The Production of Plutonium

The production of plutonium metal by both fluoride and oxide reduction is well established at Los Alamos. The subsequent purification of this metal by electrorefining is now being performed in production on a 6-kg batch scale. The objective is the production of high-purity plutonium metal. 

Fuel reprocessing has three objectives (a) to recover U or Pu from the spent fuel for reuse as a nuclear reactor fuel or to render the waste less hazardous, (b) to remove fission products from the actinides to lessen short-term radioactivity problems and in the case of recycle of the actinides, to remove reactor poisons, and (c) to convert the radioactive waste into a safe form for storage. Fuel reprocessing was/is important in the production of plutonium for weapons use. 

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate. Nuclear reactors are used for many purposes, but the most significant current uses are for the generation of electrical power and for the production of plutonium for use in nuclear weapons. Currently, all commercial nuclear reactors are based on nuclear fission. The amount of energy released by one kg 235U is equal to the energy from the combustion of 3000 tons of coal or the energy from an explosion of 20,000 tons of TNT (Trinitrotoluene, called commonly dynamite). 

Previous experience in the production of plutonium 238 revealed the need for the double alpha containment of the cells where the alpha-emitter isotopes with high specific activity are handled. Thus all the hot cells are equipped with a double ventilation system which provides ventilation of alpha-cells and ventilation between alpha-cells and biological shields. Alpha detectors continuously monitor the exhaust circuits. 

Reactor fuel for the production of plutonium and target manufacture for the production of tritium involves the use of material and machinery common to other manufacturing industries with the exception of uranium and possibly enriched lithium. Aqueous waste from such operations may find its way to surface water systems and is the primary source for short- and long-range detection. 

The production of plutonium fuel (plutonium-239) is a fascinating story. When nuclear reactors were first built, they all used uranium-235 as a fuel. Of the three naturally occurring isotopes of uranium, only uranium-235 will undergo fission. 

The first transuranic element was produced in 1940. Neptunium (Z = 93) results from the capture of a neutron by U, followed by beta decay. Subsequent work by the American chemist Glenn Seaborg and others led to the production of plutonium (Z = 94) and heavier elements. In recent years, nuclides with Z as high as 116 have been made, but in tiny quantities. These nuclides have very short half-lives. 

A scheme has been proposed for using the neutrons from the fusion reaction to convert uranium 238 to plutonium 239 or thorium 232 to uranium 233 for the manufacture of bombs. While in theory this may be possible, it does not appear to offer an easier route to the produetion of bombs than the current methods of separation of uranium 235, or the production of plutonium in a conventional reactor. As a result of these factors, use of a fusion energy system will in no way add to the potential for further nuclear weapons or provide a source for the unauthorized procurement of materials that might be used to produce weapons. 

Describe the problems associated with the production of plutonium-239 in nuclear reactors. 

PuFs and Pup4 are important intermediates in the production of plutonium metal. The trifluoride is made by reacting PuOi with a mixture of HF and Hj at 600° C ... 

Plutonium exists in trace quantities in naturally occurring uranium ores (Weast 1980). Plutonium is produced by the bombardment of uranium with neutrons. The most important isotope, plutonium-239, is produced in large quantities from natural uranium in nuclear reactors (Weast 1980). Plutonium- 240, -241, and -242 are produced from successive absorption of neutrons by the plutonium-239 atoms. The successive absorption of two neutrons rather than one by uranium leads to the production of plutonium-238. Plutonium-237 is usually produced by the helium ion bombardment of uranium-235. 

The majority of plutonium was produced for nuclear weapons in several government reactors designed to maximize the production of plutonium. Betw een 1944 and 1988, the U.S. built and operated these production reactors at high-security government facilities. In all, the U.S. produced about 1(X) metric tons of plutonium. 

The MASWR is a light water reactor with a conversion ratio of less than unity. The modification of the facility to operate as a fast reactor for the production of plutonium is not probable because of the isotopic content, and the small core size with poor fast neutron economy. Also, the core unit is treated as a module, preventing the reactor from being used for irradiation of fertile material by placement of a dummy fuel assembly in the core unit. 

This enhances the production of plutonium in the reactor and also makes the lattice fall-safe (from a reactivity standpoint) upon loss of water. 

The production of plutonium was a prime justification for building NRU and took precedence over other uses. Some would be used for reactor experiments in Canada, but it was expected that most would be exported to the United States for atomic bombs. Isotope production came next on the list of priorities, so CPD would have fair access to the reactor. NRU started up on November 3, 1957. After a shakedown period, irradiations began. In May 1958, a fuel rod broke as it was being withdrawn from the reactor, causing a radioactive spill that delayed cobalt-60 production to late 1959. 

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