Piping system for fast reactors

Abstract

To provide a fast reactor piping system that can effectively prevent fires caused by the combustion of sodium in the event of a sodium leak. [Solution] The piping system 2 comprises a piping body 20, an intake unit 50 located in the detection space V, a gas transport pump 70 capable of drawing in and exhausting gas in the detection space V, a detection unit 80, an inert gas supply line 90, a gas supply source 100, a first valve 110 provided on the main line 60, a second valve 120 provided on the inert gas supply line 90, and a control device that controls the open and closed states of the first valve 110 and the second valve 120. When an abnormality occurs, the control device closes the first valve 110 and opens the second valve 120, and supplies inert gas into the detection space V through the inert gas supply line 90.

Description

Technical Field

[0001] The present invention relates to a piping system of a fast reactor.

Background Art

[0002] Conventionally, in the sodium piping of a fast reactor, when sodium leakage occurs, a method of guiding the leaked portion to an external tank and temporarily storing it is common. Further, Patent Document 1 below discloses a configuration for detecting sodium leakage from a pipe by gas sampling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, with the configuration of Patent Document 1 above, although sodium leakage can be detected itself, for example, when the amount of inert gas around the pipe is insufficient, there is a risk that a fire caused by sodium combustion cannot be sufficiently prevented when leakage occurs.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to provide a piping system of a fast reactor that can satisfactorily prevent a fire caused by sodium combustion when sodium leakage occurs.

Means for Solving the Problems

[0006] In a first aspect of the present invention, the present invention comprises a piping body through which sodium flows, a surrounding member that covers the piping body from the outer periphery to form a detection space inside, an intake unit disposed within the detection space, a main line connected to the intake unit, a gas transport pump disposed on the main line and capable of drawing in and exhausting gas in the detection space via the intake unit, a detection unit for detecting sodium contained in the gas flowing through the main line, an inert gas supply line branched from the main line, a gas supply source that supplies inert gas through the inert gas supply line, a first valve provided on the main line, a second valve provided on the inert gas supply line, and the The piping system for a fast reactor includes a control device that can switch the open / closed state of the first valve and the second valve and the operation of the gas transport pump based on the detection result of the detection unit, wherein during normal operation, the control device opens the first valve and closes the second valve, and operates the gas transport pump to pump the gas in the detection space toward the detection unit, and when an abnormality occurs in which sodium is detected in the gas by the detection unit, the first valve is closed, the second valve is opened, and the gas transport pump is operated to supply inert gas to the detection space through the inert gas supply line.

[0007] The piping system of the fast reactor described above further comprises an enclosure that covers the surrounding member from the outer periphery, a drain line capable of discharging sodium from the piping body to the outside, a third valve provided on the drain line, a transfer line capable of discharging sodium that has leaked from the detection space into the space inside the enclosure to the outside, and a fourth valve provided on the transfer line, and the control device may open the third valve and the fourth valve when the abnormality occurs.

[0008] The control device may keep the third valve and the fourth valve closed during normal operation.

[0009] The piping system of the fast reactor described above further comprises an enclosure that covers the surrounding member from the outer periphery, a transfer line capable of discharging sodium that has leaked from the detection space into the space inside the enclosure to the outside, and a fourth valve provided on the transfer line. The control device may open the fourth valve when it determines that the amount of sodium leaked into the space inside the enclosure exceeds a predetermined threshold.

[0010] The piping system of the fast reactor described above further comprises an enclosure that covers the surrounding member from the outer periphery, a transfer line capable of discharging sodium that has leaked from the detection space into the space inside the enclosure to the outside, and a fourth valve provided on the transfer line. The control device keeps the fourth valve open during normal operation, closes the fourth valve when an abnormality occurs, and opens the fourth valve if it is determined that the amount of sodium leaked into the space inside the enclosure exceeds a predetermined threshold while the fourth valve is closed.

[0011] The intake section is a porous tube that extends along the main body of the piping and has a number of openings through which the gas in the detection space can flow. The porous tube includes a first portion that extends toward one side from the portion to which the main line is connected and a second portion that extends toward the other side, and the openings may be formed in either the first portion or the second portion.

