JP2011174772A - Method and device for measuring grounding system noise propagation characteristic in nuclear power plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure electric characteristics between separated grounding points. <P>SOLUTION: This device is equipped with: a network analyzer for measuring an electric characteristic between grounding points; a coaxial cable for measurement for connecting each middle point between a sensor, a preamplifier, a motor and an inverter, and each grounding point to the network analyzer; and a short-circuit cable for short-circuiting a shield of each coaxial cable for measurement. Thus, the electric characteristics between separated grounding points can measure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and apparatus for measuring ground propagation characteristics of a nuclear power plant.

  Noise generated in the power system of a nuclear power plant propagates to the instrumentation system. For this reason, many noise countermeasures have been proposed and implemented. The main propagation mechanism of noise may be electrostatic induction, electromagnetic induction, wraparound via ground, radiated electromagnetic field, and the like.

  Static induction is due to stray capacitance between the power system and the instrumentation system. Electromagnetic induction is generated by induction by mutual inductance between the power system and the instrumentation system. The sneak through the grounding appears as noise in the instrumentation system when a part of the noise current flowing from the power system to the grounding system flows into a loop constituted by the instrumentation system and the grounding system. The radiated electromagnetic field is often a problem mainly at high frequencies, causing high frequency electromotive force in the instrumentation cable and eventually appearing as noise in the instrumentation system. However, if there is no stray capacitance and the instrumentation system is completely separated from the grounding system, no noise appears in the instrumentation system even if there is the above cause. This is because the instrumentation system itself does not have a loop through which a common mode current that causes noise flows.

  However, in reality, for safety reasons, the equipment installed in the plant and the storage case for instrumentation need to be grounded, and are connected to the grounding system through stray capacitance. For this reason, it is considered that the noise appearing in the instrumentation system also depends on the noise propagation characteristics of the grounding system. Conventionally, however, the quantitative discussion on this point has not been sufficiently conducted. By taking measures such as electrostatic induction shielding, electromagnetic induction shielding, suppression of radiated electromagnetic field, grounding power system and instrumentation system impedance increase measures, even if the ground propagation noise propagation characteristics are unknown, some measures are taken Because it was made. In this respect, the design method that mainly incorporates empirical rules has been the mainstream in the laying design of power systems and instrumentation systems.

  As an example of impedance measurement, Patent Document 1 discloses a DC bias application device for impedance measurement.

JP-A-2-17458

  The laying design that incorporates the rule of thumb becomes a safer design, which may increase the cost of laying work. Recently, from the viewpoint of reducing plant and instrumentation costs, optimization of the power system / instrumentation system is also desired. And it is desired to be able to evaluate the noise resistance countermeasure effect with higher accuracy. Noise propagation characteristics that are often unclear in the evaluation are noise propagation characteristics through the grounding system.

  Noise propagation characteristics through the grounding system can be estimated by clarifying the impedance network between the grounding. That is, the magnitude of the common mode current flowing through the power system connected to the grounding system and the current shunting from the power system to the instrumentation system are determined by the impedance value between the grounding points. If the common mode current flowing through the power system is large, the instrumentation system may be affected via the grounding system. In this case, the common mode current can be suppressed by applying the common mode filter to the power system cable.

  Here, there is a method to confirm the effect of the common mode filter quantitatively by experiment, but if the noise propagation characteristics of the grounding system and the impedance value of the impedance network between the grounding points are known, the analysis Evaluation is also possible. Moreover, the effect can be analytically confirmed by applying a common mode filter to the instrumentation system cable. For example, when trying to suppress noise with a common mode filter, if the effect is the same when applied to either a power system or an instrumentation system, the cable of the power system is thick and a large amount of current flows through the cable. Therefore, the cost can be reduced by applying the common mode filter to the instrumentation system. Such quantitative evaluation is possible by knowing the noise propagation characteristics of the grounding system and the impedance value of the impedance network between the grounding points.

  Among plant designs, the specifications and arrangement of grounded trunk lines are design matters. However, the actual grounding system is integrated with the steel frame of the building other than the grounding trunk line, and these must be taken into account in the evaluation of noise propagation characteristics. In order to make noise prediction by an analytical method, it is necessary to clarify what member is electrically connected to each ground point. However, the electrical connection of each grounding point becomes clear only after the building is built. And after the construction of the building, most of the electrical connections between the grounding points are covered with floors and walls, and it is impossible to see what members are involved by observing the connections. It is.

