JPH0353570B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a water leakage detection device, and in particular, to detecting water leakage from equipment where a liquid metal region and a water region are located close to each other at an early stage while maintaining high reliability. This invention relates to a water leak detection device. [Prior art] Liquid sodium, which is a liquid metal, is an excellent coolant in fast neutron reactors, but because it is chemically extremely active, it is difficult to use steam in nuclear power plants using the above reactors. This prevents water and steam from leaking into the sodium side from the steam pipe of the generator and causing a sodium-water reaction, in the unlikely event that
Early detection of this reaction when it occurs is essential in plant design. Therefore, in the past, when a small-scale water leakage accident occurred in a sodium-heated steam generator, a metal diffusion membrane type hydrogen detection method has been adopted as the most suitable means for detecting water leakage. This detection method uses a metal membrane with a high hydrogen permeability coefficient, such as nickel, as a hydrogen diffusion membrane, and guides the hydrogen produced when sodium and leaked water react into a vacuum through the diffusion membrane. This is a method of monitoring and detecting water leaks. FIG. 1 shows the overall configuration of a conventional water leak detection device. Sodium flowing through the sodium system 1 is shielded from the steam system 3 by piping in the steam generator 2. Any part of the sodium stream is transferred from the outlet of the steam generator 2 to the valve 4 by means of an electromagnetic pump 5.
a, an electromagnetic flowmeter 6, a heater 7, and then taken into a detector 8, and then returned to the original sodium loop through a valve 4b. The electromagnetic flowmeter 6 measures the sodium sampling flow rate. Detection section 8
A nickel membrane 9 is installed inside, and sodium flows inside the nickel membrane 9, and the outside is kept in a vacuum state by a vacuum pump 11. If a water leak occurs in the steam generator 2 in this state, hydrogen generated by the sodium-water reaction, that is, Na + H ₂ O → NaOH + 1/2 H ₂ , will be released from the valve 4 along with sodium.
a, passes through the electromagnetic pump 5, electromagnetic flowmeter 6, and heater 7, and reaches the inside of the detection section 8. Since the nickel film 9 in the detection section 8 selectively diffuses and permeates hydrogen, hydrogen comes out into the vacuum system 10. The concentration of hydrogen introduced into the vacuum system 10 is measured based on the degree of vacuum detected by a gauge 12 and a vacuum gauge 13. This hydrogen concentration signal 14 is processed by a signal processing device 15.
be taken into account. An example of the configuration of a conventional signal processing device 15 is shown in FIG. The hydrogen concentration signal 14 is sent to the comparators 18a, 18
b, it is compared with the alarm set value C _H and the trip set value C _HH , respectively. Hydrogen concentration input is alarm set value
When the value exceeds the trip set value C _H , the amplifier 19a outputs the alarm output signal 16, and when the value exceeds the trip set value C _HH ,
Amplifier 19b outputs trip output signal 17. FIG. 3 shows the relationship between the temporal change in hydrogen concentration and the alarm set value and trip set value in the prior art. Hydrogen concentration C slowly rises to alarm set value
An alarm output signal 16 is output when T _H reaches _CH , and a trip output signal 17 is output at T _HH when the trip set value C _HH is reached. [Problem to be solved by the invention] In such a conventional water leak detection device,
The alarm output signal 16 and the trip output signal 17 are each issued when one predetermined setpoint concentration is exceeded. In this case, if the concentration signal 14 fluctuates due to small fluctuations in the hydrogen concentration in sodium during operation, disturbances due to changes in process quantities such as sodium flow rate and temperature, electrical noise, etc. and reaches the alarm set value or trip set value, There is a drawback that an alarm output signal or a trip output signal is erroneously output even though the hydrogen concentration has not actually increased. Another disadvantage is that if the concentration output changes very slowly, it takes a very long time to reach the alarm set value and the trip set value. These shortcomings in the prior art have caused major problems in terms of reliability and responsiveness as means for monitoring abnormalities in equipment during the operation of nuclear power plants. In order to solve this problem, for example,
As in No. 37683, a method has been proposed in which a physical quantity that changes due to leakage is differentiated and an abnormality is determined when the differential value (rate of change) exceeds a set value. With this method, abnormalities can be detected quickly without being affected by slow changes in plant operating conditions. However, since the differential value of the physical quantity is used, there is a possibility that disturbances, electrical noise, etc. due to sudden changes in plant conditions may be detected as changes in the physical quantity itself, and an erroneous determination may be made. Related prior art includes, for example, Japanese Patent Publication No. 53-43637, Japanese Patent Application Laid-open No. 141693-1983, and Japanese Patent Publication No. 52-1989.
