CABRI Experimental Reactor: Experimental Reassessment of CABRI Core Power and Measurement Uncertainties

The CABRI experimental reactor operated by CEA is located at the Cadarache research centre, in southern France. The common objective of the programmes that have been conducted on CABRI since 1978 is the study of fuel rod behaviour under Reactivity Initiated Accident (RIA) conditions. The CABRI experimental reactor includes an experimental loop specially designed to position in the centre of the driver core the instrumented test device housing the fuel pin to be tested, and to cool the tested fuel rod into the required thermohydraulic conditions. Initially designed for safety studies on FBR's fuels the experimental loop was a sodium loop. In view of the burn-up increase of PWR's fuels (optimization of PWR core management) the facility was modified in order to have a water loop able to provide thermohydraulic conditions representative of the nominal operating PWR's ones (155 bar, 300 .deg. C). This programme which began in 2003 lied within a broader scope including an overall facility refurbishment and a safety review. In this framework, an experimental method was defined to assess the power of the CABRI core, and thus, the injected energy in the experimental fuel rod. In particular, this method will take into account the ingress of pool water into the newly designed upper water box during thermal balances performed on the core water cooling circuit (calibration phase of the neutron power chambers). Uncertainties of about 4 % and 11 % are expected respectively on the core power measurement and on the injected energy in the tested fuel rod