Ventilation and air conditioning system in nuclear facility and method for operating ventilation and air conditioning system

Abstract

To solve the problems of air pollution and public exposure, and to achieve ventilation air conditioning operation of a controlled area by a recirculation system.SOLUTION: In a ventilation and air conditioning system in a nuclear facility according to the present invention, a radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to a first exhaust duct via a first connecting duct, and a recirculation duct that recirculates air in the radiation controlled area to a supply air processing device is connected to an intermediate portion of the first connecting duct. A first opening and closing device and a second opening and closing device are installed in the middle of the recirculation duct, a portion between the first opening and closing device and the second opening and closing device is connected to the low-dose area by a second connecting duct, and opening and closing operations of the first opening and closing device and the second opening and closing device are switched according to a once-through operation in which all of the supply air is exhausted as the ventilation and air conditioning system and a recirculation operation in which a part of the exhaust air is returned to the supply air side as the ventilation and air conditioning system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ventilation and air conditioning system in a nuclear facility and an operating method of the ventilation and air conditioning system, and more particularly to a ventilation and air conditioning system in a nuclear facility that is suitable for applying a recirculation system as a ventilation and air conditioning method in a radiation controlled area of ​​the nuclear facility and an operating method of the ventilation and air conditioning system. [Background technology]

[0002] In nuclear power plants, fans (blower and / or exhaust fans) are used to ventilate the reactor building. In particular, in radiation controlled areas (hereinafter referred to as controlled areas), a ventilation and air conditioning system called the once-through system, in which all intake air is exhausted, is generally used.

[0003] This once-through system, compared to a system called recirculation, in which part of the exhaust air is returned to the intake air side, results in a larger air volume in controlled areas such as reactor buildings, so the adoption of the recirculation system is being considered.

[0004] An example of such a ventilation air-conditioning system that employs a recirculation method is disclosed in Patent Document 1, for example.

[0005] Patent Document 1 states that if the recirculation fan that operates only in emergencies in conventional central control room ventilation and air conditioning equipment can be replaced by another fan, the system will have a simpler and more reliable configuration, and that in emergencies it is necessary to reduce the exhaust volume compared to normal times, but because exhaust fans with a constant rotation speed have strength issues, the role of the recirculation fan that operates only in emergencies can be replaced by two intake fans, and in the event of a plant emergency, the small amount of outside air taken in by the operation of one intake fan and the air passing through the recirculation duct will pass through an intake unit and a recirculation filter unit arranged in parallel, becoming air with low radiation performance and adjusted to an appropriate temperature and humidity, and that by changing the rotation speed of the exhaust fan using an inverter to control the exhaust volume, more stable operation than before will be possible.

[0006] Reducing the air volume in controlled areas such as reactor buildings has the advantage of reducing the amount of electricity consumed by operating fans and extending the life of equipment such as filters. In particular, reducing the air volume in controlled areas such as reactor buildings is an effective measure in emergencies such as when volcanic ash falls following a volcanic eruption, so recirculation systems are being considered as ventilation and air conditioning methods for controlled areas such as reactor buildings.

[0007] On the other hand, reducing the air volume in controlled areas such as reactor buildings reduces the exhaust wind speed from the exhaust stack, which raises the issue that the regulatory requirements for exhaust set out in the installation and / or construction permits for the nuclear facility may not be met.

[0008] To solve this problem, Patent Document 2, for example, is an example of a control system for a ventilation and air conditioning system that takes into account the exhaust wind speed from an exhaust stack.

[0009] Patent Document 2 describes a ventilation and air conditioning system for a nuclear power plant that includes an intake air conditioning system with a cooler and / or heater, a radioactive area such as a reactor building to which outside air supplied from the intake air conditioning system is guided, an exhaust air conditioning system that guides exhaust air from this radioactive area, an exhaust stack that discharges the exhaust air from the exhaust air conditioning system from a high place, and a blow-up height adjustment device that adjusts and sets the blow-up height from the exhaust stack to be approximately constant regardless of the volume of exhaust air from the radioactive area, in order to maintain a substantially constant height of air from the exhaust stack regardless of the volume of exhaust air from the radioactive area, thereby significantly reducing public exposure dose below a specified value and reducing power energy consumption. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 9-159207 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-147717 Summary of the Invention [Problem to be solved by the invention]

[0011] Compared to the once-through system, the recirculation system as a ventilation and air conditioning system is effective in terms of reusing heat and / or adjusting temperature and humidity, reducing the intake of salt and dust from the outside air, and isolating it from external hazards.

[0012] However, in nuclear power plants, the recirculation system is not applied to controlled areas for the following two reasons:

[0013] The first issue is indoor air pollution, and if highly radioactive air continues to be recirculated, the radiation dose in the controlled area will increase. The second issue is public exposure dose, and in nuclear power plants, the impact on the surrounding environment is reduced by blowing the exhaust air up from the exhaust stack and dispersing it to a high altitude, but when the recirculation method is applied, the exhaust air volume is reduced, and there is a risk that the public exposure dose specified in the installation and / or construction permit will not be met.

[0014] In the above-mentioned Patent Document 1, rationalization is attempted by not providing a dedicated fan for the recirculation line, but it is only applicable to air conditioning for central control rooms, that is, to air conditioning for non-controlled areas, and does not take into consideration air conditioning for controlled areas.

