Natural circulation SMR nuclear reactor and heat exchange method of same

Abstract

In a natural circulation SMR nuclear reactor according to one embodiment of the present invention, an inner plate heat exchanger having an elongated plate shape is compactly connected to the inside of a nuclear reactor vessel in the vertical direction in an integral or assembled manner in place of a conventional independent helical steam generator, an outer plate heat exchanger is compactly connected to the outside of the nuclear reactor vessel in the vertical direction in an integral or assembled manner, and an outer steam generator containing the outer plate heat exchanger is installed on the outer periphery of the nuclear reactor vessel, thereby facilitating internal flow. Thus, the need to drill holes for supplying water to and discharging steam from the steam generator into the nuclear reactor vessel may be reduced.

Description

Natural circulation type SMR reactor and heat exchange method thereof

[0001] The present invention relates to a natural circulation type SMR reactor and a heat exchange method thereof, and more particularly, to a natural circulation type SMR reactor and a heat exchange method thereof in which a steam generator is removed from the inside and a plate heat exchanger is modularly installed inside and outside the reactor vessel to fit the flow path to optimize internal flow.

[0002] Among the main design concepts and characteristics of SMRs (small modular reactors) being developed domestically and internationally, when categorized into forced circulation and natural circulation types of coolant, the natural circulation types include NuScale, IRIS, CAREM, mPower, and KEPCO E&C's Bandi, which have enhanced their inherent safety by utilizing the natural circulation principle.

[0003] In the case of forced circulation type, a flow skirt is installed at the bottom of the core to form a flow so that the coolant flowing into the core is distributed horizontally and evenly, but in the case of natural circulation type SMR, the internal flow method is not known.

[0004] Looking at the NuScale-based SMR startup procedure, it consists of activating the heating system (increasing the temperature of the internal working fluid) → removing heat from the coolant by the heat sink (steam generator) → monitoring the coolant temperature → deactivating the heating system → increasing the reactor power to reach the critical point → reactivating the heating system (thereafter, it only participates in maintaining the pressure inside the reactor).

[0005] In the SMR startup procedure, the “Stable Startup System” is important, and most natural circulation SMRs implement a similar system for initial startup.

[0006] The biggest challenge here is that, like forced circulation SMRs, a flow skirt cannot be installed. Furthermore, the flow skirt is controlled by the hole size, requiring additional complex design features.

[0007] And basically, the steam generator (tube type, large commercial furnace has 12,000 to 14,000, SMR has about 5,000 tubes with an inner diameter of 12 mm) is installed inside the SMR, which has a very significant impact (resistance and interference) on the internal flow.

[0008] A powerful RCP (coolant pump) is required for the flow inside the SMR, which limits the compact configuration of the inside and outside of the SMR.

[0009] In addition, as illustrated in Fig. 1, the coolant heated in the core (12) is configured to exchange heat with the steam generator (13) placed in the middle region of the SMR reactor vessel (11) when it rises due to buoyancy and flows upward and falls down toward the side like a waterfall.

[0010] A typical steam generator (13) is helical in shape to obtain the maximum heat exchange cross-sectional area in a narrow space, and a water supply pipe (13a) and a steam pipe (13b) are arranged at the top and bottom so that water is supplied through the water supply pipe (13a), and steam generated after heat exchange through the helical tube is configured to be transferred to the turbine through the steam pipe (13b).

[0011] The problem with this structure is that if the tube of the steam generator (13) inside the SMR reactor (10) is cracked or has a hole, the radioactive coolant inside the SMR reactor (10) leaks out (to the secondary side).

[0012] This is called SGTR (Steam Generator Tube Rupture), and this is not a big problem for large commercial reactors because they have strong RCP (main feedwater pump) and use serial tube type steam generators rather than helical ones, but SMR reactors have the problem that their internal structure is compact, making it difficult to configure them as a natural circulation type, and there is the problem that the helical tubes must be manufactured very strongly.

[0013] In addition, in an SMR reactor, usually 6 to 8 steam generators (13) are tightly packed around the inner periphery of the reactor vessel (11). In this case, the feed water pipes (13a) and steam pipes (13b) must form a total of 12 to 16 holes in the outer wall of the SMR reactor vessel (11), so there is a problem that the probability of the tubes of the steam generators (13) cracking or forming holes increases.

[0014] The present invention has been devised to solve these problems, and the purpose of the present invention is to provide a small modular reactor with optimized internal flow that can prevent major accidents such as tube ruptures by optimizing the internal flow path of an SMR to increase the flow rate, simplify the internal structure of an SMR, and simplify the external appearance of an SMR, and eliminate the need for tube clogging and maintenance of a steam generator.

