Patent Description:
Power plants, such as those that employ a nuclear reactor, generate electrical power. Most of the generated power is transmitted to remote consumers. However, a portion of the generated electrical power is locally distributed to the power plant. The locally distributed power is used to operate the plant and provide safety-related functionality. More specifically, the locally distributed power is used to power the various electrical, mechanical, and/or pneumatic/hydraulic systems that are needed to run and ensure the efficient and safe generation of power.

In conventional designs for nuclear reactor plants, locally distributed electrical power is required to perform safety-related functions under normal conditions and to safely shutdown various systems following a loss of alternating current (AC) power. Power plants may employ Class IE direct current (DC) components and systems for such safety-related tasks. Such Class IE DC systems are typically required to remain operational when the power plant is generating power. Accordingly, in conventional plant designs, maintaining Class IE hardware, when the plant is generating power, may involve considerable risk to the plant and/or plant personnel. To ensure that safety-related functions remain operational when the plant is generating power and decrease risk to the plant personnel, best practices in conventional plant designs involve maintaining Class IE hardware during plant outages. It is for these and other concerns that the following disclosure is provided.

<CIT> describes an electrical power system for a nuclear power facility that includes an active alternating current (AC) power bus configured to be electrically coupled to a plurality of engineered safety feature (ESF) loads.

According to the invention, a fault-tolerant power plant system is provided in accordance with the claims appended hereto. The invention is solely defined by the features of the independent claim <NUM>.

Various embodiments are directed towards fault-tolerant direct current (DC) electrical power-distribution modules (PDM). PDMs provide DC power signals to various critical and non-critical plant loads within a power plant. The critical plant loads may include safety-related loads. Various embodiments of PDMs may be considered a non-Class IE component. A PDM, as disclosed herein, reduces the likelihood of unintended triggering of a safety-related system actuation in the event of a loss of DC power. Accordingly, various embodiments of PDMs reduce the likelihood of the power plant experiencing a loss in DC power. The fault-tolerance enables flexibility to perform system maintenance activities, even when the power plant (and a PDM) is generating and/or providing electrical power. In a least one embodiment, a PDM supplies or provides a <NUM> V DC power signal to various module specific or common plant electrical loads.

In various embodiments in accordance with the invention as claimed herein, a PDM is a module-specific PDM. In an alternative case, not part of the claimed invention but which where discussed below may clarify features of the invention, a PDM may be a common plant PDM. Both module-specific and common plant PDMs are fault-tolerant and include redundancy such that any component may be removed from service during normal plant operation and without loss of overall PDM function.

In various embodiments, a fault-tolerant PDM supplies electrical power, which is generated within a power plant, to plant loads within the power plant. The PDM may include inputs, a first DC bus, a second DC bus, a first channel, and a second channel. The inputs are coupled to alternating current (AC) busses of the power plant and provide an AC signal to the module. The first DC bus is coupled to a first load separation group (LSG) of the plant loads. The second DC bus is coupled to a second LSG of the plurality of plant loads.

When at least one of the AC busses provides the AC signal to the first channel, a first rectifier rectifies the AC signal and selectively provides a first DC signal to the first DC bus. The first DC signal includes a first portion of the rectified AC signal. When the AC busses do not provide the AC signal to the first channel, a first battery selectively provides the first DC signal to the first DC bus. The first DC signal includes energy stored in the first battery.

When at least one of the AC busses provide the AC signal to the second channel, a second rectifier rectifies the AC signal and selectively provides a second DC signal to the second DC bus. The second DC signal includes a second portion of the rectified AC signal. When the AC busses do not provide the AC signal to the second channel, a second battery selectively provides the second DC signal to the second DC bus. The second DC signal includes energy stored in the second battery.

In some embodiments, the module further includes a third DC bus, a fourth DC bus, a third channel, and a fourth channel. The third DC bus is coupled to a third LSG of the plant loads. The fourth DC bus is coupled to a fourth LSG of the plant loads. When at least one of the AC busses provides the AC signal to the third channel, a third rectifier rectifies the AC signal and selectively provides a third DC signal to the third DC bus. The third DC signal includes a third portion of the rectified AC signal. When the AC busses do not provide the AC signal to the third channel, a third battery selectively provides the third DC signal to the third DC bus. The third DC signal includes energy stored in the third battery.

When at least one of the AC busses provide the AC signal to the fourth channel, a fourth rectifier rectifies the AC signal and selectively provides a fourth DC signal to the fourth CD bus. The fourth DC signal includes a fourth portion of the rectified AC signal. When the AC busses do not provide the AC signal to the fourth channel, a fourth battery selectively provides the fourth DC signal to the fourth DC bus. The fourth DC signal includes energy stored in the fourth battery.

In at least one embodiment, when at least one of the AC busses provide the AC signal to the first channel, a third rectifier rectifies the AC signal and selectively provides a third DC signal to the first DC bus. The third DC signal includes a third rectified portion of the AC signal. When the plurality of AC busses do not provide the AC signal to the first channel, a third battery selectively provides the third DC signal to the first DC bus. The third DC signal includes energy stored in the third battery.

When at least one of the AC busses provide the AC signal to the second channel, a fourth rectifier rectifies the AC signal and selectively provides a fourth DC signal to the second DC bus. The fourth DC signal includes a fourth portion of the rectified AC signal. When the AC busses do not provide the AC signal to the second channel, a fourth battery selectively provides the fourth DC signal to the second DC bus. The fourth DC signal includes energy stored in the fourth battery.

In some embodiments, a capacity of the first battery enables the first battery to provide the first DC signal to the first LSG for at least <NUM> hours. A capacity of the second battery enables the second battery to provide the second DC signal to the second LSG for at least <NUM> hours. A capacity of the third battery enables the third battery to provide the third DC signal to the third LSG for at least <NUM> hours. A capacity of the fourth battery enables the fourth battery to provide the fourth DC signal to the fourth LSG for at least <NUM> hours.

In at least one embodiment, the first channel includes a first battery charger. When at least one of the AC busses provide the AC signal to the first channel, the first battery charger selectively charges the first battery and maintains a float voltage on the first battery. The second channel includes a second battery charger. When at least one of the plurality of AC busses provide the AC signal to the second channel, the second battery charger selectively charges the second battery and maintains the float voltage on the second battery.

In some embodiments, the module may further include a first switch and a second switch. The first switch selectively couples the first DC bus and the first battery. The second switch that selectively couples the second DC bus and the second battery. At least a portion of each of the first and the second DC busses may be included in one or more switchgear modules.

Some embodiments include a fault-tolerant system. The system locally provides electrical power generated in a power plant to the power plant. The system include AC inputs, a first channel, and a second channel. The AC inputs are each enabled to receive an AC signal. The first channel includes a first sub-system, a second sub-system, and a first DC bus. The second channel includes a third sub-system, a fourth sub-system, and a second DC bus.

In response to receiving the AC signal from at least one of the plurality of AC inputs, the first sub-system generates a first DC signal. In response to receiving the AC signal from the at least one of the plurality of AC inputs, the second sub-system generates a second DC signal. In response to receiving at least one of the first or the second DC signals from the first or the second sub-systems, the first DC bus provides the received first or the second DC signals to a first subset of the plant loads.

In response to receiving the AC signal from at least one of the plurality of AC inputs, the third sub-system generates a third DC signal. In response to receiving the AC signal from at least one of the plurality of AC inputs, the fourth sub-system generates a fourth DC signal. In response to receiving at least one of the third or the fourth DC signals from the third or the fourth sub-systems, the second DC bus provides the received third or the fourth DC signals to the first subset of the plant loads.

At least one embodiment includes a third channel and a fourth channel. The third channel includes a fifth sub-system, a sixth sub-system, and a third DC bus. The fourth channel includes a seventh sub-system, an eighth sub-system, and a fourth DC bus. In response to receiving the AC signal from at least one of the plurality of AC inputs, the fifth sub-system generates a fifth DC signal. In response to receiving the AC signal from at least one of the plurality of AC inputs, the sixth sub-system generates a sixth DC signal. In response to receiving at least one of the fifth or the sixth DC signals from the fifth or the sixth sub-systems, the third DC bus provides the received fifth or the sixth DC signals to a second subset of the plant loads.

In response to receiving the AC signal from at least one of the plurality of AC inputs, the seventh sub-system generates a fourth DC signal. In response to receiving the AC signal from at least one of the AC inputs, the eighth sub-system generates an eighth DC signal. In response to receiving at least one of the seventh or the eighth DC signals from the seventh or the eighth sub-systems, the fourth DC bus provides the received seventh or the eighth DC signals to the second subset of the plurality of plant loads.

In various embodiments, the first sub-system of the first channel includes a first battery and a first charging module. The second sub-system of the first channel may include a second battery and a second charging module. In response to the first sub-system receiving the AC signal from the AC bus, the first charging module generates the first DC signal by converting at least a portion of the AC signal to the first DC signal. The first charging module employs a portion of the first DC signal to charge and maintain a float voltage on the first battery and provides another portion of the first DC signal to the first DC bus. In response to the second sub-system receiving the AC signal from the AC bus, the second charging module generates the second DC signal by converting at least a portion of the AC signal to the second DC signal. The second charging module also employs a portion of the second DC signal to charge and maintain a float voltage on the second battery, and provides another portion of the second DC signal to the first DC bus.

In at least one embodiment, in response to the first sub-system not receiving the AC signal from the AC bus, the first battery selectively generates the first DC signal and selectively provides the first DC signal to the first DC bus. In response to the second sub-system not receiving the AC signal from the AC bus, the second battery selectively generates the second DC signal and selectively provides the second DC signal to the first DC bus.

