Nuclear power plants and methods of generating electricity in nuclear power plants

Abstract

To provide a nuclear power plant and a method for generating power in a nuclear power plant which can improve the load following property of a nuclear power generation plant and can further stabilize the output of a nuclear reactor.SOLUTION: The nuclear power plant having a nuclear reactor includes: an output control unit 70 for controlling the opening degree of an air extraction valve 13 according to a load request; and an energy storage unit for storing renewable energy. The output control unit 70 controls the temperature of water to supply to the nuclear reactor on the basis of the opening degree of the air extraction valve 13 and the amount of stored energy in the energy storage unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a nuclear power plant and a power generation method in a nuclear power plant.

Background Art

[0002] As an example of a technique for improving the load following performance of a nuclear power plant, Patent Document 1 discloses that an output control device includes a turbine driven by steam generated in a nuclear reactor, a generator driven by the turbine to generate electric power, an extraction valve for adjusting the flow rate of extraction steam flowing out from the turbine, and an exhaust valve installed in the exhaust system of the turbine. The output control device is used for a nuclear power plant, and includes a signal processing unit that controls the opening degrees of the extraction valve and the exhaust valve based on the output target value of the nuclear power plant and the actual output value of the generator, and a reactor output setting unit that sets the reactor output. When increasing the load of the turbine, the signal processing unit reduces the opening degrees of the extraction valve and the exhaust valve to temporarily increase the amount of load increase of the turbine, and while temporarily increasing the amount of load increase, the reactor output setting unit performs control to increase the reactor output.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a means for suppressing the emission of carbon dioxide, which is one of the causative substances of global warming, the introduction of a power generation system (renewable energy power generation) using renewable energy represented by sunlight, solar heat, and wind power is being promoted.

[0005] Although renewable energy generation has low conversion efficiency to electricity and a small output scale, it is expected to be used as a major source of electricity in the future because its output can be increased by virtually connecting numerous systems electrically or on the power grid.

[0006] Furthermore, nuclear power generation, which uses uranium as its main fuel, is also an effective means of reducing carbon dioxide emissions. Nuclear power generation generates steam using the heat produced by the nuclear fission reaction of uranium, and this steam is used to drive a turbine to produce electricity. The advantage of nuclear power generation lies in its large output scale, and it is expected to play a fundamental role in the power supply along with renewable energy generation.

[0007] In order to achieve carbon neutrality and curb the progression of global warming, a stable power supply is necessary, which involves coordinating renewable energy and nuclear power generation systems as power sources, as mentioned earlier.

[0008] However, renewable energy generation is subject to fluctuations in output depending on weather, climate, and time of day. Therefore, it is necessary to suppress fluctuations in power supply caused by changes in nuclear power output or the charging and discharging of batteries, as mentioned earlier.

[0009] To address these challenges, for example, Patent Document 1 describes increasing the output of a nuclear power plant by throttling the extraction valve.

[0010] However, as shown in Patent Document 1, restricting the extraction valve lowers the feedwater temperature in the reactor's feedwater system, such as the drain tank, making it clear that there is room to stabilize and improve reactor output.

[0011] The present invention provides a nuclear power plant and a method for generating power in a nuclear power plant that can improve the load-following performance of the nuclear power plant and make the reactor output more stable. [Means for solving the problem]

[0012] The present invention includes multiple means for solving the above problems, but one example is a nuclear power plant equipped with a nuclear reactor, comprising an output control unit that controls the opening degree of an extraction valve in response to load demands, and an energy storage unit that stores renewable energy, wherein the output control unit controls the feedwater temperature to the nuclear reactor based on the opening degree of the extraction valve and the amount of energy stored in the energy storage unit. [Effects of the Invention]

[0013] According to the present invention, it is possible to improve the load-following performance of a nuclear power plant and to stabilize the reactor output. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a nuclear power plant according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram of the nuclear power plant control system according to the first embodiment. [Figure 3] This is an explanatory diagram of the plant load operation by the nuclear power plant and control system according to the first embodiment. [Figure 4] This is a schematic diagram of a nuclear power plant according to a second embodiment of the present invention. [Figure 5] This is a schematic diagram of a nuclear power plant according to a third embodiment of the present invention. [Figure 6] This is a schematic diagram of a nuclear power plant according to a fourth embodiment of the present invention. [Figure 7] This is a schematic diagram of a nuclear power plant according to a fifth embodiment of the present invention. [Modes for carrying out the invention]

[0015] Hereinafter, embodiments of the nuclear power plant and the power generation method in the nuclear power plant of the present invention will be described with reference to the drawings. In the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated descriptions of these components may be omitted.

[0016] <First Embodiment> The first embodiment of the nuclear power plant and the power generation method in the nuclear power plant of the present invention will be described with reference to FIGS. 1 to 3.

[0017] First, the overall configuration of the nuclear power plant will be described with reference to FIG. 1. FIG. 1 is a diagram showing the schematic configuration of the nuclear power plant in this embodiment.

