JP2000321393A - Method and device for controlling concentration of nuclear reactor coolant water and concentration measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device measuring B and Li component concentrations quickly and accurately online in coolant in a primary cooling system of a pressurized water reactor and controlling the B and Li component concentrations in the primary cooling system to prescribed values based on the result, and to provide a measuring system for that purpose and a measuring cell used in the measuring system. SOLUTION: A measuring part for detection subject components is provided in a cooling system. Pulse laser light for generating plasma and pulse laser light for exciting the detection subject components are synchronously irradiated on coolant at the measuring part. Computers 34a, 34b calculate actual values of the concentration of the detection subject components based on plasma light generated by irradiating the pulse laser light for generating plasma, and light emitting intensity from the detection subject components generated by irradiating the pulse laser light for exciting. A control valve 37 on an adjusting line 10 for the detection subject components connected to the cooling system is controlled to open/close based on the actual values and prescribed values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for constantly measuring or monitoring the concentration of a component to be detected in a cooling system of a nuclear reactor, and more particularly to a method and an apparatus for measuring the concentration of B in cooling water in a primary cooling system of a pressurized water reactor. , Li component concentration is measured or calculated on-line and the B and Li component concentration is controlled to a specified value based on the measurement result. Further, the present invention relates to a measurement system of a component to be detected used in the method and the apparatus as described above, and further relates to a measurement cell used in the measurement system.

[0002]

2. Description of the Related Art As is well known, a pressurized water reactor (PW)
Since the reactivity control of R) is performed by changing not only the control rod position but also the boron concentration in the cooling water in the primary cooling system, water quality control of the cooling water is particularly important.
That is, the water quality management of the PWR primary cooling system is based on Inconel 6
It is to achieve the suppression of corrosion of primary constituent materials such as 00 and stainless steel and, consequently, the reduction of radioactivity.
Water quality standards are set and managed.

[0003] As described above, in PWR, boron is added to cooling water to control the degree of reactivity. However, since boron makes the water quality acidic, from the viewpoint of suppressing corrosion of the primary cooling system constituent materials, water is added to boron. The ph is adjusted by adding lithium. When lithium hydroxide is added to increase the pH, corrosion of Inconel 600 and stainless steel can be kept sufficiently low. However, the amount of lithium hydroxide cannot be increased to a certain extent from the viewpoint of corrosion of Zircaloy and hydrogen embrittlement. Accordingly, lithium concentration management corresponding to the boron concentration is performed, and one example is described in “Nuclear Handbook”, pages 186 to 193, “Reactor Water Chemistry” issued by Ohm Corporation.

[0004] In addition, as for the above-mentioned cooling water of the primary cooling system and the water on the secondary side, which becomes steam by exchanging heat in the steam generator, water quality management is important to maintain the soundness of the heat transfer tube of the steam generator. There are also secondary waters such as Ca, M
Water quality reference values such as g, Cr, Fe, Cu, Ni, Na, and Cl (chlorine) are defined.

[0005] On the other hand, the cooling water of a boiling water reactor (BWR) does not generally control the reactivity by boron injection, so that neutral pure water is used. Criteria are determined based on the degree of neutral pure water participation in the stainless steel, carbon steel, stellite, inconel, and other materials that constitute the system. Therefore, B
Water quality management of the WR plant is performed such that a reference value of impurities such as silica is set with respect to the reactor water and the supply water so that the reference value is not exceeded.

[0006] Regarding conventional water quality management methods, B, Li in cooling water of a pressurized water reactor, such as B, Li
Will be described with reference to FIG.
The concentration measurement of i is performed by manually pumping a cooling water sample from a sample line of a PWR plant to a sampling container in a sampling room (a waiting time of about 15 minutes is required for purging the sampling line), and radiochemical analysis. A method of manually carrying the sample into a room and obtaining analysis values by an analyzer such as a chemical analyzer or by manual analysis using a titration method has been adopted. For convenience, this is referred to as a known assay.

[0007] Although not shown, there is no application example used for measuring the B and Li concentrations in the reactor cooling water, but the following method has been proposed as a microanalysis method using a laser considered to be applicable. ing. (1) The LBS method (laser breakdown method) in which a laser beam is focused on a target solid / liquid / gas sample to convert the components into plasma, and the plasma emission is detected to measure the concentration of the trace component. (2) LIF for injecting a laser beam having a wavelength corresponding to the electron energy difference of the component to be detected, detecting the emission intensity of the excited measurement target component, and measuring the concentration of the trace component
Method (laser induced emission method).

