Gamma scan validation of the ARTEMIS BWR models

Framatome has recently developed a new BWR computational scheme relying on the APOLLO2-A lattice physics code together with the ARTEMIS core simulator. Some of the new developments in ARTEMIS that are specific to BWR include: enhanced cross section parametrization to handle spectral history effects, implementation of the two-fluid, three phase F-COBRA-TF code for full core steady-state and transient calculations, and pin-by-pin fission product nuclide density reconstruction. The latter model is built upon the pin power reconstruction, a.k.a. the dehomogenization model in ARTEMIS. This paper presents the validation of the new BWR models against gamma scan measurements made at the Oskarshamn2 reactor, for which modern BWR fuel assemblies with part length fuel rods such as ATRIUM 10 and Westinghouse SVEA96 Optima2, were gamma-scanned. Gamma scan is a non-destructive method to determine the relative fission product ¹⁴⁰Ba density in a nuclear fuel assembly, which is directly proportional to the fission densities in the core prior to the measurement. The measurements are done on a pin-by-pin basis, and on a full assembly basis. These measurements provide valuable information regarding the accuracy of the computational scheme of a LWR core physics simulator and its key outputs, such as the pin-by-pin and nodal powers. The analysis shows an excellent agreement for both the nodal and pin-by-pin ¹⁴⁰Ba concentrations between ARTEMIS and the measurements made at Oskarshamn2.