Evaluation of the neutron power signal calibration by the digital NMS applied to the research reactor

The neutron measurement system (NMS) used in research reactors to measure thermal neutron flux emitted from the reactor core, provides the neutron power signal that controls the reactor power with control rods. The neutron power signals from NMS are key components of the reactor protection system (RPS) and the reactor regulating system (RRS). Therefore, the NMS having accuracy and reliability is a significant component in the reactor operation. In particular, the linearity in the transition range between the pulse count and Campbell signal, as well as, the log power and linear power signal is considered a top requirement for reactor power control. However, analogue-based NMS has had difficulties in fitting the curve of different signals, such as, the pulse count and Campbell signal. Moreover, the full power alignment cost much trial and error. Digital NMS in research reactors, herein, which are being applied to Jordan Research and Training Reactor (JRTR), can improve the linearity performance and save time by using implemented calibration method. Herein, the detailed calibration of digital NMS is introduced and the implementation method is described in detail with actual test results. The digital NMS can be divided by three parts, the sensor (detector and its cables), field cables, and the signal processing assembly which consists of the preamplifier and signal-processing unit. [Display omitted]