Lithium meter: method and mobile device for continuous lithium measurement

Abstract

A method for monitoring and analyzing a primary fluid of a pressurized water reactor is proposed, the method comprising: obtaining (11) a set of measurements of the primary fluid, the set of measurements comprising at least one conductivity measurement by a conductivity probe connected to a nuclear sampling circuit of the reactor, and evaluating and / or monitoring (12) a parameter of the primary fluid on the basis of a result of an application of a predefined relationship integrating the set of measurements obtained. A device and a system suitable for implementing the method are also proposed. Abstract figure: Figure 1

Description

Title of the invention: Lithium meter: method and mobile device for continuous lithium measurement Technical field

[0001] The present disclosure relates to the fields of nuclear chemistry and instrumentation. More specifically, it relates to a method for monitoring and analyzing a primary fluid of a pressurized water reactor, as well as a device and a system suitable for implementing the method. Prior art

[0002] In the field of nuclear chemistry and instrumentation, monitoring and analysis of the primary fluid in a pressurized water reactor is essential to ensure safety and compliance with the operating conditions of the plant. Historically, these processes involve periodic measurements of various physicochemical parameters, including conductivity, temperature and the concentration of certain constituents such as boron and lithium.

[0003] Traditional methods, although reliable, are often time-consuming and involve manual interventions, thus limiting the ability to respond quickly to changes in reactor conditions.

[0004] Furthermore, on N4 stage reactors, there are measuring systems such as boremeters or lithium meters, permanently connected to the primary circuit. These systems process a raw measurement signal according to an internal calculation algorithm, which is difficult to modify. Although effective, these systems have limited flexibility and a restricted scope of application. They do not allow rapid adaptation to updates of operational procedures.

[0005] Therefore, there is a need for more adaptive and responsive monitoring and analysis of primary fluid conditions while reducing manual interventions in the measurement process. Summary

[0006] The present disclosure improves the situation.

[0007] A method for monitoring and analyzing a primary fluid of a pressurized water reactor is provided, the method comprising: obtaining a set of measurements of the primary fluid, the set of measurements comprising at least one conductivity measurement by a conductivity probe connected to a nuclear sampling circuit of the reactor, and an evaluation and / or monitoring of a physicochemical parameter of the primary fluid based on a result of an application of a predefined relationship integrating the whole of measurements obtained.

[0008] Also provided is a mobile device comprising: a conductivity probe configured to measure a conductivity of a primary fluid of a nuclear reactor, said probe being adaptable for connection to a nuclear sampling circuit of the reactor, and a connection interface capable of conveying a signal representative of the conductivity measured by the probe.

[0009] There is also provided a system for monitoring and analyzing a primary fluid of a pressurized water reactor, the system comprising the aforementioned mobile device and a data processing circuit comprising: an interface for receiving the signal from the mobile device, and a processing module configured to evaluate and / or monitor a physicochemical parameter of the primary fluid based on a result of an application of a predefined relationship integrating at least the conductivity measured by the probe.

[0010] The proposed technique allows for efficient assessment of a physicochemical parameter of the primary fluid based on at least one conductivity measurement. Furthermore, the use of multiple conductivity measurements enriches the analysis by providing a more dynamic and detailed overview of changes in the primary fluid. Monitoring a physicochemical parameter through a plurality of successive conductivity measurements allows for continuous monitoring and real-time adjustment of reactor conditions, thereby improving safety and operational efficiency.

[0011] The mobility of the conductivity probe offers significant flexibility and adaptability compared to fixed systems, allowing a more targeted and personalized analysis of the physicochemical parameters according to the current state of the reactor. The mobility of the conductivity probe also gives the proposed technique a capacity to assist in the implementation of possible maneuvers such as an injection of a conditioning product into the primary fluid or a deconcentration of the primary circuit.

[0012] The integration of the measurements into a data processing circuit, possibly separate from the reactor control system, facilitates the in-depth interpretation of the measurements and offers increased responsiveness in response to updates to the operational procedures.

[0013] The features set out in the following paragraphs may, optionally, be implemented, independently of one another or in combination with one another:

[0014] The parameter of the primary fluid may be a concentration of the primary fluid in a conditioning product containing one of lithium hydroxide, hydrogen peroxide or hydrazine hydrate and / or a concentration of the primary fluid in an impurity. Evaluating this parameter or monitoring its evolution helps to strengthen the precision of chemical control of the primary fluid, thus improving the safety and performance of the reactor.

