JP6649295B2 - Equipment atmosphere monitoring device, equipment atmosphere monitoring method, and component set of equipment atmosphere monitoring device - Google Patents

Description

  An embodiment of the present invention relates to a facility atmosphere monitoring technique for monitoring the atmosphere inside a facility in a nuclear power plant.

  When the temperature of a reactor core becomes high due to a loss of coolant due to a severe accident at a nuclear power plant, hydrogen gas is generated from the reactor by a zirconium-water reaction. For this reason, a containment vessel atmosphere monitor (CAMS: Containment Atmospheric Monitoring System) for detecting the concentration of hydrogen gas contained in the sampling gas extracted from the containment vessel of the nuclear reactor with a detector is provided. Here, the detector cannot perform accurate detection if the sampling gas contains a large amount of water. Therefore, the sampling gas is passed through a dehumidifier to dehumidify, and thereafter, the concentration of hydrogen gas is detected by a detector.

JP-A-2000-2784 JP 2013-19751 A

  However, when a severe accident occurs in a nuclear power plant, the temperature inside a building provided with a dehumidifier (cooling device) or the like may increase. Here, if the temperature around the dehumidifier rises to a temperature exceeding the cooling capacity of the dehumidifier, the dew point temperature of the sampling gas (atmosphere) cannot be controlled to be constant. There is a problem that accurate detection becomes impossible.

  The embodiment of the present invention has been made in consideration of such circumstances, and even when the temperature around the cooling device increases during a severe accident, it is possible to control the temperature of the atmosphere extracted by the sampling pipe to be constant. It is an object of the present invention to provide a technology for monitoring the atmosphere in equipment that can be used.

  The equipment atmosphere monitoring device according to the embodiment of the present invention is provided in the sampling pipe for extracting a part of the atmosphere in the equipment, a dehumidifying unit provided in the sampling pipe to dehumidify the atmosphere, and provided in the dehumidifying unit. A cooling device for lowering the temperature of the atmosphere, an ambient temperature detector for detecting an ambient temperature of the cooling device, and controlling the cooling device in a first mode when the ambient temperature is lower than a specific temperature; A temperature controller configured to control the cooling device in a second mode different from the first mode when the temperature is equal to or higher than the specific temperature; and a predetermined gas provided downstream of the dehumidifier and included in the atmosphere. And a gas detector for detecting

  According to the embodiment of the present invention, there is provided a facility atmosphere monitoring technology capable of controlling the temperature of the atmosphere extracted by the sampling pipe to be constant even when the temperature around the cooling device increases in a severe accident.

FIG. 1 is a configuration diagram illustrating a facility atmosphere monitoring device according to a first embodiment. 4 is a flowchart illustrating a method for monitoring the atmosphere in the facility according to the first embodiment. 9 is a flowchart showing each process executed by the first and second temperature setting units. 9 is a flowchart illustrating a set temperature switching process executed by a temperature switching unit. The block diagram which shows the atmosphere monitoring apparatus in 2nd Embodiment. 9 is a flowchart illustrating a method for monitoring the atmosphere in a facility according to a second embodiment.

(1st Embodiment)
Hereinafter, the present embodiment will be described with reference to the accompanying drawings. First, the equipment atmosphere monitoring device according to the first embodiment will be described with reference to FIGS. The reference numeral 1 in FIG. 1 denotes a facility atmosphere monitoring device (CAMS) provided in a nuclear power plant. The facility atmosphere monitoring device 1 monitors the concentration of hydrogen gas and the concentration of oxygen gas contained in the sampling gas G extracted from the inside of the reactor containment vessel 2.

  The reactor containment vessel 2 is a facility for storing a reactor pressure vessel (not shown) containing a core in which nuclear fuel is arranged. The containment vessel 2 is a strong structure formed of stainless steel or concrete, and serves as a pressure barrier in the event of a severe accident (SA) and a barrier against the emission of radioactive materials. Form.

  Further, a space in which various devices for driving the control rods are provided is secured inside the reactor containment vessel 2. Further, at the time of maintenance of the nuclear power plant, a worker can perform work inside the reactor containment vessel 2. In addition, a drain sump (not shown) for collecting and draining water leaking from various types of atomic piping is provided below the reactor containment vessel 2.

  Further, a suppression chamber (not shown) holding cooling water is connected to the reactor containment vessel 2. This suppression chamber is a facility for guiding the steam to the suppression chamber to cool and reduce the pressure when the cooling water inside the reactor pressure vessel decreases and the steam pressure increases during a severe accident. It is. Further, the suppression chamber may be provided integrally with the bottom of the containment vessel 2.

  Various safety measures are taken for nuclear power plants. For example, when the supply of cooling water to the reactor pressure vessel is stopped or when the cooling water is lost due to the breakage of the piping connected to the reactor pressure vessel, the water level inside the reactor pressure vessel drops, and the core Is exposed and cooling is insufficient. In such a case, the emergency stop of the reactor is automatically performed by the signal of the water level drop. Further, the core is flooded and cooled by injection of cooling water by an emergency core cooling system (ECCS: Emergency Core Cooling System) to prevent a core melting accident.

  However, with a very low probability, a situation can be assumed in which the emergency core cooling device does not operate and other water injection devices for the core cannot be used. For example, when the external power supply or the emergency power supply is lost due to a factor such as an earthquake disaster, the supply of the cooling water to the reactor pressure vessel may be stopped. In such a situation, the water level inside the reactor pressure vessel is lowered, so that the core is exposed and cooling is not performed. Then, it is conceivable that the temperature of the nuclear fuel rises due to the decay heat that continues to be generated even after the reactor shuts down, leading to melting of the core.

