System and method for a reactor core assembly receptacle leakage diverter

Abstract

A flow channel is formed in the reactor core receptacle and provides a flow path for leaked primary coolant. The flow path redirects the leaked coolant from an upward vertical direction, where the bulk flow would impart a lift-off force to the core assembly seated within the receptacle, toward a horizontal flow path that maintains the hydrodynamic balance of the core assembly. The flow channel within the reactor core receptacle provides a passive means that allows hydraulic hold-down of the core assembly even in the absence of mechanical hold-down.

Description

Technology Field

[0001] Government licensing rights

[0002] This invention was made with government support pursuant to DOE Cooperation Agreement DE-NE0009054, commissioned by the U.S. Department of Energy. The U.S. government holds specific rights to this invention.

[0003] Cross-reference

[0004] This application claims the benefit of priority to U.S. provisional patent application No. 63 / 621,104, titled “SYSTEMS AND METHODS FOR NUCLEAR CORE ASSEMBLY RECEPTACLE LEAKAGE DIVERTER,” filed on January 15, 2024, the full contents of which are incorporated herein by reference. Background Technology

[0005] In a sodium-cooled fast reactor ("SFR"), the main reactor components are a reactor vessel filled with liquid sodium coolant and a reactor core. In some cases, the SFR is a one-pass fast reactor operated by subcritical reloading fuel that is bred and burned on-site. The reactor core is immersed in a sodium pool within the reactor vessel. In one design, there are several rods of enriched uranium (U-235) in the center of the core, surrounded by rods of depleted uranium (U-238). U-235 acts as an initiator to start a traveling wave reaction, that is, a slow-moving chain reaction of parallel waves of fission traveling through the uranium rods. These parallel waves are initiated in the center of the core, slowly consuming fuel and generating heat in the core. This mode of operation is sometimes visualized as a reactor in which waves of fissile material traveling through the fuel are burned after being bred. However, in many cases, nuclear fission power plants also include a so-called 'standing wave' design, as an alternative to propagating the reaction radially outward through static rods, in which spent rods near the center of the reactor core are exchanged with unused uranium rods from the periphery of the reactor core.

[0006] Sodium coolant is used to remove heat from the core. The sodium coolant enters the nozzle of the core assembly and flows around the fuel fins within the core assembly, thereby flowing through the core assembly, of which some may be the fuel assembly, and removing heat from it. A containment vessel surrounds the reactor vessel to prevent loss of sodium coolant in the event of a leak from the reactor vessel, which is unlikely. Pumps circulate the primary sodium coolant between the reactor core and intermediate heat exchangers located within the pool. These heat exchangers have non-radioactive intermediate sodium coolant on the other side of the heat exchanger. The heated intermediate sodium coolant is circulated to a steam generator that generates steam to drive the turbine of an electric generator.

[0007] Theoretically, some SFR fission power plants do not require fuel reprocessing, use depleted or natural uranium as their primary fuel, require only a small amount of enriched uranium at startup, and require no fuel reloading at all. This core life depends on the scale of the initial uranium loading and the fuel burn achieved during reactor operation.

[0008] The reactor core may include various types of core assemblies, including core assemblies containing fissile fuel, breeder fuel, reflectors, and neutron absorbers. The force exerted by the flowing sodium on the core assembly typically exerts an upward force on the core assembly that tends to lift the core assembly out of its mounting socket. In some cases, the differential pressure exerted by the flowing sodium on the core assembly exerts a lifting force on the core assembly sufficient to lift one or more core assemblies out of the mounting receptacle, and there is a possibility that a series of consecutive events may occur, including a loss of control of the nuclear reaction.

[0009] Some reactor designs include a ring seal between the core assembly nozzle and the receptacle to prevent flowing sodium from passing between the core assembly and the receptacle to which the core assembly is mounted. Sodium leakage between the core assembly and the receptacle exerts significant lifting forces on the core assembly. However, ring seals can wear out and are typically manufactured from the same material as the receptacle; frictional forces degrade both the ring seal and the receptacle, making it very difficult to repair or replace either during the reactor's lifespan. Furthermore, if the ring seal fails catastrophically, it can cause the assembly to lose its hydrodynamic balance and be lifted.

[0010] In some SFR reactor designs, an upper hold-down is provided to limit the core assembly from being lifted upward.

[0011] It would be advantageous if the core assembly could rely on a hydraulic hold-down to maintain balance across the core assembly and keep it seated, which can be used to provide a redundant, passive, and efficient solution to mitigate core assembly lift-off. The above and other advantages will become apparent to those skilled in the art by referring to the following description, drawings, and claims. means of solving the problem

[0012] According to some embodiments, the benefit described herein is provided by a receptacle comprising: a cylindrical hollow body having an upper portion and a lower portion and further having an inner diameter and an outer diameter, as a receptacle within a reactor core configured to receive a nozzle of a core assembly; a mounting portion near the upper portion having an upper surface and a second diameter larger than the outer diameter of the cylindrical hollow body; and a plurality of flow channels formed on the upper surface of the mounting portion, configured to allow a primary coolant to flow therein.