-5590, Utility Model Application No. 53-153988, etc. Among these, Japanese Patent Publication No. 53-43637 uses a differential circuit to determine the amount of change at one point in time, and detects hydrogen based on that data. In this example,
Although it includes a first-order delay circuit that removes noise of several tens of Hz or higher contained in electrical signals, it has not been possible to remove noise that changes slowly to the same extent as the detection signal. In addition, JP-A No. 55-141693 discloses that for detection points (data) placed at multiple positions, the numbers of adjacent locations are the same, and when multiple signals of the same number are detected, based on majority decision, Identify the location of the leak. In this example, the majority vote is taken, so it seems that the position can be determined reliably, but
When noise enters the system, there is a high possibility that the same number of detectors will simultaneously make false detections, so it cannot be said that the reliability is necessarily high. Further, in Japanese Patent Application Laid-open No. 52-5590, flow rate change measurement data is obtained at two points at regular time intervals, and an abnormality is determined when the deviation of the change exceeds a set value. In this example as well, there is no consideration for noise contamination, and in order to use it in the field of application like the present invention,
I feel anxious. In Utility Model Application Publication No. 53-153988, all detection results are input to an AND circuit, and a conclusion is reached based on the coincidence of all the signals. If it rises,
There was a problem in which effective judgment could not be made at the point of a temporary decline. An object of the present invention is to provide a water leak detection device that can detect water leaks from equipment at an early stage while maintaining high reliability by eliminating the effects of disturbances, electrical noise, etc. caused by sudden changes in a plant. . [Means for Solving the Problems] In order to achieve the above object, the present invention prevents water leakage from the water region to the liquid metal region of a device in which the liquid metal region and the water region exist in close proximity to each other by reducing hydrogen concentration. A water leak detection device that detects hydrogen concentration data based on a change in water leakage, the method comprising: means for capturing hydrogen concentration data at each point in time of a predetermined interval; means for determining changes in hydrogen concentration at each time interval from hydrogen concentration data; means for comparing the plurality of changes in hydrogen concentration with a predetermined upper limit value; and determining the presence or absence of water leakage by taking a majority vote on the results of the comparison. The present invention proposes a water leakage detection device that includes means for determining, and means for successively changing the reference time of the time interval and repeating the above procedure. The present invention also provides a water leakage detection device that detects water leakage from the water region to the liquid metal region of a device in which a liquid metal region and a water region are located close to each other, based on a change in hydrogen concentration. means for acquiring hydrogen concentration data for each time interval; means for determining a change in hydrogen concentration for each time interval from hydrogen concentration data at both ends of at least three time intervals having the same length equal to or longer than the predetermined interval; means for comparing changes in the hydrogen concentration of the above with a predetermined upper limit value; means for determining the presence or absence of water leakage by taking a majority vote on the results of the comparison; and means for repeating the above procedure by successively changing the reference point in the time interval. This paper proposes a water leak detection device equipped with the following. [Function] In general, when detecting hydrogen concentration, in order to make it less susceptible to the effects of noise, etc., and to ensure that the expected change reaches a certain value in terms of detection sensitivity, the time width T should be set to a certain length. It is necessary to secure it. On the other hand, in order to quickly detect changes, it is better to capture a large amount of data by shortening the data capture time interval. However, as typified by the invention described in Japanese Unexamined Patent Publication No. 52-5590 mentioned above, when the time interval of data acquisition and the time width of calculating the amount of change in the physical quantity are the same T, In this case, a compromise must be made when the above two demands are balanced. In contrast, in the present invention, the time interval Δt for data acquisition and the time width ΔT for calculating the amount of change in hydrogen concentration do not necessarily match. That is, the time interval Δt for data acquisition and the time width ΔT for calculating the amount of change in a physical quantity are independently determined so as to satisfy the ideal requirements for each time width. For example, at least three time intervals ΔT ₀₁ , ΔT ₀₂ , ΔT ₀₃ , ΔT ₀₄ , . . . which have different lengths that are longer than a predetermined interval Δt and have the same reference time are adopted.