[0012] The piping system of the fast reactor described above further comprises a plurality of partition spacers arranged between the piping body and the surrounding member so as to surround the piping body, and the detection space may be formed between the plurality of partition spacers. [Effects of the Invention]

[0013] The present invention provides a piping system for a fast reactor that can effectively prevent fires caused by the combustion of sodium in the event of a sodium leak. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing the configuration of a fast reactor according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of a piping system according to an embodiment of the present invention. [Figure 3] This is a functional block diagram of a control device according to the first embodiment of the present invention. [Figure 4] This flowchart shows the processing flow of the control device according to the first embodiment of the present invention. [Figure 5] This is a functional block diagram of a control device according to a second embodiment of the present invention. [Figure 6] This flowchart shows the processing flow of the control device according to the second embodiment of the present invention. [Modes for carrying out the invention]

[0015] <First Embodiment> (overview) The piping system according to this embodiment is suitably applied to sodium piping in a fast reactor. Detailed configurations will be described later with reference to the drawings, but the main features of the piping system in this embodiment are as follows. In this piping system, a surrounding member constituting a detection space is provided on the outside of the main body of the piping through which sodium flows. During normal operation, gas is sampled from this detection space to detect whether or not sodium leakage has occurred. On the other hand, if a leak is detected, a valve is switched by the control device and inert gas is supplied into the detection space. With this configuration, even if sodium leaks, fire caused by the combustion of sodium can be effectively prevented. The configuration of this piping system and the configuration of the fast reactor including the piping system will be described below with reference to Figures 1 to 3.

[0016] Figure 1 is a schematic diagram showing the configuration of a fast reactor according to an embodiment of the present invention. Figure 2 is a schematic diagram showing the configuration of a piping system according to an embodiment of the present invention. Figure 3 is a functional block diagram of a control device according to the first embodiment of the present invention.

[0017] (Configuration of Fast Reactor 1) The fast reactor 1 according to this embodiment is a tank-type fast reactor. This fast reactor 1 extracts energy while controlling a nuclear fission chain reaction using, for example, uranium, plutonium, or the like as fuel.

[0018] (Configuration of Fast Reactor 1) As shown in FIG. 1, the fast reactor 1 includes a reactor vessel 10, a reactor core 11, an intermediate heat exchanger 12, a coolant circulation pump 13, in-vessel piping 14, a steam generator 15, and a piping system 2.

[0019] The reactor vessel 10 is, for example, a vessel with a diameter of about 15 m to 20 m. The reactor core 11 is housed inside the reactor vessel 10. The reactor core 11 is provided with core fuel containing fissionable material and control rods for controlling the core reactivity. Although not shown in the figure, the control rods are advanced and retracted in the vertical direction by being driven by a control rod drive mechanism. The control rod drive mechanism changes the insertion amount of the control rods between the core fuels. Thereby, the nuclear fission of the core fuel is controlled, and the thermal output in the reactor core 11 is adjusted. The reactor core 11 heats up sodium, which is a liquid metal as the primary coolant. In the following description, liquid sodium may be simply referred to as "sodium". Also, sodium before heating up may be referred to as low-temperature sodium, and sodium that has been heated up to a high-temperature state may be referred to as high-temperature sodium.

[0020] In the reactor vessel 10, a free liquid surface is set, and cover gas such as argon gas is enclosed above the liquid surface. Thereby, the reactor vessel 10 absorbs the increase and decrease in volume due to the temperature change of sodium as the coolant in the gas space above the liquid surface.

[0021] The intermediate heat exchanger 12 has an inlet window for introducing high-temperature sodium and an outlet window for releasing the low-temperature sodium after heat exchange. The intermediate heat exchanger 12 performs heat exchange between the high-temperature sodium that flows in through the inlet window and the sodium that functions as a coolant for the secondary system. Specifically, due to the action of the coolant circulation pump 13, high-temperature sodium that has risen to, for example, 550°C in the reactor core 11 flows into the inlet of the intermediate heat exchanger 12. The incoming high-temperature sodium exchanges heat with the sodium of the secondary system that functions as a secondary coolant, becoming low-temperature sodium whose temperature drops to, for example, 400°C. The low-temperature sodium flows out through the outlet window to the lower part of the reactor vessel 10. The sodium of the secondary system flows into the steam generator 15 through the main body 20 of the piping system 2, which will be described later. In the steam generator 15, the sodium of the secondary system heats water to generate steam for driving a turbine (not shown).

