Conditioning of water-steam-circuit of light and heavy water reactors

Abstract

The present invention relates to a method for dynamically controlling corrosion in a steam- water circuit of a nuclear power plant, the method comprising: injecting the compounds ethanolamine and optionally ammonia, the system comprising: injection units, located at a dosing point and configured for injecting the compounds ethanolamine and ammonia in the fluid circulating in the circuit; and measurement units, configured for measuring a value of the parameters pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit; the system being characterized in that it further comprises a control unit, the control unit comprising: a first acquisition module, connected to the measurement unit and configured for acquiring the measured values of the parameters and configured for acquiring at least one set-point value for said parameters; a command module, connected to the injection units and configured for commanding the injection of the compounds ethanolamine and ammonia by the injection unit as a function of the acquired at least one set-point value and measured values of the parameters, characterized in that ethanolamine is used as reducing agent. The present invention further relates to a system for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant.

Description

[0001]CONDITIONING OF WATER-STEAM-CIRCUIT OF LIGHT AND HEAVY WATER REACTORS Background The present invention concerns a method and system for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant. Nuclear power plants comprising a primary coolant circuit and a steam-water circuit separated from the primary coolant circuit are known. They are operated in particular by means of pressurized-water reactors or heavy-water reactors. Due to their construction and the materials used, the steam generators of nuclear power plants have to be operated under reducing conditions, which maintain a low oxygen concentration and thus avoid corrosion. Even during the plant's downtime it is required to protect susceptible materials on the secondary side of the steam generators from corrosion by adjustment of reducing conditions. This is also referred to as downtime preservation. For both establishing reducing conditions, for example hydrazine, methanol, or carbohydrazide are used as reducing agents for steam-water circuits of nuclear plants. During power operation of nuclear power plants, for example hydrazine causes the following reactions to occur in the steam-water circuit of nuclear power plants: x oxygen scavenging by the reaction N2H4+ O2--> N2+ 2H2O. The removal of the oxidant O2and, if applicable, of other oxidants such as copper ions facilitates the setting of reducing conditions.x reducing conditions by additional electrochemical hydrazine oxidation on the parts'surfaces according to the reaction N2H4+ 4OH- --> N2+ 4H2O + 4e-. Under standard conditions, the equilibrium electrode potential of this reaction is at room temperature - 330 mV against the hydrogen electrode. The reactions with hydrazine are thermally activated, causing a gradual transition from oxidizing to reducing conditions already in the condensate and feed water system of light- water and heavy-water reactors. When the feed water enters the steam generators and in the circulating water on the secondary side of the steam generators, hydrazine reacts with such a high rate that reducing conditions are ensured. In power plants operated with conventional energy sources specific oxidizing conditions are set in the condensate and feed water system using small amounts of oxygen. In so doing, the components' release of iron and thus also the introduction of corrosion products into the steam boiler is reduced. For this reason, the VGB standard for the quality of feed water, boiler water and steam in industrial power plants (VGB-S-010-T-00; 2011-12.DE) only recommends the AVT(O) (all volatile treatment with oxidation) operating mode, among the specified AVT operating modes, in which conditioning is performed only with ammonia, without adding any reducing agents. According to this standard, the AVT(R) (all volatile treatment with reduction) operating modes in which an additional volatile reducing agent is added as an oxygen scavenger should be used only in exceptional cases. Hydrazine is a very good oxygen scavenger. The known operation of the secondary steam- water circuit of pressurized-water reactors by adding hydrazine as a reducing agent thus corresponds to an AVT(R) operating mode. In hydrazine-containing media, the exact adjustment of the oxygen content in the circuit systems and thus an AVT(O) conditioning of the steam-water circuit systems of light-water and heavy-water reactors is not possible. In addition, hydrazine, as a strong reducing agent, can reinforce the erosion corrosion in the circuit systems. Some plants avoid the use of hydrazine by using less toxic carbohydrazide or methanol, however the use of ethanolamine as reducing agent in steam-water circuits of nuclear power plants has not been described or demonstrated yet in the prior art. CN 111362388 discloses a synergistic pH control method for introducing ethanolamine and ammonia in a two-loop thermodynamic system of a nuclear power plant, so as to meet the requirement that the pH of the two-loop thermodynamic system is 9.0 to 9.8. Thereby, the pH value of the two-loop thermodynamic system is effectively improved, the balance control is realized, the iron content of the two-loop thermodynamic system is obviously reduced, the corrosion condition of the two-loop thermodynamic system is improved, the corrosion of equipment of the two-loop thermodynamic system is reduced, the transport and deposition of corrosion products to a steam generator are reduced. Ammonia and ethanolamine are used for establishing the desired pH values and their concentrations and pH is monitored. EP 3 654 350 discloses a method for controlling the rate of corrosion of coolant loop equipment in nuclear power plants using corrosion inhibitors, whereby hydrazine is used as reducing agent and a combination of ammonia and organic amines such as ethanolamine is used as alkalizing agents and thus for establishing a desired pH value. DE 102015120722 discloses a nuclear power plant comprising a primary coolant circuit and a separate steam / water circuit, wherein a reductant other than hydrazine comprised of carbon, oxygen, and hydrogen, preferably methanol, is introduced in the secondary steam / water circuit. Said document refers to ethanolamine as an alkalizing agent only. It is an object of the invention to provide an effective, user-friendly and non-toxic corrosion protection in the secondary steam-water circuit of a nuclear power plant, in particular of a pressurized-water reactor or heavy-water reactor. Summary of the invention In order to solve the object, the present invention relates to a method for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant, the method comprising: - injecting the compounds ethanolamine and optionally ammonia in the fluid circulating in the circuit using injection units; and - measuring a value of the parameter pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit using measurement units; - acquiring the measured values of said parameters using an acquisition module connected to the measurement units; - acquiring at least one set-point value for said parameters using the acquisition module; - commanding the injection of the compounds ethanolamine and optionally ammonia by the injection units via a dosing point as a function of the acquired at least one set-point value and measured value of the parameters using a command module connected to the injection units, characterized in that ethanolamine is used as reducing agent. Preferably, the commanding of the injection of ethanolamine and optionally ammonia by the injection units via a dosing point is performed under further consideration of weighting factors for ethanolamine and optionally ammonia determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. Preferably, the acquisition module and the command module form a control unit. Preferably, the steam water circuit comprises a feed water container and the dosing point is located downstream from the feed water container. Preferably, the steam-water circuit comprises a main condensate pump and the dosing point is located downstream from the main condensate pump. Preferably, ethanolamine and ammonia are injected in the fluid circulating in the circuit using injection units. Preferably, further compounds are injected and wherein said further compounds are selected from methanol, hydrazine, and / or combinations thereof. Preferably, the concentration of the compounds in the steam-water