Graphite is widely used as a major internal structural material in high temperature gas-cooled reactors (HTRs). In order to evaluate service lives of graphite components, both the fast neutrons and temperature distributions inside the reactor core are required as input data for the irradiation-induced stress analysis. Since the fast neutron distributions may vary along the vertical direction due to the movement of the control rods, the corresponding location of the maximum neutron fluence changes with different in-core temperature levels. In this paper, the effect of the in-core temperature on both the stresses of graphite components due to irradiation and the corresponding life evaluations are studied numerically. The associated constitutive law for the simulation of irradiated graphite covering properties, dimensional changes and creep is briefly reviewed. A FORTRAN code based on user subroutines of MSC.MARC is developed in INET in order to perform three-dimensional finite element analysis of irradiated behavior of the graphite components for the HTRs. A side reflector graphite model is established and analyzed under a prescribed fast neutron distribution and several temperature levels. The results of irradiation-induced stresses and failure probability of the side reflector are obtained and the impact of temperature levels is discussed.

Volume Subject Area:
Student Paper Competition
Topics:
Graphite, Temperature, Neutrons, Irradiation (Radiation exposure), Stress, Constitutive equations, Creep, Failure, Finite element analysis, Fluence (Radiation measurement), FORTRAN, Probability, Rods, Simulation, Stress analysis (Engineering), Temperature distribution, Very high temperature reactors
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Copyright © 2009
 by ASME
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