  Here, when a metal alloy such as zirconium that covers the nuclear fuel is melted, this metal alloy reacts with surrounding steam (water) to generate hydrogen gas. Then, the hydrogen gas leaks outside through a gap such as a crack generated in the reactor pressure vessel, and accumulates inside the containment vessel 2. If the concentration of the hydrogen gas and the concentration of the oxygen gas contained in the atmosphere inside the containment vessel 2 exceed a predetermined concentration, there is a risk that a hydrogen explosion may occur. Therefore, the atmosphere inside the reactor containment vessel 2 is monitored using the equipment atmosphere monitoring device 1. Note that the equipment atmosphere monitoring device 1 monitors not only at the time of a severe accident but also at normal times. By using the in-facility atmosphere monitoring device 1, it is possible to detect in advance whether a hydrogen explosion or the like occurs.

  As shown in FIG. 1, the in-facility atmosphere monitoring device 1 includes a sampling pipe 3 for extracting a part of the atmosphere inside the reactor containment vessel 2 as a sampling gas G. The suction side end of the sampling pipe 3 is connected to the containment vessel 2, and extends from the inside of the containment vessel 2 to the outside. In the vicinity of the containment vessel 2, a sampling rack (not shown) in which various devices including the sampling pipe 3 are arranged is provided. The sampling rack is provided indoors such as a reactor building (not shown).

  The sampling pipe 3 has an air-cooling type cooling unit 4 for cooling the sampling gas G, an air-cooling type dehumidifying unit 5 for dehumidifying the sampling gas G, and sucks the sampling gas G from the inside of the containment vessel 2. An intake pump 6, a gas pressure reducing valve 7 for constantly reducing the pressure of the sampling gas G, an oxygen gas detector 8 for detecting the oxygen gas concentration, a hydrogen gas detector 9 for detecting the hydrogen gas concentration, and a sampling gas G A flow rate detector 10 for controlling and detecting the flow rate of the sample gas at a constant level, and an exhaust pump 11 for exhausting the sampling gas G into the reactor containment vessel 2. In addition, a drain storage unit 12 that stores the drain water W removed by the cooling unit 4 and the dehumidifying unit 5 is provided near the sampling pipe 3.

  The in-facility atmosphere monitoring device 1 according to the present embodiment includes an oxygen measuring device 13 that measures an oxygen concentration based on an oxygen detection signal C1 output from an oxygen gas detector 8, and a hydrogen detection device output from a hydrogen gas detector 9. A hydrogen measuring device 14 for measuring the hydrogen concentration based on the signal C2, an arithmetic control unit 15 for obtaining an oxygen concentration signal C3 output from the oximeter 13 and a hydrogen concentration signal C4 output from the hydrogen measuring device 14, Is provided. Here, the oxygen concentration signal C3 indicates a detected value of the oxygen concentration contained in the sampling gas G, and the hydrogen concentration signal C4 indicates a detected value of the hydrogen concentration contained in the sampling gas G.

  It should be noted that signals other than the oxygen concentration signal C3 and the hydrogen concentration signal C4 are also input to the arithmetic control unit 15. Then, the arithmetic and control unit 15 controls various devices based on these signals. For example, the arithmetic and control unit 15 controls the intake pump 6 and the exhaust pump 11 to allow the sampling gas G to flow through the sampling pipe 3. Further, the arithmetic and control unit 15 transmits various information on the sampling gas G such as the oxygen concentration and the hydrogen concentration to a central control room (not shown) of the nuclear power plant.

  Further, an exhaust-side end of the sampling pipe 3 is connected to the reactor containment vessel 2. Then, the sampling gas G whose concentration of the hydrogen gas and the oxygen gas has been detected returns to the inside of the containment vessel 2.

  In this embodiment, a magnetic wind type oxygen gas detector 8 and a heat conduction type hydrogen gas detector 9 are used. If the sampling gas G has a high moisture content, the magnetic wind type oxygen gas detector 8 and the heat conduction type hydrogen gas detector 9 may not be able to perform accurate detection. Therefore, the sampling gas G is dehumidified by using the cooling unit 4 and the dehumidifying unit 5, and each gas is detected by the oxygen gas detector 8 and the hydrogen gas detector 9 provided downstream of the dehumidifying unit 5. Like that.

  Here, when performing dehumidification, first, the sampling gas G is passed through the cooling unit 4. In the cooling unit 4, the temperature of the sampling gas G is reduced to the ambient temperature (room temperature) of the cooling unit 4. Thereafter, dehumidification is performed by passing the sampling gas G through a dehumidification unit 5 provided downstream of the cooling unit 4. In normal times, the dehumidifying unit 5 lowers the temperature of the sampling gas G to a preset first temperature (for example, 5 ° C. or lower). The amount of moisture (humidity) contained in the sampling gas G lowered to the first temperature is almost 0%. The oxygen gas and the hydrogen gas can be accurately detected by detecting the components contained in the dehumidified sampling gas G by the oxygen gas detector 8 and the hydrogen gas detector 9.

  Further, piping other than the sampling piping 3 is provided in the sampling rack. For example, the first drain pipe 16 that guides the drain water W generated in the cooling unit 4 and the dehumidifying unit 5 to the drain storage unit 12 and the drain water W in the drain storage unit 12 are connected to a drain sump or a suppression chamber inside the reactor containment vessel 2. And a connection pipe 18 connecting the sampling pipe 3 and the first drain pipe 16 are provided.

  In addition, valves 19 to 23 are provided in the sampling pipe 3 and the drain pipes 16, 17, and 18 to control the flow path of the sampling gas G or the drain water W by opening and closing operations. For example, in the sampling pipe 3, a first valve 19 is provided upstream of the intake pump 6, and a second valve 20 is provided downstream of the exhaust pump 11. Further, a third valve 21 is provided in the connection pipe 18, a fourth valve 22 is provided in the first drain pipe 16, and a fifth valve 23 is provided in the second drain pipe 17. Here, at normal times, the first valve 19, the second valve 20, and the fourth valve 22 are opened, and the third valve 21 and the fifth valve 23 are closed.

