HK1262259A1 - Inter-module fuel shuffling - Google Patents

Description

Inter-module fuel switching

Benefits of government

The invention was made with government support under contract number DE-NE0000633 awarded by the department of energy. The government has certain rights in this invention.

Statement of related matters

This application claims priority from U.S. application No.15/445,186 filed on 28.2.2017, which claims priority from U.S. provisional application No.62/314,523 filed on 29.3.2016 entitled "Inter-Module Shuffling for Fuel cycle optimization," the contents of which are incorporated herein by reference in their entirety.

Background

While the fuel costs of certain types of nuclear power plants may be lower and more stable than fossil fuel power plants of comparable size, the fuel costs of nuclear power plants may still reach millions of dollars per year. To optimize the operation of the entire plant, only a small fraction of the actual fissile isotopes in the nuclear fuel are typically consumed before the fuel is discharged from the reactor to the spent fuel pool.

In known Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs), the reactor core may contain a large number of fuel rods, which may be arranged as a plurality of fuel assemblies. Some improvements in fuel burn-up may be achieved by rearranging burning fuel assemblies within a large reactor core, which may contain over 200 fuel assemblies; however, core physical factors significantly limit the potential gains in fuel consumption and the corresponding fuel cost reductions.

During refueling operations in which some or all of the fuel rods in the reactor core may be replaced, the reactor vessel must be at least partially disassembled in order to gain access to the reactor core. Therefore, the reactor must be shut down during refueling operations, when a typical power plant is no longer capable of generating electricity.

The present application addresses these and other issues.

Disclosure of Invention

Disclosed herein are exemplary methods of loading fuel in a plurality of reactor cores associated with a plurality of fuel cycles. An example method may include, in a first fuel cycle, loading a first reactor core with a first fuel assembly selected from a first batch of fuel, loading the first reactor core with a first portion of spent fuel assemblies from a second batch of fuel, loading a second reactor core with a second fuel assembly from the first batch of fuel, and loading the second reactor core with a second portion of spent fuel assemblies from the second batch of fuel. In a second fuel cycle, which may be performed after completion of the first fuel cycle, the method may include loading a second reactor core with fresh fuel assemblies and loading the second reactor core with first fuel assemblies from the first batch of fuel.

An example fuel loading system is disclosed herein. An exemplary fuel loading system may include: a fuel storage facility configured to store a number of fuel assemblies associated with a plurality of on-site reactor cores; and a transportation facility configured to transport the spent fuel assembly to a fuel storage facility. The first reactor core may include a first fuel loading configuration including a first fuel assembly associated with a first batch of fuel and a first portion of spent fuel assemblies associated with a second batch of fuel.

The second reactor core may include a second fuel loading configuration including a second fuel assembly associated with the first batch of fuel, a second portion of spent fuel assemblies associated with the second batch of fuel, and a third cycle fuel assembly including a portion of spent nuclear fuel that has previously completed two fuel cycles. After the previous fuel cycle, a second portion of the spent fuel assemblies may be removed from the first reactor core and transported to a fuel storage facility.

Additionally, the third reactor core may include a third fuel loading configuration including a third fuel assembly associated with the first batch of fuel and a third portion of spent fuel assemblies replacing a third recycle fuel assembly in the third reactor core. After the previous fuel cycle, the third cycle fuel assembly may be removed from the third reactor core and transported to a fuel storage facility.

Example storage devices are disclosed herein. An exemplary storage device may have instructions stored thereon that, in response to execution by a processing device, cause the processing device to perform operations. The operations may include: for a first fuel cycle, a first fuel configuration associated with a first reactor core is determined. The first fuel configuration may include a first fuel assembly selected from a first batch of fuel and a first portion of spent fuel assemblies selected from a second batch of fuel. The operations may further include: for the first fuel cycle, a second fuel configuration associated with a second reactor core is determined.

The second fuel configuration may include a second fuel assembly selected from the first batch of fuel and a second portion of the spent fuel assembly selected from the second batch of fuel. Additionally, the operations may include: for a second fuel cycle conducted after completion of the first fuel cycle, a second fuel configuration associated with the second reactor core is updated to include fresh fuel assemblies and first fuel assemblies selected from the first batch of fuel.

Drawings

FIG. 1 illustrates an example nuclear reactor module.

FIG. 2 illustrates an example nuclear reactor module including a partially disassembled reactor pressure vessel.

Fig. 3 illustrates an exemplary reactor core.

FIG. 4 shows an enlarged view of an exemplary fuel assembly.

FIG. 5A illustrates a plan view of an exemplary fuel assembly array associated with a first fuel cycle.

FIG. 5B illustrates a plan view of an exemplary fuel assembly array associated with a second fuel cycle.

FIG. 5C illustrates a plan view of an exemplary fuel assembly array associated with a third fuel cycle.

Fig. 6 shows a nuclear power plant comprising a plurality of reactor modules.

FIG. 7A illustrates an exemplary fuel shuffling configuration associated with a number of fuel cycles.

FIG. 7B illustrates another example fuel shuffling configuration associated with subsequent fuel cycles.

FIG. 7C illustrates yet another example fuel shuffling configuration associated with another fuel cycle.

Fig. 8A shows an exemplary fuel-flipping configuration, where fuel can be flipped in both the forward and reverse directions.

FIG. 8B illustrates another example multi-way fuel shuffling configuration associated with subsequent fuel cycles.

FIG. 8C illustrates yet another example multi-way fuel shuffling configuration associated with subsequent fuel cycles.

FIG. 9 illustrates an exemplary system associated with loading fuel in a plurality of reactor cores.

FIG. 10 illustrates an exemplary fuel shuffling process for multiple reactor cores associated with multiple fuel cycles.

Detailed Description

Various examples disclosed and/or referenced herein may operate In accordance with or In conjunction with one or more features of U.S. patent application serial No.15/004,128 entitled "In-core instrumentation" filed on 22/1/2016, the entire contents of which are incorporated herein by reference.

Fig. 1 illustrates an example nuclear reactor module 100 having a dry and/or evacuated containment region 14. The nuclear reactor module 100 may include a reactor core 6 surrounded by a reactor pressure vessel 52. The primary coolant 10 in the reactor pressure vessel 52 surrounds the reactor core 6.

The reactor pressure vessel 52 may be surrounded by a containment vessel 54. In some examples, containment vessel 54 may be located in reactor pool 150. The reactor pool 150 may include borated water stored below ground level. Containment vessel 54 may be at least partially submerged in reactor pool 150. In some examples, at least a portion of the upper head of the containment vessel 54 may be located above the surface 155 of the reactor pool 150 in order to maintain any electrical connections and/or through-drying through the upper head. Additionally, containment vessel 54 may be configured to inhibit any primary coolant 10 associated with reactor pressure vessel 52 from being released to escape containment vessel 54 into reactor pool 150 and/or the ambient environment.

The receiving container 54 may be substantially cylindrical in shape. In some examples, containment vessel 54 may have one or more oval, dome, or spherical ends, thereby forming a capsule-shaped vessel. Containment vessel 54 may be welded or otherwise sealed from the environment such that liquids and/or gases are not allowed to escape from vessel 54 or enter vessel 54 during normal operation of reactor module 100. In various examples, the reactor pressure vessel 52 and/or containment vessel 54 may be bottom supported, top supported, supported about its center, or any combination thereof.

In some examples and/or modes of operation, the inner surfaces of the reactor pressure vessel 52 may be exposed to a humid environment including the primary coolant 10 and/or steam, and the outer surfaces of the reactor pressure vessel 52 may be exposed to a substantially dry environment. The reactor pressure vessel 52 may include and/or be made of stainless steel, carbon steel, other types of materials, or composite materials, or any combination thereof.

