Nuclear steam generators

Power plants based on the Rankine thermodynamic cycle have served the majority of the world s electric power generation needs in the twentieth century. The most common heat sources employed by Rankine cycle power plants are either fossil fuel-fired or nuclear steam generators. The former are the most widely used. 

Water Treatment. Water and steam chemistry must be rigorously controlled to prevent deposition of impurities and corrosion of the steam cycle. Deposition on boiler tubing walls reduces heat transfer and can lead to overheating, creep, and eventual failure. Additionally, corrosion can develop under the deposits and lead to failure. If steam is used for chemical processes or as a heat-transfer medium for food and pharmaceutical preparation there are limitations on the additives that may be used. Steam purity requirements set the allowable impurity concentrations for the rest of most cycles. Once contaminants enter the steam, there is no practical way to remove them. Thus all purification must be carried out in the boiler or preboiler part of the cycle. The principal exception is in the case of nuclear steam generators, which require very pure water. These tend to provide steam that is considerably lower in most impurities than the turbine requires. A variety of water treatments are summarized in Table 5. Although the subtieties of water treatment in steam systems are beyond the scope of this article, uses of various additives maybe summarized as follows ... 

At temperatures near the critical temperature, many organic degradation reactions are rapid. Halogenated hydrocarbons loose the halogen in minutes at 375°C (38). At temperatures typical of nuclear steam generators (271°C (520°F)), the decomposition of amines to alcohols and acids is well known (39). The pressure limits for the treatment of boiler waters using organic polymers reflect the rate of decomposition. 

Chatterjee, S.K. and Sharma, P.D. Review of Water Chemistry Treatment and Corosion Problems in Nuclear Steam Generators. Presented at the Bombay All India Symposium on Water Treatment. Indian Centre for Training and Development, November 1979. 

Nuclear steam cycles, 23 234-236 Nuclear steam generators, 23 217 Nuclear transfer, embryo cloning by, 12 451—452... 

A feature of corrosion studies which has been stressed recently (2) is the complete failure of laboratory tests on their own to predict how reliable operation of some nuclear steam generators can be maintained. At least a part of this problem is likely to arise from different redox and/or pH conditions imposed by the solution in autoclave tests and in plant conditions and many low level contaminants could be involved. In view of what has been said earlier concerning the role of Mo(VI) in stagnant water it is clear that some data, at least on the thermodynamics of aqueous Mo species, should be sought at high temperatures. 

The optimization of the large-capacity multistage flash evaporator was based on the consumption of the 370 thermal megawatts of energy available from the nuclear steam generator. It was necessary to determine the capital cost for various assumed terminal temperature differences and numbers of stages. Added to the amortized capital cost were all other costs necessary for operation of a complete plant, such as steam, labor, utilities, materials, and overhead. 

J. G. Collier, Nuclear Steam Generators and Waste Heat Boilers, in Boilers, Evaporators Condensers, S. Kakag (ed.), pp. 471-519, Wiley, New York, 1991. 

Table 2-2 Steam parameters for different nuclear steam-generating systems, from [10]... 

McKay, Mechanisms of Denting in Nuclear Steam Generators, presented during CORROSlON/82, Paper 214, March 1982, Houston, Texas. 

Experience with nuclear steam generators indicates that the probability of complete severance of a tube is remote. A double-ended rupture has never occurred in a steam generator of this design. The more probable modes of failure, which result in smaller penetrations, are those involving the occurrence of... 

R. Fischer and W. Bohmann, Concept for a Small Nuclear Steam-Generating System with an Integrated Construction, proceedings of a symposium on SmaU and Medium Power Reactors, Oslo, 1970 October 12-16, lAEA-SM-140/3, IAEA, Vienna, 1971, pp. 293-303. 

R. Garnsey [1979] Boiler Corrosion and the Requirement for Feed- and Boiler-Water Chemistry Control in Nuclear Steam Generators, Nucl. Energy 18, 117. 

Kovalenko W.K., Melnikov E.M., Mitenkov F.M., Movshevich S.M., Pologikh B.G., Khlopkin N.S., Yakovlev O.A. - Nuclear Steam Generating Plants of Ice-breakers and Their Operating Experience - Report to Hamburg Conference, 1979. 

The nuclear steam generating system (HTR-module) basically consists of ... 

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