Optimizing the life cycle of nuclear systems under safety constraints requires high-performance experimental programs to reduce uncertainties on margins and limits. In addition to improvement in modeling and simulation, innovation in instrumentation is crucial for analytical and integral experiments conducted in research reactors.

Significant efforts have been made recently to improve in-pile instrumentation for the benefit of material testing reactors. The quality of nuclear research programs obviously relies on an excellent knowledge of their experimental environment, which constantly calls for better online determination of neutron and gamma flux. But the combination of continuously increasing scientific requirements and new experimental domains - brought, for example, by Generation-IV programs - also necessitates major innovations for in-pile measurements of temperature, dimensions, pressure, or chemical analysis in innovative mediums.

To face these challenges, the CEA (French Nuclear Energy Commission) and the SCK.CEN (Belgian Nuclear Research Centre) have combined their efforts and now share common developments through a Joint Instrumentation Laboratory.

Significant advances have thus been obtained in the field of in-pile measurements, on one hand by the improvement of existing measurement methods (for example, a unique fast neutron flux measurement system using fission chambers with 242Pu deposit and a specific online data processing has been developed), and on the other hand by the introduction in research reactors of original techniques such as optical dimensional measurements or acoustical fission gas release measurements.