Fuel handling systems, layouts and processes for nuclear reactors

Abstract

A method for treating spent nuclear fuel assemblies involves immersing the spent nuclear fuel assemblies in water for a relatively short period of time compared to conventional methods. The spent nuclear fuel assemblies are removed from the reactor core and inserted into a sodium removal machine having a receiver, a cleaning bin, and an elevator. A cleaning fluid is added to the cleaning bin and fuel assembly, and the fuel assembly is flushed with water while in the cleaning bin. The cleaning bin is at least partially submerged in the spent fuel pool during cleaning to provide passive heat removal. The cleaning bin is lowered into the spent fuel pool by the elevator. The fuel assemblies may then be loaded into racks and / or casks for long-term storage.

Description

Detailed Description of the Invention

[0001] [Government Licensing Rights] This invention was made with government support under DOE Cooperative Agreement No. DE-NE0009054 awarded by the U.S. Department of Energy. The government has certain rights in this invention.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Application No. 17 / 863,346, filed July 12, 2022. U.S. Application No. 17 / 863,346 is a continuation-in-part of, and claims priority to, U.S. Application No. 17 / 226,062, filed April 8, 2021. U.S. Application No. 17 / 226,062 claims priority to U.S. Provisional Patent Application No. 63 / 066,783, filed August 17, 2020. All of these applications are entitled "FUEL HANDLING SYSTEM, LAYOUT, AND PROCESS FOR NUCLEAR REACTOR," and the entire contents of each are incorporated herein by reference.

[0003] 〔background〕 The field of the disclosure relates to fuel handling systems, layouts and processes for one or more nuclear reactors. The removal of sodium from irradiated sodium fast reactor core components has traditionally been a bottleneck in the disposal of fuel and non-fuel sodium reactor irradiated core components.

[0004] It would be advantageous to be able to process irradiated core components significantly more efficiently and quickly, thereby improving safety and efficiency. These and other features and advantages will be readily appreciated by those skilled in the art upon review of the following discussion of related problems and proposed solutions.

[0005] 〔overview〕 One or more computer systems may be configured to perform specific operations or actions by installing software, firmware, hardware, or a combination thereof that, when operated, causes the system to perform the actions. One or more computer programs may be configured to perform specific operations or actions by including instructions that, when executed by a data processing device, cause the device to perform the actions. According to some embodiments, a method for storing a discharged core assembly includes coupling a cleaning canister to a fueling floor valve, inserting the discharged core assembly into the cleaning canister through the fueling floor valve, introducing a cleaning fluid into the cleaning canister, transporting the cleaning canister and the core assembly down an elevator to a spent fuel pool, and placing the core assembly in the spent fuel pool for storage. Other embodiments of this aspect may include corresponding computer systems, devices, and computer programs recorded on one or more computer storage devices, each configured to perform multiple actions of the method.

[0006] The method may further include the step of introducing a cleaning fluid, which is achieved by gradually increasing the water content in an inert gas. The method may include filling the cleaning receptacle with water and reacting residual sodium with the water. In some cases, coupling the cleaning receptacle to the fuel loading floor valve forms a pressure seal, and the step of introducing the cleaning fluid may be performed under pressure. The method may further include the step of at least partially placing the cleaning receptacle within the spent fuel pool during the step of introducing the cleaning fluid into the cleaning receptacle to provide passive cooling of the cleaning receptacle by the spent fuel pool.

[0007] The method may include loading the core assembly into a trolley and moving the trolley from a first position directly below the elevator to a second position within the spent fuel pool. The method may include flushing the core assembly with water in a first flow direction after the introducing the cleaning fluid. The method may further include flushing the core assembly with water in a second flow direction, the second flow direction being opposite to the first flow direction. This may be referred to as reverse fluid flow. The method may also include measuring a hydrogen concentration and determining that cleaning is complete based on the measured hydrogen concentration being less than a threshold. For example, during the cleaning process, the residual sodium reacts with water to generate hydrogen. The level of hydrogen concentration can be used to determine when the residual sodium has completely reacted with water. As the reaction of the residual sodium with water approaches completion, the hydrogen concentration approaches zero. In some embodiments, the method of cleaning may include determining that the hydrogen concentration is below a threshold, which may be a non-zero concentration.

[0008] The method may include removing the core assembly from the cleaning bin for storage and inserting a second core assembly into the cleaning bin, e.g., the cleaning bin may be reused for multiple core assemblies.

[0009] According to some embodiments, a sodium removal machine for cleaning an extracted core assembly is provided, and may include: a receiver coupled to a fuel loading floor valve, the receiver having one or more process fluid connections; a cleaning canister having an open upper end and a closed lower end; and an elevator configured to transport the cleaning canister from an upper position where the cleaning canister is coupled to the receiver and a lower position where the cleaning canister is not coupled to the receiver.

[0010] In some embodiments, the receiver is static and, when coupled to the cleaning bin, forms a closed boundary for the removed core assembly. In some cases, the receiver is statically coupled to the fuel loading floor valve, and the process fluid connection is similarly static within the receiver. When the cleaning bin is coupled to the receiver, the process fluid connection is positioned to add or remove fluid from the cleaning bin. The cleaning bin may include a receptacle configured to receive a portion of the removed core assembly, the receptacle configured to form a seal with the portion of the removed core assembly. In some cases, the receptacle is a hole, and the portion of the core assembly is a nozzle that fits through the hole. One or more of the process fluid connections may include a process fluid inlet positioned above the cleaning bin, such that process fluid passing through the process fluid inlet enters the cleaning bin and the core assembly. The receiver may have a first cross-sectional dimension and the core assembly may have a second cross-sectional dimension, the first cross-sectional dimension being less than two times the second cross-sectional dimension or less than 1.5 times the second cross-sectional dimension. In some cases, the receiver may have a first length and the core assembly may have a second length, the first length being less than two times the second length.

[0011] According to some embodiments, the elevator selectively couples with the cleaning bin, and in some cases, the elevator automatically decouples from the cleaning bin when the elevator is in the lower position.

[0012] In some embodiments, when the elevator is in the upper position, the cleaning bin is at least partially submerged in a spent fuel pool. This configuration allows passive cooling of the cleaning bin by the spent fuel pool. The sodium removal machine may include a hydrogen sensor configured to measure a hydrogen concentration at a process agent outlet of the cleaning bin.

[0013] In some cases, the core assembly occupies more than 50% of the diameter of the cleaning vessel, and in some cases, the core assembly may occupy more than 20%, or more than 30%, or even 40% or more of the volume of the cleaning vessel.

[0014] According to some embodiments, a method of storing an irradiated core component includes the steps of moving the irradiated core component to a pool immersion chamber, removing primary coolant from outside the irradiated core component by blowing an inert gas at the irradiated core component, applying wet inert gas to the irradiated core component, flooding the irradiated core component with water, and immersing the irradiated core component in a pool of water.

[0015] In some embodiments, the step of applying a moist inert gas is accomplished by gradually increasing the moisture content in the inert gas.

[0016] In some cases, applying a moist inert gas includes gradually increasing the water content in the inert gas to 100%. In some embodiments, the primary coolant may be sodium. Sodium may be present on the irradiated core components, and the sodium may be reacted with water.

[0017] The method may further include loading the irradiated core components into a cask while they are immersed in the pool of water. In some cases, the method is carried out for a period of less than about two hours.

[0018] In certain embodiments, the method includes flushing the irradiated core component with water while the component is immersed in the pool of water.

[0019] According to some embodiments, a method of handling spent nuclear fuel includes removing a spent fuel assembly from an in-core storage system within a reactor vessel, transferring the spent fuel assembly to a pool immersion cell, reacting residual sodium on the spent fuel assembly with water, and immersing the spent fuel assembly in a pool of water.

[0020] The method may further include storing the spent fuel assemblies in the pool of water for long-term decay. In some cases, the method includes loading the spent fuel assemblies into a cask.

[0021] In some embodiments, the step of loading the cask occurs in the pool of water. Optionally, the step of reacting the residual sodium occurs by passing a gas having a positive water content over the spent fuel assemblies. In some cases, the gas is an inert gas, and the gas may be argon.

[0022] The method may include increasing the moisture content of the gas, for example to about 100%, and the step of increasing the moisture content may be done gradually and may be stopped at any suitable moisture content.

[0023] In some cases, the method includes forming a passivation layer on the residual sodium. The passivation layer may be formed by reacting the sodium with a reactant (e.g., water) for a period of time. The passivation layer may be formed by applying water to the residual sodium to form a layer of sodium hydroxide.

[0024] The method may further include blowing a gas through the spent fuel assembly and measuring the flow rate of the gas through the spent fuel assembly. In some cases, the gas may be measured for the presence of reaction products, fission products, primary coolant, or some other characteristic.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a nuclear facility showing a reactor building, fuel handling facilities, and fuel storage facilities, according to some embodiments.

[0026] FIG. 2 is a perspective view of a schematic diagram of a nuclear facility, according to some embodiments.

[0027] FIG. 3 is a schematic diagram of a nuclear facility having multiple reactor buildings, fuel handling and fuel storage facilities, according to some embodiments.

[0028] FIG. 4 is a schematic diagram of a nuclear facility showing two reactor buildings and a shared refueling floor, according to some embodiments.

[0029] FIG. 5 is a perspective view of a nuclear fuel assembly, according to some embodiments.

[0030] FIG. 6 is a perspective schematic view of a core assembly inspection stand, conditioning cell, and jib hoist, according to some embodiments.