[0015] The set of measurements may comprise, in addition to the conductivity measurement: a measurement temperature associated with the conductivity measurement, and / or a measurement of a quantity representative of a concentration of at least one constituent of the primary fluid. The measurement of the conductivity is influenced by several factors, in particular the temperature and the concentrations of the different chemical species in solution in the primary fluid. For certain applications, an approximation of the actual values ​​of the measurement temperature and / or the concentrations of the chemical species present using standard values ​​may provide sufficient precision to evaluate or monitor a specific physicochemical parameter. For example, in the routine monitoring of a known and stable concentration of a packaging product, this simplified approach may be adequate.However, for more complex or critical applications such as lithium concentration monitoring, it is preferable to have accurate measurements not only of conductivity, but also of the measurement temperature and optionally of the boron concentration. This approach allows for finer precision in determining the physicochemical parameter of the primary fluid, thus ensuring a more accurate and reliable assessment or monitoring. This adaptability in the measurement approach enhances the versatility of the process and increases its applicability to a wide range of operational conditions in the reactor.

[0016] The method may comprise a comparison of the conductivity measurement or the result of the application of the predefined relationship with at least one predefined threshold.

[0017] The method may include issuing an alert based on a result of the comparison. Such an approach facilitates a rapid response in the event of an anomaly.

[0018] The method may include an update of the predefined relationship. The ability of the proposed technique to enable such an update makes it scalable and facilitates maintaining operational procedures in compliance with the latest practices and scientific advances.

[0019] Measurement of the conductivity of the primary fluid and evaluation and / or monitoring of the parameter can be performed in real time. This helps to improve operational efficiency and speed up decision-making.

[0020] The method may include automatic calibration of the conductivity probe prior to the conductivity measurement. This calibration ensures the reliability and accuracy of the conductivity measurement.

[0021] The system may include a fastening mechanism allowing removable connection of the probe to the nuclear sampling circuit. This fastening mechanism, for example based on magnets or screw elements, offers great ease of use.

[0022] The system may include a containment enclosure configured to house the probe while providing isolation from an external environment when the probe is connected to the nuclear sampling circuit. The enclosure protects the probe and ensures the safety of personnel and the environment.

[0023] The system may comprise a transmitter connected to the connection interface of the mobile device and a receiver connected to the reception interface of the data processing circuit, the transmitter and the receiver being configured to communicate by radio waves. This mode of communication allows fast and reliable data transmission.

[0024] The system may include a user interface allowing real-time visualization of the conductivity measurement, a value of the parameter and / or an indicator of a change in the parameter. A user interface facilitates accessibility of the data for operators.

[0025] According to another aspect, there is provided a computer program comprising instructions for implementing all or part of a method as defined herein when this program is executed by a processor. According to another aspect, there is provided a non-transitory, computer-readable recording medium on which such a program is recorded. Brief description of the drawings

[0026] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0027] [Fig.l] illustrates a system for monitoring and analyzing the primary fluid of a pressurized water reactor, according to an exemplary embodiment. Fig. 2

[0028] [Fig.2] illustrates a method for monitoring and analyzing the primary fluid of a pressurized water reactor, according to an exemplary embodiment. Fig. 3

[0029] [Fig.3] illustrates a graphical interface of a data processing system, according to an exemplary embodiment. Fig. 4

[0030] [Fig.4] illustrates a data processing system, according to an exemplary embodiment. Description of the embodiments

[0031] In the following description, identical reference numerals designate identical elements or elements having similar functions.

[0032] The present disclosure relates to a technique for determining a concentration of a conditioning product in a primary fluid of a pressurized water reactor.

[0033] The primary fluid in this context comprises water containing boron, specifically in the form of boric acid, used to regulate the neutron flux during the nuclear fission reaction. The concentration of this boric acid fluctuates between about 3000 mg / kg and 0 mg / kg, depending on the stage of the production cycle.

[0034] In order to limit the corrosion phenomenon due to the acidic nature of boric acid and consequently to reduce the quantity of radioactive products in the primary circuit, it is necessary to maintain a constant pH known as "lower corrosion". To do this, lithium hydroxide is injected into the primary circuit in an amount proportional to the boron concentration. It is necessary to be able to regularly measure the concentration of these different components to maintain the target pH and limit the effects of corrosion. In addition to lithium hydroxide, other conditioning products are used to meet other needs. For example, during the shutdown phase of a unit, oxygenation of the primary circuit is carried out using hydrogen peroxide (H2O2), while during the restart phase of a unit, an injection of hydrazine hydrate (H2N-NH2H2O) is carried out.