  Further, a liquid level detector 24 for detecting the liquid level of the drain water W stored in the drain storage unit 12 is provided. The liquid level signal C5 indicating the liquid level detected by the liquid level detector 24 is input to the arithmetic and control unit 15. In addition, the liquid level height of the drain water W in the drain storage unit 12 changes with time. Then, the arithmetic and control unit 15 acquires the amount of change in the drain water W based on the liquid level signal C5. Further, before the storage amount of the drain water W increases and exceeds the detectable range of the liquid level detector 24, the arithmetic and control unit 15 outputs the control signal C6 to the fifth valve 23. Then, the fifth valve 23 is opened, and the drain water W is discharged to the suppression chamber at the bottom of the reactor containment vessel 2.

  When draining the drain water W, the fourth valve 22 is closed and the third valve 21 is opened. By opening the third valve 21, the drain water W can be discharged using the pressure of the sampling gas G pressurized by the exhaust pump 11.

  The sampling gas G detected by the oxygen gas detector 8 and the hydrogen gas detector 9 is a gas from which moisture has been removed in the cooling unit 4 and the dehumidifying unit 5. A higher value concentration is detected as compared to the oxygen concentration and the hydrogen concentration. This value increases as the amount of water removed from the sampling gas G increases. Therefore, the arithmetic and control unit 15 corrects the oxygen concentration and the hydrogen concentration detected by the oxygen gas detector 8 and the hydrogen gas detector 9.

  For example, the arithmetic and control unit 15 calculates the amount of water removed from the sampling gas G based on the liquid level signal C5 of the liquid level detector 24. Further, the arithmetic and control unit 15 calculates a moisture correction coefficient based on the water content. Then, the arithmetic control unit 15 corrects the oxygen concentration and the hydrogen concentration detected by the oxygen gas detector 8 and the hydrogen gas detector 9 using the moisture correction coefficient.

  When a severe accident occurs in a nuclear power plant, a sufficient amount of cooling water may not be obtained. Therefore, in this embodiment, an air-cooled cooling unit 4 and a dehumidifying unit 5 are used. Further, at least the dehumidifying section 5 only needs to be air-cooled, and the cooling section 4 provided upstream of the dehumidifying section 5 may be a water-cooled type. Further, the provision of the air-cooled cooling unit 4 allows the cooling unit 4 to lower the temperature of the sampling gas G to the ambient temperature even in a situation where sufficient cooling water cannot be secured in a severe accident or the like. Can be.

  Next, the dehumidifying section 5 of the present embodiment will be described in detail. The dehumidifying unit 5 includes a cooling device 25 that lowers the temperature of the sampling gas G, an ambient temperature detector 26 that detects an ambient temperature of the cooling device 25, and an outlet temperature of the sampling gas G at an outlet side of the dehumidifying unit 5. And an outlet temperature detector 27 for detecting. Note that the ambient temperature detector 26 and the outlet temperature detector 27 are temperature detectors composed of side temperature resistors.

  Further, the cooling device 25 includes a Peltier device 28 for transferring heat of the sampling gas G passing through the dehumidifying unit 5, a radiator 29 for releasing the heat transferred by using the Peltier device 28 to the surroundings, and a radiator 29. And a fan 30 provided in the device. The heat radiating section 29 includes a plurality of air-cooled fins (radiators). Further, the fan 30 is constantly rotating.

  In this way, the temperature of the sampling gas G flowing through the sampling pipe 3 by radiating heat around the cooling device 25 can be reduced. The use of the Peltier element 28 simplifies the configuration of the cooling device 25 and makes it harder to break down in a severe accident. Further, by radiating heat using the air-cooled fins and the fan 30, even in a situation where sufficient cooling water cannot be secured in a severe accident or the like, the temperature of the atmosphere can be reduced using the cooling device 25. it can.

  Further, inside the dehumidifying section 5, the sampling pipe 3 has a spiral shape, and the contact area with the Peltier element 28 is increased. Therefore, efficient heat exchange can be performed. Further, the outlet temperature detector 27 is in contact with the sampling pipe 3 and obtains the temperature of the sampling pipe 3 to measure the temperature of the sampling gas G.

  The above-described ambient temperature detector 26 detects the temperature (ambient temperature) of the air near the heat radiating section 29 and outputs an ambient temperature signal C7 indicating the detected temperature. The outlet temperature detector 27 detects the temperature (outlet temperature) of the sampling gas G on the outlet side of the dehumidifying section 5 and outputs an outlet temperature signal C8 indicating the detected temperature.

  The Peltier element 28 is a plate-shaped semiconductor element using the Peltier effect that when a direct current is applied to a junction between two kinds of metals, heat moves from one metal to the other. In this Peltier element 28, when a direct current is passed, one surface absorbs heat (cools) and the other surface dissipates heat. The heat radiating portion 29 is provided on the surface from which heat is radiated. By cooling the sampling gas G using the Peltier device 28, even in a place where the radiation dose is high in a nuclear power plant, the cooling device 25 operates without failure, and sufficient cooling capacity can be obtained in a severe accident.

  Further, the Peltier device 28 can generate a temperature difference of up to approximately 40 ° C. between one surface and the other surface. For example, when the ambient temperature of the heat radiating section 29 is 30 ° C. in normal times, the temperature of the sampling gas G can be reduced to 5 ° C. or less. Then, the temperature of 5 ° C. can be kept constant for a long time. However, when the temperature of the sampling gas G is reduced by the Peltier device 28, the lower limit of the target temperature for cooling depends on the temperature of the air around the heat radiating unit 29.

