Method for producing nuclear design core model accounting for load following

Abstract

The present invention relates to a method for producing a nuclear design core model accounting for load following, the method comprising the steps of: receiving load-following requirements for a corresponding cycle, wherein the load-following requirements include the amount of power reduction, the number of load-following operations, and at least one of the time or duration of operation at reduced power; determining the amount of insertion of a control rod on the basis of the load-following requirements; determining the duration of insertion of the control rod on the basis of the amount of insertion of the control rod and the maximum insertion limit thereof; determining the time of insertion of the control rod by simulating core combustion by reflecting the duration of insertion of the control rod in a nuclear design code at each of a plurality of time points of the corresponding cycle; and producing a nuclear design core model accounting for load following on the basis of the determined amount of insertion of the control rod, the determined duration of insertion of the control rod, and the determined time of insertion of the control rod.

Description

Production method of nuclear design core model considering load following

[0001] The present invention relates to a method for producing a nuclear design core model considering load following.

[0002] The nuclear design core model used to produce nuclear design data and safety analysis linkage data in the current design is based on a state where full power and full control rods are withdrawn.

[0003] For this reason, in order to apply load-following operation to nuclear power plants, a nuclear design core model that reflects the partial power / control rod insertion state is essential.

[0004] To produce a load-following operation nuclear design core model and nuclear design data, the entire load-following operation history must be reflected throughout the entire cycle before performing burnup calculations. This is a challenging and time-consuming task. Therefore, a simple load-following operation burnup model is needed that effectively reflects the core power distribution changes that can occur during load-following operation while allowing for the simplest possible input of load-following operation history.

[0005] Accordingly, the purpose of the present invention is to provide a method for producing a nuclear design core model that takes load following into account.

[0006] The above object of the present invention is achieved by a method for producing a nuclear design core model considering load following, comprising: a step of receiving a load following requirement for a corresponding cycle, wherein the load following requirement includes at least one of a power reduction amount, a number of load following operations, an operation time of reduced power, and an operation period; a step of determining a control rod insertion amount based on the load following requirement; a step of determining a control rod insertion period based on the control rod insertion amount and a maximum insertion limit; a step of determining a control rod insertion point by simulating core combustion by reflecting the control rod insertion period in a nuclear design code for each of a plurality of time points in the corresponding cycle; and a step of producing a nuclear design core model considering load following based on the determined control rod insertion amount, control rod insertion period, and control rod insertion point.

[0007] In determining the insertion amount of the control rod, a core analysis code is used for each burnup degree to determine an insertion position at which the output and axial output deviation are maintained within an allowable setting value at the time of insertion of the control rod, and the insertion amount of the control rod can be determined by the sum of the products between the insertion position and the burnup degree.

[0008] The insertion period of the above control rod can be determined by dividing the insertion amount of the above control rod by the maximum insertion limit.

[0009] The multiple points in time in determining the control rod insertion point may include the beginning of the cycle, the middle of the cycle, and the end of the cycle.

[0010] In determining the above control rod insertion point, a sensitivity evaluation of the accident analysis linked variables is performed, and the point in time that produces the most conservative linked variables among multiple points in time can be determined as the control rod insertion point.

[0011] The above control rod includes a regulating control rod and a partial reinforcement control rod, and the insertion amount of the control rod, the insertion period of the control rod, and the insertion point of the control rod can be determined for each of the regulating control rod and the partial reinforcement control rod.

[0012] According to the present invention, a method for producing a nuclear design core model considering load following is provided.

[0013] Figure 1 is a flowchart of a method for producing a nuclear design core model considering load following according to one embodiment of the present invention.

[0014] The present invention will be described in more detail with reference to the drawings below.

[0015] The attached drawings are merely examples intended to more specifically illustrate the technical concepts of the present invention, and therefore, the scope of the present invention is not limited to the attached drawings. Furthermore, the attached drawings may exaggerate the size and spacing of components to illustrate the relationships between components.

[0016] Previously, nuclear design parameters were generated using a core analysis model with all control rods withdrawn at 100% power. Therefore, it is necessary to create a core analysis model with the control rods inserted, which account for the power output changes during frequent power reduction operations (load-following operation), and to generate nuclear design parameters based on this model.

[0017] The present invention relates to a method for producing a core analysis model for producing nuclear design-related variables by reflecting the influence of control rods within the core when reduced power operation of a nuclear power plant is required by a power exchange, etc., unlike the existing full (100%) power operation.

[0018] Referring to FIG. 1 below, a method for producing a nuclear design core model considering load following according to an embodiment of the present invention is described.

[0019] First, the load following requirements for the corresponding cycle are input (S100).

[0020] Here, the load following requirement includes at least one of the amount of output reduction, the number of load following operations, the operating time of reduced output, and the operating period.

[0021] A core analysis model considering load following must be produced every cycle (1-2 years). Therefore, prior to the start of each cycle, prior consultation (decision) is required with the power exchange (power system operator) regarding load following requirements, such as the maximum required output reduction amount (30, 40, 50% output, etc.) for the nuclear power plant, the expected number of output reductions (# / year), and the reduced output maintenance time (hours). In this invention, based on the derived load following requirements, a core analysis model is produced, which serves as the basis for generating core-linked variables used as input for the safety analysis of nuclear power plants.