[0035] The presence of lithium in the primary circuit aims to permanently maintain an optimal pH defined at 300°C, the temperature of the primary fluid when the unit is in production, i.e. when the neutron power is greater than 5%. However, directly measuring the pH at such temperatures is not feasible, making it necessary to monitor the lithium concentration to ensure the correct chemical balance.

[0036] The optimal lithium concentration is closely correlated with the boron concentration in the primary circuit, according to the principle of "boron-lithium coordination" which is a relationship established in the chemical specifications for operating power plants. Historically, this coordination has evolved over time, from an initial formulation in 1987 to more recent and refined versions, reflecting changes in operational needs and reactor operating conditions.

[0037] According to boron-lithium coordination, the lithium concentration must remain within an operating tolerance zone (or zone 1) around a reference value. As long as the lithium concentration remains within this operating tolerance zone, no action to adjust the lithium concentration is implemented. Depending on the conditions of the unit, for example in a scenario of power variations, it may happen that the lithium concentration leaves this operational zone, thus requiring an intervention to restore the balance and return to zone 1 within a specified time, by means of a lithium injection when the lithium concentration is too low or deconcentration when the lithium concentration is too high.

[0038] The 1987 boron-lithium coordination, called "decreasing lithium" was defined according to the following three ranges where "CB" designates the boron concentration and "[Liref]" designates the associated reference value CB < 270 mg / kg, [Liref] = 0.7 270 < CB < 1100 mg / kg, [Liref] = 0.0018 x CB + 0.22 CB > 1100 mg / kg, [Liref] = 2.2.

[0039] In accordance with the boron-lithium coordination of 1987, the lithium concentration in the primary circuit was limited to 2.2 mg / kg in view of the risks of corrosion of the fuel cladding made of Zircaloy 4 alloy. This limitation results in obtaining a pH at the start of the cycle lower than international standards (pH < 6.9 at 300°C) for boron contents above approximately 1200 mg / kg. Operation under such conditions can lead to an increase in the release of corrosion products in the primary circuit, with the consequence of significant contamination within this circuit (dosimetric impact) as well as an increase in the risk of deposition of corrosion products on the fuel, which can induce neutron flux deformations and / or localized corrosion phenomena of the cladding.According to national and international feedback, the consequences of this operation at too low a pH have led certain power plants to make intermediate shutdowns and / or to reduce the average core temperature, impacting the productivity of these units.

[0040] To overcome these problems, a modification of the boron-lithium coordination was carried out; it consists of increasing the lithium concentration at the start of the cycle up to a maximum admissible value of 3.5 ppm over a limited period. This modification of the primary chemistry makes it possible to achieve, for any fuel management, a pH at 300°C at the start of the cycle greater than 6.9, the minimum value retained by international standards.

[0041] Thus, the boron-lithium coordination currently in force is defined according to four ranges, namely: CB < 540 mg / kg, [Liref] = 0.00278 x CB + 0.5 540 < CB < 900 mg / kg, [Liref] = 2.0 900 < CB < 1500 mg / kg, [Liref] = 0.00217 x CB + 0.047 CB > 1500 mg / kg, [Liref] = 3.3.

[0042] A general principle for determining the lithium concentration in the primary cooling circuit of a nuclear reactor is set out in patent FR8707690. This principle specifically meets the need defined according to the boron-lithium coordination "decreasing lithium" and is based on a law of variation of the conductivity as a function of temperature, boron concentration and lithium concentration.

[0043] A known method, currently implemented, for analyzing the lithium concentration in the primary fluid involves daily sampling of the primary fluid. This method requires careful handling and specific laboratory equipment. The implementation of the entire process, including the collection of a sample, its transfer to the analysis laboratory, the analysis of the sample and the validation of the result requires approximately three hours, excluding contingencies. Such an analysis delay impacts the management of the reagents injected into the primary circuit. There may be periods when the necessary chemical conditioning cannot be adjusted in a timely manner, leaving the primary circuit temporarily in a less optimal state, and potentially increasing the risks of corrosion.Therefore, a more efficient and rapid method for measuring conditioning product concentrations is required, to allow real-time adjustment of the chemical conditioning of the primary fluid, and in the specific case of lithium, to optimally maintain the least corrosion pH.

[0044] Alternatively, another known method, currently implemented in N4 nuclear power plants, to monitor the lithium concentration involves the use of lithium meters. These devices, installed at the design of the units, are placed on specific lines in parallel with a boron meter. Their fixed location limits the flexibility of their use, as it does not allow the location of the control to be adjusted or specified. In N4 type units, the lithium meters are configured to measure the conductivity of the primary fluid and to determine the lithium concentration by applying a variation law as set out in patent FR8707690. This variation law is integrated into the unit's control command, which does not allow easy adaptation to changes in chemical specifications.Indeed, any necessary changes in the configuration of the lithium meters to align with the new specifications of boron-lithium coordination would require specialized intervention from an external company. Such an adjustment is considered a sensitive activity directly linked to the safety of the unit concerned, which underlines the need for a more adaptable and responsive solution.