[0008]

However, in the above-mentioned known analysis method, it is necessary to go through the following steps shown in FIG. 12 before obtaining an analysis result. (1) A fixed amount of a cooling water sample is collected in a sampling vessel in a sampling line (sampling room) of a reactor cooling system. (2) The collected sample container is transported to a radiochemical analysis room with measurement equipment. (3) Quantitative analysis of B and Li in the sample is performed in this analysis room. For Li, manual analysis is performed by the atomic absorption method in which elements are quantified by utilizing the light absorption phenomenon of atoms, which absorbs light of a specific wavelength, and for B, manual analysis is performed by NaOH titration.

As described above, according to the conventional known analysis method, it takes a considerable time (30 to 60 minutes) from collection of a sample from a measurement field to obtaining an analysis result. It is a technology far from realizing quick measurement of Li component concentration and realization of result processing, and in many cases, delays or the like are affected on progress of other processes related to the operation of a nuclear power plant. In addition, when the automation of the sample transport process is considered mainly for the above-described known analysis method, a transport device for sample samples, a transport pipe, an installation facility for the device, and the like are required, which has a disadvantage that the device is expensive.

[0010] Conventional measurement methods using a laser include an LBS method using only laser light for plasma generation,
There is an LIF method in which a laser beam having a wavelength corresponding to the electron energy difference of the component to be measured is incident. However, each of them has the following disadvantages. (1) Conventional L using pulsed laser light for plasma generation
In the BS method, a detection limit concentration up to the ppb level cannot be obtained. (2) Sufficient quantification accuracy cannot be ensured only by the conventional LIF method using the excitation pulse laser beam because of the large influence of the component binding state.

Accordingly, a first object of the present invention is to provide a method and an apparatus capable of quickly and accurately measuring the concentration of a component to be detected in water in a reactor cooling system online. Another object of the present invention is to measure the B and Li component concentrations in the cooling water in the primary cooling system of the pressurized water reactor quickly and accurately on-line, and based on the measurement results, the B and Li components of the primary cooling system. An object of the present invention is to provide a method and an apparatus for controlling the concentration of a component to a specified value. Further, the present invention provides
An object of the present invention is to provide a measurement system of a component to be detected, which can be used in the method and the apparatus as described above, and a measurement cell used in the measurement system.

[0012]

In order to achieve the first object described above, first, the concentration of a component to be detected in a reactor cooling system (hereinafter, simply referred to as "reactor cooling water concentration"). In the first aspect of the present invention, in a reactor having a cooling system, a method for controlling the concentration of the detection target component in the cooling water of the cooling system to a specified value is required. Setting a measurement field of the detection target component in the cooling system, irradiating the cooling water of the measurement field with a pulse laser beam for plasma generation, and generating plasma by irradiation with the pulse laser beam for plasma generation A concentration value of the detection target component is detected based on light, and a cooling water injection control valve of the cooling system is opened and closed by a concentration signal representing the concentration value.

According to another aspect of the invention, a laser-based LBS method and a LIF method are combined. This provides a method and an apparatus capable of quantifying the detection target component contained in the reactor cooling water with high accuracy up to the ppb order level. In order to achieve the above object, the present invention provides a method for controlling the concentration of a detection target component in cooling water of a cooling system to a specified value in a reactor having a cooling system, wherein the detection target component is contained in the cooling system. The measurement field is set, and the cooling water of the measurement field is irradiated with the pulsed laser light for plasma generation and the pulsed laser light for excitation of the component to be detected in synchronization with the irradiation of the pulsed laser light for plasma generation. A concentration value of the detection target component is detected based on an emission intensity emitted from the detection target component by irradiation of the excitation pulse laser beam, and a cooling water injection control valve of the cooling system is opened / closed by a concentration signal representing the concentration value. And a method for controlling the concentration of the component to be detected.

Further, in order to achieve the above object, the present invention relates to an apparatus for controlling a concentration of a component to be detected in cooling water of a cooling system to a specified value in a reactor having a cooling system, A measurement cell disposed in the measurement field of the detection target component set in the above, and the cooling water of the measurement cell are irradiated synchronously with the pulse laser light for plasma generation and the pulse laser light for excitation of the detection target component, respectively. A pulse laser for plasma generation and a pulse laser for excitation, and the actual concentration of the component to be detected based on the emission intensity emitted from the component to be detected by irradiation of the pulse laser beam for plasma generation and irradiation of the pulse laser beam for excitation Calculating means for continuously calculating a value; determining means for determining whether the actual value of the concentration of the detection target component is acceptable with respect to the specified value; A control valve for a detection target component adjustment line connected to the cooling system, and the control so that the actual value returns to the specified value when the actual value of the concentration of the detection target component is determined to be an abnormal value. A control device for controlling the opening and closing of a valve is provided.

