Scattering Reduction of the Double-Heterogeneity Treatment in Dragon

The double-heterogeneity treatment is available in many lattice codes to represent the effect of one or many stochastic media on the deterministic solution of the neutron transport equation. A stochastic medium is a mixture of a diluent matrix with cylindrical or spherical microstructures of different sizes. Different models have been presented in the past, some limited to the collision probability method and others limited to the method of characteristics. We have reformulated these existing models in a uniform framework and introduced a scattering reduction, making them compatible with any solution technique of the neutron transport equation. This new approach has been implemented in the Dragon Version4 lattice code in a generic way that is interoperable with the overall code features. This approach can easily be implemented within any existing code dedicated to the solution of the transport equation.