[0022] The coolant circulation pump 13 pumps the low-temperature sodium that has flowed out of the intermediate heat exchanger 12 into the in-core piping 14. The in-core piping 14 guides the low-temperature sodium pumped by the coolant circulation pump 13 to the reactor core 11.

[0023] (Configuration of piping system 2) Next, the configuration of the piping system 2 according to this embodiment will be described. As shown in Figure 2, the piping system 2 comprises a piping body 20, a surrounding member 30, a partition spacer 40, an intake section 50, a main line 60, a gas transport pump 70, a detection unit 80, an inert gas supply line 90, a gas supply source 100, a first valve 110, a second valve 120, an enclosure 130, a drain line 140, a third valve 150, a transfer line 160, a fourth valve 170, a control device 180, and a nitrogen concentration meter 200.

[0024] (Piping body 20) The main piping body 20 forms a loop-shaped pipeline that includes the steam generator 15 mentioned above. Liquid sodium flows inside the main piping body 20 as a secondary coolant. The cross-sectional shape of the main piping body 20 is circular as an example. The direction of extension of the main piping body 20 is determined as appropriate according to the plant design and specifications.

[0025] (Enclosing member 30) The enclosing member 30 is provided to maintain the temperature of the sodium flowing inside the pipe body 20 and ensure its fluidity. The enclosing member 30 has an inner panel 31, an insulating material 32, and an outer panel 33. The inner panel 31 is cylindrical and covers the pipe body 20 from the outer periphery with a gap. The insulating material 32 is attached to the outer surface of the inner panel 31. The insulating material 32 is made of a material with relatively low thermal conductivity, such as rock wool or Fineflex®. The outer surface of the insulating material 32 is covered by the outer panel 33. The outer panel 33 and the inner panel 31 are made of metal and play a role in maintaining the shape of the insulating material 32. The enclosing member 30 covers the pipe body 20 from the outer periphery, thereby forming a detection space V, which will be described later, inside.

[0026] (Partition spacer 40) The partition spacers 40 are positioned between the pipe body 20 and the surrounding member 30, surrounding the pipe body 20. The partition spacers 40 divide the space between the pipe body 20 and the surrounding member 30 into multiple sections in the direction in which the pipe body 20 extends. In other words, multiple partition spacers 40 are arranged at intervals in the direction in which the pipe body 20 extends. Each section formed between the partition spacers 40 constitutes a detection space V.

[0027] Because the detection space V is formed between the partition spacers 40 in this way, sodium can be detected within the partitioned space, making it possible to detect sodium leaks with high accuracy. Furthermore, since the detection space V is divided into multiple sections, even if a leak occurs in one place, the area affected can be limited. As a result, the integrity of the piping system 2 can be further improved.

[0028] (Intake section 50) The intake section 50 is a porous tube positioned within the detection space V. In other words, the intake section 50 has numerous openings through which gas can flow. The intake section 50 has a first section 51 and a second section 52. The first section 51 and the second section 52 extend along the direction in which the main piping body 20 extends. A main line 60 through which gas flows is connected between the first section 51 and the second section 52. The first section 51 extends toward one side from the point to which the main line 60 is connected, and the second section 52 extends toward the other side from the point to which the main line 60 is connected. For example, the extended lengths of the first section 51 and the second section 52 are the same. Therefore, the main line 60 is connected to the central part of the extended length of the intake section 50. Note that these lengths may be different from each other. Openings are formed in both the first section 51 and the second section 52.