[0018] The nuclear power plant 1 shown in FIG. 1 includes a nuclear reactor 2, a high-pressure steam turbine 3, a moisture separation heater 4, a low-pressure steam turbine 5, a drive shaft 6, a generator 7, a condenser 8, a condensate pump 9, a low-pressure feedwater heater 10, a feedwater pump 11, a high-pressure feedwater heater 12, an extraction valve 13, a drain tank 14, a drain pump 15, a turbine governor 16, a solar heat collector 30, a three-way valve 31, drain heating means 32, a high-temperature tank 33, a heat storage tank 34, a low-temperature tank 35, a heat medium supply pump 36, a heat medium circulation pump 37, a regulating valve 38, an output control unit 70, and the like.

[0019] Among these, the nuclear reactor 2, the high-pressure steam turbine 3, the moisture separation heater 4, the low-pressure steam turbine 5, the drive shaft 6, the generator 7, the condenser 8, the condensate pump 9, the low-pressure feedwater heater 10, the feedwater pump 11, the high-pressure feedwater heater 12, the extraction valve 13, the drain tank 14, the drain pump 15, and the turbine governor 16 preferably serve as the execution main body of the nuclear power generation step of generating steam using the heat generated in the nuclear reactor 2 and rotationally driving the turbine generator to generate electricity.

[0020] Further, the high-pressure steam turbine 3, the moisture separation heater 4, the low-pressure steam turbine 5, the drive shaft 6, and the generator 7 constitute a turbine generator.

[0021] Furthermore, the solar collector 30, three-way valve 31, drain heating means 32, high-temperature tank 33, heat storage tank 34, low-temperature tank 35, heat medium supply pump 36, heat medium circulation pump 37, and control valve 38 constitute an energy storage unit for storing solar energy, which is a type of renewable energy, and preferably serves as the main body for executing the energy storage step of storing renewable energy.

[0022] The following describes specific examples of each configuration.

[0023] In Figure 1, reactor 2 represents a boiling water reactor as an example, but reactors are not limited to boiling water reactors. A boiling water reactor has a pressure vessel that is filled with cooling water up to a certain level and contains fuel rods. The reactor is loaded with control rods to control the nuclear fission of the fuel rods, and the position of the control rods determines the rate of fission. When the control rods are withdrawn, the nuclear fission reaction proceeds, and the heat generated causes the cooling water inside reactor 2 to boil, producing steam from the top of reactor 2.

[0024] The steam generated in reactor 2 passes through turbine governor 16 and then drives high-pressure steam turbine 3. The exhaust steam from high-pressure steam turbine 3 is reheated in moisture separator heater 4 with a portion of the steam from reactor 2 and drives low-pressure steam turbine 5. The driving force of high-pressure steam turbine 3 and low-pressure steam turbine 5 is transmitted via drive shaft 6 to rotate generator 7, thereby generating electricity.

[0025] After driving the low-pressure steam turbine 5, the steam is condensed in the condenser 8 and supplied to the low-pressure feedwater heater 10 by the condensate pump 9. In the low-pressure feedwater heater 10, the feedwater is heated using extracted steam taken from the intermediate stage of the low-pressure steam turbine 5. This feedwater is pressurized by the feedwater pump 11 and supplied to the high-pressure feedwater heater 12. In the high-pressure feedwater heater 12, the feedwater is heated using extracted steam taken from the intermediate stage of the high-pressure steam turbine 3. The heated feedwater is then reintroduced into the reactor 2.

[0026] Steam extracted from the low-pressure steam turbine 5 and used to heat the feedwater in the low-pressure feedwater heater 10 is stored as condensate at the bottom of the low-pressure feedwater heater 10 before being recirculated to the condenser 8. Steam extracted from the high-pressure steam turbine 3 and used to heat the feedwater in the high-pressure feedwater heater 12 is stored as condensate in a drain tank 14 located below the high-pressure feedwater heater 12 before being pressurized by the drain pump 15 and recirculated to the inlet of the feedwater pump 11.

[0027] As a means of utilizing renewable energy in the nuclear power plant 1 described above, in this embodiment, a heat storage tank 34 is used to store the heat energy collected by a solar collector 30 that collects solar thermal energy, and the water supplied to the drain tank 14 is heated as needed.

[0028] Here, the solar collector 30 is a device that collects thermal energy from the sun and heats the heat transfer medium flowing inside it. Solar collectors 30 can be of various types, such as trough type or Fresnel type, and some are equipped with mechanisms to increase the amount of heat collected by adjusting the angle of the collector body according to the sun's altitude. In this embodiment, water is assumed to be the heat transfer medium, but other liquids with high heat capacity can be used and are not particularly limited.

[0029] In this embodiment, the solar collector 30 operates in four operating modes—"heat storage operation," "heat release operation," "direct heating operation," and "idle operation"—under the control of the output control unit 70. Each operation will be described below.

[0030] In "thermal storage operation," the heat transfer medium heated by the solar collector 30 is supplied to the thermal storage tank 34 via the three-way valve 31. The thermal storage tank 34 is filled with a second heat transfer medium, and the heat from the first heat transfer medium is used to heat the second heat transfer medium. The second heat transfer medium is supplied from the low-temperature tank 35. The second heat transfer medium heated in the thermal storage tank 34 is stored in the high-temperature tank 33. After heating the second heat transfer medium, the heat transfer medium is returned from the thermal storage tank 34 to the heat transfer medium supply pump 36 via the control valve 38. The heat transfer medium circulation pump 37 is stopped, and there is no flow of heat transfer medium within the drain heating means 32.

