Measurement Methods of Reactor Reactivity and Subcriticality

Abstract

A method for measuring reactor reactivity and subcriticality. The reactor reactivity measurement method comprises the following steps: adjusting the actual reactivity of the reactor to change the neutron count of the reactor; and obtaining the measured reactivity of the adjusted reactor according to the change value of the neutron count. In the method of this embodiment, the error between the measured value-measured reactivity and the actual reactivity obtained by measuring the actual reactivity of the reactor using the change value of the neutron count is small, and a more accurate actual reactivity can be obtained, which is beneficial to the critical safety supervision of the reactor.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of nuclear reaction technology, and in particular to a method for measuring reactor reactivity and subcriticality. Background Art

[0002] The reactivity of a reactor is a physical quantity that reflects the state of the reactor and characterizes the degree to which the reactor deviates from the critical state.

[0003] Commonly used reactivity measurement methods in nuclear power plants include: boron adjustment method, rod replacement method, dynamic rod engraving method and reverse dynamic method. Among them, the boron adjustment method measures the micro-integral value of the control rod by adjusting the boron concentration, but the measurement time is long and the cost is high; the rod replacement method does not require boron adjustment, takes a little less time, and can measure the integral value of the control rod; the dynamic rod engraving method inserts the control rod, combines calculation analysis with measured data, and can measure the integral value of the control rod more accurately in a short time; the reverse dynamic method uses the point pile kinetic equation to solve the reactivity or effective value-added coefficient. Summary of the invention

[0004] The embodiment of the present invention provides a method for measuring reactor reactivity and subcriticality.

[0005] A reactor reactivity measurement method according to an embodiment of the present invention comprises the following steps: adjusting the actual reactivity of the reactor to change the neutron count of the reactor; and obtaining the measured reactivity of the adjusted reactor according to the change value of the neutron count.

[0006] A method for measuring reactor subcriticality in an embodiment of the present invention is the method of the above embodiment; the subcriticality of the reactor is obtained according to the obtained measured reactivity.

[0007] In the reactor reactivity measurement method of the embodiment of the present invention, the error between the measured value - measured reactivity and the actual reactivity obtained by measuring the actual reactivity of the reactor using the change value of the neutron count in the method of this embodiment is small, and a more accurate actual reactivity can be obtained. This method can reduce the error between the measured reactivity and the actual reactivity inherent in the reactor, improve the measurement accuracy of the actual reactivity, and is beneficial to the critical safety of the reactor.

[0008] Additional aspects and advantages of the embodiments of the present invention will be given in part in the following description, and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0010] Figure 14 is a flow chart of a method for measuring reactor reactivity according to an embodiment of the present invention.

[0011] Figure 2 It is a schematic diagram of a reactor reactivity measurement method according to a first embodiment of the present invention.

[0012] Figure 3 Schematic diagram of a reactor reactivity measurement method according to a second embodiment of the present invention.

[0013] Figure 4 is a schematic diagram of a reactor reactivity measurement method according to a third embodiment of the present invention. and

[0014] Figure 5 It is a schematic diagram of a reactor reactivity measurement method according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0015] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0016] The power and neutron count of the reactor are both physical quantities that characterize the same reactor. Therefore, the power and neutron count of the reactor in the following embodiments can be replaced with each other.

[0017] Figure 1 is a flow chart of a method for measuring reactor reactivity according to an embodiment of the present invention. Figure 1 , the reactor reactivity measurement method may include step S1001 and step S1002.

[0018] S1001: Adjust the actual reactivity of the reactor so that the neutron count of the reactor changes.

[0019] S1002: Obtain the measured reactivity of the reactor after adjustment according to the change value of the neutron count. That is, the obtained measured reactivity is used to measure the actual reactivity of the reactor after adjustment.

