Fuel rods inside one of the reactors at the Fukushima Daiichi nuclear power plant may have completely melted and bored most of the way through a concrete floor, the reactor\’s last line of defence before its steel outer casing, the plant\’s operator said.
Tokyo Electric Power (Tepco) said in a report that fuel inside reactor No 1 appeared to have dropped through its inner pressure vessel and into the outer containment vessel, indicating that the accident was more severe than first thought.
The worst thing that could happen (and it\’s possible to find this prediction if you\’re prepared to wage through the CiF comments section) is that there would be a meltdown, as there indeed was.
A meltdown which would lead to a very expensive puddle of metal and that\’s about it.
That\’s why they have inner and outer containments, with concrete between them. Fuel melts, fuel rods melt, hit the concrete and solidify. And even if the outer containment is breached then there\’s several more metres of concrete underneath which will solidify the molten metal.
You wouldn\’t actually want it to breach the outer containment, of course. Get quite a lot of nasty (but very local, no great clouds of stuff like at Chernobyl) radiation.
Very boring, very expensive, puddle of cold metal.
It\’s amazing how safe nuclear power is really…..