[0015] Furthermore, while Patent Document 2 mentioned above takes into consideration the exhaust air velocity, it does not consider ventilation and air-conditioning systems that use a recirculation method. It also describes a reduction in electricity consumption due to a reduction in air volume, but the power of the fan is constant, and it is difficult to achieve a reduction in electricity consumption solely by controlling the air volume adjustment mechanism. Furthermore, while using an inverter is an option, applying an inverter to a nuclear facility is technically difficult from the standpoint of reliability.

[0016] As described above, none of the patent documents realizes the operation of ventilation and air conditioning in a controlled area using a recirculation system.

[0017] The present invention has been made in consideration of the above points, and its object is to provide a ventilation and air-conditioning system for a nuclear facility that solves the problems of air pollution and public radiation exposure, and that makes it possible to operate ventilation and air-conditioning in controlled areas using a recirculation system, and a method for operating such a ventilation and air-conditioning system. [Means for solving the problem]

[0018] In order to achieve the above object, the ventilation and air conditioning system for a nuclear facility of the present invention comprises an air intake treatment device, a plurality of air intake fans that supply air from the air intake treatment device to a radiation controlled area, a plurality of exhaust fans that exhaust air from the radiation controlled area, and an exhaust stack that releases the air exhausted from the plurality of exhaust fans into the atmosphere, a ventilation and air conditioning system for a nuclear facility, wherein the air intake treatment device and each of the plurality of air intake fans are connected by a first air intake duct, each of the plurality of air intake fans and the radiation controlled area are connected by a second air intake duct, the radiation controlled area and each of the plurality of exhaust fans are connected by a first exhaust duct, and each of the plurality of exhaust fans and the exhaust stack are connected by a second exhaust duct; The radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to the first exhaust duct via a first connecting duct, and a recirculation duct for recirculating air within the radiation controlled area is connected to the air supply treatment device in the middle of the first connecting duct, a first opening / closing device and a second opening / closing device are installed in the middle of the recirculation duct, and the first opening / closing device, the second opening / closing device, and the low-dose area are connected by a second connecting duct; The ventilation air conditioning system is characterized by switching the opening and closing operations of the first opening and closing device and the second opening and closing device depending on whether the system is in once-through operation, in which all of the supply air is exhausted, or in recirculation operation, in which part of the exhaust air is returned to the supply air side.

[0019] In order to achieve the above object, the present invention also provides a method for operating a ventilation and air conditioning system in a nuclear facility, comprising: an air supply treatment device; a plurality of air supply fans that supply air from the air supply treatment device to a radiation controlled area; a plurality of exhaust fans that exhaust air from the radiation controlled area; and an exhaust stack that releases the air exhausted from the plurality of exhaust fans into the atmosphere, In operating a ventilation and air conditioning system in a nuclear facility, the air intake treatment device and each of the plurality of air intake fans are connected by a first air intake duct, each of the plurality of air intake fans and the radiation controlled area are connected by a second air intake duct, the radiation controlled area and each of the plurality of exhaust fans are connected by a first exhaust duct, and each of the plurality of exhaust fans and the exhaust stack are connected by a second exhaust duct, The radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to the first exhaust duct via a first connecting duct, and a recirculation duct for recirculating air within the radiation controlled area is connected to the air supply treatment device in the middle of the first connecting duct, a first opening / closing device and a second opening / closing device are installed in the middle of the recirculation duct, and the first opening / closing device, the second opening / closing device, and the low-dose area are connected by a second connecting duct; The opening and closing operations of the first opening and closing device and the second opening and closing device are switched depending on whether the ventilation air-conditioning system is in a once-through operation in which all of the supply air is exhausted or in a recirculation operation in which a portion of the exhaust air is returned to the supply air side, In the summer when the cooling load is high and in the winter when the heating load is high, the basic operation mode is the recirculation operation, and only when the regulatory requirements at the time of exhaust are not met is the operation switched to the once-through operation.

[0020] In order to achieve the above object, the present invention also provides a method for operating a ventilation and air conditioning system in a nuclear facility, comprising: an air supply treatment device; a plurality of air supply fans that supply air from the air supply treatment device to a radiation controlled area; a plurality of exhaust fans that exhaust air from the radiation controlled area; and an exhaust stack that releases the air exhausted from the plurality of exhaust fans into the atmosphere, In operating a ventilation and air conditioning system in a nuclear facility, the air intake treatment device and each of the plurality of air intake fans are connected by a first air intake duct, each of the plurality of air intake fans and the radiation controlled area are connected by a second air intake duct, the radiation controlled area and each of the plurality of exhaust fans are connected by a first exhaust duct, and each of the plurality of exhaust fans and the exhaust stack are connected by a second exhaust duct, The radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to the first exhaust duct via a first connecting duct, and a recirculation duct for recirculating air within the radiation controlled area is connected to the air supply treatment device in the middle of the first connecting duct, a first opening / closing device and a second opening / closing device are installed in the middle of the recirculation duct, and the first opening / closing device, the second opening / closing device, and the low-dose area are connected by a second connecting duct; The opening and closing operations of the first opening and closing device and the second opening and closing device are switched depending on whether the ventilation air-conditioning system is in a once-through operation in which all of the supply air is exhausted or in a recirculation operation in which a portion of the exhaust air is returned to the supply air side, When an external hazard occurs that makes it disadvantageous to take in outside air while the once-through operation is being performed as the basic operation mode, the operation mode is temporarily switched to the recirculation operation. [Effects of the Invention]