[0022] Next, the insertion amount of the control rod is determined based on the load following requirement (S200).

[0023] In determining the insertion amount of the control rod, the core analysis code is used for each burnup to determine the insertion position at which the output and axial output deviation at the time of power reduction are maintained within the allowable set value. The insertion amount of the control rod can be determined by the sum of the products between the insertion position (i.e., the control rod insertion length) and the burnup, as follows.

[0024] Control rod insertion amount = Σ (control rod insertion length * combustion degree)

[0025] The insertion amount can be determined as the control rod insertion position (amount) that maintains the optimal axial output deviation after performing a load following operation simulation calculation using a core analysis code to ensure that the output and axial output deviation (ASI) are well maintained within the allowable setting value at the determined insertion point.

[0026] Afterwards, the insertion period of the control rod is determined based on the insertion amount and maximum insertion limit of the control rod (S300).

[0027] The control rod insertion period is the period during which the control rod must be inserted into the core for a certain period of time (e.g., one year).

[0028] The control rod insertion period is determined by dividing the control rod insertion amount by the maximum insertion limit. The maximum insertion limit is determined by core type and may vary depending on the core type.

[0029] That is, if the control rod insertion amount of the regulating control group is operated by inserting up to 28% of the maximum insertion limit (e.g., 194250), the insertion period of the control rod of the regulating control group becomes 7700 MWD / MTU (194250 / 28). The partial control rod is calculated in the same way.

[0030] Next, for each multiple point in time of the cycle, the control rod insertion period is reflected in the nuclear design code to simulate core combustion and determine the control rod insertion point (S400).

[0031] Multiple points in time in determining the control rod insertion point include the beginning of the cycle, the middle of the cycle, and the end of the cycle.

[0032] When determining the control rod insertion point, a sensitivity assessment of the accident analysis associated variables is performed, and the point that produces the most conservative associated variables among multiple points in time can be selected as the control rod insertion point. Here, a "conservative associated variable" refers to an associated variable (accident analysis input data) that worsens the accident analysis (safety analysis) results. Typically, the end-of-cycle event is expected to produce conservative associated variables.

[0033] In the steps described above, the control rod includes a regulating control rod and a partial reinforcement control rod, and the insertion amount of the control rod, the insertion period of the control rod, and the insertion point of the control rod can be determined for each of the regulating control rod and the partial reinforcement control rod.

[0034] Finally, a nuclear design core model considering load following is produced based on the determined control rod insertion amount, control rod insertion period, and control rod insertion point (S500).

[0035] Nuclear design is the process of producing linked variables that serve as inputs for safety analysis / accident analysis. The fundamental model required for nuclear design is the nuclear design core model. The "nuclear design core model" according to the present invention refers to a fundamental core model required for nuclear design that takes load tracking into account.

[0036] The nuclear design core model produced according to the present invention is a simple core model production method applicable to load-following operation with various operating histories, and can contribute to reducing future core design costs and obtaining approvals in a conservative manner.

[0037] The above-described examples serve as illustrative examples of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate the potential for various modifications and implementations of the present invention. Therefore, the technical scope of the present invention should be defined by the appended claims.

Claims

1. In the production method of a nuclear design core model considering load following, A step of receiving a load following requirement for a corresponding cycle, wherein the load following requirement includes at least one of an output reduction amount, a number of load following operations, an operation time of reduced output, and an operation period; A step of determining the insertion amount of the control rod based on the above load following requirements; A step of determining the insertion period of the control rod based on the insertion amount and maximum insertion limit of the control rod; A step of determining the control rod insertion point by simulating core combustion by reflecting the insertion period of the control rod in the nuclear design code at multiple points in time during the above cycle; and A method comprising a step of producing a nuclear design core model considering load following based on the determined control rod insertion amount, control rod insertion period, and control rod insertion point.

2. In paragraph 1, In determining the insertion amount of the above control rod, the core analysis code is used for each combustion degree to determine the insertion position at which the output and axial output deviation are maintained within the allowable setting value at the time of insertion of the control rod. A method in which the insertion amount of the above control rod is determined by the sum of the products between the insertion position and the combustion degree.

3. In paragraph 2, A method of determining the insertion period of the control rod by dividing the insertion amount of the control rod by the maximum insertion limit.

4. In paragraph 1, A method in which multiple points in time in determining the control rod insertion point include the beginning of the cycle, the middle of the cycle, and the end of the cycle.

5. In paragraph 4, In determining the above control rod insertion point, a method of performing a sensitivity evaluation of accident analysis linked variables and determining the point in time that produces the most conservative linked variable among multiple points in time as the control rod insertion point.

6. In paragraph 1, The above control rod includes a regulating control rod and a partial strength control rod, A method in which the insertion amount of the control rod, the insertion period of the control rod, and the insertion point of the control rod are determined separately for the regulating control rod and the partial strengthening control rod.

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