[Test production of 60Co sealed sources of high specific activity (author's transl)]

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 mmxthickness 2.3 mm, 1.1g) and a pellet type (diameter 1.0 mmxlength 1.0mm, 6.9 mg) were used. The former was irradiated at a maximum nvt of 4.4x10(20) neutrons per cm2, yielding a maximum specific activity of 8.5 Ci per gram, and the latter at 2.2x10(21) 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.