The electron accelerator driven sub-critical system

Abstract

We reference a typical pressurized water reactor and design an electron accelerator driven subcritical system (eADS), the reactor is a thermal reactor. The physics to create external neutrons in eADS is different to the spallation reactions which are used in the proton accelerator driven ADS system.The neutron energy spectra in eADS system are the combination of neutron energy spectra from photonuclear reactions and fission reactions. Simulation calculation shows that the neutron energy spectra from photonuclear reactions and from fission reactions have a remarkably difference. A large portion of neutrons emitted from the photonuclear reaction target is peaked in the energy region 10-8 ∼ 10-7MeV, the neutrons within this energy region are well thermalized neutrons which are readily absorbed by the fissile isotopes to split and release energy.The power peaking factors are greater than 2.0 in the eADS system driven by one and five electron accelerator(s). After rearranging the burnable poison rods in 1.6 % and 2.4 % fuel enrichment assemblies and inserting some burnable poison rods in the fuel assemblies with 3.1 % enrichment in the periphery area of reactor core, the power peaking factors can be reduced to about 1.2. The multiple electron accelerators in the subcritical system flatten the neutron flux distribution and improve the power peaking factors. Our calculation results indicate that with the symmetrical distribution of the four electron targets about the electron target on the center of the reactor core, the larger the radius of other four electron targets to the center of reactor core, the higher the keff and the lower the power peaking factors. This implies that in designing an eADS system all the electron targets should be in the periphery area of the reactor core except the electron target on the center.The electron accelerator driven system may be the real next generation reactor to burn depleted nuclear fuel, generate electric power and transmute nuclear wastes, is promising and deserves to explore with.