Reactivity-initiated accident simulation to inform transient testing of candidate advanced cladding

Nicholas R. Brown, Aaron J. Wysocki, Kurt A. Terrani

    Research output: Chapter in Book/Report/Conference proceedingConference contribution


    Advanced cladding materials with potentially enhanced accident tolerance will yield different light-waterreactor performance and safety characteristics than the present zirconium (Zr)-based cladding alloys. These differences are due to different cladding material properties and responses to the transient, and to some extent, reactor physics, thermal, and hydraulic characteristics. Some of the differences in reactors physics characteristics will be driven by the fundamental properties (e.g., absorption in iron for an iron-based cladding) and others by design modifications necessitated by the candidate cladding materials (e.g., a larger fuel pellet to compensate for parasitic absorption). Potential changes in thermal hydraulic limits after transition from the current Zircaloy cladding to the advanced materials will also affect the transient response of the integral fuel. This paper leverages three-dimensional reactor-core-simulation capabilities to provide information on appropriate experimental test conditions for candidate advanced cladding materials in a control-rod-ejection event. These test conditions use three-dimensional nodal kinetics simulations of a reactivity-initiated accident (RIA) in a representative state-of-the-art pressurized water reactor with both nuclear-grade iron-chromium-aluminum (FeCrAl) and silicon-carbide (SiC-SiC)-based cladding materials. The effort yields boundary conditions for experimental mechanical tests, specifically peak cladding strain during the power pulse following the rod ejection. The impact of candidate cladding materials on the reactor kinetics behavior of RIA progression versus that of reference Zr cladding is predominantly due to differences in (1) fuel mass/volume/specific power density, (2) spectral effects due to parasitic neutron absorption, (3) control rod worth due to hardened (or softened) spectrum, and (4) initial conditions due to power peaking and neutron transport cross sections in the equilibrium cycle cores resulting from hardened (or softened) spectrum. This study shows minimal impact of SiC-SiC-based cladding configurations on the transient response versus reference Zircaloy cladding. However, the FeCrAl cladding response indicates similar energy deposition, but with significantly shorter pulses of higher magnitude. Therefore, the FeCrAl-based cases have a more rapid fuel thermal expansion rate, and the resultant pellet-cladding interaction occurs more rapidly.

    Original languageEnglish (US)
    Title of host publicationTop Fuel 2016
    Subtitle of host publicationLWR Fuels with Enhanced Safety and Performance
    PublisherAmerican Nuclear Society
    Number of pages15
    ISBN (Electronic)9780894487309
    StatePublished - 2016
    EventTop Fuel 2016: LWR Fuels with Enhanced Safety and Performance - Boise, United States
    Duration: Sep 11 2016Sep 15 2016

    Publication series

    NameTop Fuel 2016: LWR Fuels with Enhanced Safety and Performance


    OtherTop Fuel 2016: LWR Fuels with Enhanced Safety and Performance
    Country/TerritoryUnited States

    All Science Journal Classification (ASJC) codes

    • Fuel Technology
    • Nuclear Energy and Engineering


    Dive into the research topics of 'Reactivity-initiated accident simulation to inform transient testing of candidate advanced cladding'. Together they form a unique fingerprint.

    Cite this