A containment region formed within containment vessel 54 may substantially surround reactor pressure vessel 52. In some examples and/or modes of operation, containment region 14 may include a dry, empty, evacuated, and/or gaseous environment. The containment region 14 may include a quantity of air, a nobel gas such as argon, other types of gases, or any combination thereof. Additionally, the surfaces of one or both of the reactor pressure vessel 52 and containment vessel 54 that define the containment region 14 may be exposed to water during certain modes of operation within the reactor pool 150 (e.g., refueling, shut-down, or transport).

The containment region 14 may be maintained at or below atmospheric pressure, including a partial vacuum of about 300mmHG absolute (5.8psia) or less. In some examples, the containment region 14 may be maintained at a pressure of about 50mmHG absolute (1 psia). In other examples, the containment region 14 may be maintained at a substantially complete vacuum. Any gas or gases in the containment vessel 54 may be evacuated and/or removed prior to operation of the reactor module 100. During normal operation of the reactor module 100, the containment region 14 may remain dry and/or be drained of any water or liquid. Similarly, containment region 14 may remain at least partially evacuated of any air or gas.

The heat exchanger may be configured to circulate feedwater and/or steam in a secondary cooling system for power generation. In some examples, the feedwater passes through a heat exchanger and may become superheated steam. The feedwater and/or steam in the secondary cooling system remains isolated from the primary coolant 10 in the reactor pressure vessel 52, thereby not allowing them to mix with each other or come into direct (e.g., fluid) contact with each other.

The heat exchanger and/or associated piping of the second cooling system may be configured to penetrate the reactor pressure vessel 52 at one or more plenums 30. Additionally, secondary piping may be disposed to an upper region of the vessel above the level of the reactor pool 150, with the piping passing through the containment vessel 54. By exiting the vessel above the reactor pool 150, the high temperature steam and feedwater lines do not dissipate heat to the reactor pool water 150.

During a normal non-scram, the one or more steam generators may be configured to release steam and cool the reactor module 100 from a normal operating temperature to about 250 ° F (121 ℃). However, since the process of releasing steam may become somewhat ineffective at 250 ° F, the closer the temperature of the reactor module reaches the boiling temperature of the secondary coolant, the more nearly the temperature of the reactor module may become substantially static or fixed.

The cooling process may be enhanced by at least partially flooding the containment region 14 of the example reactor module 100. In some examples, the containment region 14 may be flooded with borated water from the reactor pool 150 until the water level reaches or is above the height of a pressurizer baffle positioned in the reactor pressure vessel 52. During the cooling process, water entering the containment region 14 remains outside of the reactor pressure vessel 52, and similarly, all of the primary coolant 10 remains within the reactor pressure vessel 52.

The upper head of the reactor pressure vessel 52 may be maintained above water level to avoid being submerged or otherwise exposed to water through any connections of the upper head. In some examples, the predetermined water level within the containment region 14 may be associated with the overflow containment region 14 such that a majority of the reactor pressure vessel 52 is surrounded by water. In other examples, the entire reactor pressure vessel 52 may be enclosed or submerged in water overflowing the containment region 14.

The containment region 14 may be at least partially filled with water to initiate a passive cooling process to a cold shut-down condition, for example, a shut-down condition associated with a primary coolant temperature below 200 ° F (93 ℃). Once the containment region 14 is flooded above a predetermined level, no further action may be required, and passive cooling to operating temperatures below 200 ° F may occur primarily as a function of the following factors: natural circulation of the primary coolant 10 within the reactor pressure vessel 52, the decay heat of the shutdown reactor, heat transfer from the primary coolant 10 to the water in the containment region 14, and the temperature of the reactor pool 150.

Fig. 2 illustrates an example nuclear reactor module 200 including a reactor pressure vessel 220 housed within a partially disassembled containment vessel 240. The incore instrument 230 may be removed from the reactor core 260 contained within the reactor pressure vessel 220. In some examples, the incore instruments 230 may include twelve or more incore instrument assemblies. Each in-core assembly may include monitors, sensors, measurement devices, detectors, other types of instrumentation, or any combination thereof.

The lower vessel header 225 is shown having been removed from the reactor pressure vessel 220, such as during refueling, maintenance, inspection, or other non-operational procedures of the reactor module 200. During disassembly of the containment vessel 240, the lower vessel head 225 may remain fully submerged below the surface 155 of the reactor pool, such as the reactor pool 150 (fig. 1). While the reactor pressure vessel 220 may remain intact and/or sealed during disassembly of the containment vessel 240, at least a lower portion of the reactor pressure vessel 220 may also be surrounded by a reactor pool.

The reactor pressure vessel 220 may be removably attached to a lower vessel header 225 by an upper vessel flange 222 and a lower vessel flange 224. For example, a plurality of bolts may pass through and/or connect the upper vessel flange 222 to the lower vessel flange 224. The bolts may be loosened and/or removed prior to removing the lower vessel head 225 from the reactor pressure vessel 220. In some examples, the containment vessel 240 may be similarly disassembled prior to removal of the lower vessel header 225.

As a result of removing the lower vessel header 225 from the reactor pressure vessel 220, the in-core instrumentation 230 may be efficiently withdrawn from the reactor core 260 when the lower vessel header 225 is detached. During non-operational processes (e.g., refueling), a visual inspection of the exterior of the reactor pressure vessel 220 and containment vessel 240 may be performed. After removal of the lower vessel header 225, the flange and inner surface of the vessel may be remotely inspected while the vessel and/or lower header are supported in one or more racks. In some examples, the remote inspection may include ultrasonic testing of critical welds and a full visual inspection of the inner surface. Additionally, some or all of the inspection may occur below the surface 155 of the reactor pool.

Retrieval of the incore instrument 230 from the reactor core 260 and guide tube may be accomplished without breaking the watertight seal formed between the containment vessel 240 and the surrounding water pool. For example, during disassembly of the reactor pressure vessel 220 and containment vessel 240, the upper head of the containment vessel 240, which is at least partially above the surface 155 of the reactor pool, may remain completely sealed to the surrounding environment. In addition, the lower vessel header 225 may be moved to the refueling compartment or held behind without movement so that multiple operations may be performed on separate components of the reactor module 200.

During disassembly and transportation of the reactor module 200 and/or containment vessel 240, the lower end of the incore instrument 230 may remain submerged in and surrounded by the reactor pool water at all times. The reactor pool water may be used to reduce the temperature of the incore instrumentation 230 and provide shielding for any radiation that may be emitted from the lower end.

Fig. 3 illustrates an exemplary reactor core 300, which may be configured similarly to the reactor core 260 of fig. 2. The reactor core 300 may include an array of fuel assemblies 325, which may be arranged in a substantially symmetrical pattern. The fuel assembly array 325 may include a plurality of fuel assemblies (e.g., fuel assemblies 400 partially removed from the reactor core 300) and one or more neutron sources. The number of fuel assemblies included in a reactor core may vary from one reactor to another depending, at least in part, on the total amount of power that the reactor may be configured to produce. In the exemplary reactor core 300, a total of thirty-seven fuel assemblies are shown, although more or fewer fuel assemblies per reactor core are contemplated herein.

Some or all of the fuel assemblies may be removed, added, and/or replaced from the reactor core 300 during one or more processes (e.g., an inspection process or a refueling process). Additionally, in some examples, various fuel assemblies may be interchangeably positioned or placed within the reactor core 300 such that the fuel assembly 400 may be moved from one location in the array 325 to another location in the array during one or more fuel cycles.

The width 350 of the reactor core 300 may vary depending on the number and/or size of fuel assemblies. By way of illustrative example only, the width 350 may be approximately 1.5 meters, and other widths associated with the reactor core 300 are contemplated herein.

