Method and device for calculating value of control rod by drop rod method, and electronic device

Abstract

The application relates to the technical field of nuclear power plant safety testing, and particularly relates to a method for calculating the value of a control rod by a falling rod method and a device and an electronic device thereof, which comprises the following steps: acquiring the initial time t0 of a to-be-tested control rod before falling rod starts, the neutron flux density n0 corresponding to the initial time t0, the time t1 of falling rod ending, the neutron flux density n1 corresponding to the time t1, and the second neutron flux density n2 corresponding to any time t2 after the falling rod ends; calculating the period T1 of the time after the falling rod; and calculating the value |p1| of the to-be-tested control rod. In the application, the optimized formula simultaneously considers the influence of prompt neutrons and delayed neutrons, so that the measurement error of the falling rod method can be significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant safety testing technology, specifically relating to a method, apparatus, and electronic equipment for calculating the value of control rods using the drop rod method. Background Technology

[0002] The total value of reactor control rods directly relates to the reactor's shutdown margin. The drop rod method measures the control rod value by acquiring measured data from the actual shutdown process using a real-time data acquisition system on the power plant's computer, and then calculating the value using an offline digital reactivity analyzer program. Under the assumption of a very short timeframe, the traditional drop rod method generally does not consider the contribution of delayed neutrons. However, the drop rod time in typical reactors is on the order of seconds, and two sets of delayed neutron precursor nuclei have half-lives of less than one second. Therefore, neglecting the influence of delayed neutrons will lead to a significant calculation error in the drop rod method. Summary of the Invention

[0003] The purpose of this invention is to propose a method, apparatus, and electronic device for calculating the value of control rods using the drop rod method, which solves the technical problem of large calculation errors caused by the traditional drop rod method in calculating the value of control rods due to the lack of consideration for the contribution of delayed neutrons.

[0004] The first aspect of this invention provides a method for calculating the value of a control rod using the drop rod method, the method comprising:

[0005] The test control rod is obtained at the initial time t0 before the start of the drop and the neutron flux density n0 corresponding to the initial time t0, the drop end time t1 and the neutron flux density n1 corresponding to the drop end time t1, and any time t2 after the drop end and the neutron flux density n2 corresponding to any time t2.

[0006] Based on the time t1 at which the rod falls, the neutron flux density n1 corresponding to the time t1, any time t2, and the neutron flux density n2 corresponding to any time t2, and combined with formula (1), the period T1 after the rod falls is calculated.

[0007]

[0008] Obtain the average generation time Λ of instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The total effective share β of moderately emitted neutrons in all fission neutrons eff The time interval Δt before and after the drop bar;

[0009] Based on the neutron flux density n0 at the initial time t0, the mean generation time Λ of instantaneous neutrons, and the total effective share β of delayed neutrons in all fission neutrons.eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective share β of the i-th delayed neutron in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i Combined with formula (2), the value of the control rod under test, |ρ1|, is calculated.

[0010]

[0011] In at least one embodiment of the present invention, obtaining the initial time t0 and the neutron flux density n0 corresponding to the control rod under test before the start of the drop test, the end time t1 and the neutron flux density n1 corresponding to the end time t1 after the drop test, and any time t2 and the neutron flux density n2 corresponding to the end time t2 after the drop test, includes: before the start of the drop test, confirming that the reactor core is in a critical state; recording the initial time t0 of the control rod under test before the start of the drop test, and the neutron flux density n0 corresponding to the initial time t0 measured by an external nuclear instrument; at the start of the drop test, inserting the control rod under test to the bottom of the reactor; after the drop test, recording the neutron flux density n1 corresponding to the end time t1 of the drop test and the neutron flux density n2 corresponding to the end time t1 measured by an external nuclear instrument, and any time t2 and the neutron flux density n2 corresponding to the end time t2 after the drop test.

[0012] A second aspect of the present invention provides an apparatus for calculating the value of a control rod using the drop rod method, the apparatus comprising an acquisition module and a calculation module.

[0013] The acquisition module is used to acquire the initial time t0 before the start of the test control rod drop and the corresponding neutron flux density n0, the end time t1 before the start of the drop and the corresponding neutron flux density n1, and any time t2 after the end of the drop and the corresponding neutron flux density n2. It also acquires the average generation time Λ of the instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The total effective share β of moderately emitted neutrons in all fission neutrons eff .

