Passive containment cooling system for boiling water reactors and method of installation thereof

Abstract

The boiling water nuclear reactor includes a reactor building, a reactor cavity pool, a primary containment vessel, and a passive containment cooling system. The reactor building includes a top wall, a bottom wall, and at least one side wall with penetrations therein, which form a chamber. At least a portion of the primary containment vessel is within the chamber. The passive containment cooling system includes heat exchange piping including an outer pipe and an inner pipe. The outer pipe has a first outer pipe end and a second outer pipe end. The first outer pipe end is closed and is within the primary containment vessel. The second outer pipe end is open and extends into the reactor cavity pool. The inner pipe has a first inner pipe end and a second inner pipe end, which are open. The second inner pipe end extends from the outer pipe into the reactor cavity pool.

Description

[Technical field]

[0001] SUMMARY This disclosure relates to passive containment cooling systems for boiling water nuclear reactors. [Background technology]

[0002] After the reactor is shut down, the by-products of the nuclear reaction continue to undergo radioactive decay and generate heat. The decay heat from the by-products of the nuclear reaction is removed to limit and / or prevent damage to the nuclear fuel. If the reactor has a containment system, the decay heat can be removed from the containment system to limit and / or prevent overpressurization and damage to the containment system. In nuclear power plants with passive safety features, this decay heat can be removed by natural convection, conduction, and radiative heat transfer without the impediment of forced flow or electrical power.

[0003] Some reactor designs include a passive containment cooling system (PCCS) to remove reactor decay heat from the containment system. The PCCS system may include a PCCS condenser capable of condensing steam generated in the event of a core cooling failure or leak. The PCCS condenser contains channels (e.g., tubes and / or parallel plates) that transfer the heat to a pool outside the containment vessel where it can be vented to the atmosphere as water vapor or directly to the atmosphere.

[0004] In an accident scenario, the reactor may be depressurized to the containment system. In nuclear power plants with PCCS, depressurization from the reactor to the containment system may force non-condensable gases, such as steam and nitrogen, into the primary containment. After reactor depressurization, the steam condenses outside the PCCS condenser and is mostly steam and may contain traces of non-condensable gases (e.g., hydrogen, oxygen, nitrogen). Summary of the Invention [Means for solving the problem]

[0005] Some example embodiments relate to a boiling water nuclear reactor including a reactor building, a reactor cavity pool, a primary containment vessel, and a passive containment cooling system (PCCS). The reactor building includes a top wall portion forming a penetration therein, a bottom wall portion, and at least one side wall portion. The top wall portion, the bottom wall portion, and the at least one side wall portion form a chamber. The reactor cavity pool is adjacent to the reactor building. At least a portion of the primary containment vessel is within the reactor building chamber. The passive containment cooling system is configured to receive water and discharge hot water. The passive containment cooling system includes a heat exchange pipe. The heat exchange pipe includes an outer pipe having a first outer pipe end and a second outer pipe end. The first outer pipe end is closed and the second outer pipe end is open. The first outer pipe end is within the primary containment vessel. The second outer pipe end extends through a penetration in the top wall of the reactor building and into the reactor cavity pool such that the outer pipe is in fluid communication with the primary containment vessel and the reactor cavity pool. The heat exchange pipe further includes an inner pipe at least partially within the outer pipe. The inner pipe has a first inner pipe end and a second inner pipe end. The first inner pipe end and the second inner pipe end are open. The second inner pipe end extends from the outer pipe into the reactor cavity pool such that the second inner pipe end is in fluid communication with the reactor cavity pool.

[0006] In at least one exemplary embodiment, the outer pipe is comprised of a pipe wall defining an opening, and the inner pipe is comprised of a portion between a first inner pipe end and a second inner pipe end, the portion extending through the opening in the side of the pipe wall.

[0007] In at least one exemplary embodiment, the outer pipe has a diameter between 200 mm and 520 mm. The inner pipe has a diameter between 50 mm and 200 mm. The inner and outer pipes are made of stainless steel or a suitable material for pressure holding and corrosion resistance.

[0008] In at least one exemplary embodiment, the boiling water nuclear reactor further comprises at least one seal about the outer pipe adjacent a penetration in the top wall of the reactor building.

[0009] In at least one exemplary embodiment, the passive containment cooling system includes a plurality of heat exchange pipes. The passive containment cooling system includes between 2 and 20 heat exchange pipes.

[0010] In at least one exemplary embodiment, the boiling water nuclear reactor further comprises at least one support within the primary containment vessel, the at least one support configured to support a first end of an outer pipe of the heat exchange pipe, the at least one support comprising a spring support configured to accommodate up and down movement of the heat exchange pipe caused by expansion due to absorption of heat.