FIG. 4 illustrates an enlarged view of an exemplary fuel assembly 400 isolated from a reactor core. The fuel assembly 400 may include a plurality of fuel rods 425. In some examples, fuel assembly 400 may include more than one hundred fuel rods. The fuel rods 425 may be supported within the fuel assembly 400 by the upper and lower mounting structures 410 and 420. Additionally, the fuel assembly 400 may include a plurality of guide tubes (visible from above the upper mounting structure 410) into which one or more control rods may be inserted during reactor operation.

The fuel rods 425 may include radioactive materials, such as uranium oxide (UO2) fuel, mixed uranium-plutonium oxide (MOX) fuel, other types of nuclear fuels, or any combination thereof. As the effective concentration of uranium or other radioactive material is consumed or depleted with use and/or time, the overall level of reactivity of the fuel assembly 400 may decrease. In some examples, the fuel assemblies 400 may be shipped and/or stored as a unitary structure before, during, or after use in a reactor, and they do not require removal of the control rods 425 once they are installed. In other examples, once the useful life of fuel assembly 400 is complete, individual control rods may be removed for reprocessing or disposal.

The height 450 of the fuel assembly 400 may vary depending on the size of the fuel rods 425. By way of illustrative example only, height 450 may be approximately 2.5 meters, and other heights associated with fuel assembly 400 are contemplated herein.

FIG. 5A illustrates a plan view of an exemplary fuel assembly array 500 associated with a first fuel cycle. Fuel assembly array 500 may be logically divided into a plurality of sections, and in some examples, there may be three sections. The number of segments may correspond to the number of expected fuel cycles, and in some examples, the segments may be oriented in an approximately concentric arrangement in fuel array 500.

The first section 510 of the fuel array 500 may include a number of fuel assemblies denoted "a 0," and in some examples, the a0 fuel assemblies may represent new or fresh fuel that has not been consumed in the reactor. The first section 510 may be located generally in an outer concentric region of the fuel array 500. For clarity, the location of the exemplary first segment 510 is emphasized in fig. 5A.

The second section 520 of the fuel array 500 may include a number of fuel assemblies denoted as "B," and in some examples, the B fuel assemblies may represent fuel that has been partially consumed in the reactor. The second section 520 may be located substantially inside the concentric region associated with the first section 510. For clarity, the location of the exemplary second segment 520 is emphasized in fig. 5B.

The third section 530 of the fuel array 500 may include a number of fuel assemblies denoted as "C," and in some examples, C fuel assemblies may represent fuel that has been partially consumed in the reactor. The third section 530 may be located substantially inside the concentric region associated with the second section 520, or in some examples, primarily in a central region of the array 500. For clarity, the location of the exemplary third segment 530 is emphasized in fig. 5C.

The radioactivity or reactivity associated with each segment may vary. For example, the B fuel assemblies associated with the second segment 520 may be more reactive than the C fuel assemblies associated with the third segment 530, and the B fuel assemblies may be less reactive than the a0 fuel assemblies associated with the second segment 520. Additional sections and/or numbers of concentric fuel regions may be provided in other exemplary fuel assembly arrays depending on the size of the reactor core and/or the number of fuel cycles associated with the fuel.

In some examples, the number of a0 fuel assemblies in the first segment 510 may be equal to the number of B fuel assemblies in the second segment 520, and similarly, the number of B fuel assemblies in the second segment 520 may be equal to the number of C fuel assemblies in the third segment 530.

The neutron source may be located at the center "S" of the fuel array 500. In other examples, the fuel assemblies may be located at the center S of the array 500, which may or may not be inverted with other sections. In other examples, the center S may remain open to provide a passage or channel for coolant and/or to accommodate a medium that promotes fast neutron thermalization, thereby increasing neutron absorption in the surrounding fuel assembly.

Fig. 5B shows a plan view of an exemplary fuel assembly array 500 associated with a second fuel cycle, where some or all of the fuel assemblies may be flipped. The a0 fuel assembly located at the first segment 510 in fig. 5A may be moved to the second segment 520, and similarly, the B fuel assembly located at the second segment 520 in fig. 5A may be moved to the third segment 530. In some examples, the first section 510 of the fuel array 500 may include a number of fuel assemblies denoted "a 1" and these fuel assemblies represent a new or fresh batch of fuel that has not been consumed in the reactor core prior to the second fuel cycle.

FIG. 5C shows a plan view of an exemplary fuel assembly array 500 associated with a third fuel cycle, where some or all of the fuel assemblies may be flipped again. The a1 fuel assembly located at the first segment 510 in fig. 5B may be moved to the second segment 520, and similarly, the a0 fuel assembly located at the second segment 520 in fig. 5B may be moved to the third segment 530. In some examples, the first section 510 of the fuel array 500 may include a number of fuel assemblies denoted "a 2" and these fuel assemblies represent a new or fresh batch of fuel that has not been consumed in the reactor prior to the third fuel cycle.

The fuel assemblies associated with each segment may be associated with different amounts of remaining useful life or number of fuel cycles. For example, the a0 fuel assembly located in the third segment 530 may have previously undergone two fuel cycles prior to the third fuel cycle, as can be readily understood with reference to the highlighted portions shown in the progression of fig. 5A-5C. On the other hand, the a1 fuel assembly located in the second segment 520 may have previously undergone only one fuel cycle before the third fuel cycle.

For a fuel array 500 associated with a three cycle refueling process or fuel switch, the a0 fuel assembly may have one remaining fuel cycle, e.g., the third fuel cycle, before its useful life is complete, while a new a2 fuel assembly may still have three remaining fuel cycles of useful life, including the third fuel cycle. In some examples, each fuel assembly may be swapped between different sections of the fuel array during its useful life.

While the direction of fuel shuffling shown in fig. 5A-5C is shown as occurring from the outer fuel assembly location or first section 510 of the fuel array 500 toward the third section 530 or center S, in other examples, the direction of fuel shuffling may be directed in an opposite manner from the third section 530 or center S toward the outer fuel assembly location of the fuel array 500. In other examples, fuel shuffling may be implemented in other geometric patterns or combinations of orientations to provide alternative reactivity curves.

Fig. 6 shows a nuclear power building 600 comprising a plurality of reactor modules, for example a reactor module 610 and a further reactor module 620. The nuclear power building 600 is shown as including only twelve reactor modules, and fewer or more reactor modules per nuclear power building are contemplated herein.

The nuclear power building 600 may include an overhead crane 655 configured to move or transport a plurality of reactor modules. In the example shown, the reactor module 610 has been removed from the reactor bay 630 and is in the process of being transported through the common reactor building channel 650. The channel 650 may be fluidly connected to each reactor compartment, such as reactor compartment 630, to allow the reactor module 610 to be transported by crane 655 while being at least partially submerged.

The channel 650 may fluidly connect the reactor compartment 630 to a spent fuel pool 680 and/or a dry dock 690. Additionally, channels 650 may fluidly connect reactor compartment 630 to a refueling compartment 665 that includes containment vessel mount 660 and reactor pressure vessel mount 670.

The containment vessel bracket 660 may be configured to assemble and/or disassemble a containment vessel, such as the containment vessel 240 (fig. 2), after the reactor module is shut down. During disassembly of the reactor module, the lower containment head of the containment vessel may be placed in the containment vessel bracket 660. For example, the crane may be configured to transport the entire reactor module from the reactor bay and then lower the reactor module into the containment vessel cradle 660.

After placement in the containment vessel bracket 660, the containment flange associated with the lower containment head may be loosened by a containment tool, such as by loosening and/or removing a number of bolts. With the lower containment head separated from the containment vessel, the reactor module may be lifted from the containment vessel support 660 by a crane and placed in the reactor pressure vessel support 670. With the lower containment head left behind in the containment vessel bracket 660, the lower vessel head associated with the reactor pressure vessel may be placed in the reactor pressure vessel bracket 670.