  However, at the time of a severe accident, it is assumed that the temperature inside the reactor building will rise to 66 ° C. If the ambient temperature of the heat radiating section 29 is 60 ° C., the temperature of the sampling gas G can be reduced to 20 ° C. by using the Peltier element 28, but cannot be reduced to 5 ° C. described above. Therefore, the temperature of the sampling gas G fluctuates with the fluctuation of the ambient temperature around 20 ° C., and cannot be maintained at a constant temperature.

  Here, the oxygen gas detector 8 and the hydrogen gas detector 9 detect the gas concentration on the assumption that the temperature of the sampling gas G is constant. Therefore, when the temperature of the sampling gas G is not constant, there is a possibility that the gas concentration may not be accurately detected using the oxygen gas detector 8 and the hydrogen gas detector 9. Therefore, in order to keep the temperature of the sampling gas G constant for a long time, the target temperature for cooling the sampling gas G is switched to a temperature different from the normal temperature.

  In the present embodiment, during a severe accident, the target temperature for cooling the sampling gas G is set to be higher than normal. For example, when the temperature of the sampling gas G is lowered to 5 ° C. in normal times, the temperature of the sampling gas G is lowered to 30 ° C. in a severe accident. Even if the temperature of the air around the heat radiating section 29 is 66 ° C., the Peltier device 28 can reduce the temperature of the sampling gas G to 30 ° C. and keep this 30 ° C. constant for a long time. Can be kept.

  For example, the atmosphere inside the reactor containment vessel 2 in normal times is room temperature (about 25 ° C.). At this time, the ambient temperature of the cooling unit 4 and the dehumidifying unit 5 is also room temperature. However, at the time of a severe accident, the atmosphere inside the containment vessel 2 may reach about 200 ° C. At this time, it is assumed that the ambient temperature of the cooling section 4 and the dehumidifying section 5 is about 66 ° C. Then, the high-temperature sampling gas G of about 200 ° C. is cooled to about 70 ° C. in the cooling unit 4. Further, the sampling gas G cooled by the cooling unit 4 is lowered to 30 ° C. by using the Peltier device 28 of the dehumidifying unit 5.

  Further, the in-facility atmosphere monitoring device 1 is provided with a temperature control unit 31 for controlling the Peltier element 28. The temperature control unit 31 is started under the control of the arithmetic control unit 15 described above. Further, electric circuits such as the temperature control unit 31 and the arithmetic control unit 15 are provided in a safe facility other than the reactor building where the sampling rack is located. Even if a severe accident occurs, the temperature and radiation dose of the facility provided with the temperature control unit 31 and the arithmetic control unit 15 are not different from those in normal times. The temperature controller 31 and the arithmetic controller 15 are connected to various devices of the sampling rack via signal lines.

  Note that the temperature control unit 31 performs ON / OFF control of the Peltier device 28. For example, when the outlet temperature of the dehumidifying unit 5 is lower than a predetermined set temperature, the temperature control unit 31 turns off the Peltier element 28 (a state in which current does not flow through the Peltier element 28), and the outlet temperature of the dehumidifying unit 5 is set. When the temperature is equal to or higher than the temperature, the Peltier element 28 is turned on (a state in which a current flows through the Peltier element 28) and cooled.

  The temperature control unit 31 is connected to the temperature switching unit 32 that switches the target temperature for cooling the sampling gas G, the first temperature setting unit 33 that is normally connected to the Peltier device 28, and is connected to the Peltier device 28 in a severe accident. A second temperature setting section is provided, and a changeover switch 35 for connecting the Peltier element to either the first temperature setting section 33 or the second temperature setting section so as to be switchable. The changeover switch 35 is controlled by the temperature switching unit 32.

  The ambient temperature signal C7 output from the ambient temperature detector 26 is input to the temperature switching unit 32. Further, an outlet temperature signal C8 output from the outlet temperature detector 27 is input to the first temperature setting unit 33 and the second temperature setting unit 34.

  In the temperature switching unit 32, a specific temperature for which the ambient temperature is to be determined is set in advance. For example, 40 ° C. is set as the specific temperature. In the first temperature setting unit 33, the first temperature is set in advance as a target temperature (set temperature) for cooling the sampling gas G in normal times. For example, 5 ° C. is set as the first temperature. The second temperature is set in advance in the second temperature setting unit 34 as a target temperature (set temperature) for cooling the sampling gas G at the time of a severe accident. For example, 30 ° C. is set as the second temperature.

  The first temperature setting unit 33 turns off the Peltier device 28 when the outlet temperature of the dehumidifying unit 5 is lower than the first temperature, and turns off the Peltier device 28 when the outlet temperature of the dehumidifying unit 5 is equal to or higher than the first temperature. Turn on. The second temperature setting unit 34 turns off the Peltier device 28 when the outlet temperature of the dehumidifying unit 5 is lower than the second temperature, and turns off the Peltier device 28 when the outlet temperature of the dehumidifying unit 5 is equal to or higher than the second temperature. Turn on.

  Note that the temperature switching unit 32 connects the first temperature setting unit 33 to the Peltier element 28 by controlling the switch 35 when the ambient temperature of the heat radiation unit 29 is lower than the specific temperature. Further, the temperature switching unit 32 connects the second temperature setting unit 34 to the Peltier device 28 by controlling the switch 35 when the ambient temperature of the heat radiation unit 29 is equal to or higher than the specific temperature. That is, when the ambient temperature of the heat radiating unit 29 is lower than the specific temperature, the temperature switching unit 32 sets the target temperature (set temperature) for cooling the sampling gas G to the first temperature, and the ambient temperature of the heat radiating unit 29 is specified. When the temperature is equal to or higher than the temperature, the target temperature (set temperature) for cooling the sampling gas G is set to the second temperature higher than the first temperature.