[0011] In at least one exemplary embodiment, the passive containment cooling system is valve-free, pump-free, or both valve-free and pump-free.

[0012] At least one exemplary embodiment relates to a passive containment cooling system.

[0013] In at least one exemplary embodiment, a passive containment cooling system includes a heat exchange pipe. The heat exchange pipe includes an outer pipe and an inner pipe. The outer pipe has a first outer pipe end and a second outer pipe end. The first outer pipe end is closed and the second outer pipe end is open. The first outer pipe end is within a primary containment vessel of a boiling water nuclear reactor. The second outer pipe end extends into the reactor cavity pool such that the outer pipe is in fluid communication with the primary containment vessel and the reactor cavity pool. The inner pipe is at least partially within the outer pipe. The inner pipe has a first inner pipe end and a second inner pipe end. The first inner pipe end and the second inner pipe end are open. The second inner pipe end extends from the outer pipe into the reactor cavity pool such that the second inner pipe end is in fluid communication with the reactor cavity pool.

[0014] In at least one exemplary embodiment, the outer pipe is constructed with a pipe wall defining an opening. The inner pipe includes a bend between a first inner pipe end and a second inner pipe end. The bend extends through the opening in the pipe wall. The outer pipe has a diameter between 200 mm and 520 mm. The inner pipe has a diameter between 50 mm and 200 mm. The inner and outer pipes are made of stainless steel.

[0015] At least one example embodiment relates to a method of installing a passive containment cooling system that includes positioning a heat exchange pipe at least partially within a primary containment vessel such that a portion of the heat exchange pipe extends into a reactor cavity pool. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram illustrating a boiling water nuclear reactor including a passive containment cooling system in accordance with at least one example embodiment. [Diagram 2]FIG. 2 is a perspective cross-sectional view of the boiling water nuclear reactor of FIG. 1 in accordance with at least one example embodiment. [Diagram 3] FIG. 3 is a side cross-sectional view illustrating a heat exchange pipe of the passive containment cooling system of FIGS. 1 and 2 according to at least one example embodiment. [Figure 4] FIG. 4 illustrates a top view of a portion of the boiling water nuclear reactor of FIG. 1 in accordance with at least one example embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Various elements and advantages of the non-limiting embodiments herein will become more apparent upon consideration of the detailed description in conjunction with the accompanying drawings. The accompanying drawings are provided for illustrative purposes only and should not be construed as limiting the scope of the claims. The accompanying drawings are not to be considered as drawn to scale unless expressly stated. Various dimensions of the drawings may be exaggerated for clarity.

[0018] Hereinafter, exemplary embodiments will be described more completely with reference to the accompanying drawings showing several exemplary embodiments. However, exemplary embodiments can be embodied in many different forms and should not be construed as being limited to the embodiments described herein, but rather, these exemplary embodiments are provided so that this disclosure will be comprehensive and complete, and will fully convey the scope of the exemplary embodiments to those skilled in the art. In the drawings, similar reference numerals in the drawings indicate similar elements, and therefore the description thereof may be omitted.

[0019] When an element or layer is referred to as "on," "connected to," "coupled to," or "covering" another element or layer, it should be understood that it may be directly on, directly connected to, or covering the other element or layer, or that intervening elements or layers may be present. On the other hand, when an element is referred to as "directly on," "directly connected to," or "directly coupled to," another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout the specification. As used herein, the term "and / or" includes any and all combinations of one or more of the items in the associated list.

[0020] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, but it should be understood that these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another region, layer, or section. Thus, a first element, component, region, layer, or section described below can be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0021] For ease of description, spatially relative terms (e.g., "beneath," "below," "lower," "above," "upper," etc.) may be used herein to describe the relationship of an element or feature to one or more other elements or features as shown. It should be understood that the spatially relative terms are intended to encompass various orientations of the device during use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "below" or "beneath" the other elements or features would be oriented "above" the other elements or features. Thus, the term "below" can encompass both an orientation above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0022] The terminology used herein is for the purpose of describing various embodiments only and is not intended to limit the illustrated embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "includes," "including," "comprises," and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0023] Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of exemplary embodiments. As such, variations from the shapes of the illustrations are to be expected as a result, for example, of manufacturing techniques and / or tolerances. As such, the illustrated embodiments should not be construed as limited to the shapes of regions illustrated herein but rather to encompass deviations in shapes that result, for example, from manufacturing. Thus, the regions illustrated in the drawings are schematic in nature and the shapes are not intended to represent the actual shapes of regions of a device and are not intended to limit the scope of the illustrated embodiments.

