Chemical control of organic substances along water steam path of the power unit

The use of amino-containing reagents protects the heating surfaces of power equipment, as well as condensate and steam pipelines against corrosion both during operation of the equipment and standby mode. Currently, the ammonia-ethanolamine water regime of the second circuit is being implemented at most power units of the VVER-1000 NPP in Russia, which, compared with the traditional ammonia-water-chemical regime, causes an increase of chemical control and requires its optimization. Thus, the study under consideration is relevant. To control the water chemistry regime during the testing period at two VVER-1000 power units, the existing AHK system has been upgraded. “Leader APK” analyzers have been installed for automatic chemical control of the pH value, and electrical conductivity of direct and N-cationized samples with calculation of the concentration of an alkalizing agent (ammonia, ethanolamine). At the same time, the NPP staff have performed regular measurements of controlled water and steam quality parameters, supplemented by measurements of discrete organic chemicals using the IONEX liquid chromatograph. The authors have conducted instrument and manual analysis of water and steam quality indicators of two NPP units with VVER-1000 (2nd circuit); have calculated the components of the “total organic carbon” indicator and have analyzed their changes along the water steam path of unit No. 2. The use of the automatic analyzer “Leader APK” to control ammonia-ethanolamine water chemistry regime of the second circuit is proposed. An example of the calculation of the total concentration of alkalizing reagents is given. The possibility to maintain the pH of feed and boiler water within the normalized dosage limits of ethanolamine (or ethanolamine or ammonia) in feed water according to the standard scheme is shown. The calculation substantiates the possibility of operational control of the pH index, the total concentration of ammonia and ethanolamine in the feed water of the second circuit of the nuclear power plant unit with VVER.