More specifically, ΔT ₀₁ =Δt, ΔT ₀₂ =2Δt, ΔT ₀₃
=3Δt, ΔT ₀₄ =4Δt, etc. As a result, while preventing malfunctions due to noise and the like, sensitivity can be sufficiently increased to quickly and accurately detect hydrogen concentration change trends that are about to be buried under background fluctuations. Note that the time width ΔT for calculating the amount of change is constant, and only the timing of data acquisition is T ₁ − T ₀ , T ₂ −
T ₁ , T ₃ −T ₂ , T ₄ −T ₃ , … or T ₃ −T ₀ , T ₄ −
Even when shifting sequentially like T ₁ , T ₅ −T ₂ , T ₆ −T ₃ , etc., data is acquired at a time interval Δt that is much shorter than the time width ΔT for calculating the amount of change, so
Based on the tendency of changes in the amount of change in data separated by a short time interval Δ, water leakage can be quickly determined by majority vote. [Embodiment] Next, an embodiment of the present invention will be described with reference to FIGS. 4 to 6. This embodiment is an example in which a change in hydrogen concentration calculated at regular intervals from a certain point in time is compared with a predetermined upper limit value of change to determine an abnormality. FIG. 4 is a block diagram showing the configuration of the signal processing device of this embodiment. The concentration signal 14 taken into the signal processing device 15 is first stored in the storage device M4. The contents of the storage device M4 are outputted to the subtractor 20a and the storage device M3, the contents of the storage device M3 are outputted to the subtracter 20b and the storage device M2, and the contents of the storage device M2 are outputted to the subtractor 20b and the storage device M2.
The contents of are outputted to the subtractor 20c and the storage device M1, and the contents of the storage device M1 are outputted to the subtractor 20d and the storage device M0. The contents of storage device M0 are output to subtracters 20a-20d. Each subtractor 20a
~20d performs the following calculation. Output of 20a = M4-M0 Output of 20b = M3-M0 Output of 20c = M2-M0 Output of 20d = M1-M0 The outputs of the subtracters 20a to 20d are stored in the storage device M1.
1 to M14. These storage devices M11~
The contents of M14 are output to the alarm setting circuit 23 and trip setting circuit 24, and are output to the comparators 21a to 21, respectively.
d, 25a to 25d and 3/4 logic circuits 22a and 22b as discriminators, which are used to output an alarm output signal 16 or a trip output signal 17. The above-described rewriting of the storage contents of the storage devices M0 to M4 and M11 to M14 is performed in response to timing pulses P0 to P5 from the pulse generator TPG. Figure 5 shows the data capture timing pulse P0~ which is output from the pulse generator TPG every cycle Δt.
The relationship between P5 is shown, where ΔT ₀ is the measurement value calculation cycle and ΔT ₁ is the pulse width. The pulse width ΔT ₁ is
The time width is sufficient to rewrite the contents of the storage devices M0 to M4 and M11 to M14. In FIGS. 4 and 5, when the timing pulse P4 for data acquisition is output at time Tn- ₁ , the concentration signal 14 is stored in the storage device M4, and then the subtracter 20a outputs the signal 20a. The calculation =M4-M0 is performed. After that, subtracters 20a-2
The output of 0d is stored in the storage devices M11 to M14 by the data retrieval timing pulse P5. In this case, the operations of the subtracters 20b to 20d have already been completed at another point in time, which will be described later. Here, in preparation for the next data acquisition and acceptance of calculations, it is necessary to leave the storage device M4 empty, so the following processing is performed on the contents of the storage devices M0 to M4. Contents of M0 → Delete Contents of M1 → Put in M0. Contents of M2 → Put into M1. Contents of M3 → Put into M2. Contents of M4 → Put in M3. Therefore, the timing pulse P for data acquisition is issued from the pulse generator TPG every cycle Δt.