After placement in the reactor vessel mount 670, the reactor vessel flange associated with the lower vessel head may be loosened by a reactor vessel tool, such as by loosening and/or removing a number of bolts. One or both of the reactor pressure vessel tool and the containment tool may be remotely operable. With the lower vessel header separated from the reactor pressure vessel, the reactor module may be lifted from the reactor pressure vessel mount 670 and moved to a maintenance facility by a crane. Additionally, the lower vessel header may be moved separately from the reactor module, or the lower vessel header may be refueled and/or perform maintenance work while remaining in the reactor pressure vessel holder 670.

By including multiple reactor modules, the reactor module 610 may be taken off-line for refueling and/or maintenance while the remaining reactor modules continue to operate and generate power. In a nuclear power plant including twelve reactor modules, each having a design fuel life of two years, different reactor modules may be refueled every two months as part of a continuous refueling cycle. For reactor modules with longer design fuel life, the reactor module may be refueled less frequently.

Fuel transport apparatus 640 may be configured to transport one or more fuel assemblies between refueling compartment 665 and fuel storage facility 680. In some examples, the fuel transport equipment 640 may include an automated fuel loading system for removing, replacing, or adding fuel to the reactor core.

In some examples, the fuel transport facility 640 may include a Lower Vessel Inspection Tree (LVIT) that may be configured to access the nuclear power building 600 through an opening or door for visual and/or ultrasonic inspection of the reactor modules. In some examples, the fuel transport equipment 640 and/or the LVIT may be moved within the nuclear power building 600 by a crane 655.

Each reactor module included in the nuclear power building 600 may include a relatively small reactor core, which in some examples may include 37 fuel assemblies. Thus, a twelve-module power plant having a similarly configured reactor core may be understood to contain a total of 444 fuel assemblies in twelve operating cores. The exhausted and/or partially spent fuel assemblies and new fuel assemblies may be stored in a common spent fuel pool 680. In some examples, a multi-module power plant configuration may thus allow for the possibility of cross-loading fuel assemblies that are discharged from one module into another. By judicious module-to-module switching of the assemblies, fuel consumption can be maximized while maintaining reactivity limits for each operating core.

FIG. 7A illustrates an example fuel configuration 700 or fuel shuffling process that may be associated with a certain number of fuel cycles. For a multi-module power plant including three or more reactor modules and/or three or more reactor cores, an inter-module refueling process may be associated with the first reactor core 710, the second reactor core 720, and the third reactor core 730. In some examples, fuel shuffling configuration 700 may be associated with three or more fuel cycles, where three batches of fuel may be shuffled or otherwise moved between reactor cores.

The first batches of fuel 712, 722, 732 may be associated with a first reactor core 710, a second reactor core 720, and a third reactor core 730, respectively. The first fuel may comprise fresh fuel or new fuel. In some examples, the first batch of fuel may be located at an external reactor core location, such as the first section 510 of fig. 5A.

Similarly, second batches of fuel 714, 724, 734 may be associated with first reactor core 710, second reactor core 720, and third reactor core 730, respectively. The second batch of fuel may comprise fuel that has been used or partially consumed during a previous fuel cycle. In some examples, the second batch of fuel may be located at an intermediate reactor core location, such as the second section 520 of fig. 5B.

Further, third batches of fuel 716, 726, 736 may be associated with first reactor core 710, second reactor core 720, and third reactor core 730, respectively. The third batch of fuel may include fuel that has been used or partially consumed during two previous fuel cycles. In some examples, the third batch of fuel may be located at a central reactor core location, such as the third section 530 of fig. 5C.

During the first fuel cycle, the three reactor cores 710, 720, 730 may operate with the fuel configuration shown in fig. 7A. For example, the first reactor core 710 may be on-line or on-line with the fuels 712, 714, 716. Similarly, second reactor core 720 may be on-line with fuels 722, 724, 726, and third reactor core 730 may be on-line with fuels 732, 734, 736.

At the end of the first fuel cycle, some or all of the fuel may be switched between reactor cores. Fuel 712, 714 may move from first reactor core 710 to second reactor core 720, and fuel 722, 724 may move from second reactor core 720 to third reactor core 730. In some examples, it may be generally understood that fuel moves in a "forward" direction, from first reactor core 710 to second reactor core 720, and from second reactor core 720 to third reactor core 730. Additionally, it is generally understood that fuel moves from the outer section of the reactor core to the central section of the reactor core while fuel is being shuffled between the reactor cores, as further understood with reference to fig. 5A-5C.

In a multi-module power plant consisting of three reactor cores, the fuel 732, 734 may be moved from the third reactor core 730 to the first reactor core 710 in a manner similar to that described directly above. In some examples, the fuel may be switched in a closed loop or circular pattern, with the fuel moving between the three reactor cores at the end of each subsequent fuel cycle.

In a multi-modular plant including more than three reactor cores, the fuels 732, 734 may be moved from the third reactor core 730 to a fourth reactor core (not shown). The fourth reactor core may be associated with a second set of three reactor cores, which may be similarly configured to reactor cores 710, 720, 730. In some examples, a power plant may be configured with a number of reactor cores equal to a multiple of the number of fuel cycles.

In an example of a three fuel cycle switch process, a power plant may include three reactor cores, six reactor cores, nine reactor cores, twelve reactor cores, etc. Each set of three reactor cores may be constructed similarly to reactor cores 710, 720, 730, and in some examples, the fuel shuffling may be done between each set of reactor cores to create a larger closed loop or circular pattern of fuel shuffling when subsequent reactor cores are online.

In an exemplary four-cycle fuel shuffling process, the power plant may be configured with multiple sets of four reactor cores, such that the power plant may include four reactor cores, eight reactor cores, twelve reactor cores, and so on. Further, the number of fuel batches associated with each reactor core may be equal to the number of fuel cycles. In an exemplary three-cycle fuel shuffling process, each reactor core may be associated with three batches of fuel arranged at three discrete locations within the reactor core. While in the exemplary four-cycle fuel shuffling process, each reactor core may be associated with four batches of fuel arranged in four discrete locations within the reactor core.

At the end of the fuel cycle associated with the fuel configuration shown in fig. 7A, the fuels 716, 726, 736 may be understood to have been used for three fuel cycles, and in some examples, may be further understood to have their useful lives at the end. Thus, the fuel 716, 726, 736 may be removed from the reactor core 710, 720, 730 and processed, reprocessed or stored in the fuel storage facility 790, or otherwise disposed of. In some examples, the fuel storage facility 790 may be understood to include a common spent fuel pool. Similarly, at the end of the fuel cycle, new or fresh fuel from the fuel source 780 may be added to the reactor core 710, 720, 730 to replace the fuel that has been removed.

The fresh fuel 780 may be placed in the reactor cores 710, 720, 730 in a similar manner as described with respect to the fuel array 500 shown in fig. 5A-C. For example, new fuel may be placed at the outer periphery of the reactor core, while the fuel 716, 726, 736 may be removed from the central or interior section of the respective reactor core. Fuel may be switched between the reactor cores 710, 720, 730 to optimally perturb or reconfigure the power distribution. The full cycle mode may be repeated for a third core reload of every third fuel cycle.

Fig. 7B illustrates another example fuel shuffling configuration associated with a subsequent or second fuel cycle, where new fuel 742, 752, 762 has been added to reactor cores 710, 720, and 730, respectively, and the partially used fuel has been shuffled as previously described with reference to one or more examples described with respect to fig. 7A.