[0014] The calculation module is used to calculate the period T1 after the rod falls, based on the time t1 at the end of the rod fall, the neutron flux density n1 corresponding to the time t1 at the end of the rod fall, any time t2, and the neutron flux density n2 corresponding to any time t2, and in combination with formula (1).

[0015]

[0016] And based on the neutron flux density n0 at the initial time t0, the mean generation time Λ of the instantaneous neutrons, and the total effective share β of the delayed neutrons in all fission neutrons. eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective share β of the i-th delayed neutron in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i Combined with formula (2), the value of the control rod under test, |ρ1|, is calculated.

[0017]

[0018] A third aspect of the present invention provides a computer-readable storage medium having stored executable instructions of a computer thereon, which, when executed by a processor, implement a method for calculating the value of a control rod using a drop bar method according to the first aspect of the present invention.

[0019] A fourth aspect of the present invention provides an electronic device comprising a processor and a memory. The processor is used to execute a method for calculating the value of a control rod using a drop bar method according to a first aspect of the present invention; the memory is used to store executable instructions of the processor.

[0020] The beneficial effects of this invention are:

[0021] Compared to traditional methods for calculating the value of control rods, the optimized drop rod method takes into account the effects of both instantaneous and delayed neutrons, thus significantly reducing the calculation error of the drop rod method. Attached Figure Description

[0022] Figure 1 A flowchart illustrating a method for calculating the value of a control rod using the drop bar method, provided as an embodiment of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0024] like Figure 1 At least one embodiment of the present invention provides a method for calculating the value of a control rod using the drop rod method. The method can be executed by a processor or server, etc. The method includes the following steps:

[0025] S1: Obtain the initial time t0 before the start of the test control rod drop and the neutron flux density n0 corresponding to the initial time t0, the end time t1 before the start of the drop and the neutron flux density n1 corresponding to the end time t1, and any time t2 after the end of the drop and the neutron flux density n2 corresponding to any time t2.

[0026] In at least one embodiment of the present invention, steps S1.1 to S1.4 are specific implementations of step S1.

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

[0028] S1.2: Record the initial time t0 of the control rod under test before the rod drops begin, and the neutron flux density n0 corresponding to the initial time t0 measured by the external nuclear instrument.

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

[0030] S1.4: After the drop test, record the neutron flux density n1 corresponding to the control rod at the end of the drop test at time t1 and the end of the drop test at time t1 measured by the external nuclear instrument, as well as the neutron flux density n2 corresponding to any time t2 after the drop test and any time t2 measured by the external nuclear instrument.

[0031] S2: Based on the time t1 when the rod falls, the neutron flux density n1 corresponding to the time t1 when the rod falls, any time t2, and the neutron flux density n2 corresponding to any time t2, and combined with formula (1), calculate the period T1 after the rod falls.

[0032]

[0033] S3: Obtain the average generation time Λ of the instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The total effective share β of delayed-emission neutrons among all fission neutrons eff The time interval Δt before and after the drop bar.

[0034] S4: Based on the neutron flux density n0 at the initial time t0, the mean generation time Λ of instantaneous neutrons, and the total effective share β of delayed neutrons in all fission neutrons. eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective share β of the i-th delayed neutron in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The value of the control rod to be tested, |ρ1|, is calculated using formula (2).

[0035]

[0036] At least one embodiment of the present invention also provides an apparatus for calculating the value of a control rod using the drop rod method. The apparatus includes an acquisition module and a calculation module. The acquisition module is used to acquire the initial time t0 before the start of the drop rod and the neutron flux density n0 corresponding to the initial time t0, the end time t1 before the drop rod starts and the neutron flux density n1 corresponding to the end time t1, and any time t2 after the drop rod ends and the neutron flux density n2 corresponding to any time t2; and to acquire the average generation time Λ of the instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The time interval Δt before and after the rod falls, and the decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments. i The total effective share β of moderately emitted neutrons in all fission neutrons eff The calculation module is used to calculate the period T1 after the rod falls, based on the end time t1, the neutron flux density n1 corresponding to the end time t1, any time t2, and the neutron flux density n2 corresponding to any time t2, and in combination with formula (1).