[0031] FIG. 7 is a schematic diagram of an EVHM mounted on a rail, according to some embodiments.

[0032] 8A and 8B are schematic diagrams of a pool immersion cell in plan and elevation views, respectively, according to some embodiments.

[0033] FIG. 9 is a sample process diagram for storing irradiated core assemblies, according to some embodiments.

[0034] FIG. 10 is a sample process diagram for storing irradiated core assemblies, according to some embodiments.

[0035] FIG. 11 is a perspective view of a pool immersed (PIC) cell showing an exemplary location of a sodium removal machine, according to some embodiments.

[0036] FIG. 12 is a perspective view of a PIC machine, according to some embodiments.

[0037] FIG. 13 illustrates a bottom loading transfer cask (BLTC) coupled to an embodiment of a PIC machine, according to some embodiments.

[0038] FIG. 14 is a cross-sectional view illustrating a mating structure between a BLTC and a PIC machine, according to some embodiments.

[0039] FIG. 15 is a partial cutaway view of a PIC machine showing the cleaning receptacle, according to some embodiments.

[0040] FIG. 16 is a diagram illustrating the motion of a PIC machine, according to some embodiments.

[0041] FIG. 17 illustrates a PIC machine elevator at its lower limit of travel, according to some embodiments.

[0042] FIG. 18 shows the PIC machine disengaged from the cleaning receptacle, according to some embodiments.

[0043] FIG. 19 shows the PIC machine in a full overtravel state with the cleaning receptacle disengaged, according to some embodiments.

[0044] FIG. 20 shows a PIC trolley with a cleaning container traveling to a spent fuel pool (SPF), according to some embodiments.

[0045] FIG. 21 shows the PIC machine and PIC top components, according to some embodiments.

[0046] FIG. 22 shows the upper area of ​​a cleaning vessel with a core assembly, according to some embodiments.

[0047] FIG. 23 shows the lower area of ​​the cleaning vessel with the core assembly, according to some embodiments.

[0048] FIG. 24 shows a cross-sectional view of a receiver and cleaning receptacle with seals and tubing connections, according to some embodiments.

[0049] FIG. 25 illustrates a cross-sectional view of a PIC receiver and cleaning receptacle, according to some embodiments.

[0050] FIG. 26 shows the process flow for cleaning the extracted core assembly.

[0051] Detailed Description The following detailed description provides a better understanding of the features and advantages of the invention described in this disclosure, in accordance with the embodiments disclosed herein. While this detailed description includes many specific embodiments, these are provided by way of example only and should not be construed as limiting the scope of the invention disclosed herein.

[0052] Previous sodium removal efforts used steam inert gas followed by a water flush. The sodium wetted components were placed into a pressure vessel with the assembly inlet mated to a semi-gas tight receptacle. The pressure vessel was closed and an inert gas flow was established. Wet steam was introduced into the gas inlet in a controlled manner. The hydrogen level in the gas stream exiting the pressure vessel was monitored, and the control was entered to increase the moisture level in the inert gas stream. As the sodium reacted, the moisture level was increased until the gas was 100% hydrogen-free. This process was typically performed in a dedicated hot cell, which was designed to handle the increased hydrogen pressure. Additionally, dedicated fuel handling equipment was required.

[0053] At that point, the pressure vessel was slowly flooded and water flow was initiated using a conventional pump. The ion levels in the water were monitored and replaced as needed until the water flowing through the assembly had low levels of sodium ions. The pressure vessel was then drained, and the treatment system and assembly were allowed to dry. The cleaned assembly was removed from the pressure vessel. Treatment times were approximately 18-24 hours for each assembly.

[0054] This treatment removed nearly all sodium and sodium reaction products. Stainless steel is typically used in fuel assemblies, and it is generally considered beneficial to achieve high cleanliness standards with respect to sodium hydroxide residue, especially in stressed areas.

[0055] In addition, in some cases, irradiated assemblies are sent directly to dry storage, post-irradiation examination, or reprocessing. Many regulatory standards, including spent fuel disposal acceptance standards, require very low levels of metal reactivity.

[0056] According to some embodiments, a rapid method is described below for placing sodium-wetted components in conventional water-filled spent fuel storage basins, significantly improving efficiency, reducing the equipment and buildings required to handle irradiated assemblies, and reducing potential radiation exposure to facility workers and the public.

[0057] (Refueling system layout in reactor building and fuel storage facility) 1, 2, 3, and 4, according to some embodiments, a general layout of reactor building(s) 100 and a Fuel Storage Facility (FSF) 110 is shown. In some embodiments, this layout plan has the flexibility to support up to four or more reactor units in a quad arrangement. However, for efficiency reasons, only two units, a first reactor building 100 and a second reactor building 112, are shown. In some cases, the buildings may be arranged as shown in FIG. 3 or 4. This allows for shared refueling equipment and also allows for a larger crane envelope for reactor building (RB) maintenance and potential large component cask transfers in the maintenance and refueling space 302. This would allow the RB crane to place large casks onto the rails of a bottom-loading transfer cask for transport to the FSF / Maintenance Facility 110. In some cases, the transfer hall 304 and the FSF / Maintenance building 110 may be separate structures, with only the fuel loading and maintenance facility having a separate overhead crane, while in some embodiments the transfer hall is part of the FSF / Maintenance facility 110. Estimated refueling and maintenance footprints according to some example embodiments are set forth in Table 1 below.

[0058] [Table 1]

[0059] Of course, other layouts, dimensions, configurations, and building counts are entirely possible within the scope of this disclosure. Any physical dimensions, including dimensions, heights, sizes, weights, etc., are provided for illustrative purposes only and are not intended to limit the scope of this disclosure unless otherwise specified in the appended claims.

[0060] In some cases, a residual heat removal (RHR) system 114 is provided to assist in decay heat removal, and one RHR system 114 may be associated with each reactor building 100, 112. One or more control building modules 116 may be provided to monitor and / or operate the reactor within the reactor building. In some cases, auxiliary buildings such as warehouse 118 space and remote fuel storage area 120 may be provided.

[0061] 4, in some cases, a refueling system includes a central control facility that monitors the high-level operation of the conditioning cell, bottom loading transfer cask (BLTC) 402, Ex-Vessel Storage Tank (EVST) 404, Ex-vessel handling machine (EVHM) 406, transfer adapter, transfer station lift, In-vessel Transfer Machine (IVTM), rotating plug, pool immersion cell 410, pool cooling and cleanup system, pool core assembly handling machine 412, and other components and systems. Local refueling control points may have plant-based data and communication networks that communicate information to the central refueling control room.

[0062] In some cases, new core assemblies arrive from suppliers and are erected in transport containers at FSF 110. A jib hoist and grapple tool may be used to transfer vertical (vertical) core assemblies to an inspection table and onto a conditioning cell. Prior to outage, a BLTC may be used to pick up conditioned core assemblies from the conditioning cell and transfer them to an EVST inside the reactor building. In some embodiments, the EVST may be sodium EVST, argon EVST, or may comprise another material that may be inert. In some cases, during outage, an EVHM may transfer core assemblies between the EVST and the reactor transfer adapter. An EVHM hoist may be used to transfer the core assemblies through the transfer adapter to a cover gas region, where they are handed off to a transfer station lift below the reactor's refueling port. A transfer station lift may vertically move the core assembly between the cover gas region and the IVTM refueling region above the top of the core. In some embodiments, the IVTM, in combination with the movement of a rotating plug, moves the core assembly between the transfer station lift, the core location, and an In-Vessel Storage (IVS) location for collapse.

[0063] According to an exemplary method, a spent fuel assembly can be removed from an IVS location within the reactor by an IVTM, and the spent fuel assembly can be transferred to a transfer station lift. The transfer station lift can be used to lift a fuel or non-fuel core assembly into a cover gas region, where an EVHM hoist and grapple engage the assembly. The EVHM can then lift the core assembly, remove it from the reactor through a transfer adapter, and lift the core assembly into an EVHM cask on the refueling floor. Once the EVHM cask is secured, the core assembly can be transferred to an EVST, where it remains during refueling batch transfer.

[0064] The method may include additional steps. For example, following shutdown, the BLTC may pick up the spent core assemblies and transport them to the FSF to be packaged as waste or processed for spent fuel storage. In a wet cask loading method, the BLTC may transport some or all of the core assemblies to a pool immersion cell where sodium reacts, immersing the assemblies in water, and then transporting the assemblies to a larger spent fuel pool. Pool handling machinery may be used to move the fuel assemblies to storage racks for long-term decay (e.g., 10 to 15 years). As known to those skilled in the art, some or all of the core assemblies may be ultimately disposed of in casks within the pool, such as in a typical light water reactor cask loading process. The fully dried and inerted spent fuel casks may be transported to a site storage pad, and the waste (non-fuel) casks may be sent to a long-term waste repository.

[0065] (Detailed refueling process description according to some embodiments:) (Arrival of new core assembly (assembly of fuel, control rods, shields, and reflectors)) Refer to FIG. 5. FIG. 5 illustrates a representative example of a core assembly 500. A new core assembly may consist of a drive fuel, control rod, shield, and reflector core assembly. In some cases, the core assembly 500 includes a duct 502 defining a nozzle assembly 504 at a first end, an upper core load pad 506, and a handling socket 508 at a second end. In some cases, the core assembly 500 may have a consistent hexagonal exterior configuration. Within the core assembly 500, a fuel pin bundle assembly 510 is secured within the duct 502. The fuel pin bundle assembly 510 may include any suitable number of fuel pins. A series of coolant inlet ports 512 allow coolant to enter the core assembly 500, flow through the duct 502, and absorb heat from the fuel pin bundle assembly 510.

