Fusion lithium used

C22-0020. One proposal for controlled fusion involves using an accelerator to propel deuterons into a lithium target, inducing the following reactions ... 

Fusion power would not have the drawbacks associated with fission power, but no commercial fusion reactor is expected before 2050. In 2005, an international consortium consisting of the European Union, Japan, USA, Russia, South Korea, India, and China announced the 10 billion ITER (International Thermonuclear Experimental Reactor) project, which will be built in France to show within 30 years the technical feasibility of fusion power. Proposed fusion reactors use deuterium as fuel and in current designs also lithium. Assuming a fusion energy output equal to today s global need, the lithium reserves would last 3000 years. 

Tritium is produced in heavy-water-moderated reactors and sometimes must be separated isotopicaHy from hydrogen and deuterium for disposal. Ultimately, the tritium could be used as fuel in thermonuclear reactors (see Fusionenergy). Nuclear fusion reactions that involve tritium occur at the lowest known temperatures for such reactions. One possible reaction using deuterium produces neutrons that can be used to react with a lithium blanket to breed more tritium. 

The commercial ores, beryl and bertrandite, are usually decomposed by fusion using sodium carbonate. The melt is dissolved in a mixture of sulfuric and hydrofluoric acids and the solution is evaporated to strong fumes to drive off siUcon tetrafluoride, diluted, then analy2ed by atomic absorption or plasma emission spectrometry. If sodium or siUcon are also to be determined, the ore may be fused with a mixture of lithium metaborate and lithium tetraborate, and the melt dissolved in nitric and hydrofluoric acids (17). 

In recent years there has been a continued interest in the use of alkali metals, notably sodium and lithium, as heat exchange media in nuclear reactors and fusion systems respectively and as chemical reactants in fuel cells. This interest is reflected in the proceedings of several major conferences which are referenced in the bibliography (see p. 2.109). 

Substances which are insoluble or only partially soluble in acids are brought into solution by fusion with the appropriate reagent. The most commonly used fusion reagents, or fluxes as they are called, are anhydrous sodium carbonate, either alone or, less frequently, mixed with potassium nitrate or sodium peroxide potassium pyrosulphate, or sodium pyrosulphate sodium peroxide sodium hydroxide or potassium hydroxide. Anhydrous lithium metaborate has found favour as a flux, especially for materials containing silica 12 when the resulting fused mass is dissolved in dilute acids, no separation of silica takes place as it does when a sodium carbonate melt is similarly treated. Other advantages claimed for lithium metaborate are the following. 

For the preparation of samples for X-ray fluorescence spectroscopy, lithium metaborate is the preferred flux because lithium does not give rise to interfering X-ray emissions. The fusion may be carried out in platinum crucibles or in crucibles made from specially prepared graphite these graphite crucibles can also be used for the vacuum fusion of metal samples for the analysis of occluded gases. 

Are there any alternative chemicals which can be used to eliminate hazards (e.g., the use of lithium metaborate fusion rather than hydrofluoric acid as a dissolution procedure) The protocol should include details of any required checks on the control measures to be adopted, and their frequency (e.g., cleaning of protective clothing, washing down of fume cupboards). 

Most fusions use lithium tetraborate (Li2B407, m.p. 930°C), lithium metaborate (LiB02, m.p. 845°C), or a mixture of the two. A nonwetting agent such as KT can be added to prevent the flux from sticking to the crucible. For example, 0.2 g of cement might be fused with 2 g of Li2B407 and 30 mg of KI. 

Although detectable concentrations for several elements could be found after fusion, it is felt that the volatility of mercury and possibly lead and tin would make their determination by lithium tetraborate fusion questionable. Table I shows the elements selected for analysis and the accuracy and precision data for the standards used to check the fusion method. Each standard in Table I was of known composition and siliceous in nature. The standards were separately prepared 10 times so that a statistical evaluation of the results could be made. The standards used were USGS Standards G-2, W-l, BCR-1, commercially prepared silica-alumina based standards, and unfused synthetic standards prepared by the Coal Research Bureau (9, 10, 11, 12). The synthetic standards were used because no commercially prepared standard having... 

Lithium tetraborate has been found to be an excellent fusion agent enabling complete dissolution of silicate materials in acid for the analysis of major and minor constituents in coal. Carefully prepared standards matching the approximate concentrations of both the silica and alumina present in unknown samples permit determinations to be made with precision and accuracy. This method is currently being used to analyze coal ash and related materials. 

The D-T reactor is technologically more complex than the D-D reactor because of the need to facilitate the second reaction (which takes place outside the plasma) and because very energetic neutrons must be slowed down to allow the reaction with lithium to lake place. However, the conditions needed to achieve net power output are less demanding than for the D-D fuel reactor. The D-T reaction will probably be exploited first, but its ultimate, very long term use may be limited by the availability of lithium. See also Lithium (For Thermonuclear Fusion Reactors). 

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