  With this configuration, it is possible to switch the target set temperature for controlling the temperature of the atmosphere to be constant according to the cooling capacity of the cooling device. Further, by using the temperature switching unit 32, the first temperature setting unit 33, and the second temperature setting unit 34, the circuit configuration for switching the target temperature for cooling the sampling gas G can be simplified.

  Note that the arithmetic control unit 15, the temperature switching unit 32, the first temperature setting unit 33, and the second temperature setting unit 34 have hardware resources such as a processor and a memory. Is realized by a computer realized by using hardware resources. Further, the method for monitoring the atmosphere in the facility and other processes according to the present embodiment are realized by causing a computer to execute a program.

  Next, a method for monitoring the atmosphere in a facility according to the first embodiment will be described with reference to the flowchart in FIG. In the description of each step of the flowchart, for example, a portion described as “Step S11” is abbreviated as “S11”.

  First, the arithmetic and control unit 15 drives the intake pump 6 and the exhaust pump 11 to extract a part of the atmosphere inside the reactor containment vessel 2 as the sampling gas G, and distribute the sampling gas G to the sampling pipe 3. (S11: extraction step). Next, the sampling gas G derived from the containment vessel 2 is cooled by passing through the cooling unit 4 (S12). In the cooling unit 4, the temperature of the sampling gas G is reduced to a temperature around the cooling unit 4.

  Next, the sampling gas G that has passed through the cooling unit 4 is dehumidified by passing through the dehumidification unit 5 (S13: dehumidification step). In the dehumidifying section 5, the temperature of the sampling gas G is reduced to the set temperature by using the cooling device 25 (Peltier element 28). Next, the temperature control unit 31 executes a set temperature switching process (S14: temperature control step).

  Next, the oxygen gas and the hydrogen gas contained in the sampling gas G are detected using the oxygen gas detector 8 and the hydrogen gas detector 9 provided downstream of the dehumidifying section 5. Then, based on these detections, the oxygen meter 13 and the hydrogen meter 14 measure the oxygen concentration and the hydrogen concentration (S15: detection step), and output these detected values (measured values) to the arithmetic and control unit 15. Then, the method for monitoring the atmosphere in the equipment is completed.

  Next, the first temperature setting process (the control in the first mode) executed by the first temperature setting unit 33 will be described with reference to the flowchart in FIG.

  First, the outlet temperature detector 27 detects the outlet temperature of the dehumidifying unit 5, and an outlet temperature signal C8 indicating the outlet temperature is input to the first temperature setting unit 33 (S21). Next, the first temperature setting unit 33 determines whether the outlet temperature is equal to or higher than the first temperature (for example, 5 ° C.) (S22).

  Here, if the outlet temperature is lower than the first temperature, the Peltier element 28 is turned off (S23), and the first temperature setting process ends. On the other hand, if the outlet temperature is equal to or higher than the first temperature, the Peltier element 28 is turned on (S24: cooling step), and the first temperature setting process ends.

  The first temperature setting unit 33 executes the first temperature setting process, so that the temperature of the sampling gas G is maintained at the first temperature. The first temperature setting process is performed by the changeover switch 35 regardless of whether the first temperature setting unit 33 is connected to the Peltier device 28 or not.

  Next, the second temperature setting process (the control in the second mode) executed by the second temperature setting unit 34 will be described with reference to the flowchart in FIG.

  First, the outlet temperature detector 27 detects the outlet temperature of the dehumidifying unit 5, and an outlet temperature signal C8 indicating the outlet temperature is input to the second temperature setting unit 34 (S25). Next, the second temperature setting unit 34 determines whether or not the outlet temperature is equal to or higher than a second temperature (for example, 30 ° C.) (S26).

  Here, if the outlet temperature is lower than the second temperature, the Peltier element 28 is turned off (S27), and the second temperature setting process ends. On the other hand, if the outlet temperature is equal to or higher than the second temperature, the Peltier element 28 is turned on (S28: cooling step), and the second temperature setting process ends.

  The second temperature setting unit 34 executes the second temperature setting process, so that the temperature of the sampling gas G is maintained at the second temperature. The second temperature setting process is executed by the changeover switch 35 regardless of whether the second temperature setting unit 34 is connected to the Peltier device 28 or not.

  Next, the set temperature switching process executed by the temperature switching unit 32 will be described with reference to the flowchart of FIG.

  First, the ambient temperature detector 26 detects the ambient temperature of the heat radiating section 29, and an ambient temperature signal C7 indicating the ambient temperature is input to the temperature switching section 32 (S31: ambient temperature detecting step). Next, the temperature switching unit 32 determines whether the ambient temperature is equal to or higher than a specific temperature (for example, 40 ° C.) (S32).

  Here, if the ambient temperature is lower than the specific temperature, the Peltier device 28 is connected to the first temperature setting unit 33 using the changeover switch 35 (S23), and the set temperature switching process ends. On the other hand, if the ambient temperature is equal to or higher than the specific temperature, the Peltier device 28 is connected to the second temperature setting unit 34 using the changeover switch 35 (S24), and the set temperature switching process ends.

(2nd Embodiment)
Next, a facility atmosphere monitoring device 1A according to a second embodiment will be described with reference to FIGS. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  As described above, the sampling gas G is cooled to the first temperature (for example, 5 ° C.) in normal times, and the sampling gas G is cooled to the second temperature (for example, 30 ° C.) in a severe accident. Here, the amount of moisture (humidity) contained in the sampling gas G lowered to the first temperature becomes almost 0%, but a small amount of water remains in the sampling gas G lowered to the second temperature. If it is attempted to detect each gas contained in the sampling gas G in a state where the moisture remains, a slight error occurs in the detected value. Therefore, in the second embodiment, when the sampling gas G is cooled to the second temperature at the time of a severe accident, the detection value of each gas included in the sampling gas G is corrected.

