Calculation method and calculation device for measuring control rod value through nuclear power plant rod falling method

Abstract

The invention relates to the technical field of nuclear power plant safety testing, in particular to a calculation method and a calculation device for measuring control rod value through a nuclear power plant rod falling method. Comprising the following steps: acquiring an initial moment t0 and a neutron-flux density n0 corresponding to the initial moment t0 of a to-be-tested control rod before rod falling, a moment t1 when rod falling is finished and a neutron-flux density n1 corresponding to the moment t1 when rod falling is finished, and any moment t2 after rod falling is finished and a neutron-flux density n2 corresponding to the any moment t2; calculating the period T1 of the moment after rod falling; obtaining the average generation time lambda of instant neutrons and the total effective share beta eff of delayed neutrons in all fission neutrons; and calculating the value of the to-be-tested control rod. Compared with a traditional method, the method has the advantages that the influence of the prompt neutrons is considered, the starting point of a progressive value does not need to be manually judged, after the influence factor # imgabs0 # of the prompt neutrons is introduced, waiting for the neutron flux to approach the progressive value is not needed, and a wider data point selection range can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power plant safety testing, and in particular to a calculation method and a calculation device for measuring the value of control rods by a rod drop method in a nuclear power plant. Background Art

[0002] The total value of the reactor control rods is directly related to the shutdown margin of the reactor. The rod drop method measures the control rod value by obtaining the actual measured data of the rod drop shutdown through the power plant computer real-time data acquisition system, and then uses the offline digital reactivity instrument program to calculate the rod drop value. The traditional rod drop method has two assumptions. One is that the density of delayed neutron precursor nuclei remains basically unchanged in this extremely short period of time before and after the rod drop. The other is that the power level changes rapidly to its asymptotic value after the rod drop, that is, it is assumed that The advantage of the traditional falling rod method is its simplicity, as shown in the following formula (1). However, its disadvantage is that the second assumption does not take into account the influence of prompt neutrons, and requires manual judgment of the starting point of an asymptotic value, which will introduce measurement errors.

[0003] Summary of the invention

[0004] The purpose of the present invention is to propose a calculation method and a calculation device for measuring the value of control rods by the rod drop method in a nuclear power plant, which is used to solve the technical problem that the traditional method assumes that the influence of prompt neutrons is not considered and requires manual judgment of the starting point of an asymptotic value.

[0005] The technical solution of the present invention:

[0006] The first aspect of the present invention provides a method for calculating the value of control rods measured by the rod drop method in a nuclear power plant, the method comprising the following steps:

[0007] Obtain the initial time t0 before the rod drop begins and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, and the arbitrary time t2 after the rod drop ends and the neutron flux density n2 corresponding to the arbitrary time t2. According to the time t1 when the rod drop ends, the neutron flux density n1 corresponding to the time t1 when the rod drop ends, the arbitrary time t2, and the neutron flux density n2 corresponding to the arbitrary time t2, and in combination with formula (2), calculate the period T1 after the rod drop.

[0008]

[0009] Obtain the average generation time of prompt neutrons Λ and the total effective share of delayed neutrons in all fission neutrons β eff .

[0010] According to the neutron flux density n0 corresponding to the initial time t0, the average generation time Λ of prompt neutrons, and the total effective share β of delayed neutrons in all fission neutrons eff , and the period T1 after the rod is dropped, and the value of the control rod to be tested |ρ1| is calculated by combining formula (3).

[0011]

[0012] The initial time t0 of the control rod to be tested before the rod drop starts and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, and any time t2 after the rod drop ends and the neutron flux density n2 corresponding to the any time t2 are obtained, including: before the rod drop test starts, confirming that the core is in a critical state; recording the initial time t0 of the control rod to be tested before the rod drop starts and the neutron flux density n0 corresponding to the initial time t0 measured by an out-of-core nuclear instrument; at the beginning of the rod drop test, inserting the control rod to be tested to the bottom of the reactor; after the rod drop test ends, recording the neutron flux density n1 corresponding to the time t1 when the rod drop ends and the time t1 when the rod drop ends measured by an out-of-core nuclear instrument, and any time t2 after the rod drop ends and the neutron flux density n2 corresponding to the any time t2 measured by an out-of-core nuclear instrument.