circuit is continuously measured. Preferably, the steam-water circuit comprises a steam generator, wherein the steam generator has a circulation space, in which circulating water circulates to absorb heat from a primary coolant circuit. Preferably, the concentration of the compounds is measured in the circulating water. Preferably, the concentration of ethanolamine in the circulating water is from 1 x 10-8mol / kg to 1 x 10-3mol / kg and the concentration of ammonia in the circulating water is 3.5 x 10-3mol / kg or less. More preferably, the concentration of ammonia in the circulating water is 3.5 x 10-6to 3.5 x 10-3mol / kg. Preferably, the concentration of methanol in the circulating water is from 1 x 10-7mol / kg to1 x 10-3 mol / kg and / or the concentration of hydrazine in the circulating water is 6.25 x 10-7mol / kg or less. More preferably, the concentration of hydrazine in the circulating water is from 3 x 10-9mol / kg to 6.25 x 10-7mol / kg. Preferably, the steam-water circuit comprises a feed water portion and a main condensate portion. Preferably, the concentrations of the compounds are measured in the feed water portion and / or the main condensate portion. Preferably, a value of the parameters pH and redox potential in the circuit using measurement units is measured. Preferably, a value of the parameters pH and corrosion potential in the circuit using measurement units is measured. Preferably, a value of the parameters pH, redox potential, and corrosion potential in the circuit using measurement units is measured. Preferably, further parameters are measured and acquired and for which at least one set-point value is acquired, are selected from the group consisting of the concentrations of the compounds, the concentration of their decomposition products, and / or combinations thereof. Preferably, the parameters in the circuit using measurement units are continuously measured. Preferably, the parameters are measured in the circulating water. Preferably, the pH and the redox potential is measured in the circulating water. Preferably, the corrosion potential is measured on material surfaces. Preferably, the parameters are measured in the feed water portion and / or the main condensate portion. Preferably, the compounds act as an oxygen scavenger when exposed to gamma radiation. The problem is further solved by providing a system for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant using ethanolamine and optionally ammonia, the system comprising: - injection units, located at a dosing point and configured for injecting the compounds ethanolamine and optionally ammonia in the fluid circulating in the circuit; - measurement units, configured for measuring a value of the parameters pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit; the system further comprising a control unit, the control unit comprising: - a first acquisition module, connected to the measurement unit and configured for acquiring the measured values of the parameters and configured for acquiring at least one set-point value for said parameters; - a command module, connected to the injection units and configured for commanding the injection of the compounds ethanolamine and optionally ammonia by the injection unit as a function of the acquired at least one set-point value and measured values of the parameters, characterized in that ethanolamine is used as reducing agent. Preferably, the command module connected to the injection units is further configured for commanding the injection of the compounds ethanolamine and optionally ammonia by the injection unit under further consideration of weighting factors for ethanolamine and optionally ammonia determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. Preferably, the acquisition module and the command module form a control unit. Preferably, the steam water circuit comprises a feed water container and the dosing point is located downstream from the feed water container. Preferably, the steam-water circuit comprises a main condensate pump and the dosing point is located downstream from the main condensate pump. Preferably, ethanolamine and ammonia are injected in the fluid circulating in the circuit using injection units. Preferably, further compounds are injected and wherein said further compounds are selected from methanol, hydrazine, and / or combinations thereof. Preferably, the concentration of the compounds in the fluid circulating in the steam-water circuit is continuously measured. Preferably, the steam-water circuit comprises a steam generator, wherein the steam generator has a circulation space, in which circulating water circulates to absorb heat from a primary coolant circuit. Preferably, the concentration of the compounds is measured in the circulating water. Preferably, the concentration of ethanolamine in the circulating water is from 1 x 10-8mol / kg to 1 x 10-3mol / kg and the concentration of ammonia in the circulating water is 3.5 x 10-3 mol / kg or less. More preferably, the concentration of ammonia in the circulating water is 3.5 x 10-6to 3.5 x 10-3mol / kg. Preferably, the concentration of methanol in the circulating water is from 1 x 10-7mol / kg to 1 x 10-3mol / kg and / or the concentration of hydrazine in the circulating water is 6.25 x 10-7mol / kg or less. More preferably, the concentration of hydrazine in the circulating water is from 3 x 10-9mol / kg to 6.25 x 10-7mol / kg. Preferably, the steam-water circuit comprises a feed water portion and a main condensate portion. Preferably, the concentrations of the compounds are measured in the feed water portion and / or the main condensate portion. Preferably, a value of the parameters pH and redox potential in the circuit using measurement units is measured. Preferably, a value of the parameters pH and corrosion potential in the circuit using measurement units is measured. Preferably, a value of the parameters pH, redox potential, and corrosion potential in the circuit using measurement units is measured. Preferably, further parameters are measured and acquired and for which at least one set-point value is acquired, are selected from the group consisting of the concentrations of the compounds, the concentration of their decomposition products, and / or combinations thereof. Preferably, the parameters in the circuit using measurement units are continuously measured. Preferably, the parameters are measured in the circulating water. Preferably, the pH and the redox potential is measured in the circulating water. Preferably, the corrosion potential is measured on material surfaces. Preferably, the parameters are measured in the feed water portion and / or the main condensate portion. Preferably, the compounds act as an oxygen scavenger when exposed to gamma radiation. Detailed description of the invention Accordingly, the present invention relates to a method for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant, the method comprising: - injecting the compounds ethanolamine and optionally ammonia in the fluid circulating in the circuit using injection units; - measuring a value of the parameter pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit using measurement units; - acquiring the measured values of said parameters using an acquisition module connected to the measurement units; - acquiring at least one set-point value for said parameters using the acquisition module; - commanding the injection of the compounds ethanolamine and optionally ammonia by the injection units via a dosing point as a function of the acquired at least one set-point value and measured value of the parameters using a command module connected to the injection units, characterized in that ethanolamine is used as reducing agent. In addition, the present invention relates to a system for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant using ethanolamine and optionally ammonia, the system comprising: - injection units, located at a dosing point and configured for injecting the compounds ethanolamine and optionally ammonia in the fluid circulating in the circuit; - measurement units, configured for measuring a value of the parameters pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit; the system further comprising a control unit, the control unit comprising: - a first acquisition module, connected to the measurement unit and configured for acquiring the measured values of the parameters and configured for acquiring at least one set-point value for said parameters; - a command module, connected to the injection units and configured for commanding the injection of the compounds ethanolamine and optionally ammonia by the injection unit as a function of the acquired at least one set-point value and measured values of the parameters, characterized