The operator of Japan's crippled Fukushima nuclear plant has started moving highly radioactive water to a storage facility.

TEPCO says it is planning to move 10,000 out of the 25,000 tons of the contaminated water in the basement of number two's reactor turbines within 26 days. That reactor is the one needing most urgent attention as the radioactive water is flooding its turbine building and a nearby underground trench.

Removing the water into storage is vital to restore the reactor's key cooling function.