RosRAO, a subsidiary of Russian nuclear giant Rosatom, is among the three companies selected to build a system to filter radioactive tritium out of the contaminated water collected at the stricken power plant – a task that has so far defied engineers.

Fukushima Daiichi operator TEPCO, which has resorted to erecting thousands of water tanks to contain the toxic run-off from the plant, is already trialing a system that filters 62 radioactive materials. But the Advanced Liquid Processing System (ALPS) does not filter tritium, a mildly radioactive byproduct of nuclear generation, which nonetheless means that water cannot be safely discharged into the Pacific Ocean.

RosRAO, which was built on the foundations of Soviet-era waste disposal research institutions, won the TEPCO tender for a filtration system - alongside US firm Kurion Inc, and GE Hitachi Canada, a joint project between the Japanese and US corporations - beating 26 other companies.

Each of the three contractors will be given 1 billion yen – about $9.5 million – to present a working filter prototype by the March 2016 deadline, and the final value of the contract, which could last for decades, could run into hundreds of million dollars.

“We are offering a unique combined filtering technology, unlike our Western colleagues, which allows it to be more cost-efficient,” said project manager Sergey Florya in an interview with RIA Novosti news agency.

The official added that the level of tritium in Fukushima water is 10,000 times higher than the norm allowed by the WHO.

TEPCO faces an estimated bill of over $105 billion to clear up the consequences of the earthquake and tsunami that caused multiple meltdowns at the partially-antiquated plant in March 2011.

While all reactors have been stabilized, cooling water disposal has been a prime issue. The multi-nuclide removal equipment, called ALPS (advanced liquid processing system) was installed in March 2013, but its functional usefulness has been hampered by problems, such as pipe corrosion, leaks, operator errors and design imperfections, which have forced constant shutdowns. At one point its filters were failing to decontaminate the water at all, despite purportedly working as designed.

To this day, ALPS remains in “trial mode”, despite the government ordering a $150 million expansion to the system, tentatively scheduled to begin operating in October.

Latest statistics show that there are currently 367,000 tons of contaminated water, stored in tanks inside the Fukushima Daiichi nuclear power plant.

“This is the first time this much radioactive water has been collected in any single place in the world – the scale of this project in unprecedented,” said Florya.