in that ethanolamine is used as reducing agent. The present invention has a number of advantages. The establishment of reducing conditions comprising no hydrazine or reduced amounts of hydrazine according to the present invention efficiently protects the metallic materials used in steam generators, which also allows maximum environmental and occupational safety compatibility and minimizes the chemicals required and the resulting reaction products. In addition, the present invention comprises no methanol or comprises reduced amounts of methanol. In addition, the strategies applied to date for water-steam cycle chemistry rely on the reducing agents hydrazine, carbohydrazide or methanol as well as on ammonia, ethanolamine or other alternative amines as alkalizing agents. Hydrazine, or carbohydrazide as a precursor of hydrazine, and methanol are toxic substances that pose a danger to humans and the environment. The process described in DE 102015120722 uses methanol to replace hydrazine as a substance on the REACH SVHC (Regulation on the registration, evaluation, authorisation and restriction of chemicals, Substances of very high concern) list, but requires much larger quantities due to its higher volatility. Methanol itself is also evaluated as a toxic substance. For both hydrazine and methanol, the situation is aggravated by the fact that the handling and use of these chemicals is strictly limited by legal requirements, so that in some cases hydrazine solutions, or methanol solutions, are only stored and handled at concentrations of up to 15% in the plants (toxicity, or fire load). In the process described in DE 102015120722, methanol does not lower the corrosion potentials as significantly as hydrazine or ethanolamine. Furthermore, when methanol is used as a reducing agent, significantly higher quantities are required due to the higher vapour volatility compared to hydrazine or ethanolamine, in particular to protect areas in the steam generator that are susceptible to corrosion and are in the liquid phase. Due to the toxicity of hydrazine, dispensing quantities were strictly limited, based on the Water Resources Act. As demonstrated in the examples of the present invention, the lowest corrosion potentials in the radiation field are achieved when ethanolamine is used. Corrosion protection is the main reason for the addition of conditioning chemicals. In this case, the use of ethanolamine represents a significant improvement in corrosion protection. Among other things, the use of ethanolamine can remove copper from the water-steam cycle. Compared to the process described in DE 102015120722, the use of ethanolamine has the advantage that the amount of ammonia required can be reduced or even avoided entirely, since ethanolamine is also an alkalizing agent. Also, a lower concentration of ethanolamine is required than would be the case for methanol alone, since the areas susceptible to corrosion come in contact in particular with the liquid phase and ethanolamine accumulates preferentially in the liquid phase. Preferably, in the method of the present invention, the commanding of the injection of ethanolamine and optionally ammonia by the injection units via a dosing point is performed under further consideration of weighting factors for ethanolamine and optionally ammonia determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency, Preferably, in the system of the present invention, the command module connected to the injection units is further configured for commanding the injection of the compounds ethanolamine and optionally ammonia by the injection unit under further consideration of weighting factors for ethanolamine and optionally ammonia determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. It is thus another advantage that the dynamic equilibrium according to the present invention enables to continuously adapt the amount of injected compounds, by continuously monitoring and acquiring the redox potential and pH of the fluid circulating and the corrosion potential of the construction materials in the steam-water circuit of a nuclear power plant. Further taken into account are relative weighting factors for the injected compounds determined based on the criteria toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. Preferably, the acquisition module and the command module form a control unit. The person skilled in the are is aware how to choose and implement a suitable acquisition module, command module, and control unit. Preferably, the steam water circuit comprises a feed water container and the dosing point is located downstream from the feed water container. Preferably, the steam-water circuit comprises a main condensate pump and the dosing point is located downstream from the main condensate pump. Suitably, for feeding the chemicals, either existing dosing points may be used, or an appropriate automated dosing station may be added, which for example may be installed after the main condensation pumps. Preferably, ethanolamine and ammonia are injected in the fluid circulating in the circuit using injection units. Preferably, further compounds are injected and wherein said further compounds are selected from methanol, hydrazine, and / or combinations thereof. In the present invention, ethanolamine is used as reduction agent as well as alkaline agent. Ammonia is used as an optional additional alkaline agent. Optionally, methanol and / or hydrazine may be used as an additional reduction agent. Preferably, in the method of the present invention, the commanding of the injection of ethanolamine and optionally ammonia by the injection units via a dosing point is performed under further consideration of weighting factors for ethanolamine and optionally ammonia and further for methanol, hydrazine, and / or combinations thereof, determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. Preferably, in the system of the present invention, the command module connected to the injection units is further configured for commanding the injection of the compounds ethanolamine and ammonia by the injection unit under further consideration of weighting factors for ethanolamine and optionally ammonia further for methanol, hydrazine, and / or combinations thereof determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. According to the present invention, weighting factors based on the above criteria for the individual compounds may be taken into consideration when determining their required amounts. The determination of the weighting factors, which are relative, depends on the priorities and country-specific regulations for the operation of the nuclear power plant in question. Some plants have quite strict criteria for water which can be disposed. The focus of other plants is on the best protection for their plants and have less focus on human and environmental protection. These constraints have to be discussed with each nuclear power plant operator and according to this assessment, weighting factors may be chosen. Irrespective of the selected weighting factors, two hard set-up limits for corrosion protection must be fulfilled, which are pH and measured potentials. Exemplary set-point values are pH ^ 9.5 and potentials (i.e. corrosion and / or redox) at 280°C ^ - 100 mVSHE. (i.e. measured with a standard hydrogen electrode, SHE) The relative weighting factors are obtained by the multiplication of the weightings of the individual compounds for each criterion considered (for reducing condition or alkalization condition) and then set into relation as a matter of percentage. The result would be a percentage share, which means reducing conditions should be established by e.g. 80% ethanolamine and 20% methanol. Alkalization should be established by 20 % ethanolamine and 80% ammonia. This distribution may be double checked for other parameters, e.g. concentration of decomposition products in the media, etc. The relative weighting factors are thus calculated from the weightings previously made for each compound and criterion depending on the plant operators preferences. A substance is to be weighted highly if it achieves the plant-specific objectives to a high degree. Toxicity: The weighting factors for toxicity take into account the hazards of the pure, undiluted chemical in accordance of the MSDS (material safety data sheet), such as toxic, mutagenic, cancerogenic. For example, hydrazine is toxic, cancerogenic and mutagenic, methanol is moderately toxic, ethanolamine has none of these three hazards. Weighting for toxic hydrazine = 1, for methanol and ethanolamine = 10, respectively (high weighting means that this substance should be preferably used) IEX (ion exchange) fouling: Takes into consideration the effect of the chemical