by Andy Johnson, CTV News:
More than a year after a devastating earthquake and tsunami triggered a massive nuclear disaster, experts are warning that Japan isn’t out of the woods yet and the worst nuclear storm the world has ever seen could be just one earthquake away from reality.
The troubled Reactor 4 at the Fukushima Daiichi nuclear plant is at the centre of this potential catastrophe. Reactor 4 — and to a lesser extent Reactor 3 — still hold large quantities of cooling waters surrounding spent nuclear fuel, all bound by a fragile concrete pool located 30 metres above the ground, and exposed to the elements.
A magnitude 7 or 7.5 earthquake would likely fracture that pool, and disaster would ensue, says Arnie Gundersen, a nuclear engineer with Fairewinds Energy Education who has visited the site.
The 1,535 spent fuel rods would become exposed to the air and would likely catch fire, with the most-recently added fuel rods igniting first.