[0029] As described above, the intake section 50 is a porous tube. This allows for a uniform supply of gas to a wider area within the detection space V, and uniform extraction of gas from a wider area within the detection space V. Furthermore, the porous tube includes a first section 51 and a second section 52, and the main line 60 is connected between them. Therefore, the possibility of uneven pressure distribution in the gas flow drawn in and out from the first section 51 and the second section 52 through the main line 60 can be reduced. In other words, for example, if the main line 60 were connected only to the end of the porous tube, the gas pressure would decrease as it moved away from the end, potentially making smooth intake and exhaust difficult. In contrast, the above configuration reduces this possibility and enables smooth intake and exhaust of gas.

[0030] (Gas transport pump 70) The gas transport pump 70 is located on the main line 60 described above. The gas transport pump 70 can draw in and exhaust gas from the detection space V via the intake section 50. Various types of gas transport pumps can be used for the gas transport pump 70, such as scroll type, rotary type, or scroll-rotary type. In the case of a scroll type or rotary type gas transport pump 70, for example, by switching the direction of rotation between forward and reverse, it is possible to switch between drawing gas onto the main line 60 and exhausting gas from the main line 60.

[0031] (Detection unit 80) The detection unit 80 is a sensor or measuring instrument capable of detecting sodium contained in the gas flowing through the main line 60. A first valve 110 is positioned between the detection unit 80 and the intake unit 50 on the main line 60. The first valve 110 is an on / off valve that switches the flow state of the gas on the main line 60. The first valve 110 is, for example, an electromagnetic on / off valve. As will be described in more detail later, the open / closed state of the first valve 110 is controlled by an electrical signal transmitted from the control device 180.

[0032] (Inert gas supply line 90, gas supply source 100) The inert gas supply line 90 branches off from the main line 60 midway along its extension. A gas supply source 100 is connected to the end of the inert gas supply line 90. The gas supply source 100 stores nitrogen, for example, as an inert gas. The gas supply source 100 supplies inert gas to the intake section 50 through the inert gas supply line 90. A second valve 120 is provided on the inert gas supply line 90. The second valve 120 is an on / off valve that switches the flow state of the gas on the inert gas supply line 90. The second valve 120 is also an electromagnetic on / off valve, as an example. As will be described in more detail later, the open / closed state of the second valve 120 is controlled by an electrical signal transmitted from the control device 180.

[0033] (Enclosure 130) The enclosure 130 is a cylindrical member that covers the surrounding member 30 from the outer periphery. A space is formed between the inner surface of the enclosure 130 and the outer surface of the pipe body 20. This space is a capture space Z that captures leaked sodium to prevent the leakage of the leaked component to the outside when sodium leaks from the pipe body 20. The lower half of the enclosure 130 functions as a transfer path to guide the leaked sodium to the transfer line 160, which will be described later.

[0034] (Drain line 140) A drain line 140 is connected to the main body of the piping 20 midway along its extension, allowing the sodium inside the piping 20 to be discharged to the outside (drain tank 210). The drain line 140 extends through the surrounding member 30 and the enclosure 130. A third valve 150 is provided on the drain line 140. The third valve 150 is an on / off valve that switches the flow state of sodium on the drain line 140. The third valve 150 is, for example, an electromagnetic on / off valve. As will be described in more detail later, the open / closed state of the third valve 150 is controlled by an electrical signal transmitted from the control device 180.

[0035] (Transfer line 160) The transfer line 160 is a pipe that can discharge sodium that has leaked from the detection space V into the space inside the enclosure 130 to the outside (transfer tank 220). A fourth valve 170 is provided on the transfer line 160 as a transfer line valve. The fourth valve 170, like the third valve 150, is an electromagnetic valve that opens and closes in response to an electrical signal from the control device 180.

[0036] (Nitrogen concentration meter 200) The nitrogen concentration meter 200 is not an essential component of the present invention, but it is installed in the building where the piping system 2 is laid and is an instrument for measuring the nitrogen concentration inside the building.

[0037] (Control device 180) The control device 180 can switch the open / closed states of the first valve 110, the second valve 120, the third valve 150, and the fourth valve 170, as well as the operation of the gas transport pump 70, based on the detection results of the detection unit 80. As shown in Figure 3, the control device 180 has, as functional blocks, a detection result acquisition unit 181, a determination unit 182, a drive unit 183, and a storage unit 184.