In various embodiments, the first sub-system of the first channel includes a first battery, a first charging module, and a first switch. The first switch selectively couples and decouples the first DC bus and the first battery. The second sub-system of the first channel includes a second battery, a second charging module, and a second switch. The second switch selectively couples and decouples the second DC bus and the second battery. A voltage of the AC signal may be approximately <NUM> V AC. A voltage of the first and the second DC signals may be approximately <NUM> V. The AC signal may be generated from heat generated by a nuclear reactor included in the power plant. The first subset of the plant loads is employed to operate the nuclear reactor. Furthermore, the second subset of the plan loads may be employed to operate the nuclear reactor.

Various embodiments include a fault-tolerant power supply that supplies direct current (DC) power to plants loads within a nuclear power plant. The power supply may include alternating current (AC) inputs and a first supply subdivision. A local distribution bus of the power plant provides one or more AC signals to the AC inputs. The first supply subdivision includes a first battery, a second battery, a first battery charger, a second battery charger, and a first DC bus. The first DC bus is enabled to provide a first DC signal to a first subset of the plant loads. When at least one of the AC inputs provides the AC signal to the first supply subdivision, at least one of the first or the second battery chargers employs the AC signal to at least provide the first DC signal to the first DC bus. When the AC inputs do not provide the AC signal to the first supply subdivision, at least one of the first or the second batteries selectively provides the first DC signal to the first DC bus.

Some embodiments of the power supply further include a first switch and a second switch. The first switch selectively couples and decouples at least one of the AC busses and the first battery charger. When the at least one of the AC busses and the first battery charger are coupled, the at least one of the AC busses is enabled to provide the AC signal to first battery charger. The first battery charger is enabled to employ the AC signal to provide the first DC signal to the first DC bus. The second switch selectively couples and decouples at least one of the AC busses and the second battery charger. When the at least one of the AC busses and the second battery charger are coupled, the at least one of the AC busses is enabled to provide the AC signal to second battery charger. The second battery charger is enabled to employ the AC signal to provide the first DC signal to the first DC bus.

In some embodiments, the power supply also includes a second supply division. The second supply subdivision includes a third battery, a fourth battery, a third battery charger, a fourth battery charger, and a second DC bus. The second DC bus is enabled to provide a second DC signal to the second subset of the plant loads. When at least one of the AC busses provides the AC signal to the second supply subdivision, at least one of the third or the fourth battery chargers employs the AC signal to at least provide the second DC signal to the second DC bus. When the AC busses do not provide the AC signal to the second supply division, at least one of the third or the fourth batteries selectively provides the second DC signal to the second DC bus.

Some embodiments of the power supply include a first switch and a second switch. The first switch selectively couples and decouples at least one of the AC busses and the first supply subdivision. When the at least one of the AC busses and the first supply subdivision are coupled, the at least one of the AC busses is enabled to provide the AC signal to at least one of the first or the second battery chargers. The at least one of the first or the second battery chargers is enabled to employ the AC signal to provide the first DC signal to the first DC bus. The second switch selectively couples and decouples at least one of the AC busses and the second supply subdivision. When the at least one of the AC busses and the second supply subdivision are coupled, the at least one of the AC busses is enabled to provide the AC signal to at least one of the third or the fourth battery charger. The at least one of the third or the fourth battery charger is enabled to employ the AC signal to provide the second DC signal to the second DC bus.

In other embodiments, the first switch selectively couples and decouples the first battery and the first battery charger. When the at least one of the AC busses provides the AC signal to the first supply subdivision and the first battery is coupled to the first battery charger, the first battery charger is enabled to at least charge the first battery or maintain a float voltage on the first battery. The second switch selectively couples and decouples the second battery and the second battery charger. When the at least one of the AC busses provides the AC signal to the second supply subdivision and the second battery is coupled to the second battery charger, the second battery charger is enabled to at least charge the battery or maintain the float voltage on the second battery. In at least one embodiment, the power supply further includes a second supply subdivision. The second supply division includes a third battery, a fourth battery, a third battery charger, a fourth battery charger, and a second DC bus.

Preferred and alternative examples not necessarily claimed as the present invention are described in detail below with reference to the following drawings:.

Various embodiments and examples not being claimed embodiments are described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific embodiments by which the invention may be practiced. The embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art. Among other things, the various embodiments may be methods, systems, media, or devices. Accordingly, the various embodiments may be entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. The following detailed description should, therefore, not be limiting.

Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The term "herein" refers to the specification, claims, and drawings associated with the current application. The phrase "in one embodiment" as used herein does not necessarily refer to the same embodiment, though it may. Furthermore, the phrase "in another embodiment" as used herein does not necessarily refer to a different embodiment, although it may.

However, the embodiments in this disclosure are not necessarily embodiments of the invention which is defined by the scope of independent claim <NUM>.

In addition, as used herein, the term "or" is an inclusive "or" operator, and is equivalent to the term "and/or," unless the context clearly dictates otherwise. The term "based on" is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on.

As used herein, the term "switchgear" is used to indicate various electrical distribution components and/or hardware, such as but not limited to switches, fuses, and circuit breakers. A "switchgear module" is a module that includes a plurality of switchgear components and a switchgear module bus. A switchgear module may include one or more inputs electrically coupled to one or more outputs, via the switchgear module bus. As discussed throughout and shown in the various figures, various switchgear components, such as switches, circuit breakers, fuses, and such may be included in a switchgear module and intermediate the inputs and outputs of the switchgear module.

Briefly stated, embodiments are directed to fault-tolerant power-distribution modules (PDM). A PDM may be included in a modular power plant to provide a portion of the power generated by the plant as direct current (DC) electrical power for the operation of the plant. A fault-tolerant power-distribution system may distribute a portion of the power generated by the plant to one or more PDMs. The PDMs provide electrical power to various plant loads. In some embodiments, the plant loads may be related to the safety of the operation of the power plant. At least one of the plant loads may be a non-safety related load. In various embodiments, a PDM may be a DC power supply.

In at least one embodiment, the power plant may include one or more power-generating module (PGM) assemblies. At least one of the PGM assemblies may include a nuclear reactor. Accordingly, the power plant may be a modular nuclear power plant.

The operation of a power plant (and the included one or more PGM assemblies) requires powering various loads, such as but not limited to loads that drive motors, valve actuators, sensors, control rooms, control rods, radiation monitors, and other electrical and/or mechanical components. In some embodiments, electrical power is required to startup and/or operate a PGM assembly, but is not required to safely shutdown the operation of the PGM assembly. However, it may still be critical to provide DC power to the plant when the one or more PGM assemblies are not generating power. For instance, if DC power is momentarily lost to one or more of the plant loads, one or more safety-related system actuations may be triggered.

Because the PDMs are fault-tolerant, a loss of AC power from one or more of the PGM assemblies (or the power-distribution system) will not inadvertently trigger a safety-related system actuation. Furthermore, because the PDMs are fault-tolerant, the power-distribution system and PDMs may be maintained and/or replaced while the power plant is online and generating AC power for remote consumers. Accordingly, the PDMs enable a more flexible power plant maintenance schedule. In some embodiments, a fault tolerant system is a failure tolerant system.

In various embodiments, a PDM may be module-specific PDM. A module specific PDM corresponds to a specific PGM assembly included in the power plant. The module-specific PDM provides power to loads that are specific to the corresponding PGM assembly. In at least one embodiment, at least a portion of the power generated at the power plant and distributed to a particular module-specific PDM is generated by the corresponding PGM assembly, such that the operation of a PGM assembly is self-sustaining. Other PDMs may be common plant PDM. A common plant PDM may provide power to loads that are common to a plurality of PGM assemblies. The power generated at the power plant and distributed to a common plant PDM may be generated by one or more PGM assemblies.

In various embodiments, a module-specific PDM may include two redundant subdivisions: Subdivision I and Subdivision II. Furthermore, a module-specific PDM may include at least four power channels: Channel A, Channel B, Channel C, and Channel D, where Channel A and Channel C are included in Subdivision I and Channel B and Channel D are included in Subdivision II.

To enable fault-tolerance, in some embodiments, each power channel includes two batteries, two battery chargers, and one DC bus. At least one of the batteries may be a valve-regulated lead-acid (VRLA). Each power channel provides power to a corresponding load separation group. Thus, at least four load separation groups may be included: load separation group A, load separation group B, load separation group C, and load separation group D. Load separation group A and load separation group D are redundant, in that the plant loads grouped into each of group A and group D are identical, or at least similar.

In at least one embodiment, when under normal fault-free operating conditions, a portion of the power generated by the power plant is provided to a module-specific PDM as alternating current (AC) at an input voltage. The input voltage may be approximately <NUM> V AC. The module-specific PDM transforms the AC power into a DC current at an output voltage. In various embodiments, the DC output voltage may be less than the AC input voltage. In at least one embodiment, the output voltage is approximately <NUM> V DC. While supplying the output voltage to the various load separation groups, the module-specific PDM maintains the float voltage on the included batteries via the corresponding battery chargers.

In the event of loss of the AC input power to a module-specific PDM (a fault event), the batteries continue to provide the DC output power to each of the load separation groups for at least a predetermined amount of time. Each of the redundant batteries may provide the full load to each of the corresponding load separation groups.

In some embodiments, a common plant PDM includes at least two subdivisions: Subdivision I and Subdivision II. Each subdivision includes two redundant batteries, such as but not limited to VRLA batteries, two battery-charging modules, and at least one DC bus. Subdivision I and Subdivision II are redundant, in that the common plant loads corresponding to Subdivision I and Subdivision II are identical, or at least similar.