[0031] In "heat dissipation operation," the thermal energy of the second heat transfer medium stored in the high-temperature tank 33 is used to heat the drain stored in the drain tank 14. The heat transfer medium circulation pump 37 is started, and the second heat transfer medium stored in the high-temperature tank 33 is used to heat the heat transfer medium in the heat storage tank 34. After heating the heat transfer medium, the second heat transfer medium is moved to and stored in the low-temperature tank 35. The heat transfer medium heated in the heat storage tank 34 is supplied to the drain heating means 32 at the bottom of the drain tank 14 via the three-way valve 31, heating the drain in the drain tank 14. After heating, the heat transfer medium is returned to the heat transfer medium circulation pump 37. The heat transfer medium supply pump 36 is stopped, and there is no flow of heat transfer medium inside the solar collector 30.

[0032] In "direct heating operation," the heat transfer medium heated by the solar collector 30 is used directly to heat the drain tank 14. The heat transfer medium supply pump 36 is started, and the heat transfer medium heated by the solar collector 30 is supplied via the three-way valve 31 to the drain heating means 32 at the bottom of the drain tank 14, heating the drain in the drain tank 14. After heating, the heat transfer medium is returned to the heat transfer medium supply pump 36 via the control valve 38. The heat transfer medium circulation pump 37 is stopped, and there is no flow of heat transfer medium within the thermal storage tank 34.

[0033] In "idle operation," the heat of the second heat transfer medium stored in the high-temperature tank 33 is maintained, and the heat transfer medium circulation pump 37 is stopped while the heat transfer medium is circulated through the heat transfer medium supply pump 36, solar collector 30, three-way valve 31, heat storage tank 34, and control valve 38 to prevent the heat transfer medium from freezing.

[0034] Next, the method of output control by a nuclear power plant using renewable energy in this embodiment will be explained using Figure 1 again.

[0035] In this embodiment, reactor 2 operates at a constant output regardless of electricity demand and renewable energy output, and the operation of the feedwater condensate system and the solar collector 30 is switched according to electricity demand and renewable energy output and storage amount.

[0036] For example, when electricity demand is high and renewable energy output is high, that is, during daytime operations in summer, the reactor 2 is operated at a constant output, and extraction throttling operation is performed by throttling the extraction valve 13 provided on the high-pressure steam turbine 3. Extraction throttling operation is an operation that increases the amount of fluid passing through the turbine by throttling (reducing the amount) of steam extracted from the intermediate stage of the turbine, thereby increasing the turbine output and, consequently, the power generation output. Extraction throttling operation increases the electrical output from the generator 7, making it possible to meet electricity demand.

[0037] On the other hand, throttling the extraction valve 13 reduces the amount of extracted steam to the high-pressure feedwater heater 12, thus lowering the feedwater temperature at the outlet of the high-pressure feedwater heater 12. The decrease in feedwater temperature can be measured using the feedwater thermometer 50. In reactor 2, a decrease in feedwater temperature can cause changes in the reaction state within the core, potentially leading to unexpected fluctuations in reactor output.

[0038] In this embodiment, when load control is performed by throttling the extraction valve 13, the system operates in a "direct heating operation" mode, where the thermal energy collected by the solar collector 30 is used to heat the drain in the drain tank 14, and the heated drain is returned to the feedwater to heat the feedwater. In other words, the heat from the solar collector 30 is used directly to heat the drain tank 14. The drain stored in the drain tank 14 is returned to the inlet of the feedwater pump 11 via the drain pump 15. By returning the heated drain to the feedwater, the decrease in the feedwater temperature in the high-pressure feedwater heater 12 is suppressed, thereby reducing the impact on the reactor 2.

[0039] Next, when electricity demand is low and renewable energy output is high, that is, during daytime operations in spring and autumn, reactor 2 is operated at a constant output to meet electricity demand. In addition, the solar collector 30 is operated in "thermal storage operation," and the thermal energy of the heat transfer medium heated by the solar collector 30 is stored in the high-temperature tank 33 via the thermal storage tank 34. In other words, the drain is not heated.

[0040] Next, when electricity demand is high and renewable energy output is low, that is, during operation during the daytime in winter or at night in summer, reactor 2 is operated at a constant output, and extraction throttling operation is performed by throttling the extraction valve 13 to meet the electricity demand. By throttling the extraction valve 13, the amount of extracted steam to the high-pressure feedwater heater 12 decreases, and the feedwater temperature of the high-pressure feedwater heater 12 also decreases.

[0041] Therefore, when the load is controlled by throttling the extraction valve 13, in this embodiment, the system operates in a "heat dissipation operation" mode in which the heat energy collected by the solar collector 30 is used to heat the drain in the drain tank 14, and the heated drain is returned to the feedwater to heat the feedwater. The heat accumulated in the high-temperature tank 33 is supplied to the drain tank 14 via the heat storage tank 34 to heat the drain. By returning the heated drain water to the feedwater, the decrease in the feedwater temperature in the high-pressure feedwater heater 12 is suppressed, thereby suppressing the impact on the reactor 2.

