Cost of irradiation

It is clear from this discussion that the dose requirement and unit cost will be lower if the material has a higher molar mass M and the reaction has a high G value. Thus, the best candidates will be a polymeric material and a chain reaction. Quite often, a free-radical irradiation is used. The radiation source of choice is usually a 60Co - y facility, although electron beam irradiation is also used. Since most radiation-chemical reactions used in industry can also be brought about by other conventional means such as thermal, or photochemical processes, the processing cost must be below 10[Pg.366]

For polymerizing monomers into commodity resins, cost of irradiation would have to be reduced to the cost of catalyst in order to compete economically with the present commercial polymerization processes. For engrafting monomers to finished articles, the cost can be higher, especially when solvents are eliminated. 

The cost of irradiation—i.e., the cost of the curies—depends greatly on which reactor the cobalt is irradiated in. If irradiated in a reactor at high flux, the high specific activity material would be irradiated in 10 cans for... 

Radiation-induced changes in plastics can be reduced or increased by certain measures. Stabilization is desired for plastics used, e.g., in nuclear reactor construction, or intended to be sterilized by radiation. Here, irradiation doses can reach levels of several kGy at which plastic properties would already begin to change. Sensibilization, on the other hand, is desired for radiation-chemical processes to reduce the doses required for crosslinking or for other reactions, i.e., to lower the cost of irradiation. Stabilization and sensibilization thus can affect various parallel reactions either uniformly or selectively [710]. 

The throwaway fuel cycle does not recover the energy values present ia the irradiated fuel. Instead, all of the long-Hved actinides are routed to the final waste repository along with the fission products. Whether or not this is a desirable alternative is determined largely by the scope of the evaluation study. For instance, when only the value of the recovered yellow cake and SWU equivalents are considered, the world market values for these commodities do not fully cover the cost of reprocessing (2). However, when costs attributable to the disposal of large quantities of actinides are considered, the classical fuel cycle has been the choice of virtually all countries except the United States. 

The chief disadvantages of using radiation for industrial processing seem to be cost (in some cases), safety, and public and governmental concern over the long-term effects of irradiation. 

As for the relative suitability of an electron beam (EB) facility vis-a-vis a cobalt-60 gamma facility, a key point is that although the ultimate chemistry is nearly identical in both cases, there is a notable difference in the penetration of the radiations. Another point is that the large capacity and consequent cost of EB machines require a relatively large production rate to justify their use. On the other hand, the EB machine, not being a radioactive source, is completely safe when switched off. Overall, since the sixties, sterilization by irradiation has steadily increased. However, most of this is by cobalt-60 gamma irradiation, the EB machines accounting for about a fifth or sixth of the total number of facilities. 

Simultaneous UV and MW irradiation of the sample Possibility of performing photochemistry at high temperature Good photochemical efficiency — the EDL is inside the sample Simplicity of the experiment and the low cost of the EDL Use of a commercially available microwave oven Wireless EDL operation... 

In order to lower the cost of the nuclear reaction, enriched water is recovered after trapping the F-fluoride ions on an ion exchange resin [54,55]. For this reason and also because of scarcity of enriched water, the exploration of different target strategies is still searched. In examples, a frozen [ 0]carbon dioxide gas target [56] and irradiation of 2-fluoroaniline by 30-40 MeV photons [ F(y,n) F] [57] was shown to be efficient. However, the specific radioactivity still remains very low. 

A tenfold increase of the intensity may be obtained at the cost of a somewhat reduced thermal stability by omitting the draft shield and mounting the shutter and lamp assembly directly on top of the sample holder enclosure block. Since the heat production of the fluorescent lamp is very small the whole irradiation equipment could be mounted within the standard glove-box. 

Electrophilic trifluoromethylation is still of minor importance in synthetic applications. The limited efficiency and the cost of the reagents able to transfer a CF3 cation are important obstacles for the development of this approach. However, CF3-S" -type reagents can react with activated enolates under Lewis acid catalysis. A recent and promising result shows that, when the reaction is performed under UV irradiation, yields significantly increase. This can lead to synthetic applications, as exemplified by the recent preparation of 7-CF3 steroids (Figure 2.37). ... 

The cost of polymer irradiation depends on the type of polymer, formulation, and shape of the fabricated polymer. Upgrading polymers by electron beam radiation costs about 1 to 4 cents per pound. Some of this cost can be equalized through material saving in view of property improvement. Surface treatment might be as low as 0.1 to 0.2 cents per pound. 

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