Thermal equivalence between nuclear fuel rod model and experimental heater simulator

Method of formulating nuclear fuel rod model (typical materials for pellet and clad, including usual gas-gap), which is thermally equivalent to multi-layer experimental heater simulator (any materials in contact, and/or without/with gas-gap) is presented. Thermally equivalent typical fuel rod model is defined. To validate it, the HECHAN model able to use different layouts of multi-layer rod/simulator geometry with constant and/or temperature dependent thermal–physical properties is used. Comparison with measured data for cladding surface temperatures in both pre- and post-CHF regimes proved applicability of this approach in transients. The rod model is easy to define, without changing the source of standard thermal–hydraulic code—only through input deck. It is qualified for further use in COBRA 3-CP and COBRA-TF codes for their validation on experiments using the particular heater simulator design.