[0024] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which the illustrated embodiment belongs. Furthermore, terms, including those defined in commonly used dictionaries, should be interpreted in a manner consistent with the meaning in the context of the relevant technology, and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0025] It should also be noted that in some alternative implementations, the noted functions / acts may occur out of the order noted in the figures or described in the specification. For example, two figures or steps shown in succession may in fact be executed substantially simultaneously or may sometimes be executed in the reverse order or repeated, depending on the functions / acts involved.

[0026] FIG. 1 is a schematic diagram illustrating a boiling water nuclear reactor including a passive containment cooling system in accordance with at least one example embodiment.

[0027] 1, in at least one exemplary embodiment, boiling water reactor 100 may be a BWRX-300 reactor and may have the components and characteristics of a BWRX-300 reactor, although it is understood that the components described herein may be used in other plant configurations.

[0028] 1, a nuclear reactor 100 may include a reactor building 110, a primary containment vessel 120, a reactor cavity pool 130, and a passive containment cooling system (PCCS) 140. In at least one exemplary embodiment, the primary containment vessel 120 is housed within a chamber in the reactor building 110. The reactor cavity pool 130 is a water-filled tank used to cool hot water from the passive containment cooling system during an accident and / or during use. The reactor cavity pool 130 may sit above the reactor building 110 and the primary containment vessel 120, which is at least partially within the reactor building 110.

[0029] In at least one exemplary embodiment, the boiling water nuclear reactor 100 further comprises a core including fuel, channels, control rods, and instrumentation, a core support structure including a shroud, a shroud support, a top guide, a core plate, control rod guide tubes, and orificed fuel supports, a chimney, a steam dryer assembly, a feedwater sparger, and in-core guide tubes (not shown).

[0030] In at least one exemplary embodiment, the PCCS 140 includes at least one heat exchange pipe 150. The heat exchange pipe 150 extends from a chamber in the primary containment vessel, through a wall of the primary containment vessel, through a wall of the reactor building 110, and into the reactor cavity pool 130.

[0031] In at least one exemplary embodiment, the PCCS 140 is configured such that water from the reactor cavity pool 130 enters the primary containment vessel 120 through the heat exchange pipes 150. As the heat exchange pipes 150 absorb heat, the water heats up and becomes hot water, which is released through a path in the heat exchange pipes 150 due to density differences. The hot water that leaves the heat exchange pipes 150 enters the reactor cavity pool 130, mixes with the reactor cavity pool water, and is cooled by evaporation. The PCCS 140 does not include valves or pumps, and relies on gravity to deliver water from the reactor cavity pool 130 to the primary containment vessel 120. The cooling process of the PCCS 140 is a continuous process, and the water circulates naturally without any forced action.

[0032] FIG. 2 is a perspective cross-sectional view of the boiling water nuclear reactor of FIG. 1 in accordance with at least one example embodiment.

[0033] As shown in FIG. 2, in at least one exemplary embodiment, the boiling water reactor 100 is similar to FIG. 1, but is shown in more detail. As shown in FIG. 2, the reactor building 110 includes a top wall portion 200, a bottom wall portion 210, and at least one side wall portion 220. The reactor building 110 is formed of concrete. The top wall portion 200, the bottom wall portion 210, and the at least one side wall portion 220 form a chamber 230 that houses the primary containment vessel 120. The top wall portion 220 of the reactor building 110 may form a penetration 240 therein. The heat exchange pipes 150 extend through the penetrations 240. As shown, the boiling water reactor 100 includes a plurality of heat exchange pipes 150 and a plurality of penetrations 240. Each heat exchange pipe 150 extends through a corresponding one or more penetrations 240 into the reactor cavity pool 130.

[0034] In at least one exemplary embodiment, primary containment vessel 120 defines at least one passageway 250 in a wall thereof. Each of heat exchange pipes 150 extends into primary containment vessel 120 through a corresponding one of the at least one passageway 250.

[0035] FIG. 3 is a side cross-sectional view illustrating a heat exchange pipe of the passive containment cooling system of FIGS. 1 and 2 according to at least one example embodiment.

[0036] 3, in at least one exemplary embodiment, each of the heat exchange pipes 150 of the PCCS 140 includes an outer pipe 300 having a first outer pipe end 310 and a second outer pipe end 320. The first outer pipe end 310 is a closed end disposed within the primary containment vessel 120. The second outer pipe end 320 is an open end having an outlet 325 disposed within the reactor cavity pool 130. The outlet 325 is configured to release hot water into the reactor cavity pool 130.