[0037]

[0038] And based on the neutron flux density n0 at the initial time t0, the mean generation time Λ of the instantaneous neutrons, and the total effective share β of the delayed neutrons in all fission neutrons. eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective share β of the i-th delayed neutron in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i Combined with formula (2), the value of the control rod under test, |ρ1|, is calculated.

[0039]

[0040] This computing device corresponds to the device for the method of measuring the value of control rods in a nuclear power plant using the drop rod method provided in the above embodiments of the present invention. Therefore, it can at least achieve the above-mentioned corresponding technical effects, which will not be elaborated here.

[0041] At least one embodiment of the present invention also provides an electronic device including a processor and a memory. The memory stores instructions executable by the processor, such as application programs. The number of processors can be one or more. The application programs stored in the memory can include one or more modules, each corresponding to a set of instructions. Furthermore, the processor is configured to execute instructions to perform the method described above for calculating the value of a control stick using the drop bar method. The electronic device may also include a power supply component configured for power management 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 can operate on an operating system stored in the memory, such as Windows Server™, Mac OSX™, Unix™, Linux™, FreeBSD™, or similar.

[0042] At least one embodiment of the present invention also provides a computer-readable storage medium, which, when the instructions in the storage medium are executed by the processor of the electronic device, enables the electronic device to perform a method for calculating the value of a control rod using a drop rod method. This method is executed by an agent program and includes obtaining the initial time t0 before the start of the drop rod and the neutron flux density n0 corresponding to the initial time t0, the end time t1 of the drop rod and the neutron flux density n1 corresponding to the end time t1, and any time t2 after the end of the drop rod and the neutron flux density n2 corresponding to any time t2; calculating the period T1 after the drop rod using the end time t1, the neutron flux density n1 corresponding to the end time t1, the arbitrary time t2, and the neutron flux density n2 corresponding to any time t2, and in conjunction with formula (1).

[0043]

[0044] Obtain the average generation time Λ of instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The total effective share β of moderately emitted neutrons in all fission neutrons eff The time interval Δt before and after the rod falls; based on the neutron flux density n0 corresponding to the initial time t0, the mean generation time Λ of the instantaneous neutrons, and the total effective share β of the delayed neutrons in all fission neutrons. eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective share β of the i-th delayed neutron in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The value of the control rod to be tested, |ρ1|, is calculated using formula (2).

[0045]

[0046] Those skilled in the art will recognize that the algorithmic steps of the various examples described in conjunction with the embodiments disclosed in this invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0047] In the several embodiments provided by this invention, it should be understood that the disclosed methods and apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed.

[0048] If a function is implemented as 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 this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program verification codes, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0049] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the computing devices and electronic devices described above can be referred to the corresponding processes in the foregoing computing method embodiments, and will not be repeated here.

[0050] To better understand this invention, the inventive concept is explained below. The derivation, corresponding to the drop rod method principle and considering the influence of delayed neutrons, is as follows: Based on the neutron density n0 before drop rod drop; the neutron density n1 after drop rod drop; the reactivity ρ0 before drop rod drop; the reactivity ρ1 after drop rod drop; and the effective share β of the i-th group of delayed neutrons in all fission neutrons... ieff The total effective share β of delayed-emission neutrons among all fission neutrons. eff; mean generation time Λ of instantaneous neutrons; precursor nucleus concentration C of the i-th delayed neutron group at time t. i (t); the time interval Δt before and after the rod falls; the intensity q of the external neutron source; the decay constant λ of the fission fragments of the i-th delayed neutron precursor nucleus. i After the rod falls, the reactor period is T1, and the neutron dynamics equations of the reactor before the rod falls are described as formulas (3) and (4).

[0051]

[0052]

[0053] The neutron dynamics equations of the post-drop point are described by equations (5) and (6).

[0054]

[0055]

[0056] Formulas (7) and (8) are obtained by subtracting the neutron dynamics equations of the point pile before and after the rod is dropped.

[0057]

[0058]

[0059] Formula (9) is derived from formula (7).