The present invention according to another aspect relates to a pressurized water reactor in which a steam generator is connected to a steam generator by a primary cooling system including a high-temperature side pipe and a low-temperature side pipe. An apparatus for controlling the concentrations of B and Li components to a specified value, comprising: a measurement cell disposed in a measurement field of the B and Li components set on a high temperature side of the primary cooling system; A pulse laser for plasma generation and a pulse laser for excitation, which irradiate the cooling water with a pulse laser beam for plasma generation and a pulse laser beam for excitation of the B and Li components, respectively, and irradiation of the pulse laser beam for plasma generation Calculating means for calculating the actual value of the concentration of the B and Li components based on the emission intensity emitted from the B and Li components by the irradiation of the excitation pulse laser beam; A control valve for a B, Li component adjustment line connected to the low temperature side pipe of the cooling system; and when the actual value of the concentration of the B, Li component is determined to be an abnormal value, the actual value is set to the specified value. And control means for controlling the opening and closing of the control valve so as to return to the normal state.

Specifically, laser light is applied in two stages (LBS method) to improve the analysis accuracy for the B and Li components. Pulsed laser light for plasma generation is condensed / injected into the reactor cooling water, the components in the reactor cooling water are turned into plasma, and after a certain period of time after the plasma is generated, the plasma is introduced into the plasma induced by the laser light. Further, a pulse laser beam for excitation is incident, and the B and Li components existing in the plasma are laser-excited. B, Li excited by irradiation of pulsed laser light for plasma generation and pulsed laser light for excitation
The emission intensity of the component is detected using a photodetector, and B,
By correcting the emission intensity of the Li component by the component composition present in the plasma part, the B and Li components contained in the reactor cooling water as a sample can be immediately and directly quantified to a trace level on the order of ppb.

Further, the present invention provides a measuring cell arranged in a measuring field so as to allow the flow of water and the penetration of laser light,
Pulse energy of 10 to 40 mJ for water in the measurement cell
A plasma generation laser that emits a plasma generation pulse laser light, an excitation laser that emits the excitation pulse laser light of the detection target component contained in the water in synchronization with the plasma generation pulse laser light, Calculating means for calculating an actual value of the concentration of the detection target component based on the intensity of light emission emitted from the detection target component by the irradiation of the plasma generation pulse laser light and the irradiation of the excitation pulse laser light. To provide a concentration measurement system. Here, as described in claim 7, it is preferable that the emission interval between the pulse laser beam for plasma generation and the pulse laser beam for excitation is in the range of 1 μs to 13 μs. Further, as described in claim 8, 0.1 to 1 μs after irradiation of the pulse laser light for plasma generation or the pulse laser light for excitation, the component to be detected is re-excited with a wavelength width of 0.1 hm or less. It is preferable to further include a wavelength tunable laser that emits a laser beam adjusted to a desired wavelength (LIF method).

Further, it is preferable that the calculation means is a computer, and the emission intensity emitted from the detection target component by the irradiation of the excitation pulse laser beam is corrected based on an emission line emitted from oxygen atoms.

According to the present invention, the measuring cell is substantially hexahedral, and the first surface on which the plasma generating pulse laser beam and the excitation pulse laser beam are incident has a light transmitting surface through sealing means. A glass is provided, and a laser trap plate is provided on a second surface facing the first surface via a sealing means, and the laser trap plate is opposed to the second surface except for the first surface and the second surface.
The surface is provided with an inlet and an outlet that allow the flow of the water, and the other two opposing surfaces are provided with a light transmitting glass that transmits the plasma light and the light emission via a sealing unit.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. Further, as will be understood from the following description, the present invention is not limited to this embodiment, and various modifications are possible.

FIG. 1 schematically shows a control system of a pressurized water reactor plant to which the method and the apparatus according to the present invention are applied. In a solid containment vessel 1, a steam generator 2 and a reactor 3 are provided. Is arranged. The primary cooling water sent into the reactor 3 by the cooling water pump 5 provided in the pipe 8 is heated to a high temperature and a high pressure, enters the inlet side 2a of the water chamber of the steam generator 2 via the pipe 6, and While flowing through the many heat transfer tubes 2b, the water supplied from the pipe 7 is heated and cooled, and exits the steam generator 2 from the outlet side 2c of the water chamber. Then, the coolant is circulated again to the nuclear reactor 3 by the cooling water pump 5.

The feed water heated in the steam generator is turned into steam and supplied to a steam turbine (not shown) via a pipe 9. Also, the steam generator 2
Is provided with a pressurizer 4 for maintaining the cooling water in a pressurized state exceeding the saturation pressure in order to suppress the boiling of the cooling water in the reactor core.

