Method for controlling output variation of nuclear power plant including small modular reactor

Abstract

The present invention relates to a method for controlling an output variation of a nuclear power plant including a small modular reactor (SMR), wherein the nuclear power plant includes a plurality of small modular reactors, the method comprising the steps of: (a) calculating an output variation amount of each of the small modular reactors; (b) calculating the sum of the calculated output variation amounts and determining whether the calculated sum of the output variation amounts exceeds a preset value; and (c) limiting the output variation of a nuclear reactor in which the output variation amount exceeds the preset value if the sum of the output variation amounts exceeds the preset value.

Description

Method for controlling power fluctuations of a nuclear power plant including a small modular reactor

[0001] The present invention relates to a method for controlling output fluctuations of a nuclear power plant including a small modular reactor.

[0002] Nuclear power plants are an important energy source equipped with high energy density and stable power generation capabilities. Conventional large-scale nuclear power plants generally operate two reactors on a single site, and each plant releases the heat generated during reactor operation into the sea through independent Equipment Cooling Water (CCW) and Equipment Cooling Seawater (ESW) systems.

[0003] Recently installed modular nuclear power plants based on Small Modular Reactors (SMRs) may adopt a design in which multiple modules share CCW and ESW. However, while this design is advantageous for increasing space efficiency and reducing construction costs, it creates problems regarding the capacity of CCW and ESW when multiple modules simultaneously undergo transient situations such as startup, shutdown, or power fluctuations.

[0004] For example, if two reactors start / stop or change power output simultaneously, the thermal load that the CCW and ESW must handle increases. In particular, when power output changes significantly, even greater transient conditions are experienced, which can have a negative impact on the efficiency and stability of the CCW and ESW.

[0005] Therefore, for the safe and efficient operation of modular nuclear power plants based on Small Modular Reactors (SMRs), design and operation strategies for CCW and ESW that consider the simultaneous transient situations of multiple modules are required.

[0006] The objective of the present invention is to provide a method for controlling output fluctuations of a nuclear power plant including a small modular reactor.

[0007] The present invention relates to a method for controlling output fluctuation of a nuclear power plant including a small modular reactor (SMR), wherein the nuclear power plant includes a plurality of said small modular reactors, and comprises: (a) a step of calculating the output fluctuation amount of each said small modular reactor; (b) a step of calculating the sum of the calculated output fluctuation amounts and determining whether the sum of the calculated output fluctuation amounts exceeds a preset value; and (c) a step of limiting the output fluctuation of the reactor whose output fluctuation amount exceeds the preset value when the sum of the output fluctuation amounts exceeds the preset value.

[0008] The output fluctuation amount of step (a) above may be the thermal output fluctuation amount of each of the small modular reactors.

[0009] The above step (a) may include: a step of calculating the current output value of each of the small modular reactors; a step of calculating the target output value of each of the small modular reactors; and a step of calculating the difference between the current output value and the target output value to calculate the output fluctuation amount of each.

[0010] The output variation limiting in step (c) above can be performed by introducing an output variation delay time.

[0011] The above output fluctuation delay time can be set to a value obtained by multiplying the time taken from the startup of the small modular reactor to the attainment of the target output by an arbitrary coefficient.

[0012] The above step (c) may include: a step of activating an output fluctuation prohibition mode when the sum of the output fluctuation amounts exceeds the set value; and a step of delaying the output fluctuation of at least one of the reactors in the output fluctuation prohibition mode.

[0013] Step (c) above limits the output fluctuation of the reactor with the largest output fluctuation among the individual reactors, and can additionally limit the output fluctuation of other reactors when the sum of the output fluctuations approaches the set value.

[0014] The individual small modular reactors mentioned above may share at least one of the equipment cooling water system (CCW) and the equipment cooling seawater system (ESW) for heat removal.