  As shown in FIG. 5, the in-facility atmosphere monitoring device 1A according to the second embodiment includes, in addition to the various devices according to the first embodiment, a moisture calculating unit 36 that calculates the amount of moisture contained in the sampling gas G. And a concentration corrector 37 for correcting the detected values of the concentrations of oxygen gas and hydrogen gas.

  In the moisture calculating section 36, the temperature switching section 32 and the flow rate detector 10 are connected via a signal line. In addition, the temperature switching unit 32 is a signal indicating the state of the changeover switch 35, and outputs a state signal C9 indicating whether the Peltier element 28 is connected to the first temperature setting unit 33 or the second temperature setting unit 34. Output. This state signal C9 is input to the moisture calculating section 36.

  Here, the first temperature (for example, 5 ° C.) and the second temperature (for example, 30 ° C.) of the first temperature setting unit 33 and the second temperature setting unit 34 are set in advance. It can be assumed that these set temperatures are the temperatures of the sampling gas G to be detected by the oxygen gas detector 8 and the hydrogen gas detector 9. That is, the moisture calculating unit 36 can obtain the temperature of the sampling gas G based on the state signal C9.

  Further, the flow detector 10 outputs a flow signal C10 indicating the flow rate of the sampling gas G. This flow signal C10 is input to the moisture calculating section 36. Since the pressure of the sampling gas G is kept constant by the gas pressure reducing valve 7, the volume can be calculated from the flow rate of the sampling gas G. That is, the moisture calculating unit 36 can acquire the volume of the sampling gas G based on the flow rate signal C10.

  Then, at the time of a severe accident, the Peltier element 28 is connected to the second temperature setting unit 34, so that the temperature of the sampling gas G is maintained at the second temperature. Then, the moisture calculating unit 36 can calculate the amount of moisture (water vapor concentration) contained in the sampling gas G based on the second temperature and the flow rate.

  Even if the temperature of the sampling gas G cooled by the Peltier element 28 rises before reaching the oxygen gas detector 8 and the hydrogen gas detector 9, the moisture content is invariable. Based on the second temperature set in the temperature setting unit 34, the amount of moisture can be obtained.

  When the Peltier element 28 is connected to the first temperature setting unit 33 in normal times, the moisture content (water vapor concentration) contained in the sampling gas G is almost 0%, and is known, so the moisture calculation is performed. There is no need for the unit 36 to calculate the moisture content.

  Further, the moisture calculating section 36 is connected to the concentration correcting section 37 via a signal line. The moisture calculating section 36 inputs a water vapor concentration signal C11 indicating the calculated water vapor concentration (moisture content) to the concentration correcting section 37. Then, the concentration corrector 37 corrects the oxygen concentration signal C3 obtained from the oxygen meter 13 and the hydrogen concentration signal C4 obtained from the hydrogen meter 14 based on the water vapor concentration obtained from the concentration corrector 37. Further, the concentration corrector 37 outputs the corrected oxygen concentration signal C3 and hydrogen concentration signal C4 to the arithmetic and control unit 15.

  In this way, even if the sampling gas G cannot be completely dehumidified in the dehumidifying section 5 during a severe accident, moisture remains and an error occurs in the detection values of the oxygen gas detector 8 and the hydrogen gas detector 9. The correct detection value can be obtained by correcting the detection value based on the moisture content calculated by the humidity calculation unit 36. That is, the detection accuracy of the oxygen gas concentration and the hydrogen gas concentration can be improved.

Next, an example of the method for calculating the amount of moisture will be described below.
The saturated vapor pressure (hPa) can be obtained by the following equation from the equation of tentens.
E (t) = 6.11 × 10 ＾ (7.5t ÷ (t + 237.3))
t: Gas temperature Inside the dehumidifying section 5, the temperature of the sampling gas G is equal to the cooling temperature. For example, if t = 30 ° C.,
E = 42.4 (hPa)
Becomes

  Further, at the outlet side of the dehumidifying section 5, the sampling gas G is cooled to remove water, and is cooled to the dew point temperature. Therefore, when the temperature of the sampling gas G is equal to the cooling temperature, the relative humidity can be considered to be 100%.

Also,
Absolute humidity (g / m ³ ) = 217 (constant) × (E (t) ÷ (t + 273.15)) × (relative humidity ÷ 100)
Because
Absolute humidity (g / m ³ ) = 217 × (42.4 ÷ (30 + 273.15)) × 1
Becomes
Absolute humidity (g / m ³ ) = 30.4 (g / m ³ )
Becomes

In addition, the water vapor volume (L / m ³ ) is a standard volume of 22.4 L with respect to a mass of 18 g per 1 mol of water.
Water vapor volume (L / m ³ ) = absolute humidity (g / m ³ ) × (22.4 ÷ 18) × ((273.15 + t) ÷ 273.15)
Because
Water vapor volume (L / m ³ ) = 30.4 × (22.4 ÷ 18) × ((273.15 + 30) ÷ 273.15)
Becomes
Water vapor volume (L / m ³ ) = 42.0 (L / m ³ )
Becomes

Further, from 1 m ³ = 1000 L, the water vapor concentration (vol%) in 1 L is:
Water vapor concentration (vol%) = water vapor volume (L / m ³ ) ÷ 1000 × 100
Becomes
Water vapor concentration (vol%) = 4.2 (vol%)
Becomes

  As described above, in the second embodiment, when the Peltier element 28 is connected to the second temperature setting unit 34 at the time of a severe accident, the moisture calculating unit 36 calculates the water vapor concentration (moisture amount). Further, the concentration corrector 37 corrects the detected value (measured value) of the concentration of oxygen gas and hydrogen gas based on the calculated water vapor concentration (moisture content). Then, the density correction unit 37 outputs the density signals C3 and C4 indicating the corrected detection values.

