Development of a novel simulated neutron pulse signal generator for flux measurement

Neutron flux measure systems perform an important role in both nuclear power plants and thermonuclear reactors. However, strong neutron sources are necessary to test these modern neutron flux monitoring systems. Due to the dangerous nature of neutron radiation, developers opt for simulated neutron signals instead. This paper details the design of a random pulse signal generator capable of perfectly reproducing high count rate neutron signals (up to 109 counts per-second) for the purpose of testing flux monitoring systems in-lab without any radiation source involved. Fully digitalized waveforms were created within FPGA to assure that important elements of neutron signal, including pulse shape, pulse amplitude spectrum, count rate, and add-on white noise intensity were all able to be accessed and changed separately over the PCI&PCIe bus. A Labview-based Human Machine Interface (HMI) was also built to show all of these aspects and allowed real-time modifications. When compared to other signal generators, our signal generator has a significantly longer non-repetitive waveform and higher performance capability. This made it a reliable way to diagnose flux measurement systems by comparing count rates set on the signal generator to record results.