Solid-state polymerization of acrylonitrile induced by reactor radiation, including recoil particles from a nuclear reaction of10B (n, α)7Li, was carried out at low temperature. It was observed from the experiments that the effect of the recoil particles on polymerization is significant. The effect is characterized by cross-linking of polymers produced, and formation of trans-vinylene and C≡C bonds conjugated with a bond C˭N group in the polymerization during irradiation.