  When the Peltier element 28 is connected to the first temperature setting unit 33, the concentration correction unit 37 corrects each concentration signal C3 without correcting the detected value (measured value) of the concentration of oxygen gas and hydrogen gas. C4 is output. When the Peltier element 28 is connected to the first temperature setting unit 33, the moisture calculating unit 36 may output a water vapor concentration signal C11 indicating that the water vapor concentration is 0%. The density correction unit 37 may execute the same process regardless of whether the Peltier device 28 is connected to the first temperature setting unit 33 or the second temperature setting unit 34.

  Next, a method for monitoring the atmosphere in a facility according to the second embodiment will be described with reference to the flowchart in FIG. Note that, in the facility atmosphere monitoring method of the second embodiment, steps S11 to S15 are the same as the above-described facility atmosphere monitoring method of the first embodiment.

  In the second embodiment, the following steps are performed after S15. First, the moisture calculating unit 36 determines whether or not the Peltier device 28 is connected to the second temperature setting unit 34 based on the state signal C9 acquired from the temperature switching unit 32 (S16).

  Here, when the Peltier device 28 is not connected to the second temperature setting unit 34, that is, when the Peltier device 28 is connected to the first temperature setting unit 33, the moisture calculating unit 36 Does not calculate the amount of moisture (water vapor concentration) contained in. The concentration correction unit 37 outputs the concentration signals C3 and C4 to the arithmetic and control unit 15 without correcting the detected values (measured values) of the concentrations of the oxygen gas and the hydrogen gas, and terminates the facility atmosphere monitoring method. .

  On the other hand, when the Peltier device 28 is connected to the second temperature setting unit 34, the moisture calculating unit 36 detects the flow rate of the sampling gas G based on the flow rate signal C10 acquired from the flow rate detector 10 ( S17). Next, the moisture calculating section 36 calculates the amount of moisture (water vapor concentration) contained in the sampling gas G based on the flow rate of the sampling gas G and the second temperature set in the second temperature setting section 34 ( S18).

  Next, the moisture calculating section 36 inputs a water vapor concentration signal C11 indicating the calculated amount of moisture (water vapor concentration) to the concentration correcting section 37. Then, the concentration corrector 37 corrects the concentrations of the oxygen gas and the hydrogen gas based on the water vapor concentration signal C11 acquired from the moisture calculator 36 (S19). The concentration corrector 37 outputs the corrected oxygen concentration signal C3 and hydrogen concentration signal C4 to the arithmetic and control unit 15, and terminates the facility atmosphere monitoring method.

  Although the equipment atmosphere monitoring apparatus according to the present embodiment has been described based on the first to second embodiments, the configuration applied in any one of the embodiments may be applied to other embodiments. The configurations applied in the embodiments may be combined.

  It should be noted that, in the determination of the predetermined value (outlet temperature, ambient temperature) and the determination value (first temperature, second temperature, specific temperature) in the present embodiment, “whether or not the determination value is equal to or greater than” is determined. This determination may be a determination of “whether or not exceeds a determination value”, a determination of “whether or not is below a determination value”, or a determination of “whether or not is less than a determination value”.

  Note that, in the flowchart of the present embodiment, an example in which each step is executed in series is illustrated, but the order of each step is not necessarily fixed, and even if the order of some steps is switched. good. Also, some steps may be executed in parallel with other steps.

  Note that the cooling device 25, the ambient temperature detector 26, and the temperature control unit 31 may constitute a component set used in the equipment atmosphere monitoring device 1. In this way, when updating the existing facility atmosphere monitoring apparatus, the use of this component set can improve the facility atmosphere monitoring apparatus 1 to which the present invention is applied.

  In this embodiment, in order to monitor the atmosphere inside the reactor containment vessel 2, the in-facility atmosphere monitoring device 1 is used. Monitoring of the internal atmosphere may be performed. For example, the sampling pipe 3 may be connected to a position on the downstream side of the filter of the filter vent device, and the hydrogen gas or the oxygen gas of the sampling gas extracted through the sampling pipe 3 may be detected. This makes it possible to detect in advance whether or not a hydrogen explosion or the like occurs in the filter vent device.

  In the present embodiment, the set temperature that can be switched by the temperature control unit 31 is only two stages of the first temperature and the second temperature, but the set temperature of three or more stages is switched using the temperature control unit 31. It may be made to be possible.

  In the present embodiment, the oxygen gas or the hydrogen gas contained in the sampling gas G is detected by using the oxygen gas detector 8 or the hydrogen gas detector 9, but other gases may be detected. For example, a substance such as iodine contained in the sampling gas G may be detected by a gas detector.

  In the present embodiment, the cooling device 25 controlled by the temperature control unit 31 includes the Peltier element 28. However, the cooling device does not have to use the Peltier element 28. For example, the cooling device may include a compressor or a fan, and the operation mode of the compressor or the fan may be controlled by the temperature control unit 31. In this case, the life of the compressor or the fan can be extended.

  The nuclear power plant exemplified in the present embodiment may be a nuclear power plant having a boiling water reactor or a nuclear power plant having a pressurized water reactor.

  In the present embodiment, the cooling unit 4 and the dehumidifying unit 5 are air-cooled, but the cooling unit 4 and the dehumidifying unit 5 may be liquid-cooled (water-cooled). For example, in the dehumidifying section 5, the movement from the Peltier element 28 to the heat radiating section 29 may be performed by a liquid refrigerant.