[0066] In some cases, the core assemblies 500 arrive at the reactor site in transport containers. Each container may contain four core assemblies. The transport containers may be unloaded from the supplier's truck by an FSF overhead crane or forklift. The transport containers may be stored in a secure area at the FSF until their inspection and conditioning are required for outage. The transport containers may be used for the protection and safety of the assemblies prior to outage, as they have appropriate component supports, vibration monitors, FME protection, and environmental controls.

[0067] During initial reactor construction, additional full core loadings of dummy core assemblies (e.g., core assemblies without fuel) may be used to test the criticality characteristics of the reactor and systems. Depending on their design, these dummy assemblies may also be used to maintain the core configuration during later refueling or maintenance operations. Because the dummy assemblies contain no fuel, they require only normal radioactive waste disposal management. Specialized core assemblies with start-up neutron sources may also be provided for initial reactor startup. These start-up sources, due to their radioactive source content, may be treated as fuel for final disposal. Both of these core assembly types may follow normal core assembly handling processes used for reactor refueling and disposal.

[0068] In some cases, an outage batch is estimated to be 18 months long and contain 30 fuel assemblies and 10-15 control rods. In preparation for a refueling outage, the transport vessel may be brought to a vertical position by an uprighting mechanism so that the core assemblies contained within canisters can be grappled by a top entry grapple tool. The canister may be opened under strict cleanliness controls, for example, to avoid contamination.

[0069] Referring to FIG. 6, a jib hoist 600 may be attached to a jib hoist mount 602 and may carry a top-entry grapple tool. The top-entry grapple tool may be configured to engage each core assembly in the transport vessel and transfer them to the inspection bench. In some embodiments, the grapple tool may have approximately three to four grapple fingers that engage with the core assembly handling sockets 508 for safe lifting. FIG. 6 further illustrates a potential layout of the jib hoist 600, conditioning cell 604, and inspection bench 606. The emptied core assembly transport vessel may be returned to a supplier for future batch reloading and is typically not part of the plant equipment.

[0070] In some cases, the inspection platform 606 may be seismically qualified, may include a vertical elevator 608 to handle two (or more) core assemblies, and may be located in a pit 610 on the transfer hall floor near the conditioning cell 604. Once an assembly is loaded into the platform 606, the elevator 608 may raise the assembly past an operator for a full-length inspection process. The assembly may have its identity recorded, may be scanned for potential shipping damage, and may be verified to be clean and free of foreign material. The core assembly's identity may be transferred to the plant's refueling database for tracking of the core assembly. This tracking may be maintained throughout the life of the core assembly and during disposal processing via the plant's radioactive inventory surveillance program. Flow tests may also be performed on the core assembly on the inspection platform as a final go / no-go test of the assembly.

[0071] (Containment and conditioning of new core assemblies (prior to refueling outages)) A clean, uncontaminated conditioning cell may be prepared for the core assembly, for example, by opening a floor valve and using a jib hoist 600 and grapple tool to pull or remove a floor access plug. The hoist 600 transfers the floor plug to a storage location during loading. The inspected and logged core assembly 500 may then be transferred into the conditioning cell 604 using the jib hoist 600 and grapple tool. Each core assembly 500 position within the conditioning cell may be filled by rotating a carousel to align with the floor valve opening. Once the carousel is filled and the assembly 500 has been conditioned to refueling temperature under an inert argon environment, the valve may be closed. In some cases, the carousel capacity may be designed to hold one-third of a core batch (e.g., 15 assemblies in some embodiments) to allow batch conditioning with intermediate BLTC transfer to the EVST. The conditioning cell may not be intended to handle a core assembly that has decay heat originating from the nuclear reactor.

[0072] According to some embodiments, conditioning is a feed and bleed process. The conditioning cell begins with a feed-and-bleed process. The initial air and moisture content of the conditioning cell results in a dry, completely inert argon environment. Electrical heating and circulation may then be used to gradually raise the argon environment to the reactor's refueling temperature of approximately 400°F. In some cases, other forms of heating may be utilized. For example, the argon gas may be passed through a heat exchanger or may be heated using heat generated in the reactor core. The inspection, loading, and conditioning process may be repeated until an outage batch (e.g., up to 45 core assemblies or more) has been conditioned. This process may be performed prior to a refueling outage to ensure that the core assemblies are sufficiently conditioned and stored in the EVST prior to reactor shutdown. Multiple reactors using the same conditioning cell and EVST may have staggered conditioning times and shutdowns may occur at staggered times so that the conditioning cell and EVST can be utilized for multiple reactors.

[0073] An overhead crane may be used to install the floor isolation valves and their associated adapters onto the EVST. A shield plug handling cask may be mated to the floor isolation valves to pull and remove the shield plugs, providing access to the carousel for loading. The floor isolation valves may be closed, and the shield plugs may be removed and stored by the crane and shield plug handling cask. The EVST may be brought to an inerted refueling state to receive a new core assembly.

[0074] (e.g., transfer of BLTC to EVST (prior to refueling outage)) The BLTC may mate with the conditioning cell floor valve during a refueling condition, allowing up to three or more core assemblies 500 to be sequentially picked up from the carousel and transferred into the cask. The BLTC continues to transfer core assemblies from the conditioning cell to the EVST carousel until a full refueling batch is staged for outage. As each core assembly is placed in the EVST, the tracking database is updated, and all information necessary to establish the planned refueling outage sequence is verified and uploaded to the refueling control center. During an outage, the EVHM may replace a new core assembly in the EVST with a spent core assembly coming from the reactor according to the established refueling sequence from the refueling control center.

[0075] In some cases, the BLTC is a rail-mounted, freestanding, seismically qualified cask with a vertically translating isolation valve. The BLTC may have heating and / or cooling capabilities to handle either fresh or spent fuel core assemblies. The BLTC may have a centerline travel path that accesses the conditioning cell, EVST, and / or pool immersion cell through floor isolation valves.

[0076] (e.g., reactor shutdown and shutdown preparation methodologies) According to some embodiments, the nuclear reactor is prepared for a post-shutdown refueling. According to some embodiments, a forced flow pump may be fixed within the reactor. Natural circulation cooling brings the reactor to a refueling temperature of approximately 400°F. This refueling temperature is provided as an example; of course, other refueling temperatures may be applicable to other types of nuclear reactors. As used herein, the terms "about" and "approximately" may, in some examples, indicate a variability of up to ±5% of the associated numerical value, such as a variability of up to ±2%, or a variability of up to ±1%.

[0077] The ASME boundary flange may be removed from the refueling port. The main hook of the RB overhead crane may then move the refueling port transfer adapter from its storage location on the refueling floor to the refueling port. The transfer adapter may be installed on the refueling port, followed by the associated floor isolation valve on the refueling floor. Optionally, the transfer column assembly may be tested, inerted, and / or heated to refueling temperatures. The transfer adapter may also have cooling capabilities in case the fuel assembly remains between the cask and the reactor. In some cases, the transfer adapter loading is supported by the civil structure of the reactor building refueling floor rather than the reactor head. In some cases, the transfer adapter is shared among multiple reactors (e.g., two, three, four, or more reactors) with the storage location supporting offset outage schedules.

[0078] In the EVST, the shield plug transfer cask may be mated to the EVST floor isolation valve by the RB crane. The cask isolation valve and floor isolation valve may be opened to access the EVST shield plug. The plug may be grasped by a cask hoist and elevated into the cask. After the plug is elevated, both valves may be closed, and the EVST shield plug may be transported to a storage location in the EVST carousel or to another floor structure. The floor isolation valve may be an inert EVST boundary for refueling port plug transfer.

[0079] At the reactor, the inerted shield plug transfer cask may be mated to a transfer adapter and / or floor valve by a crane RB. The cask isolation valve and floor isolation valve may be opened to access the reactor's refueling port plug. The plug may be grasped by a cask hoist and lifted into the cask. Both valves may be closed, and the refueling port plug may be transported to an EVST plug storage location or other location for portable glove box maintenance. The shield plug cask may also have storage on the RB refueling floor, and in some cases, have seismic support.

[0080] The control rod drive lines are separated from the control rod assemblies (CRAs) in the core to allow rotation of the rotating plug and IVTM for refueling. In some cases, the control rod core assemblies are separated using a tool actuated through the control rod drive mechanism above the reactor head. Alternatively, new CRDM designs will allow for remote separation and lifting of the drive lines to allow movement of the rotating plug and IVTM.

[0081] A rotating plug jack may lift the plug from its reactor head ledge seal to allow it to rotate. The power and control cables for the rotating plug and IVTM may be reconnected to unlock the IVTM driveline. The IVTM may be calibrated by position checks at up to six or more gauging locations around the core periphery.

[0082] A transfer station lift directly below the refueling port may be cycled to raise and lower the core assembly transfer basket between a level slightly above the reactor sodium level and a position the length of the core assembly above the core. The lift may be driven by a rotating shaft coming through the reactor head or refueling port with a cover gas seal. In some cases, the lift moves the core assembly from its side entry basket to a height where the IVTM can grasp the core assembly.

[0083] In some embodiments, once the IVS position of the core assembly is confirmed to be empty, the process initiates a refueling operation. A verified refueling sequence for the core assembly movement may be confirmed within the integrated refueling control system for the EVHM, rotating plug, IVTM, and EVST carousel.