In addition to the new fuel 742, the first reactor core 710 is shown to include fuel 782 that was previously used for one fuel cycle and fuel 784 that has been used for two previous fuel cycles. In addition to the new fuel 752, the second reactor core 720 is shown to include fuel 712 that was previously used for one fuel cycle in the first reactor core 710 and fuel 714 that has been used for two previous fuel cycles. Similarly, a third reactor core 730 is shown to include a portion of the spent fuel 722 and fuel 724 received from the second reactor core 720.

At the end of the second fuel cycle, fuel 742 and fuel 782 may be moved from first reactor core 710 to second reactor core 720, and fuel 784 that has been used for three fuel cycles may be removed from first reactor core 710 and stored in fuel storage facility 790 or otherwise disposed of. Similarly, fuel 752 and fuel 712 may move from second reactor core 720 to third reactor core 730. The fuel 714, 724 already used for the three fuel cycles may be stored in the fuel storage facility 790 or otherwise disposed of. In a third fuel cycle, fresh fuel 780 may be added to some or all of the reactor cores 710, 720, 730 in a similar manner as previously described.

FIG. 7C illustrates yet another example fuel shuffling configuration associated with subsequent fuel cycles. Although the fuel configuration shown in fig. 7B may be accomplished by flipping the fuel in a forward direction to the next sequential reactor core, in other examples, one or more batches of fuel may skip the next reactor core. For example, referring to the fuel configuration 700 shown in fig. 7A, fuel 712 may be moved from a first reactor 710 to a second reactor 720, while fuel 714 may be moved from the first reactor 710 to a third reactor 730. Similarly, fuel 722 may move from the second reactor 720 to the third reactor 730.

For example, in a power plant consisting of three reactor cores or a single set of reactor cores, the fuel 712 may then be moved from the second reactor 720 to the first reactor 710, as shown in phantom. Similarly, the fuel 722 may alternatively move from the third reactor 730 to the second reactor 720. In some examples, the transport of fuel from second reactor 720 back to first reactor 710 and/or from third reactor core 730 back to second reactor core 720 may be understood to be performed in a "reverse" direction.

FIG. 8A illustrates another example fuel configuration 800 or fuel shuffling process in which fuel can be shuffled in the "forward" and "reverse" directions. In the fuel configuration 800, the three-cycle fuel shuffling process may be augmented or supplemented with a fourth or, more generally, n +1 fuel batches, where "n" represents the number of standard fuel cycles associated with the useful life of the fuel.

For a multi-module power plant including four or more reactor modules and/or four or more reactor cores, an inter-module refueling process may be associated with the first reactor core 810, the second reactor core 820, the third reactor core 830, and the fourth reactor core 840. More generally, fig. 8A may be understood to show a set of reactor cores, where n +1 reactor cores are used for n fuel cycles. In an example where the fuel may be associated with a useful life of three fuel cycles, the fourth reactor core 840 may include an n +1 reactor core. The additional groups of n +1 reactor cores may be similarly configured to provide additional fuel assemblies that may be shuffled and/or included in larger inter-module fuel shuffling configurations.

The first batches of fuel 812, 822, 832 may be associated with the first reactor core 810, the second reactor core 820, and the third reactor core 830, respectively. The first fuel may comprise fresh fuel or new fuel. The second batches of fuel 814, 824, 844 may be associated with the first reactor core 810, the second reactor core 820, and the fourth reactor core 840, respectively. The second batch of fuel may comprise fuel that has been used or partially consumed during a previous fuel cycle. Further, third batches of fuel 816, 836, 846 may be associated with first reactor core 810, third reactor core 830, and fourth reactor core 840, respectively. The third batch of fuel may include fuel that has been used or partially consumed during two previous fuel cycles.

At the end of the fuel cycle associated with the fuel configuration shown in FIG. 8A, new or fresh fuel from a fuel source 880 may be added to the reactor core 810, 820, 830 to replace the fuel that has been removed. Additionally, the fourth batch of fuel 842 associated with the fourth reactor core 840 may be similarly replaced with new or fresh fuel 890, which may be added to the reactor core 840 to replace the fuel 842 that has been removed. In some examples, fuel 842 may be switched in a reverse direction from fourth reactor core 840 to third reactor core 830, as shown by the dashed lines. Similarly, fuel 834 may be switched in a reverse direction from the third reactor core 830 to the second reactor core 820.

Fuel source 890 may contain a different type of fuel than fuel source 880. In some examples, fuel source 880 may include a uranium oxide fuel and fuel source 890 may include a mixed uranium-plutonium oxide (MOX) fuel. Fuel from fuel source 880 may generally be understood to be shuffled between some or all of the reactor cores in a forward direction, while fuel from fuel source 890 may generally be understood to be shuffled between some or all of the reactor cores in a reverse direction.

At the end of the fuel cycle shown in fig. 8A, the fuels 816, 826, 836, 846 may be understood as having been used for three fuel cycles, and in some examples, may be further understood as having reached the end of their useful life. Accordingly, fuel originating from a fuel source 880, such as fuel 816, 836, 846, may be removed from the reactor core 810, 830, 840 and processed, reprocessed or stored in a first fuel storage facility 885, or otherwise disposed of. Similarly, at the end of the fuel cycle, fuel from the fuel source 890, such as fuel 826, may be removed from the second reactor core 820 and, in some examples, may be separately processed, reprocessed, or stored in the second fuel storage facility 895.

During the first fuel cycle, the four reactor cores 810, 820, 830, 840 may be operated with the fuel configuration shown in FIG. 8A. For example, the first reactor core 810 may be on-line or on-line with the fuel 812, 814, 816. Similarly, the second reactor core 820 may be on-line with fuels 822, 824, 826, the third reactor core 830 may be on-line with fuels 832, 834, 836, and the fourth reactor core 840 may be on-line with fuels 842, 844, 846. At the end of the first fuel cycle, some or all of the fuel may be switched between reactor cores.

FIG. 8B illustrates another example multi-way fuel shuffling configuration associated with subsequent fuel cycles. The fuel 812 may move from the first reactor core 810 to the second reactor core 820. However, although the fuel 834 is shown as having moved in a reverse direction from the third reactor core 830 to the second reactor core 820, the fuel 814 may move from the first reactor core 810 to the third reactor core 830, substantially skipping over the second reactor core 820. Additionally, although fuel 842 is shown as having moved in a reverse direction from fourth reactor core 840 to third reactor core 830, each of fuel 822 and fuel 824 may move from second reactor core 820 to fourth reactor core 840, thereby skipping over third reactor core 830.

At the end of the subsequent or second fuel cycle, fuel 872 may be moved from the third reactor core 830 to the fifth reactor core, and similarly fuel 822 may be moved from the fourth reactor core 840 to the fifth reactor core. A fifth reactor core may be associated with a second set of four reactor cores, which are similarly arranged as reactor cores 810, 820, 830, 840. In some examples, there may be three or more sets of reactor cores, each set of reactor cores including four reactor cores.

On the other hand, in a multi-module power plant consisting of four reactor cores, fuel 872 may be moved from the third reactor core 830 to the first reactor core 810 (core location shown as including fuel 892), and fuel 822 may be moved from the fourth reactor core 840 to the first reactor core 810 (core location shown as including fuel 894). In some examples, the fuel may be switched in a closed loop or circular pattern, with unspent fuel moving between the four reactor cores at the end of each subsequent fuel cycle.

As described above, an exemplary fuel loading configuration in which a main batch of fuel from fuel source 880 proceeds through a reactor core in a forward direction may be supplemented with an n +1 batch of fuel from fuel source 890, which may be reversed back through the reactor core. The new fuel with the greatest excess reactivity may be combined with other batches of fuel with moderate to low excess reactivity. For example, when excess reactivity in 890 fuel decreases, the n +1 batches of fuel may be switched back into one or more cores associated with fuels having medium and high excess reactivity.

