An assessment of the continuous neutron source using a low-energy electron accelerator

The performance of a continuous neutron source using an electron accelerator was evaluated by computer simulation codes (EGS4 and MCNP) in terms of neutron yield, neutron flux distribution, neutron spectrum, and heat distribution. Electrons with energies from 10 to 100 MeV were injected into a tungsten converter in order to generate photons by bremsstrahlung. When the photon irradiated a heavy water (DS2O) target, neutrons were produced by photonuclear reaction in the D2O target. This type of source was optimized for target geometry and electron energy from the point of neutron yield. The neutron spectrum was found to have two characteristic peaks, at the low-energy (thermal) region and the high-energy (million-electron-volt) region. The maximum photoneutrons per 1,000 MeV of electron energy was 0.56 at the electron energy of 30 MeV. In the case of irradiation by a 30-MeV, 33-mA continuous electron beam, the maximum thermal neutron flux was on the order of 1011 cm-2·s-1