Deteriorated Heat Transfer Influence on the Stress–Strain State of Small Modular Reactors SCWR Fuel Bundles

Abstract

The analysis of deteriorated heat transfer (DHT) influence on the stress–strain state of a perspective core of small modular reactors with supercritical water (SMR SCWR) fuel assemblies is carried out based on experimental and numerical data. Experimental data for 3- and 7-rod assemblies of 600 mm height with twisting spacer screws, on which deterioration heat transfer regimes were observed. The analysis of the stress–strain state was performed for two cases of temperature field. In the first variant, the temperature field is estimated using computational fluid dynamics (CFD) with low-Re-effects accounting, which allows obtaining the maximum temperature, but incorrectly estimates the axial profile. In the second case, an experimental profile with an averaged tangential temperature value is considered. Strength analysis is performed using the developed numerical-analytical mechanical model of the rod assembly. Obtained results make it possible to establish what is more important for assessing the safety of perspective reactors: a conservative estimate of the maximum wall temperature or its local distribution.