Evolution of defects in micropellet fuel during the fabrication of HTGR compacts

The stress distribution arising in micropellets and cylindrical fuel compacts during fabrication, the stress concentration in micropellets located near the surface of a compact, and the evolution of defects in micropellets as a function of the type of stress state are investigated. It has been found that an ensemble of micropellets with a large number of particles contains a continuous spectrum of defects in the range 10^sup -4^-10^sup 2^ µm. Mechanical stresses engender evolution of the defects according to the scheme accumulation of microdefects [arrow right] microcracks [arrow right] cracks [arrow right] through defects. Recommendations are formulated for lowering the number of defects in micropellets during deposition of coatings on the micropellets and compaction.[PUBLICATION ABSTRACT]