[0013] The cylindrical hollow body may have an upper edge adjacent to the inner diameter, and the upper edge is inclined. In some cases, the inclined portion is provided at an angle inclined with respect to the longitudinal axis of the cylindrical hollow body.

[0014] In some cases, a plurality of flow channels are formed on an inclined upper edge. The plurality of flow channels may be formed radially with respect to a cylindrical hollow body. Thus, in some cases, the plurality of flow channels direct the flowing liquid from a substantially vertical flow direction to a substantially horizontal flow direction. In some embodiments, the plurality of flow channels form at least two sections, namely a first section having a vertical component of the flow and a second section forming a horizontal flow.

[0015] The above flow channel may have a semicircular cross-section, a V-shaped cross-section, and / or a rectangular cross-section. The flow channel may be formed during manufacturing by a material removal process, for example, by a machining operation.

[0016] In some cases, a sleeve or liner is disposed within the cylindrical hollow body, and the sleeve has a plurality of holes around the circumference of the sleeve that are aligned with the plurality of flow channels. The plurality of holes of the sleeve may each have a first area smaller than a second cross-sectional area determined by each of the plurality of flow channels. In this way, the fluid is encouraged to flow through the holes into the flow channels instead of being directed vertically in the assembly.

[0017] The above receptacle may further include an upper seal disposed over the plurality of holes of the sleeve, and the upper seal is configured to provide a seal between the inner surface of the sleeve and a nozzle inserted therein.

[0018] The receptacle may further include a lower seal disposed below the plurality of holes of the sleeve, and the lower seal is configured to provide a seal between the inner surface of the sleeve and a nozzle inserted therein. In some cases, the upper seal and / or the lower seal is one or more of a cylinder seal and a labyrinth seal. The upper seal may include multiple seals, such as two, three, four or more seals. The multiple seals may be of the same type or different types. For example, the upper seal may include one or more cylinder seals and one or more labyrinth seals.

[0019] In some cases, the plurality of holes in the sleeve are circular, whereas the plurality of holes may alternatively have an elliptical shape.

[0020] In some embodiments, the sleeve is formed of a nickel-chromium alloy.

[0021] According to some embodiments, a method for reducing lift-off forces acting on a core assembly within a reactor core comprises: providing a receptacle configured to accommodate the core assembly therein; and forming a flow channel on the top surface of the receptacle that redirects the flow of a fluid from a vertical direction to a horizontal direction. Thus, this flow redirection balances the hydrodynamic forces acting on the core assembly and changes the hydrodynamic forces from a vertical force to a radial force.

[0022] The step of forming the above flow channel may include machining a groove on the upper surface of the receptacle.

[0023] The above method may further include the steps of providing a sleeve within the receptacle and forming a plurality of holes in the wall of the sleeve. The holes may be formed perpendicular to the longitudinal axis of the sleeve or at an angle not perpendicular to the longitudinal axis.

[0024] The plurality of holes may be arranged to redirect the fluid flow from within the sleeve, through the holes, and into the flow channel. In some cases, this causes the fluid flow path to transition from a vertical position within the sleeve to an inclined position as the fluid flows through the holes into the flow channel, and then to a horizontal position within the flow channel. Brief explanation of the drawing

[0025] The accompanying drawings are part of this invention and are incorporated herein by reference. The drawings serve to illustrate examples of embodiments of this invention and, together with the detailed description and claims, to explain at least in part the various principles, features, or aspects of this invention. Specific embodiments of this invention are described more fully with reference to the accompanying drawings. However, various aspects of this invention may be embodied in various forms and should not be interpreted as being limited to the embodiments presented herein. Similar reference numbers throughout indicate elements that are similar but not necessarily identical or equivalent. The following drawings, which form part of this application, illustrate the described technology and are not intended to limit the scope of the claimed technology in any way, and the scope thereof shall be based on the claims attached to this application. FIG. 1 illustrates some of the basic components of a sodium-cooled fast reactor according to some embodiments in the form of a block diagram. FIG. 2 is a schematic cross-sectional view of the core of a sodium-cooled fast reactor according to some embodiments. FIG. 3 is an exploded view of a core assembly according to some embodiments. FIG. 4 is an enlarged cross-sectional view of the interface between the inlet nozzle and the core support structure according to some embodiments. FIG. 5 is a partial cutaway view of an inlet nozzle and core support structure showing a receptacle, sleeve, and core components according to some embodiments. FIG. 6a is a plan view of a receptacle having a flow channel according to some embodiments. FIG. 6b is a front view of a receptacle having a flow channel according to some embodiments. FIG. 7 is a schematic partial cross-sectional view of a receptacle and a sleeve according to some embodiments. FIG. 8 is a partial forward cross-sectional view illustrating a flow path from inside the sleeve to a location outside the sleeve according to some embodiments. Specific details for implementing the invention

