The Laputa code for lattice physics analyses

A new lattice physics code called Laputa is currently under development at Tsinghua University. Aiming at the neutronics design of typical LWRs and advanced reactors, both the recent and traditional methodologies are integrated in the code. Laputa is able to model 2D arbitrary geometries by means of the combinational-geometry approach that has been commonly used in Monte Carlo codes. The method of characteristics (MOC), with the CMFD acceleration and OpenMP parallelism technologies, is implemented as the transport solver. The newly-proposed embedded self-shielding method (ESSM) is realized in Laputa for resonance treatment. Besides, an advanced matrix exponential method is implemented for solving the Bateman equations in the depletion module. Numerical validations against Monte Carlo solutions demonstrate that Laputa is very promising for lattice physics analyses.