Supercritical water reactor

Involved in extensive study of SCWO processes Investigated SCWO process for pulp mill sludges Explored kinetics of SCWO of phenol Explored supercritical water reactor Investigated the unique features of supercritical water in terms of density, dielectric constant, viscosity, diffusivity, electric conductance, and solvating ability Explored multistep kinetic model of phenol in SCWO Involved in extensive SCWO study of priority pollutants... 

Session 4 focused on recent advances in the thermochemical copper chloride and calcium bromide cycles. Much of the current research on thermochemical cycles for hydrogen production involves the sulphur cycles (sulphur-iodine, hybrid sulphur), however, these cycles require very high temperatures ( 800-900°C) to drive the acid decomposition step. The interest in the Cu-Cl and Ca-Br cycles is due to the lower peak temperature requirements of these cycles. The peak temperature requirement for the Cu-Cl cycle is about 550°C, which would allow this cycle to be used with lower temperature reactors, such as sodium- or lead-cooled reactors, or possibly supercritical water reactors. Ca-Br requires peak temperatures of about 760°C. Both of these cycles are projected to have good efficiencies, in the range of 40%. Work on Cu-Cl is ongoing in France, Canada and the United States. Work on Ca-Br has been done primarily in Japan and the US, with the more recent work being done in the US at ANL. The papers presented in this session summarised the recent advances in these cycles. 

The whole set of possible thermochemical cycles has been considered and ranked based on a list of predefined criteria such as levels of temperatures required, rarity or toxicity of the reactants, number of electrochemical steps,. This led to the selection of a few cycles of interest (Mg-I, Ce-Cl and Cu-Cl). After further evaluation, Cu-Cl (shown in Figure 8) was retained. This cycle presents the advantage of dealing with only moderate temperature reactions (< 530°C), which offers the possibility of coupling it with other Gen-IV systems such as the Sodium Fast Reactor and the Supercritical Water Reactor. 

The Cu-CI thermochemical cycle has been under development for several years. The goal is to achieve a commercially viable method for producing hydrogen at a moderate temperature ( 550°C). This chemical process, if successfully developed, could be coupled with several types of heat sources, e.g. the supercritical water reactor, the Na-cooled fast reactor or a solar heat source such as the solar power tower with molten salt heat storage. The use of lower temperature processes is expected to place less demand on materials of constmction compared to higher ( 850°C) temperature processes. 

The copper-chloride hybrid thermochemical cycle is one of the best potential low temperature thermochemical cycles for the massive production of hydrogen. It could be used with nuclear reactors such as the sodium fast reactor or the supercritical water reactor. Nevertheless, this thermochemical cycle is composed of an electrochemical reaction and two thermal reactions. Its efficiency has to be compared with other hydrogen production processes like alkaline electrolysis for example. 

Among the various low temperature thermochemical cycles described in the open literature, the copper-chloride hybrid thermochemical cycle is a very promising candidate. It has been studied extensively at Argonne National Laboratory, USA and in AECL, Canada where it is scheduled to be coupled with a supercritical water reactor. 

Supercritical water reactor (SCWR), with a direct power cycle ... 

Like supercritical carbon dioxide, supercritical water is a very interesting substance that has strikingly different properties from those of liquid water. For example, recent experiments have shown that supercritical (superfluid) water can behave simultaneously as both a polar and a nonpolar solvent. While the reasons for this unusual behavior remain unclear, the practical value of this behavior is very clear It makes superfluid water a very useful reaction medium for a wide variety of substances. One extremely important application of this idea involves the environmentally sound destruction of industrial wastes. Most hazardous organic (nonpolar) substances can be dissolved in supercritical water and oxidized by dissolved 02 in a matter of minutes. The products of these reactions are water, carbon dioxide, and possibly simple acids (which result when halogen-containing compounds are reacted). Therefore, the aqueous mixture that results from the reaction often can be disposed of with little further treatment. In contrast to the incinerators used to destroy organic waste products, a supercritical water reactor is a closed system (has no emissions). 

As for the nuclear-heated steam reforming of synthetic crude, the medium temperature recirculation-type membrane reforming process (Ref. 10) can be applied, where either SFR (sodium fast reactor) or SCWR (supercritical water reactor) could be adopted as medium-temperature heat source. 

Reactor type LWR (Light Water Reactor), VHTR (Very High Temperature Gas Reactor), SFR (Sodium Fast Reactor), SCWR (Supercritical Water Reactor). 

In future generations of nuclear reactors - especially supercritical water reactors (SCWR), 4th generation nuclear reactors and the ITER project (International Thermonuclear Experimental Reactor) - water should still be considered as a suitable coolant fluid, but it will be submitted to more extreme conditions of temperature and LET (high flux of neutrons). All contemporary studies show that it will be beyond reach to extrapolate the existing simulations to these new conditions without experimental determinations of essential parameters such as radiolytic yields and rate constants. 

