Bomb fusion methods

The demand for the determination proved so great that the method has been placed on a routine basis. One man can make 40 to 50 chlorine determinations on dry resins in an 8-hour day with a precision approaching that of the almost prohibitively time-consuming potassium fusion method. The Parr-bomb method permits about 40 analyses by two men in an 8-hour day, but precision suffers considerably when the work is done at this speed. 

A rapid procedure has been described10 based on sodium peroxide bomb fusion, for the determination of silicon and halogen in fluorine-containing organosilicon compounds and resins. The silicon is separated from the decomposition product as zinc silicate and estimated gravimetrically as silica. The filtrate is concentrated, acidified and, when necessary, reduced with sulphur dioxide. Chloride, bromide or iodide is then determined by the usual methods. Fluoride can be determined in neutral solution either gravimetrically as calcium fluoride, or volumetrically with zirconium tetrachloride or thorium nitrate, or directly in the decomposition solution by titration with zirconium tetrachloride. 

In the 1950s the necessary energy could also be reached by exploding a fission bomb, and methods were devised for using a fission bomb to spark off a still greater and more destructive variety of nuclear bomb. The result was what is variously called a hydrogen bomb, an H-bomb, a thermonuclear device but, most properly, a fusion bomb. 

In the fusion methods, cesium iodide is often added to the fusion mixture as a nonwetting agent to prevent the molten flux from adhering to the walls of the vessel, as well as to prevent incomplete transfer of the bead to the acid solution. In wet digestion of coal and fly ash using the Parr bomb, boric acid is added after digestion and the sample is heated for a further time on a water bath allowing the removal of unburned carbon. 

The use of larger particles in the cyclotron, for example carbon, nitrogen or oxygen ions, enabled elements of several units of atomic number beyond uranium to be synthesised. Einsteinium and fermium were obtained by this method and separated by ion-exchange. and indeed first identified by the appearance of their concentration peaks on the elution graph at the places expected for atomic numbers 99 and 100. The concentrations available when this was done were measured not in gcm but in atoms cm. The same elements became available in greater quantity when the first hydrogen bomb was exploded, when they were found in the fission products. Element 101, mendelevium, was made by a-particle bombardment of einsteinium, and nobelium (102) by fusion of curium and the carbon-13 isotope. 

Thallous Azidodithiocarbonate A637-L Thallous-Thallic Azide A623-R Thermonuclear or Fusion Bomb. See under Atomic Bomb A499-L Thorium Dicarbide A82-R Tin Azide A624-L Titanium Carbide A82-R Titanous Chloride Method for Determination of Nitrobenzene in Aniline A415-R TNT Recovery from Scrap Amatol A161-L Toluidine. See under Aminotoluenes A265-R... 

Typically, these will be alloys, rocks, fertilisers, ceramics, etc. These materials are taken into solution using suitable aqueous/acid media, according to solubility hot water, dilute acid, acid mixtures, concentrated acids, prolonged acid digestion using hydrofluoric acid if necessary, alkali fusion (e.g. using lithium metaborate), Teflon bomb dissolution. Fusion and bomb methods are usually reserved for complex siliceous materials, traditionally reluctant to yield to solubilisation. 

A complete and reliable analysis has shown our earlier conclusion concerning the oxyfluoride to be incorrect and has proved the empirical formula to be F,0,Pt (Found F, 32-4 O, iO-4 Pt, 57-5. F,0,Pt requires F, 33-4 O, 9-4 Pt, 57-2%). Fluorine was determined by a modified pyrohydrolytic method, and platinum by ignition in hydrogen of the hydroxide produced in the hydrolysis. Independent analysis was made for platinum by ignition of the solid in hydrogen (Found Pt, 57-4 %) and for fluorine by fusion of a sample with sodium in a Parr bomb (Found F, 327%). Oxygen was determined by displacement of the gas with bromine trifluoride. 

Two additional hydrofluoric acid methods have been reported (1,2), and are similar to that described above. The method of Hughes et al. has also been the subject of two comparative studies relevant to the analysis of ceramics (2,31). Techniques that retain silicon have been discussed (1,2) and involve either fusion with lithium metaborate [or sodium carbonate (2)] or high pressure dissolution in a PTFE bomb. An alternative high pressure method, developed by Price and Whiteside (32), was evaluated in the course of this investigation but was found to be unreliable for stained glass of medieval composition in many experiments dissolution was incomplete. Attempts to modify the procedure by varying the prescribed dissolution parameters produced insufficiently consistent results although superior conditions were established (Table I). 

Defoamers are used in fibre finishes in order to inhibit the formation of foam during the manufacturing and application of the finishes. Silicones and fluorochemicals are outstanding defoamers. They have very low surface tension and limited solubility in many organic compounds. They can quickly reduce the local surface tension of bubbles to create an imbalance of surface tension which leads to the easy rupture of bubbles. Silicones can be analysed using FUR. The analysis of fluorochemicals is difficult because fluorochemicals, especially perfluoro compounds, are resistant to many reagents. One microdetermination of fluorine by alkali fusion in a metal bomb was reported. Since it is too complicated and specialised apparatuses are used, this method is not introduced here. 

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. 

In the case of fluorine, doubts were thrown on the reliability of the oxygen bomb combustion. This method might give correct results for the analysis of some coal matrices but fusion should be systematically used in the case of fly ash consequently. 

A method has been described65 for the estimation of fluorine, chlorine and silicon, based on fusion with potassium metal in a bomb. The organosilicon sample is weighed in a gelatin capsule or polyethylene ampoule. Ignition and analysis of the melt are carried out as described above. 

D 2766 (1995) Test method for specific heats of liquids and solids D 3286 (1991) Test method for gross calorific value of coal and coke by the isoperibol bomb calorimeter D 3350 (1999) Polyethylene Pipes and Fitting Materials D 3386 (1994) Test method for coefficient of linear thermal expansion of electrical insulating materials D 3417 (1999) Test method for heats of fusion and crystallization of polymers by thermal analysis D 3418 (1999) Test method for transition temperatures of polymers by thermal analysis... 

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