Characterization of Solidified Products Yielded by Plasma Melting Treatment of Simulated Non-Metallic Radioactive Wastes

Abstract

As a part of an advanced volume reduction program for low level radioactive wastes in JAERI, melting tests of non-metallic solid wastes have been conducted with the aim of establishing the optimum melting condition for preparation of a stable solid that is suitable for disposal. Simulated non-metallic wastes containing ⁶⁰Co, ¹³⁷Cs and ¹⁵²Eu tracers were melted with a plasma torch of a non-transferred type, and the examination was carried out on chemical composition and physical properties of solidified products and the distribution of tracers in each product. The products were almost homogeneous and possessed satisfactory mechanical strength for disposal. The radioactive nuclides were almost uniformly distributed in the products. The amount of ¹³⁷Cs remaining in the products depended on the basicity of slag, while that of ⁶⁰Co was not. A small amount of fine metal particles containing ⁶⁰Co was observed in a slag. This was attributable to partial reduction of metal oxides under the relatively reductive atmosphere.

KEYWORDS:

• low level radioactive wastes
• non-metallic solid wastes
• plasma melting
• solidified products
• radioactive nuclide distribution
• slag basicity
• cesium 137
• cobalt 60