Research Needs for Uranium-Zirconium- Based Metallic Fuels

Abstract

The purpose of this report is to summarize the needs and present recommendations related to the future direction for U-Zr-based metallic fuel research (including binary U-Zr and ternary U-Pu-Zr alloys). These needs and recommendations were determined by subject matter experts from various institutions during a two-day workshop held at the University of Florida in November, 2019. During open-floor discussions, the highest priority gaps in our understanding of U-Zr-based fuels were down-selected, and near-and long-term needs that directly impact the implementation of these metallic fuels were identified. The identified near-term needs include investigation of the following phenomena: i) swelling and fission gas release, ii) fuel-cladding chemical interaction, iii) phase evolution/constituent redistribution, and iv) thermal properties of the fuels. The long-term needs are: i) investigation of fuel creep and plasticity and ii) fission product (lanthanide) transport. In addition, there was general agreement that all institutions and subject matter experts would benefit from an open-source metallic fuels database with thermophysical property and microstructural data, along with fuel operation/irradiation history, which should be regularly updated with vetted information from new experimental and computational investigations and used to advance metallic fuels research and development. Finally, we recommend that metallic fuel research should be ongoing and that fuel qualification and fuel optimization should be equally prioritized; research combining experiments with modeling and simulation has the largest potential impact.

Metallic Fuel Performance Code Requirements for the Versatile Test Reactor Project

“…These behaviors are responsible for fuel and cladding deformation and can influence changes in material properties such as thermal conductivities and elastic moduli. Each behavior is discussed in further detail below, and more in-depth reviews are available in the open literature [9], [34], [37], [38].…”

“…The ideal fuel performance code would include a full set of correlations and models for all fuel and cladding material properties and behaviors. Unfortunately, the technical complexity of developing such a code and the limited availability of fundamental property data for some fuel element materials make this task unrealistic at this time [38]. However, engineering judgement can be used to define minimum requirements and additional features as realistic and achievable goals for the near term while ensuring that codes provide useful predictions.…”