Instrumentation of radiological data collection processes for the remediation, dismantling and decommissioning (A and D2) of nuclear facilities

The D and D industry is a mature industry. In France, this is assessed by the results obtained on the site of Grenoble, and technological breakthroughs such as the implementation of the MAESTRO robotic equipment confirm it.The processes are implemented in complex contexts and are adapted to answer different technical configurations: nuclear reactors, research laboratories, spent fuel reprocessing plants... The efficiency of the processes lies in the control of three generic phases (high-level functions) of the manufacturing industry: 1) the management of the storages, 2) the treatment (put in the physical and radiological template) then 3) the waste produced. The common point is the management of a term source (Bq). Every stage of the process of A and D2 is governed from the evaluation of the radiological levels. Thus the nuclear instrumentation is a major function in the implementation and the control of the processes of A and D2. In operation, the main part of the radiological, chemical and physical characterization devices of the industrial plant at its end of life cycle is concentrated on the waste packages. These equipments are maintained in the phase of A*D2. They are completed by measure and control devices distributed on all the processes, from the integrated standing equipment to the waste package in its final storage. The functional and logical architecture of this instrumentation may be represented by a diagram of instrumentation where the equipments are first used to characterize radiological environments to be dismantled, then, to govern the treatment and dismantling processes and, at the end of line, to control the final waste packages or the plant released from the radiological constraints.The measure of gamma radiations and neutron dominates the non-destructive techniques of analysis. The spectrometry gamma remains the reference technique in A*D2. Its implementation was facilitated thanks to the advent of detectors working at room temperature (CdZnTe, LaBr₃). For the complex hot cells, the result of the gamma spectrum processing is combined with techniques for localization of the hot spots. The combined processing of the measurement results is insured by the exploitation of digital methods to draw the efficiency curves and to estimate the uncertainty associated with the physical quantity of interest.The characterization of the waste of the A*D2 strengthened the use of the coupled methods: chemical and physical analysis, gam-ma spectrometry, gamma imaging and neutron counting. These methods are propagated on the whole waste production line and for the nuclear facility decommissioning. This new concept of complete production line opens numerous technological and scientific working areas. (author)