[0015] A natural circulation SMR reactor with optimized internal flow according to one embodiment of the present invention is characterized by including: a reactor vessel; an outer steam generator installed outside the reactor vessel and installed above the core inside the reactor vessel; an inner plate heat exchanger installed along the inner periphery of the reactor vessel above the core inside the reactor vessel; and an outer plate heat exchanger to which heat is transferred from the inner plate heat exchanger and installed inside the outer steam generator.

[0016] According to a small modular reactor with optimized internal flow according to one embodiment of the present invention, by optimizing the internal flow path of the SMR, the flow rate can be increased, the internal structure of the SMR can be simplified, and the external appearance of the SMR can be simplified, thereby preventing major accidents such as tube rupture and eliminating the need for tube clogging and maintenance of the steam generator.

[0017] Figure 1 is a cross-sectional view of a typical SMR reactor;

[0018] Figure 2 is a cross-sectional view of an SMR reactor according to one embodiment of the present invention, and

[0019] Figure 3 is a configuration diagram of a steam generator for an SMR reactor according to one embodiment of the present invention.

[0020] The present invention will be described in more detail with reference to the drawings below.

[0021] The attached drawings are merely examples provided to more specifically explain the technical idea of ​​the present invention, and therefore the idea of ​​the present invention is not limited to the attached drawings.

[0022] Additionally, the attached drawings may be exaggerated in size and spacing to illustrate the relationship between each component.

[0023] As illustrated in FIGS. 1 and 2, an SMR reactor (10) according to one embodiment of the present invention is configured to include a reactor vessel (11), a core (12), a plate heat exchanger (13), a reactor coolant pump (14), a pressurizer (15), a core support barrel (17), a control rod drive device (18), and a bulkhead vessel (19) on the outer periphery of the reactor vessel (11).

[0024] The reactor vessel (11) can form the exterior of the SMR reactor (10).

[0025] The reactor vessel (11) may be a pressure vessel made of carbon steel to load nuclear fuel and allow a chain nuclear fission reaction to occur safely.

[0026] The reactor vessel (11) may be composed of an upper vessel body (11a), a lower vessel body (11b), and a reactor head (11c).

[0027] The upper container body (11a) may be formed in a cylindrical shape. The upper container body (11a) may be formed to be open in the vertical direction.

[0028] The upper container body (11a) may have a receiving space in which an inner plate-type heat exchanger (135) is placed in an integrated or detachable form.

[0029] The lower vessel body (11b) may be formed in a cylindrical shape. The reactor vessel (11) may be formed to have a vertical length longer than its diameter.

[0030] A hemispherical lower head can be mounted on the lower part of the lower container body (11b).

[0031] The reactor head (11c) may be connected to a flange using stud bolts to cover the upper portion of the upper vessel body (11a). A control rod drive device (18) may be mounted on the outside of the reactor head (11c) for inserting or withdrawing control rods that control the nuclear fission reaction rate.

[0032] The primary system is a system that cools the core (12) by directly transferring heat from the core (12) by circulating the reactor coolant, which is the primary system fluid. The primary system includes an inner plate heat exchanger (135), a reactor coolant pump (14), a pressurizer (15), etc.

[0033] A secondary system is a system that maintains a pressure boundary with the primary system and generates electricity using heat transferred from the primary system. The secondary system is equipped with a turbine and a generator, which generates electricity.

[0034] The core (12) is placed at the bottom of the reactor vessel (11). The core (11) is where nuclear fuel is loaded and may be composed of a nuclear fuel assembly.

[0035] Inside the reactor vessel (11), a core support barrel (17), which is an internal structure that can be separated from each other, can be installed.

[0036] The core support barrel (17) is designed to support the nuclear fuel from below.

[0037] The interior of the reactor vessel (11) is filled with a primary system fluid, and the heat received from the core (12) is transferred to the secondary system fluid of the steam generator (131) located inside the outer plate heat exchanger (137) connected to the inner plate heat exchanger (135) through a connection (133).

[0038] A plurality of nozzles are formed to penetrate the reactor vessel (11) in the thickness direction. An inner plate heat exchanger (135) and a reactor coolant pump (14) can be connected to the plurality of nozzles.

[0039] The reactor coolant pump (14) can be installed on the upper part of the inner plate heat exchanger (135).

[0040] The impeller of the reactor coolant pump (14) is connected to the electric motor via a rotating shaft. As the electric motor operates, the impeller rotates to circulate the reactor coolant.

[0041] The inner plate heat exchanger (135) may be located on the upper part of the core (12). The inner plate heat exchanger (135) may be located higher than the core (12), and a plurality of inner plate heat exchangers (135) may be installed spaced apart from each other in the circumferential direction on the inner part of the reactor vessel (11).