[0037] In at least one exemplary embodiment, the second outer pipe end 320 may be angled. In some exemplary embodiments, the second outer pipe end 320 has an angle "A" of about 10° to about 80° (e.g., about 20° to about 70°, about 30° to about 60°, or about 40° to about 50°). For example, the angle "A" may be 45°. The outer pipe 300 may have a diameter of about 200 mm to about 520 mm (e.g., about 250 mm to about 350 mm). The outer pipe 300 may have a length of about 5,000 mm to about 25,000 mm (e.g., about 10,000 mm to about 20,000 mm).

[0038] In at least one exemplary embodiment, the heat exchange pipe 150 includes an inner pipe 330 having a first inner pipe end 340 and a second inner pipe end 360. The first inner pipe end 340 includes an outlet 365 and the second inner pipe end 360 includes an inlet 370, providing fluid communication between the inner pipe 330, the reactor cavity pool 130, and an inner portion of the outer pipe 300. Water from the reactor cavity pool 130 enters the inner pipe 330 via the inlet 370 and exits into the outer pipe 300 via the outlet 365. In at least one exemplary embodiment, the inner pipe 330 is at least partially contained within the outer pipe 300.

[0039] In at least one exemplary embodiment, the inner pipe 330 has a diameter of about 50 mm to about 200 mm (e.g., about 100 mm to about 175 mm, or about 120 mm to about 160 mm). The inner pipe 330 may have a length slightly shorter than the length of the outer pipe 300 such that the first inner pipe outlet 365 is located about 100 mm to about 300 mm (e.g., about 150 mm to about 250 mm, or about 175 mm to about 225 mm) from the first outer pipe closed end 310 of the outer pipe 300.

[0040] In at least one exemplary embodiment, the inner pipe 330 may have a bend 350 such that a portion of the inner pipe 330 extends through a hole 390 formed in the wall of the outer pipe 300. The bend 350 may be at an angle of about 90° relative to the remainder of the inner pipe 330. In other exemplary embodiments, the bend 350 may be at an angle of about 10° to about 80° relative to the remainder of the inner pipe 330. In other exemplary embodiments, the portion 350 may be an angled portion or a straight portion.

[0041] As shown in FIG. 3, in at least one exemplary embodiment, the heat exchange pipes 150 extend through a passageway 250 in the primary containment vessel 120 and through a penetration 240 in the top wall 200 of the reactor building 110 .

[0042] In at least one example embodiment, the PCCS 140 may include a seal 375 that surrounds each heat exchange pipe 150 where the heat exchange pipe 150 exits the penetration 240 in the top wall 200. The seal 375 may be any suitable heat resistant seal. As shown in FIG. 3 , the bend 350 begins at a point above the seal 375 and the top wall 200 of the reactor building 110.

[0043] In at least one exemplary embodiment, each of the heat exchange pipes 150 is supported by a support 380. The support 380 may include a spring 385 (or a flexible support) and a base 390. The spring 385 or flexible support has a first end that acts against the closed end of the outer pipe and a second end that acts against the base 390. The use of the spring 385 or flexible support for the support 380 allows the heat exchange pipes 150 to still be supported even as they expand due to heat absorption.

[0044] In at least one exemplary embodiment, the spring 385 can be between about 300 mm and about 500 mm in length. For example, the spring can be about 400 mm in length. The spring 385 can be formed of any suitable material, such as stainless steel.

[0045] FIG. 4 illustrates a top view of a portion of the boiling water nuclear reactor of FIG. 1 in accordance with at least one example embodiment.

[0046] As shown in Figure 4, in at least one exemplary embodiment, the PCCS 140 includes a plurality of heat exchange pipes 150 extending into the water-filled reactor cavity pool 130. The PCCS 140 may include 2-20 heat exchange pipes 150 (e.g., 3-19, 4-18, 5-17, 6-16, 7-15, 8-14, 9-13, or 10-12). As shown in Figure 4, for example, the PCCS 140 includes 10 heat exchange pipes 150. The heat exchange pipes 150 may be substantially uniformly spaced around the primary containment vessel 120. In other exemplary embodiments, the heat exchange pipes 150 may be non-uniformly spaced around the primary containment vessel 120 or may be arranged in clusters.