[0038] The detection result acquisition unit 181 acquires the detection results from the detection unit 80 described above. The determination unit 182 determines whether or not sodium components are present in the gas in the detection space V based on the detection results acquired by the detection result acquisition unit 181. The drive unit 183 switches the open / closed state of the first valve 110, the second valve 120, the third valve 150, and the fourth valve 170, and the operating state of the gas transport pump 70, based on the determination result of the determination unit 182. Specifically, during normal operation of the fast reactor 1 (when no sodium leakage is detected), the drive unit 183 opens the first valve 110, closes the second valve 120, and operates the gas transport pump 70 to pump the gas in the detection space V towards the detection unit. The drive unit 183 also closes the first valve 110 and opens the second valve 120 when an abnormality occurs, such as when sodium is detected in the gas by the detection unit, and operates the gas transport pump 70 to supply inert gas 90 into the detection space V through the inert gas supply line 90. The storage unit 184 stores data such as tables and graphs that the determination unit 182 uses for determination.

[0039] Next, the processing flow of the control device 180 will be described with reference to Figure 4. Figure 4 is a flowchart showing the processing flow of the control device according to the first embodiment of the present invention. First, during normal operation of the piping system 2 (i.e., when no sodium leakage is detected), the drive unit 183 opens the first valve 110 and closes the second valve 120 (step S11). The drive unit 183 also switches the operating state of the gas transport pump 70 to a direction in which gas is drawn in (inhaled) from the intake unit 50 toward the detection unit 80 (step S12). As a result, the gas in the detection space V is pressurized and sent to the detection unit 80 through the main line 60. During this time, the detection result acquisition unit 181 intermittently or continuously acquires the electrical signal output by the detection unit 80 as a detection result. Furthermore, the drive unit 183 closes the third valve 150 and the fourth valve 170 (step S13). As a result, during normal operation, the drain line 140 and the transfer line 160 are closed. In Figure 4, steps S11 to S13 are shown as separate blocks, but the order in which the processing of each block is executed is arbitrary.

[0040] Next, the determination unit 182 determines whether or not sodium is present in the gas within the detection space V based on the detection result of the detection unit 80 (step S14). If it is determined in step S14 that sodium is not present (step S14-No), the process in step S14 is repeated.

[0041] On the other hand, if it is determined in step S14 that sodium is present (step S14-Yes), the drive unit 183 closes the first valve 110 and opens the second valve 120 (step S15). This connects the gas supply source 100 and the intake section 50. In this state, the drive unit 183 switches the operating state of the gas transport pump 70 so that gas flows (exhausts) from the gas supply source 100 towards the intake section 50 (step S16). As a result, the inert gas (nitrogen) stored in the gas supply source 100 is pressurized and sent into the detection space V through the intake section 50.

[0042] As described above, with this configuration, during normal operation, the control device 180 operates the gas transport pump 70 to pump the gas in the detection space V toward the detection unit 80. When sodium is detected in the gas by the detection unit 80, it can be determined that a leak has occurred. In other words, when an abnormality occurs in which sodium is detected in the gas, the operation of the gas transport pump 70 is switched, and inert gas is supplied into the detection space V through the inert gas supply line 90. This increases the concentration of inert gas in the air within the detection space V. Therefore, the possibility of sodium combustion occurring when sodium comes into contact with oxygen can be significantly reduced.

[0043] Next, in step S17, the drive unit 183 opens the third valve 150 and the fourth valve 170. As a result, the sodium in the piping body 20 is discharged to the outside through the drain line 140, and the sodium that has leaked into the capture space Z in the enclosure 130 is discharged to the outside through the transfer line 160.

[0044] In this embodiment, when an abnormality occurs, the control device 180 opens the third valve 150 and the fourth valve 170. As a result, the sodium in the piping body 20 is discharged to the outside through the drain line 140. Therefore, further leakage of sodium from the piping body 20 into the detection space V can be prevented. In addition, the sodium in the capture space Z is discharged to the outside through the transfer line 160. Therefore, the leaked sodium can be transferred to a storage unit more suitable for sodium storage (in this case, the transfer tank 220). As a result, even if sodium leakage occurs, sodium is less likely to remain in various places, thus greatly reducing the possibility of a sodium fire occurring.