[0020] This embodiment obtains the measured reactivity of the reactor based on the change value of the reactivity. Compared with the conventional inverse dynamic method, the measurement method of this embodiment can measure the reactivity of the reactor when the reactor is in a subcritical, critical or supercritical state, and is applicable to a wider range of scenarios. Compared with the drop rod method, the method of this embodiment does not need to judge the specific time of adjusting the reactivity. It only needs to obtain the change value of the neutron count according to the neutron count collected during the operation to obtain the actual reactivity of the reactor, and the actual reactivity obtained has high accuracy. In the method of this embodiment, the error between the measured value obtained by measuring the actual reactivity of the reactor using the change value of the neutron count and the actual reactivity is small, and a more accurate actual reactivity can be obtained. Reducing the error between the measured reactivity and the actual reactivity inherent in the reactor and improving the measurement accuracy of the actual reactivity are beneficial to the critical safety of the reactor.

[0021] The method of this embodiment can carry out the measurement of reactivity under the subcritical state, and can be used in the method of carrying out subcritical rod etching to reduce the time spent on rod etching and increase economy.

[0022] In a reactor, when in a subcritical state, under a fixed source strength, the neutron count is positively correlated with the actual reactivity. When the actual reactivity increases, the neutron count increases; when the actual reactivity decreases, the neutron count decreases. In this embodiment, since the neutron source intensity of the reactor is not changed, the neutron source intensity of the reactor remains unchanged. By changing the actual reactivity, the neutron count is changed, and the measured reactivity of the adjusted reactor is obtained by the change value of the neutron count. The obtained measured reactivity is close to the actual reactivity of the reactor.

[0023] In the following, the initial number of neutrons is represented by N0, the final number of neutrons is represented by N1, and the intermediate number of neutrons is represented by N(t). i is the effective fraction of delayed neutrons in group i. Λ is the neutron generation time. i is the decay constant of the delayed neutron precursor nucleus of the i-th group. The measured reactivity is represented by ρ, the actual reactivity before adjustment is represented by ρ0, and the actual reactivity after adjustment is represented by ρ1.

[0024] In the first derivation using the formula, when calculating the measured reactivity based on the inverse dynamic method, the existence of an external neutron source is taken into account, and the formula used in the method of this embodiment is derived based on this.

[0025] In the reactor, the point reactor kinetic equation 1 with an external neutron source is:

[0026]

[0027]

[0028] According to the above point pile kinetic equation, the inverse kinetic equation 2 with an external neutron source is:

[0029]

[0030] In addition, when the reactor is in the final state, the point reactor kinetic equation can be used to obtain

[0031] Formula 3:

[0032]

[0033] When the measured reactivity of the adjusted reactor is the actual reactivity, there is a public

[0034] Formula 4:

[0035]

[0036] Now, substituting equation 4 into equation 2, we get equation 5:

[0037]

[0038] In the second derivation using the formula, when calculating the measured reactivity based on the inverse dynamic method, the influence of the external neutron source is considered to be removed, and the formula used in this experimental method is derived based on this.

[0039] In the reactor, the point reactor kinetic equation 6 without neutron source is:

[0040]

[0041]

[0042] According to the above point pile kinetic equation, the inverse kinetic equation 7 without neutron source is:

[0043]

[0044] After adjusting the reactivity of the reactor from ρ0 to ρ1, the neutron count N0 will change to N1. During the change of the neutron count, the neutron count N(t) at any time minus N1, that is, N(t)-N1, represents the change value of the neutron count in the reactor, which does not contain the influence of the external neutron source term or background. Therefore, substituting N(t)-N1 into equation 7, we can get equation 8:

[0045]

[0046] When the time t is much greater than the initial time t0, Formula 9 can be obtained:

[0047]

[0048] Substituting formula 9 into formula 8, we can get formula 10:

[0049]

[0050] Obtaining the measured reactivity of the reactor after adjustment according to the change value of the neutron count includes the following steps: Based on the inverse dynamic method, obtaining the measured reactivity of the reactor after adjustment according to the change value of the neutron count. That is, substituting the change value of the neutron count into the inverse dynamic equation formula 10 or formula 5, the measured reactivity of the reactor after adjustment can be obtained.

[0051] In a first embodiment, regulating the reactivity of a reactor includes the steps of controlling the transient introduction of positive reactivity into the reactor. Figure 2 Schematic diagram of a method for measuring reactor reactivity according to a first embodiment of the present invention. Figure 2 The change process of the measured value of the neutron count is obtained during the entire operation, while the change in measured reactivity is calculated after the operation is completed. Of course, if the final neutron number N1 is measured in advance, the reactivity of the reactor when it is in the final state can also be obtained in real time and quickly. Figure 2 The horizontal axis is time, in seconds.

