High-fidelity multi-physics system TORT-TD/CTF/FRAPTRAN for light water reactor analysis

A need exists in the nuclear industry for higher-fidelity tools for light water reactor (LWR) analysis, due to increasing core heterogeneity and higher burnup of fuels. In order to address this need, a high-fidelity multi-physics (HFMP) system has been developed at the Pennsylvania State University (PSU). It consists of three codes - CTF for thermal hydraulics, TORT-TD for neutron kinetics, and FRAPTRAN for fuel performance. FRAPCON, which is applied to long-term steady-state fuel performance, is left separate and not modified, but is relevant to the system because it generates the initial conditions used in FRAPTRAN. These codes have been combined into a system in which they are coupled by means of serial integration. FRAPTRAN is the latest addition to the system while the initial coupling of TORT-TD and CTF was verified in different applications. Recent efforts have been directed at the design of an object-oriented system of interfaces for the coupled codes, by which the main program may control them in terms of high-level functionality. Further modifications to the system include the ability to use coolant-centered rather than fuel-centered channels, and the ability for TORT-TD to use a time step size that differs from that of CTF. The obtained results verify this new coupling, as well as demonstrate the advantages of using a fuel-performance code for modeling fuel rod feedback.