[0042] Finally, when electricity demand is low and renewable energy output is also low, such as at nights in spring and autumn or at night in winter, the system operates in "idle operation," with reactor 2 running at a constant output to meet electricity demand. The heat transfer fluid circulation pump 37 is stopped, and the heat in the high-temperature tank 33 is maintained while the heat transfer fluid is circulated through the heat transfer fluid supply pump 36, solar collector 30, three-way valve 31, heat storage tank 34, and control valve 38 to prevent the heat transfer fluid from freezing.

[0043] In this case, if the amount of heat stored in the second heat transfer medium in the high-temperature tank during "heat dissipation operation" or "direct heating operation" (determined from the temperature of the heat transfer medium and the amount of heat transfer medium in the high-temperature tank) falls below a specified value, the solar collector 30 stops operating.

[0044] The above examples of operation were explained in relation to typical electricity demand and renewable energy output, such as seasons and day / night cycles. However, in actual operation, the switching will be done hourly and will not be limited to the seasons or time periods mentioned above. For example, even during the daytime in summer, in the event of severe weather such as a typhoon, when electricity demand is high and renewable energy output is low, the solar collector 30 will be operated in "heat dissipation mode".

[0045] Furthermore, the "specified value" that serves as the criterion for deciding whether to switch "electricity demand and renewable energy output" is a value that depends on the output of the plant, the output of the renewable energy sources it comprises, and the composition of electricity consumers, and is determined appropriately according to the configuration.

[0046] Next, the details of the control system and control method in the output control unit 70 of the nuclear power plant 1 according to the present invention will be explained with reference to Figure 2. Figure 2 is a block diagram showing the control system necessary to control the nuclear power plant 1 using the extraction valve and the solar collector 30.

[0047] The output control unit 70 is the part that collects, calculates, and outputs data from various sensors installed within the nuclear power plant 1 in order to monitor the status of the nuclear power plant 1.

[0048] Figure 2 shows the configuration of the output control unit 70. The output control unit 70 consists of a nuclear power plant control device 60 and a solar collector control device 61. Of these, the solar collector control device 61 consists of an output control unit 62, an operation decision unit 63, a heat storage / heating control unit 64, a heat dissipation control unit 65, and a control valve control unit 66. This output control unit 70 is the main entity that executes the output control step, which controls the opening degree of the extraction valve in response to load demands.

[0049] This output control unit 70 may be configured as hardware using a dedicated circuit board, or it may be configured as software executed on a computer. When configured as hardware, it can be realized by integrating multiple arithmetic units that perform processing on a wiring board, or within a semiconductor chip or package. When configured as software, it can be realized by equipping a computer with a high-speed general-purpose CPU and executing a program that performs the desired arithmetic processing.

[0050] The nuclear power plant control device 60 can be the same one already in practical use as a control device for a typical boiling water reactor nuclear power plant. It takes input values ​​of power demand and reactor pressure, and sends out commands for turbine governor opening, feedwater pump output, drain pump output, control rod position, and recirculation pump output. The nuclear power plant control device 60 is used for starting and stopping the nuclear power plant 1, as well as for achieving base-load operation.

[0051] On the other hand, the solar collector control device 61 is used to control the plant in the extraction throttling operation in the present invention, as well as in the aforementioned "heat dissipation operation," "heat storage operation," "direct heating operation," and "idle operation." Power demand (load request) is input, and the output control unit 62 sends the opening degree of the extraction valve 13.

[0052] Furthermore, the operation determination unit 63 is the part that determines whether to switch between heating the drain using the thermal energy stored in the solar thermal collector 30, storing thermal energy in the solar thermal collector 30, heating the drain using the thermal energy in the solar thermal collector 30, and an idle state, based on the load request and the amount of heat stored in the solar thermal collector 30. It takes the power demand and the temperature of the heat medium at the outlet of the solar thermal power generation as input and outputs one of the three types of operation as an operation mode command. It also sends an opening command for the three-way valve 31 according to each operation mode.

[0053] The heat storage / heating control unit 64 receives the operation mode command and the amount of heat stored in the high-temperature tank 33, and sends an output command for the heat transfer medium supply pump 36. If the amount of heat stored in the high-temperature tank 33 exceeds the specified range, heat storage is stopped.

[0054] The heat dissipation control unit 65 receives the operation mode command and the amount of heat stored in the high-temperature tank 33 as input and sends an output command for the heat transfer fluid circulation pump 37. If the amount of heat stored in the high-temperature tank 33 falls below the specified range, heat dissipation is stopped. The control valve control unit 66 sends an opening command for the control valve 38 according to each operation mode.

[0055] Next, we will explain the operating characteristics of the nuclear power plant when the solar collector 30 is in "heat dissipation operation" or "direct heating operation" using Figure 3. Figure 3 is a time-series graph showing the operating characteristics of each part of the plant when extraction throttling operation is performed in accordance with increases and decreases in electricity demand, that is, when the nuclear power plant is operated under load.

[0056] In Figure 3, the horizontal axis represents time, with load increase occurring at time T1 and load decrease occurring at time T2. The vertical axis, from a to e, represents the operating characteristics of each part within the plant, and the rated operating state is normalized to 100% for illustrative purposes.