0,, P1, P2, P3, . . . the contents of the storage device are rewritten. At this point, subtractor 2
The calculations of 0b to 20d are completed, and the system enters a standby state for inputting the new concentration signal 14 described above. Processing of data calculated and stored through the above operations will be described with reference to FIG. 6, which shows the relationship between changes in hydrogen concentration and temporal changes in each output. The vertical axis in Figure 6 is hydrogen concentration c, and the horizontal axis is time t, T ₀ ~ T ₁₀
represents the elapsed time for each measurement value calculation cycle ΔT ₀ . Note that the data from T ₀ to _{T 3} has already been stored in the storage device M.
The explanation will be made assuming that the data is stored in 0 to M3. When the concentration signal 14 is stored and calculated at time _T4 , the outputs of the subtractors 20a to 20d and the contents of the storage devices M11 to M14 are as follows. Output of 20a = M4-M0 = ΔC ₀₄ = M14 Output of 20b = M3-M0 = ΔC ₀₃ = M13 Output of 20c = M2-M0 = ΔC ₀₂ = M12 Output of 20d = M1-M0 = ΔC ₀₁ = M11 These The value is compared with the change width alarm set value ΔC _H by comparators 21a to 21d for the alarm output signal, and is compared to the change range alarm set value ΔC H for the trip output signal.
It is compared with the change width trip set value _ΔCHH at steps 5a to 25d. The outputs of the comparators 21a to 21d are "1" when the input value ≧ΔC _H. The outputs of the comparators _25a to 25d are "1" when the input value ≧ ΔC _HH . Since it is “0” when <ΔC _HH , the outputs of the comparators 21a to 21d with respect to the outputs of the storage devices M11 to M14 are as follows: M14=ΔC ₀₄ >ΔC _H →21a output=“1” M13=ΔC ₀₃ <ΔC _H → 21b output = “0” M12 = ΔC ₀₂ < ΔC _H → 21c output = “0” M11 = ΔC ₀₁ < ΔC _H → 21d output = “0”, and the output of the 3/4 logic circuit 22a is “0”
becomes. Therefore, no alarm output signal is issued. Next, looking at the calculation outputs at T ₆ , M14=ΔC ₂₆ >ΔC _H →21a output=“1” M13=ΔC ₂₅ >ΔC _H →21b output=“1” M12=C ₂₄ >ΔC _H → 21C output = “1” M11 = ΔC ₂₃ < ΔC _H → 21d output = “0”, and the output of the 3/4 logic circuit 22b is “1”
becomes. As a result, an alarm output signal is issued. At time _T9 , calculation outputs are obtained in the same manner for ΔC ₅₆ , ΔC ₅₇ , ΔC ₅₈ , and ΔC ₅₉ . _ΔCHH
can also be calculated in the same way as ΔC _H above. As a result of the above calculation, the alarm output signal 16 is output at time T ₆ , and the trip output signal 17 is output at time T _9.
will be output. FIG. 7 shows a modification of the signal processing device of this embodiment. In this example, the discriminator for the alarm output signal 16 and the trip output signal 17 is a 2/3 logic circuit 24a,
24b, and along with that, the storage device M
0 to M3, M11 to M13, subtractors 20a to 20
c, the number of circuits of the comparators 21a to 21c and 25a to 25c is three. The basic movement is the 4th
This is similar to the embodiment shown in the figure. Another embodiment of the water leak detection device according to the present invention is shown in FIGS. 8 and 9. The present embodiment is an example in which changes in concentration are measured at every fixed time interval ΔT ₀ and water leakage is determined based on trends in these multiple changes in concentration. FIG. 8 is a block diagram showing the configuration of the signal processing device of this embodiment. The concentration signal 14 input to the signal processing device 15 is input to the storage devices M21 to M24, the output of the storage device M21 is sent to the subtracters 20a and 20d, and the output of the storage device M22 is sent to the subtracter 20a.
and 20b, the output of the storage device M23 is sent to the subtracter 20
b to 20c, the output of the storage device M24 is the subtracter 2
They are input to 0c and 20d, respectively. Subtractor 20a~
In 20d, the following calculations are performed. Output of 20a = M22-M21 Output of 20b = M23-M22 Output of 20c = M24-M23 Output of 20d = M21-M24 The outputs of the subtracters 20a to 20d are stored in the storage device M31.