[0060]

[0061] In the above formula (9), If the bar is in a critical state before dropping, i.e., ρ0 = 0, then formulas (10) and (11) are obtained.

[0062]

[0063]

[0064] Based on the above conditions, formula (8) can be used to obtain formula (12).

[0065]

[0066] In the formula It is an unknown quantity, but since the time of the dropping process is relatively short, then... Therefore, it is assumed that the change in ci is equal to the product of the average rate of change of ci(t) in this process and time, thus obtaining formula (13).

[0067]

[0068] Then, based on formulas (12) and (13), we get formula (14).

[0069]

[0070] Substituting formula (14) into formula (9), we obtain the reactive formula (15) introduced by the control rod drop.

[0071]

[0072] The traditional differential formula is formula (16).

[0073]

[0074] Formula (15) has two more terms than the traditional differential formula (16). The first additional term... The effect of transient neutron changes is taken into account. This term can only be ignored when the transient neutron change ends and the neutron density changes to an asymptotic value, i.e., the period T1 is large enough.

[0075] The extra second item The effect of delayed neutrons is taken into account, and its contribution is positively correlated with Δt. This term can be ignored when Δt is sufficiently small.

[0076] To verify the accuracy of the improved formula, a comparative analysis is conducted. The reactor is initially in a critical state, assuming an extremely short rod drop time of 1E-4s, a rod drop value of 1000 pcm, and delayed neutron emission data as shown in Table 1.

[0077] Table 1 Delayed Neutron Data

[0078]

[0079] The results of processing the bar after dropping using the traditional dropping bar method and the optimized dropping bar method are shown in Table 2 below.

[0080] Table 2 Comparison of results from the instantaneous drop bar method

[0081]

[0082] As shown in Table 2, neither method can obtain the drop value at the initial moment after the instantaneous rod drop. This is because the calculation still uses the previous value, which is not yet fully fallen at this time. After 0.0002 seconds, the optimized method begins to give a correct result, while the traditional rod drop method only gives a correct result after 0.01 seconds. This is because the instantaneous neutrons also need sufficient time to decay. At 1 second, the traditional rod drop method produces a large error, while the optimized method has a much smaller error. This is because after a longer time, the influence of the delayed neutron precursor nucleus becomes non-negligible, and the traditional rod drop method's failure to consider delayed neutrons leads to a larger error.

[0083] Table 3 simulates the rod dropping operation in a typical commercial pressurized water reactor, with a drop time in the order of seconds (1.85 seconds). Other conditions remain the same as the previous example. The results of several post-drop processing methods are shown in Table 3. As can be seen from the table, the error of the traditional rod dropping method exceeds 30% after the control rod has reached the bottom. The error of the optimized rod dropping method is significantly reduced because the effect of the delayed neutron precursor nucleus in the second-level drop time is no longer negligible.

[0084] Table 3 Comparison of results from the simulated drop bar method

[0085]

[0086] The above comparison shows that the optimized falling rod method, by considering the effects of both instantaneous and delayed neutrons, can significantly reduce the measurement error compared to the traditional method.

[0087] The following calculation of reactivity is based on an example where the time interval Δt before and after the drop bar is 1.85 seconds.

[0088] Optimized formula for the dropping bar method Λ, λ i β ieff and β eff All are neutronics parameters, considered constants during the experiment, and can be calculated from theoretical data. Data from Table 1 is used here, with Λ being 2.69 × 10⁻⁶. -5 s.

[0089] Before the test begins, confirm that the reactor core is in a critical state. At the start of the test, insert the control rod to be tested to the bottom of the reactor core.

[0090] Before the rod drop begins, t0 = 0, and the corresponding external nuclear instrument signal value is recorded as n0 = 1. Based on the rod drop time, the end time is determined to be t1 = 1.85, and the corresponding external nuclear instrument signal value is recorded as n1 = 0.337541. At any point after the rod drop ends, t2 = 2, and the corresponding external nuclear instrument signal value is recorded as n2 = 0.331106. Here, t0 and t1 are determined according to the actual rod drop time, while t2 can be any point after the rod drop ends. t2 is chosen to calculate the period T1 after the rod drop. The ratio can be taken as the intermediate range or the power range signal.