In at least one embodiment, when under normal fault-free operating conditions, a portion of the power generated by the power plant is provided to a common plant PDM as alternating current (AC) at an input voltage. The input voltage may be approximately <NUM> V AC. The common plant PDM transforms the AC power into a DC current at an output voltage. In various embodiments, the DC output voltage may be less than the AC input voltage. In at least one embodiment, the output voltage is approximately <NUM> V DC. While supplying the output voltage, the common plant PDM maintains the float voltage on the included batteries via the corresponding battery chargers.

In the event of loss of the AC input power to a common plant PDM, the batteries continue to provide the DC output power to loads in Subdivision I or Subdivision II for at least a predetermined amount of time. Each of the redundant batteries may provide the full load to each of the corresponding subdivision.

Both the module-specific and the common plant PDMs include sufficient redundancy for each component such that one or more components may be removed from service during normal power plant operation and without a loss of power plant function. Accordingly, maintenance may be performed without taking the plant offline from power generation capacity for remote consumers. PDMs may include switches to transfer loads between the redundant components. For instance, a particular PDM may transfer loads within a single channel within the particular PDM. The switches may be disposed between the batteries, the battery-charging modules, and the various DC buses.

<FIG> provides a schematic view of a power-generating module (PGM) assembly <NUM> that is consistent with the various embodiments disclosed herein. In some embodiments, PGM assembly <NUM> is a modular nuclear reactor assembly, although other embodiments are not so constrained and PGM assembly <NUM> may be any modular assembly that generates flowing energy (heat). In some embodiments, PGM assembly <NUM> is a modular fission reactor assembly. In at least one embodiment, PGM assembly <NUM> is a modular fusion reactor assembly.

PGM assembly <NUM> may be housed in a PGM bay <NUM>. The PGM bay <NUM> may include a cooling pool <NUM> of water or some other material that includes thermal properties enabling the cooling of PGM assembly <NUM>. At least a portion of the PGM assembly <NUM> may be submerged in the cooling pool <NUM>. Accordingly, at least a portion of the PGM assembly <NUM> may be below the top of a water line <NUM> of the cooling pool.

PGM assembly <NUM> includes PGM core <NUM>. PGM core <NUM> may be any device, assembly, apparatus, or configuration that is employed to controllably generate heat. Thus, PGM assembly <NUM> may be an embodiment of a heat generating assembly. In some embodiments, PGM core <NUM> may be a nuclear reactor core, such as but not limited to a fission reactor core. PGM core <NUM> may be immersed in PGM coolant <NUM>. In at least one embodiment, PGM coolant <NUM> includes water or any other material that enables the flow of heat (generated by the PGM core <NUM>) away from the PGM core <NUM>.

In some embodiments, PGM assembly <NUM> includes a core shroud <NUM> that at least partially constrains, channels, or otherwise guides a flow of PGM coolant <NUM>. As shown in <FIG>, PGM core <NUM> may be at least partially surrounded by the core shroud <NUM>. The PGM core <NUM>, the core shroud <NUM>, and the PGM coolant <NUM> are housed within a pressure vessel <NUM>.

In various embodiments, PGM core <NUM> generates heat that is transferred to the PGM coolant <NUM>. As shown by the flow arrows in <FIG>, heating the PGM coolant <NUM> in the pressure vessel <NUM> generates a generally vertical circular convection current of the PGM coolant <NUM>. The core shroud <NUM> at least partially constrains, channels, or otherwise guides the generally vertical circular convection current of the PGM coolant <NUM>. A pressurizer <NUM> may regulate the internal pressure within pressure vessel <NUM> that is due to at least the heating and/or the convection current of the PGM coolant <NUM>.

The PGM core <NUM> heats the portion of the PGM coolant <NUM> that is in the lower plenum <NUM> of the core shroud <NUM>. The heated PGM coolant <NUM> flows upward and out of the shroud riser <NUM>. As the PGM coolant <NUM> flows upward, the heated PGM coolant <NUM> provides heat to a plurality of steam generators <NUM>. Due to at least this heat exchange, as the heated PGM coolant <NUM> flows out of the shroud riser <NUM>, the PGM coolant <NUM> is cooled. As shown by the flow arrows in <FIG>, once outside of the shroud riser <NUM>, the PGM coolant <NUM> flows generally downward between the core shroud <NUM> and the pressure vessel <NUM>. The convection current pulls the cooled PGM coolant <NUM> near the lower plenum <NUM> back into the core shroud <NUM>. The PGM core <NUM> reheats the PGM coolant <NUM> such that the convection current continues to circulate and cool the PGM core <NUM>.

The pressure vessel <NUM> may be housed within a containment vessel <NUM>. The containment vessel <NUM> may insure the containment of material within the pressure vessel <NUM>, including any material included in the PGM core <NUM>, as well as the PGM coolant <NUM>. In some embodiments, the PGM assembly <NUM> includes a plurality of PGM vent valves <NUM> and/or a plurality of PGM recirculation valves <NUM> to vent pressure within and/or dissipate excess heat away from the pressure vessel <NUM>.

Feedwater may flow in a circuit that includes the steam generators <NUM> and electrical generators (not shown in <FIG>). Within the steam generators <NUM>, the feedwater is heated to generate stream. The generated steam flows out of the steam headers <NUM> and carries the transferred heat away from PGM assembly <NUM>. A plurality of steam isolation valves <NUM> regulate the flow of the steam away from the PGM assembly <NUM>. The steam may be routed via a steam bus, such as but not limited to steam bus <NUM> of <FIG>, to electrical generators, such as but not limited to turbine generator <NUM> of <FIG>, to generate electrical power or some other form of usable power.

After the energy within the steam generates the electrical power, the return of the cooled feedwater to the PGM assembly <NUM> may be regulated via a plurality of feedwater isolation valves <NUM>. The cooled feedwater is returned to the steam generators <NUM> via the feedwater headers <NUM>, to complete the circuit.

In at least some embodiments, even after a shutdown of the PGM assembly <NUM>, the PGM core <NUM> may continue to generate heat. For instance, in embodiments where the PGM core <NUM> includes a nuclear reactor core, the nuclear reactor core may continue to generate heat during a decay period associated with the spent fuel within the nuclear reactor core. The heat that is generated after a shutdown of the PGM assembly <NUM> may be decay heat. Accordingly, to ensure that the PGM core <NUM> and other components of the PGM assembly <NUM> do not overheat, at least due to decay heat, the power generated by the PGM core <NUM> may be dissipated.

To dissipate decay heat in some embodiments, the PGM assembly <NUM> includes a decay hear removal system (DHRS). The DHRS may include a plurality of DHRS heat exchangers <NUM> submerged in the cooling pool <NUM> of the PGM bay <NUM>, as well as a plurality of a plurality of DHRS valves <NUM> to divert the flow of the feedwater/steam away from the steam bus.

During a shutdown of the PGM assembly <NUM>, or during another event where it is desired to not provide the steam and/or heated feedwater to the electrical generators, the plurality of steam isolation valves <NUM> may be closed such that the steam and/or heated feedwater does not flow to the electrical generators. Rather, the steam and/or heated feedwater flows through the plurality of DHRS heat exchangers <NUM> and is cooled. The DHRS heat exchangers <NUM> dump the excess heat into cooling pool <NUM>. The circular flow of feedwater through the decay heat exchangers <NUM> may be regulated by the plurality of DHRS valves <NUM>.

The rate of power generation of the of the PGM core <NUM> may be regulated by the positioning of one or more control rods <NUM>. The positioning of the one or more control rods <NUM> may be driven by control rod drives <NUM>.

PGM assembly <NUM> includes a plurality of diagnostic sensors <NUM> schematically shown in <FIG>. Diagnostic sensors <NUM> may sense and/or generate sensor data to monitor various components of PGM module <NUM>. Diagnostic sensors <NUM> may include various types of sensors, such as but not limited to temperature sensors, pressure sensors, valve configuration sensors control rod positioning sensors, radioactivity sensors, fluid and gas flow sensors, or any other sensor that monitors parameters of the PGM assembly <NUM>. Diagnostic sensors <NUM> provide sensor output signals on a sensor data bus <NUM>. Sensor output data may be diagnostic sensor data, or simply sensor data. Diagnostic sensors <NUM> may include safety sensors or safety-related sensors, as well as asset protection-related sensors.

<FIG> provides a schematic view of a modular power plant <NUM> that is consistent with the various embodiments disclosed herein. Modular power plant <NUM> includes power-generating module (PGM) assembly array <NUM>. PGM assembly array <NUM> includes one or more PGM assemblies, such as but not limited to PGM assemblies <NUM>. In some embodiments, at least one of the PGM assemblies <NUM> included in PGM assembly array <NUM> may include similar features to PGM assembly <NUM> of <FIG>. As shown in <FIG>, in at least one embodiment, PGM assembly array <NUM> includes twelve PGM assemblies. However, in other embodiments, the number of PGM assemblies included in PGM assembly array <NUM> includes more or less than twelve PGM assemblies. A PGM housing <NUM> may house at least a portion of the PGM assembly array <NUM>.

In some embodiments, one or more generator housings <NUM> house a generator array <NUM>. Generator array <NUM> includes one or more devices that generate electrical power or some other form of usable power from steam generated by the PGM assembly array <NUM>. Accordingly, generator array <NUM> may include one or more electrical generators, such as but not limited to turbine generators <NUM>. As shown in <FIG>, in at least one embodiment, generator array <NUM> includes twelve electrical generators. However, in other embodiments, the number of electrical generators included in generator array <NUM> includes more or less than twelve electrical generators. In at least one embodiment, there is a one to one correspondence between each PGM assembly included PGM assembly array <NUM> and each electrical generator included in generator array <NUM>.