[0045] The proposed technique makes it possible, like known methods, to determine a lithium concentration in the primary circuit of a pressurized water reactor based on a conductivity measurement. However, it offers several distinct advantages which make it superior to existing solutions.

[0046] Unlike traditional methods requiring one-off sampling, the proposed technique allows for continuous monitoring of conductivity. It also considerably reduces the analysis time to only 30 minutes in com comparison of the three hours or more required by conventional methods. This rapid analysis facilitates the maintenance of the pH of the primary fluid, particularly in situations of power variations such as shutdown and restart phases. The proposed technique thus contributes to better management of corrosion risks and other associated chemical problems, thereby increasing the overall safety of reactor operations.

[0047] Continuous monitoring of the conductivity of the primary fluid also represents an optimization of chemical activities in that it offers a significant reduction in the operational load compared to traditional methods requiring one-off sampling. Operational resources can thus be redeployed to other activities. Furthermore, the reduction in the number of manual samples makes it possible to reduce annual collective dosimetry by approximately 17%.

[0048] To ensure continuous monitoring of the conductivity of the primary fluid, the proposed technique provides for the use of a conductivity probe that is mobile and adaptable to a variety of locations. The probe is mobile in that it is easily disassembled and transportable from one location point to another. In other words, the probe is designed to be able to be selectively connected to one of several possible locations provided at a sampling circuit of the nuclear reactor. Optionally, the probe can be connected to an location point that is not part of the sampling circuit, for example an effluent treatment line, in order to study the effectiveness of a chemical treatment of the effluents.

[0049] The conductivity probe can also be made available to several nuclear reactors. To enable this pooling, it is appropriate to provide connection points at the level of the respective sampling circuits of several nuclear reactors on the same site. Thus, a single monitoring and analysis system may be sufficient to monitor the execution of the same type of maneuver, such as the injection of hydrogen peroxide during a unit shutdown phase, on the scale of an entire site, provided that these maneuvers are programmed successively and not simultaneously for several reactors.

[0050] In an exemplary implementation, the conductivity probe is housed in a containment enclosure, such as a glove box, ensuring isolation of the primary fluid from an external environment when the probe is connected to the nuclear sampling circuit. The conductivity probe may or may not be integral with the glove box. The installation of the conductivity probe in a glove box makes it possible to avoid chemical and radiochemical risks.

[0051] The information collected by the conductivity probe is processed by a data processing system to evaluate and / or monitor a parameter of the primary fluid by application of a pre-established relationship. This system is distinct from the reactor control command.

[0052] To calculate the concentration of a conditioning product, for example lithium, the data processing system can be configured to use a pre-established formula or relationship taking into account several parameters, including the conductivity at a measurement temperature (typically 25°C), the measurement temperature, and the concentration of boron or other known chemical species affecting conductivity.

[0053] In addition to monitoring the concentration of a packaging product, several other applications of the proposed technique are conceivable.

[0054] For example, in the context of monitoring the saturation of a demineralizer during a lithium injection, it may be planned to monitor the evolution of the conductivity during the injection to detect a characteristic variation associated with an increase in the lithium concentration in the fluid after saturation of the demineralizer.

[0055] Another example is the monitoring of the oxygenation of the primary circuit during an injection of hydrogen peroxide during the shutdown phase of a unit. Here, the predefined relationship can be based on a difference in conductivity before and after the injection, the result of which can be compared to a reference in order to evaluate the quantity of dissolved oxygen and, consequently, the efficiency of the oxygenation. During the restart phase of a unit, the proposed technique can also be used for monitoring hydrazine hydrate (H2N-NH2H2O). In general, monitoring the conductivity during the injection of a conditioning product allows precise control of the necessary quantities and avoids overconsumption of the conditioning product.

[0056] In the context of the purification of the primary circuit, the proposed technique can be a tool for detecting the presence or increase of impurities based on conductivity monitoring. The predefined relationship can then consist of conductivity thresholds, these thresholds being able to be adjusted according to optional measurements such as the conductivity measurement temperature or the boron and / or lithium concentration, to identify the presence or increase of impurities and the need for intervention for purification.