[0047] In use, the heat exchange pipes 150 of the PCCS 140 allow water to naturally circulate from the reactor cavity pool 130 into the primary containment vessel 120 through the inlet 370 of the inner pipe 330 of the heat exchange pipes 150. As the heat exchange pipes 150 absorb heat, the water is heated and converted to hot water, which is released through the outlet 325 on the outer pipe 300 of the heat exchange pipes 150.

[0048] At least one example embodiment relates to a method of installing a passive containment cooling system. The method of installing a passive containment cooling system includes positioning heat exchange pipes at least partially within a primary containment vessel such that a portion of the heat exchange pipes extends into a reactor cavity pool. If the passive containment cooling system is being retrofitted to an existing boiling water nuclear reactor, the method may include drilling penetrations and / or passages through a top wall of the reactor building and a portion of the primary containment vessel. The method may also include installing supports for each heat exchange pipe and installing the heat exchange pipes.

[0049] Although certain exemplary embodiments have been disclosed herein, it should be understood that other variations are possible. Such variations are not to be regarded as departing from the spirit and scope of the present disclosure, and all such modifications that would be apparent to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A boiling water nuclear reactor, A reactor building, a top wall portion forming a through hole therein; A bottom wall portion; At least one sidewall; a reactor building, wherein the top wall, the bottom wall, and the at least one side wall form a chamber within the reactor building; a reactor cavity pool adjacent to the reactor building; a primary containment vessel, at least a portion of which is within the chamber of the reactor building; a passive containment cooling system configured to receive water and discharge hot water; The passive containment cooling system comprises: At least one heat exchange pipe, the at least one heat exchange pipe comprising: an outer pipe having a first outer pipe end and a second outer pipe end, the first outer pipe end being closed and the second outer pipe end being open, the first outer pipe end being within the primary containment vessel and the second outer pipe end extending through the penetration in the top wall of the reactor building and into the reactor cavity pool such that the outer pipe is in fluid communication with the primary containment vessel and the reactor cavity pool, the outer pipe including a side pipe wall forming an opening therein; 11. A boiling water nuclear reactor comprising: an inner pipe at least partially within the outer pipe, the inner pipe having a first inner pipe end and a second inner pipe end, the first inner pipe end and the second inner pipe end being open, the second inner pipe end extending from the outer pipe into the reactor cavity pool such that the second inner pipe end is in fluid communication with the reactor cavity pool, the inner pipe including a bend between the first inner pipe end and the second inner pipe end, the bend extending through the opening in the side pipe wall into the reactor cavity pool.

2. 2. The boiling water nuclear reactor of claim 1, wherein the outer pipe has a diameter between 200 mm and 520 mm.

3. 2. The boiling water nuclear reactor of claim 1, wherein the inner pipe has a diameter of between 50 mm and 200 mm.

4. 2. The boiling water nuclear reactor of claim 1, wherein said inner pipe and said outer pipe are made of stainless steel.

5. 2. The boiling water nuclear reactor of claim 1 further comprising at least one seal about said outer pipe adjacent said penetration in said top wall of said reactor building.

6. 10. The boiling water nuclear reactor of claim 1, wherein the passive containment cooling system includes a plurality of heat exchange pipes.

7. 7. The boiling water nuclear reactor of claim 6, wherein the passive containment cooling system includes between 2 and 20 heat exchange pipes.

8. 10. The boiling water nuclear reactor of claim 1 further comprising at least one support in the primary containment vessel configured to support the first outer pipe end of the heat exchange pipe.

9. 9. The boiling water nuclear reactor of claim 8, wherein the support comprises a spring support configured to allow up and down movement of the heat exchange pipe caused by expansion due to absorption of heat.

10. 10. The boiling water nuclear reactor of claim 1, wherein the passive containment cooling system is valve-free, pump-free, or both valve-free and pump-free.

11. 1. A passive containment cooling system comprising: The heat exchange pipe is provided. an outer pipe having a first outer pipe end and a second outer pipe end, the first outer pipe end being closed and the second outer pipe end being open, the first outer pipe end being within a primary containment vessel of a boiling water nuclear reactor, the second outer pipe end extending into a reactor cavity pool such that the outer pipe is in fluid communication with the reactor cavity pool, the outer pipe including a side pipe wall defining an opening therein; an inner pipe at least partially within the outer pipe, the inner pipe having a first inner pipe end and a second inner pipe end, the first inner pipe end and the second inner pipe end being open, the second inner pipe end extending from the outer pipe into the reactor cavity pool such that the second inner pipe end is in fluid communication with the reactor cavity pool, the inner pipe including a bend between the first inner pipe end and the second inner pipe end, the bend extending through the opening in the side pipe wall into the reactor cavity pool; a passive containment cooling system.

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