[0045] Furthermore, with the above configuration, the control device 180 closes the third valve 150 and the fourth valve 170 during normal operation. That is, during normal operation, the drain line 140 and the transfer line 160 are closed. Therefore, the possibility of sodium unintentionally flowing out to the outside through the drain line 140 can be reduced. Also, because the transfer line 160 is closed, even if sodium leaks into the capture space Z, transfer will not start until the valve is opened. As a result, the leaked sodium can be contained in the capture space Z, and the area affected by the sodium leak can be limited to a small size. Consequently, the function of suppressing the expansion of the sodium leakage area in the piping system 2 can be further enhanced.

[0046] Furthermore, in the above configuration, the main line 60 and the gas transport pump 70 are used in common for both the extraction of gas from the detection space V and the supply of nitrogen to the detection space V. Therefore, the equipment configuration can be simplified. As a result, construction costs and operating costs can be reduced.

[0047] The first embodiment of the present invention has been described above. It is possible to make various changes and modifications to the above configuration and processing without departing from the spirit of the present invention.

[0048] <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to Figures 5 and 6. Figure 5 is a functional block diagram of the control device according to the second embodiment of the present invention. Figure 6 is a flowchart showing the processing flow of the control device according to the second embodiment of the present invention. Components similar to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0049] As shown in Figure 5, the configuration of the control device 180 in this embodiment differs from that of the first embodiment. Specifically, in addition to the functional blocks described in the first embodiment, the control device 180 further includes a leakage amount acquisition unit 185. The leakage amount acquisition unit 185 acquires the detection result regarding the liquid level height (liquid level) of the leaked sodium from the liquid level meter 190 provided in the capture space Z as an electrical signal.

[0050] The determination unit 182 compares the detection result obtained by the leakage amount acquisition unit 185 with a predetermined threshold. Specifically, the determination unit 182 uses the detection result obtained by the leakage amount acquisition unit 185 to determine whether the amount of sodium leaked into the space inside the enclosure 130 exceeds a predetermined threshold.

[0051] The drive unit 183 switches the open / closed states of the first valve 110, second valve 120, third valve 150, and fourth valve 170, as well as the operating state of the gas transport pump 70, based on the determination result of the determination unit 182. For example, if the drive unit 183 determines that the amount of sodium leaked into the space inside the enclosure 130 exceeds a predetermined threshold, it opens the fourth valve 170.

[0052] Next, the processing flow of the control device 180 will be described with reference to Figure 6. As shown in the figure, in the processing flow according to this embodiment, each process from step S11 to step S14 is the same as the processing flow of the first embodiment described above.

[0053] On the other hand, the processing after step S14 differs from that of the first embodiment. Specifically, if it is determined in step S14 that sodium leakage has occurred (step S14-Yes), the drive unit 183 first closes the first valve 110 and opens the second valve 120 (step S25). Subsequently, the drive unit 183 switches the operating state of the gas transport pump 70 so that inert gas (nitrogen) is pressurized and sent from the gas supply source 100 toward the intake section 50 (step S26).

[0054] In parallel with this, the determination unit 182 determines whether the leakage amount is greater than the threshold value based on the results obtained by the leakage amount acquisition unit 185 (step S27). If the result in step S27 is No, the drive unit 183 opens the third valve 150 (step S28). Then, step S27 is repeated. From this state, if the result in step S27 is Yes, the drive unit 183 opens the fourth valve 170 (step S29).

[0055] In this configuration, the control device 180 opens the fourth valve 170 when it determines that the amount of sodium leaked into the space inside the enclosure 130 exceeds a threshold. Conversely, if the amount of leakage is below the threshold, the fourth valve 170 remains closed. Therefore, if the amount of leakage is, for example, a small amount that does not require opening the transfer line 160, the fourth valve 170 of the transfer line 160 remains closed, and the small amount of leaked sodium is contained within the space inside the enclosure 130. This makes it possible to minimize the area affected by the sodium leak. As a result, the piping system 2 can be restored quickly.

