Assessment of high-temperature reactor fuel performance under accident conditions

The operational safety of nuclear power plants remains among the main issues affecting the acceptance of nuclear power in the public eye. Gas-cooled hightemperaturereactors (HTR) feature the remarkable property of being inherently safe against power excursions even under adverse conditions. With a combination of low power density, high thermal mass and high surface-to-power ratio, the core of an HTR can withstand certain accident scenarios without significant mechanical failure and release of fission products. The spherical or prismatic HTR fuel elements are a major component which influences the reactor performance in such accident conditions. Inside the graphite fuel elements, fissile material is contained in the form of thousands of small spheres of fuel enclosed in several coating layers (≈ 1 mm diameter). Modern HTR fuel contains TRISO (tri-structural isotropic) coated particles (CP) covered with a porous carbon buffer layer, two layers of pyrolytic carbon and a layer of ceramic silicon carbide. Together, the coatings provide a barrier against the release of gaseous and volatile fission products both in normal operation and under offnormal conditions.

KELLERBAUER Alban;  BOTTOMLEY Paul;  FREIS Daniel;  RONDINELLA Vincenzo;  VAN UFFELEN Paul; 

2011-10-07

Deutsches Atomforum / Kerntechnische Gesellschaft

JRC60682

https://publications.jrc.ec.europa.eu/repository/handle/JRC60682,