Pin-Scale Code Development

Development of BISON for the engineering-scale simulation of nuclear fuel performance continued. Enhancements during this quarter include implementation of a nonlinear material model for Zircaloy cladding that simultaneously combines the phenomena of plasticity, thermal creep, and irradiation creep; implementation of a complete set of material properties and a creep model for stainless steel cladding; and modification of the coolant subchannel model to better support simulations of loss-of-coolant accidents.

BISON simulations are being compared to relevant empirical fuel pin data from the FRAPCON light water reactor (LWR) fuels database, with assistance from members of the Early Users Program. More than a dozen FRAPCON cases are being assessed using BISON. Although BISON development for use in predicting LWR fuel performance is still ongoing, assessments continue to show BISON capable of generally good agreement with experimental data for many of the major fuel performance parameters, such as peak fuel temperature, fission gas release, and cladding deformation. The first BISON training workshop was held for code developers and early users at INL on May 30-31. [ANL, INL, LANL]