Isotopes from irradiated molybdenum

Among the long-lived isotopes of technetium, only Tc can be obtained in weigh-able amounts. It may be produced by either neutron irradiation of highly purified molybdenum or neutron-induced fission of uraniimi-235. The nuclides Tc and Tc are exclusively produced in traces by nuclear reations. Because of the high fission yield of more than 6%, appreciable quantities of technetimn-99 are isolated from uranium fission product mixtures. Nuclear reactors with a power of 100 MW produce about 2.5 g of Tc per day . 

Although the fission products could be recovered as byproducts from the waste from spent nuclear reactor fuel, special-purpose neutron irradiation of highly enriched uranium (isotopically separated uranium-235) followed by chemical separation is the normal production method. The major products, molybdenum-99 and iodine-131 with fission yields of 6.1 and 6.7 percent, respectively, have important medical applications. Mo-99,... 

Technetium does not occur terrestrially, but has been observed in the spectra of the sun and certain stars. Perrier and Segre (1937) made the 90-day JTc by bombarding molybdenum with high-energy deuterons from a cyclotron. The isotope more useful as a tracer is the 60-day 43TC. The long-lived J Tc is obtained (Motta, Boyd and Larsen, 1947) by long irradiation of molybdenum in an atomic pile ... 

Among the long-lived technetium isotopes only the p -emitter Tc with a half-life of 2.13-10 a is obtained in vveighablc amounts, either by neutron irradiation of highly purified natural molybdenum or by induced fission of with thermal neutrons. Because of the high fission yield of 6.13 atom%, appreciable quantities of Te ean be isolated from uranium fission product mixtures. Nuelear reactors with a power of 3500 MWth produce about 100 g of Tc per day or 6 TBq ( 10 kg) c/GWn, per year. 

They had had to work for nearly half a year before they could present their tentative conclusions in a short letter to the London journal Nature. Briefly, the letter reported the first in history artificial synthesis of a new chemical element. This was element 43 the futile search for which on Earth wasted so much efforts of scientists from many coimtries. Professor E. Lawrence from the University of California at Berkley gave the authors a molybdenum plate irradiated with deutrons in the Berkley cyclotron. The plate exhibited a high radioactivity level which could hardly be due to any single substance. The half-life was such that the substances could not be radioactive isotopes of zirconium, niobium, molybdenum, and ruthenium. Most probably they were isotopes of element 43. 

Competition in the teletherapy market from linear accelerators cuts into CPO s sales and prompts it to launch an accelerator program of its own in the 1970s. Sales of industrial irradiators build steadily, while the isotope business surges on the strength of a new product, molybdenum-99,... 

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