APOLLO II: A User-Oriented, Portable, Modular Code for Multigroup Transport Assembly Calculations

Apollo2 Year 2010

“…The latter are obtained by solving a simplified elastic slowingdown equation, called heterogeneous fine structure equation, [32] written for one resonant isotope diluted in non resonant ones. Space-dependent interference effects are directly incorporated via the use of a full collision probability description with no need for geometricallydependent Dancoff factors.…”

“…The fine-group calculation was done with the 172-group (80 thermal) XMAS library with a fast interface-current 'multicell' UP1 flux solver where cell exchanges account for the different positions of the daughter cells in the assembly. [32] The auxiliary cellhomogenized assembly calculation was done with the IDT short-characteristics module of APOLLO2 with 40 macrogroups (25 thermal) and 16 16 cells, while the 16-macrogroup (13 thermal) detailed heterogeneousassembly calculation was done with the method of (long) characteristics (MOC) of the TDT module with 3784 regions. [48], [4] Self-shielded cross sections accounting for isotopic mixture and spatial interactions are computed in 1D cylindrical geometry for each cell type.…”

“…The general characteristics of the first version of the code were presented twenty two years ago [32] and an update was published twelve years latter. [33] In the meantime a large number of publications and presentations in international meetings have illustrated example applications and the new methodologies incorporated in the code.…”

“…Moreover, the code can treat stochastic dispersions of grains in homogeneous matrices by the double heterogeneity technique for both the collision probability method [43,44] and the method of long characteristics, [45,46] and has the capability to carry out leakage calculations for mutually interacting assemblies. [32] APOLLO2 flux solvers are based either on the collision probability method (CPM) -full CPM, interface-current techniques (ICT) [47] and simplified ICT (multicell methods) [32] -or on different spatial discretizations of the discrete ordinates form of the transport equation comprising finite differences, transversenodal and short and long characteristics (MOC) methods. [48,4] With the exception of the integro-differential transport (IDT) module, [48] which has three-dimensional capabilities, all APOLLO2 solvers cover the one-and twodimensional geometries.…”

HPC Challenges for Deterministic Neutronics Simulations Using APOLLO3® Code

“…Up to now, CEA, with EDF and AREVA support, is renewing its main application codes (deterministic codes "APOLLO2, CRONOS2, and ERANOS2", [1][2][3][4][5][6] Monte Carlo code TRIPOLI-4™, 7) depletion and fuel cycle MENDEL, successor of DARWIN code, 9) its nuclear data processing system GALILEE, 8) in order to have a complete and advanced nuclear modeling system (see Fig. 1) and CONRAD, 10) a nuclear reaction analysis tool in order to create evaluations.…”