Because oxygen, carbon dioxide, methane, and other alkanes are completely miscible with dense supercritical water, combustion can occur in this fluid phase. Both flameless oxidation and flaming combustion can take place. This leads to an important application in the treatment of organic hazardous wastes. Nonpolar organic wastes such as polychlorinated biphenyls (PCBs) are miscible in all proportions in supercritical water and, in the presence of an oxidizer, react to produce primarily carbon dioxide, water, chloride salts, and other small molecules. The products can be selectively removed from solution by dropping the pressure or by cooling. Oxidation in supercritical water can transform more than 99.9 percent of hazardous organic materials into environmentally acceptable forms in just a few minutes. A supercritical water reactor is a closed system that has no emissions into the atmosphere, which is different from an incinerator. 

Magill, M., Pencer, J., Pratt, R., Young, W., Edwards, G.W.R., Hyland, B., 2011. Thorium fuel cycles in the C ANDU supercritical water reactor. In Proc. 5th Int. Sym. SCWR (ISSCWR-5), Vancouver, British Columbia, Canada, Match 13—16, 2011. 

Ruzickova, M., Schulenberg, T., Visser, D.C., Novotny, R., Kiss, A., Maraczy, C., Toivonen, A., 2014. Overview and progress in the European project supercritical water reactor — fuel qualification test . Progress in Nuclear Energy 77, 381—389. 

Figure 10.1 2013 Generation-IV International Forum Roadmap—viability, performance, and demonstration phases. GFR, gas-cooled fast reactor LFR, lead-cooled fast reactor MSR, molten salt reactor SCWR, supercritical water reactor SFR, sodium-cooled fast reactor VHTR, very-high—temperature reactor.

Russian has signed the Generation IV International Forum Supercritical Water Reactor (SCWR) System Arrangements in 2011, and the work remains at a level of conceptual studies. Several SCWR concepts have been developed since the 1990 s and much stiU remains for future investigation. 

Yurmanov, V.A., Belous, V.N., Vasina, V.N., Yurmanov, E.V., 2009. Chemistry and corrosion issues in supercritical water reactors. In IAEA International Conference on Opportunities and Challenges for Water Cooled Reactors in the 21st Century. Vienna, Austria. 

SCWR (Supercritical Water Reactor Supersafe AECL) Hybrid Power Technologies advanced reactor PRISM (Power Reactor Innovative Small Module General Electric)... 

Dutta, G., Zhang, C., Jiang, J., 2015. Analysis of parallel channel instabilities in the CANDU supercritical water reactor. Annals of Nuclear Energy 83, 264—273. 

Rosen, M.A., Naterer, G.F., Chukwu, C.C., Sadhankar, R., Suppiah, S., 2012. Nuclear-based hydrogen production with a thermochemical copper—chlorine cycle and supercritical water reactor equipment scale-up and process simulation. International Journal of Energy Research 36 (4), 456—465. 

J.H. Wright, J.F. Paterson, Status and application of supercritical-water reactor coolant, in Ptoc. Am. Power Conf. 26—28 April 1966, Chicago vol. XXVm, 1%6, pp. 139—149. 

L. Qiu, D.A. Guzonas, Prediction of metal oxide stability in supercritical water reactors —Pourbaix versus Elhngham, in The 3rd Canada-China Joint Workshop on Supercritical Water-Cooled Reactors (CCSC-2012), Xian, China, April 25—28, 2012. 

R.P. Olive, Pourbaix Diagrams, Solubility Predictions and Corrosion-product Deposition Modelling for the Supercritical Water Reactor (Ph.D. thesis), University of New Brunswick, Department of Chemical Engineering, 2012. 

M.C. Udy, F.W. Boulger, Survey of Materials for Supercritical-water Reactor, Battelle Memorial Inst, Columbus, Ohio, November 27, 1953. OSTI ID 4230973, Report Number(s), BMI-890. 

S. Teysseyre, Corrosion issues in supercritical water reactor (SCWR) systems, in D. Feron (Ed.), Nuclear Corrosion Science and Engineering, Woodhead Publishing Ltd., 2012. 

Figure 2. Coolant circuit of a supercritical water nuclear reactor. Note that the entire coolant circuit operates at a temperature above the critical temperature of 374.15°C. Reprinted from http //en.Wikipedia, org/wiki/ Supercritical water reactor.

T. T. Yi, S. Koshizuka and Y. Oka, A Linear Stability Analysis of Supercritical Water Reactors, (I) Thermal-Hydraulic Stability, Journal of Nuclear Science and Technology, Vol. 41(12), 1166-1175 (2004)... 

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