“Two things were needed to minimise the risk. First, the pool had to be drained, but its two valves in the basement – which could only be turned by hand – were now submerged under radioactive water from the firemen’s failed attempt to extinguish the reactor fire. Second, the commission decided that the earth beneath the reactor building should be frozen with liquid nitrogen to harden the ground, support the foundations and help to cool the superheated core.”
