The role of silicon on solute clustering and embrittlement in highly neutron-irradiated pressurized water reactor surveillance test specimens

•The role of Si content on irradiation embrittlement was clarified.•Solute atom clusters of highly neutron-irradiated Japanese pressurized water reactor surveillance test specimens were analyzed by atom probe tomography.•The cluster radius and number density decreased and increased, respectively, with increasing Si content, resulting in a constant volume fraction of SCs.•Increase in Si reduces the degree of irradiation embrittlement. This is consistent with the results of our previous study based on Bayesian statistical analysis.