The Computer Code ATHLET

ATHLET-calculated reactor components (Source: GRS)

The thermal-hydraulic system code ATHLET (Analysis of THermal-hydraulics of LEaks and Transients) is being developed by GRS for the analysis of the whole spectrum of leaks and transients in PWRs and BWRs. The code is applicable for western reactor designs as well as for Russian VVER and RBMK reactors. The main code features are

  • advanced thermal-hydraulics,
  • modular code architecture,
  • separation between physical models and numerical methods,
  • pre- and post-processing tools,
  • portability to the prevalent computer platforms.

ATHLET is composed of several basic modules for the simulation of the different phenomena involved in the operation of a light water reactor:

  • thermo-fluiddynamics (TFD)
  • heat transfer and heat conduction (HECU)
  • neutron kinetics (NEUKIN)
  • and control and balance-of-plant (GCSM)

Further Information can be found in ATHLET Overview.

Validation of ATHLET
A comprehensive validation work has been performed in parallel to the ATHLET code development. A large number of experiments conducted worldwide in the field of nuclear reactor safety, which investigate the relevant thermal-hydraulic phenomena, have been simulated with ATHLET, and the results have been compared with measured data. The selection of the experiments is based on the CSNI Validation Matrix set up for reactor safety computer codes for the analysis of loss of coolant accidents and transients in NPPs. The analyses comprise single effects tests and integral tests as well as transients and incidents in real NPPs. The ATHLET validation strategy as well as a compilation of the performed analyses can be found in the ATHLET Validation Report.