The characteristics of the n +1 batches of fuel may be selected to capture the remaining energy output in the underutilized fuel to help achieve favorable in-core neutron or power distribution characteristics, to burn MOX fuel as part of the fuel used in the power plant, or any combination thereof. In addition to producing an improvement in overall fuel consumption, the exemplary inter-module switching process can be optimized to reduce the number of fuel cycles required to process the existing plutonium inventory.

In a twelve-module or other type of multi-module and/or multi-core power plant, the fuel assemblies may be rearranged, moved, or otherwise selected from spent fuel pools and/or reactor modules based on a number of criteria or characteristics. As non-exhaustive examples, the features may include: 1) having more excess reactivity available to reduce enrichment (cost) of fresh fuel load, 2) having exposure or excess reactivity characteristics that are compatible with other components in the module for power peak and fuel utilization optimization, and/or 3) components that may be considered to be completely "depleted" in a single module reload scheme may be combined with fresh fuel having sufficient excess reactivity so that the fuel components may be used in additional cycles.

As described above, inter-module fuel shuffling may also benefit in hybrid fuel source paradigms, such as dual fuel utilization of MOX and UO 2. In addition to the aforementioned benefits, inter-module fuel shuffling can deplete MOX fuel assemblies more quickly and more fully. For example, the MOX inventory may be depleted in a more convenient manner while also achieving maximum energy output.

In some examples, the first core loaded with MOX, such as the fourth reactor core 840, may result in a high initial depletion of fuel for the lot with the greatest excess reactivity, so it will burn first. By maintaining the fuel in the reactor core for three cycles, burn-up of the MOX fuel assembly can be maximized.

FIG. 8C illustrates yet another example multi-way fuel shuffling configuration associated with subsequent fuel cycles. The configuration shown in fig. 8C differs from the configuration shown in fig. 8B in that fuel 834, previously located in third reactor core 830 (see fig. 8A), has been shuffled back to first reactor core 810 instead of second reactor core 820. Additionally, in contrast to fig. 8B, since the second reactor core 820 is no longer being fueled in the aft direction from the third reactor core 830, the fuel 894 may move forward into the second reactor core 820, rather than into the first reactor core 810.

Additional exemplary Fuel configurations

An exemplary fuel loading system, configuration and/or refueling method may additionally be understood from the following description with reference to fig. 8A-8C. The first reactor core 810 may include a first fuel loading configuration including a first fuel assembly 812 associated with a first batch of fuel and a first portion of spent fuel assemblies 814 associated with a second batch of fuel.

The second reactor core 820 may include a second fuel loading configuration including a second fuel assembly 822 associated with a first batch of fuel and a second portion of spent fuel assemblies 824 associated with a second batch of fuel. After the previous fuel cycle, a second portion of the spent fuel assemblies 824 may have been removed from the first reactor core 820 and transported to a fuel storage facility. Additionally, the second reactor core 820 may include a third cycle fuel assembly 826 that includes a portion of spent nuclear fuel that has previously completed two fuel cycles.

The third reactor core 830 may include a third fuel loading configuration including a third fuel assembly 832 associated with the first batch of fuel and a third portion of spent fuel assemblies 834 that replace the third circulating fuel assembly 826 moved from the third reactor core 830 to the second reactor core 820. In some examples, the third circulation fuel assembly 826 may be removed from the third reactor core 830 after a previous fuel circulation and transported to the second fuel storage facility 895 before being inserted into the second reactor core 820.

The fourth reactor core 840 may include a fourth fuel loading configuration including a fourth fuel assembly 842 selected from a fourth batch of fuel. The fourth batch of fuel may include fresh fuel obtained from the fuel source 890. In some examples, the fourth fuel assembly 842 may have replaced the third portion of the spent fuel assemblies 834 moved from the fourth reactor core 840 to the third reactor core 830 after the previous fuel cycle.

One or more fuel loading configurations may be rearranged during a subsequent fuel cycle. For example, the second fuel configuration associated with the second reactor core 820 may be updated to include a fourth fuel assembly 842 for a subsequent fuel cycle, as shown in dashed lines in fig. 8B. Similarly, a fourth fuel configuration associated with the fourth reactor core 840 may be updated to include the second portion of the spent fuel assembly 812 for a subsequent fuel cycle.

While the exemplary configurations and processes have shown various configurations of forward and backward shuffling, including fuel shuffling techniques that can "skip" adjacent reactor cores in one or more situations in either direction, other exemplary fuel shuffling techniques and modes are contemplated herein. For example, different fuel batches may follow different patterns or alternate between fuel loading patterns, such as a combination of the configurations shown in fig. 8A and 8B. Similarly, different numbers and combinations of batches, reactor cores, fuel types, and/or fuel cycles may be employed to further vary the fuel shuffling combinations.

Still further, while several of the illustrated examples generally show fuel being shuffled between reactor cores, in some examples, a combination of inter-module and intra-module fuel shuffling may be performed. For example, fuel from a first section of one reactor core may move into a second section of the same reactor core, while fuel from a second section of the reactor core may be transposed to another reactor core.

In an isolated or single reactor core of a conventional power plant, the core designer may be limited by the number of components that can be installed and the number of locations where existing components can be swapped, as compared to the exemplary multi-module reactor plant with inter-module fuel swapping described above. The small number of components limits the ability to efficiently distribute the various exposed or excessively reactive components without challenging power peak limits and other challenges to reactivity limits.

By providing an inter-module shuffling process as described by the various exemplary configurations and processes described herein, the number of fuel locations and shuffling, and possible arrangements, can be greatly increased.

Reactor startup fuel configuration

The fuel configuration 800 shown in fig. 8A may also be optimized for initial reactor startup operations, such as the first time the reactor plant is on-line. New fuels 812, 822, 832, and 842 are available from fuel sources 880 and 890, respectively. However, since reactor startup may be the first time that some or all of the reactor cores 810, 820, 830, 840 are online, additional batches of fuel (e.g., second and/or third batches) may also not have been previously used in any of the reactor cores 810, 820, 830, 840. In other examples, less than all of the reactor cores 810, 820, 830, 840 may be initially operated, and the remaining reactor cores may be added later or online to provide supplemental power as energy demand increases over time.

To facilitate startup of the reactor core and achieve similar reactivity and power curves as if all of the reactor cores of the power plant had been operating in multiple fuel cycles, some of the fuel assemblies in the second and third batches may include reduced activity levels or reduced fuel content to simulate a portion of spent fuel. For example, some fuel assemblies may be manufactured as start-up fuel assemblies that include different amounts of uranium or different concentrations of concentrate to replicate portions of spent fuel.

By introducing a startup fuel assembly into a reactor core that can be started up for the first time, the fuel configuration can behave similarly to a fuel configuration that includes a portion of spent fuel that has been switched over in two or more fuel cycles. Thus, the reactor core may be online during the first start-up in a similar manner as a subsequent plant start-up, which may occur after a refueling operation after the power plant runs a certain number of fuel cycles.

In some examples, one or more fuel cycles may be staggered, such as by performing a startup difference between reactor cores to produce a plurality of fuel batch sequences. In other examples, half of the reactor core's fuel may be turned between modules after a fuel cycle, and the other half of the reactor core's fuel may be turned between modules after the same fuel cycle. In addition, a portion of the spent fuel may be temporarily stored in the fuel storage facility during a subsequent fuel cycle so that the fuel may skip the fuel cycle and then be reintroduced into the fuel shuffling program in order to provide fuel batches having a different number of fuel cycles in use.

In other examples, different numbers of fuel cycles may be associated with different reactor cores. For example, fuel for a first set of reactor cores may be associated with three fuel cycles, and fuel for a second set of reactor cores may be associated with four fuel cycles. The length of each fuel cycle may vary between groups of reactor cores so that the total usable life of the fuel is the same.