  That is, in order to know the noise propagation characteristics between the ground points, it is necessary to clarify the arrangement and the value of the impedance between the ground points. For this reason, it is necessary to measure the impedance between the ground points. Impedance measuring means includes an impedance analyzer and a network analyzer. The impedance analyzer can measure the impedance between two points. On the other hand, a network analyzer is commercially available that can simultaneously measure S parameters between four points. Since the place where the measurement can be performed is limited after the building is constructed, S parameter measurement is advantageous in that a large amount of information for impedance estimation can be obtained. The electrical characteristics described below refer to this impedance or S parameter.

  As a means for grasping the electrical characteristics between the ground points, a method of directly measuring the electrical characteristics between the ground points can be considered. As an electrical characteristic of the ground point, there is a ground resistance, and the measurement of the ground resistance is common. However, inductance is mainly important for the electrical characteristics for the purpose of noise evaluation, and conventional measurement techniques cannot be used in this respect. Conventionally, an impedance analyzer is used for measuring the inductance. Similarly, information on impedance can be obtained by S parameter measurement using a network analyzer.

  However, these measuring devices are mainly intended for measuring characteristics of electronic components having a terminal interval of about several centimeters, and are not suitable for impedance measurement between terminals where the distance between ground points is several tens of meters. It is necessary to keep the shield between the measurement terminals of the impedance analyzer and network analyzer at the same potential, but the problem is that if the distance between the terminals is long, as in a nuclear power plant, it cannot be kept at the same potential. there were.

  Further, Patent Document 1 does not suggest a solution when the distance between the terminals is long.

  Accordingly, an object of the present invention is to make it possible to measure the electrical characteristics between remote ground points.

  The present invention includes a network analyzer that measures electrical characteristics between ground points, a sensor, a preamplifier, a motor, and a coaxial cable for measurement that connects the network analyzer between the inverter and the ground point. A short-circuit cable for short-circuiting the shield of the coaxial cable is provided.

  According to the present invention, it is possible to measure the electrical characteristics between remote ground points.

It is a whole explanatory drawing of the noise propagation characteristic measurement between the power system of a plant, and an instrumentation system by a grounding system noise propagation characteristic measuring device. It is a calibration implementation block diagram of the coaxial cable for a measurement of a network analyzer. It is the block diagram which showed the detailed structure of the short circuit wire cable. It is the figure which showed the specific structural example of the frequency characteristic correction | amendment device. It is a graph which shows the inductance reduction effect of the short circuit wire obtained by simulation with the circuit model of FIG. It is a circuit model between ground of a power system and an instrumentation system, and is a figure for explanation of a procedure for converting S parameter into resistance and inductance. It is a figure for demonstrating the connection method for electrically isolate | separating a network analyzer from a grounding system.

  The following embodiments relate to a noise propagation characteristic measuring method and apparatus for evaluating noise characteristics propagating from a power system to an instrumentation system in a nuclear power plant or the like.

  The following examples are intended to measure the electrical characteristics between the grounds of the power system and the instrumentation system in the plant, and connect the network analyzer and the grounding point with a coaxial cable for measurement. The shield between coaxial cables is short-circuited with a short-circuit cable.

  Hereinafter, this embodiment will be described in detail. In this embodiment, a grounding system of a nuclear instrumentation system that measures neutrons in a reactor pressure vessel of an improved boiling water reactor (ABWR), and an internal pump drive mechanism for circulating a coolant of the reactor This is a grounding system noise propagation characteristic measuring device for measuring the electrical characteristics of a grounding system.

  FIG. 1 shows an apparatus configuration when the grounding noise propagation characteristic measuring apparatus of this embodiment is used for measuring electrical characteristics between the grounding system of the ABWR internal pump drive mechanism and the grounding system of the nuclear instrumentation system. Show.

  The reactor pressure vessel 1 is accommodated in the reactor containment vessel 8. Inside the reactor pressure vessel 1, ionization chambers 3A and 3B, which are sensors for measuring the amount of neutron flux, are accommodated inside the instrumentation tubes 2A and 2B. Near the legs of the reactor pressure vessel 1, internal pumps 4A and 4B for circulating the coolant in the reactor pressure vessel 1 are installed. The internal pumps 4A and 4B are configured to be driven by motors 5A and 5B which are driving units. These motors 5A and 5B are driven via a three-phase power source 12, an inverter 11, and power cables 6A and 6B. The inverter 11 serving as a control unit changes the frequency of the current supplied to the motor to change the rotation speed of the motors 5A and 5B. The power cables 6 </ b> A and 6 </ b> B penetrate the reactor containment vessel 8 through the penetration 9, and are installed outside the reactor containment vessel 8. The nuclear instrumentation system guides detection signals from the ionization chambers 3A and 3B to the preamplifier 13 via the signal cables 7A and 7B. The signal cables 7 </ b> A and 7 </ b> B are laid through the reactor containment vessel 8 through the penetration 10. The output of the preamplifier 13 is input to the neutron monitor 14 so that changes in the neutron flux can be observed every moment.

