Keywords: reator start-up, neutron detectors, mechanism, thermocouple, reed, pool-type fast reactors, nuclear fuel loading, plug rotation, core monitoring, control, instrumentation, nuclear energy, nuclear power
Control and instrumentation in start-up neutron detector handling mechanism in fast reactor
In pool-type fast reactor, during initial fuel loading, first approach to criticality and low power operations special provision is to be made in the central fuel sub-assembly to accommodate the neutron detectors in a guided assembly. This instrumented sub-assembly had to be retracted during fuel loading to facilitate plug rotation and then will be lowered again for core monitoring. This assembly is required during every start-up till the reactor runs for two months continuously at full power with fully loaded core. Else every time it is pulled up and kept in line with elevation of other neutron detectors in control plug during reactor operation once the power reaches ∼2 kWt. Towards this a motor with mobile assembly called Start-up Neutron Detector Handling Mechanism (SNDHM) is provided in the central canal plug. This paper deals with the process details and instrumentation developed towards this.