Contact

Dr. Sören Kliem

Head
Reactor Safety
s.kliemAthzdr.de
Phone: +49 351 260 2318

Department of Reactor Safety


Research

Neutron physics and reactor dynamics


  • Validation and application to light water reactors and innovative reactor concepts of the Monte Carlo code SERPENT2
  • Application of the deterministic lattice code HELIOS-2
  • Development, verification and application of the in-house reactor dynamics code DYN3D
  • Extension of the DYN3D code to innovative reactor concepts
  • Coupling of DYN3D to the system code ATHLET
  • Coupling of DYN3D to the Computational Fluid Dynamics codes ANSYS CFX and TRIO_U

Plant dynamics and severe accident analysis

  • Accident analysis and analysis of plant dynamics using the ATHLET system code
  • Assessment of the impact of severe accident management measures on the progression of severe accidents in PWRs and VVERs

Monte-Carlo simulations (n- / γ-field calculations)


  • Development of the in house Monte Carlo code TRAMO
  • Fluence calculations of the of the reactor pressure vessel and internals using MCNP and TRAMO
 


Latest publication

Extension and verification of multi-group JFNK-generated uniform discontinuity factors for nodal diffusion applications

Smith, J.; Painter, B.; Fridman, E.; Kotlyar, D.

Abstract

Monte Carlo (MC) codes can be computationally expensive for core neutronics analyses and prohibitive in transient simulations. MC codes can also be used to generate few-group homogenized constants. These are then used by nodal diffusion codes, which offer time-efficient few-group nodal solutions. To ensure that the MC solution is reproduced by the diffusion solver, reference discontinuity factors (DFs) are required. This paper uses the Jacobian-Free Newton Krylov (JFNK) iterative scheme to generate the few-group DF values. The primary objective is to verify the JFNK-generated DFs against the nodal expansion method (NEM) semi-analytical solution. Multiple verification cases, ranging from a 1D multi-nodal problem to a 2D small modular reactor (SMR) core, are used to compare the DFs values and the corresponding flux solutions. The homogenous flux solutions obtained by the nodal diffusion code, DYN3D, yield near perfect agreement with the reference power profiles only when complemented by the generated correction DFs.

Keywords: Nodal Diffusion; Equivalence Theory; Jacobian-Free Newton Krylov; Monte-Carlo; Nodal Expansion Method

Related publications

Downloads

  • Secondary publication expected from 10.06.2026

Permalink: https://www.hzdr.de/publications/Publ-39496


More publications


Team


Head

NameBld./Office+49 351 260Email
Dr. Sören Kliem250/1082318
s.kliemAthzdr.de

Employees

NameBld./Office+49 351 260Email
Dr. Yurii Bilodid250/2092020
y.bilodidAthzdr.de
Dr. Emil Fridman250/2092167
e.fridmanAthzdr.de
Jörg Konheiser250/1092416
j.konheiserAthzdr.de
Kerstin Kurde250/1073025
k.kurdeAthzdr.de
Dr. Evgeny Nikitin250/2072906
e.nikitinAthzdr.de
Dr. Frank Schäfer250/1172069
f.schaeferAthzdr.de