[0021] According to the present invention, the problems of air pollution and public exposure dose are solved, and it becomes possible to realize ventilation and air conditioning operation in controlled areas using a recirculation system. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing a first embodiment of the ventilation and air-conditioning system for a nuclear facility according to the present invention, and is a diagram showing the state of the ventilation and air-conditioning system for a nuclear facility during once-through operation. [Figure 2]FIG. 1 is a diagram showing a first embodiment of the ventilation and air-conditioning system for a nuclear facility according to the present invention, and is a diagram showing the state of the ventilation and air-conditioning system for a nuclear facility during recirculation operation. [Figure 3] FIG. 10 is a second embodiment of the ventilation and air-conditioning system for a nuclear facility according to the present invention, showing the state of the ventilation and air-conditioning system for a nuclear facility during once-through operation. DETAILED DESCRIPTION OF THE INVENTION

[0023] The ventilation and air-conditioning system for a nuclear facility and the method of operating the ventilation and air-conditioning system of the present invention will be described below based on the illustrated embodiment. Note that the same reference numerals are used for the same components in each drawing.

[0024] First, before describing an embodiment of a ventilation and air-conditioning system for a nuclear facility according to the present invention, some of the symbols used in the embodiment will be explained.

[0025] In this embodiment, symbols 2a and 2b are first and second air supply ducts, and symbols 5a and 5b are first and second exhaust ducts, which are pipes that transport air for the purpose of air conditioning and ventilation within the reactor building.

[0026] Furthermore, reference numerals 3 (3a, 3b, 3c, 3d) are intake fans, and reference numerals 6 (6a, 6b, 6c, 6d) are exhaust fans, which are machines that impart energy to gases through the rotational movement of impellers, with an energy per unit mass of less than 25 kJ / kg, and are installed for the purpose of blowing air. Note that in the diagram, the white areas indicate that the intake fan 3 and exhaust fan 6 are in operation, and the black areas indicate that the intake fan 3 and exhaust fan 6 are stopped.

[0027] Furthermore, reference numeral 4 denotes a radiation controlled area (controlled area), which is divided into a high-dose area 9 and a low-dose area 10, and the areas affected by radiation exposure are determined by law. Reference numeral 7 denotes an exhaust stack, which is equipment that diffuses exhaust gas from within the radiation controlled area 4 into the atmosphere from a high place. At nuclear facilities, laws and regulations require that the impact of exhaust gas on the surrounding environment be reduced, and the height and exhaust speed of the exhaust stack 7 are set to satisfy the regulations set forth by law.

[0028] Furthermore, reference numeral 8 denotes a throttle mechanism, which is provided at the top end of the exhaust stack 7 and narrows the cross-sectional area of ​​the pipe through which the fluid passes, and is made up of, for example, a needle valve, a damper, etc. For a fluid with a constant flow rate, the smaller the cross-sectional area of ​​the pipe, the higher the flow velocity, so operating the throttle mechanism 8 is expected to increase the pumping speed. In this embodiment, this refers particularly to a mechanism that allows the cross-sectional area of ​​the pipe to be changed in order to adjust the pumping speed.

[0029] Furthermore, reference numerals 11, 12, 19a, 19b, and 20 denote the first, second, third, fourth, and fifth opening and closing devices, which are made up of valves, dampers, etc. and regulate the flow of fluid. In the drawing, the white parts indicate that the first, second, third, fourth, and fifth opening and closing devices 11, 12, 19a, 19b, and 20 are in an open or adjusted open state (the opening and closing devices are half-open), and the black parts indicate that the first, second, third, fourth, and fifth opening and closing devices 11, 12, 19a, 19b, and 20 are in a closed state. [Example]

[0030] Figures 1 and 2 show a first embodiment of the ventilation and air conditioning system for a nuclear facility according to the present invention. Figure 1 shows the ventilation and air conditioning system for a nuclear facility in once-through operation, and Figure 2 shows the ventilation and air conditioning system for a nuclear facility in recirculation operation.

[0031] As shown in Figures 1 and 2, the ventilation and air conditioning system in the nuclear facility of this embodiment is roughly composed of an air supply treatment device 1, multiple (four in this embodiment) air supply fans 3 (3a, 3b, 3c, 3d) that supply air from the air supply treatment device 1 to the radiation controlled area 4, multiple (four in this embodiment) exhaust fans 6 (6a, 6b, 6c, 6d) that exhaust air from the radiation controlled area 4, and an exhaust stack 7 that releases the air exhausted from the multiple (four) exhaust fans 6a, 6b, 6c, 6d into the atmosphere.

[0032] The above-mentioned air intake treatment device 1 and each of the four air intake fans 3a, 3b, 3c, and 3d are connected by a first air intake duct 2a, each of the four air intake fans 3a, 3b, 3c, and 3d are connected to the radiation controlled area 4 by a second air intake duct 2b, the radiation controlled area 4 and each of the four exhaust fans 6a, 6b, 6c, and 6d are connected by a first exhaust duct 5a, and each of the four exhaust fans 6a, 6b, 6c, and 6d are connected to the exhaust stack 7 by a second exhaust duct 5b and duct 25.