[0057] In Figure 3, axis a represents the power output, and the load requirement and actual load are illustrated, respectively. When the load requirement increases at time T1, the actual load on axis a is increased by throttling the extraction valve opening shown on axis b. As the extraction throttling operation reduces the amount of extracted steam from the high-pressure steam turbine 3, the amount of water held in the drain tank 14 on axis c decreases. On the other hand, as a result of heating the drain using a heat transfer medium, the drain temperature in the drain tank 14 on axis d rises. By recirculating this drain to the inlet of the feedwater pump 11, the feedwater temperature shown on axis e decreases temporarily and then recovers to the rated temperature.

[0058] The feedwater temperature during extraction throttling is also indicated on axis e. As a result of suppressing the decrease in feedwater temperature during extraction throttling by the present invention, the amount of heat supplied to the feedwater to reactor 2 can be maintained at the level of rated operation, thereby suppressing changes in the reaction state within the reactor core.

[0059] The effect of reducing extraction pressure on power output is estimated to be approximately 3-5% of the rated power output, although this depends on the amount of air extracted from the turbine stage. Assuming that the output of nuclear power plant 1 is approximately 1 GW, the increase in output is estimated to be 30-50 MW. This is equivalent to the output of one to two small-to-medium-capacity coal-fired or oil-fired power plants. These thermal power plants function as a balancing force to compensate for fluctuations in the output of renewable energy and maintain a stable supply-demand balance. However, if thermal power plants are phased out in order to achieve carbon neutrality, the nuclear power plant according to the present invention can be used as a substitute for thermal power plants.

[0060] Thus, the solar collector control device 61 in the present invention can be added to the control device of an already operating nuclear power plant, and existing nuclear power plants can be easily adapted to load operation that can handle renewable energy as in the present invention through simple construction work such as adding an extraction valve 13 and adding a drain heating means to the bottom of the drain tank 14. Furthermore, since the decrease in feedwater temperature that occurs during extraction throttling operation is compensated for by drain heating, there is no need to change the operating method of the reactor 2, and the hurdle for application to existing facilities can be made very low. It should be noted that it is not limited to application to existing plants, but can of course also be applied to newly constructed plants.

[0061] Next, the effects of this embodiment will be described.

[0062] The nuclear power plant 1, equipped with the reactor and turbine generator of the first embodiment of the present invention described above, includes an output control unit 70 that controls the opening degree of the extraction valve 13 in response to load demands, and an energy storage unit that stores renewable energy. The output control unit 70 controls the feedwater temperature to the reactor based on the opening degree of the extraction valve 13 and the amount of energy stored in the energy storage unit.

[0063] In this system, extraction throttling is employed to increase the amount of steam passing through the steam turbine by restricting the amount of extracted steam from the steam turbine, thereby increasing turbine output. This operation enables load operation even in nuclear power plants, and fluctuations in renewable energy generation due to weather, climate, and day / night cycles can be mitigated by load operation of the nuclear power plant. Furthermore, although the feedwater temperature decreases as a result of the reduced amount of extracted steam flowing into the feedwater heater due to extraction throttling, it is possible to maintain the feedwater at the set temperature by accumulating renewable energy and returning it to the plant as heat as needed. Therefore, fluctuations in thermal energy due to weather, climate, and day / night cycles can be mitigated, and it becomes possible to utilize it stably as heat.

[0064] In other words, a decrease in feedwater temperature leads to changes in the operating state of the reactor, causing fluctuations such as a decrease in the void fraction within the reactor and a corresponding increase in thermal output. However, according to the present invention, it is possible to maintain a high feedwater temperature, thereby suppressing fluctuations in the operating state of reactor 2 compared to conventional methods, and enabling more stable and safer plant operation. Consequently, by incorporating renewable energy generation, which is an asynchronous power source, as part of the plant, and utilizing renewable energy to achieve carbon neutrality while operating the nuclear power plant under load, it becomes possible to maintain the balance of power supply and demand and the power quality of the power grid.

[0065] Furthermore, the energy storage unit includes a solar collector 30 that collects solar thermal energy, and a thermal storage tank 34 that stores the thermal energy collected by the solar collector 30. The feedwater heating unit, when the load is controlled by throttling the extraction valve 13, uses the thermal energy collected by the solar collector 30 to heat the drain in the drain tank 14, and the heated drain is returned to the feedwater to heat the feedwater. This makes it possible to easily control the temperature of the feedwater of the reactor 2, which fluctuates with the operation of the plant, by adjusting the drain flow rate in the drain tank 14.

[0066] Furthermore, by adding an operation determination unit 63 that makes a decision on switching between heating the drain using the thermal energy stored in the solar collector 30, storing thermal energy in the solar collector 30, and heating the drain using the thermal energy in the solar collector 30, based on the load request and the amount of heat stored in the solar collector 30, it becomes possible to automatically determine the appropriate operating conditions.

[0067] Furthermore, the output control unit 70 can achieve more appropriate operation by changing the use and storage of renewable energy in the energy storage unit according to the power demand and the output of renewable energy.

[0068] <Second Example> A nuclear power plant and a power generation method in a nuclear power plant according to a second embodiment of the present invention will be explained with reference to Figure 4. Figure 4 is a diagram showing the schematic configuration of the nuclear power plant in this embodiment.