  In the power system, the casing of the inverter 11 is connected to the ground point 15, and the casing of the motor 5 </ b> A is connected to the ground point 16. On the other hand, in the instrumentation system, the housing of the preamplifier 13 is connected to the ground point 17, and the ionization chamber 3 </ b> A is connected to the ground point 18 via a stray capacitance (not shown).

  The network analyzer 20 for measuring the electrical characteristics between the grounding points has four ports, and each port and the grounding point are connected to the core wires of the measurement coaxial cables 21A to 21D. The shields of the measurement coaxial cables 21A to 21D are connected by short-circuit cables 22A, 22B, and 22C.

  The apparatus configuration for measuring electrical characteristics between plant grounds has been described above. Although only two internal pumps 5 are shown in the figure, 10 are actually provided. Further, only two ionization chambers 3 of the nuclear instrumentation system used for the neutron monitor in the activation region are shown, but there are actually ten systems, but they are omitted for the sake of easy explanation.

  In FIG. 1, noise generated from the inverter 11 flows through a loop including the power cable 6 </ b> A, the motor 5 </ b> A, the ground point 16, and the ground point 15. At this time, the grounding points 15 and 16 are also coupled to the grounding points 17 and 18 with low impedance. Therefore, a part of the noise also flows in a loop including the preamplifier 13, the signal cable 7A, the ionization chamber 3A, the grounding point 18, and the grounding point 17. A method for measuring this electrical coupling between grounds is described below.

  Next, the calibration procedure of the network analyzer 20 will be described, and it will be shown that it is necessary to introduce a short-circuit wire.

  FIG. 2 shows a calibration system of the network analyzer 20. Four ports are arranged in the network analyzer 20, and measurement coaxial cables 21 </ b> A to 21 </ b> D are connected to the calibrator 201. The calibrator 201 measures the electrical characteristics of the measurement coaxial cables 21A to 21D connected between the network analyzer 20 and the calibrator 201, and the measurement coaxial cables 21A to 21D are measured from the results of measuring the electrical characteristics between the grounds. Used to subtract the effect of. Here, S parameters are used as electrical characteristics. The S parameter includes a reflection coefficient and a transmission coefficient between the ports. For this reason, it is necessary to connect and disconnect necessary ports during calibration. This connection or disconnection command is issued via the calibration control cable 202. The calibrator 201 incorporates these switch circuits. The case of the calibrator 201 is shielded and connected to the shields of the measurement coaxial cables 21A to 21D. The case of the calibrator 201 itself is about 10 cm. That is, the shields of the four measurement coaxial cables 21A to 21D are short-circuited. On the other hand, when measuring the electrical characteristics between the grounds, the grounds are not housed in any case. Therefore, the shields of the measurement coaxial cables 21A to 21D have no connection destination. Moreover, there are many places where the distance between plant groundings is several tens of meters. The resistance and inductance of the measurement coaxial cables 21A to 21D may be larger than the values between the grounds, and it is extremely important to eliminate the influence.

  In this measuring device, the shield between coaxial cables is short-circuited in order to make the actual measurement system as close as possible to the calibration system. However, since the short-circuit wire also has a length exceeding several tens of meters, it is difficult to say that the short-circuit wire is short-circuited even if the shields are simply connected by metal wires. Here, the resistance of the short-circuit line can be reduced by increasing the thickness of the short-circuit line. However, even if the short-circuit line is thickened or the number of short-circuit lines is increased, it is difficult to dramatically reduce the inductance. Therefore, in this embodiment, the inductance is reduced by the following method.

  Details of configurations and functions of the short-circuit cables 22A to 22C shown in FIG. 1 will be described with reference to FIG.