[0013] The difference between the time t1 when the rod drops to the end and the initial time t0 is less than or equal to 1 s.

[0014] The second aspect of the present invention provides a calculation device for measuring the value of control rods in a nuclear power plant by the rod drop method, the calculation device comprising an acquisition module and a calculation module. The acquisition module is used to obtain the initial time t0 before the rod drop begins and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, any time t2 after the rod drop ends and the neutron flux density n2 corresponding to any time t2, the average generation time Λ of prompt neutrons and the total effective share β of delayed neutrons in all fission neutrons eff .

[0015] The calculation module is used to calculate the period T1 after the rod drop according to the time t1 when the rod drop ends, the neutron flux density n1 corresponding to the time t1 when the rod drop ends, any time t2, and the neutron flux density n2 corresponding to any time t2, and in combination with formula (2).

[0016]

[0017] According to the neutron flux density n0 corresponding to the initial time t0, the average generation time Λ of prompt neutrons, and the total effective share β of delayed neutrons in all fission neutrons eff, and the period T1 after the rod is dropped, and the value of the control rod to be tested |ρ1| is calculated by combining formula (3).

[0018]

[0019] A third aspect of the present invention provides a computer-readable storage medium having computer executable instructions stored thereon, which, when executed by a processor, implements a method for calculating the value of control rods measured by the rod drop method in a nuclear power plant.

[0020] The fourth aspect of the present invention provides an electronic device, which is characterized by comprising a processor and a memory. The processor is used to execute the calculation method for measuring the value of control rods by the rod drop method in a nuclear power plant; and the memory is used to store executable instructions of the processor.

[0021] Beneficial effects of the present invention:

[0022] The present invention proposes a calculation method and device for measuring the value of control rods by the rod drop method in a nuclear power plant. Compared with the traditional method, the method takes into account the influence of prompt neutrons, does not require manual judgment of the starting point of an asymptotic value, and introduces the influence factor of prompt neutrons. After that, there is no need to wait for the neutron flux to approach the asymptotic value, and a wider range of data points can be selected. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a method for calculating the value of control rods in a nuclear power plant using the rod drop method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is clearly and completely described below in conjunction with specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0025] like Figure 1 At least one embodiment of the present invention provides a calculation method for measuring the value of control rods in a nuclear power plant by a rod drop method, and the execution subject of the calculation method can be a processor or a server, etc. The calculation method includes the following steps.

[0026] S1: Obtain the initial time t0 of the control rod to be tested before the rod drop begins and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, and any time t2 after the rod drop ends and the neutron flux density n2 corresponding to any time t2.

[0027] S1.1: Before the rod drop test begins, confirm that the core is in a critical state.

[0028] S1.2: Record the initial time t0 of the control rod to be tested before the rod drop begins, and the neutron flux density n0 corresponding to the initial time t0 measured by the out-of-core nuclear instrument.

[0029] S1.3: At the beginning of the rod drop test, insert the control rod to be tested to the bottom of the pile.

[0030] S1.4: After the rod drop test is completed, record the neutron flux density n1 corresponding to the time t1 at which the control rod to be tested is dropped and the time t1 at which the rod drop is completed measured by the out-of-core nuclear instrument, as well as the neutron flux density n2 corresponding to any time t2 after the rod drop is completed and any time t2 at which the rod drop is completed measured by the out-of-core nuclear instrument.

[0031] S2: Based on the time t1 when the rod is dropped, the neutron flux density n1 corresponding to the time t1 when the rod is dropped, any time t2, and the neutron flux density n2 corresponding to any time t2, and combined with formula (2), calculate the period T1 after the rod is dropped.

[0032]

[0033] S3: Obtain the average generation time of prompt neutrons Λ and the total effective share of delayed neutrons in all fission neutrons β eff .