[0069] The nuclear power plant 1A of this embodiment, shown in Figure 4, differs from the nuclear power plant 1 shown in Figure 1 in that its energy storage unit includes a photovoltaic power generation panel 40 that obtains electricity from solar light energy, and a storage battery 44 that stores the electricity obtained by the photovoltaic power generation panel 40. Furthermore, when the load is controlled by throttling the extraction valve 13, the electricity obtained by the storage battery 44 is converted into thermal energy to heat the drain in the drain tank 14, and the heated drain is returned to the feedwater to heat the feedwater.

[0070] The electric heater 45 is a resistor that generates heat when an electric current is passed through it, and uses electricity to heat and maintain the temperature of the drain tank 14. The electricity for the electric heater 45 is supplied from the solar power generation panel 40 via the inverter 41, circuit breaker 42, and distribution board 43. In this embodiment, a storage battery 44 is also provided as a means of storing electricity, and the electricity obtained from the solar power generation panel 40 is stored in the storage battery 44.

[0071] Although this example describes supplying electricity from solar panels 40 to electric heaters 45, a configuration that stores electricity from wind turbines in addition to solar panels 40 can also be adopted. In this case, solar panels 40 and wind turbines are not mutually exclusive; both can be used simultaneously.

[0072] In this embodiment, the solar power generation system can be operated in three modes: "energy storage operation," "heating operation," and "direct heating operation."

[0073] In "energy storage operation," the electricity generated by the solar power generation panels 40 is supplied to the battery 44 via the distribution board 43.

[0074] In "heating operation," the electricity stored in the battery 44 is supplied to the electric heater 45 via the distribution board 43 to heat the drain in the drain tank 14.

[0075] In "direct heating operation," the electricity generated by the solar power generation panel 40 is supplied to the electric heater 45 via the distribution board 43 to heat the drain in the drain tank 14.

[0076] Other configurations and operations are substantially the same as those of the nuclear power plant and power generation method in the first embodiment described above, and details are omitted.

[0077] In the second embodiment of the present invention, a nuclear power plant and a power generation method in the nuclear power plant also provide substantially the same effects as those of the first embodiment described above. Specifically, by storing solar energy or wind energy as electricity in the battery 44 and heating the plant feedwater during extraction throttling operation, fluctuations in thermal energy due to weather, climate, and day / night cycles can be mitigated, enabling stable load operation of the nuclear power plant. Furthermore, similar to the first embodiment, by incorporating renewable energy generation, which is an asynchronous power source, into part of the plant, it is possible to contribute to maintaining both the balance of power supply and demand and the power quality of the power grid.

[0078] <Third Example> A third embodiment of the present invention, a nuclear power plant, and a power generation method in the nuclear power plant will be described with reference to Figure 5. Figure 5 is a diagram showing the schematic configuration of the nuclear power plant in this embodiment.

[0079] The nuclear power plant 1B of this embodiment, shown in Figure 5, differs from the nuclear power plant 1 shown in Figure 1 in that it is equipped with a heat exchanger 39 as a method for heating the drain, and when the load is controlled by throttling the extraction valve 13, the thermal energy obtained from the solar solar collector 30 (heat transfer medium from the high-temperature tank 33 or heat transfer medium heated by the solar solar collector 30) is supplied to the heat exchanger 39 to heat the drain at the outlet of the drain pump 15, and the heated drain is returned to the feedwater to heat the feedwater.

[0080] Similar to the first embodiment, in this embodiment as well, the solar collector 30 is operated in four types: "heat storage operation," "heat release operation," "direct heating operation," and "idle operation." In "heat storage operation," the heat transfer medium heated by the solar collector 30 is supplied to the heat storage tank 34 via the three-way valve 31, heating the second heat transfer medium filling the heat storage tank 34. After heating, the second heat transfer medium is stored in the high-temperature tank 33. In "heat release operation," the second heat transfer medium stored in the high-temperature tank 33 is supplied to the heat storage tank 34, heating the heat transfer medium, and this heat transfer medium is supplied to the heat exchanger 39, thereby heating the drain at the outlet of the drain pump 15. In "direct heating operation," the heat transfer medium heated by the solar collector 30 is supplied to the heat exchanger 39, thereby heating the drain at the outlet of the drain pump 15. There is no particular difference in "idle operation."

[0081] Other configurations and operations are substantially the same as those of the nuclear power plant and power generation method in the first embodiment described above, and details are omitted.

[0082] In the third embodiment of the present invention, a nuclear power plant and a method for generating power in a nuclear power plant can be obtained with substantially the same effects as the nuclear power plant and method for generating power in a nuclear power plant described in the first embodiment.

[0083] Furthermore, this third embodiment is not limited to a configuration in which the drain at the outlet of the drain pump 15 is heated by supplying a heat source to the heat exchanger 39, but can also be configured in which the drain at the outlet of the drain pump 15 is heated by an electric heating element using electricity obtained from a solar power generation panel 40 or a wind turbine, as in the second embodiment.

[0084] <Fourth Example> A fourth embodiment of the present invention, a nuclear power plant, and a method of generating electricity in the nuclear power plant will be described with reference to Figure 6. Figure 6 is a diagram showing the schematic configuration of the nuclear power plant in this embodiment.

[0085] The nuclear power plant 1C of this embodiment, shown in Figure 6, differs from the nuclear power plant 1 shown in Figure 1 in that the high-pressure steam turbine 3 does not have an extraction valve 13, and extraction throttling operation is performed using an extraction valve 17 provided on the low-pressure steam turbine 5. Extraction throttling operation increases the electrical output from the generator 7 to meet the electricity demand.