[0084] (EVHM, Transfer Station Lift, IVTM, Reactor Core and Core Assembly Transfer between IVS) See FIG. 7. According to some embodiments, EVHM 700 is a seismically qualified cask support structure that is mounted on rails and handles all core assembly transfers during an outage. The EVHM may be designed so that cask centerline movement is precisely coordinated with both the reactor refueling port and the EVST access port. In some cases, EVHM 700 includes a grapple drive system 702, a transporter 704, and a control cab 706. Control cab 706 may include controls for operating transporter 704 and grapple drive system 702.

[0085] The EVHM may further include a cask 710. In some cases, the cask 710 is shielded. The cask may have a movable bottom-entry isolation valve 712 and may further include inerting, heating, and cooling capabilities for the fresh and spent core assemblies. The EVHM 700 may further include a blower 714 and / or an exhaust system 716 for circulating air or some other gas. The EVHM cask grapple may be a typical top-entry design and may have three to four (or more) fingers that engage with structures on the core assembly head. The EVHM cask may include a refueling control interface for interlocking between the EVHM cask, the transfer adapter floor valve, the transfer station lift, and the EVST carousel.

[0086] In use, for example, during an outage, the EVHM 700 mates with the EVST floor valve and can individually grasp and raise up to three or more core assemblies into its cask 710. The cask 710 can be inerted, shielded, and / or heated. The EVST carousel can be rotated as needed so that sequential core assembly locations are selected for refueling. The EVST is isolated by closing the EVHM cask isolation valve and the EVST floor valve. The EVHM 700 may further include an indexing system 718 for accepting multiple core assemblies.

[0087] The EVHM 700 may be moved to the refueling port transfer adapter and mated with its floor valve. The transfer path into the reactor may be verified to be inerted and heated to the refueling condition prior to any valve operation.

[0088] The core assembly grasped within the EVHM 700 may have its identity verified to be compatible with the refueling sequence. When the inert refueling conditions are equal across the transfer adapter floor valve and the cask isolation valve, both valves may be opened for transfer passage into the reactor. The EVHM 700 hoist may lower the core assembly from the cask into a lift station basket in the cover gas region.

[0089] The lift station may be positioned within the sodium below the refueling port and may lower the core assembly through the refueling port thimble to a position the core assembly length above the reactor core. The transfer station lift may have a refueling control interlock with the EVHM hoist / grapple and the IVTM. The lift station basket may have a side entry design to limit the required vertical movement of the IVTM. The lift station assembly may be vertically removable through the reactor refueling port for any necessary maintenance or replacement.

[0090] The IVTM may perform core and IVS transfers to complete the refueling outage sequence (e.g., from the core to the IVS, from the IVS to the transfer station lift, and then from the transfer station lift to the core). In some cases, depending on the transfer station design, the IVTM grapple head may move horizontally (sideways) into a slotted thimble above the core assembly in the transfer station basket. In some cases, the IVTM grapple aligns with the center of the core assembly and then lowers to grip the inner diameter. The IVTM grapple may then rise vertically to unseat the core assembly head from the basket. The IVTM grapple may then translate the gripped core assembly horizontally out of the side entry basket. This process may be repeated by the IVTM so that the core assembly is retrieved and placed into the lift station basket.

[0091] The IVTM may perform core and IVS transfers to complete the refueling outage sequence (e.g., from the reactor core to the IVS, from the IVS to the transfer station lift, and from the transfer station lift to the reactor core). The IVTM may be installed on the reactor's rotating plug and may have a horizontally moving pantograph carrying a grapple head with an extension configuration for raising and lowering the core assembly. The IVTM grapple may be centered at the core, IVS, or transfer station location by rotation of the rotating plug, rotation of the IVTM, and / or extension of the pantograph. In some cases, the IVTM grapple is a top-entry design with three to four fingers that engage the inner diameter of the core assembly head. However, the IVTM grapple can be configured to have any suitable design. The IVTM grapple head may also have rotation capability to orient the hexagonal outer shape of the core assembly for core insertion. The reactor's UIS may have a slot that allows the IVTM to refuel in the centerline region of the core. The mapped core assembly location within the reactor may be stored in the machine's computer-controlled memory, enabling refueling through an automated sequence. The automated sequence may be confirmed by an operator. The IVTM may have refueling control interlocks with the control rod drives, rotating plug, and / or transfer station lift. The in-core portion of the IVTM may be replaceable by pulling the assembly through a transfer adapter into a cask on the refueling floor.

[0092] According to some embodiments, to initiate a refueling sequence, the IVTM moves the spent core assembly from the core to an open IVS location, then picks up the new core assembly from the transfer station basket and places it into the open, sequenced core location. The lift station may operate to raise the core assembly head to a gripping height in the cover gas region. The EVHM cask isolation valve and transfer adapter floor valve may be opened, and the cask hoist may lower to grip the core assembly from the transfer station lift basket. The core assembly coming from the IVS storage may have a decay heat of less than 1.2 kW (e.g., two 18-month cycles) to be transferred in the EVHM.

[0093] The cask hoist may raise the spent core assembly into a shielded portion of the cask above the isolation valve. A sodium drip pan may rotate below the assembly to capture dripping sodium. In some cases, a passive or active cooling configuration for the cask may be established to remove core assembly decay heat. The identity of the core assembly may be confirmed and / or recorded, for example, by a cask camera viewing the top of the core assembly. The cask hoist may release the spent core assembly in the cask holding position for transfer to the EVST. This process may be repeated according to the refueling sequence for other core assemblies until the EVHM is filled with one or more spent fuel assemblies.

[0094] The EVHM cask isolation valves and transfer adapter isolation valves may be closed, and the EVHM may be moved from the refueling port to the EVST for unloading into the EVST carousel. This refueling process is repeated according to the refueling sequence for all core assemblies in the outage batch. In some cases, the outage batch may be 45 assemblies. However, of course, in other embodiments, any suitable number of core assemblies may be utilized. In some cases, fewer than all of the core assemblies are replaced at a given time. The IVTM may perform independent in-core fuel, reflector, or shield shuffling or rotation in the outage sequence in parallel with the EVHM movement so that core assemblies are offloaded and reloaded at the EVST.

[0095] (Transfer of EVHM core assembly to EVST) After the EVHM is loaded with spent core assemblies, the EVHM may be separated from the refueling port floor valve and moved to the EVST. The EVHM cask isolation valve may be mated with the EVST floor valve, which may be opened. Each spent core assembly in the EVHM cask may be grasped and placed in an ordered storage position on the EVST carousel. Fuel assemblies may be placed in the outer rows of the carousel for maximum decay heat removal, and any non-fuel assemblies may be placed in the inner ring of the carousel. The storage position of each core assembly may be recorded and tracked by the integrated refueling system control. The EVHM cask grapple, hoist, and isolation valve may have refueling interlocks with the EVST floor valve and carousel drive.

[0096] The EVST may be used as a short-term storage point during a refueling outage. After the outage, the BLTC may transfer the core assembly to the spent fuel processing and waste disposal cycle.

[0097] (Example: Transfer of BLTC core assembly to FSF) After reactor shutdown, the BLTC may move over the EVST and engage with the floor valve. The carousel may be rotated to the appropriate core assembly, and the cask isolation valve and floor isolation valve may be opened. A cask hoist and grapple may be lowered into the EVST, and the core assembly may be grasped and raised into the cask. The cask may be secured by closing the cask isolation valve and floor valve. The cask isolation valve may then be raised to separate the BLTC for movement on its rails. In some cases, the BLTC may have a transfer capacity equal to the EVHM. In some cases, the transfer capacity is up to three core assemblies at a time. The BLTC may be a seismically qualified, rail-mounted cask that operates in both the reactor building and / or the FSF. The BLTC may be used for multiple reactors and may support one, two, three, four, or more reactors in an expanded configuration.

[0098] (e.g. external sodium removal) This paper describes a rapid method for transferring irradiated core assemblies directly into a water-filled spent fuel pool for long-term disintegration and wet cask loading, as opposed to conventional wet cask loading methods that require long periods of time (e.g., more than 2 hours, more than 4 hours, more than 6 hours, more than 8 hours, more than 10 hours, more than 15 hours, more than 18 hours, or more than 20 hours). Figures 8A and 8B show the pool immersion cell, underwater storage rack, and wet cask loading approach. The described process is highly efficient and significantly faster than conventional processes. Long-term underwater fuel storage has the advantage of extensive licensing and operational experience in highly reliable light water reactors.

[0099] Preparation for direct pool immersion relies on two primary factors. First, inert gas is vented downward onto the core assembly when it is removed from the reactor core, or in the pool immersion cell, or both. Second, the assembly may undergo a wet inert gas reaction cycle in the pool immersion cell, followed by complete flooding of the core assembly. After the flooding process, the core assembly may be transferred to the main portion of the pool for long-term storage. This process significantly reduces the 18-24 hours typically required in conventional processes because the assembly does not undergo drying and inerting but instead goes directly to the pool and is not handled again by the BLTC.

[0100] See Figures 8A, 8B and 9. According to some embodiments, detailed pool immersion process steps 900 may include some of the following:

[0101] At block 902, the core assemblies may be handled dry in the inert environments of the EVHM, carousel, and BLTC, which will limit residual sodium remaining after their removal from the EVST.

[0102] The spent core assembly may first be transferred, for example by a BLTC, to a dry, inertized pool immersion cell 802 .

[0103] The BLTC may mate with a submerged cell floor valve 804 and lower the core assembly into a core assembly elevator 806, which captures the core assembly 500 with a clamping device 808, for example, just below the upper handling socket.