[0026] The present invention provides exemplary embodiments and is not intended to limit the scope of the embodiments and the appended claims in any way. The embodiments are described above with the help of functional building blocks that exemplify the implementation of the designated functions and their relationships. The boundaries of these functional building blocks are arbitrarily defined herein for convenience of explanation. Alternative boundaries may be defined to the extent that the designated functions and their relationships are adequately performed.

[0027] FIG. 1 illustrates some of the basic components of a sodium-cooled fast reactor (SFR) fission power plant (100) in block diagram form. Although an SFR may be used as an exemplary type of reactor technology throughout this specification, it should be understood that the concepts presented in this specification are equally applicable to other types of reactors. In some cases, the concepts presented in the following description are directly applicable to other types of sodium-cooled fast reactors (SFRs), such as traveling wave reactors, modular reactors, microreactors, etc., and this specification and the appended claims are not limited to any specific reactor, fuel source, coolant type, or reactor architecture.

[0028] Generally, an SFR nuclear fission power plant (100) comprises a reactor core (102) containing a plurality of fuel assemblies (not shown). The core (102) is placed within a pool (104) containing a predetermined volume of liquid sodium coolant (106). The pool (104) is referred to as a high-temperature pool and has a higher sodium temperature than a surrounding low-temperature pool (108) that also contains liquid sodium coolant (106) (due to the energy generated by the fuel assemblies within the reactor core (102)). The high-temperature pool (104) is separated from the low-temperature pool (108) by a redan (110). An inert cover gas, such as argon, is filled into the headspace (112) above the level of the sodium coolant (106). The reactor vessel (114) surrounds the reactor core (102), the high-temperature pool (104), and the low-temperature pool (108), and is sealed by a reactor head (116). The reactor head (116) provides various access points to the interior of the reactor vessel (114).

[0029] The size of the reactor core (102) is selected based on a number of factors including the characteristics of the fuel, the desired power production, and the available space for the reactor (100). Various embodiments of the SFR fission power plant can be used for low power (about 300 MWe to about 500 MWe), medium power (about 500 MWe to about 1000 MWe), and high power (about 1000 MWe or more) applications, as required or desired. The performance of the reactor (100) can be enhanced by providing one or more reflectors (not shown) around the core (102) to reflect neutrons back toward the core (102). Additionally, the breedable and fissile fuel assembly can be moved (or "shuffled") within and relative to the core (102) to control the nuclear reaction occurring therein.

[0030] Sodium coolant (106) is circulated within the vessel (114) via a primary sodium coolant pump (118). The primary coolant pump (118) draws sodium coolant (106) from the cold pool (108) and injects it into the plenum below the reactor core (102). The coolant (106) is forced upward through the core and is heated by the nuclear fission reaction occurring within the reactor core (102). The heated coolant (106) exits the top of the core (102) and enters the intermediate heat exchanger(s) (120) from the hot pool (104), exits the intermediate heat exchanger (120), and re-enters the cold pool (108). Thus, this primary coolant loop (122) completely circulates the sodium coolant (106) within the reactor vessel (114).

[0031] The intermediate heat exchanger (120) always includes a segment of liquid sodium closed loop physically separated from the primary sodium pools (106 and 108) (i.e., the intermediate sodium and primary sodium are never mixed together). The intermediate heat exchanger (120) transfers heat from the primary coolant loop (122) (which is completely contained within the vessel (114)) to the intermediate coolant loop (124) (which is only partially located within the vessel (114)). The intermediate heat exchanger (120) passes through the redan (110) to connect the high-temperature pool (104) and the low-temperature pool (108) (allowing sodium (106) in the primary coolant loop (122) to flow between them). In one embodiment, four intermediate heat exchangers (120) are distributed within the vessel (114). Alternatively, two or six intermediate heat exchangers (120) may be distributed within the vessel (114), or other numbers of heat exchangers (120) may be distributed across the reactor vessel (114).