A steam bus <NUM> may route the steam generated by PGM assembly array <NUM> to the generator array <NUM>. The steam bus <NUM> may provide the one to one correspondence between the PGM assemblies included in the PGM assembly array <NUM> and the electrical generators included in the generator array <NUM>. For instance, the steam bus <NUM> may insure that the steam generated by a particular PGM assembly is provided only to a particular electrical generator. The steam bus <NUM> may additionally insure that the steam provided to the particular electrical generator is generated only by the particular PGM assembly.

A portion of the power generated by each of the generators in each of the generator arrays <NUM> may be transmitted to remote consumers. For instance, a portion of the generated power may be provided to a switchyard and fed into a power grid to be transmitted to remote consumers. This remotely transmitted power may provide electrical power to homes, businesses, and the like.

However, at least another portion of the generated power may be used locally within power plant <NUM> to at least partially operate power plant <NUM>. For instance, a portion of the generated electrical power may be distributed to various electrical loads within power plant <NUM>. The locally distributed power may be utilized for the operation of power plant <NUM>, such as, but not limited to, providing power to the control room <NUM> of power plant <NUM>.

In order to match the transmission voltages of the switchyard and a power grid, the portion of the power generated by each generator to be remotely transmitted is routed, via a power signal, to one or more remote voltage transmission transformers <NUM>. Because the transmission of electrical power may be more efficient at higher voltages, in some embodiments, the one or more remote transmission transformers <NUM> may be step-up transformers.

<FIG> shows the remotely transmitted power portion from each of the generators routed to remote transmission transformers <NUM>. After the voltage is transformed to a transmission voltage, the power to be remotely transmitted is routed, via a remote transmission bus <NUM> to a switchyard (not shown). Because remote transmission transformers <NUM> provide power for the end users of power plant <NUM>, transformers included in the remote transmission transformers <NUM> may be main power transformers (MPTs).

In order to provide local power at appropriate voltages within power plant <NUM>, the portion of the power generated by each generator to be locally distributed is routed, via a power signal, to one or more local distribution voltage transformers <NUM>. Because the various loads within power plant <NUM> may require voltages less than the voltage that is output by the generators, the one or more local distribution transformers <NUM> may be step-down transformers. The transformers included in the local distribution transformers <NUM> may be unit auxiliary transformers (UATs).

<FIG> shows the locally distributed portion of the power signal from each of the generators routed from the generators to local distribution transformers <NUM>. After the voltage of the power signal is transformed to one or more local distribution voltages, the power signal to be locally distributed is routed, via a local distribution bus <NUM>, to one or more power-distribution modules (PDM) <NUM>. The PDMs <NUM> provide power to the various loads within power plant <NUM>. The PDMs <NUM> may be fault-tolerant PDMs.

<FIG> provides a schematic view of a plurality of fault-tolerant PDM feeds for the PDMs <NUM> of <FIG> that are consistent with the various embodiments disclosed herein. A PDM feed (or simply a feed) may be an electrical coupling or connection that provides AC electrical power from the local distribution bus <NUM> to one or more corresponding PDMs. As such, although the PDMS are not shown in <FIG>, each of feeds shown in <FIG> provide power to a corresponding PDM that distributes the power to the power plant. At least a portion of the PDMs may be specific to or correspond to a generator included in the generator array <NUM> of power plant <NUM>. Various embodiments of PDMs are discussed throughout, including at least with respect to <FIG>.

As shown in <FIG>, there are twelve PDM feeds where each PDM feed provides power to a PDM that corresponds to one of the twelve generators included in generator arrays <NUM>. These twelve module-specific PDM feeds are labeled PDM_1-PDM_12. Furthermore, the plurality of PDMs feeds may include one or more common plant PDM feeds, such as the two common-plant PDMs (PDM_CP) shown in <FIG>.

An alternating current (AC) power signal is provided to each of the plurality of PDM feeds via local distribution bus <NUM>. In at least one embodiment, the AC power signal provided to each of the PDM feeds is generated by the corresponding PGM assembly/generator pair of power plant <NUM> of <FIG>. Each of the PDM feeds is enabled to receive power from the local distribution bus and provide the power to one or more corresponding PDMS. As discussed below, a PDM is enabled to employ the received AC power signal to provide a direct current (DC) power signal to supply electrical power to various plant loads.

In some embodiments, a module-specific PDM (such as those that are provided power via PDM feeds PDM_1-PDM_12) provides DC power to loads that are specific to the corresponding PGM assembly and generator pair that generated the power provided to the module-specific PDM. A common-plant PDM (such as those that are provided power via one of PDM feeds PDM_CP) may provide DC power to loads that are common to a plurality of PGM assemblies and to the power plant.

As discussed further below, each of the PDMs include batteries and corresponding battery chargers. The PDMs are enabled to store energy provided by the AC power signal such that in the event that a particular PGM, generator, or the power distribution system faults and/or shutdowns, each of the PDMs may continue to provide DC power, via the included batteries, to fully supply the required loads. For instance, each of the PDM feeds may include a plurality of redundant feeds, shown schematically as redundant feeds <NUM> and <NUM> for module-specific feed PDM_1 and redundant feeds <NUM> and <NUM> for common-plant feed PDM_CP.

Furthermore, each PDM is fault-tolerant in that faults within a specific PDM will not inhibit the PDM from providing the DC power signals at full capacity. As such, each PDM includes redundant channels, batteries, battery chargers, and the like. As discussed further below, a module-specific PDM, such as provided by feed PDM_1 includes two redundant subdivisions: Subdivision I and Subdivision II. As discussed below, each subdivision in module-specific may enabled to provide the DC power signals required to operate, shutdown, and monitor the corresponding PGM, for at least a predetermined amount of time. In some embodiments, electrical power is not required to safely shutdown a PGM. Each subdivision may provide the required DC power when AC power signal is delivered via local distribution bus <NUM>. Furthermore, each subdivision may provide the required DC power when the AC power signal is not delivered via local distribution bus <NUM>.

The module-specific PDM provided power by PDM_1 may tolerate a fault in one of Subdivision I or Subdivision II because the subdivisions are independent and/or redundant. As further discussed below, subdivisions within module-specific PDMs include multiple channels that further increase redundancy. Likewise, a common-plant PDM, such as the PDM provided power by one of PDM_CS includes two redundant subdivision: Subdivision I and Subdivision II.

<FIG> include one-line diagrams of power-distribution systems and modules. As such, structures, features, and components are shown in somewhat schematic representations. The various embodiments may include more (or less) components and features as shown in <FIG>. Accordingly, each switchgear module, cable bus module, and other structures shown in the various figures may include more or less components, such as switches, breakers, busses, connections, fuses, and input/output terminals. Only single conducting (or power transmission) paths are represented. However, several conducting paths, input/output terminals, and the like may be present in the various embodiments. An input terminal, output terminal, or other sort of connection may be shown to schematically represent multiple inputs, outputs, or other connections. Busses or transmission paths may be shown as a single line but include several separate and distinct transmission paths to transmit separate power signals from separate sources to separate destinations. The various power signals may be multi-phase signals, such as three-phase signals. One-line diagrams are used throughout for simplicity and clarity in presentation.

<FIG> shows a one-line schematic diagram for a first portion <NUM> of a fault-tolerant power distribution system that distributes locally generated power for the operation of a power plant that includes twelve modular generators. <FIG> shows a one-line schematic diagram for a second portion <NUM> of a fault-tolerant power distribution system that distributes locally generated power for the operation of a power plant that includes twelve modular generators.

In <FIG> and <FIG>, some of the details regarding switchgear are shown only schematically. Accordingly, more or less switches, breakers, and other components may be included. Portion <NUM> of the system (<FIG>) may be directed towards the upper six PM assemblies and upper six generators of power plant <NUM> of <FIG>. Portion <NUM> of the system (<FIG>) may be directed towards the lower six PM assemblies and lower six generators of power plant <NUM>. The system is a fault tolerant system with redundant power transmission paths, PDMs main power transformers (MPTs), and unit auxiliary transformers (UATs).

Portion <NUM> includes six generators: GEN_1, GEN_2, GEN_3, GEN_4, GEN_5, and GEN_6. Each of the six generators is selectively coupled to at least two of four front-end switchgear modules (SGM): SGM_0_1, SGM_0_2, SGM_0_3, and SGM_4. A separate main power transformer (MPT) is selectively coupled to one of the four front-end switchgear modules to redundantly provide power to the switchyard. Portion <NUM> also includes a corresponding backend switchgear module for each of the four front-end modules: SGM_1_1, SGM_1_2, SGM_1_3, and SGM_1_4. Each front-end switchgear module is coupled to the corresponding backend switchgear module via cable bus modules and a corresponding unit auxiliary transformer: UAT_1, UAT_2, UAT_3, and UAT_4. As shown in <FIG>, a voltage regulating transformer <NUM> may be used in combination with one or more of the UATs.

Portion <NUM> also includes a power-distribution module for each of the six generators. The power-distribution modules are not shown in <FIG>. Each of the six power-distribution modules includes at least two redundant power-distribution modules feeds. Each of power-distribution module feeds PDM_1_0 and PDM_1_1 provides power to the power-distribution module that corresponds to GEN_1. Each of power-distribution module feeds PDM_2_0 and PDM_2_1 provides power to the power-distribution module that corresponds to GEN_2. Each of power-distribution module feeds PDM_3_0 and PDM_3_1 provides power to the power-distribution module that corresponds to GEN_3. Each of power-distribution module feeds PDM_4_0 and PDM_4_1 provides power to the power-distribution module that corresponds to GEN_4. Each of power-distribution module feeds PDM_5_0 and PDM_5_1 provides power to the power-distribution module that corresponds to GEN_5. Each of power-distribution module feeds PDM_6_0 and PDM_6_1 provides power to the power-distribution module that corresponds to GEN_6.