-M34, and the outputs of the storage devices M31-M34 are input to the alarm setting circuit 23 and the trip setting circuit 24. On the other hand, the output of the pulse generator TPG, which transmits pulses with a constant period, is sent to the timing pulse distributor TP1.
~Input to TP4, timing pulse distributor TP
The outputs of 1 to TP4 are stored in storage devices M21 to M24,
It is input into M31 to M34. FIG. 9 shows the relationship between changes in hydrogen concentration and temporal changes in each output in this example. The data processing procedure of this embodiment will be explained with reference to FIGS. 8 and 9. The output of the pulse generator TPG is sent to the storage devices M21 to M by the timing pulse distributors TP1 to TP4.
24 are sequentially input. Storage devices M21 to M24
stores the value of the concentration signal 14 while this timing pulse is being input. The pulse width ΔT ₁ of the timing pulse is a sufficient time to rewrite the contents of the storage devices M21 to M24. Similarly, the subtracter 20 is used for the storage devices M31 to M34.
The outputs of a to 20d are stored in synchronization with the respective timing pulses. First, at time _T0 , the concentration signal 14 is stored in the storage device M by the output of the timing pulse distributor TP4.
21. Let the concentration output at this time be C ₀ . Next, at time T ₁ after time ΔT ₀ , the concentration signal 14 is stored in the storage device M22 by the output of the timing pulse distributor TP1. Let the concentration output at this time be _C1 . In this state, the output of the subtracter 20a is determined by the outputs of the storage devices M21 and M22, so that the output of the subtracter 20a=C ₁ −C ₀ and is stored in the storage device M31 according to the output of the timing pulse distributor TP1. In this case, other storage devices M21 to M24, M32 to M3
The memory contents of 4 are not changed. The output of the storage device M31 is sent to the comparators 21a and 25.
a and is compared with the concentration output change alarm set value ΔC _H and trip set value ΔC _HH . The output of the comparator 21a is “1” when the input value ≧ΔC _H. The output of the comparator 25a is “1” when the input value ≧ ΔC _HH . The output of the comparator 25a is “1” when the input value ≧ ΔC _{HH .} For example, C ₁ −C ₀ >ΔC _H , C ₁ −C ₀ >ΔC _HH
If so, the output of the comparator 21a will be "1" and the output of the comparator 25a will be "1". Such signal processing is similarly performed for T ₂ , T ₃ , T ₄ . . . Tn. Timing pulses to each storage device are input every 4 pulses from the pulse generator, so for example,
The value stored at time T ₁ is not changed until time T ₅ , and is changed to a new value at time T ₅ . The outputs of the comparators 21a to 21d are determined by a 3/4 logic circuit 22a, and an alarm output signal 16 is output. The outputs of comparators 25a to 25d are 3/4
It is determined by the logic circuit 22b and a trip output signal 17 is output. In the example of FIG. 9, the alarm output signal 16 is output at time _T7 when the outputs of 21b to 21d become "1", and the trip output signal 1
7 is output at time _T10 when the outputs of 25a to 25c become "1". In the embodiments shown in FIGS. 8 and 9, the time interval Δt for data acquisition and the calculation time interval ΔT ₀ are the same, but as in the embodiments shown in FIGS. , data acquisition time interval Δt
and the calculation time interval ΔT ₀ may be set separately. 10 and 11 are modifications of the signal processing device shown in FIG. 8. Figure 10 shows alarm output signal 1
This is an example in which the discriminating circuit for the 6 and trip output signals is a 2/3 logic circuit 26a26b, and along with this, the memory devices M21 to M23, M31 to M3
4. Subtractors 20a to 20c, comparators 21a to 21
The number of circuits 25a to 25c is three each. The basic operation is the same as that shown in FIG. FIG. 11 is an example in which timers 27a to 27h are used in place of the pulse generator TPG and timing pulse distributors TP1 to TP4 in FIG. 8. [Effects of the Invention] The present invention provides at least three time intervals ΔT ₀₁ , ΔT ₀₂ , ΔT ₀₃ , ΔT ₀₄ , . At least 3 with length ΔT
time intervals T ₁ −T ₀ , T ₂ −T ₁ , T ₃ −T ₂ , T ₄ −
The change in hydrogen concentration at T ₃ ,... is determined, and a majority vote is taken to determine whether there is a water leak. This eliminates the possibility of misjudgment caused by disturbances or electrical noise caused by sudden changes in plant operating conditions. The probability is lowered and the effects of noise etc. can be eliminated. Therefore, no false alarm output signal or trip output signal is issued, and the reliability of the device is greatly improved.

