NECP-Hydra is a high-performance discrete ordinates transport code based on the KBA parallel algorithm. NECP-Hydra is suitable for critical, shielding and sub-critical calculations in X-Y-Z and R-θ-Z geometries. NECP-Hydra adopts a multi-angle scanning algorithm based on the KBA parallel algorithm, which improves the parallel efficiency of the KBA algorithm. Parallel efficiency can reach 50% using 10,000 processors on the Tianhe II server. The GMRES and Mesh-Corner DSA algorithm are used to improve the calculation speed of NECP-Hydra. Based on the one-group GMRES algorithm, we develope the multi-group GMRES algorithm, which has increased the number of available CPUs for the KBA algorithm by an order of magnitude. Currently, the main functional modules of NECP-Hydra include surface source continuation calculations, quadrature sets with energy change, geometric modelling visualization, dose rate output, angular flux output, higher order flux moment output, and merging groups and regions, etc. Hydra consists of Hydra_Cross, Hydra_Solver, Hydra_View and GGTM2Hydra. As shown in the following figure.

We built a pressurized water reactor plant shielding calculation model using NECP-Hydra, adopting bugle96 database, for the neutron and photon shielding calculation. The grid scale was 130 million, the discrete angle order was S16 and the scattering source expansion order was P3. It only used 1240 CPUs and took 1 h to perform shielding calculation on the Tianhe II server. The plant model and the first group flux distribution are shown in the following figures.