[0015] The above step (c) includes a step of limiting the output fluctuation of at least one of the reactors when the sum of the output fluctuations exceeds the set value; and the output fluctuation limiting step may include a step of resuming the output fluctuation of the reactor whose output fluctuation was limited when the sum of the output fluctuations becomes less than or equal to the set value.

[0016] According to the present invention, a method for controlling output fluctuations of a nuclear power plant including a small modular reactor is provided.

[0017] FIG. 1 is a flowchart illustrating a method for controlling output fluctuation of a nuclear power plant including a small modular reactor according to an embodiment of the present invention, and

[0018] FIGS. 2 and 3 illustrate the operation of individual reactors according to a method for controlling output fluctuations of a nuclear power plant including a small modular reactor according to an embodiment of the present invention, and

[0019] FIGS. 4 to 6 show changes in output at individual reactors according to a method for controlling output fluctuations of a nuclear power plant including a small modular reactor according to an embodiment of the present invention.

[0020] The present invention will be described in more detail below with reference to the drawings.

[0021] The attached drawings are merely examples illustrated to further explain the technical concept of the present invention, and therefore the concept of the present invention is not limited to the attached drawings. Additionally, the sizes and spacing, etc., in the attached drawings may be exaggerated from reality to explain the relationships between the components.

[0022] With reference to FIGS. 1 to 3, a method for controlling output fluctuation of a nuclear power plant including a small modular reactor according to an embodiment of the present invention will be described.

[0023] FIG. 1 is a flowchart illustrating a method for controlling output fluctuations of a nuclear power plant including a small modular reactor according to an embodiment of the present invention, and FIG. 2 and FIG. 3 illustrate the operation of individual reactors according to the method for controlling output fluctuations of a nuclear power plant including a small modular reactor according to an embodiment of the present invention.

[0024] A method for controlling output fluctuations of a nuclear power plant including a small modular reactor according to an embodiment of the present invention first calculates the output fluctuation amounts (ΔP₁, ΔP₂, ...) of each small modular reactor. (S100)

[0025] Here, the nuclear power plant includes multiple small modular reactors, and the output fluctuation amount of each small modular reactor is calculated.

[0026] For example, as illustrated in FIG. 2, in a method for controlling power fluctuations of a nuclear power plant including four small modular reactors (SMRs), the amount of power fluctuation of each reactor can be calculated as ΔP₁, ΔP₂, ΔP₃, and ΔP₄.

[0027] In this case, the output fluctuation can be expressed as a thermal output fluctuation, an electrical output fluctuation, or a combination thereof.

[0028] Additionally, the step (S100) of calculating the output fluctuation amount of each small modular reactor may include the step of calculating the current output value of each small modular reactor, the step of calculating the target output value of each small modular reactor, and the step of calculating the output fluctuation amount of each by calculating the difference between the current output value and the target output value.

[0029] For example, the current output value refers to the current thermal or electrical output value of each reactor, and the target output value refers to the target thermal or electrical output value that each reactor aims to achieve.

[0030] After calculating the output fluctuation amount for each small modular reactor, a step (S200) is performed to determine whether the sum of the calculated output fluctuation amounts (∑|ΔP*?*|) exceeds a set value.

[0031] In one embodiment of the present invention, the sum of the output fluctuations refers to the sum of the absolute values ​​of the output fluctuations of each reactor. For example, as shown in FIG. 2, the sum of the output fluctuations of four reactors can be calculated as |ΔP₁|+|ΔP₂|+|ΔP₃|+|ΔP₄|.

[0032] The setpoint is a value that is pre-set for the stable operation of a nuclear power plant and can be determined by an operator or a system. The setpoint can be set by multiplying the time taken from the startup of a small modular reactor to the attainment of a target output by an arbitrary coefficient (β). Here, the arbitrary coefficient (β) may be a value determined by comprehensively considering the design characteristics of the power plant, safety margins, past operating experience, etc.