[0052] The faster the actual reactivity changes or the shorter the time of the actual reactivity change, the more timely and accurately this embodiment can measure the actual reactivity of the adjusted reactor, and the more timely and accurately it can reflect the subcritical state of the adjusted reactor, which can speed up the measurement of the actual reactivity of the reactor and reduce the operation time of the reactor during the measurement process.

[0053] Specifically, the reactor is configured to have a regulation state. When the reactor is in the regulation state, the reactivity of the reactor is adjusted. When the reactor is in the regulation state, control is performed to transiently introduce positive reactivity into the reactor.

[0054] Specifically, the reactor is further configured to have an initial state and an end state, the adjustment state is located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time. When the reactor is in the initial state, the neutron count is measured; when the reactor is in the end state, the neutron count is stopped.

[0055] Furthermore, the first time is greater than or equal to 300 seconds. That is, the time from the initial state to the adjustment state is greater than or equal to 300 seconds, so as to enhance the accuracy of the measured responsiveness.

[0056] When the reactor is in the final state, the neutron count is measured as the final neutron count. When the reactor is between the initial state and the final state, the neutron count is measured as the intermediate neutron count.

[0057] In some embodiments, the change value of the neutron count is the difference between the intermediate neutron count and the final neutron count, that is, the intermediate neutron count minus the final neutron count. The final neutron count can be understood as the neutron background count caused by the neutron source when the reactor is in the final state. The intermediate neutron count at any time during the operation is deducted from the influence of the background count, that is, the change value of the neutron count is substituted into the inverse dynamic method, and the measured reactivity of the reactor at that time can be obtained.

[0058] See also Figure 2 , before the reactor is in the adjustment state, an external neutron source injects neutrons into the reactor core, so that the neutron count approaches N0, and the measured reactivity before adjustment approaches 0; when the reactor is in the adjustment state, the reactor begins to be adjusted, and positive reactivity is instantly introduced into the reactor; when the reactor is between the adjustment state and the end state, the neutron count rises from N0 to N1, and the actual reactivity decays from 0 to ρ1; when the reactor is in the end state, the neutron count approaches N1, and the measured reactivity ρ approaches ρ1, that is, the difference between the measured reactivity ρ and the actual reactivity is small. The neutron count approaches N1 means that the neutron count rises to a certain neutron count and fluctuates. The average value of the neutron count at any time is the same, which can determine that the reactor is in the end state and stop measuring the neutron count.

[0059] In a second embodiment, regulating the reactivity of the reactor includes the step of controlling the transient introduction of negative reactivity into the reactor. Figure 3 Schematic diagram of a reactor reactivity measurement method according to a second embodiment of the present invention. Figure 3 The change process of the measured value of the neutron count is obtained during the entire operation, while the change of the measured reactivity is calculated after the operation is completed. Of course, if the final neutron number N1 is measured in advance, the reactivity of the adjusted reactor can also be quickly obtained in real time. Figure 3 The horizontal axis is time, in seconds.

[0060] The faster the actual reactivity changes or the shorter the time of the actual reactivity change, the more timely and accurately this embodiment can measure the actual reactivity of the adjusted reactor, and the more timely and accurately it can reflect the subcritical state of the adjusted reactor, which can speed up the measurement of the actual reactivity of the reactor and reduce the operation time of the reactor during the measurement process.

[0061] Specifically, the reactor is configured to have a regulation state, and when the reactor is in the regulation state, the reactivity of the reactor begins to be regulated. When the reactor is in the regulation state, control is performed to transiently introduce negative reactivity into the reactor.

[0062] Specifically, the reactor is further configured to have an initial state and an end state, the adjustment state is located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time. When the reactor is in the initial state, the neutron count is measured; when the reactor is in the end state, the neutron count is stopped.

[0063] Furthermore, the first time is greater than or equal to 300 seconds. That is, the time from the initial state to the adjustment state is greater than or equal to 300 seconds, so as to enhance the accuracy of the measured responsiveness.

