Future reactor developments

The most important development in the near future is the introduction of cluster tools (see figure 7.13) or integrated processing . At this moment about 20 cluster tools are available for various types of 

Blanket and selective tungsten plug processes are two of the first candidates for cluster tool integration. In the case of blanket tungsten the necessary process steps are  

1) Clean (sputter etch) of contacts/vias followed by adhesion layer sputter deposition. Instead of a sputtered adhesion layer a CVD adhesion layer like TiN can be applied. 

In the case of selective tungsten the process chambers could be  

1) Pre-deposition pretreatment chamber. This chamber can be either a plasma pretreatment chamber [Nowicki et al.250], a wet gaseous HF clean [van der Heide et al.250, Deal et al.250] or a methanol vapor exposure [Izumi et al.250]. 

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A similar set of processes has been partially developed for the thorium-uranium system but is not discussed here because it is not expected to be employed in the next several decades. The important feature of the thorium cycle is that it could be used to achieve breeding (to produce more fissionable material than is consumed) in thermal reactors, but nuclear as well as chemical factors have frustrated this development (for more information, see Reference 22). The increasing cost of the natural uranium supply for the ura-nium/plutonium cycle may, several decades in the future, justify development of the thorium cycle. 

The second year costs will be 3 billion to 6 billion. This will include site acquisition, evaluation of proposals, granting contracts, and construction of research and construction facilities. The research and construction facilities will serve as the foundation for the future production capacity for fusion reactors and floating platforms. We must maximize concurrent development, design and construction. The initial development of the Fusion-Hydrogen production equipment and production plants will require 5 to 10 years and cost about 200 billion. The construction sites and equipment will be designed for many years use in construetion of future reactors. The cost for the research and development of the Fusion-Hydrogen equipment and the investment in the reactor construction sites will be spread over all future reactors and ultimately reeovered. 

Most of the present nuclear reactors have been burning solid fuel elements of either normal or enriched uranium. Thus far, it has been necessary to reprocess fuel in order to recover valuable fissionable or fissile material. It is possible that fuel elements will be developed for future reactors which can be burned to the point where it is not economically justifiable to recover fissionable materials. Obviously, this depends upon the value of these materials. Such a procedure would provide an optimum solution to the major part of the waste disposal problem. The fission products would still be locked in the fuel element, simple disposal techniques could be employed, and in fact, spent fuel elements would probably have secondary uses as radiation sources. 

Future problems associated with separations and waste treatment processes, will be the result of two major changes in reactor development. These are the use of new materials of construction for fuel cladding or fuels themselves, and the increase in specific activity of processed fuels. 

There would be mutual benefits for both JNC and its partners in constructing the extranet and ISAN system. Obviously JNC would benefit from the vast experience of fast reactor operation amassed by our partners. But the success of Monju is also important for the future of fast reactor development outside Japan, and the communication would give our partners access to and operational reactor and new experience. 

This study aims at a comparison of future reactor concepts, paying particular attention to aspects of safety, of the fuel cycle, the economics, the experience-base and the state of development. Representative examples of typical development lines, that could possibly be of interesf within a time horizon of 50 years were selected for comparison. This can be divided into three phases ... 

Davis BH. (2003) Fischer-Tropsch synthesis overview of reactor development and future potentialities. Prep. Pap. Am. Chem. Soc., Div. Fuel Chem, 48(2) 787-790. 

In the subsequent sections, more attention will be given to the considerations affecting the choice of the coolant, moderator, and fuel element design for gas-cooled reactors. Developments in plant equipment will be discussed in greater detail. The choice of the fuel cycle and its effect on economics and the utilization of nuclear resources will be discussed. Finally, future trends in gas-cooled reactor designs will be indicated. 