An extraction line 10a for extracting a part of the cooling water upstream of the cooling water pump 5 is connected to the low-temperature side piping 8 constituting the primary cooling system, and a part of the cooling water pump A chemical volume control system 10 including a filling line 10b returning to the pipe 8 on the downstream side of the pipe 5 is connected. A desalting tower 11 and a volume control tank 12 are provided on an extraction line 10a of the chemical volume control system 10, and a boric acid tank 14, a primary chemical tank 15 and the like are provided on a filling line 10b in addition to a filling pump 13. Provided, chemical volume control system 1
The functions of No. 0 are refilling of the cooling water into the primary cooling system, removal of corrosion products and fission products in the cooling water, adjustment of boric acid concentration, and the like. The control valve 37 is connected to the extraction line 10a.
Although the operation is also provided, its operation will be described later.

In such a pressurized water reactor plant,
According to the present invention, for example, a device for managing or controlling the concentration of the B and Li components in the primary cooling water includes a device for generating a pulse laser beam and irradiating the cooling water of the primary cooling system with information obtained by the irradiation. Finally, there are provided an apparatus for calculating the B and Li component concentrations, and an apparatus for adjusting the B and Li amounts of the primary cooling system based on the calculated B and Li component concentrations. In FIG. 1, the measurement site of the device for irradiating the cooling water with the laser beam is indicated by a symbol, for example, in the middle of the high-temperature side pipe 6 of the primary cooling system or on the outer peripheral surface of the liquid phase portion of the pressurizer 4. Can be set to position.

Next, FIG. 2 shows an outline of an apparatus 20 for managing or controlling the B and Li component concentrations of, for example, primary cooling water according to the present invention. In FIG.
Is used to focus the pulsed laser light emitted by the pulse laser 21 for plasma generation on the reactor cooling water in a measurement cell provided in the measurement place 25 using mirrors 22, 23, a lens 28, and the like. The chemical species present in the cell is turned into plasma as illustrated in FIG. The laser output of the pulse laser 21 for plasma generation is set to 10 to 40 mJ in the embodiment of the present invention. FIG. 10 shows the experimental results of the laser output and the signal intensity in the case of Li. From these results, it is preferable that the laser output be set to 10 to 40 mJ so as to be suitable for plasma in a liquid. You can see that there is. Further, in synchronization with the emission of the laser light from the pulse laser 21 for plasma generation, the output of the pulse laser 26 for selective excitation of B and Li for increasing the emission intensity of the B and Li components in the cooling water after a certain period of time, As described above, the laser-induced plasma via the mirrors 22 and 23 and the lens 28 is newly incident via the mirror 27 and the like as shown in FIG. FIG. 11 shows the experimental results of the present invention showing the relationship between the emission interval and the signal intensity of the plasma generation pulse laser beam and the excitation pulse laser beam for the case of Li, where the emission interval or the pulse interval is 1 μs to 13 μs. And preferably 1.2
μs to 8.2 μs, more preferably 1.8 μs to 6.0 μs
s. Note that the units are omitted from the signal strengths on the vertical axes in FIGS. 10 and 11 because this may be considered as a signal strength ratio.

After detecting the plasma light generated by the laser light for plasma generation and identifying the component composition of the plasma part, the emission intensity of the B and Li components excited by the irradiation of the B and Li excitation pulse laser light is obtained. Is detected using a spectrometer and a detector. That is, in FIG. 2 and FIG. 3, the light emitted by B and Li excited by the above-described plasma light emission and the component excitation laser light is condensed by the lenses 29a and 29b, and the respective lights are converted into the optical fibers 30a and 30b. And enters the spectroscopes 31a and 31b. A part of the light reflected by the mirror 23 is converted into a laser output by the power meter 33,
4b. The personal computer 34b is connected to the detector 32b and also to another personal computer 34a. The personal computer 34b outputs data to a monitor (not shown) and displays the Li and B concentrations as digital values, for example, every 10 minutes. can do. The emission spectra emitted from the B and Li components are measured by the spectrometer 31b and the detector 3b.
2b, and sent to the personal computer 34b, where the peak intensities I _B and I _{Li of} Li and B are read. On the other hand, the measurement of the emission spectrum of oxygen (O) is performed by the personal computer 34a based on the input from the spectroscope 31a and the detector 32a, the O peak intensity _IO is read, and the read O peak intensity is read. _IO is sent to the personal computer 34b. Each signal is thus transferred to computer 34b, where O
The corrected peak intensities I _Li * and I _B * obtained by taking the ratio of the peak intensities I _B and I _{Li to} the peak intensities I _O are obtained, and the slopes of the Li calibration curves fLi and B calibration curves are calculated. By multiplying by fB, respectively, Li concentration (CLi) and B concentration (CB) can be obtained. As an example, FIG.
The emission spectrum of a Li aqueous solution is illustrated.