  FIG. 3 is a diagram showing a detailed configuration of the short-circuit cable 22A connected from the grounding point 15 to the grounding point 17. The short-circuit cable 22A includes a short-circuit line 221 connecting the grounding points, a parallel-compensation compensation line 222, a toroidal core 223, a current detector 224 of the short-circuit line 221, a frequency characteristic correction unit 25 that applies frequency correction to the detection current, and a frequency correction post-correction. Are provided with an amplifier 226 for amplifying the above signal and a current limiting resistor 227 for preventing an excessive current from flowing through the compensation line. One end of the compensation line 222 is connected to the ground of the circuit of the frequency characteristic corrector 25 and the amplifier 226, so-called common. By passing a current in the opposite direction to the current flowing in the short-circuit line 221 through the compensation line 222, a voltage in the opposite direction is generated in the short-circuit line 221 with the same voltage as the voltage drop due to the inductance of the short-circuit line 221 by mutual induction. As a result, the voltage drop due to the inductance of the short-circuit wire 221 is eliminated, and as a result, there appears to be no inductance. The toroidal coil 223 has an effect of increasing the mutual inductance between the short-circuit wire 221 and the compensation wire 222. As a result, a large mutual inductance variation is eliminated by a slight misalignment between the parallel lines.

The combined transfer function G ₂ of the frequency characteristic corrector 25 and the amplifier 226 is shown below. A current limiting resistor 227 referred to as R _2. R ₂ includes the resistance of the compensation line 222 itself. The resistance of the short-circuit line 221 is denoted as R ₁ , the inductance is denoted as L ₁ , and the inductance of the compensation line 222 is denoted as L ₂ . The voltage between the ground point 15 and the ground point 17 is V ₁ . At this time, assuming that the current i ₁ that flows through the short-circuit line 221 and the current i ₂ that flows through the compensation line 222, these relations are (1).

In equation (1), S is a complex frequency. M is a mutual inductance between the short-circuit line 221 and the compensation line 222. When the inductance of the short-circuit line 221 is apparently 0, the voltage drop due to L ₁ of the short-circuit line 221 is equal to the induced voltage due to mutual induction.

Substituting (1) into equation (2), the combined transfer function G ₂ rewrites the mutual inductance M using the coupling coefficient k.

Assuming that the combined transfer function G ₂ is gain A ₀ and frequency characteristic G _u (f),

となる。周波数特性補正器２５で（５）式の特性を、増幅器２２６で（４）式の特性を実現すれば良いことが分る。

It becomes. It can be seen that the frequency characteristic corrector 25 can realize the characteristic of the expression (5) and the amplifier 226 can realize the characteristic of the expression (4).

  FIG. 5 is a result of obtaining the short-circuit line inductance by simulation when the cable length is 50 m in the configuration of the short-circuit cable 22A of FIG. The horizontal axis represents the frequency, and the vertical axis represents the ratio between the inductance of the short-circuit line 221 and the inductance when the inductance is reduced with the configuration of FIG. It can be seen that the configuration of FIG. 3 is reduced to 6 digits or less of the actual inductance of the short-circuit line 221.

FIG. 4 shows the configuration of the frequency characteristic corrector 25. The frequency characteristic corrector 25 includes an operational amplifier 251, a resistor 252, a feedback resistor 253, and a feedback inductance 254. If the resistor 252 is R ₀ , the feedback resistor 253 is R _f , and the feedback inductance 254 is L _f , the transfer function G (f) of the circuit of FIG.

となる。（６）式の第一項が低周波のゲインを決めており、１倍より大きい。図４の回路で周波数特性補正器２５を構成する場合、増幅器２２６のゲインを

It becomes. The first term in equation (6) determines the low frequency gain, which is greater than one time. When the frequency characteristic corrector 25 is configured by the circuit of FIG.

とすればよい。

And it is sufficient.

  By using the short-circuit cables 22 </ b> A to 22 </ b> C described above, it is possible to measure the electrical characteristics between the grounds with an accuracy close to that when calibrated by the calibrator 201.

  The measurement result is obtained as an S parameter consisting of the transmittance from each port to other ports and the reflectance to the same port.

  It is possible to calculate how, for example, the common mode current of the power system affects the instrumentation system using the noise propagation characteristic between the ground expressed by the S parameter. However, it is difficult to intuitively grasp the aspect of noise propagation from the S parameter. Therefore, in this embodiment, the resistance and inductance between the grounds are calculated based on the measured S parameter.