[0042] The outer plate heat exchanger (137) can be installed in multiple numbers spaced apart from each other in the circumferential direction on the outer periphery of the reactor vessel (11) in response to the inner plate heat exchanger (135).

[0043] It is preferable that the outer plate heat exchanger (137) be connected to the inner plate heat exchanger (135) by a connecting portion (133) made of a material with good thermal conductivity, and the outer plate heat exchanger (137) can be installed inside a cylindrical steam generator (131) installed on the outer periphery of the reactor vessel (11).

[0044] The circulation path can be formed to make thermal contact with the inner plate heat exchanger (135) through the core support barrel (17) and the upper guide structure in the core (12), and to be connected to the inner plate heat exchanger (135) through a connection portion (133) and to exchange heat with the outer plate heat exchanger (137) arranged inside the steam generator (131).

[0045] The reactor coolant rises along the circulation path in the core (12), and can flow into the upper part while contacting the inner side of the inner plate heat exchanger (135) and transferring heat.

[0046] According to this configuration, the reactor coolant of the primary system circulates in the order of the core (12), the reactor coolant pump, the inner plate heat exchanger (135), and the core (12), and the heat generated in the core (12) can be transferred to the steam generator (131) outside the reactor vessel (11) through the inner plate heat exchanger (135).

[0047] The inner plate heat exchanger (135) or the outer plate heat exchanger (137) is configured in a fin shape, and the reactor coolant moves upward while only contacting the inner side of the inner plate heat exchanger (135), and at this time, the heat of the inner plate heat exchanger (135) is transferred to the outer plate heat exchanger (137) through the connection part (133) so that heat can be exchanged with the outside.

[0048] The lower part of the steam generator (131) outside the reactor vessel (11) is connected to the feed water system through a feed water pipe (131a) and receives water from the feed water system.

[0049] A water supply valve is installed in the water supply pipe (131a), so that the water supply pipe (131a) can be opened and closed.

[0050] The upper part of the steam generator (131) is connected to the turbine system, and the steam generated in the plate heat exchanger (13) of the steam generator (131) is supplied to the turbine system through the steam pipe (13b).

[0051] Likewise, a steam valve is installed in the steam pipe (131b) so that the steam pipe (131b) can be opened and closed.

[0052] In the case of an SMR reactor, when feedwater is supplied to the steam generator (131) from the feedwater system through the feedwater pipe (131a) during normal operation, the inner plate heat exchanger (135) heat-exchanges the heat transferred from the core (12) to the outer plate heat exchanger (137), and the steam generated at this time is supplied to the turbine system through the steam pipe (131b), and the turbine system uses the supplied steam to produce electricity.

[0053] As illustrated in FIG. 3, a natural circulation small modular reactor (10) with optimized internal flow according to one embodiment of the present invention is characterized in that a steam generator (131) is installed in close contact with the outside of a reactor vessel (11) in a tubular shape having a coolant storage space (131a).

[0054] It is preferable that the shape of the steam generator (131) has a shape corresponding to the outer circumference of the reactor vessel (11) and has a reactor vessel-compatible coupling surface (131b) that is easy to tightly couple.

[0055] The outer plate heat exchanger (137) installed inside the steam generator (131) and the inner plate heat exchanger (135) installed longitudinally inside the reactor vessel (11) are composed of thin and long metal rods in the form of a kind of fin, and can be installed spaced apart from each other from top to bottom and along the circumferential direction of the reactor vessel (11).

[0056] The inner plate heat exchanger (135) and the outer plate heat exchanger (137) are preferably made of a metal material having good thermal conductivity, and a plurality of them may be formed by welding and spaced apart in the circumferential direction inside and outside the reactor vessel (11), or may be joined by a fastening means.

[0057] The above inner plate heat exchanger (135) can serve as a flow path (guide) through which coolant flows during circulation operation in which coolant that rises from the center of the reactor (10) through heat exchange in the core (12) of the SMR reactor (10) descends to the outer part of the reactor.

[0058] In a conventional SMR reactor, the principle is that the cooling water enters the steam generator, exchanges heat, and comes out, but in the SMR reactor according to one embodiment of the present invention, the cooling water in the reactor (10) can only circulate in the reactor, and the cooling water in the reactor (10) is thermally connected to the inner plate heat exchanger (135) inside the reactor and the outer plate heat exchanger (137) installed outside the reactor by a plate-shaped connecting portion (133), and the outer plate heat exchanger (137) can be installed so as to exchange heat with the cooling water that flows in through the feed water pipe (131a) inside the steam generator (131) installed outside the reactor vessel (11).

