Institute for Neutron Physics and Reactor Technology (INR)

Neutronic / Thermal Hydraulic/ Thermo-mechanics Coupled codes Based on Nodal Diffusion Solvers

The first approach is to replace 1D parallel channel description of the core thermal hydraulics done with either internal TH-modules or system codes by the use of subchannel codes at fuel assembly level considering cross-flow between the neighbour assemblies.

KIT contribution to European simulation platform (NURESIM) for the multi-physical and multi-scale coupling of neutronic and thermal-hydraulic codes in the frame of NURISP and NURESAFE FP7 projects.  COBAYA3/SubChanFlow Coupling based on mesh superposition using the MED-Library of  theNURESIM Platform. Similar implementations are the coupling of DYN3D/SubChanFlow and CRONOS2/SubChanFlow.

PARCS/SubChanFlow is an internal fast running coupling developed at KIT for the direct prediction of safety parameters based on the PPR-method and an automatic SubChanFlow model generation at subchannel level after the nodal / fuel assembly simulation is performed. In this coupling approach, SubChanFlow is a module of PARCS.

PARCS/SubChanFlow/TRANSURANUS is a multiphysics coupling for the realistic core simulation taking into account the thermo-mechanic behaviour of irradiated fuel and the power history. It is implemented in a MPI-architecture, where TU is launched automatically as much times as many fuel assemblies exist in the core while PARCS/SubChanFlow is run in the main Master Processor. Both static core analysis of fresh and burnt core loading can be done at nodal level using a representative pin per fuel assembly for the thermo-mechanic analysis with TRANSURANUS.

TRANSURANUS is the in-house fuel performance code of JRC/ITU at Karlsruhe. The code predicts the physical status of the fuel at different fuel cycle stages. TRANSURANUS simulates the fuel behaviour using e.g. fuel manufacturing and operational data, reactor and fuel-cladding material properties data as well as operational history for both steady-state and transient simulations (RIA, LOCA, etc.).


  1. Joaquín R. Basualdo; Victor Sánchez-Espinoza, Robert Stieglitz, Rafael Macián-Juan; Integration of the subchannel thermal-hydraulic code SubChanFlow into the reactor dynamics code PARCS: Development and testing based on a computational benchmark. Progress in Nulear  Energy (2019 september) 103138.
  2. I. Spasov, S.Mitkov, N. P.Kolev; S. Sanchez-Cervera, N. Garcia-Herranz, A. Sabater, D. Cuervo; J. Jimenez, V. H. Sanchez; L.Vyskocil; Best-estimate simulation of a VVER MSLB core transient using NURESIM platform codes. Nuclear Engineering and Design (2017) 17 April 2017
  3. Bruno Chanaron, Carol Ahnert b, Nicolas Crouzet,  Victor Sanchez, Nikola Kolev, Olivier Marchan, Soeren Kliem , Angel Papukchiev;  Advanced multi-physics simulation for reactor safety in the framework of the NURESAFE project. Annals of Nuclear Energy 84 (2015) 166–177.
  4. M. Calleja, J. Jimenez, U. Imke, V. Sanchez, R. Stieglitz, José J. Herrero, R. Macián; Implementation of hybrid simulation schemes in COBAYA3/SUBCHANFLOW coupled codes for the efficient direct prediction of local safety parameters Annals of Nuclear Energy, Volume 70, August 2014, Pages 216-229.
  5. M. Calleja, V. Sanchez, J. Jimenez, U. Imke, R. Stieglitz, R. Macián ; Coupling of COBAYA3/SUBCHANFLOW inside the NURESIM platform and validation using selected benchmarks. Annals of Nuclear Energy, Volume 71, September 2014, Pages 145-158.
  6. M. Calleja, J. Jimenez, V. Sanchez, U. Imke, R. Stieglitz, R. Macián; Investigations of boron transport in a PWR core with COBAYA3/SUBCHANFLOW inside the NURESIM platform. Annals of Nuclear Energy, Volume 66, April 2014, Pages 74-84
  7. Armando Miguel Gomez-Torres, Victor Hugo Sanchez-Espinoza, Sören Kliem, Andre Gommlich; Implementation of a fast running full core pin power reconstruction method in DYN3D. NED 274 (2014)44-55.
  8. S. Kliem, A. Gommlich, A. Grahn, U. Rohde, J. Schütze, Th. Frank, A. Gomez, V. Sanchez: “Development of multi-physics code systems based on the reactor dynamics code DYN3D”, Kerntechnik 765/3 pp. 160-165 (2011)