Various embodiments of a power-distribution module feed (for instance PDM_1_0) includes four sub-feeds. As described below, various embodiments of power-distribution modules include four separate channels (Channel A, Channel B, Channel C, and Channel D). Such embodiments include power-distribution module <NUM> of <FIG>. PDM_1_0 feeds into two of the four channels (for instance Channel A and Channel C) of the corresponding power-distribution module. Two of the sub-feeds of PDM_1_0 feed into one of the two channels (for instance Channel A) and the other two sub-feeds of PDM_1_0 feed into the other channel of the two channels (for instance Channel C). Similarly, PDM_1_1 feeds into the other two of the four channels (for instance Channel B and Channel D) of the corresponding power-distribution module. Two of the sub-feeds of PDM_1_1 feed into one of the two channels (for instance Channel B) and the other two sub-feeds of PDM_1_1 feed into the other channel of the two channels (for instance Channel D). Accordingly, various embodiments of power-distribution module, such as but not limited to PDM <NUM> of <FIG>, receive power from up to <NUM> separate sub-feeds (four separate sub-feeds in each of two power-distribution feeds). As shown in at least <FIG>, each of the four sub-feeds within a power-distribution module feed feeds into a separate charging module included in the corresponding power-distribution module.

Each of these redundant power-distribution module feeds is coupled to the outputs of one of four backend switchgear modules: SGM_1_1, SGM_1_2, SGM_1_3, and SGM_1_4. The system shown in <FIG> is a fault tolerant system with redundant power transmission paths, power-distribution module feeds, main power transformers (MPTs), and unit auxiliary transformers (UATs) for each of the generators.

In various embodiments, the system may include one or more backup generators (GEN_B). In at least one embodiment, the voltage output of GEN_B is approximately <NUM> kVAC. GEN_B may be coupled to feed <NUM> through one or more switches. GEN_B may also be coupled to one or more of the front-end switchgear modules: SGM_0_1, SGM_0_2, SGM_0_3, SGM_0_4, SGM_0_5, and SGM_0_6 through one or more switches. GEN_B may be employed to provide power to the power plant in the event that one or more of the PGM assemblies and/or corresponding generators is unavailable for power generation. A first feed <NUM> corresponding to GEN_B may be selectively coupled to at least one of the front-end modules, such as but not limited to SGM_0_1. A second feed <NUM> corresponding to GEN_B may be selectively coupled to one of the backend modules, such as but not limited to SGM _1_1. In some embodiments, one or more other backup generators (not shown in <FIG>) may be configured provide an AC signal to the one or more of the PDMS at a lower voltage than the AC signals generated by GEN_B. For instance, GEN_B may generate a <NUM> kV AC signal, while the one or more generators that provide power to the PDMs may generate a <NUM> V AC signal.

The system may include additional power-distribution module feeds coupled to one or more of the backend switchgear modules. For instance, power-distribution module feeds <NUM>, <NUM>, <NUM>, and <NUM> may provide power to other power-distribution modules that distribute power to loads that are common to each of the six generators included in system portion <NUM>. The power-distribution modules that are provided power by power-distribution module feeds <NUM>, <NUM>, <NUM>, and <NUM> may be common-plant PDMs. Accordingly, feeds <NUM>, <NUM>, <NUM>, and <NUM> may be common-plant feeds. Power-distribution module feeds <NUM>, <NUM>, <NUM>, and <NUM> may provide power to power-distribution modules for various common pumps and motors included in the power plant.

As described below, various examples of power-distribution modules include two separate subdivisions (Subdivision I and Subdivision II). Such examples include power-distribution module <NUM> of <FIG>. A common-plant feed, such as but not limited to feeds <NUM>, <NUM>, <NUM>, and <NUM> feeds into each of the subdivisions of the corresponding common plant power-distribution modules. Two of the sub-feeds of common-plant feed <NUM> feed into one of the two subdivisions (for instance Subdivision I) and the other two sub-feeds of common-plant feed <NUM> feed into the other subdivision (for instance Subdivision II). Accordingly, various embodiments of power-distribution modules, such as but not limited to PDM <NUM> of <FIG>, receive power from up to four separate sub-feeds included in a common-plant power distribution feed. As shown in at least <FIG>, each of the four sub-feeds within a common-plant power-distribution module feed feeds into a separate charging module included in the corresponding common-plant power-distribution module.

Each of the various power-distribution modules may distribute power in real time. Furthermore, as discussed in the context of <FIG>, one or more of the power-distribution modules may include one or more charging modules to charge one or more batteries that store power for later use. Feed <NUM> corresponds to GEN_B may be coupled to one or more of the front-end switchgear modules. Feed <NUM> may be coupled to one or more of the backend switchgear module.

System portion <NUM> of <FIG> includes similar features to system portion <NUM> of <FIG>. For instance, system portion <NUM> includes six generators: GEN_7, GEN_8, GEN_8, GEN_10, GEN_11, and GEN_12. Each of the six generators is selectively coupled to at least two of four front-end switchgear modules: SGM_0_5, SGM_0_6, SGM_0_7, and SGM_8. A separate main power transformer (MPT) is selectively coupled to one of the four front-end switchgear modules to redundantly provide power to the switchyard. Portion <NUM> also includes a corresponding backend switchgear module for each of the four front-end modules: SGM_1_5, SGM_1_6, SGM_1_7, and SGM_1_8. Each front-end switchgear module is coupled to the corresponding backend switchgear module via a corresponding unit auxiliary transformer: UAT_5, UAT_6, UAT_7, and UAT_8. As shown in <FIG>, a voltage regulating transformer <NUM> may be used in combination with one or more of the UATs.

Portion <NUM> also includes a power-distribution module (not shown) for each of the six generators. Each of the six power-distribution modules includes at least two redundant power-distribution modules feeds. Each of power-distribution module feeds PDM_7_0 and PDM_7_1 provides power to the power-distribution module that corresponds to GEN_7. Each of power-distribution module feeds PDM_8_0 and PDM_8_1 provides power to the power-distribution module that corresponds to GEN_8. Each of power-distribution module feeds PDM_9_0 and PDM_9_1 provides power to the power-distribution module that corresponds to GEN_9. Each of power-distribution module feeds PDM_10_0 and PDM_10_1 provides power to the power-distribution module that corresponds to GEN_10. Each of PDM_11_0 and PDM_11_1 correspond to GEN_11. Each of power-distribution module feeds PDM_12_0 and PDM_12_1 provides power to the power-distribution module that corresponds to GEN_12. Each of these redundant power-distribution module feeds is coupled to the outputs of one of four backend switchgear modules. As discussed above in the context of <FIG>, various embodiments of power-distribution module feeds include four sub-feeds. Common-plant power-distribution module feeds are also shown in portion <NUM>.

<FIG> shows a schematic view of an embodiment of a fault-tolerant module-specific PDM <NUM>. Module-specific PDM <NUM> provides a DC power signal to a plurality of module-specific plant loads associated with and/or assigned to module-specific PDM <NUM>. Module-specific PDM <NUM> includes two subdivisions: Subdivision I and Subdivision II. Subdivision I includes two power channels: Channel A and Channel C. Subdivision II also includes two channels: Channel B and Channel D.

As discussed further below, each of the power channels may include at least two redundant batteries, at least two redundant battery charging modules, and a DC bus. Each of the four channels provides power to a corresponding load separation group (LSG). For example, Channel A serves the corresponding LSG A. Module-specific loads associated with and/or assigned to Channels A and D are equivalent. Likewise, module-specific loads associated with and/or assigned to Channels B and C are equivalent.

Under normal power plant operations, such as when the corresponding PGM is generating power, the module-specific PDM <NUM> receives an AC power signal that is generated from within the power plant. Module-specific PDM <NUM> outputs a DC power signal that includes energy from the received AC power signal. The voltage of the AC power signal may be greater than the voltage of the outputted DC power signal. For instance, the voltage of the inputted AC power signal may be approximately <NUM> V AC. The voltage of the outputted DC signal may be approximately <NUM> V DC. Module-specific PDM <NUM> provides the outputted DC power signal to the associated and/or assigned plant loads, while charging and/or maintaining the float voltage on the redundant batteries.

In the event that the AC power signal is not being received (such as when the operation of the PGM that generated the AC signal is shutdown), at least one of the batteries included in the module-specific PDM <NUM> outputs that DC power signal. The batteries may be enabled with sufficient capacity to supply the assigned plant loads for a predefined duty cycles, such as <NUM> or <NUM> hours. Each of the two redundant batteries included in a power channel may be enabled to carry the full load assigned to the power channel. In some embodiments, both batteries included in a channel may be enabled to fully supply the load for at least <NUM> hours. In other channels, both batteries may be enabled to fully supply the load for at least <NUM> hours. For instance, both batteries in each of Channel A and Channel D may be enabled to fully supply the load for at least <NUM> hours. Similarly, both batteries in each of Channel B and Channel C may be enabled to fully supply the load for at least <NUM> hours.

As described below, module-specific PDM <NUM> includes such redundancy that any component included in module-specific PDM <NUM> may be removed from service (such as for maintenance operations), or experience a fault-condition without loss of functionality of module-specific PDM <NUM>.

More specifically, each channel provides power to a load separation group: Load Separation Group A, Load Separation Group B, Load Separation Group C, and Load Separation Group D for the respective channels. As discussed further below, the loads assigned to Load Separation Group A and D are identical. Additionally, each load separation group includes a complete, independent set of equipment that requires power. Accordingly, Channels A and D are redundant channels. Similarly, Channels B and C are redundant channels because the loads assigned to Load Separation Group B and D are identical.