  FIG. 6 is a diagram showing the internal structure of the impedance network 30 between the grounds. The grounding points 15 to 18 shown in FIG. 1 are connected to five impedance blocks composed of combinations of resistances R01 to R05 between the grounds and inductances L01 to L05. A loop in which noise current flows through the grounding points 15 and 16 of the power system is calibrated, and a loop in which noise current flows through the grounding points 17 and 18 also exists in the instrumentation system. In addition, the noise current flowing through the power system is diverted to flow into the instrumentation system. It has a structure that can also express the difference in impedance viewed from each grounding point 15-18. In the S parameter measurement described above, the reflection coefficient of each port and the transmission coefficient between all ports can be measured. Since there are 4 ports, there are 16 measured S-parameters. By changing the values of the ground-to-ground resistors R01 to R05 and the ground-to-ground inductances L01 to L05, the ground-to-ground resistors R01 to R05 and the ground-to-ground inductances L01 to L05 that are closest to the measured S parameter are determined. See as circuit constants. This method is the same as a method for obtaining a general optimum solution.

  FIG. 7 shows a circuit configuration for separating the network analyzer 20 from the ground. The network analyzer 20 is usually used with the casing grounded. On the other hand, the impedance network 30 between the grounds to be measured in this embodiment is also grounded. For this reason, a part of the signal supplied from the measurement port of the network analyzer 20 returns to the network analyzer 20 through the ground. Signals returning through ground are not measured, resulting in a large measurement error. Therefore, in this embodiment, the network analyzer 20 is separated from the ground and measured.

  As shown in FIG. 7, the inter-ground impedance network 30 is grounded to a virtual ground point. The ground-to-ground impedance network 30 is grounded as a whole, but a slight voltage distribution or current distribution exists inside the network. Although the position of the true grounding point cannot be defined, a virtual grounding point is shown in the sense that it is grounded. A ground isolation impedance 31 is connected between this virtual ground point and the network analyzer 20. By connecting this impedance, a signal returning to the network analyzer 20 via the ground is suppressed. In this embodiment, a resistor is used as the impedance 31 for ground separation, but an inductor can also be used. It is also conceivable to use without connecting to the ground. In any method, the network analyzer 20 has a potential between the ground point and the ground point due to the separation from the ground. For this reason, a device such as a glove is devised so as not to directly touch the housing of the network analyzer 20 during measurement.

  By the above procedure, the resistances R01 to R05 are measured so that it is easy to grasp the ease of noise propagation based on the measurement of the electrical characteristics between the grounds in the plant, which has been difficult until now, and the measured values. In addition, estimated values of the inductances L01 to L05 can be obtained.

  As described above, in this embodiment, the network analyzer for measuring the electrical characteristics between the ground points, the sensor, the preamplifier, the motor, and the measurement coaxial cable for connecting the network between the inverter and the ground point are connected to the network analyzer. It is possible to keep the shield between the measurement terminals at the same potential by providing a short-circuit cable that short-circuits the shield of each measurement coaxial cable.

  In addition, the short-circuit cable is composed of a short-circuit line connecting the ground points, a compensation line that runs parallel to the short-circuit line, a toroidal core, a current detector for the short-circuit line, a frequency characteristic corrector that adds frequency correction to the detected current, It is possible to measure the electrical characteristics between the ground lines even if the short-circuit line becomes long by providing an amplifier for amplifying the current and a current limiting resistor for preventing an excessive current from flowing through the compensation line. Usually, when a short-circuit wire is used, the resistance can be reduced by increasing the wire diameter or bundling a large number of wires. However, the effect of reducing the inductance is small even if the line is simply thickened. Further, the inductance increases almost in proportion to the length of the short-circuit line.

  When a short circuit line exists independently, the electric current which flows into a short circuit line depends on the voltage and frequency between measurement terminals. On the other hand, if the short circuit has no inductance, the current does not depend on the frequency. The inductance of the short-circuit line is reduced by flowing a current for preventing the current flowing through the short-circuit line from having apparent frequency characteristics through the compensation line that runs parallel to the short-circuit line. Specifically, the current value detected by the short-circuit line current detection means (current detector) is taken out as a voltage signal, passed through the frequency characteristic corrector, further amplified and applied to the compensation line, and the current is supplied to the compensation line. . Since the compensation line and the short-circuit line run in parallel, the two lines are electrically connected by mutual inductance. A component that suppresses the current that flows due to the inductance of the short-circuit line can be supplied from the compensation line side, and a current that does not depend on the frequency between the measurement terminals can be supplied. As a result, the short-circuit wire can be realized with a characteristic having no inductance.