In addition, the different amounts of reactivity that may be experienced during start-up and/or during operation of the new power plant may be controlled by adjusting the position of one or more control rods within the reactor core and/or by changing the chemical composition of the primary coolant (e.g., by adding boron) to change the number of fission events or the criticality of the reactor core.

After months or years from reactor startup, fuel batches in all reactor cores may be shuffled among all on-line reactor cores in a manner similar to one or more inter-module fuel shuffling techniques described herein.

FIG. 9 illustrates an example system 900 associated with loading fuel in a plurality of reactor cores. The system 900 may include a plurality of reactor cores, including a first reactor core 910, a second reactor core 920, a third reactor core 930, a fourth reactor core 940, and one or more additional reactor cores 970. In some examples, some or all of the reactor cores 910, 920, 930, 940 may be associated with a first set of reactor cores, and the additional reactor core 970 may be associated with two or more additional sets of reactor cores. The additional sets of reactor cores may be constructed similarly to the first set of reactor cores.

The fuel storage facility 960 may be configured to store a number of fuel assemblies associated with a plurality of on-site reactor cores. The fuel storage facility may include a common spent fuel storage pool fluidly coupled to a plurality of reactor bays housing a plurality of on-site reactor cores.

The transport equipment 950 may be configured to transport the spent fuel assemblies to a fuel storage facility 960. In some examples, the transport apparatus 950 may include a crane configured to transport one or more reactor cores from a plurality of reactor bays to a re-fueling station located near the fuel storage facility 960. Additionally, the transport equipment 950 may include automated, semi-automated, and/or remote fuel processing equipment configured to add, remove, replace, and/or otherwise process new and spent fuel.

The transport apparatus 950 may be configured to transport portions of spent fuel assemblies to the fuel storage facility 960 and/or to replace one or more portions of spent fuel assemblies of a reactor core located in a re-fueling station, where one or more other portions of spent fuel assemblies are located in the fuel storage facility 960 that have been previously removed from other on-site reactor cores.

Storage device 990 may have instructions stored thereon that, in response to execution by processing device 980, cause processing device 980 and/or transport apparatus 950 to perform one or more operations. For example, the operations may include: for a first fuel cycle, a first fuel configuration associated with a first reactor core 910 is determined. The first fuel configuration may include a first fuel assembly selected from a first batch of fuel and a first portion of spent fuel assemblies selected from a second batch of fuel.

The operations may further include: for the first fuel cycle, a second fuel configuration associated with the second reactor core 920 is determined. The second fuel configuration may include a second fuel assembly selected from the first batch of fuel and a second portion of the spent fuel assembly selected from the second batch of fuel.

Additionally, the operations may include: for a second fuel cycle conducted after the first fuel cycle is completed, the second fuel configuration associated with the second reactor core 920 is updated to include fresh fuel assemblies and first fuel assemblies selected from the first batch of fuel.

In some examples, a third fuel configuration associated with the third reactor core 930 may also be determined for the first fuel cycle. The third fuel configuration may include a third fuel assembly selected from the first group of fuels and a third portion of the spent fuel assembly. The second fuel configuration may be updated for the second fuel cycle by updating the second fuel configuration to include a third portion of the spent fuel assembly.

Further, the operations may include: for the first fuel cycle, a fourth fuel configuration associated with the fourth reactor core 940 is determined, including a fourth fuel assembly selected from a fourth batch of fuel. In some examples, a third fuel configuration associated with a third reactor core may be updated for the second fuel cycle to include a fourth fuel assembly.

During the third fuel cycle, the operations may include: the second fuel configuration associated with the second reactor core 920 is updated to include the fourth fuel assembly and the fourth fuel configuration associated with the fourth reactor core 940 is updated to include the second portion of the spent fuel assemblies.

Fig. 10 illustrates an example fuel shuffling process 1000 for multiple reactor cores associated with multiple fuel cycles. In some examples, one or more of the example operations 1010-1060 may be understood to be associated with a first fuel cycle. Additionally, one or more of the example operations 1070-1090 may be understood to be associated with the second fuel cycle. Other example operations described herein may additionally be associated with the third fuel cycle, additional fuel cycles, or any combination thereof.

In a first fuel cycle, at operation 1010, a first reactor core may be loaded with a first fuel assembly selected from a first batch of fuel. Additionally, at operation 1020, the first reactor core may be loaded with a first portion of spent fuel assemblies from the second batch of fuel. At operation 1030, the second reactor core may be loaded with second fuel assemblies from the first batch of fuel, and at operation 1040, the second reactor core may be loaded with a second portion of spent fuel assemblies from the second batch of fuel.

In some exemplary operations associated with the first fuel cycle, such as operation 1050, the third reactor core may be loaded with a third fuel assembly selected from the first batch of fuel. Additionally, at operation 1060, a third reactor core may be loaded with a third portion of spent fuel assemblies. In some examples, the third fuel assembly may include nuclear fuel having at least one isotope of uranium, and the third portion of the spent fuel assembly may include nuclear fuel having at least one isotope of plutonium.

In a second fuel cycle performed after completion of the first fuel cycle, operation 1070 may include loading the second reactor core with fresh fuel assemblies. At operation 1080, a second reactor core may additionally be loaded with first fuel assemblies from the first batch of fuel. In some examples, a second reactor core may be loaded with a first fuel assembly by removing the first fuel assembly from the first reactor core and replacing a second portion of the spent fuel assembly with the first fuel assembly.

In some exemplary operations associated with the second fuel cycle, such as operation 1090, the second reactor core may be loaded with a third portion of the spent fuel assembly. In an exemplary operation in which the first portion of the spent fuel assemblies may be removed from the first reactor core after the first fuel cycle is completed, the third reactor core may be loaded with the first portion of the spent fuel assemblies in the second fuel cycle.

In examples including four or more reactor cores, a fourth reactor core may be loaded with a fourth fuel assembly selected from a fourth batch of fuel in the first fuel cycle. The third reactor core may be loaded with a fourth fuel assembly in the second fuel cycle. In some examples, the first batch of fuel may include fuel associated with a first nuclear isotope and the fourth batch of fuel may include fuel associated with a second nuclear isotope different from the first nuclear isotope. As a further non-exhaustive example, the first fuel batch may comprise a uranium oxide (UO2) fuel and the fourth fuel batch may comprise a mixed uranium-plutonium oxide (MOX) fuel.

The third reactor core may be loaded with a fourth fuel assembly by removing a third portion of the spent fuel assemblies from the third reactor core and replacing the third portion of the spent fuel assemblies with the fourth fuel assembly.

In an exemplary fuel cycle including removing a second portion of the spent fuel assemblies from the second reactor core and removing a fourth fuel assembly from the third reactor core, operations associated with the subsequent or third fuel cycle may include loading the second reactor core with the fourth fuel assembly and loading the fourth reactor core with the second portion of the spent fuel assembly.

One or more of the example systems described herein may include various nuclear reactor technologies and may include and/or be used in connection with nuclear reactors that use uranium oxide, uranium hydride, uranium nitride, uranium carbide, mixed oxides, uranium silicide, thorium-based fuels (such as thorium-plutonium or uranium-thorium), zirconium-uranium metal fuels, advanced accident-tolerant fuels, and/or other types of fuels. Although the examples provided herein primarily describe pressurized water reactors and/or light water reactors, the examples may be applied to other types of power systems. For example, these examples and variations thereof may also be operable with boiling water reactors, sodium liquid metal reactors, gas cooled reactors, pebble bed reactors, and/or other types of reactor designs.