[0104] After the load is transferred to the clamping device, the BLTC may release its grapple and raise its hoist, and the cask valve and floor valve may be closed.

[0105] Within the submerged cell 802, the retractable arm and nozzle 810 may move over and mate with the core assembly head, and a cell vent path may be established through the submerged cell 802 to the pool water.

[0106] At block 904, an inert gas flow may be established through and / or above the assembly 500. Optionally, the inert gas flow may be metered to ensure that gas flows freely through the assembly.

[0107] At block 906, the moisture content in the inert gas stream may be gradually increased to about 100% into the gas stream, thereby reacting any remaining sodium.

[0108] After the moisture content reaches 100%, the flow of gas and moisture may be stopped and the retractable arm and nozzle assembly 810 may be retracted from the core assembly 500.

[0109] At block 908, the cell isolation valve 812 may be opened at the bottom of the cell, allowing flooding and covering of the assembly 500.

[0110] Elevator 806 may then lower core assembly 500 into a movable trolley rack 814 on the bottom of the pool.

[0111] The elevator clamp device 808 may release the core assembly seated on the movable trolley rack 814 and lift it back into the cell 802 .

[0112] In block 910, the core assembly 500 may be moved by a movable trolley rack 814 into a main pool 820. In the main pool 820, a simple fuel handling machine 822 may grasp the assembly 500 and transport it into a designated top entry storage rack location.

[0113] The sodium reaction process may be repeated for shut down batches of fuel and non-fuel core assemblies.

[0114] The core assembly may continue its decay in the fuel racks for a suitable length of time (e.g., 10 to 15 years in some cases) and be cooled by the pool until the decay heat requirements for the wet cask loading process are met.

[0115] As an optional step, an overhead crane may transfer the inner cask container 824 into the cask pit for wetted pool loading.

[0116] Simple fuel handling machinery 822 may grasp the collapsed core assemblies and transport them to a submerged cask 824 .

[0117] The process may be repeated until inner cask 824 is filled, after which inner cask 824 may be capped and lifted by an FSF crane to the fuel facility floor.

[0118] The inner cask may be drained, dried, and / or completely inerted, for example, with helium.

[0119] The FSF crane may assemble the final dry cask shielding package and place it onto the transporter.

[0120] Spent fuel dry casks may be transported to a site storage pad. Waste casks may be filled with non-fuel assemblies and shipped to a suitable waste repository in a similar or identical manner.

[0121] FIG. 10 shows a sample process flow for pool storage and wet cask loading. In block 1002, the core assembly is transferred to a pool immersion cell. In some cases, the pool immersion cell has sufficient volume so that there is little or no risk of pressure buildup due to hydrogen generation. In block 1004, sodium is reacted with water, for example, as described herein. In some cases, gas is passed over and / or through the core assembly to first facilitate removal of any sodium within the core assembly. The gas may also be used for leak detection. For example, leaks may be detected by testing the gas for fission products after it has passed through the core assembly. The water content of the gas may be gradually increased, for example, by adding steam to the gas, to react with the remaining sodium and create a passivating layer of sodium hydroxide to encapsulate any remaining sodium on or within the core assembly.

[0122] At block 1006, any failed assemblies are immersed in a pool, canned, and secured. In some cases, the failed fuel assemblies are first canned and secured, and then introduced into the spent fuel pool. At block 1008, the core assemblies are immersed in a pool of water and transferred to storage racks within the pool. This may be accomplished by using pool handling machinery.

[0123] At block 1010, the dry cask is loaded into the pool with the core assembly using pool handling machinery. In some cases, the core assembly is loaded after about 10, 12, or 15 years of residence time in the pool.

[0124] At block 1012, the canned failed fuel assemblies are transported for cask loading, which may occur prior to loading the core assembly into the cask.

[0125] Fuel core assemblies are identified for waste tracking and cask closure at block 1014. Non-fuel core assemblies are identified for waste tracking and waste reduction at block 1016 and transferred to waste casks in the pool.

[0126] At block 1018, the non-fuel assembly casks are closed in the pool. At block 1020, the casks (both dry casks and waste casks) are lifted, dried (e.g., using helium), and sealed. At block 1022, the casks are loaded onto a cask transporter.

[0127] At block 1024, the dry cask is transported to a site pad for storage. At block 1026, the non-fuel containing waste cask is sent for long-term waste disposal.

[0128] (e.g., maintenance strategies for infrequently serviced sodium wetted equipment) Transfer adapters may be installed by crane between the refueling floor and the reactor head / rotating plug for each piece of equipment to be individually removed or installed. A large-aperture maintenance floor valve may be placed on top of the associated transfer adapter. Multiple transfer adapters may be inerted, for example with argon, for equipment transfer. Large component transfer casks may be installed onto the floor valves by RB cranes, fleet crane assemblies, or temporary fleet cask carriers.

[0129] Equipment may be hoisted through transfer adapters into large component casks, which may be handled by RB cranes, fleet cranes, or fleet cask carriers for transport to maintenance / waste handling buildings for off-site transport.

[0130] (Example: handling damaged fuel) If a failed fuel assembly (failed pin) is routed for disposal, it may be processed through a pool immersion cell, and the assembly may be canned in a PIC before being stored in the SPF until the wet cask loading process begins. A failed fuel assembly may have cracks in the cladding that allow communication between the interior of the fuel pin and the external environment. In some cases, a detection system can determine whether fission products are present in the inert gas used to remove sodium from the fuel assembly. In some cases, gamma spectroscopy may be used to detect neutrons emanating from the fuel assembly, which can be used to detect a failed fuel assembly. In some cases, the inert gas is pressurized to aid in leak detection.

[0131] (e.g., additional use of FSF) The FSF may provide work floor space for new fuel receipt and all spent fuel processing, and it may provide crane and large cask floor space for all non-routine reactor maintenance and removal of components such as the refueling port lift, IVTM, control rods, electromagnetic pumps, intermediate heat exchangers (IHX), and sodium traps.

[0132] Additional floor space may also be provided for cask, reactor component break-down maintenance, or radiological decontamination operations, or for shutdown support, and may be used for mock-ups of critical reactor operations or training evolutions.

[0133] (e.g. sodium removal machine) Referring to Figure 11, a pool immersion cell (PIC) 1100 is illustrated, showing an exemplary location of a sodium removal machine 1102, according to some embodiments. In many sodium fast reactors (SFRs), "primary" sodium from the core is removed from the removed core assembly to reduce potential fire hazards and facilitate more convenient operation and storage practices. While the structure for removing sodium varies from reactor design to reactor design, particularly preferred system and method embodiments are described herein.

[0134] In many cases, pressurized circulation of a liquid-laden inert gas is followed by a water flush with a final drying step. In many conventional designs, the equipment required to accomplish this involves an entire controlled atmosphere room, or in some cases, a covered stationary vessel into which the core assembly is inserted, processed, and then removed. Alternative methods that have been proposed include gradually immersing the core assembly in a bath containing water, which reacts with the residual sodium. In some cases, conventional approaches have proposed using CO2 and / or alcohol cleaning agents instead of water-laden gases.

[0135] 11 , a sodium removal machine 1102 removes primary sodium from a wet core assembly removed from a nuclear reactor and introduces the core assembly into a spent fuel pool 1104. The spent fuel pool 1104 may contain spent fuel pool racks 1106 (SFP racks) for storing the core assemblies and one or more dry storage casks 1108 for storing the core assemblies after an appropriate cool-down period in the SFP racks. The illustrated and described machine is a compact, safer, more efficient, and lower-cost alternative to conventional sodium removal equipment and methods.

[0136] According to some embodiments, the sodium removal machine 1102 is comprised of three main assemblies: a receiver 1110, a cleaning bin (not shown), and an elevator 1114. The receiver is configured to mate with a fuel loading floor valve 1116. The receiver houses one or more fluid process connections. The receiver may be static. The receiver is coupled to the fuel loading floor valve at one end and selectively coupled to the cleaning bin at the opposite end. According to some embodiments, the cleaning bin is sized to receive a core assembly therein. The core assembly may be any assembly configured to be removed from the reactor core. Core assemblies may include, but are not limited to, spent fuel assemblies, partially spent fuel assemblies, reflector assemblies, parent fuel assemblies, reactivity control structures, and neutron absorber assemblies, among others. The terms core assembly and core component may be used interchangeably herein in that the cleaning bin may receive the core assembly or core component without modification to the cleaning bin.

[0137] In some cases, the cleaning bin is only slightly longer in diameter than the core assembly. For example, the diameter of the cleaning bin may be 5%, 10%, 15%, 20%, 33%, or 50% larger than the diameter of the core assembly. For example, if the hexagonal core assembly has a cross-sectional dimension of approximately 6 inches from flat to flat, the diameter of the cleaning bin may be 7", 8", 9", 10", 12", or larger. The cleaning bin may be longer than the fuel assemblies. The cleaning bin may include one or more fluid inlets near the top end for introducing fluid and a collection space near the bottom for collecting and removing the cleaning fluid. The cleaning fluid may be recirculated from the bottom of the cleaning bin to the top of the cleaning bin during a twice-through cycle, or a recirculation cycle. The cleaning fluid may eventually be removed from the cleaning bin and analyzed for the continued presence of sodium or other components.

[0138] According to some embodiments, the length of the cleaning canister is longer than the length of the core assembly so that the core assembly can fit completely within the cleaning canister. In some cases, the cleaning canister is only slightly longer than the core assembly. In some cases, the length of the cleaning canister is 10%, 20%, 30%, 50%, or more than the length of the core assembly. In other words, in some cases, the core assembly occupies more than half of the volume of the cleaning canister, and in some cases, the core assembly occupies more than 60%, or more than 70%, or more than 80%, or more than 90% of the volume of the cleaning canister.