on ion exchange resins used in the water steam circuit (e.g. condensate purification system, blow- down purification system^^«^^H[FOXGLQJ^DQ^DOUHDG\^GHILQHG^KDUG^FULWHULRQ^^H^J^^,(;^GRHV^QRW^ comply with an ethanolamine concentration of ^ 3.0 ± 4.5 ppm by mass). For example, morpholine damages IEX resins, ethanolamine damages IEX resins only if the concentration is higher than 3 ppm by mass, methanol ± no damage of IEX resins is known, ammonia and hydrazine ± no damage of IEX resins is known => weighting for ammonia, hydrazine = 10, for methanol and ethanolamine ^ 3 ppm by mass = 5, morpholine = 10. Water compatibility / environmental compatibility: National waste water laws define concentration of chemicals and substance groups in wastewater (water in the water steam circuit is continuously disposed and the water steam circuit is refilled with new conditioned water); besides hard criteria (e.g. hydrazine ^ 2 ppm by mass), the weighting may be lowered from 10 to 5 or 1, if the concentration of the conditioning reagent in the wastewater is significant in accordance with the national waste water laws. Another point influencing the weighting factor is the classification in the MSDS (material safety data sheet; high water hazard, medium water hazard, low water hazard). For example, the weighting factor may be defined under consideration of the respective national or regional waste water laws, e.g. the German waste water law, which is further specific for each federal state. Decomposition products: The weighing factor for decomposition products is mainly focusing on organic compounds produced by oxidation of organic conditioning agents. If the organic conditioning agent is sensitive to heat, almost the complete conditioning agent is decomposed in the hot parts of the water steam circuit resulting in high conductivity (conductivity is limited in the water steam cycle) and detrimental compounds for turbine condenser tubing materials. For example, morpholine decomposes rather quickly resulting in formic and acetic acid damaging the turbine blades or ammonia may result in generation of nitrates also damaging the turbine blades. Alkalisation efficiency: this weighing factor takes into account the basicity constant of the conditioning agent as well as the distribution between steam and liquid phase. For a good corrosion protection, the pH of the liquid phase is crucial. For example, ammonia has a lower basicity constant but a higher distribution into the steam phase than ethanolamine. Reductive Efficiency: The weighing factor takes into account the open circuit potentials, which are set by addition of the respective compound as well as the distribution between steam and liquid phase. For a good corrosion protection, the distribution into the liquid phase is crucial. Furthermore, it takes into account the reductive efficiency outside the steam generator (lower temperature, no radiation field) and the reaction rate with oxygen. The simplest way to set the weighing for an individual compound is a three score principle, Good / highly preferred / highly suitable = 10, Medium / medium suitable = 5 and Bad / not preferred / less suitable = 1. %\^WKLV^³VFRULQJ´ principle, it is possible to consider plant specific requirements / preference as well as criteria ensuring a high corrosion protection and low detrimental effects for the system. For pH adjustment or alkalization, with ethanolamine pH values around 9.9 or higher, for example, cannot be achieved. Ethanolamine can also be somewhat unfavourable in terms of plant compatibility, since in the case of appropriate continuous operation of the purification of the steam generator blowdown, for example the ion exchangers are used up more quickly or age more quickly. However, ethanolamine has highly advantageous reducing properties and is suitable if the focus of the operator of the nuclear power plant in question is on high occupational safety and high environmental compatibility. As with most compounds there is a trade-off between advantages and disadvantages and the person skilled in the art will choose ethanolamine as a reducing agent if suitable for their needs. Table 1 shows weightings assumed based on the importance of the individual weighting factors and the properties of the individual compounds, respectively. Exemplary weightings for ethanolamine, ammonia, methanol and hydrazine for each criterion, which may be used to calculate the relative weighting factor, are indicated. An arbitrary scale of 1 to 10 was used, wherein 1 is the least desired and 10 is the most desired. Table 1 As already mentioned above, hydrazine and methanol, which require high occupational safety standards have been given a weighting of 1 when considering the criterion occupational safety, whereas ammonia and ethanolamine, which have low toxicity have a favourable weighting of 10. In terms of the criterion of effectiveness of alkalization, ammonia is an effective alkalizing compound and has a weighting of 10, whereas the weighting of methanol and hydrazine is 1, since their alkalization effectiveness is low, and so on. If the weightings for the individual criteria from Table 1 are used, the following relative weighting factors may be obtained for ethanolamine and ammonia: Ethanolamine: 10 (toxicity) * 10 (water compatibility) *5 (degradation products) *5 (component compatibility) * 5 (alkalization efficacy) = 12,500 Ammonia: 10 (toxicity) * 5 (water compatibility) *10 (degradation product) *10 (component compatibility) *10 (alkalization efficiency) = 50.000 The final proportions for the individual components to be used based on the relative weighting factors may then be calculated as follows as percentages (to calculate the proportion, the determined weighting factor must be divided by the sum of all weighting factors required for the task): Proportion (ethanolamine) for alkalization = 12,500 / (50,000 + 12,500) = 20%. Proportion (ammonia) for alkalization = 50,000 / (50,000 + 12,500) = 80% Thus, to achieve pH ^ 9.5 the contribution of ammonia on the pH should be 4 / 5 and the contribution of ethanolamine on the pH 1 / 5. The system determines the current pH, determines the missing OH concentration, calculates the OH ions resulting from the feed of ammonia, respectively ethanolamine and then adjusts the quantity to be dosed in such a way that 4 / 5 of the OH ions come from the feed of ammonia and 1 / 5 from the feed of ethanolamine. Figure 1 further highlights how the pH depends on the amounts of ethanolamine and ammonia. From an ethanolamine concentration of more than 4.5 ppm by mass, disadvantages for the ion exchangers in the purification systems may be assumed (blowdown purification system, condensate purification system). Figure 1 also highlights that pH values of 9.9 or higher may by only achieved by using ammonia only The considered relative weighting factors for ethanolamine and optionally ammonia determined are based preferably on at least three, more preferably at least four, even more preferably at least five criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. Most preferably, the considered relative weighting factors for ethanolamine and optionally ammonia determined are based on the criteria toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency. Generally, the weighting factor may be determined as follows: Wfi: Weighing factor i from 1 to x, x = number of used conditioning agents, j from 1 to y, y =number of used criteria ^^:IRi, max = product of maximal values for each criterion WfRi,i: relative weighing factor for used chemical for used criteria WfR1 = WfR1,1 * WfR1,2 ^««^^:IR1,z = product of relative weighing factor for one used chemical for all used criteria Wfi = (WfRi,1 * WfRi,2 ^««^^:IRiz^^^^^^:IRi, max Preferably, the concentration of the compounds in the fluid circulating in the steam-water circuit is continuously measured. Preferably, the steam-water circuit comprises a steam generator, wherein the steam generator has a circulation space, in which circulating water circulates to absorb heat from a primary coolant circuit. Preferably, the concentration of the compounds is measured in the circulating water. Preferably, the concentration of ethanolamine in the circulating water is from 1 x 10-8mol / kg to 1 x 10-3mol / kg and the concentration of ammonia in the circulating water is 3.5 x 10-3mol / kg or less. More preferably, the concentration of ammonia in the circulating water is 3.5 x 10-6to 3.5 x 10-3mol / kg. Preferably, the concentration of methanol in the circulating water is from 1 x 10-7mol / kg to 1 x 10-3mol / kg and / or the concentration of hydrazine in the circulating water is 6.25 x 10-7mol / kg or less. More preferably, the concentration of hydrazine in the circulating water is