Neutron in-core measurement channels
The self-powered detectors with a rhodium emitter are used to determine the output distribution in the core of the VVER reactors (in-core measurement). Generally speaking, the self-powered detectors are single-core or two-core cables with mineral insulation, and their active part contains a rhodium wire of high purity.
The detectors are positioned in the core of a reactor in arrays called the neutron in-core measurement channels (KNI). The channels go through the reactor lid and are inserted at 36 coordinates into the core of the VVER 440 reactor, and 64 coordinates as is the case of the VVER 1000 reactor. Each channel contains seven detectors, evenly distributed along height of the core. The KNI channels (based on type) are up to twelve meters long. Because of rhodium burn-up, these detectors have to be replaced regularly with new ones, as part of the reactor maintenance. ŠKODA JS has manufactured and supplied more than 1,200 KNI channels to VVER reactor operators in the Czech Republic, Hungary, Slovakia and Ukraine.
Photogallery on the topic
Neutron flux measurement channels
Neutron flux measurement channels