[0033] Next, if the sum of the output fluctuations exceeds a set value, a step (S300) of limiting the output fluctuation of at least one of the reactors is performed.

[0034] Output fluctuation limitation can be performed by introducing an output fluctuation delay time. For example, if the sum of the output fluctuation amounts exceeds a set value, an output fluctuation prohibition mode is activated, and in the output fluctuation prohibition mode, the output fluctuation of at least one of the reactors can be delayed.

[0035] The output fluctuation limiting step may include a step of resuming the output fluctuation of the reactor, which had been limited, when the sum of the output fluctuation amounts becomes less than or equal to a set value.

[0036] Specifically, the output fluctuation of the reactor with the largest output fluctuation among individual reactors can be limited, and, if necessary, the output fluctuation of other reactors can be additionally limited.

[0037] For example, as shown in FIG. 3, the output fluctuation of the reactor with the largest output fluctuation among the four reactors can be limited, and the output fluctuation of the remaining reactors can be additionally limited as needed. In this case, individual small modular reactors may share at least one of the equipment cooling water system (CCW) and the equipment cooling seawater system (ESW) for heat removal.

[0038] With reference to FIGS. 4 to 6, a change in output in an individual reactor according to a method for controlling output fluctuation in a nuclear power plant including a small modular reactor according to an embodiment of the present invention will be described.

[0039] FIGS. 4 to 6 show changes in output at individual reactors according to a method for controlling output fluctuations of a nuclear power plant including a small modular reactor according to an embodiment of the present invention.

[0040] With reference to Figures 4 and 5, a nuclear power plant composed of four small modular reactors (SMRs) will be described as an example. When the outputs of each reactor are denoted as P1 (top left), P2 (top right), P3 (bottom left), and P4 (bottom right), the outputs of each reactor can vary independently. That is, P1, P2, P3, and P4 can each have different output values ​​and may exhibit different output variations over time.

[0041] Figure 4 shows the case where P1 and P2 each decrease from 100% to 50% (ΔP1 = -50%, ΔP2 = -50%) when the limit of the total output variation is set to 100%. In this case, the total output variation (ΔP) becomes -100% (|ΔP| = 100%), which is within the limit and is therefore allowed.

[0042] On the other hand, Figure 5 shows a case where P1 changes from 100% to 30% (ΔP1 = -70%) and P2 changes from 100% to 50% (ΔP2 = -50%). In this case, ΔP becomes -120% (|ΔP| = 120%), exceeding the limit of 100%. Therefore, according to the control method of an embodiment of the present invention, ΔP is limited to change only up to -100%. That is, the output fluctuations of P1 and P2 can be adjusted within a range where the sum is -100%, rather than -70% and -50%, respectively.

[0043] For example, P1 can be adjusted to 30% and P2 to 70%, resulting in ΔP1 = -70% and ΔP2 = -30%, or they can be adjusted in other combinations. Here, the specific output fluctuation amounts (ΔP1, ΔP2) of individual reactors can be freely set by considering the operating characteristics of each reactor, for example, the priority and importance of output changes, and the relationship with safety-related systems.

[0044] FIG. 6 shows the situation after the output fluctuation limit described in FIG. 5 has been applied. The remaining output fluctuation amount (-20%), which was limited by the limit value (ΔP = -100%), is allowed after a certain period of time. In one embodiment of the present invention, this time corresponds to a time delay. The time delay serves as a criterion for determining whether the power plant has reached a stable state capable of withstanding additional transient states, and can be set by considering the design characteristics, safety requirements, and operating policies of the power plant.

[0045] For example, quantitative criteria for determining when to start the delay time may be set, such as "the rate of change in output of each reactor is 5% or less" or "the rate of change in temperature of the cooling water system is 1℃ / min or less." Alternatively, qualitative criteria may be applied by the operator to determine whether to start the delay time by comprehensively diagnosing the condition of the power plant.