[0033] In this embodiment, the radiation control area 4 is divided into a high-dose area 9 and a low-dose area 10 (examples of thresholds for the high-dose area 9 and the low-dose area 10 are set to a radioactive material density in the air of 3.7 × 10 - (-4)[Bq / cm 3 In the low-dose area 10, values ​​lower than the above threshold (e.g., 3.7 × 10 - (-5)[Bq / cm 3]), so meters are installed and, if a concentration approaching the standard is recorded, the recirculation operation is stopped), the high-dose area 9 is connected to the first exhaust duct 5a via first connecting ducts 23a and 23b, and a recirculation duct 13 that recirculates air within the radiation-controlled area 4 to the air supply device 1 is connected to the first connecting ducts 23a and 23b, and a first opening / closing device 11 and a second opening / closing device 12 are installed in the middle of this recirculation duct 13, and the first opening / closing device 11, the second opening / closing device 12 and the low-dose area 10 are connected by a second connecting duct 24, and the opening and closing operations of the first opening / closing device 11 and the second opening / closing device 12 are switched depending on whether the ventilation / air-conditioning system is in once-through operation, in which all of the intake air is exhausted, or in recirculation operation, in which part of the exhaust air is returned to the intake side.

[0034] To explain in more detail, when the ventilation and air conditioning system is in once-through operation, exhaust from the high-dose area 9 is always discharged into the atmosphere via the first connecting ducts 23a and 23b, the first exhaust duct 5a, the three exhaust fans 6a, 6b, and 6c, the second exhaust duct 5b, the duct 25, and the exhaust stack 7, as shown by the arrows in Figure 1, by opening and closing the first opening and closing device 11 and the second opening and closing device 12.

[0035] On the other hand, when the ventilation and air conditioning system is in once-through operation, exhaust from the low-dose area 10 is achieved by the opening and closing operations of the first opening and closing device 11 and the second opening and closing device 12, and the air is sent via the second connecting duct 24 to the first connecting duct 23b, the first exhaust duct 5a, the three exhaust fans 6a, 6b, and 6c, the second exhaust duct 5b, duct 25, and the exhaust stack 7, as shown by the arrows in Figure 1. When the ventilation and air conditioning system is in recirculation operation using the recirculation method, exhaust from the low-dose area 10 is achieved by the opening and closing operations of the first opening and closing device 11 and the second opening and closing device 12, and the air is sent via the second connecting duct 24 to the recirculation duct 13, as shown by the arrows in Figure 2.

[0036] That is, when the ventilation and air conditioning system is used in once-through operation, as shown in Figure 1, the first opening and closing device 11 is open and the second opening and closing device 12 is closed, and the entire intake air is exhausted from the high-dose area 9 and the low-dose area 10 via the first connecting ducts 23a, 23b and the second connecting duct 24, the first exhaust duct 5a and the second exhaust duct 5b, the three exhaust fans 6a, 6b, 6c, the duct 25, and the exhaust stack 7, as shown by the arrows in Figure 1; and when the ventilation and air conditioning system is used in recirculation operation, as shown in Figure 2, the first opening and closing device 11 is closed and the second opening and closing device 12 is open, and the entire exhaust air from the low-dose area 10 is returned to the intake air treatment device 1 via the recirculation duct 13, as shown by the arrows in Figure 2.

[0037] Furthermore, the ventilation and air conditioning system in the nuclear facility of this embodiment is equipped with a signal source 14 that emits an operation mode switching signal 15, indicated by a dotted arrow, to the first opening and closing device 11, the second opening and closing device 12, and the four exhaust fans 6a, 6b, 6c, and 6d, and the operation mode switching signal 15 emitted from this signal source 14 can be used to change the opening and closing operation of the first opening and closing device 11 and the second opening and closing device 12, and to change the number of operating exhaust fans 6a, 6b, 6c, and 6d (details will be described later).

[0038] In addition, a throttling mechanism 8 is provided at the tip of the exhaust pipe 7 to narrow the cross-sectional area inside the exhaust pipe 7 through which the exhausted air passes, and by operating the throttling mechanism 8 when the air volume in the radiation controlled area 4 changes, the flow rate of the exhausted air during exhaust can be maintained.

[0039] That is, the operation mode switching signal 15 from the signal source 14 is transmitted to the first opening / closing device 11, the second opening / closing device 12, and the four exhaust fans 6a, 6b, 6c, and 6d, and at the same time is transmitted to the throttling mechanism 8 (indicated by the dotted arrow), and by operating the throttling mechanism 8 in response to the operation mode switching signal 15 from the signal source 14, it is possible to maintain the flow rate during exhaust when the number of operating exhaust fans 6a, 6b, 6c, and 6d is reduced (for example, when the operation of the three exhaust fans 6a, 6b, and 6c shown in FIG. 1 is reduced to the operation of the single exhaust fan 6a shown in FIG. 2).