[0034] S4: According to the neutron flux density n0 corresponding to the initial time t0, the average generation time of prompt neutrons Λ, and the total effective share of delayed neutrons in all fission neutrons β eff , and the period T1 after the rod is dropped, and the value of the control rod to be tested |ρ1| is calculated by combining formula (3).

[0035]

[0036] This calculation method is applicable to the calculation when the difference between the time t1 when the rod drops to the end and the initial time t0 is less than or equal to 1s.

[0037] At least one embodiment of the present invention also provides a calculation device for measuring the value of control rods in a nuclear power plant by the rod drop method, the calculation device comprising an acquisition module and a calculation module. The acquisition module is used to obtain the initial time t0 before the rod drop begins and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, any time t2 after the rod drop ends and the neutron flux density n2 corresponding to any time t2, the average generation time Λ of prompt neutrons and the total effective share β of delayed neutrons in all fission neutrons effThe calculation module is used to calculate the period T1 after the rod drop according to the time t1 when the rod drop ends, the neutron flux density n1 corresponding to the time t1 when the rod drop ends, any time t2, and the neutron flux density n2 corresponding to any time t2, and in combination with formula (2).

[0038]

[0039] According to the neutron flux density n0 corresponding to the initial time t0, the average generation time Λ of prompt neutrons, and the total effective share β of delayed neutrons in all fission neutrons eff , and the period T1 after the rod is dropped, and the value of the control rod to be tested |ρ1| is calculated by combining formula (3).

[0040]

[0041] The calculation device is a calculation device corresponding to the calculation method for measuring the value of control rods in a nuclear power plant by the rod drop method provided in the above-mentioned embodiment of the present application, and therefore can at least achieve the above-mentioned corresponding technical effects, which will not be repeated here.

[0042] At least one embodiment of the present invention also provides an electronic device, which includes a processor and a memory. The memory is used to store instructions that can be executed by the processor, such as an application. The number of processors can be one or more. The application stored in the memory can include one or more modules, each corresponding to a set of instructions. In addition, the processor is configured to execute instructions to execute the above-mentioned method for calculating the value of control rods measured by the rod drop method in a nuclear power plant.

[0043] The electronic device may also include a power supply component configured to manage power of the electronic device, a wired or wireless network interface configured to connect the electronic device to a network, and an input / output (I / O) interface. The electronic device may operate based on an operating system stored in the memory, such as Windows ServerTM, Mac OSXTM, UnixTM, LinuxTM, FreeBSDTM or the like.

[0044] A computer-readable storage medium is provided in one embodiment of the present application. When the instructions in the storage medium are executed by the processor of the electronic device, the electronic device can execute a method for calculating the value of control rods measured by the rod-drop method in a nuclear power plant. The calculation method is executed by an agent program, and the calculation method includes: obtaining the initial time t0 of the control rod to be tested before the rod drop begins and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, and any time t2 after the rod drop ends and the neutron flux density n2 corresponding to any time t2. According to the time t1 when the rod drop ends, the neutron flux density n1 corresponding to the time t1 when the rod drop ends, any time t2, and the neutron flux density n2 corresponding to any time t2, and in combination with formula (2), calculate the period T1 of the time after the rod drop.

[0045]

[0046] Obtain the average generation time of prompt neutrons Λ and the total effective share of delayed neutrons in all fission neutrons β eff According to the neutron flux density n0 corresponding to the initial time t0, the average generation time of prompt neutrons Λ, and the total effective share of delayed neutrons in all fission neutrons β eff , and the period T1 after the rod is dropped, combined with formula (3) to calculate the value of the control rod to be tested |ρ1|.

[0047]

[0048] Those of ordinary skill in the art will appreciate that the algorithmic steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0049] In the several embodiments provided in this application, it should be understood that the disclosed computing methods and computing devices can be implemented in other ways. For example, the computing device embodiments described above are only schematic, for example, the division of modules is only a logical function division, and there may be other division methods in actual implementation, for example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed.