[0046] If the delay time is set to 30 minutes, the remaining -20% of output fluctuation is allowed after 30 minutes have elapsed since the initial output fluctuation began. This allows the power plant to gradually reach the target output level while avoiding instability caused by excessive output fluctuations.

[0047] In conclusion, the power fluctuation control method according to one embodiment of the present invention limits the total amount of power fluctuations of individual reactors and introduces the concept of 'delay time,' thereby enabling flexible power operation while ensuring the stability of the power plant. In particular, it improves system stability and enables efficient operation by minimizing changes in the thermal load of the cooling water system shared by multiple SMRs.

[0048] In addition, the present invention effectively controls transient states that may occur during SMR output fluctuations, thereby increasing the safety of the power plant, and also ensures stable operation of the SMR even in unpredictable situations, thus providing the effect of improving the reliability of the nuclear power plant.

[0049] The embodiments of the present invention described above and illustrated in the drawings should not be interpreted as limiting the technical scope of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and a person skilled in the art may modify or change the technical scope of the present invention in various forms. Accordingly, such modifications and changes will fall within the scope of protection of the present invention insofar as they are obvious to a person skilled in the art.

Claims

1. A method for controlling power fluctuations of a nuclear power plant including a Small Modular Reactor (SMR), The above nuclear power plant includes a plurality of the above small modular reactors, and (a) a step of calculating the output fluctuation amount of each of the above small modular reactors; (b) a step of calculating the sum of the output fluctuation amounts calculated above and determining whether the sum of the calculated output fluctuation amounts exceeds a preset value; and (C) A method for controlling output fluctuation of a nuclear power plant comprising the step of limiting the output fluctuation of a reactor in which the output fluctuation exceeds the set value when the sum of the output fluctuations exceeds the set value.

2. In Paragraph 1, A method for controlling output fluctuation of a nuclear power plant, wherein the output fluctuation amount of step (a) above is the thermal output fluctuation amount of each of the small modular reactors.

3. In Paragraph 1, The above step (a) is, A step of calculating the current output value of each of the above small modular reactors; A step of calculating the target output value for each of the above small modular reactors; and A method for controlling output fluctuation of a nuclear power plant, comprising the step of calculating the difference between the current output value and the target output value to calculate the respective output fluctuation amount.

4. In Paragraph 1, The output fluctuation limiting of step (c) above is a method for controlling output fluctuation of a nuclear power plant by providing an output fluctuation delay time.

5. In Paragraph 4, The above output fluctuation delay time is, A method for controlling output fluctuation of a nuclear power plant, wherein the value is set by multiplying the time taken from the startup of the above-mentioned small modular reactor to the attainment of the target output by an arbitrary coefficient.

6. In Paragraph 1, The above step (c) is, A step of activating an output fluctuation prohibition mode when the sum of the above output fluctuation amounts exceeds the above set value; and A method for controlling output fluctuation of a nuclear power plant comprising the step of delaying output fluctuation of at least one of the reactors in the above output fluctuation prohibition mode.

7. In Paragraph 6, The above step (c) is, A method for controlling output fluctuation in a nuclear power plant, which limits the output fluctuation of the reactor with the largest output fluctuation among the individual reactors above, and additionally limits the output fluctuation of other reactors when the sum of the output fluctuations approaches the set value above.

8. In Paragraph 1, A method for controlling output fluctuations of a nuclear power plant in which the individual small modular reactors share at least one of an equipment cooling water system (CCW) and an equipment cooling seawater system (ESW) for heat removal.

9. In Paragraph 1, The above step (c) is, The method includes the step of limiting the output fluctuation of at least one of the reactors when the sum of the output fluctuations exceeds the set value. A method for controlling output fluctuation of a nuclear power plant, wherein the output fluctuation limiting step includes the step of resuming the output fluctuation of the reactor, which had been limited, when the sum of the output fluctuation amounts becomes less than or equal to the set value.

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