Experimental validation of channel bowing effects on pin power distributions in a Westinghouse SVEA-96+ assembly

Effects of channel bowing on the pin power and 238U capture rate distributions have been studied experimentally and analytically in a test zone consisting of 9 full-size Westinghouse Atom SVEA-96+ fuel assemblies in the PRO-TEUS critical facility. A very significant bowing was simulated by displacing the central test assembly by 9 mm in the two horizontal directions from its centred position in the 33 assemblies array. Calculations were performed for a whole-reactor model using the HELIOS and BOXER codes and for a reflected assembly using CASMO-4. The agreement between calculated and measured reaction rate distributions in this configuration is found to be of a quality similar to that for the case with the central assembly in its nominal position. The direct comparison of measured and calculated effects of the central assembly displacement on the reaction rate distributions (based on the results obtained in the two different LWR-PROTEUS configurations) confirms that, for a well-characterized displacement, the codes are capable of predicting the changes with high accuracy. Atomic Energy Society of Japan.