Donald Cohen

The absorption spectra of plutonium ions in perchloric acid solutions

Abstract The absorption spectra of the four ions of plutonium have been measured in the region between 2000 and 12,500 A in perchloric acid solutions.

Electrochemical studies of plutonium ions in perchloric acid solution

Abstract A potentiostat was used to obtain current-voltage curves for the oxidation-reduction reactions of plutonium ions and to prepare the four valence states of plutonium in perchloric acid solutions.

The preparation and spectrum of uranium(V) ions in aqueous solutions

Abstract Uranium(V) ions have been prepared in concentrated chloride solutions and in aqueous carbonate solutions. The absorption spectra of the uranium(V) ions in these solutions have been measured.

Some observations of Np(VI) in chloride solutions

Results are given which show that the reduction of Np(Vl) in chloride media is very slow at room temperature, not differing greatly from that expected from auto-reduction, and that a satisfactory absorption spectrum can be obtained. The accelerated reduction observed in the presence of platinum is shown not to be due to a catalytic effect but to reduction by the platinum itself. The reduction of Np(VI) was iound to be a iittle faster in both DClO/sub 4/ and DCi in HClO/sub 4/ but still very slow. A major peak occurs at a longer wavelength in 2 M DCl than in 2 M DClO4 and its molar extinction coefficient is increased from 46 to 2 M DClO/sub 4/ to 54in2 M DCl. (P.C.H.)

The photochemical reduction and the autoreduction of neptunium(VI)

Abstract It was found that exposure of Np(VI) perchlorate solutions at 25° to 2537 A light results in the formation of Np(V) with an apparent quantum yield of 0·032 ± 0·011. In addition the rate constant for the autoreduction of Np(VI) → Np(V), due to the radiolysis caused by the α-decay of 237 Np, was measured as k = 3·1 ± 0·2 × 10 −9 sec −1 . This result is discussed in comparison with the autoreduction rate constants of Pu(VI) and Am(VI).

Half-life of 239Np☆

The best value for the half life of neptanium-239 was determined to be 2.359 plus or minus 0.010 days. (C.J.G.)

The Radiolytic Oxidation and Reduction of Plutonium

It has been shown on several occasions that all other things being equal, the rate of migration of plutonium through an aquifer is greatly influenced by its oxidation state. It is a reasonable expectation that other actinides exhibiting multiple oxidation states will behave similarly. By and large the more highly charged ions in solution move through rock strata more slowly than those of lesser charge. Thus from comparative experiments on the relative migration rates of Pu(IV) and Pu(III) we would expect Pu(III) to move about 10 times faster than Pu(IV)* and it has been shown Pu02+ moves about 250 times more rapidly than Pu(IV) (1).

The Use Of 222 Rn as a Flow Path Monitor for Studies of Radionuclide Transport in Fissures

A technique has been developed using 222 Rn as a flow path monitor. Its principle advantage over other radiotracers or dyes is that while the Kd of Rn gas in water solution is zero and hence follows the water path, its 210 Pb daughter is retained strongly by rock. The immobilized 210 Pb is not subject to diffusion, an important consideration in the proposed Nevada Field Test. To evaluate the technique, a series of laboratory scale experiments have been performed. Artificial fissures consisting of glass plates and prepared flat surfaces were coupled to insure well characterized fissures. Water solutions of radiotracer were metered through these fissures and the discharge monitored to produce breakthrough curves as a function of flow rate. The rock surfaces were analysed for radionuclide concentration and the rock sectioned for diffusion profile into the rock.