[0064] When the reactor is in the final state, the neutron count is measured as the final neutron count. When the reactor is between the initial state and the final state, the neutron count is measured as the intermediate neutron count.

[0065] In some embodiments, the change value of the neutron count is the difference between the intermediate neutron count and the final neutron count, that is, the intermediate neutron count minus the final neutron count. The final neutron count can be understood as the neutron background count caused by the neutron source when the reactor is in the final state. The intermediate neutron count at any time during the operation is deducted from the influence of the background count, that is, the change value of the neutron count is substituted into the inverse dynamic method, and the measured reactivity of the reactor at that time can be obtained.

[0066] In other embodiments, the reactor is further configured to have an initial state. When the reactor is between the initial state and the adjustment state, the measured value of the neutron count is the initial neutron count. The average value of the initial neutron count in the second time before the adjustment state is the predetermined initial neutron count. When the final neutron count is less than one percent of the initial neutron count, the change value of the neutron count is the intermediate neutron count. When the final neutron count is less than one percent of the predetermined initial neutron count, that is, when the neutron background count in the core after adjustment is negligible compared to before adjustment, the measured reactivity of the reactor after adjustment can be obtained directly through the intermediate neutron count.

[0067] Further, the second time is less than or equal to the first time. For example, when the first time is 300 seconds, the second time may be 10 seconds, and the predetermined initial neutron number is the average value of the neutron number measured within 10 seconds before the reactivity adjustment of the reactor.

[0068] See also Figure 3Before the reactor is in the adjustment state, an external neutron source injects neutrons into the reactor core, so that the neutron count is stable and close to N0, and the measured reactivity before adjustment is close to 0; when the reactor is in the adjustment state, the reactor begins to be adjusted, and negative reactivity is instantaneously introduced into the reactor; when the reactor is between the adjustment state and the end state, the neutron count decays from N0 to N1, and the actual reactivity decays from 0 to ρ1; when the reactor is in the end state, the neutron count approaches N1, and the measured reactivity ρ approaches ρ1, that is, the difference between the measured reactivity ρ and the actual reactivity is small. The neutron count approaches N1 means that the neutron count drops to a certain neutron count and fluctuates. The average value of the neutron count at any time is the same, which can determine that the reactor is in the end state and stop measuring the neutron count.

[0069] In a third embodiment, positive reactivity is introduced into the reactor over a controlled period of time. Figure 4 Schematic diagram of a reactor reactivity measurement method according to a third embodiment of the present invention. Figure 4 The change process of the measured value of the neutron count is obtained during the entire operation, while the change in measured reactivity is calculated after the operation is completed. Of course, if the final neutron number N1 is measured in advance, the reactivity of the reactor when it is in the final state can also be obtained in real time and quickly. Figure 4 The horizontal axis is time, in seconds.

[0070] Specifically, the reactor is configured to have a regulation state and a suspension state. When the reactor is in the regulation state, control introduces positive reactivity into the reactor. When the reactor is in the suspension state, control stops introducing positive reactivity into the reactor.

[0071] Specifically, the reactor is further configured to have an initial state and an end state, the adjustment state and the suspension state are located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time. When the reactor is in the initial state, the neutron count is measured; when the reactor is in the end state, the neutron count is stopped.

[0072] Furthermore, the first time is greater than or equal to 300 seconds. That is, the time from the initial state to the adjustment state is greater than or equal to 300 seconds, so as to enhance the accuracy of the measured responsiveness.

[0073] When the reactor is in the final state, the neutron count is measured as the final neutron count. When the reactor is between the initial state and the final state, the neutron count is measured as the intermediate neutron count.

[0074] In some embodiments, the change value of the neutron count is the difference between the intermediate neutron count and the final neutron count, that is, the intermediate neutron count minus the final neutron count. The final neutron count can be understood as the neutron background count caused by the neutron source when the reactor is in the final state. The intermediate neutron count at any time during the operation is deducted from the influence of the background count, that is, the change value of the neutron count is substituted into the inverse dynamic method, and the measured reactivity of the reactor at that time can be obtained.