  According to the embodiment described above, the cooling device is controlled in the first mode when the ambient temperature is lower than the specific temperature, and the cooling device is controlled in the second mode different from the first mode when the ambient temperature is higher than the specific temperature. By providing the temperature control unit for controlling, even if the temperature around the cooling device becomes high in a severe accident, the temperature of the atmosphere extracted by the sampling pipe can be controlled to be constant.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

  1 (1A): Atmosphere monitoring device in equipment, 2: Reactor containment vessel, 3: Sampling piping, 4: Cooling unit, 5: Dehumidifying unit, 6: Intake pump, 7: Gas pressure reducing valve, 8: Oxygen gas detector , 9: hydrogen gas detector, 10: flow rate detector, 11: exhaust pump, 12: drain storage unit, 13: oxygen measuring device, 14: hydrogen measuring device, 15: arithmetic control unit, 16: first drain pipe, 17 second drain pipe, 18 connection pipe, 19 first valve, 20 second valve, 21 third valve, 22 fourth valve, 23 fifth valve, 24 liquid level detector, 25 ... Cooling equipment, 26 ... Ambient temperature detector, 27 ... Outlet temperature detector, 28 ... Peltier element, 29 ... Heat radiation section, 30 ... Fan, 31 ... Temperature control section, 32 ... Temperature switching section, 33 ... First temperature setting Unit, 34: second temperature setting unit, 35: changeover switch, 36: wet Calculation unit, 37: concentration correction unit, C1: oxygen detection signal, C2: hydrogen detection signal, C3: oxygen concentration signal, C4: hydrogen concentration signal, C5: liquid level signal, C6: control signal, C7: ambient temperature signal, C8: outlet temperature signal, C9: state signal, C10: flow rate signal, C11: water vapor concentration signal, G: sampling gas, W: drain water.

Claims (12)

A sampling pipe for extracting a part of the atmosphere in the facility,
A dehumidifying unit provided in the sampling pipe to dehumidify the atmosphere;
A cooling device that is provided in the dehumidifying unit and reduces the temperature of the atmosphere;
An ambient temperature detector for detecting an ambient temperature of the cooling device;
A temperature at which the cooling device is controlled in the first mode when the ambient temperature is lower than the specific temperature, and the cooling device is controlled in a second mode different from the first mode when the ambient temperature is equal to or higher than the specific temperature. A control unit;
A gas detector provided downstream of the dehumidifying unit and detecting a predetermined gas contained in the atmosphere,
A facility atmosphere monitoring device comprising: An outlet temperature detector that detects an outlet temperature of the atmosphere on an outlet side of the dehumidifying unit,
A temperature setting unit that turns off the cooling device when the outlet temperature is lower than a predetermined set temperature, and turns on the cooling device when the outlet temperature is equal to or higher than the set temperature;
When the ambient temperature is lower than the specific temperature, the set temperature is set to a first temperature, and when the ambient temperature is higher than the specific temperature, the set temperature is set to a second temperature higher than the first temperature. A temperature switching unit,
The atmosphere monitoring device in a facility according to claim 1, further comprising: The temperature setting unit,
A first temperature setting unit that turns off the cooling device when the outlet temperature is lower than the first temperature, and turns on the cooling device when the outlet temperature is equal to or higher than the first temperature;
A second temperature setting unit that turns off the cooling device when the outlet temperature is lower than the second temperature, and turns on the cooling device when the outlet temperature is equal to or higher than the second temperature;
Consisting of
The temperature switching unit connects the first temperature setting unit to the cooling device when the ambient temperature is lower than the specific temperature, and sets the second temperature setting unit when the ambient temperature is equal to or higher than the specific temperature. The equipment atmosphere monitoring device according to claim 2, which is connected to a cooling device. A flow rate detector for detecting a flow rate of the atmosphere flowing through the sampling pipe,
A moisture calculating unit that calculates an amount of moisture contained in the atmosphere based on the second temperature and the flow rate;
3. The apparatus according to claim 2, further comprising: a concentration correction unit configured to correct a detection value of the concentration of the gas detected by the gas detector based on the moisture content when the temperature switching unit sets the set temperature to the second temperature. 4. The equipment atmosphere monitoring device according to claim 3.   5. The equipment atmosphere monitoring device according to claim 1, wherein the cooling device includes a Peltier element that transfers heat of the atmosphere passing through the dehumidifying unit. 6.   The equipment atmosphere monitoring device according to any one of claims 1 to 5, wherein the cooling device includes a heat radiating part that radiates heat of the atmosphere passing through the dehumidifying part to the surroundings.   The equipment atmosphere monitoring device according to claim 6, wherein the heat radiating unit includes an air-cooled fin.   The equipment atmosphere monitoring device according to any one of claims 1 to 7, further comprising an air-cooled cooling unit provided upstream of the dehumidification unit and configured to reduce the temperature of the atmosphere to the ambient temperature.   The equipment atmosphere monitoring device according to any one of claims 1 to 8, wherein the gas detector is a heat conduction type hydrogen detector or a magnetic wind type oxygen detector.   The atmosphere monitoring device according to any one of claims 1 to 9, wherein the facility is a reactor containment vessel or a filter vent device. An extraction step of extracting a part of the atmosphere in the facility using a sampling pipe,
A dehumidifying step of dehumidifying the atmosphere in a dehumidifying unit provided in the sampling pipe,
A cooling step of lowering the temperature of the atmosphere using a cooling device provided in the dehumidifying unit,
An ambient temperature detecting step of detecting an ambient temperature of the cooling device using an ambient temperature detector,
A temperature at which the cooling device is controlled in the first mode when the ambient temperature is lower than the specific temperature, and the cooling device is controlled in a second mode different from the first mode when the ambient temperature is equal to or higher than the specific temperature. A control step;
A detection step of detecting a predetermined gas contained in the atmosphere using a gas detector provided downstream of the dehumidifying section,
A method for monitoring the atmosphere in a facility, comprising: A component set for use in the facility atmosphere monitoring device according to any one of claims 1 to 10, wherein
A component set for a facility atmosphere monitoring device, comprising: the cooling device, the ambient temperature detector, and the temperature control unit.

Images