Analysis and improvements of the DPN acceleration technique for the method of characteristics in unstructured meshes

Apollo2 Year 2010

“…[66] This technique extends the previous DP0 method by introducing a double P1 angular expansion for the angular fluxes entering and exiting the regions. A biconjugate gradient stabilized Krylov method [67] is used, together with algebraic pre-conditioners, [68] for the iterative solution of the DPN equations. Further speed up of the solution of the DPN equations has been obtained via a multi grid surface-response method based on a multidomain decomposition.…”

“…In close partnership with CEA, a methodology for industrial PWR, BWR applications based upon the MOC transport solver [4,88] and a multi-level scheme was setup by AREVA. This multi-step approach is an adaptation of the generic flux reconstruction methodology developed by CEA (see Section 5) to the specific needs of AREVA's computation scheme.…”

An Integral Multidomain DPN Operator as Acceleration Tool for the Method of Characteristics in Unstructured Meshes

“…The DP N acceleration equations are used as a low-order operator for the acceleration of the MOC. [7,8,9] The equations are obtained by the same projective technique that is used to derive the transport MOC equations but over different representation functions. We present here the transport MOC equations and in the next section the low-order DP N equations.…”

“…The DP N method, originally introduced by Sanchez and Chetaine [7], is the operator to be used in the framework of the synthetic acceleration procedure for TDT. Generalizations of this technique have been recently introduced in [8,9] to improve the physical approximations of the initial formulation and to speed up the solution procedure. Further improvements are presented here and results are shown to illustrate the speed up factors of the TDT code (which is currently used for industrial calculations as a flux solver of the APOLLO2 [1] code system).…”

HORUS3D/N Neutron Calculation Tool, a Deterministic Scheme Dedicated to JHR Design and Safety Studies

“…In the first step, for each kind of components present in the JHR, the 2D APOLLO2 lattice code, using fine energymeshing, provides libraries of self-shielded cross sections collapsed into 6 energy groups and tabulated versus burnup (or fluence). In the second step, these collapsed cross sections are introduced into a 3D full core calculation performed with the CRONOS2 diffusion code on a hexagonal spatial meshing, two reference routes for validation purposes:  a reference route for the JHR beginning of life core calculations (at time-step 0), based on 2D and 3D continuous-energy Monte Carlo TRIPOLI-4.9® computations [ 9 ], on heterogeneous geometry (see § III.C),  a deterministic reference route for the JHR core calculations during depletion, based on 2D APOLLO2.8-4-MOC computations [ 10 ], [ 11 ], on heterogeneous geometry (see § III.B).…”