In this way, the component composition of the measurement field 25 is obtained from the signal of the plasma emission, the emission intensity is corrected based on the information, and the concentrations of the B and Li components existing in the measurement field 25 are calculated. As described above, by correcting the emission intensity of the B and Li components with the emission line of oxygen, which is the component composition of the plasma portion, the B and Li concentrations in the reactor cooling water can be measured with high accuracy down to the ppb order. 35 is a well-known synchronizer for synchronizing the oscillation of the pulse laser 21 for plasma generation and the pulse laser 26 for B and Li selective excitation with the operation of the detectors 32a and 32b.

Examples of the wavelengths of the pulse laser light for plasma generation and the pulse laser light for component excitation used in the present invention are shown below, which are used only because YAG lasers can be easily obtained at low cost. It goes without saying that other laser light may be used. Laser wavelength for plasma and component excitation: 1064 nm (fundamental wave of YAG laser) 532 nm (second harmonic of YAG laser) or 355 nm (third harmonic of YAG laser)

As can be seen from the above description, the present invention combines the LBS method and the LIF method. This combination makes it possible to eliminate the respective disadvantages. Specifically, since the temperature of a local place is raised to 10000 ° C. to 20,000 ° C. by the first plasma generation laser beam, almost all chemical species are in an atomic state. At this point, it is not necessary to consider the change in the excitation wavelength due to the bonding state of the chemical species. The B and Li concentrations can be changed only by injecting a laser beam that excites the plasma B and Li atoms. We can satisfy measurement. That is, LBS
Is a system that uses the two-stage method.
The detection sensitivity is greatly improved compared to the case of the first step of the method (3.
About 5 digits from the first digit).

Next, returning to FIG. 1, an application example of the present invention in a nuclear power plant will be described. As described above, a part of the high-temperature side pipe 6 of the primary cooling system or the pressurizer 4
A measurement field 25 is set on the outer peripheral surface of the liquid phase portion of
A two-stage method for controlling the concentration of B and Li components or a component concentration measuring system 20a (a portion surrounded by a chain line in FIG. 2) of the apparatus 20 is introduced. B, L in reactor cooling water
The i-concentration needs to be constantly maintained at a certain specified value due to circumstances such as reactor control. Therefore, the control device 20 for the B and Li component concentrations is linked to the chemical volume control system 10 so that
The necessary dilution / concentration and removal amounts of the B and Li components are calculated based on the actual measured value of the i concentration and the predetermined value to be maintained, and displayed to the nuclear power plant operator.

That is, the analysis results obtained in accordance with the above-described measurement procedure are displayed on a control panel indicating section (not shown) which can be arranged in the central control room 36 of the nuclear power plant, and the concentration is further displayed. 36 computers 34a, 34
b, Li, B and Li are compared and evaluated with the concentration reference values at the time of measurement.
When it is determined that the removal / concentration operation is necessary, not only the specific indication value of the operation amount is displayed again on the control panel indication portion of the central control room 36, but also the chemical volume is determined based on the indication value. The control valve 37 provided on the extraction line 10a of the control system 10 is opened and closed to control the amount of water flowing through the extraction line 10a. That is, when the measured or detected concentration value is lower than the lower limit of the set range, the control valve 37 is opened, and when the measured or detected concentration value is higher than the upper limit of the set range, the control valve 37 is opened.
Close.

As described above, the LBS two-stage system B, Li
The measurement field of the component concentration measurement system 20a is set to the high temperature side pipe 6 of the primary cooling system of the reactor, and is connected to the low temperature side pipe 8 of the primary cooling system based on the computer processing of the analysis result of the measurement system 20a. By controlling the control valve 37 provided in the cooling water extraction line 10a of the chemical volume control system 10, real-time measurement of the B and Li component concentrations in the reactor cooling water becomes possible, and the B and Li
By being able to constantly process the concentration value online, it is possible to more efficiently operate the reactivity control and water quality management of the reactor, which also leads to shortening the period of the process such as periodic inspection.

In this case, the measuring cell 4 provided in the measuring field
As 0, those shown in FIGS. 5 and 6 are preferable. 5 and 6, the measuring cell 40 is a substantially regular hexahedron, and in the embodiment, the inlet-side flow pipe 41 of the cooling water, usually 70-80 ° C., which is the sample water, is provided on the two upper and lower surfaces facing each other.
a, the outlet side flow pipe 41b is attached (FIG. 6), and the surface on which the pulse laser beam for plasma generation and the pulse laser beam for excitation are incident is made of rubber or plastic which is sealing means or vibration preventing means. A light transmitting glass 43 is provided via an O-ring 42 as described above. A laser trap plate 44 is provided on a surface facing the light transmitting glass 43 via a similar sealing means 42. The laser trap plate 44 is preferably a Teflon plate having a high trapping effect, and the measurement cell main body and the flow pipe are preferably made of stainless steel. On the other two opposing surfaces, light transmitting glasses 45 and 4 for transmitting plasma light and light emission are provided.
6 are provided via similar sealing means 42 (FIG. 5).