[0056] The second embodiment of the present invention has been described above. It is possible to make various changes and modifications to the above-described configurations and processes without departing from the spirit of the present invention.

[0057] <Variation> For example, in the processing flow of the second embodiment described above, the control device 180 may be configured to keep the fourth valve 170 open during normal operation, close the fourth valve 170 when an abnormality occurs, and open the fourth valve 170 if it is determined that the amount of sodium leakage exceeds a predetermined threshold while the fourth valve 170 is closed.

[0058] In this configuration, the fourth valve 170 is in the open state during normal operation. This means that, for example, even if the fourth valve 170 cannot be closed for some reason in the event of an abnormality, since the fourth valve 170 is in the open state from the beginning, the leaked sodium can be discharged to the outside by the transfer line 160 without accumulating in the capture space Z. Therefore, the reliability of the piping system 2 can be further improved.

[0059] Furthermore, although the above embodiment described an example in which the piping system 2 is used for transferring secondary coolant, the application of the piping system 2 is not limited to this. As another example, it can also be applied to the piping of the primary cooling system. Moreover, the piping system 2 can be applied not only to the tank-type fast reactor 1 described above, but also to loop-type fast reactors. In either case, the same effects and advantages as described above can be obtained.

[0060] Furthermore, the arrangement and number of gas transport pumps 70 described above are just examples; as another example, it is also possible to adopt a configuration in which one gas transport pump 70 is placed on the main line 60 and one on the inert gas supply line 90.

[0061] In addition, the piping system 2 according to each of the above embodiments can be suitably used under either a nitrogen atmosphere or an air atmosphere. In either case, the same effects and advantages as described above can be obtained.

[0062] (effect) According to the above configuration, when an abnormality occurs and sodium is detected in the gas, the operation of the gas transport pump 70 is switched, and an inert gas such as nitrogen is supplied into the detection space V through the inert gas supply line 90. As a result, the concentration of the inert gas in the air within the detection space V increases. Therefore, a fire caused by the combustion of sodium can be effectively prevented.

[0063] According to the above configuration, when an abnormality occurs, the control device 180 opens the third valve 150 and the fourth valve 170. As a result, the sodium in the piping body 20 is discharged to the outside through the drain line 140. Therefore, further leakage of sodium from the piping body 20 can be prevented. In addition, the sodium in the detection space V is discharged to the outside through the transfer line 160. Therefore, the possibility of leaked sodium remaining in the detection space V can be reduced.

[0064] According to the above configuration, the control device 180 closes the third valve 150 and the fourth valve 170 during normal operation. That is, during normal operation, the drain line 140 and the transfer line 160 are closed. Therefore, the possibility of sodium leaking to the outside through the drain line 140 is reduced. In addition, because the transfer line 160 is closed, even if a leak occurs, transfer will not start until the valve is opened, thus limiting the area affected by the sodium leak.

[0065] According to the above configuration, the control device 180 opens the fourth valve 170 when it determines that the amount of sodium leaked into the space inside the enclosure 130 exceeds a threshold. Conversely, if the amount of leakage is below the threshold, the fourth valve 170 remains closed. Therefore, if the amount of leakage is, for example, a very small amount, the transfer line 160 remains closed, and the small amount of leaked sodium is confined to the space inside the enclosure 130. This makes it possible to minimize the area affected by the sodium leak.

[0066] According to the above configuration, the intake section 50 is a porous tube. That is, the intake section 50 has a large number of openings through which gas can flow. This makes it possible to supply gas evenly to a wider area within the detection space V, or to extract gas evenly from a wider area within the detection space V. Furthermore, the porous tube includes a first section 51 and a second section 52, and the main line 60 is connected between them. Therefore, it is possible to reduce the possibility of bias in the pressure distribution of the gas flow that is drawn in and exhausted from the first section 51 and the second section 52 through the main line 60.

[0067] According to the above configuration, detection spaces V are formed between partition spacers 40. By configuring detection spaces V between each partition spacer 40 in this way, it becomes possible to detect sodium leaks in detail within the partitioned areas. Furthermore, since the detection spaces V are divided into multiple sections, even if a leak occurs in one location, the area affected can be limited.

