Beryllium Pebbles Preparation and Modeling of Rotating Electrode Process

Abstract

High-purity beryllium in the form of spherical pebbles of size ranging from 0.2 to 2 mm are required for neutron multiplication in the test blanket module of the helium-cooled solid breeder in ITER. The pebbles should be dense and have stringent chemical composition to withstand a high-temperature and irradiation environment. Hence, the conventional method of preparing beryllium pebbles has to be modified to a novel technique such as the rotating electrode process (REP). In the present paper REP modeling, design, and selection of process parameters to control the particle size have been carried out. Based on the results on the preparation of surrogate stainless steel spherical pebbles, beryllium pebbles have been prepared by REP, and the results obtained are presented. The important parameters that affect the pebble size and production rate are found to be anode diameter, material constants, revolutions per minute, arc gap, and the cooling cover gas in the REP chamber. The pebbles once formed are kept in levitated condition in the chamber for achieving near-perfect spherical shape. This paper also focuses on beryllium pebble handling with respect to safety and industrial hygiene control as per the prescribed international standard.