Radiation gamma annealing of the WWER reactor vessel steel

Variation of the viscobrittle transition temperature Delta T of the vessel steel of the decommisioned WWER reactors is analyzed. It is shown that Delta T depends on the gamma quanta flux density at the same neutron fluence. It is established that cold brittleness temperature variation decreases with increasing gamma radiation flux density at the constant neutron fluence. Result analysis of the weld metal shows that increasing the gamma quanta flux from 5mult 10 exp 11 up to 5mult 10 exp 12 s exp -1 cm exp -2 may lead to a noticeable increase of the neutron fluence necessary for obtaining a given Delta T.