Thermal hydraulic performance assessment of dual-cooled annular nuclear fuel for OPR-1000

An internally and externally cooled annular fuel was proposed for an advance PWR, which can endure substantial power uprating. KAERI is pursuing the development for a reloading of power uprated annular fuel for the operating PWR reactors of OPR-1000. In this paper, the characteristics and verification of the MATRA-AF are described. The thermal hydraulic performance of a 12 × 12 annular fuel is calculated for the major design parameters and its performance is compared against the reference 16 × 16 cylindrical fuel assembly. In particular, the enhancements of the thermal hydraulic performance of dual-cooled annular fuel are estimated for the 100% normal power reactor core. The purpose of this study is to estimate a normal power for OPR-1000 with dual-cooled annular fuel, and ultimately to assess the feasibility of 120% core power. The parametric study was carried out for the fuel rod dimension, gap conductance, thermal diffusion coefficients, and pressure loss of the spacer grids. As a result of the analysis on the nominal power, annular fuel showed a sufficient margin available on DNB and fuel pellet temperature relative to cylindrical fuel. The margin amount seems accommodating a 20% power-uprate seems viable.

► A thermal hydraulic performance of a 12 × 12 annular fuel array is evaluated.
► The subchannel analysis code for the dual-cooled annular fuel, MATRA-AF is validated.
► We evaluate the sensitivity for geometry tolerances and operating parameter.
► We decide the essential design parameters to uprate the power generation by dual-cooled annular fuel.
► A thermal margin amount accommodating a 20% power-uprate seems viable.