Abstract-CABRI is an experimental pulse reactor operated by CEA at the Cadarache research center and funded by the French Nuclear Safety and Radioprotection Institute (IRSN).For the purpose of the CABRI International Program (CIP), operated and managed by IRSN under an OECD/NEA framework it has been refurbished since 2003 to be able to provide experiments in prototypical PWR conditions (155 bar, 300 °C) in order to study the fuel behavior under Reactivity Initiated Accident (RIA) conditions. This paper first reminds the objectives of the power commissioning tests performed on the CABRI facility. The design and location of the neutron detectors monitoring the core power are also presented.Then it focuses on the different methodologies used to calibrate the detectors and check the consistency and co-linearity of the measurements.Finally, it presents the methods used to check the linearity of the neutron detectors up to the high power levels (~20 GW) reached during power transients. Some results obtained during the power tests campaign are also presented.
CABRI is an experimental pulse reactor operated by CEA at the Cadarache research center. Since 1978 the experimental programs have aimed at studying the fuel behavior under Reactivity Initiated Accident (RIA) conditions. Since 2003, it has been refurbished in order to be able to provide RIA and LOCA (Loss Of Coolant Accident) experiments in prototypical PWR conditions (155bar, 300°C). This project lied within a broader scope including an overall facility refurbishment and a safety review. The global modification is conducted by the CEA project team. It is funded by IRSN, which is conducting the CIP experimental program, in the framework of the OECD/NEA project CIP. It is financed in the framework of an international collaboration. During the reactor restart, commissioning tests are realized for all equipment, systems and circuits of the reactor. In particular neutronics and power commissioning tests will be performed respectively in 2015 and 2016. This paper focuses on the design of a complete and original dosimetry program that was built in support to the CABRI core characterization and to the power calibration. Each one of the above experimental goals will be fully described, as well as the target uncertainties and the forecasted experimental techniques and data treatment.
In a Pressurized Water Reactor (PWR), the rod ejection is a design basis accident for uncontrolled evolution of the nuclear reaction. In case of failure of a rod mechanism, the rod ejection is caused by the pressure differential between the primary loop (155 bar) and the confinement's enclosure (atmospheric pressure). It leads to a local power transient and a fast fuel temperature increase. The power transient is limited by the reactivity feedbacks before the automatic reactor shutdown. The CABRI experimental pulsed reactor is funded by the French Nuclear Safety and Radioprotection Institute (IRSN) and is operated by CEA at the Cadarache research center. It is designed to study fuel rods behavior under Reactivity Initiated Accident (RIA) conditions. The tested fuel rod is placed at the center of the CABRI core, inside a pressurized water loop reproducing PWR conditions. CABRI is a pool type reactor, made of 1487 UO 2 fuel rods and controlled by 6 Hafnium control rods. A specific device allows the fast depressurization of 3 He contained in 4 transient rods to reproduce control rods ejection conditions. Based on a BEPU approach, we developed a tool, named SPARTE, for CABRI power transients calculation. This tool is based on point kinetics, simplified thermal-hydraulics and thermal-mechanics. It computes the global behavior of the core by the calculation of a mean fuel rod. It includes models of reactivity insertion specific to the CABRI transient rods system, variable
The purpose of this paper is to provide a preliminary overview of the phenomena observed during the experimental phase of the PHEBUS Fission Product Test FPT3. This experiment was the last in the series of 5 in-pile integral experiments performed by IRSN in the PHEBUS facility operated by the CEA on the site of Cadarache. Unlike the previous tests, FPT3 used boron carbide as absorber material instead of silver-indium-cadmium, so varying an important parameter impacting physico-chemical phenomena. FPT3 test course was in agreement with the pre-defined test protocol, including a 8,5day irradiation phase, a fuel bundle degradation phase which lasted less than 5 hours and a 4-day long-term phase that consisted of an aerosol stage dedicated to the analysis of aerosol deposition mechanisms inside the containment vessel and a chemistry stage devoted to the analysis of the iodine chemistry. During the experiment, both the on-line instrumentation and the periodic samplings worked quite well. The fuel degradation progress could be analysed through both temperatures inside the bundle and gaseous concentration measurements performed in the circuit and inside the containment vessel. Some major events, like fuel clad and absorber rod failures or material relocations, were clearly correlated to both bundle and circuit instrumentation signals. The post test non destructive examinations of the fuel bundle (X-radiography, X-and γtomographies and γ-scanning) allowed to compare FPT2 and FPT3 bundle final degradation states. On-line γ−detector measurements coupled with numerous post test gamma-counted sequential samplings help for the characterization of the iodine behaviour inside the containment vessel during the degradation and the long term phases.The whole set of measurements appears self-consistent and provides new data for the iodine solubility inside the sump, the iodine gaseous fraction and the organic versus molecular iodine distribution inside the containment atmosphere.
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