[0075] See also Figure 4 , before the reactor is in the adjustment state, an external neutron source injects neutrons into the reactor core, so that the neutron count approaches N0, and the measured reactivity before adjustment approaches 0; when the reactor is in the adjustment state, the reactor begins to be adjusted, and positive reactivity begins to be continuously introduced into the reactor; when the reactor is in the suspension state, the reactor is stopped from being adjusted, and the positive reactivity is stopped from being introduced into the reactor; when the reactor is between the adjustment state and the end state, the neutron count rises from N0 to N1, and the actual reactivity decays from 0 to ρ1; when the reactor is in the end state, the neutron count approaches N1, and the measured reactivity ρ approaches ρ1, that is, the difference between the measured reactivity ρ and the actual reactivity is small. The neutron count approaches N1 means that the neutron count rises to a certain neutron count and fluctuates. The average value of the neutron count at any time is the same, which can determine that the reactor is in the end state and stop measuring the neutron count. Figure 4 The positive reactivity is introduced over a period of time and the introduction time is long.

[0076] In a fourth embodiment, negative reactivity is controlled to be introduced into the reactor over a period of time. Figure 5 Schematic diagram of a reactor reactivity measurement method according to a fourth embodiment of the present invention. Figure 5 The change process of the measured value of the neutron count is obtained during the entire operation, while the change in measured reactivity is calculated after the operation is completed. Of course, if the final neutron number N1 is measured in advance, the reactivity of the reactor when it is in the final state can also be obtained in real time and quickly. Figure 5 The horizontal axis is time, in seconds.

[0077] Specifically, the reactor is configured to have a regulation state and a suspension state. When the reactor is in the regulation state, control is inducing negative reactivity to the reactor. When the reactor is in the suspension state, control stops introducing negative reactivity to the reactor.

[0078] Specifically, the reactor is further configured to have an initial state and an end state, the adjustment state and the suspension state are located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time. When the reactor is in the initial state, the neutron count is measured; when the reactor is in the end state, the neutron count is stopped.

[0079] Furthermore, the first time is greater than or equal to 300 seconds. That is, the time from the initial state to the adjustment state is greater than or equal to 300 seconds, so as to enhance the accuracy of the measured responsiveness.

[0080] When the reactor is in the final state, the neutron count is measured as the final neutron count. When the reactor is between the initial state and the final state, the neutron count is measured as the intermediate neutron count.

[0081] In some embodiments, the change value of the neutron count is the difference between the intermediate neutron count and the final neutron count, that is, the intermediate neutron count minus the final neutron count. The final neutron count can be understood as the neutron background count caused by the neutron source when the reactor is in the final state. The intermediate neutron count at any time during the operation is deducted from the influence of the background count, that is, the change value of the neutron count is substituted into the inverse dynamic method, and the measured reactivity of the reactor at that time can be obtained.

[0082] In other embodiments, when the reactor is between the initial state and the adjustment state, the measured value of the neutron count is the initial neutron count. The average value of the initial neutron count in the second time before the adjustment state is the predetermined initial neutron count. When the final neutron count is less than one percent of the predetermined initial neutron count, the change value of the neutron count is the intermediate neutron count. When the final neutron count is less than one percent of the initial neutron count, that is, when the neutron background count in the core when the reactor is in the final state is negligible compared to the initial state, the measured reactivity of the adjusted reactor can be obtained directly through the intermediate neutron count.

[0083] Further, the second time is less than or equal to the first time. For example, when the first time is 300 seconds, the second time may be 10 seconds, and the predetermined initial neutron number is the average value of the neutron number measured within 10 seconds before the reactivity adjustment of the reactor.

[0084] See also Figure 5 , before the reactor is in the adjustment state, an external neutron source injects neutrons into the reactor core, so that the neutron count approaches N0, and the measured reactivity before adjustment approaches 0; when the reactor is in the adjustment state, the reactor begins to be adjusted, and negative reactivity begins to be continuously introduced into the reactor; when the reactor is in the suspension state, the reactor is stopped from being adjusted, and negative reactivity is stopped from being introduced into the reactor; when the reactor is between the adjustment state and the end state, the neutron count decays from N0 to N1, and the actual reactivity decays from 0 to ρ1; when the reactor is in the end state, the neutron count approaches N1, and the measured reactivity ρ approaches ρ1, that is, the difference between the measured reactivity ρ and the actual reactivity is small. The neutron count approaches N1 means that the neutron count drops to a certain neutron count and fluctuates. The average value of the neutron count at any time is the same, which can determine that the reactor is in the end state and stop measuring the neutron count. Figure 5 The negative reactivity is introduced over a period of time and the introduction time is long.

