Nuclear steam reheat

Key water chemistry issues have been identified by Guzonas et al. (2012) predicting and controlling water radiolysis and corrosion product transport (including fission products) remain the major R D areas. In this regard, the operating experience using nuclear steam reheat at the Beloyarsk nuclear power plant (NPP) in Russia is extremely valuable. 

Appendix A5 World experience in nuclear steam reheat ... 

To achieve higher thermal efficiency, nuclear steam reheat has to be introduced inside a reactor. Currently, aU supercritical turbines at thermal power plants have a steam reheat option. In the 1960s and 1970s, Russia, the US, and some other countries have developed and implemented nuclear steam reheat at subcritical pressures in experimental reactors. Therefore, it is important to summarize the worldwide expmence of implementing nuclear steam reheat at several experimental boiling water reactors (BWRs) and utilize it in the context of development of SCWRs concepts with a steam reheat option. 

An active program for the development and demonstration of BWRs with nuclear steam reheat was implemented and directed by the United States Atomic Energy Commission (USAEC). Two general types of the reactors were pursued ... 

This chapter is mainly based on Saltanov, Eu. and Pioro, I., 2011. World Experience in Nuclear Steam Reheat, Chapter in book Nuclear Power Operation, Safety and Environment , Editor P.V. Tsvetkov, INTECH, Rijeka, Croatia, pp. 3—28. Eree download ftom http //www.intechopen.com/books/nuclear-power-operation-safety-and-environment/world-experience-in-nuclear-steam-reheat. 

Based on the US experience with nuclear steam reheat, it may be concluded that the nuclear steam reheat is possible and higher thermal efficiencies can be achieved however, this implementation requires more complicated reactor core design and better materials. 

This section presents a unique compilation of materials that overviews aU major aspects of operating experience of the first in the world industrial NPP with implemented nuclear steam reheat. 

Reactors with nuclear steam reheat were also developed in the former Soviet Union. The Beloyarsk Nuclear Power Plant (BNPP) was the first NPP in the world where nuclear steam reheat was implemented on industrial level. Two reactors (100 MWei and 200 MWei) were installed with identical steam parameters at the turbine inlet (Pjj, = 8.8 MPa and T n = 500—510°C). The first reactor (Unit 1) was put into operation on April 26, 1964, and the second reactor (Unit 2) on December 29, 1967. Both reactors had similar dimensions and design. However, the flow diagram and the core arrangement were significanfly simplified in Unit 2 compared to that of Unit 1. Schematics and simplified layouts of the BNPP Units 1 and 2 are shown in Figs. A5.1 and A5.2. 

Based on the paper by Aleshchenkov, P.I., Zvereva, G.A., Kireev, G.A., Knyazeva, G.D., Kononov, V.I., Lunina, L.I., Mityaev, Yu.L, Nevskii, V.P., Polyakov, V.K., 1971. Start-up and operation of channel-type uranium-graphite reactor with tubular fuel elements and nuclear steam reheating. Atomic Energy (ATOMHaa Dneprua, Crp. 137—144) 30 (2), 163—170. 

Konovalova, O.T., Kosheleva, T.I., Gerasimov, V.V., Zhuravlev, L.S., Shchapov, G.A., 1971. Water-chemical mode at the NPP with channel reactor and nuclear steam reheat (In Russian). Atomic Energy 30 (2), 155—158. 

Technical Appendices, which provides readers with additional information and data on current nuclear power reactors and NPPs thermophysical properties of reactor coolants, thermophysical properties of fluids at suhcritical and critical/supercritical pressures, heat transfer and pressure drop in forced convection to fluids at supercritical pressures, world experience in nuclear steam reheat, etc. 

Transport of impurities to the core is also an issue. Tests in support of nuclear steam superheat reactors in the 1960s found that chloride deposition from the drying of moist steam resulted in heavy, adherent localized deposits [26] conducive to severe chloride-induced see of austenitic steels in the presence of oxygen and water. While Unit 2 at the Beloyarsk Nuclear Power Plant (a pressure-tube BWR with nuclear steam reheat channels) operated successfully for many years with a typical chloride concentration of 25 pg/kg [27], laboratory tests reported SCC of the stainless steel used for the channel elements (IKhlSNlOT) after temperature and pressure cycling in an environment containing chloride. 

Samoilov, A.G., Pozdnyakova, A.V., Volkov, V.S., 1976. Steam-reheating fuel elements of the reactors in the I.V. Kurchatov Beloyarsk nuclear power station. Atomic Energy (AxoMHaa OHeprna, cxp. 371—377) 40 (5), 451—457. 

With a few exceptions, coatings and linings are not used on the water and steam sides. In an EPRI project, about 50 turbine blade coatings have been evaluated, but none of these are being routinely applied. To reduce steam side oxidation in reheaters and superheaters, chromizing and chromating have been developed but these treatments are also not routinely applied. There is little use of composite materials with the exception of condenser tube sheets, which could be made of explosively clad stainless steel or titanium on carbon steel, and of the surfaces in the primary cycles of nuclear units where carbon or low alloy steels are protected by weld-deposited stainless steels. In pulp mill black liquor recovery boilers, stainless steel clad boiler tubes are often used. 

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