[0032] The intermediate coolant loop (124) circulates sodium coolant (126) passing through pipes in and out of the vessel (114) via the reactor head (116). An intermediate sodium pump (128) located outside the reactor vessel (114) circulates the sodium coolant (126) to the power generation system (123). Heat is transferred from the sodium coolant (106) of the primary coolant loop (122) to the sodium coolant (126) of the intermediate coolant loop (124) in the intermediate heat exchanger (120). The sodium coolant (126) of the intermediate coolant loop (124) passes through a plurality of tubes (130) within the intermediate heat exchanger (120). These tubes (130) transfer thermal energy between the sodium coolant (106) of the primary coolant loop (122) while keeping it separated from the sodium coolant (126) of the intermediate coolant loop (124).

[0033] A direct heat exchanger (132) extends into the high-temperature pool (104) and typically provides cooling to the sodium coolant (106) in the primary coolant loop (122) in an emergency. The direct heat exchanger (132) is configured to allow the sodium coolant (106) to enter the heat exchanger (132) from the high-temperature pool (104) and exit the heat exchanger (132). The direct heat exchanger (132) may have a configuration similar to that of an intermediate heat exchanger (120), in which tubes (134) transfer thermal energy between the NaK (sodium-potassium) of the primary coolant loop (122) while keeping it separated from the direct heat exchanger coolant (NaK) (136) of the direct reactor coolant loop (138).

[0034] Other auxiliary reactor components (both inside and outside the reactor vessel (114)) include, but are not limited to, pumps, check valves, shut-off valves, flanges, drain tanks, etc., which are not illustrated but will be obvious to those skilled in the art. Additional reactor head (116) penetrations (e.g., ports for the primary coolant pump (118), inert cover gas and inspection ports, sodium treatment and cover gas ports, etc.) are not illustrated. A control system (140) is used to control and monitor the various components and systems constituting the reactor (100).

[0035] Broadly speaking, the present invention describes a configuration that improves the performance of the reactor (100) described in FIG. 1. Specifically, examples, configurations, and arrangements of a flow control system used to direct sodium in a manner that minimizes or at least reduces the lift-off force of the core assembly. In particular, the system, components, and methods described herein reduce the lift-off force caused by sodium leaking into the space between the core assembly and the receptacle holding the core assembly. These features are illustrated and described in more detail below with reference to the drawings below.

[0036] FIG. 2 is a schematic cross-sectional view of the core (200) of an SFR. The core (200) is schematically illustrated and includes a central core region (202) having a plurality of core assemblies (204). The core assemblies (204) may include fissile fuel assemblies, breeding fuel assemblies, shielding assemblies, reflector assemblies, control assemblies, pre-stop assemblies, or material test assemblies. Generally, the contents of the assemblies (e.g., fissile material, control material, etc.) identify a specific assembly. The components of the assemblies containing these materials may be identical to facilitate shuffling the core assemblies around the core to any position as desired. The peripheral core region (206) includes a storage port (208) within the container. Throughout the life of the core (200), the fissile fuel assemblies and breeding fuel assemblies (as well as certain other assemblies) are shuffled between the central core region (202) and the peripheral core region (206). This is performed at various stages of the core life as required or desired to initiate, maintain, accelerate, or terminate nuclear reactions or power generation, and / or for safety reasons.

[0037] The assembly (204) is configured to accommodate the core assembly (204) and is accommodated by the upper plate (210) of the core support structure (212) at a size-set position. Sodium coolant is pumped toward the plenum (214) placed below the upper plate (210) and flows upward toward the core assembly (204), where it is heated by the nuclear reaction occurring within the core (200). A structure for channeling the flow of sodium through the core (202) and toward various assemblies is described below.

[0038] FIG. 3 is an exploded view of a core assembly (300). The assembly (300) includes an elongated duct (302) having an axis (A). The duct (302) has a hexagonal cross-section. A handling socket (304) having an internal flow passage is fixed to a first end (306) of the duct (302) and has internal or external features that allow the assembly (300) to be grasped by a mechanism within the reactor vessel to be raised, lowered, and otherwise moved into, out of, or within the core.

[0039] An inlet nozzle (308) is fixed to a second end (310) of the duct (302). A plurality of bearing rings (312) and retaining rings (314) are used to attach the handling socket (304) and the inlet nozzle (308) to the duct (302). A plurality of (two in this embodiment) locking fixing plates (316) and a plurality of pin strip rails (318) may be included near the end of the inlet nozzle (308). The locking fixing plates (316) and the pin strip rails (318) together connect a pin bundle (320) to the inlet nozzle (308). A seal ring (322) and a flow restrictor (324) may also be included. The nozzle (308) forms a plurality of coolant inlet windows (326) that flow-communicate with an internal flow chamber (not shown) extending through the nozzle (308). Accordingly, the window (326) provides a path for sodium to flow toward the nozzle (308) and toward the duct (302) and around the fin bundle (320) placed inside it. The sodium flow leads out of the handling socket (304).

