DEVELOPMENT OF A TRICARBIDE FOAM FUEL MATRIX FOR NUCLEAR PROPULSION

摘要

Under an NASA STTR project funded through Marshall Space Flight Center, a team from Ultramet Inc., Sandia National Laboratories and the University of Florida has been developing a new high temperature, tricarbide fuel matrix consisting of ZrC, NbC and UC using an open-cell reticulated foam skeleton. The new fuel is envisioned for use in nuclear thermal propulsion systems, bi-modal reactors and terrestrial high temperature gas reactors and builds on the tricarbide fuel research in the former Soviet Union. The new fuel is mechanically robust and very efficient given its extremely high surface area, higher melting point, minimal thermal stresses, and much reduced pressure drop compared to conventional fuel types. The matrix is anticipated to operate at temperatures as high as 3000K with minimal hydrogen erosion. The foam is an engineered material in which the porosity, size and thermal conductivity of the ligaments can be controlled independently to meet specific requirements. In this article we review the vapor phase alloying of the tricarbide to produce a homogeneous solid mixture of the constituents using TaC as a UC surrogate with the option of additional diffusion barrier layers as required. A credible reactor design and results of a new MP-CFD modeling capability using detailed simulation of the porous media are presented. Our near-term plans for UC integration and hydrogen testing at the University of Florida and future possibilities for continued development and testing are summarized.