[0057] It is possible to define a plurality of pre-established formulas or relationships, each meeting a different need. For example, several pre-established formulas can be provided, each making it possible to determine the concentration of a distinct chemical species. This approach makes it possible to monitor, through appropriate use of the conductivity measurements obtained, the concentrations not only of lithium, but also of other conditioning products and impurities. Thus, thanks to the mobility of the conductivity probe and thanks to the possibility of applying different formulas to calculate the concentrations of several conditioning products possible, the proposed technique not only allows the lithium concentration of the primary fluid to be continuously determined but also meets other needs. The proposed technique makes it possible in particular to secure the commissioning of a demineralizer ensuring the purification of the primary circuit by measuring the conductivity upstream and downstream of the demineralizer, or to monitor the conductivity of the conditioning products injected during the shutdown and restart phases of a unit.

[0058] The pre-established formulas can also be made modifiable, for example it may be useful to modify the formula for calculating the lithium concentration to adapt to present and future developments in boron-lithium coordination. In the context of using the same conductivity probe at several reactors of different types within the same site, different sets of pre-established formulas can be provided, each set of pre-established formulas being designed to meet the specific needs of a corresponding type of reactor.

[0059] In an exemplary embodiment, the proposed technique further provides for the use of a transmitter connected to the conductivity probe to transmit the conductivity measurements to the data processing system.

[0060] The general principle of a method for continuously measuring lithium concentration is now described in an exemplary embodiment.

[0061] The sampling circuit comprises several sampling lines. The boron concentration of the primary fluid is continuously measured, at one of the sampling lines, by means of a boron meter. The ammonia content of the primary fluid is determined weekly by analyzing samples using laboratory equipment. The conductivity measurement temperature is continuously measured using a temperature sensor. Finally, the conductivity of the primary fluid is measured by the conductivity probe. The sampling and the chemical measurements such as the boron measurement and the conductivity measurement are carried out within the temperature range tolerated for the operation of the boron meter, namely between 15°C and 35°C. To do this, the temperature of the sampling lines is maintained within this temperature range by means of refrigerant.

[0062] These measurements make it possible to calculate the lithium ion content of the primary fluid, for example according to a linear relationship of the form [Li+] = ax X + [3 where: a is a dimensionless proportionality coefficient, X denotes the circuit conductivity in pS / cm, and [3 is a corrective term taking into account possible impurities, such as ammonia, which may be present in the primary fluid.

[0063] For a given composition of the primary fluid, and in particular for a boron- lithium defined according to the current boron-lithium coordination, the conductivity varies according to the measurement temperature, for example according to a linear relation of the form Xt = axt + b, where the term "a" is the slope coefficient of the linear function X = f(t) for the given composition.

[0064] At 25°C we then have X (25°C) = 25a + betsib = Xt-axt, then X (25°C) =

[0065] By carrying out theoretical calculations of conductivity between 15°C and 35°C as a function of specific boron-lithium couples according to the current boron-lithium coordination, the following data are then obtained: [Liref] (mg / kg) 0.51 0.79 1.08 1.36 1.65 1.94 2.00 CB (mg / kg) 5 100 200 300 400 500 600 T (°C) Theoretical Conductivity Cth (pS / cm) 15 4.84 7.16 9.73 12.16 14.62 17.01 17.36 20 5.54 8.08 10.97 13.72 16.5 19.2 19.6 25 6.23 8.92 12.11 15.15 18.2 21.25 21.71 30 7.08 9.91 13.47 16.85 20.29 23.66 24.19 35 8.0 10.84 14.72 18.42 22.19 25.88 26.48 a 0.1552 0.1838 0.2496 0.313 0.379 0.444 0.456 b 2.448 4.387 5.96 7.435 8.901 10.314 10.474 [Liref] (mg / kg) 2.00 2.00 2.02 2.24 2.67 3.11 3.30 CB (mg / kg) 700 800 900 1000 1200 1400 1600 T (°C) Theoretical conductivity Cth (pS / cm) 15 17.19 17.02 17.04 18.73 21.98 25.27 26.57 20 19.44 19.27 19.3 21.2 24.9 28.6 30.1 25 21.52 21.3 21.37 23.49 27.56 31.68 33.28 30 23.99 23.79 23.84 26.22 30.77 35.38 37.16 35 26.27 26.07 26.14 28.75 33.8 38.8 40.75 a 0.454 0.452 0.455 0.501 0.588 0.677 0.709 b 10.327 10.186 10.161 11.155 21.98 25.27 26.57 [Liref] (mg / kg) 3.30 3.30 3.30 3.30 3.30 3.30 3.30 CB (mg / kg) 1800 2000 2200 2400 2600 2800 3000 T (°C) Theoretical conductivity C* (pS / cm) 15 26.4 26.28 26.22 26.19 26.2 26.25 26.32 20 29.9 29.7 29.6 29.6 29.6 29.6 29.7 25 33.04 32.87 32.76 32.7 32.69 32.72 32.8 30 36.88 36.68 36.55 36.47 36.45 36.48 36.55 35 40.44 40.2 40.04 39.95 39.91 39.92 39.98 a 0.702 0.696 0.691 0.688 0.685 0.684 0.683 b 15.774 15.75 15.767 15.787 15.835 15.912 15.999

