Probably the last thing plant operator Ouchi Hisashi saw before he passed out was a blue flash in the concentration of uranium he was mixing in a steel vat.

CNN: 'We're Scared for Our Baby'

What they failed to appreciate, and what the company failed to tell them, was that a fast-breeder uses fuel that has a 19% concentration of the fissile isotope of uranium, 235U. Ordinary nuclear reactors use fuel containing around 3% of the fissile isotope.

ECONOMIST: All over in a flash