The Alchemist Code Download [BETTER]
Tristan Ridings
We present here the chemical model Alchemist, developed for the UK fuel pin modelling code TRAFIC. After a brief description of TRAFIC, we indicate how Alchemist calculates chemical equilibria for each TRAFIC finite element. Comparing results from a preliminary version of Alchemist with measurements from a pin at 12% burn-up indicates that a more sophisticated radial transport model is required. The modified model depends on diffusion coefficients for the various species involved and the morphology of the fuel. We discuss how the calculation of chemical equilibria can be incorporated into a fuel pin modelling code, and which physical processes are affected by the redistribution of fission products. A detailed chemical treatment must be the best way to understand the behaviour of fission products in the fuel-clad gap ("JOG") and to predict clad corrosion: two phenomena that take on increasing importance as fuel pins are taken to ever-higher burn-ups.