from 3 x 10-9mol / kg to 6.25 x 10-7mol / kg. The concentration of ethanolamine can be controlled by pH as a function of ammonia concentration, when only ammonia and ethanolamine (ETA) are used for alkalization. On the other hand, the amount of ethanolamine can be determined unambiguously by ion exchange chromatography. Further, commercial TOC (total organic content) flow analyzers can also be used to determine the ethanolamine concentration (in the absence of other organic compounds, such as methanol), which also have continuous measurement capability. The concentration of methanol can be measured continuously via commercially available TOC flow analyzers as a function of ethanolamine concentration. Ammonia and hydrazine concentrations in water-steam cycle systems may be determined by photometric measurements, or automated flow-through photometers. Flow analyzers are also available that are already calibrated for certain compounds (e.g. methanol analyzers) or can be calibrated. Further there is the possibility to determine compound concentrations discontinuously by high pressure chromatography. Preferably, a value of the parameters pH and redox potential in the circuit using measurement units is measured. Preferably, a value of the parameters pH and corrosion potential in the circuit using measurement units is measured. Preferably, a value of the parameters pH, redox potential, and corrosion potential in the circuit using measurement units is measured. Preferably further parameters measured and acquired and for which at least one set-point value is acquired, are selected from the group consisting of amount of dissolved oxygen, the concentrations of the compounds, the concentration of their decomposition products, and / or combinations thereof. Commercially available pH measurement sensors may be used for continuous monitoring of the pH value in steam-water cycle systems. To monitor the oxygen content in the water-steam cycle systems of pressurized and heavy water reactors, oxygen or the pH value in the main condensate and / or feed water is measured online, i.e. continuously. For this purpose, commercially available oxygen sensors with very high measurement accuracy (ppb range, ^ 0.1 ppb by mass), or corresponding pH value sensors are used. The digital measured values can be used as input measured values for an automated dosing system. Redox and corrosion potentials in the circuit of nuclear steam generators can be determined by means of potential measurements and suitable reference electrodes. Preferably, the set-point or limit for the measured redox and / or corrosion potentials in the steam-water circuit is E (280°C) ^ -100 mV, that is, the potentials ^ -100 mV or lower at 280°C, more preferably E (280°C) ^ -200 mV, even more preferably E (280°C) ^ -300 mV. Preferably, the set-point or limit for the pH in the steam-water circuit, in particular in the feed water, is pH (25°C) ^ 9.5, that is, the pH is 9.5 or higher, more preferably pH (25°C) ^ 9.8, even more preferably pH (25°C) ^ 9.9. Preferably, the set-point or limit for the hydrazine concentration in the circulating water is 6.25 x 10-7mol / kg or less, preferably 4.6 x 10-7mol / kg or less, more preferably 3 x 10-7mol / kg or less. Preferably, the set-point or limit for the dissolved O2concentration in the steam generator, is DO (dissolved oxygen) ^ 20 ppb by mass, that is, the dissolved oxygen concentration is 20 ppb by mass or less, more preferably DO ^ 5 ppb by mass, even more preferably DO ^ 2 ppb by mass, even more preferably DO ^ 1 ppb by mass. Accordingly, in case certain conditions are to be maintained, the following exemplary solution matrixes are to be solved according to the presenW^LQYHQWLRQ^^³Wf´^LV^WKH^SURGXFW^RI^ all relative weighing factors of one compound, ETA is ethanolamine. w(ETA) * Wf(ETA) / Wf(ETA) * Wf(NH3) + w(NH3) * Wf(NH3) / Wf(ETA) * Wf(NH3), where w is the part of contribution on alkalization and the target pH value is above the hard set-up limit of pH ^ 9.5. where v is the part of contribution on the effect on reducing conditions and the target redox and / corrosion potential values are - 100 mV or less, so that e.g. one or more of the following conditions are met: potential E (280°C) ^ -300 mV dissolved O2 ^ 5 ppb by mass N2H4 ^ 20 ppb by mass (^^6.25 x 10-7mol / kg) or at least N2H4 ^ 10 ppb by mass (^^3 x 10-7mol / kg) As indicated above, the parameters may be continuously measured. Based on the continuously monitored and recorded parameters, the required amount of compounds to be dosed is continuously re-calculated and adjusted. The required amount of compounds to be dosed is continuously re-calculated and adjusted under further consideration of the weighting factors. Preferably, the monitoring and acquisition of the individual parameters and set-points, the monitoring of the concentrations of the individual compounds, the calculation of the required amounts of compounds, and the dosing of the compounds is automated. Preferably, an automatic dosing system is used, which automatically retrieves collected online and discontinuous data and uses them to calculate the dosing quantities. However, this places demands on the electronic data of measured values as well as the laboratory information management system of the respective plants. Simplifications for this could be provided by separate software that records data automatically / manually and this is then either used to set the dosing quantities manually or is in turn transferred to an automatic dosing system. Based on the specified starting concentration of ethanolamine and methanol, the specified general conditions (e.g., hydrazine-free, O2content, open circuit potential, etc.), the dosing of ethanolamine would have an effect on the dosing amounts of hydrazine and ammonia and would result in the need to reduce these dosing amounts. As each conditioning chemical has an effect on another, a dynamic equilibrium will be established over time, which would also be very flexible to any other changes in the water / steam cycle (e.g., changing air intake, fouling in the steam generator, etc.). The system may be further simplified, at the expense of optimization, by defining the dosing amount of methanol and / or ethanolamine. According to the control and diagnostic parameters, this would result in a corresponding effect on ammonia, or possibly hydrazine. Preferably, the compounds, in particular ethanolamine and optionally further methanol and / or hydrazine, act as an oxygen scavenger when exposed to gamma radiation. As the oxygen scavenging is only induced by the gamma radiation present in the steam generator, the oxygen content in the steam-water circuit can be exactly adjusted, thus allowing for an AVT(O) operating mode to be used in the steam-water circuit of the light- water or heavy-water reactor. Brief description of the drawings Figure 1 illustrates the pH depending on the amounts of ethanolamine and ammonia in the circuit. Figure 2 illustrates the influence of hydrazine, methanol, formaldehyde and ethanolamine on the oxygen concentration at the inlet and at the outlet of the test solution and the course of potentials (redox potential) of platinum and four typical steam generator construction materials in a test loop in continuous operation, whereby the timeframe of 1750 to 2750 hours, i.e. 1000 hours, is shown (the redox potential of platinum and the oxygen concentrations are repeated in each graph): (a) redox potential of stainless steel 1.4541 (SS); (b) redox potential of Alloy 800 which was preoxidized before test start; (c) redox potential of Alloy 800; (d): redox potential of Alloy 690TT. Figure 3 illustrates the test loop experiment; (a) schematic set-up of the autoclave (b) calculation of energy dose rate (DL) for 16 distances (Fit Function); (d) autoclave geometry; (e) autoclave clustering in 236 clusters. Figure 4 illustrates a schematic view of a steam-water circuit in a nuclear power plant. Examples Figure 2 shows the redox potentials of platinum, stainless steel 1.4541 (SS), Alloy 800 preoxidized Alloy 800 and Alloy 690TT at steam generator conditions (T = 280°C, pH = 9.5) in a test loop in continuous operation. The compound amounts and the time frames in which they were used are indicated in Figure 2. Figure 2 also highlights the presence or absence of a radiation field. The more negative the measured corrosion potentials, the higher the corrosion protection effect, or the potential for reducing conditions on the material surfaces. A distinction is made between two borderline cases: full power of the steam generator with a corresponding radiation field and no radiation field. For steam generators, redox potentials are specified in relevant water chemistry guidelines. The redox