PHYSOR 2016
The Westinghouse AP1000 PWR features an advanced first core with radial and axial heterogeneities which provides significant enhancements compared to traditional first cores, allowing best fuel usage and short transition to the equilibrium cycle with subsequent fuel reloads. These advanced features can pose some challenges to the core physics tools. In particular, the axial heterogeneity can pose a significant challenge in the codes adopting direct whole core calculations through 2D/1D approach, like nTRACER. This paper describes the performance of nTRACER for the hot-zero-power core physics calculations of the AP1000 PWR, against Monte Carlo reference solutions. The comparison of global core parameters, such as critical boron concentration and rod worth, yields good agreement whereas that of axial power distributions shows a noticeable deterioration in some of the nTRACER results, as a result of the steep HZP axial gradients. Hot-full-power core calculations are performed only with nTRACER to examine the thermal-hydraulic and depletion calculation capabilities of it.
