Fuel Element Mixing Promoter Evaluation Using a Thermal Tracing Technique

A new thermal tracing technique for the direct measurement of enthalpy mixing between coupled subchannels was used for the performance measurement of different mixing promoters used in nuclear fuel elements (FEs). This new technique allows direct enthalpy mixing measurements through the use of small thermal traces generated by means of a sophisticated superficial heater developed together with a high precision thermometry system. The results show the feasibility of this technique to the direct measurement of interchannel mixing parameter required for numerical codes that are usually employed to study the thermo-hydraulic behavior of new fuel elements designs. In the present work the technique is applied to the quantitative study of the performance of mixing vanes for a compact bundle of rods in completely turbulent flow using water as fluid at ambient conditions. Due to its simplicity this method seems feasible to be a useful fuel element design tool. The experimental results shown asymmetric behaviors not previously reported.