Nuclear fuel pellet embedded with a thermally conductive insert in the form of branching arms distributed from a hollowed-out inner cylinder towards the outside of the pellet

The nuclear fuel pellet with a thermal conductive insert featuring branched branches addresses the issues of low thermal conductivity and gaseous swelling, achieving substantial temperature reduction and improved safety through enhanced heat evacuation and athermal gas diffusion, thus improving reactor performance and safety.

WO2025003408A1PCT designated stage expired Publication Date: 2025-01-02COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
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Patent Information

Application Number
PCT/EP2024/068258
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2023-06-29
Filing Date
2024-06-28
Publication Date
2025-01-02

AI Technical Summary

Technical Problem

Nuclear fuel pellets in Fast Neutron Reactors face challenges with low thermal conductivity and gaseous swelling, leading to high core temperatures and potential fuel melting or cladding rupture during power transients, which existing designs fail to adequately address while maintaining mechanical strength and manufacturability.

Method used

A nuclear fuel pellet design incorporating a thermal conductive insert with branched branches extending from a hollowed-out interior cylinder to the exterior, made of materials like molybdenum or niobium alloys, which significantly enhances thermal conductivity and reduces gaseous swelling by promoting heat evacuation and athermal diffusion of fission gases.

Benefits of technology

The design reduces the maximum fuel temperature by several hundred degrees Celsius, improves thermal performance by 20 to 30 times, and enhances safety margins by reducing thermal expansion and mechanical interaction with the cladding, thereby increasing operating flexibility and burn-up capacity.

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Abstract

The invention relates to a nuclear fuel pellet (6) embedded with a thermally conductive insert (7) in the form of branching arms (7.1 to 7.6) distributed from a hollowed-out inner cylinder (61) towards the outside of the pellet. The invention essentially consists of a nuclear fuel pellet (6) embedded with, within a straight cylindrical ring (60) of fissile material, a thermal conductor (7), in particular a metal conductor, in the form of main branching arms (7.1 to 7.6) that extend from the inside of the ring (60) to the outside and are advantageously distributed homogeneously within the ring. The insert made up of its macrostructure arms and branches makes it possible to reduce the maximum temperature of the fuel by several hundreds of degrees Celsius according to its dimensions, its constituent material and the distribution of its arms in the straight cylindrical fuel ring (60).
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Citation Information

Patent Citations

  • Nuclear fuel pellet comprising a heat-conducting metal or metal alloy insert having a cross-shaped cross section, associated nuclear fuel rod and fuel bundle, use in a pressurized water reactor (PWR)

    WO2022223387A1

  • Nuclear fuel pellet comprising a heat-conducting metal or metal alloy insert having solid disks or disks with a hole along the central axis

    WO2022223504A1

  • Nuclear fuel pellet incorporating an insert made of metal or a thermally conductive metal alloy with solid discs and solid shaft connecting the discs along the central axis, associated nuclear fuel rod and assembly, and use in pressurised water reactor (PWR)

    WO2022223510A1

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    US20140185731A1