Grain-boundary phosphorus segregation in highly neutron-irradiated reactor pressure vessel steels and its effect on irradiation embrittlement

•The grain-boundary P segregation for A533B RPV steels irradiated to high fluences in PWRs or a MTRs was analyzed using AES.•An increase in irradiation-induced grain-boundary P segregation was confirmed by a simulation based on a rate theory model as well as AES analysis.•No flux effect on grain-boundary P segregation was confirmed for A533B RPV steels with bulk P contents equivalent to that in RPV steels employed in Japanese nuclear power plants.•Intergranular embrittlement is not likely to occur for RPV steels with a bulk P content, which is higher than that of most U.S. A533B steels.