Cladding rupture life control methods for a power-cycling WWER-1000 nuclear unit

Using the cladding creep energy theory, taking into account the WWER-1000 fuel assembly four-year operating period transposition algorithm, as well as considering the disposition of control rods, the location of the axial segment limiting the fuel cladding operation time, at day cycle power maneuvering, has been found. It has been shown that the WWER-1000 fuel element cladding rupture life, at normal variable loading operation conditions, can be controlled by an optimal assignment of the coolant temperature regime and the fuel assembly transposition algorithm.

► The sixth axial segment limits the WWER-1000 fuel cladding lifetime.
► Keeping the inlet coolant temperature constant stabilizes the axial offset.
► The coolant temperature and the fuel transfer method set the cladding lifetime.