The operator of the Fukushima nuclear plant in Japan is preparing to remove 400 tonnes of highly irradiated spent fuel from a damaged reactor building.
The Tokyo Electric Power Company says it is a dangerous operation that has never been attempted before on this scale.
More than 1300 used fuel rod assemblies need to be removed from a building that is vulnerable to collapse if another large earthquake occurs.
The rods contain radiation equivalent to 14,000 times that released by the atomic bomb on Hiroshima in 1945.
The operation will begin in November at the plant's No. 4 reactor.
A mishap could lead to a worse disaster than the March 2011 nuclear crisis at Fukushima, which was the world's most serious since Chernobyl in 1986.
TEPCO has already removed two unused fuel assemblies from the pool in a test operation last year, but these rods are less dangerous than the spent bundles. Extracting spent fuel is a normal part of operations at a nuclear plant, but safely plucking them from a badly damaged reactor is unprecedented.
The company is already in a losing battle to stop radioactive water overflowing from another part of the facility.
Last week, Prime Minister Shinzo Abe ordered the government to take a more active role in controlling the overflow of radioactive water being flushed over the melted reactors in Units 1, 2 and 3 at the plant.