[0050] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the calculation method of each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program check codes.

[0051] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the computing device and the electronic device described above can refer to the corresponding processes in the aforementioned computing method embodiments, and will not be repeated here.

[0052] In order to understand the present invention more clearly, the inventive concept of the present invention is explained. According to the principle of the drop rod method, according to the neutron flux density n0 before the drop rod; the neutron flux density n1 after the drop rod; the reactivity ρ0 before the drop rod; the reactivity ρ1 after the drop rod; the total effective share β of delayed neutrons in all fission neutrons eff ; Average generation time of prompt neutrons Λ; Precursor concentration of delayed neutrons in group i at time t C i (t); the intensity of the external neutron source q; the decay constant λ of the i-th group of delayed neutron precursor nuclear fission fragments i ; After the rod drop, the reactor cycle is T1, and the neutron kinetic equation before the rod drop is described as formula (4).

[0053]

[0054] The neutron kinetic equation of the drop-rod post-point reactor is described as equation (5).

[0055]

[0056] Assuming that the density of delayed neutron precursor nuclei remains basically unchanged in this extremely short time after the rod is dropped, the above two equations become equation (6).

[0057]

[0058] The formula for rapid rod drop is obtained as formula (7).

[0059]

[0060] In the above formula (7), If the rod is in a critical state before it falls, that is, ρ0=0, Then the above formula becomes formula (8).

[0061]

[0062] Compared with the traditional method, the present invention takes into account the influence of prompt neutrons, does not need to manually determine the starting point of an asymptotic value, and introduces the influence factor of prompt neutrons. After that, there is no need to wait for the neutron flux to approach the asymptotic value, and a wider range of data points can be selected.

[0063] In order to verify the accuracy of the improved formula, a comparative explanation is given. The reactor is initially in a critical state, assuming that the rod drop time is extremely short, reaching 1E-4s, the rod drop value is 1000pcm, and the delayed neutron data are shown in Table 1.

[0064] Table 1 Delayed neutron data

[0065]

[0066] Table 2 shows a comparison of the reactivity of the present invention and the conventional technology when measuring the rod drop.

[0067] Table 2 Comparison of reactivity results after instantaneous rod drop

[0068]

[0069] It can be seen from Table 2 that compared with the traditional method, the optimized falling rod method takes into account the influence of prompt neutron changes and introduces the influence factor of prompt neutrons. After that, there is no need to wait for the neutron flux to approach the asymptotic value, and a wider range of data points can be selected. It should be noted that the traditional method and this calculation method have relatively high requirements for the time of data processing selection. It can be seen from Table 2 that when the selection time reaches 1s, the reactivity errors measured by the two methods are relatively large. This is because when the time reaches the second level, the influence of delayed neutrons cannot be ignored.

[0070] Taking t0=0, t1=0.0001, t2=0.0002 as an example, the reactivity is calculated as follows.

[0071] The optimized falling rod method formula is: Where Λ, λ i , β ieff and β eff These are all neutronic parameters, which are considered constants during the experiment and can be calculated from theoretical data. Here, we take the data in Table 1, and Λ is 2×10-5s.

[0072] Before the test begins, confirm that the core is in a critical state. At the beginning of the test, the control rod to be tested is inserted to the bottom of the reactor. Before the rod drop begins, t0=0, and the corresponding out-of-core instrument signal value is recorded as n0=1; according to the rod drop time, the rod drop end time is determined as t1=0.0001, and the corresponding out-of-core instrument signal value is recorded as n1=0.980278; select any time after the rod drop ends, and take t2=0.0002 for convenience of example, and record the corresponding out-of-core instrument signal value as n2=0.93357. Among them, t0 and t1 are determined according to the actual rod drop time, and t2 can be any time point after the rod drop ends. t2 is taken to calculate the period T1 after the rod drop. The period T1 is calculated by formula (2) as follows.

[0073]

[0074] Substituting the above values ​​and the delayed neutron parameter into formula (3), the reactivity after the rod drop can be obtained:

[0075]

[0076] Then the value of the control rod to be tested is |ρ1|=1050.4pcm.

