Design of a neutron flux measurement channel using the ionization chamber KNK-3 at the Dalat Nuclear Research Reactor

Abstract

This paper presents a design of the neutron flux measurement channel that consists of a Boron-contained gamma-compensated ionization chamber (CIC) named KNK-3 and operates in current mode, a current to frequency (I to F) converter, and a neutron flux measurement and control module (FPGA-WR). The designed measuring channel allows to measure and control the neutron flux density from 1.0x10⁶ to 1.2x10¹⁰ n/cm².s corresponding to the range from 0.1 to 120% of the nominal power of 500 kW of the Dalat nuclear research reactor (DNRR). The measurement and control module uses FPGA Artix-7 and digital signal processing algorithms to measure and calculate the reactor power and period values and generate warning and emergency signals by the reactor power and period. The measurement channel was tested by using simulated signals and examining in the reactor to compare with the neutron flux measurement channel using the BPM-107R neutron flux controller of the existing complex ASUZ-14R for the DNRR control and protection system (CPS). The comparison results show that the measurement channel fully meets the requirements on the accuracy of the reactor power and period parameters as well as the ability to respond at once to the warning and emergency signals of the reactor power and period. Therefore, the measurement channel can be used for testing, research, and training. The FPGA-WR measurement and control module can replace the BPM-107R controller for the working range of the CPS.