[0139] According to some embodiments, the sodium removal machine 1102 is configured to clean the primary sodium from the removed core assembly and transfer the removed core assembly to a spent fuel pool by enclosing the removed core assembly in a cleaning vessel, introducing a cleaning fluid, and then lowering the removed core assembly into the spent fuel pool via the elevator 1114. In some cases, the cleaning fluid may be water or an inert gas containing water.

[0140] 12 shows the sodium removal machine 1102 from below, showing the receiver 1110, cleaning bin 1112, and elevator 1114. In some cases, the receiver 1110 remains in place in the ceiling of a pool submerged cell that forms the floor of the fuel transfer area. The elevator 1114 is configured to mate with the cleaning bin 1112 and lower it into the spent fuel pool 1104. In this manner, the cleaning bin 1112 can be sealed with the core assembly inside the cleaning bin 1112 and introduced into the spent fuel pool.

[0141] See FIG. 13. A bottom loading transfer cask (BLTC) 1302 delivers the removed core assembly from the core to the fuel loading floor valve. The BLTC mates with the fuel loading floor valve from above to form a seal for handing over the removed core assembly. Below the fuel loading floor valve, a receiver is coupled to the fuel loading floor valve, which is further coupled to a cleaning bin. Once the BLTC is coupled to the fuel loading floor valve, the removed core assembly can be lowered through the fuel loading floor valve, through the receiver, and into the cleaning bin. The cleaning bin 1112 may remain coupled to the receiver during the core assembly cleaning process. The cleaning bin may then be lowered into the spent fuel pool, and the cleaning bin 1112 may be transferred to a PIC trolley. The PIC trolley can maneuver the core assembly to be stored in the SFP rack. In some cases, the cleaned core assembly is removed from the cleaning bin before being stored in the SFP rack. In some cases, when operational needs necessitate emptying the elevator 1114 and trolley, the cleaning container 1112 may also be removed and stored separately.

[0142] Referring further to FIG. 14 , a partial cutaway view of the BLTC 1302 and receiver 1110 is shown. The BLTC 1302 may be a mobile transfer unit that receives removed core components in the EVST 404. The BLTC 1302 may transport the core components to the fuel loading floor and may be positioned above the fuel loading floor valve 1116. The BLTC 1302 may couple with the fuel loading floor valve 1116 and then lower the core assembly through the fuel floor valve into a waiting cleaning bin. The cleaning bin captures the core assembly, and the fuel loading floor valve closes. The BLTC may be moved and / or may retrieve another core component.

[0143] The BLTC mates with and forms a seal with the fuel loading floor valve 1116. Similarly, the fuel loading floor valve 1116 is coupled and sealed to the receiver 1110. In some cases, the cleaning vessel 1112 is physically and fluidically coupled to the receiver 1110, and cleaning fluid can be introduced into the receiver and thereby into the cleaning vessel 1112. In some cases, an inert gas containing water is introduced into the cleaning vessel to clean sodium from the core assembly. For example, in the case of a gas containing water, the water reacts with the sodium to produce sodium hydroxide and hydrogen gas. In some cases, the inert gas is argon, but may be any other suitable gas containing water.

[0144] 15 illustrates a sodium removal machine elevator 1114, according to some embodiments. The elevator 1114 includes a frame 1502. The frame 1502 defines a track. The elevator 1114 is configured to lower and / or raise a cleaning receptacle 1112 along the track. The elevator may transport the cleaning receptacle 1112 through any suitable structure, including, but not limited to, a pulley, a chain, a motor, a wheel, a sheave, a power screw, or a gear, among others.

[0145] The cleaning receptacle 1112 may be secured to the elevator 1114 by a carriage. The carriage may include any suitable mechanism. For example, the suitable mechanism may be a clamp, an interference fit, a grapple, a hook, a clip, a magnet, a slot, a keyway, or any other suitable structure for securing the cleaning receptacle 1112 to the carriage. In some cases, the cleaning receptacle 1112 is releasably secured to the elevator 1114 such that the cleaning receptacle can be selectively attached to and detached from the elevator 1114. In some cases, the cleaning receptacle is releasably secured to the elevator 1114 by a handling feature. In some cases, the cleaning receptacle 1112 is releasably secured to the elevator 1114 by a basket having handling features that mate with the elevator carriage. The handling features may be cooperating slots that receive protrusions to couple the cleaning receptacle 1112 with the elevator 1114. The elevator 1114 is configured to move between an upper position where the cleaning bin 1112 is coupled to the receiver 1110 and a lower position where the cleaning bin 1112 can be placed into a PIC trolley.

[0146] Referring to Figure 16, elevator 1114 is shown descending from an upper position to a lower position. A cleaning vessel 1112 is shown, along with a PIC trolley 1602 in a position to receive the removed core component within cleaning vessel 1112. In some cases, the core component is cleaned of residual sodium while coupled to receiver 1110 in the upper position, and only after cleaning is it disconnected from receiver 1110 and lowered to PIC trolley 1602.

[0147] Referring further to FIG. 17 , as the elevator 1114 approaches or reaches the lower position, the handling feature may disengage from the cleaning receptacle 1112 and transfer the cleaning receptacle 1112 to the PIC trolley 1602. It should be understood that the PIC trolley is one of several ways to receive the cleaning receptacle 1112 into the pool immersion cell, and that other methods of handling the cleaning receptacle 1112 and / or the removed core component are equally applicable. For example, a crane may be used to receive the removed core component and place it into the pool immersion cell, or further place it into a PIC rack in the spent fuel pool. In some cases, a crane is used in conjunction with the PIC trolley. For example, the PIC trolley may receive the cleaning receptacle 1112 from the elevator 1114 and then transport the cleaning receptacle 1112 to an area adjacent to the SFP rack 1106 ( FIG. 10 ). A crane may then retrieve the cleaning canister 1112 from the PIC trolley 1602 and place it in the SPF rack 1106 for storage in the spent fuel pool. In some cases, the removed core component may be removed from the cleaning canister 1112 and stored in the spent fuel pool for an appropriate cool-down period. In embodiments in which the removed core component is removed from the cleaning canister 1112 for storage, the PIC trolley 1602 may transport the cleaning canister 1112 to the elevator 1114, where it may be coupled to the elevator 1114 and raised to an upper position on the elevator 1114 to await the subsequent removed core component.

[0148] 18 and 19 . The elevator 1114 is shown with a carriage 1802 and its handling feature 1702. According to some embodiments, the handling feature releases the cleaning bin 1112 when the carriage 1802 moves over the elevator frame 1502. This may be achieved, for example, by the carriage 1802 releasing the cleaning bin 1112 as a result of mechanical interference between the carriage 1802 and a portion of the frame 1502. In some cases, a sensor may be used to sense when the carriage 1802 is near or at the lower limit of travel, and a controller may send a signal to the carriage 1802 to release the cleaning bin 1112 into the PIC trolley. In some cases, the handling feature is completely passive and requires no actuation to release the cleaning bin 1112 from the carriage 1802. According to some embodiments, the handling feature includes a strong-back rib with a bearing. The bearings may be permanently affixed to a basket that holds the cleaning receptacle. The bearings may be configured to slide down into a T-slot affixed to the elevator carriage. The basket may be positioned at the end of the trolley's travel, with its ribs directly above the T-slot. As the elevator carriage rises, it captures the first bearing seated inside the T-slot and eventually bottoms out. This motion continues upward, lifting the basket (along with the cleaning receptacle) off the trolley.

[0149] FIG. 20 shows the cleaning bin 1112 released from the carriage and transported by the PIC trolley 1602. In some cases, the PIC trolley 1602 may ride on rails 2002 and transport the cleaning bin 1112 from a first position to a second position. In some cases, the first position may be below the elevator 1114, and the second position may be adjacent to an SFP rack in the spent fuel pool. The PIC trolley 1602 may be moved between the first and second positions by a motor, a pulley, a pull-pull mechanism, wheels, or some other structure that allows the PIC trolley 1602 to move between the first and second positions. In some embodiments, the PIC trolley 1602 may not be constrained by a set trajectory, but rather may move freely within the spent fuel pool and may be controlled by one or more sensors, one or more motors, and / or one or more controllers.

[0150] In some cases, a cleaning container may replace a damaged fuel canister. The dimensions of the damaged fuel canister may be selected so that it is compatible with the cleaning container and shares PIC equipment. For example, the damaged fuel canister may engage all of the equipment in the PIC (e.g., the PIC trolley, elevator 1114, SFP rack 1106) (FIG. 10), as well as any cranes or hoists used to transport the cleaning container. Thus, in some cases, the PIC may be used as a canister welding and loading station. After welding the canister seams, the damaged fuel canister can use the same elevator and trolley as the cleaning container, and the damaged fuel canister may be stored in the SFP.

[0151] FIG. 21 shows a partial cross-sectional view of an embodiment of a receiver 1110 having an associated cleaning receptacle 1112. The receiver 1110 may be composed of multiple pieces, such as a receiver body 2102 mating with a receiver flange 2104. The receiver flange 2104 may be engaged with an outer flange 2106. The outer flange 2106 is formed in the fuel loading floor and is designed to carry the load of the cleaning receptacle 1112 transmitted through the elevator frame 1502 (not shown) and the receiver flange 2104. A receiver access plate 2107 may provide access to the receiver flange 2104 and / or the outer flange 2106, as well as other components of the receiver 1110, as desired. A receiver bore 2108 may be centrally located through the receiver 1110. The receiver bore 2108 may provide a path for retrieved core components to pass through the receiver 1110 and into the cleaning receptacle 1112.