As shown in FIG. 4, in order to further improve the measurement sensitivity, the wavelength width is 0.1 hm or less 0.1 to 1 μs after the irradiation of the plasma generation pulse laser beam or the excitation pulse laser beam. And a wavelength tunable laser 50 for irradiating a laser beam adjusted to a wavelength for exciting the detection target component. The wavelength tunable laser 50 is also connected to the synchronizer 35, and the laser light from the wavelength tunable laser 50 irradiates the cooling water in the measurement cell via the mirrors 51 and 52 and the above-mentioned mirrors 22 and 23. This LBS /
If the LIF combined method is used, the detection sensitivity can be further improved. B, Li selective excitation laser wavelength B: 208.89 nm or 249.68 nm Li: 274.12 nm, 323.26 nm or 67
0.78

[0035]

According to the present invention, in a nuclear reactor having a cooling system, a method for controlling the concentration of a component to be detected in cooling water of the cooling system to a specified value, wherein the component to be detected is added to the cooling system The measurement field is set, and the cooling water of the measurement field is irradiated with the pulse laser beam for plasma generation, and the concentration value of the detection target component is determined based on the plasma light generated by the irradiation of the pulse laser beam for plasma generation. Detecting and controlling the cooling water injection control valve of the cooling system by a concentration signal representing the concentration value. Further, according to the control method of the present invention, a measurement field for the component to be detected is set in the cooling system, and the pulse laser light for plasma generation and the pulse laser light for excitation of the component to be detected are synchronized with the cooling water in the measurement field. Detecting the concentration value of the detection target component based on the plasma light generated by the irradiation of the plasma generation pulse laser light and the emission intensity emitted from the detection target component by the irradiation of the excitation pulse laser light. Then, the cooling water injection control valve of the cooling system is controlled to open and close by a concentration signal representing the concentration value. Therefore, according to the present invention, the concentration value of the cooling system can be constantly processed on-line, so that the reactivity control and water quality management of the reactor can be operated more efficiently. Also leads to.

Further, the worker in charge of water quality control of the reactor cooling water can avoid the possibility of exposure to radioactive corrosion products contained in the sample during sampling, transporting the sample, and analyzing the sample. It greatly contributes to the health management of people. Furthermore, the establishment of the above-mentioned concentration measurement using a laser eliminates the time required for collecting a working sample, transporting it to an analyzer, and measuring itself in the conventional method, thereby reducing the time required for B, Li in the reactor cooling water. It becomes possible to grasp the concentrations of the components in real time, and work related to concentration management becomes more efficient.

If the pulse energy of the pulse laser beam for plasma generation emitted to the water in the measuring cell is set to 10 to 40 mJ as in the present invention, the detection target component in the cooling water can be reduced. The energy level is suitable for detection, and components in the cooling water can be effectively detected. As in the embodiment of the present invention, the measurement sensitivity is improved by setting the emission interval between the plasma generation pulse laser beam and the excitation pulse laser beam in the range of 1 μs to 13 μs. Further, as in the embodiment of the present invention, the wavelength is adjusted to a wavelength that excites the detection target component with a wavelength width of 0.1 hm or less 0.1 to 1 μs after the irradiation of the plasma generation pulse laser light or the excitation pulse laser light. If a wavelength tunable laser for irradiating the laser light is provided, the measurement sensitivity can be further improved.

Further, the measurement accuracy can be further improved by correcting the emission intensity emitted from the detection target component by the irradiation of the excitation pulse laser beam based on the emission line emitted from the oxygen atom.

According to another aspect of the present invention, the measurement cell is provided with a laser trap plate via a sealing means on a surface opposed to a surface on which the plasma generation pulse laser beam and the excitation pulse laser beam are incident. Since it is provided, the laser light can be trapped effectively, and the sealing means can prevent water leakage and absorb vibration.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a pressurized water reactor plant to which a method and an apparatus for controlling the concentration of a detection target component according to an embodiment of the present invention are applied.

FIG. 2 is a schematic diagram showing the apparatus for measuring the concentration of a component to be detected according to the present invention.

FIG. 3 is an explanatory diagram illustrating a procedure executed by the density control device of FIG. 2;

FIG. 4 is a schematic diagram showing an apparatus for measuring the concentration of a detection target component with higher sensitivity according to the present invention.

FIG. 5 is a cross-sectional view of a measurement cell used in the concentration control devices of FIGS. 2 and 4.

