But by the next evening, Valery Legasov and the team of scientists analyzing the latest data from Unit Four had made a horrifying and apparently inexplicable discovery. Instead of continuing to fall, the radioactive releases from the reactor had now suddenly begun to increase again, doubling from 3 million to 6 million curies overnight. The temperature of the burning core, too, was rising rapidly. By Thursday night, Legasov’s estimates suggested that it was already approaching 1,700 degrees centigrade.