The closure of the reactor and its subsequent decommissioning provided the opportunity, which may not recur, to conduct various tests and to obtain information of potentially inestimable value. AEA Technology, with the support of its industry partners in UK and EFR partners in Europe, drew up a number of proposals for work to be undertaken around the time of reactor closure. The aim of these was to be of value to future fast reactor development and, in particular, to the future plans of our European partners and for the support of the continued operation of the French fast reactors, particularly Superphenix. The programme also had the support in principle of the then Department of... 

Since the compositions in different droplets differ substantially, those of the alkylates produced in each obviously differ as well. Droplets 1 have high isobu-tane/olefin ratios, so the quality of alkylates produced in them tends to be high. Some alkylates are, however, produced in droplets 2, 3, and 4 since isobutane in these droplets can react with isoalkyl acid sulfates dissolved in the sulfiiric acid phase. Alkylates produced in droplets 3 have of course lower quality than those produced in droplets 2, since droplets 3 have lower concentrations of isobutane. A desired objective is to develop future reactors in which coalescence of droplets 1 and droplets 2 (or 3) is minimized. Relatively pure olefins are injected into the dispersions in some alkylation reactors with HF as the catalyst and hence produce droplets of relatively pure olefins. Such a technique would presumable promote undesired side reactions. 

Current Status and Future Technical and Economic Potential of Light Water Reactors, Prepared for Division of Reactor Development and Technology, USAEC,V WASH-1082 (March 1968). 

The conceptual design of the advanced reactor plant BN-1600 was completed in 1992, in full compliance with the up-to-date requirements for safety and economic efficiency of the new generation NPPs. It is expected that this design can be realized in Russian Federation not earlier than 2020, taking into account the fact that in the near future the fast reactor development programme in this country will be primarily focused on construction of the pilot BN-800 reactors, and creation of the closed nuclear fuel cycle production plants. This phase is of exceptional importance for the subsequent development of fast reactors and should precede their wide incorporation into the nuclear power park. 

In view of more than 40 years of worldwide fast reactor development experience, from experimental and prototype reactors up to economic demonstration, with very comprehensive international cooperation, it is not obvious that every country developing the technology in the future should without exception start by building an experimental fast reactor. On the other hand the development, design, construction and operation of an experimental fast reactor of a suitable power is necessary to decrease the economic risk of development. 

The 1985 Report devotes only 3 pages to Indian fast reactors and 10 to those of Japan. The contrast with the present report illustrates another change of major importance in the decade the increasing role of Asian countries in fast reactor development. In 1985 there was no mention of China or the Republic of Korea. By now it has become clear that these and other Asian countries where rapid economic growth is planned for will play a very large role in the future. 

The models for catalyst effectiveness in trickle bed reactors developed in this paper require explicit measurements or predictions of external contacting, ncE pore fill-up, rii In laboratory conditions this can be accomplished by tracer techniques (22, ). Fractional pore fill up may be determined by the difference in first moments of the impulse response tracer tests performed on two beds of same particle size and shape when one bed consists of porous the other of nonporous particles. Fractional pore fill-up can also be assessed from the measured volumetrically static holdup. External contacting is measured by adsorbable tracer tests on beds of nonporous particles ( ). In industrial conditions ncE hj would have to be evaluated from correlations. Unfortunately at present the existing correlations for ncE unsatisfactory since they were developed for fixed bed adsorbers with larger packing and correlations for m ate nonexistent but may be developed in the future. 

SYNOPSIS The choice of materials from which to construct a direct cycle nuclear reactor is limited by nuclear and engineering requirements and by the environment in which they are required to operate. Development of materials themselves are discussed in other papers presented at this symposium, whilst engineering requirements have been indicated elsewhere (ref. 1). This paper Is concerned solely with the chemical control of reactor circuits. Although a number of fluid circuits which require such control exist in the Wlnfrlth SGHWR, only two of the water circuits have been selected for discussion to Illustrate how the present systems came to be adopted and how subsequent development work has led to substantial Improvements which can now be incorporated with confidence in future reactors. 

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