Reactor alternative options

Figure 3.18 Generic process reactor alternatively equipped with PAT sensors or probes, shown at typical deployment locations at different reactor heights. TOS analysis again results in rejection of all options presented. The critique leveled against incorrect PAT sensor deployment in ducted flow (Figure 3.16) applies in full force for reactor sampling as well.

To improve the intrinsic economics of nuclear electrolysis, in the long term, hydrogen production by high-temperature electrolysis coupled with high-temperature nuclear reactors is an attractive alternative option. Today, high-temperature electrolysis is at an early stage of development, see Figure 5. Size... 

Many alternative options can be considered for productive use of reject heat at any of the three temperatures. Moreover, the passive safety / passive load-follow design of the reactor facilitates siting it in industrial parks near urban areas and / or close to cities - facilitating cogeneration opportunities. 

Fuel cycle options, alternative - Option ofproduction in blankets (for future thermal reactors)... 

Armed with the PFS and the questions for the various process options the team can then discuss the most appropriate way forward. For example considering question 2, production staff may comment that this particular plant only runs on the day shift, so a 10-hour reaction is not viable the chemical engineer may conclude that the problem is likely to be one of mass transfer, and other reactor design options such as a spinning disc reactor should be considered. The SHE advisor may comment that not only is solvent 1 volatile but it is also moderately harmful and would require specialist handling equipment, hence it is very important to find an alternative. As waste minimization starts at the reaction stage it is critical to study this area in particular detail. Questions that can be asked include ... 

Two sample ALD reactor design options are presented schematically in Figure 12.19. Not shown is a conventional MBE environment such as in Figure 11.1. The CVD-type reactor designs may include a conventional CVD reactor tube (hot or cold wall) with pulsed gas sources sending bursts of one reactant and then the other down the tube. This relies on sufficient physical separation of the pulses in the gas phase as the reactant pulse travels down the tube. A second method is to expose a surface sequentially to reactants supplied at fixed locations by rotating the substrate alternately over each. 

Various ways of overcoming the PTA oxidation problem have been incorporated into commercial processes. The predominant solution is the use of high concentrations of manganese and cobalt ions (2,248—254), optionally with various cocatalysts (204,255,256), in the presence of an organic or inorganic bromide promoter in acetic acid solvent. Operational temperatures are rather high (ca 200°C). A lesser but significant alternative involves isolation of intermediate PTA, conversion to methyl/)-toluate, and recycle to the reactor. The ester is oxidized to monomethyl terephthalate, which is subsequentiy converted to DMT and purified by distillation (248,257—264). 

Spent Fuel Treatment. Spent fuel assembhes from nuclear power reactors are highly radioactive because they contain fission products. Relatively few options are available for the treatment of spent fuel. The tubes and the fuel matrix provide considerable containment against attack and release of nucHdes. To minimi2e the volume of spent fuel that must be shipped or disposed of, consoHdation of rods in assembhes into compact bundles of fuel rods has been successfully tested. Alternatively, intact assembhes can be encased in metal containers. 

On the other hand, RPBs suffer from poor heat transfer possibilities. Heat input could theoretically be achieved by use of eddy currents, microwaves, or sonic energy, and thus endothermic reactions are, in principle, possible. The heat removal is more problematic and exothermic reactions must be conducted adiabatically within the rotor. Alternating packing and heat transfer plates could perhaps be an option, although it would greatly increase the complexity and the price of the reactor. 

A permanent geologic repository is also important to our non-proliferation goals an alternative to reprocessing. . . storage for foreign research reactor fuel. . . and an option for the disposition of surplus plutonium from nuclear weapon stockpiles. 

Where the hazard is an exothermic runaway reaction, there are number, of alternative measures that may be used either to prevent or control runaway. Informatipn on the various options is in Annex 1. In the UK, one of the most commonly selected measures used to protect reactors from exothermic runaway is an emergency relief system. These have a number of advantages ... 

Kokossis and Floudas (1994) extended the MINLP approach so as to handle nonisothermal operation. The nonisothermal superstructure includes alternatives of temperature control for the reactors as well as options for directly or indirectly intercooled or interheated reactors. This approach can be applied to any homogeneous exothermic or endothermic reaction and the solution of the resulting MINLP model provides information about the optimal temperature profile, the type of temperature control, the feeding, recycling, and by-passing strategy, and the optimal type and size of the reactor units. 

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