Bromine radioactive, production

Some radioactive bromine (half-life 36 hours), in the form of ammonium bromide, was put into a brine stream as a radioactive tracer. At another plant 30 km away, the brine stream was electrolyzed to produce chlorine. Radioactive bromine entered the chlorine stream and subsequently concentrated in the base of a distillation column, which removed heavy ends. This column was fitted with a radioactive-level controller. The radioactive bromine affected the level controller, which registered a low level and closed the bottom valve on the column. The column became flooded. There was no injury, but production was interrupted. 

The irradiated sample, diluted with Alundum in a porcelain boat containing mercuric nitrate carrier, is combusted very slowly in a slow oxygen stream in a 96% silica combustion tube. The volatile products are collected in two consecutive traps, both containing a solution of acetic acid-sodium acetate buffer, bromine, and mercuric nitrate hold-back carrier. The collection solutions in 2N HC1 are loaded onto Dowex 2, and radioactive interferences are eluted with aliquots of water and 2N HC1. The resin, in a small vial, is counted for the 0.077 MeV photopeak from 197Hg. 

Radioactivation analysis has been used to measure bromine in polymers (37—39) and recently a novel technique for trace oxygen has been reported (40). Any polymer or other material (e.g. metal alkyl) which is miscible with butyl lithium solutions may be analysed since the procedure involves the intermediate production of triton particles by the nuclear reaction 6Li (n, a) t. The tritons then act as nuclear projectiles for the activation of oxygen 0 (t, n) 18F and the radioactivity due to fluorine-18 is measured. A sensitivity of 1 x 10 g in a 0.5 g sample is claimed. 

Suppose now that we introduce a small amount of a radioactive tracer into the system, for example, radioactive bromine, Br, in the form of Br2. By small we mean that the amount of added Br2 is negligible with respect to the equilibrium amount of Br2 already present in the system. Under these circumstances the addition of radioactive material will not disturb the equilibrium at the same time the radioactive bromine will begin to react and distribute itself between the Br2 and NOBr already present. If we assume that radioactive Br2 molecules react at the same rate as normal Br2, then we can say that the rate of production of radioactive NOBr, Rnobf, is given by... 

There is a limit to the negative period that can be developed in a reactor by negative reactivity additions. Soon after the insertion of a large amount of negative reactivity such as a scram, the prompt neutron population decreases to a low level. Neutron population is predominantly the result of delayed neutrons which are produced by fission product decay. Within a short time, 2-3 minutes, all of the short lived delayed neutron precursors have decayed away. At this point, and from this point on, the core neutron population is sustained by decay of the longest lived fission product precursor, bromine-87, with a half life of = 55.72 seconds. Since the rate at which core neutron population decreases is determined by radioactive decay of bromine-87, an effective reactor period can be calculated by setting equations (2,9) and (4.7) equal. Neutron population, N will be used to replace activity, A, and power, P, respectively in the two equations. 

Vicinardibromides may be debrominated by treating them with certain reducing agents, including iodide ion and zinc. The stereochemical features of these reactions were examined using labeled 1,1,2-tribromocyclohexane prepared by anti addition of bromine-82 to bromocyclohexene. The radioactivity of Br permits determination of the stereochemical course of the reaction, since unlabeled bromocyclohexene would be the exclusive product of anti elimination, while Br-labeled bromocyclohexene would result from syn elimination. Debromination with sodium iodide was found to be cleanly an anti elimination, while debromination with zinc gives mainly, but not entirely, anti elimination. 

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