Many computer programs used for fuel design and licensing calculations are fuel or reactor vendor owned codes, which are not available for general use. These are not considered further here. The remaining, more generally available, codes are discussed further below.

Lattice codes commonly used for LWR applications include CASMO and WIMS. For fast reactor applications, ECCO is most often utilised (at least in Europe). The corresponding whole core neutronics codes are SIMULATE, PANTHER and ERANOS, respectively. Of the Monte Carlo codes, MCNP is the most widely used.

With respect to LWR applications: system thermal-hydraulic codes commonly used include RELAP and RETRAN; the most commonly used core thermal- hydraulics code is VIPRE. With respect to fast reactor applications, the choice is more varied — a selection of core thermal-hydraulics codes used for liquid-metal cooled fast reactor applications can be found in the proceedings of an IAEA technical committee meeting held in Obninsk, Russia, in 1998 (IAEA, 2000b).

Fuel performance codes commonly used for LWR applications include TRANSURANUS, ENIGMA, FEMAXI and FRAPCON (steady-state)/ FRAPTRAN (transient). A fuller list of codes used for water-cooled reactor applications can be compiled from the codes utilised in IAEA’s FUMEX-III co-ordinated research project (Killeen et al., 2009). For fast reactor applications, TRAFIC is the standard code used in the UK; other codes are utilised elsewhere.