French Case Study at EDF (International Case Study on Organization and Detailed Technical Aspects of NPP Outage Decontamination)

The radiological surveillance program of French NPPs is based on the monitoring of 3 indices, measured at the beginning of refuelling outages. These indices are used to mark the radiological level of the circuits. - The loop index represents the overall state of the primary circuit contamination; - The reactor building (RB) index shows the contamination state of RB and auxiliary circuits; - The so-called 'Cd-Zn-Te gamma spectrometry' allows to define the origin of the contamination: ⁶⁰Co, ^110mAg, etc. It also helps select the chemical process to be implemented for decontamination if needed. These three indices are specified in a table. They are measured under the same conditions in each French NPP.