[0066] The function a = f([Liref]) can be established by linear regression from the previous data, with the optimization result a = 0.196 x [Liref] + 0.0519. We then obtain X (25°C) = X t + (0.196 x [Liref] + 0.0519) x (25 -1), from which [Li+] = ax [Xt + (0.196 x [Liref] + 0.0519) x (25 -1)] + [3. Considering a reference measurement temperature equal to 25°C and a total absence of impurities likely to mark the conductivity (i.e. [3 = 0) we obtain [Li+] = ax X t. For each boron-lithium couple previously cited, it is possible to deduce a corresponding value of the coefficient a from the theoretical conductivities at 25°C. [Liref] (mg / kg) 0.51 0.79 1.08 1.36 1.65 1.94 2.00 CB (mg / kg) 5 100 200 300 400 500 600 Cth (pS / cm), T = 25°C 6.23 8.92 12.11 15.15 18.2 21.25 21.71 a 0.08 0.09 0.09 0.09 0.09 0.09 0.09 [Liref] (mg / kg) 2.00 2.00 2.02 2.24 2.67 3.11 3.30 CB (mg / kg) 700 800 900 1000 1200 1400 1600 C* (pS / cm), T = 25°C 21.52 21.3 21.37 23.49 27.56 31.68 33.28 a 0.09 0.09 0.09 0.10 0.10 0.10 0.10 [Liref] (mg / kg) 3.30 3.30 3.30 3.30 3.30 3.30 3.30 CB (mg / kg) 1800 2000 2200 2400 2600 2800 3000 C* (pS / cm), T = 25°C 33.04 32.87 32.76 32.7 32.69 32.72 32.8 a 0.10 0.10 0.10 0.10 0.10 0.10 0.10

[0067] Considering by approximation the coefficient a as being equal to a value of 0.10, that is to say as being equal to the calculated average value of a for all the boron-lithium couples previously cited, we obtain [Li+] = 0.10 x [Xt + (0.196 x [Liref] + 0.0519) x (25 -1)] + [3.

[0068] Based on the current boron-lithium coordination, the following four boron concentration ranges can be defined: CB < 540 mg / kg, [Liref] = 0.00278 x CB + 0.5, 540 < CB < 900 mg / kg, [Liref] = 2.0, 900 < CB < 1500 mg / kg, [Liref] = 0.00217 x CB + 0.047, and CB > 1500 mg / kg, [Liref] = 3.3.

[0069] By applying the relationship between [Liref] and [Li+] obtained by linear regression of the theoretical conductivity calculations previously mentioned, we obtain the following set of equations allowing us to calculate the lithium ion concentration [Li+] of the primary fluid from the conductivity measurements, the measurement temperature and the boron concentration of the primary fluid: for CB < 540 mg / kg, [Li+] = 0.1 x [X(t) + (0.0005449 for 900 < CB < 1500 mg / kg, [Li+] = 0.1 x [X(t) + (0.0004253 x Cb + 0.0611) x (25-t)] + [3, and for CB > 1500 mg / kg, [Li+] = 0.1 x [X(t) + 0.6987 x (25-t)] + [3.

[0070] Reference is made to [Fig. 1], illustrating an exemplary system for monitoring and analyzing the primary fluid of a pressurized water reactor, and to [Fig.2], which represents an exemplary method of monitoring and analyzing using the system of [Fig.l].

[0071] The monitoring and analysis system comprises the following elements: a mobile device comprising at least one conductivity measuring probe 3 installed and configured so as to measure the conductivity of the primary fluid, a containment enclosure 2, such as a REN glove box in which cable trays are arranged, the containment enclosure being designed to physically isolate the primary fluid and the mobile device from the external environment, and a measuring circuit ensuring the supply of primary fluid to the mobile device from the sampling circuit of the reactor, the measuring circuit comprising a connection point 5 to the sampling circuit, a sampling valve 1 controlling the circulation of the primary fluid in the measuring circuit, and reinforced supply hoses 4, and a transmitter 6, connected to the mobile device by the cable paths and configured to transmit the data collected by the conductivity measuring probe to a data processing system.