[0077] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for calculating the value of control rods in a nuclear power plant by the rod drop method, characterized in that: The method comprises the following steps: Obtaining an initial time t0 before the rod drop starts and a neutron flux density n0 corresponding to the initial time t0, a time t1 when the rod drop ends and a neutron flux density n1 corresponding to the time t1 when the rod drop ends, and an arbitrary time t2 after the rod drop ends and a neutron flux density n2 corresponding to the arbitrary time t2; According to the time t1 when the rod drop ends, the neutron flux density n1 corresponding to the time t1 when the rod drop ends, the arbitrary time t2, and the neutron flux density n2 corresponding to the arbitrary time t2, and in combination with formula (1), the period T1 after the rod drop is calculated. Obtain the average generation time of prompt neutrons Λ and the total effective share of delayed neutrons in all fission neutrons β eff ; According to the neutron flux density n0 corresponding to the initial time t0, the average generation time Λ of the prompt neutrons, the total effective fraction β of the delayed neutrons in all fission neutrons eff , and the period T1 after the rod is dropped, and the value |ρ1| of the control rod to be tested is calculated by combining formula (2).

2. The calculation method according to claim 1, characterized in that: The obtaining of the initial time t0 of the control rod to be tested before the rod dropping starts and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod dropping ends and the neutron flux density n1 corresponding to the time t1 when the rod dropping ends, and any time t2 after the rod dropping ends and the neutron flux density n2 corresponding to the any time t2 comprises: Before the rod drop test begins, confirm that the core is in a critical state; Recording the initial time t0 of the control rod to be tested before the rod drop begins, and the neutron flux density n0 corresponding to the initial time t0 measured by an out-of-core nuclear instrument; At the beginning of the rod drop test, the control rod to be tested is inserted down to the bottom of the pile; After the rod drop test is completed, the neutron flux density n1 corresponding to the time t1 at which the control rod to be tested is dropped and the time t1 at which the rod drop is completed measured by the out-of-core nuclear instrument, as well as the neutron flux density n2 corresponding to any time t2 after the rod drop is completed and the time t2 at which the rod drop is completed measured by the out-of-core nuclear instrument are recorded.

3. The calculation method according to claim 1, characterized in that: The difference between the time t1 when the rod drops are finished and the initial time t0 is less than or equal to 1 second.

4. A calculation device for measuring the value of control rods by the rod drop method in a nuclear power plant, characterized in that: include: an acquisition module, for acquiring the initial time t0 of the control rod to be tested before the rod drop begins and the neutron flux density n0 corresponding to the initial time t0, the time t1 when the rod drop ends and the neutron flux density n1 corresponding to the time t1 when the rod drop ends, any time t2 after the rod drop ends and the neutron flux density n2 corresponding to the any time t2, the average generation time Λ of prompt neutrons, and the total effective fraction β of delayed neutrons in all fission neutrons eff ; a calculation module, for calculating the period T1 after the rod drop according to the time t1 at which the rod drop ends, the neutron flux density n1 corresponding to the time t1 at which the rod drop ends, the arbitrary time t2, and the neutron flux density n2 corresponding to the arbitrary time t2, and in combination with formula (1), According to the neutron flux density n0 corresponding to the initial time t0, the average generation time Λ of the prompt neutrons, the total effective share β of the delayed neutrons in all fission neutrons eff , and the period T1 after the rod is dropped, and the value |ρ1| of the control rod to be tested is calculated by combining formula (2).

5. A computer-readable storage medium having computer executable instructions stored thereon, characterized in that: When the executable instructions are executed by the processor, the method for calculating the value of control rods in a nuclear power plant using the rod drop method as described in any one of claims 1 to 3 is implemented.

6. An electronic device, characterized in that: include: A processor, configured to execute the calculation method for measuring the value of control rods by the rod drop method in a nuclear power plant according to any one of claims 1 to 3; and a memory for storing executable instructions of the processor.

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