potential is understood to be the open circuit potential of platinum, which is meaningful for the corrosion potential when Ag / AgCl electrodes are used as reference electrodes. Corrosion potentials are understood to be the open circuit potentials of the construction materials used, such as Alloy 800 or Alloy 690. The test loop as schematically shown in Figure 3 consists of a heated autoclave and simulates conditions in a steam generator. The autoclave is a reservoir for alkalized demineralized water comprising injection points for dosing different reducing agents and sensors for monitoring pH, dissolved oxygen, and conductivity. Ammonia or ethanolamine was used as alkalizing agent. The reducing agent (methanol, formaldehyde, hydrazine or ethanolamine) was continuously injected directly upstream of the autoclave by a high pressure liquid chromatography (HPLC) pump. The injected chemicals were additionally degassed. The injection rates of the reducing agents varied between 0.2 mL / min and 0.5 mL / min. Demineralized water was preconditioned, i.e., alkalized to pH of 9.5 to 10, degassed, and then exposed to 20 ppb by mass oxygen. Immediately before the warm-up section, the required concentration of reducing agent was dosed in. The dissolved oxygen in the medium was determined before the dosing point. Oxygen concentration was determined using commercially available oxygen sensor located in the medium flow downstream and upstream the autoclave and measured at 25°C. The medium was heated to 280°C in a warm-up section upstream of the autoclave (not shown) and was present in 1-phase, i.e. liquid form. The flow rate through the 2 Liter stainless steel autoclave was 8 L / h. In the stainless steel autoclave, coupons of different material samples were arranged in a ring around an immersion tube located in the centre of the autoclave. A gamma source Cs-137 with an activity of up to 3.7E11 Bq was inserted into this immersion tube, exposing the autoclave medium to radioactive radiation. The average energy doses rate was 5.9 Gy / h. The gamma emitter is stored in a shielded container and was manually and remotely transferred in and out of the test autoclave. More specifically, the energy dose rate, as well as the deposited gamma energy in the autoclave vessel, from the gamma emitter, was estimated by using Monte-Carlo Program MicroShield V9.06 as shown in Figure 3(b). Sixteen different distances were considered, taking into account dose buildup, attenuation by the respective upstream water layer (100 bar / 280°C) and absorption of the source housing, immersion tube and extension tip. The autoclave volume as shown in Figure 3(c) was divided into 1 cm² clusters as shown in Figure 3(d) and the absorbed dose rates for the 236 clusters with their individual distance to the gamma source were calculated. The average energy doses rate was 5.9 Gy / h considering the 236 clusters. This is equivalent with a deposited gamma energy of 564 Joule for the typical exposition time of approximately 65 hours. The calculation based on the following values: Water volume in the autoclave: 1958 cm³ Density of water at 100 bar / 280°C: 0.756 g / cm³ Water mass in the autoclave: 1.48 kg After leaving the stainless steel autoclave, the medium was brought back to room temperature and the dissolved oxygen and pH were measured. All parameters, conductivity (LF) out, conductivity in, dissolved oxygen (DO) out, DO in, temperature out, temperature in, pH (25°C) out and pH (25°C) in, were monitored and documented by a data logger. An external cooled Ag / AgCl electrode is used as reference electrode. A platinum coupon is used for measuring the redox potential of the fluid. The working electrodes for measurement of the corrosion potentials are coupons of typical steam generator construction materials. They are made of austenitic stainless steel (1.4541), Alloy 800 oxidized, Alloy 800 and Alloy 690TT. From Figure 2 it can be seen that ethanolamine in the radiation field causes the lowest corrosion potentials of the tested steam generator materials, even lower values than with the widely used and proven hydrazine; CH2O (formaldehyde) was chosen as a further representative C,H,O compound and which has better reducing properties than methanol. It is evident that ethanolamine induces the best reducing conditions on steam generator material surfaces both in the radiation field and without the radiation field. Ethanolamine has not been described as an effective reducing agent in nuclear facilities to date. This results in the application case that in the simplest application ethanolamine and ammonia are sufficient to build up a comprehensive corrosion protection in the water-steam cycle of a nuclear power plant. In the extended application, the conditioning chemicals can be supplemented by methanol and, if necessary, hydrazine. The required concentration ratios are determined and adjusted dynamically and weighted according to other criteria. For example, a conditioning chemical can be weighted low or left out of consideration if corresponding regulations exist. For example, there are country-specific regulations regarding the water quality that can be taken into consideration, i.e. freedom from hydrazine, TOC limits, etc., or also operator specifications regarding the most economical mode of operation, i.e. with the lowest costs. Here, the required quantities and this includes the efficiency for conditioning as well as the costs per quantity have to be specified, which results in a corresponding weighting. Dynamic equilibria can best be controlled with appropriate data acquisition and data processing, so that ideally computer-controlled systems are used for the acquisition and processing of measured values. If, for example, the measuring system detects an increase in oxygen in the system due to a condenser leak, for example, the system calculates adjusted concentrations without delay, i.e. first the reducing agents used may be adjusted according to the weighting; then it may be checked whether this has an influence on the pH value and the alkalization values may also be adjusted accordingly. Before a concentration can be changed, however, it may be checked whether a hard criterion (e.g. maximum concentration in the wastewater) or a weighting permits this at all. The result is a plant-optimized combination of all conditioning chemicals that reacts ad hoc to changes in the water-steam cycle. Example 2 In Figure 4, a nuclear power plant 10 comprising a primary coolant circuit 12 and a steam- water circuit 14 separated therefrom is shown which comprises a reactor 16 through which the primary coolant circuit 12 flows, and a steam generator 18, a condenser 20 and a feed water container 22 in the steam-water circuit 14. Preferably, the reactor 16 is a pressurized-water reactor. The heat generated in the reactor 16 is conveyed via the primary coolant circuit 12 to the steam generator 18 where it is transferred to the steam-water circuit 14. In a first high-pressure turbine 24 and in a second low-pressure turbine 26 the thermal energy of the hot water vapour is converted into kinetic energy which is finally used to drive generators (not shown) and thus to generate electrical energy. In the condenser 20 the cooled water vapour is transferred into its liquid phase forming the main condensate. To this end, the condenser 20 is cooled by a cooling water supply line 28 and the warm waste gases are discharged via air suction pump in the condenser 30. Losses are compensated for by a balance water supply line 32. The main condensate is conveyed from the main condensate portion 34 leading from the condenser 20 to the feed water container 22 via a main condensate pump 36 into the feed water container 22. In the feed water container 22 the main condensate as well as water from a water separator 38, located between the high-pressure turbine 24 and the low- pressure turbine 26, are collected and maintained for supply to the steam generator as feed water. In the feed water portion 40 leading from the feed water container 22 to a feed water supply line 54 at the steam generator the feed water, by means of a feed water pump 42, is pumped back into the steam generator 18 where it is reused to absorb heat and the secondary steam-water circuit 14 is closed. In the feed water portion 40, between the feed water container 22 and the feed water pump 42, a dosing point 44 is located, where ethanolamine is introduced into the steam-water circuit 14 by means of a dosing device 46. In the steam generator 18, the reducing agent is exposed to gamma radiation and acts as an oxygen scavenger. An apparatus 50 to continuously measure the concentration of the reducing agent and the redox potential is provided in the circulation space 