FIG. 6 is a side view of a measurement cell used in the concentration control device of FIGS. 2 and 4.

FIG. 7A is a conceptual diagram of the measurement principle of the present invention showing an LBS application process, and FIG. 7B is a LIF application process.

FIG. 8 is a chart showing the relationship between the wavelength and the intensity (%) of the emission spectrum of an aqueous Li solution.

FIG. 9 is a table showing the relationship between the elapsed time from YAG laser irradiation and the signal intensity in the case of Li.

FIG. 10 is a chart showing a relationship between laser output and signal intensity in the case of Li.

FIG. 11 is a table showing a relationship between a pulse interval and a signal intensity in the case of Li.

FIG. 12 is an explanatory diagram illustrating a conventional B, Li concentration measurement procedure in a nuclear power plant.

[Explanation of symbols]

2 steam generator, 3 pressurized water reactor, 4 pressurizer, 6
... High temperature side piping of primary cooling system, 8 ... Low temperature side piping of primary cooling system, 10 ... Chemical volume control system, 10a ... Extraction line, 10
b: filling line, 20: concentration control device, 21: pulse laser for plasma generation, 25: pulse field for measurement, 26: pulse laser for selective excitation of B and Li, 34a, 34b: computer (calculation means), 37: control valve, 40 ... Measurement cell, 41a
... Inlet side flow pipe (inlet), 41b ... Outlet side flow pipe (outlet), 42 ... O-ring (sealing means), 43, 45, 4
6: quartz glass (light transmitting glass), 44: laser trap plate (Teflon plate), 50: tunable laser.

Continued on the front page (72) Inventor Hirofumi Hayashibara 2-1-1, Shinhama, Araimachi, Takasago-shi, Hyogo F-term in Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. 2G043 AA01 BA07 CA02 CA03 DA05 EA10 GA06 GA08 GA23 GB17 GB19 GB21 HA08 KA08 KA09 2G075 AA05 BA03 CA29 CA40 DA07 EA01 EA08 FA03 FA11 FB07 FC12 FC14 GA15 GA16 GA21

Claims (12)