[0040] FIG. 4 is a cross-sectional view of an exemplary flow control system (500) showing an interface between an inlet nozzle (308) and a core support structure (400). The inlet nozzle (308) is seated and coupled to a receptacle (402) of the core support structure (400). The nozzle (308) may have an inclined surface (408) that provides a funnel-shaped transition between a first diameter of the nozzle (308) and a second diameter of the duct (302) which is larger than the first. In some cases, the inclined surface (408) is positioned against the receptacle (402), whereas in other cases, the inclined surface (408) may be positioned over the receptacle (402). The interface between the inclined surface (408) and the receptacle (402) may be determined based on the design of the receptacle and how deeply the core assembly (300) is configured to be inserted into the receptacle. In some cases, there is a gap between the nozzle (308) and the receptacle (402) as described in more detail later.

[0041] The base (404) of the receptacle (402) forms a passage (406) that provides a flow path for sodium to pass through the core assembly (300) and exit into the reactor sodium hot water pool. The receptacle (402) may extend over the core support structure (400) or may be coplanar. Below the core support structure (400) is a coolant flow control system (500), which includes a masking element (502) and a flow stack (504) disposed therein. In this embodiment, the masking element (502) is in the form of a sleeve. The flow stack (504) may include an outer housing (506) and at least one flow control assembly (508) disposed therein. The flow control system (500) is described in more detail later.

[0042] A suitable flow system may utilize a standardized flow stack with various masking sleeves at multiple locations beneath the core support structure. While the masking feature may be fixed to or integrated with the core support structure, the flow stack may be integrated with the core assembly or separated from the core assembly. By using a standardized flow stack, manufacturing costs, inter-assembly variations, and the risk of incorrect assembly are reduced due to the use of standardized components. The masking sleeve allows the flow stack to be used at any location across a wide range of flow conditions, such as those encountered in the SFR. The flow stack may be integrated with the core assembly inlet nozzle or fixed within the masking sleeve. The flow stack may include multiple pressure stages and an inlet for each stage. The masking sleeve may be positioned around the flow stack to create selective inlets to the flow stages. This arrangement allows for varying pressure drops depending on the exposed selective inlets, which consequently determines the number of pressure drop stages the flow encounters. This allows for the standardization of fuel assemblies while creating unique flow conditions for various core locations.

[0043] In the case of an SFR, this can be advantageous as it allows the core assembly to be installed at different core locations or relocated (e.g., shuffled) at any time while still accommodating the appropriate metering flow rate (which may vary by location). In an embodiment where the flow stack is integrated with the inlet nozzle, the flow stack is connected to a removable component (e.g., the core assembly). In this way, life-cycle effects (such as erosion damage) can be inspected and mitigated as needed. In the case of a "re-core" operation where all core assemblies are replaced with core assemblies of a different design, the replacement assembly does not need to conform to the flow zone of the original core, allowing for greater flexibility in the design of future cores if required or desired.

[0044] FIG. 5 illustrates a partial cutaway view of an inlet nozzle (308) and a core support structure (400) showing a receptacle (402), a sleeve (502), and a core component (300) according to some embodiments. In some embodiments, the receptacle (402) has a sleeve configured to accommodate the nozzle (308) of the core assembly (300) as a sleeve (502) inserted therein. In some cases, the sleeve (502) is formed of a hard material, which in some embodiments may be a nickel-chromium alloy such as one of the alloys sold by Huntington Alloys Corp. under the trade name Inconel. In some cases, the sleeve (502) may be designed to last for the entire life of the reactor core and may not be designed to be replaced.

[0045] On the other hand, when the reactor core is refueled and the core assembly is inserted into or removed from the reactor core, the nozzle (308) may often be replaced. Thus, in some cases, the nozzle (308) is formed of a material that is softer than the sleeve (502) material to promote the preferential wear of the nozzle (308) instead of the sleeve (502).

[0046] The sleeve (502) may be held down within the receptacle (402). In some cases, the sleeve (502) is formed integrally with the receptacle (402) and is secured in place, for example, by an interference structure (505) that prevents the sleeve (502) from being pulled out of the receptacle (402). The interference structure may be any suitable type of cooperative component and may include, for example, a shelf, a groove, a boss, a protrusion, a pocket, a fastener, a weld, a key fit, or other structures. In the illustrated embodiment, the cup (510) is held firmly by the receptacle. A bypass tube (516) allows sodium to flow throughout the core assembly. A pin (514) may be provided to inhibit relative movement between the receptacle (402) and the cup (510). A portion of the sleeve (502) can be captured by the cup (510), and the sleeve can be prevented from being pulled out of the receptacle (402).

