ERANOS [1]  is  a  system  of  neutron  and  gamma  codes developed  within  a  European  framework. It comprises different modules that permits to design fast reactor core, to evaluate reactor shielding, and  to perform fuel cycle analyses. ERANOS is a deterministic code system: neutron calculations are done in two different steps: (1) at cell level, (2) at core level.



The cell package ECCO allows to perform rather precise calculations at cell level, the module has access to the nuclear data libraries (such as JEFF and ENDF/B). These processed nuclear data are then used to solve the neutron transport at core level.



ERANOS provides several neutron solvers, each of them discretize the transport equation with a different approach. For example, package BISTRO uses a finite difference method in space and a collocation method in angle (i.e. discrete ordinates method); package VARIANT uses instead a finite-element-like approach in both space and angle. One peculiarity of VARIANT is the possibility to solve the equation on an hexagonal lattice.

A further package (KIN3D) builds on the VARIANT module to allow time-dependent analyses for fast reactors: a fundamental aspect of fast reactor safety.

The module contains also several smaller modules and utilities to post-process data.


We have extended the ERANOS code at KIT. In particular, an extension allows VARIANT to use heterogeneous nodes (i.e. nodes in which material properties can vary spatially within the node itself). In some cases, this technique reduces the total number of nodes in the computations, making calculations faster (an important aspect especially for transient analyses).


Fig. 1. Power map computed with ERANOS





  1. G. Rimpault et al., The ERANOS code and data system for Fast Reactor neutronic analyses, Proc. Int. Conf. New Frontiers of Nuclear Technology: reactor physics, safety and high-performance computing (PHYSOR 2002), Seoul, Korea, October 7-10, 2002.