[0068] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combinations are combined with the effects of the original embodiments. [Explanation of Symbols]

[0069] 1...Fast reactor 2… Piping system 10…Reactor vessel 11… core 12…Intermediate heat exchanger 13…Coolant circulation pump 14…Furnace piping 15…Steam generator 20... Piping body 30... Encircling member 31…Interior panels 32…Heat insulation material 33…Exterior plate 40... Partition spacer 50... Intake section 51…Part 1 52…Second part 60... Main line 70... Gas transport pump 80...Detection unit 90...Inert gas supply line 100... Gas supply source 110...First valve 120...Second valve 130... Enclosure 140... Drain line 150...Third valve 160...Transfer line 170...Fourth valve 180...Control device 181...Detection result acquisition unit 182…Judgment section 183... Drive unit 184...Storage section 185... Leakage amount acquisition unit 190…Liquid level gauge 200... Nitrogen concentration meter 210... Drain tank 220...Transfer tank V...Detection space Z…Capturing space

Claims

1. The main body of the piping through which sodium flows, A surrounding member that covers the pipe body from the outer periphery to form a detection space on the inside, An intake section arranged within the aforementioned detection space, The main line connected to the intake section, A gas transport pump, positioned on the main line and capable of drawing in and exhausting gas from the detection space via the intake section, A detection unit for detecting sodium contained in the gas flowing through the main line, An inert gas supply line is provided branching off from the main line, A gas supply source that supplies inert gas through the aforementioned inert gas supply line, A first valve provided on the main line, A second valve provided on the aforementioned inert gas supply line, A control device capable of switching the open / closed state of the first valve and the second valve and the operation of the gas transport pump based on the detection result of the detection unit, Equipped with, The control device is During normal operation, the first valve is opened, the second valve is closed, and the gas transport pump is operated to pressurize the gas in the detection space toward the detection unit. A piping system for a fast reactor in which, when an abnormality occurs in which sodium is detected in the gas by the detection unit, the first valve is closed, the second valve is opened, and the gas transport pump is operated to supply inert gas to the detection space through the inert gas supply line.

2. An enclosure that covers the aforementioned surrounding member from the outer periphery, A drain line that can discharge sodium from the piping body to the outside, A third valve provided on the drain line, A transfer line capable of discharging sodium that has leaked from the detection space into the space inside the enclosure to the outside, A fourth valve provided on the transfer line, Furthermore, The piping system for a fast reactor according to claim 1, wherein the control device opens the third valve and the fourth valve when the abnormality occurs.

3. The piping system for a fast reactor according to claim 2, wherein the control device keeps the third valve and the fourth valve closed during normal operation.

4. An enclosure that covers the aforementioned surrounding member from the outer periphery, A transfer line capable of discharging sodium that has leaked from the detection space into the space inside the enclosure to the outside, A fourth valve provided on the transfer line, Furthermore, The piping system for a fast reactor according to claim 1, wherein the control device determines that the amount of sodium leaked into the space within the enclosure exceeds a predetermined threshold, and sets the fourth valve to an open state.

5. An enclosure that covers the aforementioned surrounding member from the outer periphery, A transfer line capable of discharging sodium that has leaked from the detection space into the space inside the enclosure to the outside, A fourth valve provided on the transfer line, Furthermore, The piping system for a fast reactor according to claim 1, wherein the control device keeps the fourth valve open during normal operation, closes the fourth valve when an abnormality occurs, and opens the fourth valve when it is determined that the amount of sodium leaked into the space inside the enclosure exceeds a predetermined threshold while the fourth valve is closed.

6. The intake section is a porous tube that extends along the main body of the piping and has a number of openings through which the gas in the detection space can flow, and the porous tube includes a first portion that extends toward one side from the portion to which the main line is connected and a second portion that extends toward the other side, and the openings are formed in both the first portion and the second portion, according to any one of claims 1 to 5.

7. The pipe body and the surrounding member further comprise a plurality of partition spacers arranged to surround the pipe body, The piping system for a fast reactor according to any one of claims 1 to 5, wherein the detection space is formed between the plurality of partition spacers.

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