[0040] More specifically, the ventilation and air conditioning system for the radiation-controlled area 4 in the nuclear power plant supplies air by blowing it from the air intake treatment device 1 through the first and second intake ducts 2a and 2b to the radiation-controlled area 4 using four intake fans 3a, 3b, 3c, and 3d. The air in the radiation-controlled area 4 is then blown to the exhaust stack 7 through the first and second exhaust ducts 5a, 5b, and duct 25, and exhausted to a high altitude from the exhaust stack 7. A throttle mechanism 8 is installed at the top of the exhaust stack 7, and when the air volume in the radiation-controlled area 4 changes, the throttle mechanism 8 is activated to maintain the exhaust flow rate to meet regulatory requirements. The throttle mechanism 8 is adjusted to take into account the pressure loss caused by its own operation.

[0041] The radiation controlled area 4 is divided into a high-dose area 9 and a low-dose area 10. Exhaust from the high-dose area 9 is always discharged into the atmosphere by opening and closing the first opening and closing device 11 and the second opening and closing device 12, as shown by the arrows in Fig. 1, via the first connecting ducts 23a and 23b, the first exhaust duct 5a, the three exhaust fans 6a, 6b, and 6c, the second exhaust duct 5b, the duct 25, and the exhaust stack 7.

[0042] On the other hand, the exhaust from the low-dose area 10 can be switched to the first exhaust duct 5a or the recirculation duct 13 via the second connecting duct 24 and the first connecting duct 23b by opening and closing the first opening and closing device 11 and the second opening and closing device 12.

[0043] In addition, an operation mode switching signal 15 sent from a signal source 14 changes the open / closed states of the first opening / closing device 11 and the second opening / closing device 12 (changing from the state in which the first opening / closing device 11 is "open" and the second opening / closing device 12 is "closed" in FIG. 1 to the state in which the first opening / closing device 11 is "closed" and the second opening / closing device 12 is "open" in FIG. 2), and changes the number of operating exhaust fans out of four 6a, 6b, 6c, and 6d (changing from the operation of three exhaust fans 6a, 6b, and 6c in FIG. 1 to the operation of one exhaust fan 6a in FIG. 2). At the same time, by sending an operation mode switching signal 15 from the signal source 14 to the throttle mechanism 8 to operate it, the flow rate during exhaust can be maintained even if the number of operating exhaust fans 6 is reduced.

[0044] The ventilation air-conditioning system of this embodiment will be described below using specific numerical values.

[0045] For example, a design air volume of 200,000 m 3 Four units of each of the intake fans 3 and exhaust fans 6 with a capacity of 1000m / h (one of which is a spare unit and normally operates as three units) are installed, and the design ventilation air volume of the high-dose area 9 in the radiation control area 4 is 5,000m 3 / h, and the design ventilation air volume of low-dose area 10 in radiation control area 4 is 50,000 m 3 / h, total design ventilation air volume is 55,000 m 3 Assume a nuclear power plant with a capacity of 1000 kWh.

[0046] During once-through operation in which the ventilation air-conditioning system exhausts all of the intake air, as shown in Figure 1, the first opening / closing device 11 is "open" and the second opening / closing device 12 is "closed", and all of the intake air is exhausted, so the exhaust air volume is 55,000 m, the same as the design ventilation air volume. 3 / h.

[0047] On the other hand, during recirculation operation as a ventilation and air conditioning system, as shown in FIG. 2, the first opening / closing device 11 is "closed" and the second opening / closing device 12 is "opened", and all of the exhaust air from the low-dose area 10 in the radiation controlled area 4 is returned to the air supply processing device 1 on the supply side via the second connecting duct 24 and the recirculation duct 13, so the exhaust air volume is 5000 m3, the same as the designed ventilation air volume of the high-dose area 9 in the radiation controlled area 4. 3 / h. The number of operating exhaust fans 6 is also reduced from three to one. As the exhaust air volume is reduced, the throttle mechanism 8 is adjusted to maintain the flow velocity during exhaust.

[0048] According to this embodiment, the problems of air pollution and public exposure dose are solved, and ventilation and air conditioning operation in the radiation controlled area 4 can be realized by the recirculation system. [Example]

[0049] A second embodiment of the ventilation and air-conditioning system for a nuclear facility according to the present invention is shown in Fig. 3. Fig. 3 is a diagram showing the state of the ventilation and air-conditioning system for a nuclear facility during once-through operation.

[0050] The ventilation and air conditioning system for a nuclear facility of this embodiment shown in Figure 3 has a configuration similar to that described in Example 1, but the ventilation and air conditioning system for a nuclear facility of this embodiment shown in Figure 3 is equipped with an air intake treatment device 1 that includes a hood 16 that protects the equipment from natural falling objects and flying objects such as snow and volcanic ash, and a second air intake treatment device 17 that processes natural falling objects and flying objects and supplies air to the air intake treatment device 1.

[0051] In addition, in the ventilation and air conditioning system of the nuclear facility of this embodiment, a branch duct 13a is installed midway through the recirculation duct 13, which branches off from the recirculation duct 13 and returns to the recirculation duct 13, and a recirculation filter device 18 consisting of a charcoal filter or a high-performance particle filter is installed midway through this branch duct 13a to keep the air recirculating within the recirculation duct 13 in a normal state, and a third opening and closing device 20 is installed in a position parallel to the recirculation filter device 18 of the recirculation duct 13, and a fourth opening and closing device 19a and a fifth opening and closing device 19b are installed on the branch duct 13a upstream (front side) and downstream (rear side) of the recirculation filter device 18.

[0052] By opening and closing the third, fourth and fifth opening and closing devices 20, 19a and 19b, the air recirculating in the recirculation duct 13 can be switched between a state in which it passes through the recirculation filter device 18 and a state in which it does not.

