Application of FPGA in the radiation environment of accelerator driven sub-critical system

Field programmable gate arrays (FPGAs) are gaining increased attention worldwide for application in the instrumentation and control systems for nuclear power plants. In this paper, we study potential application of FPGAs in the radiation environment of an accelerator driven sub-critical (ADS) system, where a spallation target located at the centre of a sub-critical core is bombarded by the high-energy protons from an accelerator. In comparison with a commercial reactor used in nuclear industry, more control electronics are required in the reactor building of an ADS system to exactly couple the high-energy beam from the accelerator to the spallation target in the reactor core. By estimating the neutron flux in the reactor building of China initiative ADS system which should be able to demonstrate the ADS concept at 10 MW power level, we observe that the neutron-induced displacement damage and single event effect are serious. Thus, we suggest to shield these semiconductor devices with shielding materials, such as polyethylene or concrete. Neutron shielding simulations by using GEANT4 with G4 neutron data library (G4NDL) have indicated that the polyethylene material with a thickness of 30 cm can reduce the neutron dose up to three order of magnitudes and thus reduce dramatically the neutron-induced radiation effects. By assessing the displacement damages and soft errors caused by the neutrons with various energies, we observe that the most effective neutrons in creating radiation damages are those fast neutrons with the energy of more than 0.1 MeV. Therefore, we suggest to add heavy metals in the shielding material to further shield these fast neutrons. (author)