There are quite a few engineering plastics around which are irradiation resistant and could suit your applications, such as PA, PSU, PES, PEEK (reinforced or not). The following materials are not generally suitable for irradiation : PP, PTFE, Acetal and PVC. Also, impact modified materials containing rubbery phases such as ABS should be treated with care, since the rubbery phase may crosslink and embrittle the material.