The firm, which operates in the UK, US and Canada, is also working with the UK Government to decommission 22 of its nuclear plants.
As part of the contract, EnergySolutions will work with Toshiba Corporation to design and install an advanced liquid processing system to decontaminate the 125,000 cu m of seawater to meet strict safety limits set by the Japanese Government.
It will also provide the treatment and packaging of secondary wastes resulting from the water decontamination process.
Once decontaminated it is anticipated that the stored water, which contains a wide range of radioactive nuclides, will be reused by plant operator TEPCO (Tokyo Electric Power Company) as a coolant for the reactors.
EnergySolutions ceo Val Christensen, said: “We are honoured to have been chosen to work alongside Toshiba and TEPCO in tackling this complex problem on behalf of the Japanese people.
“It is an unprecedented challenge but we are confident that, by applying our proven technology and decades of waste experience, we can deliver the uniquely high levels of clean-up demanded and take the site a step closer to its ultimate remediation.”
Carys Matthews