The Tokyo Electric Power Company is trying to decide what to do with the largest pool of radioactive water in the history of nuclear accidents. It can either dump it in the ocean, let it evaporate into the air, or both.

The more than 330,000 tonnes of water with varying levels of toxicity is stored in pits, basements and hundreds of tanks at the wrecked Fukushima nuclear plant.

Leaks: Nuclear regulators inspect the storage tanks. Credit:Reuters

The government said this week it would take a bigger role in trying to staunch the toxic outflow that has grown to 40 times the volume accumulated in the atomic disaster at Three Mile Island in the US.

Processing and disposing of the water - enough to fill a large crude oil tanker or 132 Olympic-size swimming pools - is presenting one of the most challenging engineering tasks of our generation, former nuclear engineer Michael Friedlander said.