PRIME™ Advanced Fuel Features Package


Westinghouse’s PRIME™ advanced fuel features help to improve fuel performance, enhance fuel reliability, enable better fuel cycle economics and provide additional margin at uprated conditions and higher burnup. The package of features includes
an optimization of enhancements based on proven Westinghouse fuel reliability and world-class leader- ship in the design and manufacture of nuclear fuel. PRIME fuel features are available for the 17x17 Robust Fuel Assembly 2 (RFA-2), 17x17 Optimized Fuel Assembly (OFA) and 15x15 Upgrade Westing- house fuel designs.

Key Features

  • Low Tin ZIRLO™ mid grids and intermediate flow mixing grids
    • Based on unrivaled experience and performance of Westinghouse’s ZIRLO® grid material
  • Reinforced dashpot in guide thimble tubes
    • Incorporates a double tube design to further improve dimensional stability and stiffness in the lower portion of skeleton.
  • PRIME Bottom Nozzle
    • With the incorporation of a lower pressure drop adapter plate and an innovative debris filter side-skirt, the decreased flow resistance allows a higher proportion of flow through the fuel assembly while mitigating debris migration between fuel assemblies.


  • Advanced materials – Low Tin ZIRLO grids support higher burnup with lower corrosion, lower growth and improved grid-to-rod fretting margin
  • Structural stiffness for margin against fuel assembly distortion, particularly at higher burnups
  • Lower pressure drop to improve flow and enhance thermal margin
  • Industry-leading mitigation features that add multiple layers of defense against debris