[0152] For example, the core assemblies may pass from a BLTC (not shown) through a fuel loading floor valve and a receiver 1110 into a cleaning vessel 1112. One or more supply and return lines 2112 may provide fluid communication with the receiver and the interior of the cleaning vessel 1112. For example, when the cleaning vessel 1112 is coupled to the receiver 1110, there may be a mechanical connection to keep the cleaning vessel 1112 in proximity to the receiver 1110, and there may also be a fluid connection to deliver one or more fluids to the receiver 1110, for example, via the supply lines 2112, and enter the cleaning vessel 1112. In some cases, the fluids entering the cleaning vessel 1112 are drawn from the cleaning vessel 1112 by one or more vessel drain tubes 2114. In some cases, a process agent return port 2116 allows fluids used to clean one or more core assemblies 2110 to be returned for further processing or cleaning fluids. As described, the fluid may be a liquid, gas, or combination thereof suitable for cleaning the core assembly 2110 before it is moved into the PIC and spent fuel pool. Of course, the described embodiment is provided by way of example only, and the specific components, interfaces, and structures may take any of a variety of configurations that embody the concepts described herein.

[0153] 22 and 23 show the upper and lower areas, respectively, of the cleaning vessel 1112. The upper area 2202 may include structure that cooperates with the core assembly 2110 to retain the core assembly 2110 within the cleaning vessel 1112. In some cases, the core assembly 2110 has a longitudinal axis, and the structure maintains the longitudinal axis of the core assembly 2110 substantially aligned with the axis of the cleaning vessel 1112. The structure may include one or more of a protrusion, groove, boss, pocket, seal (e.g., an inflatable seal or ring seal), clamp, lock, cam, or other structure that may retain the core assembly 2110 within the cleaning vessel 1112.

[0154] The lower area 2302 of the cleaning receptacle 1112 may include a structure to support the weight of the core assembly 2110. The weight-supporting structure may include one or more of a shelf, a protrusion, a ring, a hole in a plate, a clamp, a cam, or other structure to support the weight of the core assembly 2110 within the cleaning receptacle 1112. In some cases, the core assembly 2110 may include a nozzle 2304 that fits into a receptacle formed in the cleaning receptacle 1112. The receptacle may include a hole or recess configured to receive the nozzle 2304 and maintain the nozzle 2304 substantially aligned with the longitudinal axis of the cleaning receptacle 1112. In some cases, one or more seals allow a pressure differential between the area below the nozzle 2304 and the area above the nozzle. Additionally, providing a seal near the nozzle 2304 facilitates the passage of process gas through the interior of the core components.

[0155] The lower area 2302 of the cleaning vessel 1112 may include a chamber 2306 (e.g., a plenum chamber) for collecting fluids, effluents, and other materials that may be introduced into the cleaning vessel 1112 or removed from the core assembly 2110. The chamber 2306 may have a return line disposed therein for returning the collected materials to the top of the cleaning vessel 1112 or to a location external to the cleaning vessel 1112.

[0156] 24 and 25, cross-sectional views of the receiver 1110 and cleaning receptacle 1112 are shown. The receiver 1110 defines a bore through which a core assembly can be inserted into the receiver 1110. As described with other embodiments herein, a process agent supply 2402 can provide one or more fluids into the cleaning receptacle 1112. One or more process agent returns 2116 can be provided to withdraw fluids and other materials removed from the core assembly 2110. In some cases, the cleaning receptacle 1112 is sealed to the receiver 1110 by, for example, one or more seals 2406. The seals 2406 can be any suitable seal, including, for example, an O-ring seal, an inflatable seal, an annular seal having an alternative cross-sectional shape, or any other suitable type of seal that inhibits passage of introduced fluids between the receiver 1110 and the cleaning receptacle 1112. As a result, the seal urges the introduced fluid through the cleaning receptacle 1112 and around and through the core assembly 2110. Once the core assembly 2110 is placed in the cleaning receptacle 1112, the fuel loading floor valve may be closed, and the cleaning receptacle 1112, receiver 1110, and the fuel loading floor valve may cooperate to form a closed boundary. In some cases, the closed boundary may be pressurized, such as with a liquid, gas, or a combination thereof, and may contain a pressure that acts to assist in circulating the cleaning fluid around and through the core assembly. Additionally, a pressurization system may urge the cleaning fluid through the cleaning receptacle 1112 and out the return line 2404.

[0157] In some cases, the fluid connections into the receiver 1110 are static. This is primarily because the receiver is static and can be configured to remain in place during loading, cleaning, and transport of the core assembly as it progresses from the reactor core to a spent fuel pool for storage. The fluid connections may be removable as desired, for example, for cleaning or maintenance. Process fluid may be introduced into the top of the receiver, for example, through a process agent inlet 2402, and travel down through the core assembly to a lower plenum chamber 2306 at the bottom of the cleaning vessel 1112. The fluid may be returned to the receiver 1110 by a drain tube, for example, by a pump, by fluid pressure, or by some other fluid transfer force. The fluid may exit the cleaning vessel 1112 by one or more process agent return ports 2404 in the receiver. In some cases, this fluid flow is reversible so that, if desired, the fluid can be introduced into the bottom of the cleaning vessel 1112 and flow upward around and through the core assembly 2110 to further clean the core assembly.

[0158] In some embodiments, the cleaning vessel 1112 remains in the spent fuel pool even during core component cleaning operations. In other words, the cleaning vessel 1112 may still be partially or completely submerged in the spent fuel pool when it is at the top of the elevator 1114. By at least partially submerging the cleaning vessel 1112, heat is removed from the cleaning vessel 1112 to the spent fuel pool.

[0159] Once the core assembly 2110 is sufficiently cleaned, the cleaning vessel 1112 is lowered into the spent fuel pool by the elevator 1114. This movement of the elevator 1114 separates the cleaning vessel 1112 from the receiver 1110 and leaves the cleaning vessel 1112 with its top open, allowing water from the spent fuel pool to enter the cleaning vessel 1112 when the open top is submerged in the spent fuel pool.

[0160] According to some embodiments, the removed core assembly is surrounded by the cleaning vessel 1112, receiver 1110, and fuel loading floor valve during cleaning. This reduces the chance of radioactive contamination. This also has the added benefit of simplifying process control and creating a very small pressure boundary around the removed core assembly. A traditional approach to cleaning a core assembly is to place the core assembly in a larger room, pressurize the room, and fill it with cleaning gas before removing the core assembly from the cleaning room and sending it to a spent fuel pool. Creating a pressure and cleaning boundary around the immediate vicinity of the core components makes the cleaning process much more efficient because it can be performed faster, cleaning fluid can be forced through the core assembly in more than one direction, substantially reducing the amount of cleaning fluid, and the cleaning vessel containing the core assembly can be moved from the fuel loading floor valve down an elevator into the spent fuel pool and adjacent to the PIC rack for core assembly storage.

[0161] Furthermore, placing the cleaning vessel 1112 within the PIC allows the cleaning vessel 1112 to remain at least partially submerged in the spent fuel pool. This facilitates passive cooling of the cleaning vessel 1112. This eliminates or at least reduces the required safety-related cooling equipment. This reduces system complexity and cost, and maintains process agent and fuel temperatures within acceptable levels. The spent fuel pool generally has a large thermal mass compared to the cleaning vessel 1112. As a result, passive cooling of the cleaning vessel 1112 prevents large temperature changes within the spent fuel pool. Furthermore, containing the core assembly within the cleaning vessel avoids the typical pH shock to the spent fuel pool.

[0162] In past processes for storing core components in spent fuel pools, the water level in the spent fuel pool is raised or lowered to accommodate the introduction of core components. The described system and method does not require the water level in the spent fuel pool to change with the introduction of removed core components.

[0163] Referring to Figure 26, a process flow is described for a method for cleaning a core assembly removed from a nuclear reactor 2600. In block 2602, a cleaning vessel is coupled to a receiver. As described herein, the receiver may be static or may be coupled to a fuel loading floor valve. The receiver may also have fluid connections for introducing and removing process fluids.

[0164] The removed core component is passed through the fuel loading floor valve, through the receiver, and inserted into the cleaning vessel at block 2604. The removed core component may be transferred from the core to the fuel loading floor valve by any suitable mechanism or method, although in some cases, transfer from the core to the fuel loading floor valve is accomplished by a BLTC.

[0165] Once the core components are placed in the cleaning canister, the fuel loading floor valve is closed in block 2606, thereby forming a sealed chamber within the cleaning canister.

[0166] At block 2608, a cleaning fluid may be introduced into the cleaning vessel, for example, by a process agent inlet disposed in the receiver. The cleaning fluid may be any suitable fluid and, in some cases, may include an inert gas containing water. The cleaning fluid may additionally or alternatively include a liquid (e.g., water) that can react with residual sodium and remove it from the core assembly. The flow of the cleaning fluid may be reversible, allowing the cleaning fluid to pass through the core assembly in more than one direction, as desired.

[0167] In some cases, one or more sensors may be used to measure any off-gassing resulting from the cleaning process. For example, the amount of hydrogen evolved during the cleaning process may be measured and used to indicate when the cleaning process is complete. In some cases, the evolved hydrogen may be continuously measured so that a level of evolved hydrogen approaching a threshold (e.g., 0) indicates that the cleaning process is nearing completion.