[0086] In the nuclear power plant 1C of this embodiment, throttling the extraction valve 17 reduces the amount of extracted steam to the low-pressure feedwater heater 10, and also reduces the feedwater temperature at the outlet of the low-pressure feedwater heater 10. The decrease in feedwater temperature can be measured using the low-pressure feedwater thermometer 51.

[0087] Similar to the first embodiment, in this embodiment the solar collector 30 is operated in four modes: "heat storage operation," "heat release operation," "direct heating operation," and "idle operation." Of these, there is no particular difference in "idle operation."

[0088] In the "thermal storage operation," similar to the first embodiment, the heat transfer medium heated by the solar collector 30 is supplied to the thermal storage tank 34 via the three-way valve 31, and thermal energy is stored in the high-temperature tank 33 by heating the second heat transfer medium.

[0089] In "heat dissipation operation," the second heat transfer medium stored in the high-temperature tank 33 is supplied to the heat storage tank 34, heating the heat transfer medium flowing through the heat storage tank 34. This heat transfer medium is also used to heat the drain stored in the drain tank 14. By supplying the heated drain to the inlet of the feedwater pump 11, the feedwater temperature at the outlet of the low-pressure feedwater heater 10, which has decreased due to the extraction throttling operation, is increased.

[0090] In "direct heating operation," the drain tank 14 is directly heated by the heat transfer medium heated by the solar collector 30. By supplying the heated drain to the inlet of the water supply pump 11, the water supply temperature at the outlet of the low-pressure water heater 10, which has decreased due to the extraction throttling operation, is increased.

[0091] Other configurations and operations are substantially the same as those of the nuclear power plant and power generation method in the first embodiment described above, and details are omitted.

[0092] In the fourth embodiment of the present invention, a nuclear power plant and a method for generating power in a nuclear power plant can be obtained with substantially the same effects as the nuclear power plant and method for generating power in a nuclear power plant described in the first embodiment.

[0093] In addition, in this fourth embodiment, the drain in the drain tank 14 can also be heated by heating wires using electricity obtained from a solar power generation panel 40 or a wind turbine, as in the second embodiment.

[0094] <Example 5> A fifth embodiment of the present invention, a nuclear power plant, and a method of generating electricity in the nuclear power plant, will be described with reference to Figure 7. Figure 7 is a diagram showing the schematic configuration of the nuclear power plant in this embodiment.

[0095] The nuclear power plant 1D of this embodiment, shown in Figure 7, differs from the nuclear power plant 1 shown in Figure 1 in that it is equipped with a heat exchanger 46 at the outlet of the high-pressure feedwater heater 12, and that it uses thermal energy obtained from the solar collector 30 to heat the feedwater at the outlet of the high-pressure feedwater heater 12.

[0096] In this embodiment, during extraction throttling operation, the amount of extracted steam to the high-pressure feedwater heater 12 decreases and the feedwater temperature drops by throttling the extraction valve 13. The drop in feedwater temperature can be measured using the feedwater thermometer 50. Therefore, the feedwater is heated using a heat transfer medium heated by the solar collector 30 or a heat transfer medium heated by heat stored in the high-temperature tank 33 to compensate for the drop in feedwater temperature. Similar to the first embodiment, in this embodiment the solar collector 30 is operated in four types: "heat storage operation", "heat release operation", "direct heating operation", and "idle operation".

[0097] In the "thermal storage operation," similar to the first embodiment, the heat transfer medium heated by the solar collector 30 is supplied to the thermal storage tank 34 via the three-way valve 31, and thermal energy is stored in the high-temperature tank 33 by heating the second heat transfer medium.

[0098] In "heat dissipation operation," the thermal energy stored in the high-temperature tank 33 is used to raise the feedwater temperature at the outlet of the high-pressure feedwater heater 12, which has decreased due to the extraction throttling operation.

[0099] In "direct heating operation," the water supply is directly heated using a heat transfer medium heated by the solar collector 30.

[0100] Other configurations and operations are substantially the same as those of the nuclear power plant and power generation method in the first embodiment described above, and details are omitted.

[0101] In the fifth embodiment of the present invention, a nuclear power plant and a method for generating power in a nuclear power plant can be obtained with substantially the same effects as the nuclear power plant and method for generating power in a nuclear power plant described in the first embodiment.

[0102] Furthermore, this fifth embodiment is not limited to a configuration in which the feedwater is heated at the outlet of the high-pressure feedwater heater 12 by supplying it to the heat exchanger 46. The feedwater at the outlet of the high-pressure feedwater heater 12 can be heated by electric heating wires using electricity obtained from a solar power generation panel 40 or a wind turbine, as in the second embodiment.

[0103] <Other> It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. The embodiments described above are explained in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described.

