HTGR Knowledge Base

Conference Article: Radiation effect on the graphite of HTGR

Platonov, P.A.; Strombach, Ya.I.; Karpukhin, V.I.; Gurovich, B.A.; Chugunov, O.K.; Trofimchuk, E.I. (Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Atomnoj Ehnergii)

Abstract

For predicting the operability of graphite structures for modern nuclear installations, it is necessary to know the rules of radiation-induced changes in such properties of graphite as stability of dimensions, strength, creep, modulus of elasticity, coefficient of thermal expansion, heat conductivity and resistance to oxidation in a wide temperature range and at fast neutron fluence more than 1022/cm2. The dimensional change of graphite under irradiation is the most important parameter which determines the operability of HTGR graphite structures. The effect of irradiation on the thermophysical and mechanical properties of graphite is reported. The change of microstructure of graphite was also studied. One of the effective methods enabling to avoid cracking in nuclear graphite under irradiation is the production of the nuclear graphite with the difference of crystal grain size as small as possible. At low irradiation temperature, the change of crystal grain size occurs to a certain limit due to the change of the crystal lattice caused by radiation defects. At high irradiation temperature, the lattice parameters change less, and above 500 deg C, the change is negligible. Nuclear polycrystalline graphite changes complicatedly its dimensions due to porosity. One of the most important properties of stressed and strained graphite is the radiation creep.

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key words: deformation; graphite; high temperature; htgr type reactors; length; mechanical properties; neutron beams; physical properties; physical radiation effects; reactor materials; temperature dependence; beams; carbon; gas cooled reactors; graphite moderated reactors; particle beams; radiation effects
Reference:
Specialists' meeting on graphite component structural design, JAERI Tokai (Japan), September 8-11, 1986
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--11, pp:201-206