[0085] In some embodiments, when the reactor is between the initial state and the adjustment state, the initial neutron count tends to be stable. The term "tends to be stable" means that the average value of the neutron count at any time is the same.

[0086] In other embodiments, when the reactor is in an initial state, the initial neutron number may also be in an unstable state. When in an unstable state, the method of this embodiment can also be used to obtain a relatively accurate measurement of reactivity.

[0087] Specifically, when the reactor is in the terminal state, the final neutron count tends to be stable. The final neutron count tends to be stable means that the average value of the neutron count in any time period before the reactor is in the terminal state is the same.

[0088] In some embodiments, adjusting the reactivity of the reactor so that the neutron count of the reactor changes includes the following steps: controlling the introduction of positive reactivity into the reactor to increase the actual reactivity of the reactor so that the neutron count increases.

[0089] In other embodiments, adjusting the reactivity of the reactor to change the neutron count of the reactor includes the following steps: controlling the introduction of negative reactivity into the reactor to reduce the actual reactivity of the reactor so that the neutron count decreases.

[0090] The method for measuring reactor subcriticality comprises the following steps (1) and (2).

[0091] Step (1): Under the subcritical state, the reactivity is measured by the method of the above embodiment.

[0092] Step (2): Obtain the subcriticality of the reactor based on the measured reactivity.

[0093] When the reactor is in a subcritical state, the actual reactivity of the reactor will change the neutron count in the reactor. The neutron count will change accordingly according to the current state of the reactor and the change in actual reactivity, so that the neutron count in the reactor will reach a new balance again. Therefore, this embodiment extracts the change value of the neutron count during the reactivity change process, and then uses the inverse dynamic method to obtain a measured reactor that is close to the actual reactivity. Compared with the conventional inverse dynamic method to measure the reactivity of the reactor, this embodiment measures the reactivity of the reactor in a subcritical state.

[0094] Specifically, before the reactor is in the adjustment state, the core of the reactor may or may not have been injected with external neutrons. Since the state or reactivity of the reactor may change, the neutron count at any moment may be in an increasing or decreasing state compared with the previous moment, and the measured reactivity of the reactor may also be positive or negative; when the reactor is in the adjustment state, the actual reactivity is changed, resulting in instantaneous changes in the neutron count and the measured reactivity; when the reactor is between the adjustment state and the end state, the neutron count increases or decreases, and the measured reactivity decreases; when the reactor is in the end state, the neutron count approaches N1, and the measured reactivity ρ approaches ρ1. The subcriticality of the reactor is obtained based on ρ. The larger the absolute value of ρ, the greater the subcriticality of the reactor.

[0095] Under some special conditions, a reactivity disturbance is introduced in the adjustment state to change the neutron count, but the actual reactivity of the final state does not change, that is, the actual reactivity ρ0 of the initial state is equal to the actual reactivity ρ1 of the final state. This method can also be used to measure the reactivity of the current reactor.

[0096] Before starting to adjust the reactivity of the reactor, the neutron count is measured for a period of time to improve the accuracy of the obtained subcriticality; the neutron count in the reactor during the adjustment of the reactivity may be in a steady state or in a non-steady state.

[0097] Preferably, before the reactor is in the initial state, the neutron count is stable at N0 and the measured reactivity is 0. In this way, when the neutron counts in the initial state and the final state are sufficient to maintain the neutron counts stable, many different subcriticalities can be measured by directly combining different initial states and final states.

