Implementation of A Gibbs Energy Minimizer In A Fission-Product Release Computer Program

Abstract

Article InfoKeywords: Modelling of fission-product release from nuclear fuel; Gibbs energy minimization; Lanthanide release from urania fuel; Fission-product

Thermodynamically Informed Nuclear Fuel Codes—A Review and Perspectives

“…This improved database was later used in a prototypic version of SOURCE by Barber [84] via direct coupling between SOURCE and the commercial thermodynamic software CHEMAPP [19]. As a result of this improved representation of nuclear fuel thermodynamics, the fractional fission gas release predicted by SOURCE was in closer agreement to experimental measurements [84] compared to the previous thermodynamic assessment from Corse [85]. While reassuring, this is not surprising given the great improvements in the thermodynamic treatment of the fuel.…”

“…A common challenge experienced with coupling a nuclear fuel code with a thermodynamics code is the increase in computational expense, particularly when solved on a FEA mesh. This issue has not been reported in the open literature among Class II SA codes; in fact, Barber reported that the increased computational expense with coupling ChemApp with SOURCE was quite acceptable [84]. The reason why the computational increase with code coupling is more problematic with FEA codes is simply because of the very large number of thermodynamic calls associated with a large number of finite elements in space and steps in time.…”

“…Fission product transport is simulated within the fuel in a manner akin to most fuel performance codes (i.e., intergranular and intragranular diffusion) to predict the fission product inventory in the fuel-clad gap. While most fuel performance codes limit fission product transport to the gap, which is appropriate under NOC conditions, SOURCE includes models for fission product vaporization from the fuel surface following cladding failure [84]. This is handled in all production versions of SOURCE via a set of look-up tables that were derived from a series of thermodynamic calculations by Corse [85] and Lewis et al [86].…”

“…While reassuring, this is not surprising given the great improvements in the thermodynamic treatment of the fuel. Another important finding from the work of Barber was that the direct coupling of CHEMAPP to SOURCE added an acceptable increase in computational expense that remained tractable [84].…”

“…These pros and cons are similar to what was discussed earlier with Finite Element Analysis (FEA) based codes, notwithstanding the issue of computational expense is much greater with FEA codes compared to SA codes due to the much greater number of executions required. For example, Barber reported that the additional computation expense with coupling CHEMAPP with SOURCE was quite acceptable [84].…”