[0047] The nozzle (308) may have a flow hole (512) formed therein, as described herein, to allow the coolant to flow through the core assembly (300). As the coolant enters the side of the receptacle (402) and into the core assembly (300), the coolant may flow into the space between the nozzle (308) and the sleeve (502) due to leakage of the coolant. As this leakage flows upward under pressure, it may strike the core assembly, for example, the inclined outer surface (518) of the core assembly (300), and may generate a vertical force sufficient to lift the core assembly (300) from the receptacle (402) and the sleeve (502). If this lifting force is sufficient to displace the core assembly (300), it may result in consequences such as reduced flow and a chain effect on the reactivity of the reactor.

[0048] FIG. 6a illustrates a plan view of a receptacle (402) having a fluid channel (602), and FIG. 6b is a front view of the receptacle (402) showing the fluid channel (602). The receptacle (402) may comprise a generally hollow cylindrical body (604) having a hollow portion (606) within it, said hollow portion (606) configured and sized to accommodate a nozzle of a core assembly. The receptacle (402) may additionally have an inwardly inclined inner upper edge (608) to help guide the core assembly inserted therein. The receptacle has a shoulder (612) and an upper surface (610) that can engage with a core support structure (400 in FIG. 5) to secure the receptacle to the core support structure.

[0049] A series of flow channels (602) may be formed on the upper surface (610) of the receptacle. The flow channels (602) may be formed radially with respect to the cylindrical body (604), and accordingly, flow through the flow channels (602) occurs radially.

[0050] The flow channel (602) may be formed to have any suitable cross-sectional shape, but in some cases, it is a round, curved, or rectangular cutout on the top surface of the receptacle (402). In some cases, the flow channel (602) is formed by a material removal process during the manufacture of the receptacle and may be formed by machining. The material removal may be a low-tolerance process in that high precision is not required to provide a flow channel to send the leaked coolant elsewhere.

[0051] The flow channels (602) may be spaced apart by a predetermined distance or angle offset from adjacent flow channels (602), and in some cases, 16, 20, 24, 28, or 32 or more flow channels may be provided at regular intervals around the periphery of the receptacle. The flow channels (602) may additionally be formed within the inclined inner upper edge (608), thereby providing a smooth flow path that diverts the leaking coolant from a vertical flow path to an inclined flow path, and eventually to a horizontal flow path.

[0052] FIG. 7 is a schematic partial cross-sectional view of a receptacle (402) and a sleeve (502) according to some embodiments. The sleeve (502) is configured to have a series of through holes (702) around its circumference. The holes (702) allow fluid to flow from inside the sleeve through the holes to a location outside the sleeve. At least some of the holes (702) of the sleeve may be aligned with a flow channel (602) formed in the receptacle (402). Thus, in combination with the flow channel (602), the holes (702) provide a fluid flow path for the fluid leaked to a location between the nozzle and the sleeve (502), and also provide a flow path that diverts the flow of the coolant in a direction that does not impart a lifting force to the core assembly.

[0053] The diverted flow path is illustrated by an arrow (704) showing that flow from within the sleeve (502) passes through the hole (702) and is directed into the flow channel (602). In some cases, the hole is significantly larger than the gap between the sleeve (502) and the nozzle to encourage a low-resistance flow path for the coolant. Likewise, the flow channel (602) may be significantly larger than the gap between the sleeve (502) and the nozzle to encourage leakage coolant to flow through the flow channel (602). Additionally, a seal may be provided in the gap between the sleeve (502) and the nozzle to further encourage fluid flow through the hole (702) and the flow channel (602). In some cases, the hole (702) may be uniform in size and formed in a circular, elliptical, oval, rectangular, rectangular with rounded corners, or other suitable shape. In some cases, the hole (702) has an area corresponding to the area of ​​the flow channel (602). In some cases, the hole (702) has a cross-sectional area smaller than that of the flow channel (602). This configuration can provide a pressure drop in the flow channel (602), which also encourages leaked coolant to flow along the flow channel (602). In some cases, the hole (702) is formed to have a diameter larger than the gap between the nozzle and the sleeve (502) to facilitate fluid flow through the hole (702). In some cases, the hole may be sized to be about 200%, or 300%, or 400%, or 500%, or 600%, or 700% or more of the size of the gap between the nozzle and the sleeve. For example, if the gap between the nozzle and the sleeve is about 2 mm, the hole may be formed with a diameter of 4 mm to 14 mm. In embodiments that may not have a circular hole, the minor dimension (e.g., the minor radius of the oval or the shorter side of the rectangular cutout) may be 4 mm to 14 mm.

[0054] The flow channel (602) may be formed to have a cross-sectional area larger than the hole to facilitate bending flow while introducing a pressure drop. As illustrated, the flow channel is formed below the top surface of the receptacle (402). Initially, the flow channel (602) causes a vertical component of the flow, and then this vertical component is transferred to a horizontal flow path. The hole (702) of the sleeve is located below the upper plate, and the flow channel (602) is formed at a similar or identical vertical position relative to the hole of the sleeve (502).