For instance, Channel A may provide power to a portion of the Instrumentation and Control (I&C) loads associated with the power plant, such as loads associated with I&C separation group A. Channel A may additionally provide power to a portion of the I&C loads associated with Subdivision I (I&C Subdivision I loads). Similarly, Channel C may provide power to loads associated with I&C separation group C. Furthermore, because Subdivision I is a redundant subdivision, Channel C may also provide power to at least a portion of the I&C Subdivision I loads.

One or more AC power signals are provided to module-specific PDM <NUM> via one or more AC busses, which may include one or more AC power busses. For instance, as shown in <FIG>, each of AC_BUS_A1 and AC_BUS_A2 provides power to Channel A. Each of AC_BUS_C1 and AC_BUS_C2 provides power to Channel C. Each of AC_BUS_B1 and AC_BUS_B2 provides power to Channel B. Each of AC_BUS_D1 and AC_BUS_D2 provides power to Channel D. Local distribution bus <NUM> of <FIG> may include one or more of the AC_BUS_A1, AC_BUS_A2, AC_BUS_C1, AC_BUS_C2, AC_BUS_B1, AC_BUS_B2, AC_BUS_D1, or AC_BUS_D2 as shown in <FIG>. The AC power signals may be generated in the power plant, such as by the PGM assembly and generator pair that is specific and/or associated with PDM <NUM>. Thus, PDM <NUM> includes a plurality of AC inputs from a plurality of AC busses of the power plant that provide an AC signal to the module. The AC inputs are enabled to receive an AC power signal.

Each of the AC busses may be selectively coupled to each of the four corresponding channels. Thus, the AC power signals carried by AC_BUS_A1/AC_BUS_A2 may be selectively provided to Channel A and the AC power signals carried by AC_BUS_B1/AC_BUS_B1 may be provided to Channel B. The AC power signals carried by AC_BUS_C1/AC_BUS_C2 may be provided to Channel C and the AC power signals carried by AC_BUS_D1/AC_BUS_D2 may be provided to Channel D. Switches between a channel AC bus and the corresponding channel may be employed to couple and decouple the channel AC bus to the corresponding channel to selectively provide the AC power signal to the corresponding channel. As shown in <FIG>, in some embodiments, these switches are outside of PDM <NUM>. In other embodiments, these switches may be included in PDM <NUM>.

As shown in <FIG>, AC_BUS_A1 provides AC power to the charging module <NUM> of Channel A and AC_BUS_A2 provides AC power to charging module <NUM> of Channel A. AC_BUS_C1 provides AC power to the charging module <NUM> of Channel C and AC_BUS_C2 provides AC power to charging module <NUM> of Channel C. AC_BUS_B1 provides AC power to the charging module <NUM> of Channel B and AC_BUS_B2 provides AC power to charging module <NUM> of Channel B. AC_BUS_D1 provides AC power to the charging module <NUM> of Channel D and AC_BUS_D2 provides AC power to charging module <NUM> of Channel D. Channels A and C may be included in Subdivision I. Channels B and C may be included in Subdivision II.

Module-specific PDM <NUM> includes one or more DC busses for each of the channels. As described herein, each of the four channels may selectively provide a DC power signal via the corresponding DC bus. A DC power bus may provide the DC signal to the various plant loads associated with and/or assigned to module-specific PDM <NUM>. A DC bus for a channel may provide the DC signal to a Load Separation Group (LSG) corresponding to the channel. For instance, Channel A DC Bus may provide a DC power signal from Channel A to LSG A, which corresponds to Channel A. Likewise, Channel C DC Bus may provide a DC power signal from Channel C to LSG C. Channel B DC Bus may provide a DC power signal from Channel B to LSG B. Similarly, Channel D DC Bus may provide a DC power signal from Channel D to LSG D.

The first subset of the plurality of module-specific plant loads associated with and/or assigned to Channels A and D may be associated with and/or assigned to LSGs A and D. Similarly, the second subset of the plurality of module-specific plant loads associated with and/or assigned to Channels B and C may be associated with and/or assigned to LSG B and C. As such, LSG A provides the DC power signal to the loads associated with Channel A, LSG B provides the DC power signal to the loads associated with Channel B, LSG C provides the DC power signal to the loads associated with Channel C, and LSG D provides the DC power signal to the loads associated with Channel D.

In various embodiments, each of the four channels includes at least two redundant batteries, which are shown as Battery <NUM> and Battery <NUM> in each of Channels A, B, C, and D. In some embodiments, at least one of the batteries may be a valve-regulated lead-acid (VRLA) battery. Furthermore, each channel includes two charging modules: Charging Module <NUM> and Charging Module <NUM>. Charging Module <NUM> may charge each of Battery <NUM> and Battery <NUM>, as well as maintain a battery float voltage on each of Battery <NUM> and Battery <NUM>. Likewise, Charging Module <NUM> may charge each of Battery <NUM> and Battery <NUM>, as well as maintain a battery flow voltage on each of Battery <NUM> and Battery <NUM>.

As shown in <FIG>, switches between a channel AC bus and the corresponding channel selectively couple and decouple the channel AC bus to the corresponding redundant battery/charging module pairs included in the corresponding channel. Accordingly, an AC power signal from a channel AC bus may be selectively provided to either one or both of the battery/charging module pairs included in the corresponding channel. As shown in <FIG>, in some embodiments separate and/or independent AC busses (or motor control centers) may be employed to provide AC power to each of the battery/charging module pairs.

Also shown in <FIG>, an AC power signal may be selectively provided to at least one of the charging modules included in a channel. Each of the charging modules include one or more rectifiers that rectify the provided AC power signal and output a DC power signal that includes a rectified portion of the AC power signal. In various embodiments, the one or more rectifiers may include one or more rectifier bridges.

The voltage of the inputted AC signal may be different from the voltage of the outputted DC power signal. One or more of the charging modules may include one or more transformers to transform the voltage of at least the inputted AC power signal. In at least one of the embodiments, at least one of the charging modules includes one or more DC-to-DC converters to convert the voltage of the outputted DC power signal. In at least one embodiment, the voltage of the inputted AC power signal is approximately <NUM> V AC. The voltage of the outputted DC power signal may be approximately <NUM> V DC.

Each of the charging modules may selectively provide at least a portion of the outputted DC power signal to a DC bus external to PDM <NUM> via the corresponding LSG. The corresponding LSG provides the DC power signal to the subset of the plurality of loads assigned to the LSG. The switches between a DC bus and each of the corresponding charging modules may be employed to couple and decouple the DC bus to each of the corresponding charging modules to selectively provide the DC power signal to the corresponding LSG.

At least another portion of the outputted DC power signal from a charging module may be selectively provided to the corresponding battery to charge and/or maintain the battery float voltage on the corresponding battery. As shown, switches between the charging module and the corresponding battery may be used to selectively couple and decouple the charging module to the battery. In at least one embodiment, the voltage of the DC power signal provided to the battery may be greater than the voltage of the DC power signal provided to the DC bus to charge and maintain the float voltage on the battery. Thus, separate DC-to-DC converters may be employed in the charging module to generate DC power signals with different voltages.

When the channel AC bus provides the AC power signal to the corresponding channel, such as when the corresponding PGM assembly and generator pair is generating the received AC power signal, at least one of the rectifiers included in the channel provides the DC signal to the LSG that corresponds to the channel. When the AC bus does not provide the AC power signal to the channel, such as when the corresponding PGM assembly and generator pair is shutdown, at least one of the batteries included in the channel provides the DC signal to the LSG that corresponds to the channel. The switches between the batteries and corresponding LSG may be used to selectively couple and decouple the batteries from the corresponding LSG.

Because the first subset of plurality of plant loads are assigned to both Channels A and D, Channels A and D are redundant channels. Likewise, Channels B and C are redundant channels. Because Channels A and C are included in Subdivision I and Channels B and D are included in Subdivision II, Subdivisions I and II are redundant subdivisions. Accordingly, module-specific PDM <NUM> is a fault-tolerant PDM.

Also, note that each channel includes redundant batteries and redundant charging modules. Accordingly, each channel is a redundant channel. In at least one embodiment, both batteries included in a channel may be enabled to fully supply the load for at least <NUM> hours. In other channels, both batteries may be enabled to fully supply the load for at least <NUM> hours. For instance, both batteries in each of Channel A and Channel D may be enabled to fully supply the load for at least <NUM> hours. Similarly, both batteries in each of Channel B and Channel C may be enabled to fully supply the load for at least <NUM> hours. The voltage of the DC power signal provided, via a battery, to the DC bus may be equivalent to the voltage of the DC power signal provided, via the charging modules, to the DC bus. Thus, each of the batteries may be approximately <NUM> V DC batteries.

As discussed throughout, each of the four channels includes two redundant charging battery/charging module pair. A first battery/charging module pair includes Battery <NUM> and Charging Module <NUM>. A second battery/charging module pair includes Battery <NUM> and Charging Module <NUM>. For a particular channel to provide the DC power signal to the DC bus, only one of the battery or the charging module of one of the two battery/charging module pairs of the channel is required as operative. Thus components may be removed (for maintenance), while the other string in the channel remain operative. Also, since Channel A and Channel D are redundant channels, only one of the four redundant battery/charging module pairs included in Channels A and D needs operative for module-specific PDM <NUM> to remain operational. Likewise, since Channel B and Channel C are redundant channels, only one of the four redundant battery/charging module pairs included in Channels B and C needs operative for module-specific PDM <NUM> to remain operational. Each of the redundant battery/charging pairs may be a separate and/or independent sub-system.