[Claims] In a nuclear reactor having a cooling system, a method for controlling a concentration of a detection target component in cooling water of the cooling system to a specified value, wherein a measurement field of the detection target component is set in the cooling system. Irradiating the plasma generation pulse laser light to the cooling water of the measurement site, and calculating the actual value of the concentration of the detection target component based on the emission intensity emitted from the detection target component by the irradiation of the plasma generation pulse laser light. Detecting, based on computer processing of the actual value and the specified value,
A concentration control method for a detection target component, wherein a control valve of a detection target component adjustment line connected to the cooling system is opened and closed. 2. An apparatus for controlling a concentration of a component to be detected in cooling water of a cooling system to a specified value in a reactor having a cooling system, wherein a measurement field of the component to be detected set in the cooling system is provided. A measurement cell arranged in the cell, a plasma generation pulse laser for irradiating the plasma generation pulse laser beam to the cooling water of the measurement cell, and an emission intensity emitted from the detection target component by the plasma generation pulse laser beam irradiation. Calculating means for continuously calculating the actual value of the concentration of the detection target component based on the determination means, and determining means for determining whether the actual value of the concentration of the detection target component is acceptable with respect to the specified value. A control valve for a detection target component adjustment line connected to the cooling system, and when the actual value of the concentration of the detection target component is determined to be an abnormal value, the actual value returns to the specified value. Control means for controlling the opening and closing of the control valve as described above. 3. A pressurized water reactor connected to a steam generator by a primary cooling system comprising a high-temperature side pipe and a low-temperature side pipe, wherein the concentrations of B and Li components in the cooling water of the primary cooling system are controlled to specified values. Cell for measuring the B and Li components set on the high-temperature side of the primary cooling system, and irradiating the cooling water of the measurement cell with a pulse laser beam for plasma generation. A pulse laser for generating plasma, a calculating means for calculating an actual value of the concentration of the B and Li components based on an emission intensity emitted from the B and Li components by irradiation of the pulse laser beam for generating plasma, and the primary cooling A control valve for a B, Li component adjustment line connected to the low-temperature side pipe of the system; and, when the actual value of the concentration of the B, Li component is determined to be an abnormal value, the actual value is the specified value. Control means for controlling the opening and closing of the control valve so as to return to the normal state. 4. A method for controlling a concentration of a component to be detected in cooling water of a cooling system to a specified value in a reactor having a cooling system, wherein a measuring field of the component to be detected is set in the cooling system. Irradiating the cooling water of the measurement site with a pulse laser beam for plasma generation, detecting the concentration value of the detection target component based on the plasma light generated by the irradiation of the pulse laser beam for plasma generation, And controlling the opening and closing of a cooling water injection control valve of the cooling system by a concentration signal representing the following. 5. A method for controlling a concentration of a component to be detected in cooling water of a cooling system to a specified value in a reactor having a cooling system, wherein a measuring field of the component to be detected is set in the cooling system. Irradiating the cooling water of the measurement site with a pulsed laser beam for plasma generation and a pulsed laser beam for excitation of a component to be detected in synchronization with each other, and irradiating the plasma light generated by the irradiation with the pulsed laser beam for plasma generation and the excitation Detecting the concentration value of the detection target component based on the emission intensity emitted from the detection target component by irradiating the pulse laser light for use, and controlling the opening and closing of the cooling water injection control valve of the cooling system by a concentration signal representing the concentration value. A method for controlling the concentration of reactor cooling water. 6. In a nuclear reactor having a cooling system, an apparatus for controlling the concentration of a detection target component in cooling water of the cooling system to a specified value, wherein a measurement field of the detection target component set in the cooling system is provided. A measuring cell disposed in the measuring cell, a plasma generating pulse laser and an exciting pulse laser that irradiate the cooling water of the measuring cell with the plasma generating pulse laser light and the pulse laser light for excitation of the component to be detected in synchronization with each other. The actual value of the concentration of the detection target component is continuously changed based on the plasma light generated by the irradiation of the plasma generation pulse laser light and the emission intensity emitted from the detection target component by the irradiation of the excitation pulse laser light. Calculating means for calculating, and determining means for determining whether the actual value of the concentration of the detection target component is acceptable for the specified value,
The control valve of the detection target component adjustment line connected to the cooling system, and when the actual value of the concentration of the detection target component is determined to be an abnormal value, the actual value returns to the specified value. Control means for controlling the opening and closing of the control valve,
Reactor cooling water concentration control device. 7. In a pressurized water reactor connected to a steam generator by a primary cooling system comprising a high-temperature side pipe and a low-temperature side pipe, the concentrations of B and Li components in the cooling water of the primary cooling system are controlled to specified values. A measurement cell arranged in a measurement field of the B and Li components set on a high temperature side of the primary cooling system; and a pulse laser beam for plasma generation with respect to cooling water of the measurement cell. A pulse laser for plasma generation and a pulse laser for excitation, each of which irradiates a pulse laser beam for excitation of B and Li components in synchronization with each other, and the irradiation of the pulse laser beam for plasma generation and the pulse laser beam for excitation , A calculating means for calculating the actual value of the concentration of the B and Li components based on the emission intensity emitted from the Li component, and B and B connected to the low temperature side pipe of the primary cooling system. A control valve for the Li component adjustment line, and a control for opening and closing the control valve so that the actual value returns to the specified value when the actual value of the concentration of the B and Li components is determined to be an abnormal value. And a control unit for controlling the concentration of the reactor cooling water. 8. A measuring cell arranged in a measuring field so as to allow flow of water and penetration of a laser beam, and a pulse laser beam for generating plasma having a pulse energy of 10 to 40 mJ for water in the measuring cell. A laser for generating plasma to be fired,
An excitation laser that emits an excitation pulse laser beam of the detection target component contained in the water in synchronization with the plasma generation pulse laser beam; a plasma beam generated by irradiation of the plasma generation pulse laser beam; And a calculating means for calculating an actual value of the concentration of the detection target component based on the intensity of light emitted from the detection target component upon irradiation with the pulse laser light for use. 9. An emission interval between the plasma generation pulse laser beam and the excitation pulse laser beam is 1 μs to 13 μs.
9. The concentration measurement system according to claim 8, wherein the concentration is in the range of s. 10. A laser having a wavelength width of 0.1 hm or less and adjusted to a wavelength at which the detection target component is re-excited 0.1 to 1 μs after irradiation of the plasma generation pulse laser light or the excitation pulse laser light. The concentration measuring system according to claim 8, further comprising a wavelength variable laser that emits light. 11. The computing means is a computer,
The concentration measurement system according to any one of claims 8 to 10, wherein the emission intensity emitted from the detection target component by the irradiation of the excitation pulse laser beam is corrected based on an emission line emitted from oxygen atoms. 12. The measurement cell is substantially a hexahedron, and a light transmitting glass is provided on a first surface on which the pulse laser beam for plasma generation and the pulse laser beam for excitation are incident via a sealing unit. A laser trap plate is provided on the second surface facing the first surface via sealing means, and the water flow is applied to the two surfaces facing each other except for the first surface and the second surface. 12. The method according to claim 8, wherein an allowable inlet and an outlet are provided, and a light transmitting glass transmitting the plasma light and the light emission is provided via sealing means on the remaining two opposite surfaces. Concentration measurement system.