Additionally, the examples illustrated herein are not necessarily limited to any particular type of reactor cooling mechanism, nor to any particular type of fuel used to generate heat within or associated with a nuclear reaction. Any ratios and values described herein are exemplary only. Other ratios and values may be determined experimentally, for example by constructing a full-scale or proportional model of the nuclear reactor system.

While various examples have been described and illustrated herein, it should be apparent that other examples may be modified in arrangement and detail. We claim all modifications and variations coming within the spirit and scope of the following claims.

Claims (20)

1. A method of loading fuel in a plurality of reactor cores associated with a plurality of fuel cycles, the method comprising:

in the first fuel cycle:

loading a first reactor core with a first fuel assembly selected from a first batch of fuel;

loading the first reactor core with a first portion of spent fuel assemblies from a second batch of fuel;

loading a second reactor core with a second fuel assembly from the first batch of fuel; and

loading the second reactor core with a second portion of spent fuel assemblies from the second batch of fuel; and

in a second fuel cycle executed after completion of the first fuel cycle,

loading the second reactor core with fresh fuel assemblies; and

loading the second reactor core with the first fuel assembly from the first batch of fuel.

2. The method of claim 1, wherein loading the second reactor core with the first fuel assembly comprises:

removing the first fuel assembly from the first reactor core; and

replacing the second portion of the spent fuel assembly with the first fuel assembly.

3. The method of claim 1, further comprising:

in the first fuel cycle:

loading a third reactor core with a third fuel assembly selected from the first batch of fuel; and

loading the third reactor core with a third portion of spent fuel assemblies; and

loading the second reactor core with the third portion of spent fuel assemblies in the second fuel cycle.

4. The method of claim 3, further comprising:

loading a fourth reactor core with a fourth fuel assembly selected from a fourth batch of fuel in the first fuel cycle; and

loading the third reactor core with the fourth fuel assembly in the second fuel cycle.

5. The method of claim 4, wherein the first batch of fuel comprises fuel associated with a first nuclear isotope, and wherein the fourth batch of fuel comprises fuel associated with a second nuclear isotope different from the first nuclear isotope.

6. A method according to claim 5 in which the first fuel comprises a uranium oxide (UO2) fuel and in which the fourth fuel comprises a mixed uranium-plutonium oxide (MOX) fuel.

7. The method of claim 4, wherein loading the third reactor core with the fourth fuel assembly comprises:

removing the third portion of the spent fuel assemblies from the third reactor core; and

replacing the third portion of the spent fuel assembly with the fourth fuel assembly.

8. The method of claim 4, further comprising:

removing the second portion of the spent fuel assemblies from the second reactor core;

removing the fourth fuel assembly from the third reactor core; and

in a third fuel cycle:

loading the second reactor core with the fourth fuel assembly; and

loading the fourth reactor core with the second portion of the spent fuel assembly.

9. A method according to claim 3, wherein the third fuel assembly includes nuclear fuel having at least one isotope of uranium, and wherein the third portion of the spent fuel assembly includes nuclear fuel having at least one isotope of plutonium.

10. The method of claim 3, further comprising:

removing the first portion of spent fuel assemblies from the first reactor core after the first fuel cycle is complete; and

loading the third reactor core with the first portion of spent fuel assemblies in the second fuel cycle.

11. A fuel loading system, comprising:

a fuel storage facility configured to store a number of fuel assemblies associated with a plurality of on-site reactor cores;

a transportation apparatus configured to transport spent fuel assemblies to the fuel storage facility;

a first reactor core comprising a first fuel loading configuration, the first fuel loading configuration comprising:

a first fuel assembly associated with a first batch of fuel; and

a first portion of spent fuel assemblies associated with a second batch of fuel;

a second reactor core comprising a second fuel loading configuration, the second fuel loading configuration comprising:

a second fuel assembly associated with the first batch of fuel;

a second portion of spent fuel assemblies associated with the second batch of fuel, wherein the second portion of spent fuel assemblies are removed from the first reactor core and transported to the fuel storage facility after a previous fuel cycle; and

a third cycle fuel assembly comprising a portion of spent nuclear fuel that has previously completed two fuel cycles; and

a third reactor core comprising a third fuel loading configuration comprising:

a third fuel assembly associated with the first batch of fuel; and

a third portion of spent fuel assemblies replacing the third circulating fuel assemblies in the third reactor core, wherein the third circulating fuel assemblies are removed from the third reactor core and transported to the fuel storage facility after a previous fuel cycle.

12. The fuel loading system of claim 11, wherein the transport apparatus is configured to:

transporting the second portion of spent fuel assemblies to the fuel storage facility prior to loading the second portion of spent fuel assemblies into a second reactor; and

transporting the third portion of spent fuel assemblies to the fuel storage facility prior to loading the third portion of spent fuel assemblies to the second reactor.

13. The fuel loading system according to claim 11, wherein the fuel storage facility includes a common spent fuel storage pool fluidly coupled to a plurality of reactor bays housing the plurality of on-site reactor cores, and wherein the transport apparatus includes a crane configured to transport one or more reactor cores from the plurality of reactor bays to a re-fueling station located proximate the common spent fuel storage pool.

14. The fuel loading system according to claim 13, wherein the transport apparatus is further configured to replace one or more partial spent fuel assemblies of the reactor core located in the re-fueling station with one or more other partial spent fuel assemblies located in the common spent fuel storage pool that have been previously removed from other on-site reactor cores.

15. The fuel loading system according to claim 11, further comprising a fourth reactor core comprising a fourth fuel loading configuration comprising a fourth fuel assembly selected from a fourth batch of fuel, wherein the fourth fuel assembly replaces the third portion of spent fuel assemblies in the fourth reactor core after a previous fuel cycle.

16. The fuel loading system of claim 15, updated for a subsequent fuel cycle, comprising:

an updated second fuel configuration associated with the second reactor core to include the fourth fuel assembly for a subsequent fuel cycle; and

an updated fourth fuel configuration associated with the fourth reactor core to include the second portion of spent fuel assemblies for a subsequent fuel cycle.

17. A storage device having instructions stored thereon that, in response to execution by a processing device, cause the processing device to perform operations comprising:

for a first fuel cycle, determining a first fuel configuration associated with a first reactor core, wherein the first fuel configuration includes a first fuel assembly selected from a first batch of fuel and a first portion of spent fuel assemblies selected from a second batch of fuel; and

determining, for the first fuel cycle, a second fuel configuration associated with a second reactor core, wherein the second fuel configuration includes a second fuel assembly selected from the first batch of fuel and a second portion of spent fuel assemblies selected from the second batch of fuel; and

updating the second fuel configuration associated with the second reactor core to include fresh fuel assemblies and the first fuel assemblies selected from the first batch of fuel for a second fuel cycle implemented after completion of the first fuel cycle.

18. The storage device of claim 17, wherein the operations further comprise: determining, for the first fuel cycle, a third fuel configuration associated with a third reactor core, wherein the third fuel configuration includes a third fuel assembly selected from the first batch of fuel and a third portion of spent fuel assemblies, and wherein updating the second fuel configuration for the second fuel cycle further includes updating the second fuel configuration to include the third portion of spent fuel assemblies.

19. The storage device of claim 18, wherein the operations further comprise:

determining, for the first fuel cycle, a fourth fuel configuration associated with a fourth reactor core, the fourth fuel configuration comprising a fourth fuel assembly selected from a fourth batch of fuel; and

updating the third fuel configuration associated with the third reactor core to include the fourth fuel assembly for the second fuel cycle.

20. The storage device of claim 19, wherein the operations further comprise:

for a third fuel cycle, updating the second fuel configuration associated with the second reactor core to include the fourth fuel assembly; and

for the third fuel cycle, updating the fourth fuel configuration associated with the fourth reactor core to include the second portion of spent fuel assemblies.