48 of the steam generator. To this end, the apparatus 50 comprises a potential sensor 58. As an alternative or in addition, the concentration of the reducing agent in the circulating water can be continuously measured by means of a TOC flowmeter 56 in a sampling line 60 leading out of the steam generator 18. Moreover, the feed water supply line 54 can be additionally provided with a sampling line 61 upstream from the steam generator 18 to perform measurements by means of a TOC flowmeter 56 and / or a potential sensor 58. Intermediate heaters 52 are located between the water separator 28 and the low-pressure turbine 26 as well as in the main condensate portion 34 and the feed water portion 40 which are used to return released thermal energy back into the steam-water circuit 14. In the following, the method for operating the nuclear power plant 10 is described by the example of a 1000 MW plant using ethanolamine as a reducing agent. For the start-up and power operation of the reactor 16 an ethanolamine concentration of 3 ^g / kg to 10 mg / kg is set in the circulating water of the steam generator. The ethanolamine concentration set for the feed water is 2 to 3 times higher to compensate for losses caused by adsorption on the surfaces of the steam-water circuit. For downtime preservation, an ethanolamine concentration of 1 x 10-8to 5 x 10-2mol / kg is provided in the steam generator. The daily amount of ethanolamine that has to be supplied during power operation to obtain a corresponding concentration depends on the plant output and is here in the range from 16 kg / d to 41 kg / d. Thus, in the case of a conventional reducing agent tank having a tank volume of 1500 L one tank filling is sufficient to convey ethanolamine into the steam-water circuit 14 for several weeks before the tank has to be refilled. Due to the higher feed water flows, the amounts of ethanolamine for a 1300 MW plant are elevated by approximately 25 percent. The injection of ethanolamine into the steam-water circuit allows to adjust oxidative conditions in the steam-water circuit 14 outside of the steam generator 18 (AVT(O) operating mode), with the oxygen concentration in the steam-water circuit 14 being maintained at less than 0.1 mg / kg according to the VGB standard. In addition, a pH of 9.5 or more is set in the steam-water circuit 14. The alkaline pH is further set by using ammonia. Preferably, the ethanolamine is introduced into the steam-water circuit 14 downstream from the feed water container 22 at the dosing point 44 by means of the dosing device 46 as part of the ethanolamine is lost by adsorption on surfaces in the steam-water circuit, thus allowing for the ethanolamine used to be available from dosing start. In an embodiment (not shown) of a nuclear power plant 10 without a feed water container 22 it can be advantageous to choose, instead of the dosing point 44, an alternative dosing point, for example directly upstream from the steam generator 18 or directly downstream from the water separator 38. It is also possible that several dosing points 44 are provided in the steam-water circuit 14. As a rule, the most suitable dosing point 44 for the respective plant should be determined together with the operator. To measure and adjust the concentration of ethanolamine in the steam-water circuit 14 the oxygen content in the main condensate of the main condensate portion 34 and in the feed water of the feed water portion 40 is monitored. To this end, continuous measurements using commercially available sensors with a measuring accuracy in the ppb range (^g / kg) are performed. As this measurement method is continuous, the measured signals can be used as an input parameter for process control. The concentration of ethanolamine, however, is measured continuously in the feed water and in the circulating water circulating in the circulation space 48 of the steam generator 18 by means of commercially available TOC flowmeters 56 via sampling lines 60, 61. Preferably, these continuous measurements can be complemented by additional discontinuous analytical methods, which, for example, can be used to differentiate between various organic compounds. Commercially available analytical devices and analytical methods also allow for the continuous measurement of the concentration of ethanolamine having a reducing effect when exposed to gamma radiation both in the circulating water and in the feed water. Experience with industrial plants shows that, in conventional steam boilers, ethanolamine is thermally stable even at temperatures of up to 530° C. and pressures of 270 bar. If, however, oxidants are present as well in the conventional steam boilers, an oxidative decomposition of ethanolamine takes place. The purely thermal decomposition of ethanolamine in the circulating water of steam generators 18, however, is negligibly small, which allows for the concentration of the ethanolamine in the feed water necessary for the plant's respective operating state to be adjusted and controlled based on the current ethanolamine consumption in the steam generator. Thus, the current ethanolamine consumption in the steam generator 18 through oxygen scavenging and other radical reactions is determined by continuous measurements taking place in the circulating water and feed water. The total ethanolamine turnover in the steam generator 18 is basically composed of two components: (1) radiolytic decomposition by the gamma radiation acting on the secondary side of the steam generator 18 (metabolic rate); (2) radiation-induced oxidative ethanolamine decomposition by oxygen or other oxidizing substances in the steam generator 18 such as copper ions and copper oxides or trivalent iron oxides and hydroxides. The oxygen introduction into the steam generator 18 is known from the continuous measurement of the oxygen content in the main condensate and in the feed water. By evaluating operating phases with an elevated oxygen content or by specifically increasing the oxygen content in the feed water the ethanolamine consumption by radiation-induced oxidation can be exactly determined and adjusted such that reducing conditions in the steam generators 18 are always guaranteed. This allows to adjust oxidative conditions in the steam-water circuit 14 outside the steam generators 18 (AVT(O) operation) and to simultaneously ensure reducing conditions in the steam generators 18 (AVT(R) operation). If, for example, a rapid and significant increase in the oxygen concentration is registered in the main condensate and in the feed water, the concentration of the reducing agent in the feed water and thus the ethanolamine turnover in the steam generator can be immediately increased by this adjustment. The dosing of ethanolamine and optionally further methanol, is started with a feed water concentration of 200 ppb by mass during power operation. Either a newly installed automatic dosing system can be used for dosing the conditioning chemicals, or the hydrazine dosing station can be used alternately by means of a 2-way distributor for dosing ethanolamine and methanol, since hydrazine dosing is terminated at this point. For chemical monitoring of the process, continuous TOC analyzers are installed in the sampling system for feed water and circulating water, as well as a potential measurement in the circulating water of all steam generators. The monitored chemical parameters are either transferred to the automatic dosing system (active connection to the I&C network), or entered into a special software to calculate the required conditioning chemicals (autarkic mode of operation). The newly calculated dosing quantities are set automatically, or are to be stored in the system. The required daily quantity of ethanolamine is initially 35 kg per day. With each new measured value for a monitored chemical parameter, this quantity will be reduced, in some cases significantly, until the criteria for optimized operation are reached. The amount of ammonia will also need to be reduced or adjusted over time. By monitoring the parameters open circuit potential in the steam generator circulating water, or on the steam generator materials, as well as the oxygen concentration in the steam generator circulating water, reducing conditions in the steam generators are thus ensured. The continuous measurement of the TOC value in the circulating water enables the determination of the total methanol and ethanolamine consumption in the steam generator. It is composed of: (1) adsorption on the surfaces, (2) fraction due to oxidative degradation by oxygen or other oxidizing substances in the steam generator, such as copper ions and copper oxides or trivalent iron oxides and hydroxides, and (3) radiolytic degradation by the incident gamma radiation.

