Effect of swift heavy ion irradiations in polycrystalline aluminum nitride

13International audienceThanks to its high thermal conductivity, aluminum nitride may be a serious candidate as fuel coating for the Gas Fast Reactor. However, its behavior under irradiation is not entirely well understood. In order to catch a glimpse of this behavior, specimens were irradiated with swift heavy ions of different energies then characterised by both thermally stimulated luminescence and optical absorption spectrophotometry. With these techniques, the native defects, as well as those affected by irradiation, were identified: thus, by comparison to the virgin sample, no new defect detectable by these techniques is created by irradiations. Eventually, the fact that these techniques complement each other allowed to understand the effect of irradiation parameters on the defect concentration

Characterization and localization of partial-discharge-induced pulses in fission chambers designed for sodium-cooled fast reactors

During the operation of the Superphenix and Phenix reactors, an aberrant electrical signal was detected from the fission chambers used for neutron flux monitoring. This signal, thought to be due to partial electrical discharge (PD) is similar to the signal resulting from neutron interactions, and is generated in fission chambers at temperatures above 400°C. This paper reports work on the characterization and localization of the source of this electrical signal in a High Temperature Fission Chamber (HTFC). The dependence of the shape of the PD or neutron signal on the various experimental parameters (nature and pressure of the chamber filling gas, electrode gap distance, and fission chamber geometry) are described. Next, experiments designed to identify the location within the chambers where the PD are being generated are presented in way to propose changes to the fission chamber in order to reduce or eliminate the PD signal

Characterization and localization of partial-discharge-induced pulses in fission chambers designed for sodium-cooled fast reactors

During the operation of the Superphenix and Phenix reactors, an aberrant electrical signal was detected from the fission chambers used for neutron flux monitoring. This signal, thought to be due to partial electrical discharge (PD) is similar to the signal resulting from neutron interactions, and is generated in fission chambers at temperatures above 400 °C. This paper reports work on the characterization and localization of the source of this electrical signal in a High Temperature Fission Chamber (HTFC). The relation between the shape of the PD signal and various parameters (nature and pressure of the chamber filling gas, electrode gap distance, and fission chamber geometry) are first described. Next, experiments designed to identify the location within the chambers where the PD are being generated are presented. After verification and refinement of the results of these localization studies, it should be possible to propose changes to the fission chamber in order to reduce or eliminate the PD signal

Progress in the development of the neutron flux monitoring system of the French GEN-IV SFR: simulations and experimental validations

International audienceThe neutron flux monitoring system of the French GEN-IV sodium-cooled fast reactor will rely on high-temperature fission chambers installed in the reactor vessel and capable of operating over a wide-range neutron flux. The definition of such a system is presented and the technological solutions are justified with the use of simulation and experimental results