[0091] Δt = t1 - t0 = 1.85

[0092]

[0093] Substituting the above values ​​and the delayed neutron parameter into formula (2) yields the reactivity after the rod is dropped.

[0094]

[0095] The value of the control rod to be tested is |ρ1| = 1088.3 pcm.

[0096] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for calculating the value of a control rod using the drop rod method, characterized in that, include: The initial time t0 before the start of the test control rod drop and the neutron flux density n0 corresponding to the initial time t0, the end time t1 of the drop and the neutron flux density n1 corresponding to the end time t1, and any time t2 after the end of the drop and the neutron flux density n2 corresponding to the end time t2 are obtained. Based on the time t1 at which the rod falls, the neutron flux density n1 corresponding to the time t1, the arbitrary time t2, and the neutron flux density n2 corresponding to the arbitrary time t2, and in conjunction with formula (1), the period T1 after the rod falls is calculated. Obtain the average generation time Λ of instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments i The total effective share β of moderately emitted neutrons in all fission neutrons eff The time interval Δt before and after the drop bar; Based on the neutron flux density n0 corresponding to the initial time t0, the average generation time Λ of the instantaneous neutrons, and the total effective share β of the delayed neutrons in all fission neutrons. eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective proportion β of the i-th group of delayed neutrons in all fission neutrons. ieff and the decay constant λ of the i-th group of delayed neutron precursor nuclear fission fragments i The value of the control rod under test, |ρ1|, is calculated using formula (2).

2. The method according to claim 1, characterized in that, The acquisition of the initial time t0 before the start of the test control rod drop and the neutron flux density n0 corresponding to the initial time t0, the end time t1 after the drop and the neutron flux density n1 corresponding to the end time t1, and any time t2 after the drop and the neutron flux density n2 corresponding to the end time t2 includes: Before the drop test begins, confirm that the reactor core is in a critical state; Record the initial time t0 of the control rod under test before the rod drops begin, and the neutron flux density n0 corresponding to the initial time t0 measured by the external nuclear instrument. At the start of the drop test, the control rod to be tested is inserted to the bottom of the pile; After the drop test, the neutron flux density n1 corresponding to the end time t1 of the drop test and the end time t1 measured by the external nuclear instrument is recorded, as well as the neutron flux density n2 corresponding to any time t2 after the drop test and the end time t2 measured by the external nuclear instrument.

3. A device for calculating the value of a control rod using the drop rod method, characterized in that, include: The acquisition module is used to acquire the initial time t0 before the start of the test control rod drop and the neutron flux density n0 corresponding to the initial time t0, the end time t1 before the start of the drop and the neutron flux density n1 corresponding to the end time t1, and any time t2 after the end of the drop and the neutron flux density n2 corresponding to the end time t2. It also acquires the average generation time Λ of the instantaneous neutrons and the effective share β of the i-th group of delayed neutrons in all fission neutrons. ieff The time interval Δt before and after the rod falls, and the decay constant λ of the i-th group of slow-emitting neutron precursor nuclear fission fragments. i The total effective share β of moderately emitted neutrons in all fission neutrons eff ; The calculation module is used to calculate the period T1 after the rod falls based on the time t1 at which the rod falls, the neutron flux density n1 corresponding to the time t1 at which the rod falls, the arbitrary time t2, and the neutron flux density n2 corresponding to the arbitrary time t2, and in combination with formula (1). And based on the neutron flux density n0 corresponding to the initial time t0, the mean generation time Λ of the instantaneous neutrons, and the total effective share β of the delayed neutrons in all fission neutrons. eff The period T1 after the rod falls, the time interval Δt before and after the rod falls, and the effective proportion β of the i-th group of delayed neutrons in all fission neutrons. ieff and the decay constant λ of the i-th group of delayed neutron precursor nuclear fission fragments i The value of the control rod under test, |ρ1|, is calculated using formula (2).

4. A computer-readable storage medium storing executable instructions for a computer thereon, characterized in that, When the executable instructions are executed by the processor, they implement a method for calculating the value of a control rod using the drop bar method as described in claim 1 or 2.

5. An electronic device, characterized in that, include: A processor for executing a method for calculating the value of a control rod using the drop bar method as described in claim 1 or 2; And a memory for storing the executable instructions of the processor.

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