[0059] The coolant, whose temperature has risen in the core (12) of the SMR reactor (10), transfers heat to the outer plate heat exchanger (137) through the inner plate heat exchanger (135), then descends to the lower part of the core (12) and then rises back to the core (12) from the lower head, performing a circulatory operation.

[0060] In a natural circulation type SMR reactor (10) according to one embodiment of the present invention, since a conventional independent helical steam generator (13) is not installed inside the reactor vessel (11), there is no need to drill a hole in the outer wall of the reactor vessel (11) to connect a feed water pipe (13a) and a steam pipe (13b) for a conventional independent helical steam generator (13), thereby solving the problem of cracking or breaking the structure.

[0061] According to one embodiment of the present invention, a natural circulation type SMR reactor (10) can facilitate internal flow by connecting a long plate-shaped inner plate heat exchanger (135) in place of a conventional independent helical steam generator (13) in an integral or assembled manner to the inside of a reactor vessel (11) in a vertical direction in a dense manner, connecting an outer plate heat exchanger (137) in an integral or assembled manner to the outside of the reactor vessel (11) in a vertical direction in a dense manner, and installing an outer steam generator (131) containing the outer plate heat exchanger (137) on the outer periphery of the reactor vessel (11).

[0062] In addition, the natural circulation type SMR reactor (10) according to one embodiment of the present invention is easy to install because the outer steam generator (131) can surround the outer periphery of the reactor vessel (11) and be joined by welding or a fastening means, and compared to the existing individual steam generator (13) installed outside the reactor, the cooling water inside the reactor does not circulate, but heat is transferred only by the inner or outer plate heat exchanger (135, 137) inside and outside the reactor, so there is no concern that the radioactive coolant inside the SMR reactor (10) will leak outside the SMR reactor (10) when the outer steam generator (131) is replaced.

[0063] According to a small modular reactor with optimized internal flow according to one embodiment of the present invention, by optimizing the internal flow path of the SMR, the flow rate can be increased, the internal structure of the SMR can be simplified, and the external appearance of the SMR can be simplified, thereby preventing major accidents such as tube rupture and eliminating the need for tube clogging and maintenance of the steam generator.

Claims

1. In a natural circulation type SMR reactor with optimized internal flow, reactor vessel; An outer steam generator installed outside the reactor vessel, but installed on the upper part of the core inside the reactor vessel; An inner plate heat exchanger installed along the inner periphery of the reactor vessel on the upper part of the core inside the reactor vessel; and A natural circulation type SMR reactor including an outer plate type heat exchanger installed inside the outer steam generator and in which heat is transferred from the inner plate type heat exchanger.

2. In paragraph 1, A natural circulation type SMR reactor in which the inner plate type heat exchanger and the outer plate type heat exchanger are formed of a plurality of fin shapes and are installed integrally or as an assembly on the inside and outside of the reactor vessel.

3. In paragraph 2, A natural circulation type SMR reactor in which the inner plate heat exchanger and the outer plate heat exchanger are made of a metal material having excellent thermal conductivity, the inner plate heat exchanger and the outer plate heat exchanger are in a vertically elongated plate shape, and the inner plate heat exchanger and the outer plate heat exchanger have a heat conductive connection that is connected in a horizontal direction.

4. In paragraph 1, A natural circulation type SMR reactor in which the outer steam generator is formed as a body having a corresponding joining surface having a shape corresponding to the shape of the outer wall of the reactor vessel, and a feed water pipe and a steam pipe are formed in the outer steam generator.

5. In paragraph 1, The above inner plate heat exchanger is a natural circulation type SMR reactor that forms a descending guide path for cooling water rising through the core inside the reactor vessel.

6. A heat exchange method of a natural circulation type SMR reactor, wherein the cooling water inside the reactor vessel circulates only inside the reactor vessel, and when the cooling water inside the reactor is heated by the core, the cooling water rises and transfers heat to a plurality of vertical inner plate heat exchangers spaced apart from each other in a circumferential direction on the inner periphery of the reactor vessel, the inner plate heat exchangers are thermally connected and transfer heat to a plurality of vertical outer plate heat exchangers spaced apart from each other in a circumferential direction on the outer periphery of the reactor vessel, and the outer plate heat exchanger is installed inside and heat exchange is performed in an outer steam generator installed outside the reactor vessel.

7. In paragraph 6, A heat exchange method for a natural circulation type SMR reactor, wherein heat is transferred from the inner plate heat exchanger to the outer plate heat exchanger through a thermal connection within the outer steam generator, and a water supply pipe for supplying water to the outer steam generator and a steam pipe for discharging steam generated by heat exchange with the outer plate heat exchanger are formed.

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