ALEPH2 – A Monte Carlo burn-up code

Main developer: A. Stankovskiy
Developers: L. Fiorito, G. Van den Eynde
ALEPH is based on a coupling between a stochastic neutronic analysis code and a deterministic time-dependent isotopic evolution code.


In its current version, ALEPH2, the code capabilities have been extended to problems where different sources of radiation are present. ALEPH2 has been optimized in particular for:

  • Burn-up calculations for different types of reactor cores
  • Calculation of structural material activation
  • Source term calculations for any system containing radioactive material
  • Calculation of activation by spallation neutrons (with applications in Accelerator Driven Systems)
  • Analysis of shielding for transport and storage of radioactive waste and radiotherapy installations.

ALEPH works with any modern version of the MCNP/MCNPX family.

Major advantages

  • Nuclear data consistency: the same nuclear data is used for the static calculation (to obtain particle fluxes and spectra) as for the time-dependent evolution calculation. The nuclear data libraries in the ALEPH2 package are available at different nuclide temperatures (for neutron induced reactions) and for different particles (neutrons, protons, photons, alpha particles) based on currently available master libraries like ENDF/B-VII.1, JEFF-3.1.2,  JENDL-4.0 and TENDL-2012. Each library is complemented with nuclear data from the same master library for fission product yields, radioactive decay constants and spontaneous fission data.
  • Ease of use: the user has only one input file to maintain namely the original MCNP/MCNPX input file with some extra, ALEPH specific, input cards. Typically the user has to indicate which materials should be considered for isotopic evolution, the irradiation history, the cooling down history, … Once launched, the chain of calculations (static calculation to obtain particle fluxes and spectra, evolution of isotopes, update of the materials) is done automatically by the code. A calculation that was stopped can be restarted from the last irradiation step.
  • Output of one-group cross sections: at each irradiation step, ALEPH2 will generate a set of one-group (spectrum averaged) cross sections. These are made available to the user and can be used for other means (simple back-of-the-envelope calculations).
  • Applicable for Accelerator Driven Systems: ALEPH is one of few codes that can work in "fixed source mode" and not only in critical mode. This makes it the obvious choice for the analysis of Accelerator Driven Systems and particle accelerators in general.
  • Stable and precise solving routine for the evolution equations: ALEPH2 uses a solver of type RADAU5, an implicit Runge-Kutta scheme. This guarantees a very accurate solution to the stiff evolution equations. Excellent stability and precision of the results have been shown.