Instrumentation for monitoring and control of water chemistry for light-water-cooled nuclear power plants

Based on the IAPWS technical guidance on ''Instrumentation for Monitoring and Control of Cycle Chemistry for Steam-Water Circuits of Fossil-Fired and Combined Cycle Power Plants,'' the latest situation regarding instrumentation for nuclear power plants is discussed. As a result of the discussion, it is concluded that: (1) Reliable and safe operation of plants is established by the application of suitable chemical conditions in plant cooling systems, which should be supported by the selection of suitable control targets for monitoring and by the application of reliable instruments. (2) The minimum level of key instrumentation consists of on-line as well as off-line instruments for monitoring the key parameters: - on-line: pH, conductivity, cation conductivity, O2 and H2 concentrations, electrochemical corrosion potential; - off-line: radioactive nuclides (60Co, 58Co, 131I, etc.), and the concentrations of metallic species (Fe, Cu, Co, etc.) and other species (B, Li, N2H4). (3) The application of high-temperature water chemistry sensors for in-situ measurement of cooling water properties and diagnosis of anomalous conditions based on monitored data is an important consideration for the future. (4) A technical guidance for nuclear plants, similar to the one issued for instrumentation and monitoring of chemistry in fossil-fired and combined-cycle plants, may be useful in the future, when common features could be combined in a unified guidance. (orig.)