[0055] FIG. 8 is a partial forward cross-sectional view illustrating a flow path from inside the sleeve to a location outside the sleeve according to some embodiments. Fluid flow (704) may initially be seen inside the sleeve (502), where the fluid flows through a hole (702) formed in the sleeve and through a flow channel (602) within the receptacle (402). The illustrated embodiment shows the hole being formed radially, or, in other words, perpendicular to the longitudinal axis of the sleeve, but the hole may be formed at an angle other than perpendicular. For example, if the inclined edge of the receptacle is formed at a 45-degree angle, the hole may be formed (e.g., drilled) at a 45-degree angle so that the flow path through the sleeve aligns with the flow channel formed at the inclined edge of the receptacle. This configuration may further reduce the differential pressure to encourage the fluid to flow through the hole and into the flow channel, thereby redirecting the flowing fluid from the vertical direction to the horizontal direction.

[0056] In some embodiments, a first seal (802a) or a set of seals may be provided below the hole (702). This also encourages leaked coolant to flow through the hole (702) and through the flow channel (602). A second seal (802b) or a set of seals may be provided above the hole (702). In some cases, seals are provided below the hole (702) and above the hole (702) to encourage leaked coolant to flow through the hole (702) and along the flow channel (602).

[0057] The seal may be any suitable type of seal, but in some cases, it may be one or more of a labyrinth seal, piston ring, cylinder seal, or other types of seals that restrict fluid flow through the seal. In some cases, a labyrinth seal is created by forming grooves or channels on the surface of the sleeve or nozzle, or both. The grooves or channels impart turbulent fluid flow to the fluid flowing through them, thereby causing increased pressure and flow resistance. A piston seal is an overall annular seal that contacts both the sleeve and the nozzle. A piston seal may be formed from a compliant material or from a hard material such as Inconel, steel, or other suitable material. A piston seal may be supported by the sleeve or by the nozzle.

[0058] An efficient, passive, and redundant safety feature is provided by offering a flow path that encourages the diversion of leaked coolant from the vertical to the horizontal direction to reduce lift-off forces acting on the core assembly. The pressure drop due to the seal, in combination with flow redirection, can help reduce reliance solely on the seal to reduce lift-off forces and help reduce the accumulation of metal debris on the seal. In some cases, preferential wear of the nozzle can cause metal debris to accumulate within the lower seal, which can reduce its effectiveness. Consequently, having a redundant and passive structure that redirects the leaked coolant flow increases reliability and reduces the risk of the core assembly being lifted out of the receptacle without any additional mechanical constraints. Thus, the weight of the core assembly, in combination with hydrodynamic forces, is sufficient to maintain the core assembly in a fully seated position within the receptacle. The foregoing description of the embodiments results in a hydrodynamic balance across the core assembly, so that the core assembly remains seated within its respective receptacle.

[0059] The description of the specific embodiments described above is sufficient to reveal the general characteristics of the embodiments of the present invention, so that others, by applying the knowledge of those skilled in the art, will be able to easily modify and / or adapt the specific embodiments described above for various uses without excessive experimentation and without departing from the general concept of the embodiments of the present invention. Accordingly, such modifications and adaptations are intended to be within the meaning and scope of equivalents of the disclosed embodiments based on the teachings and guidelines set forth herein. Since the phrases or terms in this specification are for illustrative purposes only and not for limiting purposes, the terms or phrases in this specification should be interpreted by those skilled in the art in light of the teachings and guidelines set forth herein.

[0060] The breadth and scope of the embodiments of the present invention shall not be limited by any of the exemplary embodiments described above, but shall be limited only by the following claims and their equivalents.

[0061] In particular, conditional language such as “can,” “can be,” “may be,” or “may be,” is generally intended to convey that a particular embodiment includes a particular feature, element, and / or operation while another embodiment does not, unless specifically stated otherwise or otherwise understood within the context in which it is used. Accordingly, such conditional language is generally not intended to imply that a feature, element, and / or operation is required in any way in one or more embodiments, or that one or more embodiments necessarily include logic for determining whether the said feature, element, and / or operation should be included or performed in any particular embodiment, with or without the use of user input or prompting.

[0062] Unless otherwise noted, the terms “connected” and “combined” (and their derivatives) as used herein shall be interpreted to allow both direct and indirect (i.e., through other elements or components) connections. Additionally, the “indefinite article” as used herein shall be interpreted to mean “at least of.” Finally, for convenience of use, the terms “comprising” and “having” (and their derivatives) as used herein are interchangeable with and have the same meaning as the term “comprising.”

