Pressure vessel steels: influence of chemical composition on irradiation sensitivity

Neutron irradiation of steels used in the construction of nuclear reactor pressure vessels can lead to the embrittlement of these materials, i.e. increasing the ductile-to-brittle transition temperature and decreasing the fracture energy, which can limit the plant life. The knowledge of irradiation embrittlement and the means for minimizing such degradation is therefore important in the field of assuring the safety of nuclear power plants.

Irradiation embrittlement is quite a complex process. It involves many variables. The most important of these are irradiation temperature, neutron fluence (neutron dose), neutron flux (neutron dose rate) and chemical composition of the irradiated material. This paper is concerned with the effect of chemical composition, i.e. the role of residual and alloying elements in the irradiation embrittlement of nuclear reactor pressure vessel steels in light water reactors. It presents a critical review for the published work in this field over the last 25 years.