3D real-time in-core neutron flux mapping with micro-pocket fission detectors (MPFD)

A micro-pocket fission detector (MPFD) array is being deployed in the Kansas State University TRIGA Mark-II nuclear reactor in order to produce a real-time 3-dimensional neutron flux map. A total of 75 MPFD³-Ts make up the array where each MPFD³-T consists of an uncoated detector for background subtraction, a 93% enriched ²³⁵U coated detector for thermal neutron sensitivity, a natural uranium coated detector for mixed energy neutron sensitivity, and a thermocouple for thermal monitoring. The array is located in fixed in-core positions between fuel elements and is capable of being read out in pulse, MSV, and current modes allowing for operation from shutdown to full power. In addition, using off-the-shelf electronic components, the system is able to track reactor pulses with power changes spanning 7 orders of magnitude in less than 100 milliseconds.