[0104] Furthermore, it is possible to replace parts of the configuration of one embodiment with parts of the configuration of another embodiment, and it is also possible to add parts of the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with parts of other configurations. [Explanation of Symbols]

[0105] 1, 1A, 1B, 1C, 1D… Nuclear power plants 2…Nuclear reactor 3. High-pressure steam turbine 4…Moisture separation heater 5. Low-pressure steam turbine 6…Drive shaft 7…Generator 8...Condenser 9…Condensate pump 10... Low-pressure feedwater heater 11…Water supply pump 12…High-pressure water heater 13, 17… Exhaust valve 14…Drain tank 15…Drain pump 16... Turbine Governor 30…Solar collector 31... Three-way valve 32... Drain heating means 33...High temperature bath 34...Heat storage tank 35...Cryogenic chamber 36… Heat transfer fluid supply pump 37… Heat transfer fluid circulation pump 38... Adjustment valve 39,46…Heat exchanger 40…Solar power generation panels 41…Inverter 42... Barrier 43... Distribution board 44… Storage battery 45...Electric heater 50…Feed water thermometer 51... Low-pressure water supply temperature gauge 60… Nuclear power plant control system 61…Solar collector control device 62…Output control unit 63... Driving Decision Unit 64…Heat storage / heating control unit 65…Heat dissipation control unit 66... ​​Control valve control unit 70, 70A, 70B, 70C, 70D… Output control unit

Claims

1. A nuclear power plant equipped with a nuclear reactor, An output control unit that controls the opening degree of the extraction valve in response to load requirements, It comprises an energy storage unit for storing renewable energy, The energy storage unit includes a solar collector for collecting solar thermal energy, and a thermal storage tank for storing the thermal energy collected by the solar collector. The output control unit controls the temperature of the feedwater to the reactor based on the opening degree of the extraction valve and the amount of energy stored in the energy storage unit. When the load is controlled by throttling the aforementioned extraction valve, the thermal energy collected by the solar collector is used to heat the drain in the drain tank, and the drain is returned to the feedwater, Based on the load requirements and the amount of heat stored in the solar collector, a decision is made to switch between heating the drain using the thermal energy stored in the solar collector, storing thermal energy in the solar collector, and heating the drain using the thermal energy in the solar collector. Nuclear power plant.

2. A nuclear power plant comprising a nuclear reactor, An output control unit that controls the opening degree of the extraction valve in response to load requirements, It comprises an energy storage unit for storing renewable energy, The energy storage unit includes a photovoltaic panel that obtains electricity from solar light energy, and a storage battery that stores the electricity obtained from the photovoltaic panel. The output control unit controls the temperature of the feedwater to the reactor based on the opening degree of the extraction valve and the amount of energy stored in the energy storage unit, and when load control is performed by throttling the extraction valve, it converts the power obtained from the storage battery into thermal energy to heat the drain in the drain tank and returns the heated drain to the feedwater. Nuclear power plant.

3. In the nuclear power plant according to claim 1 or 2, The output control unit stores the renewable energy in the energy storage unit when the power demand is lower than a specified value and the output of renewable energy is equal to or greater than a specified value. Nuclear power plant.

4. In the nuclear power plant according to claim 1 or 2, The output control unit shall, when the power demand is above a specified value and the output of renewable energy is below a specified value, use the renewable energy stored in the energy storage unit to heat the water supply. Nuclear power plant.

5. In the nuclear power plant according to claim 1 or 2, The output control unit shall, when the power demand and the output of renewable energy are above a specified value, use the renewable energy stored in the energy storage unit to heat the water supply. Nuclear power plant.

6. In the nuclear power plant according to claim 1 or 2, The output control unit shall, when the power demand and the output of renewable energy are lower than specified values, keep the renewable energy stored in the energy storage unit. Nuclear power plant.

7. A method of generating electricity in a nuclear power plant equipped with a nuclear reactor, A nuclear power generation step in which steam is generated using the heat generated in the aforementioned nuclear reactor to rotate and drive a turbine generator to generate electricity, An energy storage step for storing renewable energy using a solar collector that collects solar thermal energy and a thermal storage tank that stores the thermal energy collected by the solar collector, It includes an output control step that controls the opening degree of the extraction valve in response to load requirements, In the output control step, the temperature of the feedwater to the reactor is controlled based on the opening degree of the extraction valve and the amount of energy stored in the energy storage step. When the load is controlled by throttling the aforementioned extraction valve, the thermal energy collected by the solar collector is used to heat the drain in the drain tank, and the drain is returned to the feedwater, Based on the load requirements and the amount of heat stored in the solar collector, a decision is made to switch between heating the drain using the thermal energy stored in the solar collector, storing thermal energy in the solar collector, and heating the drain using the thermal energy in the solar collector. Methods of generating electricity at nuclear power plants.

8. A method for generating electricity in a nuclear power plant equipped with a nuclear reactor, A nuclear power generation step in which steam is generated using the heat generated in the aforementioned nuclear reactor to rotate and drive a turbine generator to generate electricity, An energy storage step for storing renewable energy using a solar power generation panel that obtains electricity from solar light energy, and a storage battery that stores the electricity obtained from the solar power generation panel, It includes an output control step that controls the opening degree of the extraction valve in response to load requirements, In the output control step, the temperature of the feedwater to the reactor is controlled based on the opening degree of the extraction valve and the amount of energy stored in the energy storage step. When the load is controlled by throttling the extraction valve, the power obtained from the battery is converted into thermal energy to heat the drain in the drain tank, and the heated drain is returned to the feedwater. Methods of generating electricity at nuclear power plants.

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