Test Production of ⁶⁰Co Sealed Sources of High Specific Activity

Abstract

To establish the production technique of ⁶⁰Co sources with high specific activity, test production was started in 1967 by using JRR-3 and JMTR reactors. Two kinds of cobalt targets, a wafer type (diameter 8.0 mm × thickness 2.3 mm, 1.1 g) and a pellet type (diameter 1.0 mm × length 1.0 mm, 6.9 mg) were used. The former was irradiated at a maximum nvt of 4.4×10²⁰ neutrons per cm², yielding a maximum specific activity of 8.5 Ci per gram, and the latter at 2.2×10²¹ neutrons per cm², yielding a maximum specific activity of 68.1 Ci per gram, and the total activity of ⁶⁰Co sources amounted to 4.1 kCi. After the ⁶⁰Co sources were enclosed in stainless steel capsules, these sealed sources were submitted to wipe and immersion tests to examine surface contamination and leakage. Through the test production, could be obtained much important knowledge such as irradiation method, handling of highly active materials, sources assemblage and remote welding.