This paper presents the recent improvements in the DeCART code for HTGR analysis. A new 190-group DeCART cross-section library based on ENDF/ was generated using the KAERI library processing system for HTGR. Two methods for the eigen-mode adjoint flux calculation were implemented. An azimuthal angle discretization method based on the Gaussian quadrature was implemented to reduce the error from the azimuthal angle discretization. | Improvement and verification of the DeCART code for HTGR core physics analysis Nuclear Engineering and Technology 51 (2019) 13e30 Contents lists available at ScienceDirect Nuclear Engineering and Technology journal homepage: Original Article Improvement and verification of the DeCART code for HTGR core physics analysis Jin Young Cho a, Tae Young Han a, Ho Jin Park a, Ser Gi Hong b, Hyun Chul Lee c, * a Korea Atomic Energy Research Institute, 111 Daedeok-daero 989-Beongil, Yuseong-gu, Daejeon, 34057, South Korea b Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 17104, South Korea c Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, South Korea a r t i c l e i n f o a b s t r a c t Article history: This paper presents the recent improvements in the DeCART code for HTGR analysis. A new 190-group Received 12 April 2018 DeCART cross-section library based on ENDF/ was generated using the KAERI library processing Received in revised form system for HTGR. Two methods for the eigen-mode adjoint flux calculation were implemented. An 2 August 2018 azimuthal angle discretization method based on the Gaussian quadrature was implemented to reduce Accepted 4 September 2018 Available online 7 September 2018 the error from the azimuthal angle discretization. A two-level parallelization using MPI and OpenMP was adopted for massive parallel computations. A quadratic depletion solver was implemented to reduce the error involved in the Gd depletion. A module to generate equivalent group constants was implemented Keywords: DeCART for the nodal codes. The capabilities of the DeCART code were improved for geometry handling including HTGR an approximate treatment of a cylindrical outer boundary, an explicit border model, the R-G-B checker- Adjoint solver board model, and a super-cell model for a hexagonal geometry. The newly .