[0053] Furthermore, in the ventilation and air conditioning system of the nuclear facility of this embodiment, an exhaust stack radiation monitor 21 that monitors the radiation level during exhaust is installed in the middle of the duct 25 connecting the second exhaust duct 5b and the exhaust stack 7, and if this exhaust stack radiation monitor 21 observes a radiation level that does not meet the predetermined regulatory requirements during exhaust, it sends a signal 22 to stop recirculation operation to the signal source 14, and the operating mode switching signal 15 from this signal source 14 switches the opening and closing operation of the first opening and closing device 11 and the second opening and closing device 12, thereby returning the operating state from recirculation operation to once-through operation.

[0054] More specifically, in the second embodiment, a hood 16 is provided on the air treatment device 1 to protect the equipment from natural falling or flying objects such as snow and volcanic ash. The air is then supplied to the building through a second air treatment device 17, and recirculation operation is carried out in the same manner as in the first embodiment.

[0055] A recirculation filter device 18 is provided midway through the recirculation duct 13 to keep the recirculated air clean. A fourth opening / closing device 19a, a fifth opening / closing device 19b, and a third opening / closing device 20 are provided before, after, and in parallel with the recirculation duct 13, and by opening and closing these opening / closing devices it is possible to switch between a state in which the recirculated air passes through the recirculation filter 18 and a state in which it does not.

[0056] In addition, a portion of the air exhausted from the exhaust stack 7 is extracted, and the amount of radioactivity in the exhaust is monitored by the exhaust stack radiation monitor 21. Even when the flow rate during exhaust is maintained by the throttling mechanism 8, if a radiation amount that does not meet the specified regulatory requirements during exhaust is observed, the exhaust stack radiation monitor 21 sends a signal 22 to stop recirculation operation, and the operating state is returned from recirculation operation to once-through operation, thereby providing an interlock function that increases the exhaust volume and satisfies the regulatory requirements.

[0057] Even with the configuration of this embodiment, the effects are the same as those of the first embodiment. [Example]

[0058] Next, as a third embodiment of the present invention, a method for operating the ventilation and air-conditioning system in a nuclear facility described in the first and second embodiments will be described.

[0059] The third embodiment relates to an operation method for switching the operation mode from the viewpoint of reheat utilization and power consumption reduction.

[0060] That is, as in the first and second embodiments, the opening and closing operations of the first opening and closing device 11 and the second opening and closing device 12 are switched depending on whether the ventilation and air conditioning system is in once-through operation, in which all of the intake air is exhausted, or in recirculation operation, in which part of the exhaust air is returned to the intake air side. However, in this embodiment, in the summer when the cooling load is high and in the winter when the heating load is high, the basic operating mode is recirculation operation, and the system is switched to once-through operation only when the regulatory requirements for exhaust are not met.

[0061] In other words, in the summer when the cooling load is high and in the winter when the heating load is high, the basic operating mode is the recirculation mode, and only when the regulatory requirements for exhaust are not met is the system switched to the once-through mode. However, this does not apply when the heat load of the equipment is high and it is necessary to remove heat from the building even in winter. Also, in the period between summer and winter when the heating and cooling load is low, the once-through mode is applied for operation to reduce the radiation dose inside the reactor building.

[0062] The method of operating the ventilation and air conditioning system in a nuclear facility according to this embodiment solves the problems of air pollution and public exposure dose, realizes reheat utilization and reduced power consumption, and makes it possible to operate the ventilation and air conditioning system in the radiation controlled area 4 using a recirculation method according to the season. [Example]

[0063] Next, as a fourth embodiment of the present invention, a method for operating the ventilation and air-conditioning system in a nuclear facility described in the first and second embodiments will be described.

[0064] The fourth embodiment relates to an operation method for switching the operation mode from the viewpoint of countermeasures against external hazards.

[0065] That is, as in the above-mentioned first and second embodiments, the opening and closing operations of the first opening and closing device 11 and the second opening and closing device 12 are switched depending on whether the ventilation and air conditioning system is in once-through operation, in which all of the intake air is exhausted, or in recirculation operation, in which part of the exhaust air is returned to the intake air side. However, in this embodiment, when the basic operating mode is once-through operation, if an external hazard occurs that makes it disadvantageous to take in outside air, the operating mode is temporarily switched to recirculation operation.

[0066] In other words, when operating in the once-through mode as the basic operating mode, if an external hazard occurs that makes it disadvantageous to take in outside air, such as volcanic ash fall due to a volcanic eruption, the operating mode will be temporarily switched to the recirculation mode.

[0067] In particular, if it has been confirmed in advance that the decrease in exhaust speed is temporary and meets the public exposure dose specified in the installation and / or construction approval, the interlock function that switches the operation mode from the recirculation system to the once-through system when the radiation dose increases is simultaneously released, and when the influence of the external hazard has disappeared, the operation mode is returned to the once-through system.

[0068] This method of operating the ventilation and air conditioning system in a nuclear facility according to this embodiment solves the problems of air pollution and public exposure dose, and even if an external hazard occurs, it becomes possible to operate the ventilation and air conditioning system in the radiation controlled area 4 using a recirculation method.

