Coolant Mixing Phenomena Influencing Measurements of Core Coolant Temperature Rises

During Superphénix commissioning, specific tests, including interchanges of subassemblies, were conducted to check the performances of the core temperature surveillance system. Temperature fluctuations, presumed to result from the mixing of the outlet plumes and the interaction with recirculating vortices in the upper plenum, were recorded. The results are compared with tests performed in different water mock-ups.