[0072] The monitoring and analysis system may also comprise a variety of sensors provided and configured to measure quantities of interest, for example a sensor 7 for measuring the conductivity temperature or a device 8 for measuring the boron concentration of the primary circuit. The sensors may be connected directly or indirectly to the data processing system. For example, the sensor 7 may be integrated into the mobile device and may be connected to the transmitter 6 which may be configured to transmit not only the conductivity measurement but also the associated measurement temperature to the data processing system.

[0073] The monitoring and analysis system may also comprise an alert module, for example a visual or audible alert, configured to signal an anomaly, for example an anomaly relating to a state of the primary fluid, such as a measured conductivity value which deviates from an expected value, or an anomaly relating to an operation of the monitoring and analysis system, for example an absence of reception, by the treatment system, of an expected measurement at a given time.

[0074] The data processing system 30, shown in [Fig. 4], comprises several functional modules. These functional modules are implemented by computer according to methods known per se. Typically, the data processing system data comprises at least one processor connected to at least one memory or data storage medium and to at least one communication interface. The memory stores at least one computer program comprising one or more instructions which, when executed by the processor, cause the processor to implement all or part of the aforementioned monitoring and analysis method.

[0075] A receiving or input module 31 receives the data to be processed, in particular signals from the transmitter 6 received via the communication interface and containing conductivity measurements from the conductivity probe 3. These signals can pass either individually for each measurement, or in groups in the form of series of measurements. Once received, these signals are processed by a data extraction module configured to extract the precise conductivity measurements therefrom. The receiving module can be configured to receive the data from a single source or from several sources. For example, a measurement system 8 comprising a sensor, for example a boremeter, and a transmitter can represent an additional source of data.

[0076] A measurement recording module 32 may be provided to store the extracted measurements by recording them in a structured manner, for example in a spreadsheet. Each conductivity measurement may be placed in a specific box in the spreadsheet, with adjacent boxes possibly provided for a timestamp or a measurement number, thus facilitating chronological tracking and organization of the data.

[0077] A calculation module 33 uses the extracted measurements to calculate one or more parameters of the primary fluid, for example the lithium concentration, based on one or more predefined relationships, and an output module 34 is configured to provide the parameter(s) calculated by the calculation module.

[0078] These relationships are recorded in a structured manner, for example in specific boxes of the spreadsheet, by a module for recording predefined relationships. A selection module may be provided to choose the appropriate predefined relationship for each situation, given that each predefined relationship has a field of application, for example it may be specific to a particular reactor or having particular specifications, to a particular operational condition of the reactor, to a particular type of parameter to be determined, etc.

[0079] A selection module 35 may be provided to enable one or more predefined relationships to be selected to be implemented by the calculation module from a library of predefined relationships. The selection module may for example be implemented using a drop-down menu on a graphical interface.

[0080] An update module 36 may be provided to enable the predefined relationships to be updated, for example by editing, via a human-machine interface ap appropriate, the contents of the spreadsheet boxes in which these relationships are saved. Alternatively, predefined relationships can be saved in locked, therefore non-editable, spreadsheet boxes.

[0081] The monitoring and analysis system may comprise a display configured to display the measurements currently obtained by the monitoring and analysis system, i.e. at least one current conductivity measurement but also, optionally, a current temperature measurement for example. The display may for example be integrated into the transmitter 6, as in the example of [Fig. 1].

[0082] A graphical interface 36 may also be provided at the data processing system, configured to display the measurements currently obtained by the data processing system. The graphical interface may further be configured to display one or more parameters calculated by the calculation module and provided by the output module of the data processing system.

[0083] [Fig. 3] represents an example of a graphical interface 26 in the form of a spreadsheet comprising a box 20 indicating a boron concentration of the primary fluid, provided by a boron meter, a box 21 indicating a conductivity of the primary fluid, provided by the conductivity probe, a box 22 indicating a measured temperature of the primary fluid at the conductivity probe at the time of the conductivity measurement, a box 23 indicating an estimated value of a coefficient involved in a pre-established relationship between the values ​​present in boxes 20, 21 and 22 and the lithium concentration of the primary fluid, an interactive box 24 allowing access to the mathematical formula of the pre-established relationship and a box 25 indicating the lithium concentration of the primary fluid as calculated by applying the pre-established relationship.

