Monitoring system of the fuel-Casette-free STATE of the control rod sleeves on the PAKS NPP.

Lifting the control rod sleeves (CRS) is one of the initial steps of the refuelling of the VVER-400-213 type reactor, which are operating at Paks NPP. If any fuel-cassette adheres to the CRS during its lift, it can result in unplanned exposure of the workers. The monitoring system has been recalibrated, because the first calibration of the monitoring system had been implemented 20 years ago, and Paks NPP had changed the fuel cycle from 12 months to 15 months.