‘Ethereal Blue Flash’
Nuclear experts call such reactions "localized criticality." They consist of a burst of heat, radiation and sometimes an "ethereal blue flash," according to the U.S. Energy Department’s Los Alamos National Laboratory website. Twenty-one workers worldwide have been killed by criticality accidents since 1945, the site said.
(Source: Bloomberg)
This is where it gets scary, no one fully understand these nuclear events. This is the very edge of nuclear science. At the same time TEPCO is saying – don’t worry we’ve got this baby under control, really, why would we lie about such a thing.