[0098] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0099] In the description of this specification, the description with reference to the terms "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0100] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for measuring reactor reactivity, characterized in that: The method comprises the following steps: adjusting the actual reactivity of the reactor so that the neutron count of the reactor changes; Obtaining measured reactivity of the reactor after adjustment according to the change in the neutron count; The regulating the reactivity of the reactor comprises the following steps: controlling the transient introduction of positive reactivity into the reactor; or controlling the transient introduction of negative reactivity into the reactor; The reactor is configured to have a regulation state, and when the reactor is in the regulation state, regulation of the reactivity of the reactor begins; wherein, when the reactor is in the regulation state, positive reactivity is instantaneously introduced into the reactor; or When the reactor is in the regulation state, controlling the instantaneous introduction of negative reactivity into the reactor; The reactor is further configured to have an initial state and an end state, the adjustment state is located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time; When the reactor is between the initial state and the adjustment state, the measured value of the neutron count is the initial neutron number; the average value of the initial neutron number in the second time before the adjustment state is the predetermined initial neutron number; when the reactor is in the end state, the measured value of the neutron count is the final neutron number; when the reactor is between the initial state and the end state, the measured value of the neutron count is the intermediate neutron number; the second time is less than or equal to the first time; Wherein, when the final neutron number is less than one percent of the predetermined initial neutron number, the change value of the neutron count is the intermediate neutron number; The step of obtaining the measured reactivity of the reactor after adjustment according to the change in the neutron count comprises the following steps: Based on the inverse dynamics method, the measured reactivity of the reactor after adjustment is obtained according to the change value of the neutron count.

2. The method according to claim 1, characterized in that Among them, β i is the effective fraction of delayed neutrons in group i; Λ is the neutron generation time; λ i is the decay constant of the delayed neutron precursor nucleus of the i-th group; N(t)-N1 is the change value of the neutron count; N1 is the number of neutrons at the end; N(t) is the number of intermediate neutrons; ρ is the measured reactivity.

3. The method according to claim 1, characterized in that The reactor is further configured to have an initial state and an end state, the adjustment state is located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time; When the reactor is in the end state, the measured value of the neutron count is the end neutron number; when the reactor is between the initial state and the end state, the measured value of the neutron count is the intermediate neutron number; The change value of the neutron count is the difference between the middle neutron count and the last neutron count.

4. The method according to claim 1, characterized in that: The reactor is configured to have a regulation state and an abort state; wherein, when the reactor is in the regulation state, controlling the introduction of positive reactivity or negative reactivity into the reactor; When the reactor is in the aborted state, control stops introducing positive reactivity or negative reactivity into the reactor.

5. The method according to claim 4, characterized in that The reactor is further configured to have an initial state and an end state, the adjustment state and the suspension state are located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time; When the reactor is in the end state, the measured value of the neutron count is the end neutron number; when the reactor is between the initial state and the end state, the measured value of the neutron count is the intermediate neutron number; The change value of the neutron count is the difference between the middle neutron count and the last neutron count.

6. The method according to claim 4, characterized in that The reactor is further configured to have an initial state and an end state, the adjustment state and the suspension state are located between the initial state and the end state, and the initial state and the adjustment state are separated by a first time; When the reactor is between the initial state and the adjustment state, the measured value of the neutron count is the initial neutron number; the average value of the initial neutron number in the second time before the adjustment state is the predetermined initial neutron number; when the reactor is in the end state, the measured value of the neutron count is the end neutron number; when the reactor is between the initial state and the end state, the measured value of the neutron count is the intermediate neutron number; When the final neutron number is less than one percent of the predetermined initial neutron number, the change value of the neutron count is the intermediate neutron number.

7. The method according to claim 1 or 6, characterized in that: When the reactor is between the initial state and the adjustment state, the initial neutron number tends to be stable.

8. The method according to claim 1 or 3 or 5 or 6, characterized in that: When the reactor is in the final state, the final neutron number tends to be stable.

9. The method according to claim 1, characterized in that: The step of adjusting the reactivity of the reactor so that the neutron count of the reactor changes comprises the following steps: The positive reactivity is introduced into the reactor to increase the actual reactivity of the reactor so that the neutron count increases.

10. The method according to claim 1, characterized in that The step of adjusting the reactivity of the reactor so that the neutron count of the reactor changes comprises the following steps: The negative reactivity is introduced into the reactor to reduce the actual reactivity of the reactor so that the neutron count decreases.

11. A method for measuring reactor subcriticality, characterized in that: The method comprises: In a subcritical state, the method of any one of claims 1 to 10; The subcriticality of the reactor is obtained based on the measured reactivity obtained.

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