[0063] The specification and the accompanying drawings disclose embodiments of systems, apparatuses, devices, and technologies capable of providing control and optimization of coolant flow through a core assembly. Of course, it is not possible to describe all conceivable combinations of elements and / or methods for the purpose of describing the various features of the present invention, but those skilled in the art recognize that numerous additional combinations and substitutions of the disclosed features are possible. Accordingly, various modifications to the present invention may be made without departing from the scope or spirit of the present invention. Furthermore, other embodiments of the present invention may become apparent through consideration of the specification and the accompanying drawings and through the practice of the disclosed embodiments as presented herein. The examples proposed in the specification and the accompanying drawings should be considered in all respects as illustrative rather than limiting. Specific terms are used herein, but these terms are used only in a general and descriptive sense and are not used for the purpose of limitation.

[0064] From the foregoing, it will be understood that while specific embodiments are described herein for illustrative purposes, various modifications may be made without departing from the spirit and scope of the appended claims and the elements listed therein. Furthermore, while specific embodiments are presented below in specific claim forms, the inventors of this application consider various embodiments in any available claim forms. For example, some embodiments may be cited as currently being implemented in specific configurations, but other embodiments may likewise be implemented in this manner. Various modifications and alterations that will be apparent to those skilled in the art benefiting from this application may be made. It is intended to encompass all such modifications and alterations, and therefore the foregoing description should be considered illustrative rather than restrictive.

Claims

Claim 1 A receptacle within a reactor core configured to accommodate a nozzle of a core assembly, comprising: a cylindrical hollow body having an upper portion and a lower portion, and further having an inner diameter and an outer diameter; a mounting portion near the upper portion having an upper surface and a second diameter larger than the outer diameter of the cylindrical hollow body; and a plurality of flow channels formed on the upper surface of the mounting portion, configured to allow a primary coolant to flow therein. Claim 2 A receptacle according to claim 1, wherein the cylindrical hollow body has an upper edge adjacent to the inner diameter, and the upper edge is inclined. Claim 3 In paragraph 2, the plurality of fluid channels are a receptacle formed on the inclined upper edge. Claim 4 In paragraph 2, the plurality of flow channels are receptacles that orient the flowing liquid from a substantially vertical flow direction to a substantially horizontal flow direction. Claim 5 A receptacle according to claim 1, wherein the plurality of flow channels form at least two sections, namely a first section having a vertical component of the flow and a second section forming a horizontal flow. Claim 6 In claim 1, the fluid channel is a receptacle having a semicircular cross-section. Claim 7 In claim 1, the above-mentioned flow channel is a receptacle formed by a material removal process. Claim 8 A receptacle according to claim 1, further comprising a sleeve disposed within the cylindrical hollow body, wherein the sleeve has a plurality of holes aligned with the plurality of fluid channels around the circumference of the sleeve. Claim 9 A receptacle according to claim 8, wherein each of the plurality of holes has a first area smaller than the second cross-sectional area determined by each of the plurality of flow channels. Claim 10 A receptacle according to claim 8, further comprising an upper seal disposed over the plurality of holes, wherein the upper seal is configured to provide a seal between the inner surface of the sleeve and a nozzle inserted therein. Claim 11 A receptacle according to claim 8, further comprising a lower seal disposed below the plurality of holes, wherein the lower seal is configured to provide a seal between the inner surface of the sleeve and a nozzle inserted therein. Claim 12 In paragraph 10, the above upper seal is a receptacle in which one or more of a cylinder seal and a labyrinth seal. Claim 13 In paragraph 8, the above plurality of holes are circular in the receptacle. Claim 14 In claim 8, the receptacle wherein the plurality of holes are elliptical. Claim 15 In claim 8, the sleeve is a receptacle formed of a nickel-chromium alloy. Claim 16 A method for reducing a lift-off force acting on a core assembly within a reactor core, comprising: providing a receptacle configured to accommodate the core assembly therein; and forming a flow channel on the top surface of the receptacle configured to redirect the flow of a liquid flowing within the receptacle from an upward vertical direction to a horizontal direction. Claim 17 In claim 16, the step of forming the fluid channel comprises machining a groove on the upper surface of the receptacle. Claim 18 A method according to claim 16, further comprising the steps of providing a sleeve within the receptacle and forming a plurality of holes in the wall of the sleeve. Claim 19 A method according to claim 18, wherein the plurality of holes are arranged to redirect the fluid flow from within the sleeve, through the holes, and into the fluid channel. Claim 20 A method according to claim 18, wherein the fluid flow path transitions from a vertical position within the sleeve to an inclined position as the fluid flows through the hole into the flow channel, and then to a horizontal position within the flow channel.

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