Neutron energy spectra were simulated by the MCNP code.The neutron energy spectra and corresponding average energy of off-coupling box
irradiation channel and outer surface of the off-coupling cover were calculated.The results indicate that about 90% neutrons are in the energy range of 0.05–3 MeV.The average neutron energy of off-coupling box and irradiation channel present "S" shape along distance
and space asymmetry must be considered.The average neutron energy above off-coupling cover’s 45° woof fluctuates slightly and it is an appropriate irradiation area.