[0168] At block 2610, the cleaning canister is moved down the elevator and into the spent fuel pool. As described elsewhere herein, once the cleaning canister is away from the receiver, the cleaning canister may have an open top end, allowing water from the spent fuel pool to enter the cleaning canister. Additionally, the cleaning canister may be partially submerged in the spent fuel pool during the cleaning operation, thereby passively cooling the cleaning canister during the cleaning process.

[0169] In block 2612, the core components are placed in a spent fuel pool for storage. In some cases, the cleaning canister may be received at the bottom of an elevator, such as by a PIC trolley, where it may be transported to a storage location (e.g., an SFP rack in the spent fuel pool). The core assembly may then be removed from the cleaning canister, such as by a crane or pool handling machine, and placed in a PIC rack for storage.

[0170] Those skilled in the art will recognize that any process or method disclosed herein can be modified in many ways. The process parameters and sequences of the processes described and / or illustrated herein are given by way of example only and can be changed as desired. For example, although the processes illustrated and / or described herein may be shown or described in a particular order, these processes do not necessarily have to be performed in the order illustrated or described.

[0171] The various exemplary methods described and / or illustrated herein may omit one or more of the steps described or illustrated herein or may include additional steps in addition to those disclosed. Furthermore, the steps of any method disclosed herein may be combined with any step or steps of any other method disclosed herein.

[0172] Unless otherwise specified, the terms "connected" and "coupled" (and their derivatives) as used in the specification and claims should be interpreted as allowing for both direct and indirect (i.e., via other elements or components) connections. Furthermore, the terms "a" or "an" as used in the specification and claims should be interpreted as meaning "at least one of." Finally, for ease of use, the terms "including" and "having" (and their derivatives) as used in the specification and claims are interchangeable with the word "comprising" and shall have the same meaning.

[0173] The processor may be configured with instructions to perform any one or more steps of any of the methods disclosed herein.

[0174] As used herein, the term "or" is used inclusively to refer to items in alternative or combination.

[0175] As used herein, letters such as numbers refer to like elements.

[0176] The embodiments of the present invention shown and described herein are provided by way of example only. Those skilled in the art will recognize numerous adaptations, modifications, variations, and substitutions without departing from the scope of the present disclosure. Several alternatives and combinations of the embodiments disclosed herein may be utilized without departing from the scope of the disclosure and invention disclosed herein. Accordingly, the scope of the present disclosure is to be defined solely by the appended claims and their equivalents. [Brief explanation of the drawings]

[0177] [Figure 1] 1 is a schematic diagram of a nuclear facility showing a reactor building, a fuel handling facility, and a fuel storage facility, according to some embodiments. [Figure 2] FIG. 1 illustrates a perspective view of a schematic diagram of a nuclear facility, according to some embodiments. [Figure 3] 1 is a schematic diagram of a nuclear facility having multiple reactor buildings, fuel handling and fuel storage facilities, according to some embodiments. [Figure 4] FIG. 1 is a schematic diagram of a nuclear facility showing two reactor buildings and a shared refueling floor, according to some embodiments. [Figure 5] FIG. 1 is a perspective view of a nuclear fuel assembly, according to some embodiments. [Figure 6] 1 is a perspective schematic view of a core assembly inspection stand, a conditioning cell, and a jib hoist according to some embodiments. [Figure 7] 1 is a schematic diagram of an EVHM mounted on a rail, according to some embodiments. [Figure 8A] FIG. 1 is a schematic diagram of a pool immersion cell in plan view, according to some embodiments. [Figure 8B] FIG. 1 is a schematic diagram of a pool immersion cell in elevation view, according to some embodiments. [Figure 9] FIG. 10 is a sample process diagram for storing irradiated core assemblies, according to some embodiments. [Figure 10] FIG. 10 is a sample process diagram for storing irradiated core assemblies, according to some embodiments. [Figure 11] FIG. 1 is a perspective view of a pool immersed (PIC) cell showing an exemplary location of a sodium removal machine, according to some embodiments. [Figure 12] FIG. 1 is a perspective view of a PIC machine, according to some embodiments. [Figure 13] 1 illustrates a bottom loading transfer cask (BLTC) coupled with an embodiment of a PIC machine, according to some embodiments. [Figure 14] 10A-10C are cross-sectional views illustrating the mating structure between the BLTC and the PIC machine, according to some embodiments. [Figure 15] FIG. 10 is a partial cutaway view of a PIC machine showing a cleaning receptacle, according to some embodiments. [Figure 16] FIG. 10 illustrates the motion of a PIC machine, according to some embodiments. [Figure 17] FIG. 10 illustrates the PIC machine elevator at its downward travel limit, according to some embodiments. [Figure 18] 10 illustrates a PIC machine disengaged from a cleaning receptacle, according to some embodiments. [Figure 19] 1 illustrates a PIC machine in a full overtravel state with the cleaning receptacle disengaged, according to some embodiments. [Figure 20]1 illustrates a PIC trolley with a cleaning container traveling to a spent fuel pool (SPF) according to some embodiments. [Figure 21] 1 illustrates a PIC machine and PIC top components, according to some embodiments. [Figure 22] 1 illustrates the upper area of ​​a cleaning vessel with a core assembly according to some embodiments. [Figure 23] 1 illustrates a lower area of ​​a cleaning vessel with a core assembly according to some embodiments. [Figure 24] 1 illustrates a cross-sectional view of a receiver and cleaning receptacle with seals and tubing connections according to some embodiments. [Figure 25] 1 illustrates a cross-sectional view of a PIC receiver and cleaning receptacle, according to some embodiments. [Figure 26] 1 illustrates a process flow for cleaning an extracted core assembly.

Claims

1. 1. A method for storing a removed core assembly, comprising: coupling a cleaning container to a fuel loading floor valve; inserting the removed core assembly into the cleaning vessel through the fuel loading floor valve; introducing a cleaning fluid into the cleaning vessel; transporting the cleaning vessel and the core assembly down an elevator into a spent fuel pool; placing the core assembly in the spent fuel pool for storage; A method comprising:

2. 10. The method of claim 1, wherein said step of introducing a cleaning fluid is accomplished by gradually increasing the water content in an inert gas.

3. 10. The method of claim 1, further comprising filling the cleaning vessel with water and reacting residual sodium with the water.

4. coupling the cleaning container to the fuel loading floor valve creates a pressure seal; The method of claim 1 , wherein the step of introducing the cleaning fluid is performed under pressure.

5. 10. The method of claim 1, further comprising the step of at least partially positioning the cleaning receptacle within the spent fuel pool during the step of introducing the cleaning fluid into the cleaning receptacle to provide passive cooling of the cleaning receptacle by the spent fuel pool.

6. loading the cleaning vessel with the core assembly into a trolley; moving the trolley from a first location directly below the elevator to a second location within the spent fuel pool; The method of claim 1 further comprising:

7. 10. The method of claim 1, further comprising the step of flushing the core assembly with water in a first flow direction after the step of introducing the cleaning fluid.

8. further comprising flushing the core assembly with water in a second flow direction; The method of claim 7 , wherein the second flow direction is opposite to the first flow direction.

9. measuring the hydrogen concentration; determining that cleaning is complete based on the measured hydrogen concentration being less than a threshold value; The method of claim 1 further comprising:

10. removing the core assembly from the cleaning bin for storage; inserting a second core assembly into the cleaning vessel; The method of claim 1 further comprising:

11. 1. A sodium removal machine for cleaning an extracted core assembly, comprising: a receiver coupled to the fuel loading floor valve, the receiver having one or more process fluid connections; a cleaning receptacle having an open top end and a closed bottom end; an elevator configured to transport the cleaning receptacle from an upper position where the cleaning receptacle is coupled to the receiver and a lower position where the cleaning receptacle is not coupled to the receiver; sodium removal machine, including

12. The sodium removal machine of claim 11 , wherein the receiver is static and, when coupled to the cleaning receptacle, forms a closed boundary for the removed core assembly.

13. the cleaning bin includes a receptacle configured to receive a portion of the removed core assembly; The sodium removal machine of claim 11 , wherein the receptacle is configured to form a seal with the portion of the removed core assembly.

14. the one or more process fluid couplings include a process fluid inlet located above the cleaning receptacle; The sodium removal machine of claim 11 , wherein the process fluid passes through the process fluid inlet and enters the cleaning vessel and the core assembly.

15. the receiver has a first cross-sectional dimension; the core assembly has a second cross-sectional dimension; 12. The sodium removal machine of claim 11, wherein the first cross-sectional dimension is less than twice the second cross-sectional dimension.

16. the receiver has a first length; the core assembly has a second length; 12. The sodium removal machine of claim 11, wherein the first length is less than twice the second length.

17. the elevator selectively couples with the cleaning bin; 12. The sodium removal machine of claim 11, wherein the elevator automatically disconnects from the cleaning bin when the elevator is in the lower position.

18. The sodium removal machine of claim 11 , wherein the cleaning vessel is at least partially submerged in a spent fuel pool when the elevator is in the upper position.

19. further comprising a hydrogen sensor; The sodium removal machine of claim 11 , wherein the hydrogen sensor is configured to measure a hydrogen concentration at a process agent outlet of the cleaning vessel.

20. a damaged fuel canister configured to replace the cleaning container and engage the elevator; The sodium removal machine of claim 11 , wherein the breached fuel canister is further configured to receive a breached fuel assembly for delivery to the lower location.

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