The specific effects of this embodiment are as follows.
(1) In this embodiment, since a procedure for estimating the resistance / inductance between the grounds from the measured S parameters is provided, intuitive information on the characteristics between the grounds can be obtained compared to the case of using only the S parameters. In addition to the ground-to-ground characteristics, it is possible to quickly determine the effect on the electrical characteristics, which has the effect of improving the electrical characteristics measurement performance.
(2) As shown in the present embodiment, the present invention can measure the electrical characteristics of a member separated from the measurement end, so that impedance measurement of a long ground wire, large-scale structure, etc. is possible. Enlargement of the surrounding area has an effect of improving electrical characteristics measurement.

  In the above embodiment, the internal pump has been described as the power system, but the present invention can also be applied to other power systems. For example, a motor-operated valve control mechanism that controls the opening and closing of a motor-operated valve provided on a pipe (a motor-driven valve driving unit and a motor-operated valve opening / closing control unit that controls the driving unit), a control rod inserted into a reactor pressure vessel The present invention can also be applied to a control rod position control mechanism that controls the position (a control rod drive unit and a control rod position control unit that controls the drive unit).

  The present invention may be used not only for grasping noise propagation characteristics between plant groundings, but also for monitoring characteristics changes of grounded trunk lines.

1 Reactor pressure vessel 2A, 2B Instrumentation tube 3A, 3B Ionization chamber 4A, 4B Internal pump 5A, 5B Motor 6A, 6B Power cable 7A, 7B Signal cable 8 Containment vessel 9, 10 Penetration 11 Inverter 12 Three-phase Power supply 13 Preamplifier 14 Neutron monitor 15, 16, 17, 18 Grounding point 20 Network analyzers 21A to 21D Measuring coaxial cables 22A to 22C Short-circuit cable 25 Frequency characteristic corrector 30 Grounding impedance network 31 Grounding separation impedance 201 Calibration 202 Control cable 221 for calibration Short circuit wire 222 Compensation wire 223 Toroidal core 224 Current detector 227 Current limit resistor 228 Compensation wire circuit ground 251 Operational amplifier 252 Resistor 253 Feedback resistor 254 Feedback inductance R01 to R0 Ground between the resistance L01~L08 ground between the inductance

Claims (4)

An instrumentation system comprising a sensor for measuring neutrons in a reactor pressure vessel, and a preamplifier to which a detection signal from the sensor is input;
A power system comprising an internal pump for circulating the coolant in the reactor pressure vessel, a motor for driving the internal pump, and an inverter for adjusting the rotational speed of the motor;
A grounding system noise propagation characteristic measuring device for a nuclear power plant that measures noise propagation characteristics flowing through the instrumentation system and the power system and a grounding point,
A network analyzer that measures electrical characteristics between ground points;
A coaxial cable for measurement that connects the sensor, the preamplifier, the drive unit, and the network analyzer between the control unit and the ground point,
A grounding noise propagation characteristic measuring apparatus for a nuclear power plant, comprising a short-circuit cable for short-circuiting a shield of each of the coaxial cables for measurement. A grounding noise propagation characteristic measuring apparatus for a nuclear power plant according to claim 1,
The power system includes an internal pump that circulates coolant in the reactor pressure vessel, a motor that drives the internal pump, and an inverter that adjusts the rotational speed of the motor. Grounding noise propagation characteristic measurement device for power plants. A grounding noise propagation characteristic measuring apparatus for a nuclear power plant according to claim 1,
The short-circuit cable includes a short-circuit line connecting ground points, a compensation line that runs parallel to the short-circuit line, a toroidal core, a current detector for the short-circuit line, a frequency characteristic corrector that adds frequency correction to the detected current, A grounding system noise propagation characteristic measuring apparatus for a nuclear power plant, comprising: an amplifier for amplifying a signal; and a current limiting resistor for preventing an excessive current from flowing through the compensation line. An instrumentation system comprising a sensor for measuring neutrons in a reactor pressure vessel, and a preamplifier to which a detection signal from the sensor is input;
An internal pump that circulates the coolant in the reactor pressure vessel, a motor that drives the internal pump, and a power system that includes an inverter that adjusts the rotational speed of the motor,
A network analyzer that measures electrical characteristics between ground points;
The sensor, the preamplifier, the motor, and a coaxial cable for measurement connecting the network analyzer between the inverter and the ground point,
A method for measuring a grounding noise propagation characteristic of a nuclear power plant including a short-circuit cable for short-circuiting a shield of each of the coaxial cables for measurement,
A grounding-system noise propagation characteristic measuring method for a nuclear power plant, wherein resistance and inductance between grounds are calculated based on S parameters measured by the network analyzer.

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