Irradiated fuel assemblies—essentially bundles of fuel rods with zirconium alloy cladding sheathing uranium dioxide fuel pellets—that have been removed from a nuclear reactor (spent fuel) generate a great deal of heat from the radioactive decay of the nuclear fuel’s unstable fission products. This heat source is termed decay heat. Spent fuel is so thermally hot and radioactive that it must be submerged in circulating water and cooled in a storage pool (spent fuel pool) for several years before it can be moved to dry storage.
This article was written by Mark Leyse and originally published by The Bulletin Of The Atomic Scientists.
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