Claims

CLAIMS 1. Method for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant, the method comprising: - injecting the compounds ethanolamine and optionally ammonia in the fluid circulating in the circuit using injection units; - measuring a value of the parameter pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit using measurement units; - acquiring the measured values of said parameters using an acquisition module connected to the measurement units; - acquiring at least one set-point value for said parameters using the acquisition module; - commanding the injection of the compounds ethanolamine and optionally ammonia by the injection units via a dosing point as a function of the acquired at least one set-point value and measured value of the parameters using a command module connected to the injection units, characterized in that ethanolamine is used as reducing agent.

2. The method of claim 1, wherein commanding the injection of ethanolamine and ammonia by the injection units via a dosing point is performed under further consideration of weighting factors for ethanolamine and ammonia determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency, 3. The method of claim 1 or 2, wherein the acquisition module and the command module form a control unit.

4. The method of any of claims 1 to 3, wherein the steam water circuit comprises a feed water container and the dosing point is located downstream from the feed water container.

5. The method of any of claims 1 to 4, wherein the steam-water circuit comprises a main condensate pump and the dosing point is located downstream from the main condensate pump.

6. The method of any of claims 1 to 5, wherein further compounds are injected and wherein said further compounds are selected from methanol, hydrazine, and / or combinations thereof.

7. The method of any of claims 1 to 6, wherein the concentration of the compounds the in the fluid circulating in the steam-water circuit is continuously measured.

8. The method of any of claims 1 to 7, wherein the steam-water circuit comprises a steam generator, wherein the steam generator has a circulation space, in which circulating water circulates to absorb heat from a primary coolant circuit.

9. The method of claim 8, wherein the concentration of the compounds is measured in the circulating water.

10. The method of any of claims 1 to 9, wherein the concentration of ethanolamine in the circulating water is from 1 x 10-8mol / kg to 1 x 10-3mol / kg and the concentration of ammonia in the circulating water is 3.5 x 10-3mol / kg or less, preferably, the concentration of ammonia in the circulating water is 3.5 x 10-6to 3.5 x 10-3mol / kg.

11. The method of any of claims 6 to 10, wherein the concentration of methanol in the circulating water is from 1 x 10-7mol / kg to 1 x 10-3mol / kg and / or the concentration of hydrazine in the circulating water is 6.25 x 10-7mol / kg or less, more preferably, the concentration of hydrazine in the circulating water is from 3 x 10-9mol / kg to 6.25 x 10- 7 mol / kg.

12. The method of any of claims 1 to 11, wherein the steam-water circuit comprises a feed water portion and a main condensate portion.

13. The method of claim 12, wherein the concentrations of the compounds are measured in the feed water portion and / or the main condensate portion.

14. The method of any of claims 1 to 13, wherein further parameters measured and acquired and for which at least one set-point value is acquired, are selected from the group consisting of oxygen concentration, the concentrations of the compounds, the concentration of their decomposition products, and / or combinations thereof.

15. The method of any of claims 1 to 14, wherein the parameters in the circuit using measurement units are continuously measured.

16. The method of any of claims 8 to 15, wherein the parameters are measured in the circulating water.

17. The method of any of claims 12 to 16, wherein the parameters are measured in the feed water portion and / or the main condensate portion.

18. The method of any of claims 1 to 17, wherein the compounds act an oxygen scavenger when exposed to gamma radiation.

19. System for dynamically controlling corrosion in a steam-water circuit of a nuclear power plant using ethanolamine and optionally ammonia, the system comprising: - injection units, located at a dosing point and configured for injecting the compounds ethanolamine and optionally ammonia in the fluid circulating in the circuit; and - measurement units, configured for measuring a value of the parameters pH and at least one of the parameters selected from redox potential and corrosion potential in the circuit; the system further comprising a control unit, the control unit comprising: - a first acquisition module, connected to the measurement unit and configured for acquiring the measured values of the parameters and configured for acquiring at least one set-point value for said parameters; - a command module, connected to the injection units and configured for commanding the injection of the compounds ethanolamine and optionally ammonia by the injection unit as a function of the acquired at least one set-point value and measured values of the parameters, characterized in that ethanolamine is used as reducing agent.

20. The system of claim 19, wherein the command module connected to the injection units is further configured for commanding the injection of the compounds ethanolamine and ammonia by the injection unit under further consideration of weighting factors for ethanolamine and ammonia determined based on at least two criteria selected from toxicity, water compatibility, decomposition products, IEX fouling, alkalisation efficiency and reductive efficiency.

21. The system of claim 19 or 20, wherein the acquisition module and the command module form a control unit.

22. The system of any of claims 19 to 21, wherein the steam water circuit comprises a feed water container and the dosing point is located downstream from the feed water container.

23. The system of any of claims 19 to 22, wherein the steam-water circuit comprises a main condensate pump and the dosing point is located downstream from the main condensate pump.

24. The system of any of claims 19 to 23, wherein further compounds are injected and wherein said further compounds are selected from methanol, hydrazine, and / or combinations thereof.

25. The system of any of claims 19 to 24, wherein the concentration of the compounds in the circulating in the steam-water circuit is continuously measured.

26. The system of any of claims 19 to 25, wherein the steam-water circuit comprises a steam generator, wherein the steam generator has a circulation space, in which circulating water circulates to absorb heat from a primary coolant circuit.

27. The system of claim 26, wherein the concentration of the compounds is measured in the circulating water.

28. The method of any of claims 19 to 27, wherein the concentration of ethanolamine in the circulating water is from 1 x 10-8mol / kg to 1 x 10-3mol / kg and the concentration of ammonia in the circulating water is 3.5 x 10-3mol / kg or less, preferably, the concentration of ammonia in the circulating water is 3.5 x 10-6to 3.5 x 10-3mol / kg.

29. The method of any of claims 24 to 28, wherein the concentration of methanol in the circulating water is from 1 x 10-7mol / kg to 1 x 10-3mol / kg and / or the concentration of hydrazine in the circulating water is 6.25 x 10-7mol / kg or less, more preferably, the concentration of hydrazine in the circulating water is from 3 x 10-9mol / kg to 6.25 x 10- 7 mol / kg.

30. The method of any of claims 19 to 29, wherein the steam-water circuit comprises a feed water portion and a main condensate portion.

31. The method of claim 30, wherein the concentrations of the compounds are measured in the feed water portion and / or the main condensate portion.

32. The method of any of claims 19 to 31, wherein further parameters measured and acquired and for which at least one set-point value is acquired, are selected from the group consisting of the oxygen concentration, the concentrations of the compounds, the concentration of their decomposition products, and / or combinations thereof.

33. The method of any of claims 19 to 32, wherein the parameters in the circuit using measurement units are continuously measured.

34. The method of any of claims 26 to 34, wherein the parameters are measured in the circulating water.

35. The method of any of claims 30 to 34, wherein the parameters are measured in the feed water portion and / or the main condensate portion.

36. The method of any of claims 19 to 35, wherein the compounds act an oxygen scavenger when exposed to gamma radiation. .

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