The study of irradiated samples is of considerable importance. Owing to these samples being radioactive, the applicability of conventional characterization methods is limited. Because of the high sensitivity of ³He detectors to neutrons, the small-angle neutron scattering (SANS) technique is nearly unaffected by radiation such as gamma, beta rays, and sample preparation is simple.

This study aims to develop a device for SANS measurement of nanostructures in radioactive samples.

The shielding thickness of the device was optimized through Monte Carlo simulations. Experimental efficiency and safety of the device were improved by combining remote-control functionality and automated sample switching among up to 12 samples loaded simultaneously. Finally, the device was used to carry out a SANS experiment for characterizing the radioactive A508-III steel sample.

The optimized thickness of the lead shielding layer of the device is 7.5 cm, the corresponding maximum dose rate of the measurable radioactive sample is 1.4 mSv·h^-1. The results of successful SANS experiment on a A508-III steel irradiation surveillance specimen indicate that low-dose, long-term irradiation has a minimal impact on the nanostructure of pressure vessel steel.

The device and associated technical methods can be applied for nanostructure characterization of radioactive samples.