[en] With the use of finite element simulations the effect of austenitic corrosion resistant weld deposited cladding on WWER pressure vessel integrity under pressurized thermal shock on emergency is investigated. The calculation of thermal and stress fields is made with accounting for distinctions between properties of vessel base metal and those of cladding material as well as taking into consideration a substantial loss of plasticity in austenitic steel under irradiation. The results of integrity assessment within the framework of elastic-plastic fracture theory show that the role of the cladding in reactor vessel failure is greatly dependent of reactor lifetime. It is concluded that the presently accepted standard calculations of stresses without accounting for embrittlement of the austenitic layer during the whole reactor service life result in underestimated values of stresses in weld deposited cladding