Laser system for boring and sampling in coated-particle fuel

A pulsed four-level solid-state laser (Nd/sup 3+/:yttrium-aluminum-garnet) was developed to determine concentration profiles of the fission product cesium in multilayered spherical coated-particle fuel. in addition, the system can be used for the simulation of cracked coatings by radical borings. The laser system with a Fabry-Perot-type resonator satisfies the requirements of small pulse width, absence of higher modes, and consistency of pulse energy. The formation of ''deep'' holes is explained theoretically by a self-channeling mechanism and briefly discussed. Techniques used for radial-distribution measurements for the fission product /sup 137/Cs in different irradiated coated particles are considered. Radially bored particles simulating cracked coatings are heat treated and fractional releases are measured. 7 refs