The [Japanese] government picked three overseas companies to participate in a subsidized project to determine the best available technology for separating radioactive tritium from the toxic water building up at the Fukushima No. 1 nuclear plant. Tokyo Electric Power Co. is currently test-running a system it says is capable of removing 62 types of radioactive substances from the contaminated water, but not tritium. Thus tritium-laced water is expected to accumulate at the plant in the absence of any method to remove the isotope.
The three firms chosen from 29 applicants are U.S. firm Kurion Inc., which offers technologies to treat nuclear and hazardous waste; GE Hitachi Nuclear Energy Canada Inc., a joint venture of Hitachi Ltd. and U.S. firm General Electric Co.; and Federal State Unitary Enterprise RosRAO, a Russian radioactive waste management firm.
The government will provide up to ¥1 billion for each examination of the technologies and running costs, and consider whether any of them can be applied to treat the water at Fukushima No. 1, the industry ministry said. The three companies are to conclude their experiments by the end of March 2016, a ministry official said. The official cautioned there is no guarantee that any of the technologies will be put to practical use.
Three firms picked to help tackle toxic water at Fukushima No. 1, Japan Times, Aug. 26, 2014
In January 2014 it was made public that a total of 875 terabecquerels (2.45 g) of tritium are on the site of Fukushima Daiichi,and the amount of tritium contained in the contaminated water is increasing by approximately 230 terabecquerel (0.64 g) per year. According to a report by Tepco “Tritium could be separated theoretically, but there is no practical separation technology on an industrial scale.” See Wikipedia