Experimental and computational thermalhydraulics research related to CANDU reactor operation and safety

This paper describes recent, ongoing and planned research projects at the University of Ottawa, whose objective is to enhance our knowledge of flow and heat transfer in CANDU rod bundles and header/feeder systems and to assist the Canadian nuclear industry in the analysis of operation and safety of CANDU components as well as in designing improved ones. Several experimental facilities are being developed, including a refractive-index matching flow loop for detailed measurements of flows in eccentric annuli and rod bundles, a large-scale, heated rod-bundle facility with air as medium, matching the Reynolds number of the CANDU core and suitable for the study of the effects of geometrical distortions (e.g., pressure tube creep, spacers and fuel element bow) and transients, and an air-water loop for the testing of the operation of wire-mesh sensors and the study of two-phase flows in simple header/feeder vessels. Extensive CFD work on similar topics is also been conducted in parallel with the experiments using the experimental results for its validation. (author)