Manufacturing of an Iridium-192 Ionizing Radiation Source for Nondestructive Testing

The optimal regimes of irradiation of metal disks of natural iridium with thermal neutrons of the WWR-SM reactor were found and the radionuclide 192Ir with high specific activity (up to 250 Ci/g) was obtained. To determine the flux density of thermal neutrons and their distribution along the vertical channel, a TND-2.0 thermoneutron sensor and 59Co monitors in the form of a disk - foil (∅ = 3.0 mm, h = 0.2 mm, m = 3.0 mg) containing an alloy of aluminum and 59Co (0.01%) were used. The maximum values of the potential difference and thermal neutron flux densities are observed at a distance of 35-45 cm down from the top point of the vertical channel (or 35–45 cm down from the top point of the IRT-4M fuel assembly head). The observed high values of cadmium ratios show that neutron activation of natural iridium is mainly due to thermal neutrons. With increase in the thickness of the iridium disk, the yield of the induced activity of the 192Ir radionuclide decreases. Packages of natural iridium disks were irradiated with thermal neutrons in the vertical channel of the reactor, radiochemically processed and manufactured ionizing radiation sources of 192Ir with activity of 50–120 Ci, which were tested for tightness by the immersion method. A test of a sample of a metal pipe with a diameter of 219.0 mm, a wall thickness of 8.0 mm with a welded seam through two walls, carried out with an 192Ir source of non-destructive testing of welding quality, showed a good result and the obtained gamma-graphic images in terms of sensitivity and quality corresponded to the requirements of GOST-7512- 82 “Control non-destructive. Welded joints ”(Russia) and ASME (USA). The sources of 192Ir with gammaray flaw detectors Gammarid-192/120M were used for non-destructive testing of the quality of welded joints of pipelines at the construction objects of the Talimarjan TPP, Takhiyatash TPP and the Kandym gas processing plant of the Republic of Uzbekistan.

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