Most of the irradiators that undertake the fundamental dosimetry studies are installed with radioactive sources of high-specific activity, which are only approved to be transported by qualified containers before the onsite loading being performed.

This study aims to design a novel irradiator featuring triple screen functionality to comply with the international and domestic regulation on the transportation of the radioactive source.

Firstly, based on the precise construction of the irradiator, a comprehensive simulation was conducted to analyze the control characteristics of the irradiation device on the beam according to the accurate modelling for the irradiator. Then, detailed simulation and analysis was performed in order to obtain the properties of the field in terms of radiation dosimetry research interests. Finally, a novel irradiator featuring triple screen functionality was implemented to facilitate the onsite installation and the following work.

This novel irradiator is appropriate to perform the onsite loading for the radioactive source. The scattered components in the spectrum can be reduced by 25% with the presence of a scattering chamber in the irradiator. The leakage radiation in the normal working area can be decreased by 7 orders of magnitude due to the triple screening functionality of the irradiator, the optimization is proposed for installation of the key components in the irradiator. The deformation of the spectra in the radiation field caused by the collimator complex is about 0.2%. The wall effect in the course of the absolute measurement of air kerma for three types of typical ionization chamber is calculated in the ⁶⁰Co γ radiation field, and the correction factors diverge less than 0.2% from the ones in the earlier publications.

The irradiator designed and implemented in this study can be a proper candidate to support the radiation dosimetry related work under the current regulation. The compact structure enables the irradiator to provide an extended dynamic range of dose rate, leading to a relatively long period of service.