[0069] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0070] 1...air intake treatment device, 2a...first air intake duct, 2b...second air intake duct, 3, 3a, 3b, 3c, 3d...air intake fan, 4...radiation controlled area (controlled area), 5a...first exhaust duct, 5b...second exhaust duct, 6, 6a, 6b, 6c, 6d...exhaust fan, 7...exhaust stack, 8...throttling mechanism, 9...high dose area in radiation controlled area, 10...low dose area in radiation controlled area, 11...first opening / closing device, 12...second Opening and closing device, 13...recirculation duct, 13a...branch duct, 14...signal source, 15...operation mode switching signal, 16...hood, 17...second air supply treatment device, 18...recirculation filter device, 19a...fourth opening and closing device, 19b...fifth opening and closing device, 20...third opening and closing device, 21...exhaust stack radiation monitor device, 22...recirculation operation stop signal, 23a, 23b...first connecting duct, 24...second connecting duct, 25...duct.

Claims

1. an air supply treatment device, a plurality of air supply fans that supply air from the air supply treatment device to a radiation controlled area, a plurality of exhaust fans that exhaust air from the radiation controlled area, and an exhaust stack that releases the air exhausted from the plurality of exhaust fans into the atmosphere; a ventilation and air conditioning system for a nuclear facility, wherein the air supply treatment device and each of the plurality of air supply fans are connected by a first air supply duct, each of the plurality of air supply fans and the radiation controlled area are connected by a second air supply duct, the radiation controlled area and each of the plurality of exhaust fans are connected by a first exhaust duct, and each of the plurality of exhaust fans and the exhaust stack are connected by a second exhaust duct; the radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to the first exhaust duct via a first connecting duct, and a recirculation duct for recirculating air within the radiation controlled area is connected to the air supply treatment device midway through the first connecting duct; a first opening / closing device and a second opening / closing device are installed in the middle of the recirculation duct, and a second connecting duct is connected between the first opening / closing device and the second opening / closing device and the low-dose area; A ventilation and air conditioning system for a nuclear facility, characterized in that the opening and closing operations of the first opening and closing device and the second opening and closing device are switched depending on whether the ventilation and air conditioning system is in once-through operation, in which all of the intake air is exhausted, or in recirculation operation, in which a portion of the exhaust air is returned to the intake air side.

2. 2. The ventilation and air conditioning system for a nuclear facility according to claim 1, during the once-through operation, exhaust from the high-dose area is always discharged to the atmosphere via the first connection duct, the first exhaust duct, the exhaust fan, the second exhaust duct, and the exhaust stack by opening and closing operations of the first opening and closing device and the second opening and closing device; On the other hand, exhaust from the low-dose area during the once-through operation is achieved by blowing air through the second connecting duct to the first exhaust duct, the exhaust fan, the second exhaust duct and the exhaust stack by opening and closing the first opening and closing device and the second opening and closing device, and exhaust from the low-dose area during the recirculation operation is achieved by blowing air through the second connecting duct to the recirculation duct by opening and closing the first opening and closing device and the second opening and closing device.

3. 3. The ventilation and air conditioning system for a nuclear facility according to claim 2, A ventilation and air conditioning system for a nuclear facility, characterized in that during the once-through operation, the first opening and closing device is open and the second opening and closing device is closed, and the entire amount of intake air from the high-dose area and the low-dose area is exhausted via the first and second connecting ducts, the first and second exhaust ducts, the multiple exhaust fans, and the exhaust stack, and during the recirculation operation, the first opening and closing device is closed and the second opening and closing device is open, and the entire amount of exhaust air from the low-dose area is returned to the intake air treatment device via the recirculation duct.

4. 4. The ventilation and air conditioning system for a nuclear facility according to claim 3, the ventilation and air conditioning system for the nuclear facility includes a signal source that transmits an operation mode switching signal to the first opening and closing device, the second opening and closing device, and the plurality of exhaust fans; a ventilation and air conditioning system for a nuclear facility, characterized in that the opening and closing operations of the first opening and closing device and the second opening and closing device are changed and the number of operating exhaust fans is changed in response to the operation mode switching signal transmitted from the signal source.

5. 5. The ventilation and air conditioning system for a nuclear facility according to claim 4, A ventilation and air conditioning system for a nuclear facility, characterized in that a throttling mechanism is provided at the tip of the exhaust stack to narrow the cross-sectional area inside the exhaust stack through which the exhaust air passes, and when the air volume in the radiation controlled area changes, the throttling mechanism is operated to maintain the flow rate during exhaust.

6. 6. The ventilation and air conditioning system for a nuclear facility according to claim 5, a ventilating and air-conditioning system for a nuclear facility, characterized in that the operation mode switching signal from the signal source is transmitted to the first opening and closing device, the second opening and closing device, and the plurality of exhaust fans, and at the same time is transmitted to the throttling mechanism, and by operating the throttling mechanism in response to the operation mode switching signal from the signal source, the flow rate during exhaust is maintained when the number of operating exhaust fans is reduced.

7. 7. The ventilation and air conditioning system for a nuclear facility according to claim 6, A ventilation and air conditioning system for a nuclear facility, characterized in that the air intake treatment device is equipped with a hood that protects against naturally falling objects and / or flying objects, and a second air intake treatment device that processes naturally falling objects and / or flying objects and supplies air to the air intake treatment device.

