Plutonium processing explosions

When the Plutonium Project was established early in 1942, for the purpose of producing plutonium via the nuclear chain reaction in uranium in sufficient quantities for its use as a nuclear explosive, we were given the challenge of developing a chemical method for separating and isolating it from the uranium and fission products. We had already conceived the principle of the oxidation-reduction cycle, which became the basis for such a separations process. This principle applied to any process involving the use of a substance which carried plutonium in one of its oxidation states but not in another. By use of this... 

In 1942, the Mallinckrodt Chemical Company adapted a diethylether extraction process to purify tons of uranium for the U.S. Manhattan Project [2] later, after an explosion, the process was switched to less volatile extractants. For simultaneous large-scale recovery of the plutonium in the spent fuel elements from the production reactors at Hanford, United States, methyl isobutyl ketone (MIBK) was originally chosen as extractant/solvent in the so-called Redox solvent extraction process. In the British Windscale plant, now Sellafield, another extractant/solvent, dibutylcarbitol (DBC or Butex), was preferred for reprocessing spent nuclear reactor fuels. These early extractants have now been replaced by tributylphosphate [TBP], diluted in an aliphatic hydrocarbon or mixture of such hydrocarbons, following the discovery of Warf [9] in 1945 that TBP separates tetravalent cerium from... 

Einsteinium does not exist in nature and is not found in the Earth s crust. It is produced in small amounts by artificial nuclear transmutations of other radioactive elements rather than by additional explosions of thermonuclear weapons. The formation of einsteinium from decay processes of other radioactive elements starts with plutonium and proceeds in five steps as follows ... 

Plutonium-239 and tritium for use as military explosives are the two major transmutation products. The nuclear process for Pu-239 production is the same as for energy generation, but there are some differences (a) metallic natural uranium clad with aluminum facilitates later dissolution for plutonium recovery, and the reactor operates at a relatively low temperature because of the aluminum clad and better heat transfer (due to the metallic natural uranium) (b) the irradiation cycle is limited to a few months to minimize the Pu-239 conversion to Pu-240 and Pu-241 and (c) a carbon or a heavy water moderator is used to increase the neutron efficiency. 

Following successful pilot-plant tests at Chalk River [N4], the Butex process was adopted for large-scale separation of plutonium, uranium, and fission products from natural uranium irradiated to low bumup at the Windscale plant of the U.K. Atomic Energy Authority [H8]. Even after its use in this application was replaced by the Purex process, the Butex process remained in use at Windscale for primary decontamination of high-bumup fuel until the 1970s. Then an explosion, probably due to reaction of nitric acid vnth solvent, terminated its use. 

In the PUREX process, the oxidizing property of nitric acid and the formation of nitrous acid are not favorable to maintain plutonium as a trivalent species. The sufficient amount of hydrazine is added to the system to ensure the stability of Pu(III) with the destruction of nitrous acid according to Equation 14.7. Despite the fact that hydrazine is particularly advantageous because the reaction products, N2/ N2O, and H2O, do not contribute to the volume of stored wastes (Schlea et al., 1963), the interaction of hydrazine and nitrous acid can initiate, in a TBP-nitric acid system, and under specific operating conditions, the formation of hydrazoic acid (HN3) which is a hazardous and potentially explosive compoimd (Equation 14.7) (Dukes and Wallace, 1962). Further oxidation leads to the formation of nitrous oxide and nitrogen gases as depicted in Equation 14.8... 

---