<FIG> shows a one-line schematic diagram for Channel A <NUM> of the module-specific PDM <NUM> of <FIG>. Channels B, C, and D of PDM <NUM> may include similar features and/or structures. Channel A <NUM> includes two redundant battery/charging module pairs. The first pair includes Charging Module <NUM>, Fused Transfer Switch Module <NUM>, Battery <NUM>, and Battery Monitor <NUM>. The second pair includes Charging Module <NUM>, Fused Transfer Switch Module <NUM>, Battery <NUM>, and Battery Monitor <NUM>.

The AC bus selectively provides the AC power signal to each of the charging modules in the first and the second battery/charging module pairs. A power signal is provided by the channel AC bus (AC_BUS_A1 and SC_BUS_A2). The voltage of the provided AC power signal may be approximately <NUM> V AC. Switches <NUM> may selectively couple AC_BUS_A1 to the Charging Module <NUM> and AC_BUS_A2 to Charging Module <NUM>. As shown in <FIG>, in some embodiments, switches <NUM> may be outside of the PDM that includes Channel A <NUM>. In other embodiments, switches <NUM> may be included in the PDM.

As shown in <FIG>, a fused transfer switch module may selectively couple and decouple each of the corresponding batteries to the DC bus included in the switchgear module. A fused transfer switch module may include a changeover switch <NUM>, one or more fuses <NUM>, and a battery test terminal. Changeover switch <NUM> may be a double pole changeover switch (DPCO).

The charging modules include one or more circuit breakers to provide protection from an over-voltage, under-voltage, or over-current event. For instance, charging modules may include AC supply breaker <NUM> and DC output breakers <NUM>. The charging modules may also include one or more rectifiers <NUM> to rectify the provided AC power signal. Rectifier <NUM> may include one or more transformers or DC-to-DC converters to output a DC power signal at a voltage that is approximately <NUM> V DC, or at least less than the voltage of the inputted DC signal.

In various embodiments, the charging modules include an indicator that indicates at least one charger output current, voltage, alarms for open DC output circuit breaker, DC output failure, AC supply failure, low and high DC output voltage, charger overload, and ground detection. The charging modules may include relays for high DC voltage shutdown events. Other components included in the charging modules may include transformers, DC-to-DC converters, relays, and other components discussed throughout.

Each redundant battery/charging module pair may also include a separate battery monitor. A battery monitor may include one or more indicators that indicate a battery current and/or voltage. A battery monitor may also include one or more alarms for battery overvoltage, under-voltage, and high or low room temperature. In some embodiments, each of the batteries may include multiple battery cells. For instance, a battery may include at least <NUM> cells.

In various embodiments, a communication link may be included between the redundant charging modules in each of the channels: A, B, C, and D. A communication link between charging modules may enable the two charging modules to share providing DC power to a single DC bus. Accordingly, in the various embodiments, multiple charging modules are enabled to share in the supplying DC power to the various DC bus loads. For instance, in <FIG>, communication link <NUM> is included between Charging Module <NUM> and Charging Module <NUM> for Channel A. Communication link <NUM> may include load-sharing circuity to enable Charging Module <NUM> and Charging Module <NUM> to share providing DC power to the DC bus for Channel A. It should also be noted that Charging Module <NUM> of Channel A is enabled to charge Battery <NUM> while simultaneously providing DC power to the DC bus for Channel A. Furthermore, Charging Module <NUM> of Channel A is enabled to charge Battery <NUM> while simultaneously providing DC power to the DC bus for Channel A.

At least a portion of the DC bus for Channel A <NUM> may be included in a switchgear module. The switchgear module may provide the DC signal to a LSG, such as LSG A in <FIG>. As shown, a plurality of switches <NUM> may selectively couple the charging modules and the batteries (via fused transfer switch modules) to the DC bus.

The switchgear module may include another plurality of switches, such as switch <NUM> that selectively couples the DC bus to each of the DC loads associated with and/or assigned to LSG A. Switchgear module may include a plurality of fuses, such as fuse <NUM>, to protect the various DC loads from an over current event. In various embodiments, at least one of the plurality of switches included in the switchgear module may be a double-pole single-throw (DPST) switch. The switchgear module may also include one or more alarms to indicate a change of a switch or breaker status.

The plurality of DC loads may include, but are not otherwise limited to radiation monitors, sensors, motors, actuators, valves, loads associated with the control room, or any loads required to start, operate, and shutdown a PGM assembly, such PGM assembly <NUM> of <FIG>.

In accordance with the invention as claimed herein, a PDM is a module-specific PDM. In an alternative case, not part of the claimed invention but which where discussed below may clarify features of the invention, a PDM may be a common plant PDM.

<FIG> shows a schematic view of an example of a fault-tolerant common plant power-distribution module. Common plant PDM <NUM> provides a DC power signal to a plurality of loads that are common to a plurality of PGM and associated with and/or assigned to common plant PDM <NUM>. Various examples of common plant PDM <NUM> may include similar features and/or structures to module-specific PDM <NUM> of <FIG>. For instance, similar to module-specific PDM <NUM>, common plant PDM <NUM> includes two subdivisions: Subdivision I and Subdivision II. Subdivision I and Subdivision II of common plant PDM <NUM> may be equivalent and/or redundant subdivisions.

As discussed further below, each of the subdivisions may include at least two redundant batteries, at least two redundant battery charging modules, and a DC bus. Each of the common plant loads associated with and/or assigned to common plant PDM <NUM> are served by exactly one of Subdivision I or Subdivision II. Thus, Subdivision I and Subdivision II are redundant subdivisions of common plant PDM <NUM>.

Under normal power plant operations, such as when at least one of the PGMs is generating power, the common plant PDM <NUM> receives an AC power signal that is generated from within the power plant. Common plant PDM <NUM> outputs a DC power signal that includes energy from the received AC power signal. The voltage of the AC power signal may be greater than the voltage of the outputted DC power signal. For instance, the voltage of the inputted AC power signal may be approximately <NUM> V AC. The voltage of the outputted DC signal may be approximately <NUM> V DC. Common plant PDM <NUM> provides the outputted DC power signal to the associated and/or assigned common plant loads, while charging and/or maintaining the float voltage on the redundant batteries.

In the event that the AC power signal is not being received (such as when the operation of the PGM that generated the AC signal is shutdown), at least one of the batteries included in the common plant PDM <NUM> outputs that DC power signal. The batteries may be enabled with sufficient capacity to supply the assigned plant loads for a predefined duty cycles, such as <NUM> or <NUM> hours. Each of the two redundant batteries included in each subdivision may be enabled to carry the full load assigned to common plant PDM <NUM>. In some embodiments, the first battery included in a subdivision may be enabled to fully supply the load for at least <NUM> hours and the second battery may be enabled to fully supply the load for at least <NUM> hours.

As described below, common plant PDM <NUM> includes such redundancy that any component included in common PDM <NUM> may be removed from service (such as for maintenance operations), or experience a fault-condition without loss of functionality of common plant PDM <NUM>.

More specifically, one or more AC power signals are provided to common plant PDM <NUM> via one or more AC busses, which may include one or more AC power busses. In the embodiment shown in <FIG>, Subdivision I AC Bus may provide Subdivision I one or more AC power signals to Subdivision I of PDM <NUM>. Similarly, Subdivision II AC Bus provides one or more AC power signals to Subdivision II of PDM <NUM>. Local distribution bus <NUM> of <FIG> may include Subdivision I AC Bus and Subdivision II AC Bus, as shown in <FIG>. The AC power signals may be generated in the power plant, such as by one or more PGM assembly and generator pairs. Thus, PDM <NUM> includes a plurality of AC inputs. A local distribution bus of the power plant provides one or more AC signals to the plurality of AC inputs.

Accordingly, each of Subdivision I AC Bus_1 and Subdivision AC Bus_2 may be selectively coupled to corresponding Subdivision I of PDM <NUM>. Each of Subdivision II AC Bus_1 and Subdivision II AC_Bus_2 may be selectively coupled to corresponding Subdivision II of PDM <NUM>. Thus, the AC power signals may be selectively provided to each of the corresponding subdivisions via the couplings. Switches between each of the subdivision AC busses and the corresponding subdivisions may be employed to couple and decouple the AC bus to the corresponding subdivision to selectively provide the AC power signal to the corresponding subdivision.

Common plant PDM <NUM> includes one or more DC busses corresponding to each of the two subdivisions. The plurality of DC busses may include one or more DC power busses. As described herein, each of the subdivisions may selectively provide a DC power signal to one or more corresponding DC busses. As shown in <FIG>, Subdivision I provides a DC power signal to corresponding Subdivision I DC Bus. Likewise, Subdivision II provides a DC power signal to corresponding Subdivision II DC Bus. The DC power busses may provide the DC signals to the various plant loads associated with and/or assigned to common plant PDM <NUM>. Each of Subdivision I DC Bus and Subdivision II DC Bus may be enabled to independently supply the corresponding DC power signal to each of the corresponding common plant loads associated with common plant PDM <NUM>. For instance, Subdivision I DC Bus supplies DC power to each of the Subdivision I loads and Subdivision II DC Bus supplies DC power to each of the Subdivision II loads.

In various embodiments, each of the subdivisions includes at least two redundant batteries, which are shown as Battery <NUM> and Battery <NUM> in each of Subdivision I and Subdivision II. In some embodiments, at least one of the batteries may be a valve-regulated lead-acid (VRLA) battery. Furthermore, each subdivision includes two charging modules: Charging Module <NUM> and Charging Module <NUM>. Charging Module <NUM> may charge Battery <NUM> and maintain a battery float voltage on Battery <NUM>. Likewise, Charging Module <NUM> may charge Battery <NUM> and maintain a battery flow voltage on Battery <NUM>.

As shown in <FIG>, switches between the AC bus and each of the subdivision selectively couple and decouple the AC busses to each of the corresponding redundant battery/charging module pairs included in the corresponding subdivision. Accordingly, an AC power signal may be selectively provided to either one or both of the battery/charging module pairs in each of the two subdivisions.