8. 7. The ventilation and air conditioning system for a nuclear facility according to claim 6, A branch duct is installed midway along the recirculation duct, branching off from the recirculation duct and returning to the recirculation duct, and a recirculation filter device is installed midway along the branch duct to keep the air recirculating in the recirculation duct in a normal state, and a third opening and closing device is installed in the recirculation duct in a position parallel to the recirculation filter device, and fourth and fifth opening and closing devices are installed on the branch ducts upstream and downstream of the recirculation filter device, A ventilation and air conditioning system for a nuclear facility, characterized in that opening and closing of the third, fourth, and fifth opening and closing devices switches between a state in which the air recirculating in the recirculation duct passes through the recirculation filter device and a state in which it does not pass through.

9. 9. The ventilation and air conditioning system for a nuclear facility according to claim 8, 1. A ventilation and air conditioning system for a nuclear facility, wherein the recirculation filter device comprises a charcoal filter or a high-performance particle filter.

10. 7. The ventilation and air conditioning system for a nuclear facility according to claim 6, a stack radiation monitor for monitoring radiation levels during exhaust, the stack radiation monitor being installed midway through the duct connecting the second exhaust duct and the exhaust stack; and when the stack radiation monitor observes a radiation level that does not meet predetermined regulatory requirements during exhaust, the stack radiation monitor transmits a signal to the signal source to stop recirculation operation, and the signal source switches the opening and closing operations of the first opening and closing device and the second opening and closing device to return the operating state from recirculation operation to once-through operation.

11. an air supply treatment device, a plurality of air supply fans that supply air from the air supply treatment device to a radiation controlled area, a plurality of exhaust fans that exhaust air from the radiation controlled area, and an exhaust stack that releases the air exhausted from the plurality of exhaust fans into the atmosphere; In operating a ventilation and air conditioning system in a nuclear facility, the air supply treatment device and each of the plurality of air supply fans are connected by a first air supply duct, each of the plurality of air supply fans and the radiation controlled area are connected by a second air supply duct, the radiation controlled area and each of the plurality of exhaust fans are connected by a first exhaust duct, and each of the plurality of exhaust fans and the exhaust stack are connected by a second exhaust duct, the radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to the first exhaust duct via a first connecting duct, and a recirculation duct for recirculating air within the radiation controlled area is connected to the air supply treatment device midway through the first connecting duct; a first opening / closing device and a second opening / closing device are installed in the middle of the recirculation duct, and a second connecting duct is connected between the first opening / closing device and the second opening / closing device and the low-dose area; The opening and closing operations of the first opening and closing device and the second opening and closing device are switched depending on whether the ventilation air-conditioning system is in a once-through operation in which all of the supply air is exhausted or in a recirculation operation in which a portion of the exhaust air is returned to the supply air side, a ventilation and air-conditioning system for a nuclear facility, characterized in that the basic operation mode is the recirculation operation in summer when the cooling load is high and in winter when the heating load is high, and the operation mode is switched to the once-through operation only when the regulatory requirements for exhaust are not met.

12. 12. A method for operating a ventilation and air conditioning system in a nuclear facility according to claim 11, A method for operating a ventilation and air-conditioning system in a nuclear facility, characterized in that the once-through operation is performed during an intermediate period between the summer and winter when the heating and cooling load is low.

13. an air supply treatment device, a plurality of air supply fans that supply air from the air supply treatment device to a radiation controlled area, a plurality of exhaust fans that exhaust air from the radiation controlled area, and an exhaust stack that releases the air exhausted from the plurality of exhaust fans into the atmosphere; In operating a ventilation and air conditioning system in a nuclear facility, the air supply treatment device and each of the plurality of air supply fans are connected by a first air supply duct, each of the plurality of air supply fans and the radiation controlled area are connected by a second air supply duct, the radiation controlled area and each of the plurality of exhaust fans are connected by a first exhaust duct, and each of the plurality of exhaust fans and the exhaust stack are connected by a second exhaust duct, the radiation controlled area is divided into a high-dose area and a low-dose area, the high-dose area is connected to the first exhaust duct via a first connecting duct, and a recirculation duct for recirculating air within the radiation controlled area is connected to the air supply treatment device midway through the first connecting duct; a first opening / closing device and a second opening / closing device are installed in the middle of the recirculation duct, and a second connecting duct is connected between the first opening / closing device and the second opening / closing device and the low-dose area; The opening and closing operations of the first opening and closing device and the second opening and closing device are switched depending on whether the ventilation air-conditioning system is in a once-through operation in which all of the supply air is exhausted or in a recirculation operation in which a portion of the exhaust air is returned to the supply air side, A method for operating a ventilation and air conditioning system in a nuclear facility, characterized in that when an external hazard occurs that makes it disadvantageous to take in outside air while the once-through operation is being performed as the basic operation mode, the operation mode is temporarily switched to the recirculation operation.

14. 14. A method for operating a ventilation and air conditioning system in a nuclear facility according to claim 13, comprising: an interlock function for switching the operation mode from the recirculation operation to the once-through operation due to an increase in radiation dose is released when it has been confirmed in advance that the decrease in exhaust speed is temporary and that the decrease satisfies the specified value of public exposure amount set forth in the installation and / or construction approval, and when the influence of the external hazard has disappeared, the operation mode is returned to the once-through operation.

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