigation panel, said consideration should be given to reviewing the annual release limit.
"(The Fukushima No. 1 plant) is not a nuclear plant in normal conditions," Tanaka said. "The overall risk should be reduced."
The draft report also criticized Tokyo Electric Power Co., the plant operator, and Japan's nuclear regulatory authorities, saying their insufficient preparedness for a tsunami and other catastrophic situations was the direct cause of the reactor meltdowns at the Fukushima plant.
The draft report was scheduled to be presented to an AESJ fall meeting that opened in Aomori Prefecture on Sept. 3. It is expected to be finalized by year-end.