Also shown in <FIG>, the AC power signal may be selectively provided to at least one of the charging modules included in a subdivision. Each of the charging modules include one or more rectifiers that rectify the provided AC power signal and output a DC power signal that includes a rectified portion of the AC power signal. In various embodiments, the one or more rectifiers may include one or more rectifier bridges.

Each of the charging modules may selectively provide at least a portion of the outputted DC power signal to the corresponding subdivisions DC loads via the corresponding subdivision DC bus. As shown in <FIG>, Subdivision I DC Bus provides a DC signal from Subdivision I to Subdivision I DC Loads. Similarly, Subdivision II DC Bus provides a DC signal from Subdivision II to Subdivision II DC Loads. Thus, the corresponding subdivision DC bus provides the DC power signal to the plurality of loads assigned to the common plant PDM <NUM>. The switches between the DC busses and each of the charging modules may be employed to couple and decouple the subdivision DC bus to each of the charging modules or each of the batteries (included in the corresponding subdivision) to selectively provide the DC power signal to the corresponding subdivision DC bus.

At least another portion of the outputted DC power signal may be selectively provided to the corresponding battery to charge and/or maintain the battery float voltage on the corresponding battery. As shown, switches between the charging module and the corresponding battery may be used to selectively couple and decouple the charging module to the battery. In at least one embodiment, the voltage of the DC power signal provided to the battery may be greater than the voltage of the DC power signal provided to the DC bus to charge and maintain the float voltage on the battery. Thus, separate DC-to-DC converters may be employed in the charging module to generate DC power signals with different voltages.

When the AC bus provides the AC power signal to the corresponding subdivision, such as when a PGM assembly and generator pair is generating the received AC power signal, at least one of the rectifiers included in a subdivision provides the DC signal to the subdivision DC bus that corresponds to the subdivision. When the AC bus does not provide the AC power signal to the channel, such as when a PGM assembly is shutdown, at least one of the batteries included in the subdivision provides the DC signal to the subdivision DC bus that corresponds to the subdivision. The switches between the batteries and corresponding subdivision DC bus may be used to selectively couple and decouple the batteries from the corresponding subdivision DC bus.

Because each of Subdivision I is enabled to provide a DC power signal to each of the Subdivision I DC Loads and Subdivision II is enabled to provide a DC power signal to each of Subdivision II DC Loads, Subdivision I and Subdivision II are redundant subdivisions. Accordingly, common plant PDM <NUM> is a fault-tolerant PDM. Also, note that each subdivision includes redundant batteries and redundant charging modules. In at least one embodiment, the first battery in each subdivision is enabled to provide the DC power signal, at full capacity, to the corresponding subdivision DC bus for at least <NUM> hours. In some embodiments, the second battery in each channel is enabled to provide the DC power signal, at full capacity, to the corresponding subdivision DC bus for at least <NUM> hours. The voltage of the DC power signal provided, via a battery, to the DC bus may be equivalent to the voltage of the DC power signal provided, via the charging modules, to the DC bus. Thus, each of the batteries may be approximately <NUM> V DC batteries.

As discussed throughout, each of the subdivisions includes two redundant battery/charging module pairs: a first battery/charging module pair includes Battery <NUM> and Charging Module <NUM> and a second battery/charging module pair includes Battery <NUM> and Charging Module <NUM>. For a particular subdivision to provide the DC power signal to the DC bus, only one of the battery or the charging module of one of the two battery/charging module pairs of the subdivision is required as operative. Thus components may be removed (for maintenance), while the other battery/charging module pair in the channel remains operative. Each of the redundant battery/charging pairs may be a separate and/or independent sub-system.

<FIG> shows a one-line schematic diagram for Subdivision I <NUM> of the common plant PDM <NUM> of <FIG>. Subdivision II of PDM <NUM> may include similar features and/or structures to Subdivision I <NUM>. Subdivision I <NUM> includes two redundant battering/charging module pairs. The first battery/charging module pair includes Charging Module <NUM>, Fused Transfer Switch Module <NUM>, Battery <NUM>, and Battery Monitor <NUM>. The second battery/charging module pair includes Charging Module <NUM>, Fused Transfer Switch Module <NUM>, Battery <NUM>, and Battery Monitor <NUM>.

Subdivision I AC Bus_1 selectively provides an AC power signal to the charging module in the first battery/charging module pair of Subdivision I. Subdivision I AC Bus_2 selectively provides an AC power signal to the charging module in the second battery/charging module pair of Subdivision I. Subdivision II AC Bus_1 selectively provides an AC power signal to the charging module in the first battery/charging module pair of Subdivision II. Subdivision II AC Bus_2 selectively provides an AC power signal to the charging module in the second battery/charging module pair of Subdivision II. The voltage of the provided AC signal may be approximately <NUM> V AC. One or more switches <NUM> may be employed to selectively couple Subdivision I AC Bus_1 and Subdivision I AC Bus_2 the corresponding battery/charging module pair included in Subdivision I <NUM>. As shown in <FIG>, in some embodiments, switches <NUM> may be outside of the PDM that includes Subdivision I <NUM>. In other embodiments, switches <NUM> may be included in the PDM.

As shown in <FIG>, a fused transfer switch module in a battery/charging module pair may selectively couple and decouple each of the batteries to the to the Subdivision I DC bus included in the switchgear module. A fused transfer switch module may include a changeover switch <NUM>, one or more fuses <NUM>, and a battery test terminal. Changeover switch <NUM> may be a double pole changeover switch (DPCO).

The charging modules include one or more circuit breakers to provide protection from an over-voltage, under-voltage, or over-current event. For instance, charging modules may include AC supply breaker <NUM> and DC output breakers <NUM>. The charging modules may also include one or more rectifiers <NUM> to rectify the provided AC power signal. Rectifier <NUM> may include one or more transformers or DC-to-DC converters to output a DC power signal at a voltage that is approximately <NUM> V DC, or at least less than the voltage of the inputted AC signal.

Each battery/charging module pair may include one or more separate battery monitors. A battery monitor may include one or more indicators that indicate a battery current and/or voltage. A battery monitor may also include one or more alarms for battery overvoltage, under-voltage, and high or low room temperature. In some embodiments, each of the batteries may include multiple battery cells. For instance, a battery may include at least <NUM> cells.

In various embodiments, a communication link may be included between the redundant charging modules in each of the Subdivision I and Subdivision II. A communication link between charging modules may enable the two charging modules to share providing DC power to a single DC bus. Accordingly, in the various embodiments, multiple charging modules are enabled to share in the supplying DC power to the various DC bus loads. For instance, in <FIG>, communication link <NUM> is included between Charging Module <NUM> and Charging Module <NUM> for Subdivision I. Communication link <NUM> may include load sharing circuity to enable Charging Module <NUM> and Charging Module <NUM> to share providing DC power to the DC bus for Subdivision I. It should also be noted that Charging Module <NUM> of Subdivision I is enabled to charge Battery <NUM> while simultaneously providing DC power to the DC bus for Subdivision I. Furthermore, Charging Module <NUM> of Subdivision I is enabled to charge Battery <NUM> while simultaneously providing DC power to the DC bus for Subdivision I.

At least a portion of the DC bus for Subdivision I <NUM> may be included in a switchgear module. For instance, the switchgear module may include Subdivision I DC bus. As shown, a plurality of switches <NUM> may selectively couple the charging modules and the batteries (via fused transfer switch modules) to the DC bus.

Switchgear module may include another plurality of switches, such as switch <NUM> that selectively couples the DC bus to each of the DC loads associated with and/or assigned to Subdivision I. Switchgear module may include a plurality of circuit breakers, switches, and/or fuses, such as but not limited to fusible disconnect switch <NUM>, to protect the various DC loads from an over voltage and/or over current event. In various embodiments, at least one of the plurality of switches included in the switchgear module may be a double-pole single-throw (DPST) switch. The switchgear module may also include one or more alarms to indicate a change of a switch or breaker status.

Claim 1:
A fault-tolerant power plant system, including:
a power generation module PGM including a modular nuclear reactor, wherein the PGM includes a first group of loads and a second group of loads that are configured to operate the modular nuclear reactor, and wherein the PGM is configured to generate an alternating current AC signal,
a power distribution module PDM electrically coupled to the PGM, the PDM comprising:
a plurality of alternating current AC busses that are configured to receive at least a portion of the AC signal generated by the PGM and provide an input AC signal to the PDM;
a first direct current DC bus that is directly coupled to the first group of loads;
a second DC bus that is directly coupled to the second group of loads;
a first channel having a first rectifier and a first battery, wherein a first one of the plurality of AC busses is configured to provide the input AC signal to the first channel, and wherein
the first rectifier is configured to rectify the input AC signal and selectively provide a first DC signal to the first DC bus when the first one of the plurality of AC busses provides the input AC signal to the first channel, the first DC signal including a first portion of the rectified input AC signal, and
the first battery is configured to selectively provide the first DC signal to the first DC bus when the plurality of AC busses do not provide the input AC signal to the first channel, the first DC signal including energy stored in the first battery; and
a second channel having a second rectifier and a second battery, wherein a second one of the plurality of AC busses is configured to provide the input AC signal to the second channel, and wherein
the second rectifier is configured to rectify the input AC signal and selectively provide a second DC signal to the second DC bus when the second one of the plurality of AC busses provides the input AC signal to the second channel, the second DC signal including a second portion of the rectified input AC signal, and
the second battery is configured to selectively provide the second DC signal to the second DC bus when the plurality of AC busses do not provide the input AC signal to the second channel, the second DC signal including energy stored in the second battery.