[Brief explanation of drawings]

Figure 1 shows an example of the overall configuration of a conventional water leak detection device, Figure 2 shows an example of the configuration of a conventional signal processing device, and Figure 3 shows a conventional change in hydrogen concentration over time and an alarm. A diagram showing an example of the relationship between the set value and the trip set value, FIG. 4 is a diagram showing the configuration of an embodiment of the signal processing device in the water leak detection device according to the present invention, and FIG. FIG. 6 is a diagram showing the relationship between changes in hydrogen concentration and temporal changes in each output; FIG. 7 is a diagram showing a modification of the embodiment in FIG. 4; FIG. 8 is a diagram showing the configuration of another embodiment of the signal processing device of the present invention, FIG. 9 is a diagram showing the relationship between changes in hydrogen concentration and temporal changes in each output, and FIG.
The figure and FIG. 11 are diagrams showing a modification of the embodiment of FIG. 8. 14...Hydrogen concentration signal, 15...Signal processing device, 16...Alarm output signal, 17...Trip output signal, 20...Subtractor, 21, 25...Comparator, M...Storage device, 23... …3/4 logic circuit,
24...2/3 logic circuit.

Claims (1)

[Scope of Claims] 1. In a water leakage detection device that detects water leakage from a water region to a liquid metal region of a device in which a liquid metal region and a water region are located close to each other based on a change in hydrogen concentration, a predetermined interval Δt is provided. means for acquiring hydrogen concentration data for each time point; and both ends of at least three time intervals ΔT ₀₁ , ΔT ₀₂ , ΔT ₀₃ , ΔT ₀₄ , ... having different lengths longer than the predetermined interval Δt and having the same reference time point. From the hydrogen concentration data M0, M1, M2, M3, M4, ..., the respective time intervals ΔT ₀₁ , ΔT ₀₂ , ΔT ₀₃ ,
Changes in hydrogen concentration of ΔT ₀₄ ,… ΔC ₀₁ , ΔC ₀₂ , ΔC ₀₃ ,
means for determining ΔC ₀₄ , ...; and the plurality of hydrogen concentration changes ΔC ₀₁ , ΔC ₀₂ ,
means for comparing ΔC ₀₃ , ΔC ₀₄ , ... with predetermined upper limit values ΔC _H , ΔC _HH ; means for determining the presence or absence of water leakage by taking a majority vote on the results of the comparison; and changing the reference point in the time interval from To to Tn. A water leak detection device characterized by comprising: means for changing and repeating the above procedure. 2. In a water leak detection device that detects water leakage from the water region to the liquid metal region of a device in which a liquid metal region and a water region are located in close proximity, the hydrogen concentration at each time point of a predetermined interval Δt is detected. means for capturing data; at least three time intervals T ₁ -T ₀ , T ₂ -T ₁ , T ₃ - having the same length ΔT greater than or equal to the predetermined interval Δt;
From the hydrogen concentration data at both ends of T ₂ , T ₄ −T ₃ , ..., the change in hydrogen concentration at each time interval ΔC ₀₁ ,
Means for determining ΔC ₁₂ , ΔC ₂₃ , ΔC ₃₄ , ..., and the plurality of changes in hydrogen concentration ΔC ₀₁ , ΔC ₁₂ ,
means for comparing ΔC ₂₃ , ΔC ₃₄ , ... with predetermined upper limit values ΔC _H , ΔC _HH ; means for determining the presence or absence of water leakage by taking a majority vote on the results of the comparison; and determining the reference time of the time interval from T ₀ to T _o and means for repeating the above procedure.