METHOD FOR PRODUCING FLAW-DETECTION GAMMA-RADIATION SOURCE Russian patent published in 1996 - IPC

FIELD: flaw inspection. SUBSTANCE: for producing selenium-75 base gamma radiation, source compound (natural metallic selenium) is treated upon analysis of chemical purity with gaseous fluorine at 100 C and atmospheric pressure according to reaction ⁷⁴Se+F₂__→ ⁷⁴SeF₆+1029 kL/mol while controlling mixture composition within 10-25 % for fluorine. Mixture is enriched by means of tandem gas centrifuges according to molecule ⁷⁴SeF₆ up to at least 96% content of selenium-74 isotope upon optimization of hydraulic and separating characteristics of centrifuges. Hexafluoride is converted in to metallic selenium-74 at 250-270 C according to reaction with gaseous ammonia 2NH₃+⁷⁴SeF₆__→ ⁷⁴Se+6HF+N₂, while feeding purified argon to prevent back reaction. Metallic argon-74 obtained is subjected to analysis for chemical purity and then repeatedly press-fitted into chemically resistant and nonactivating capsule, such as titanium one, up to density of at least 3 g/cu cm; capsule is than sealed by laser welding at the same time ensuring proper heat transfer and irradiated at continuous heat transfer in reactor thermal-neutron flux of density not lower than 10¹⁵ n/sq cm s. Then capsule is placed in other corrosion-resistant and mechanically strong capsule, such as made of stainless steel, and sealed by argon-arc welding. EFFECT: improved reliability of source, facilitated procedure.