Fukushima NPP

mark1 reactor posted by (C)tetsu-jp

developement late 1960s.

control rods are inserted upwards from the bottom.
spent storage pool on top of the containment building.
torus structure to collect cooling liquid.

designed for 40 years lifecycle.
many small incidents since 2005 (all not critical).

2011 loss of cooling system due to 9.0 earthquake.
this reactor was not designed for a 9.0 earthquake.
additionally, backup generators were knocked off by tsunami.

it is believed now that the reactors are too much damaged to become restarted.
core container is still intact.
there is no graphite shell like in Russia 1986 that could catch fire.

the spent fuel pools are an additional problem.

there are 23 of these reactors still being used in the USA.

Fukushima NPP radiation outside containment building: 400 msv/hour
Chernobyl NPP (1986) 80,000 - 1,600,000 msv/hour

The distribution of radioactive dusts was greatly accelerated by the graphite shell
that caught fire.