[0084] The method shown in [Fig.2] comprises a phase 10 of installing the monitoring and analysis system, a phase 11 of collecting conductivity values ​​measured by the probe and transmitted by the transmitter and finally a phase 13 of uninstalling the monitoring and analysis system.

[0085] The installation phase of the monitoring and analysis system comprises: mounting the conductivity measuring probe against the internal wall of the containment enclosure using a removable attachment, for example using magnets, a connection of the probe to the sampling circuit using the reinforced hoses and a circulation of the primary fluid to the probe, activated by the opening of the sampling valve, and installation of the transmitter and powering up the monitoring and analysis system. After the installation phase, the monitoring and analysis system is immediately operational.

[0086] Conversely, the disassembly phase of the monitoring and analysis system includes closing the valves to isolate the primary fluid supply and disconnecting the hoses, disconnecting and disassembling the transmitter, and removing the probe, the reinforced hoses and the removable attachment from the containment enclosure. This disassembly phase allows complete disassembly of the monitoring and analysis system in approximately 20 minutes for potential reuse at another connection point.

[0087] As part of the collection phase, the probe can be configured to acquire conductivity measurements. The acquisition of the measurements can for example be continuous, that is to say periodic and according to a predetermined acquisition step. The acquisition step is optionally adjustable according to the needs. It can also be provided to trigger a conductivity measurement upon request received using for example a human-machine interface or a specific control signal. The probe can also be configured to self-calibrate, for example automatically before carrying out a measurement and / or periodically and / or upon request. The measured conductivity values ​​are automatically transmitted to the data processing system which is configured to carry out an evaluation and / or monitoring 12 of a parameter of the primary fluid based on at least one predefined relationship using at least one measured conductivity value.

[0088] The present disclosure is not limited to the examples described above, only by way of example, but it encompasses all the variants that the person skilled in the art may envisage within the framework of the protection sought.

Claims

Claims

1. Method for monitoring and analyzing a primary fluid of a pressurized water reactor, the method comprising: obtaining (11) a set of measurements of the primary fluid, the set of measurements comprising at least one conductivity measurement by a conductivity probe connected to a nuclear sampling circuit of the reactor, and evaluating and / or monitoring (12) a parameter of the primary fluid on the basis of a result of an application of a predefined relationship integrating the set of measurements obtained.

2. A method according to the preceding claim, wherein the parameter of the primary fluid is a concentration of the primary fluid in a conditioning product containing one of lithium hydroxide, hydrogen peroxide or hydrazine hydrate and / or a concentration of the primary fluid in an impurity.

3. Method according to one of the preceding claims, in which the set of measurements further comprises: a measurement temperature associated with the measurement of the conductivity, and / or a measurement of a quantity representative of a concentration of at least one constituent of the primary fluid.

4. Method according to one of the preceding claims, comprising a comparison of the conductivity measurement or the result of the application of the predefined relationship with at least one predefined threshold.

5. Method according to the preceding claim, comprising issuing an alert based on a result of the comparison.

6. Method according to one of the preceding claims, comprising an update of the predefined relationship.

7. Method according to one of the preceding claims, in which the measurement of the conductivity of the primary fluid and the evaluation and / or monitoring of the parameter are carried out in real time.

8. Method according to one of the preceding claims, comprising an automatic calibration of the conductivity probe before the conductivity measurement.

9. A mobile device comprising: a conductivity probe configured to measure a conductivity of a primary fluid of a nuclear reactor, said probe being adaptable for connection to a nuclear sampling circuit of the reactor, and a connection interface capable of conveying a signal representative of the conductivity measured by the probe.

10. System for monitoring and analyzing a primary fluid of a pressurized water reactor, the system comprising a mobile device according to the preceding claim and a data processing circuit comprising: an interface for receiving the signal from the mobile device, and a processing module configured to evaluate and / or monitor a parameter of the primary fluid on the basis of a result of an application of a predefined relationship integrating at least the conductivity measured by the probe.

11. System according to the preceding claim, comprising a fixing mechanism allowing removable connection of the probe to the nuclear sampling circuit.

12. The system of claim 10 or 11, further comprising a containment enclosure configured to house the probe while providing isolation from an external environment when the probe is connected to the nuclear sampling circuit.

13. System according to one of claims 10 to 12, comprising a transmitter connected to the connection interface of the mobile device and a receiver connected to the reception interface of the data processing circuit, the transmitter and the receiver being configured to communicate by radio waves.

14. System according to one of claims 10 to 13, comprising a user interface allowing real-time visualization of the conductivity measurement, of a value of the parameter and / or of an indicator of a change in the parameter.

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