The Pegasus code is a culmination of nuclear fuel behavior knowledge and experience that spans a period of over five decades. It is a total fuel-cycle simulation of fuel response from initial insertion in reactor to deposition in permanent storage. The goal of Pegasus is to treat, with equal fidelity, the modeling of fuel behavior during the active fuel cycle and the back-end cycle of spent-fuel storage and transportation in a single, self-consistent, and highly cost-effective analysis approach. In the active part of the fuel cycle, Pegasus’s superior three-dimensional thermo-mechanics, coupled with validated nuclear and material behavior models, and robust fuel-cladding interface treatment make it a high-fidelity predictor of fuel-rod response during flexible power operations and operational transients.
In the backend fuel cycle, Pegasus can perform analyses in a seamless transition from in-reactor to wet storage, to dry storage and eventually transportation under normal conditions and hypothetical-accident conditions of transport. The value of this Pegasus approach, which allows the analyst to combine fuel rod performance AND structural analysis into one seamless process, can best be appreciated by comparing it to the conventional time-consuming low-fidelity procedure of transferring output from fuel performance codes to structural analysis codes.