COOLING DEVICE OF SPENT FUEL POOL AND COOLING METHOD THEREOF

PROBLEM TO BE SOLVED: To provide a technique for passively cooling a spent fuel pool, which can easily be additionally installed in even an existing plant without reducing a preservation space for spent fuel.SOLUTION: A cooling device 10 for a spent fuel pool includes: a coolant which is liquid when pool water 12 for removing decay heat of a spent fuel 11 is at a normal set temperature, and is evaporated at a temperature higher than the normal set temperature; a heat receiving part 20 which holds the coolant and is immersed in the pool water 12; a transfer circuit 14 which transfers a coolant 25 evaporated in the heat receiving part 20 to a heat dissipation part 13; a return circuit 15 which returns a liquid coolant 26 condensed in the heat dissipation part 13 to the heat receiving part 20.