阅读说明：本技术 一种基于不确定度分析的核反应堆次临界度测量方法 (Nuclear reactor subcritical degree measuring method based on uncertainty analysis ) 是由 汪文聪 刘才学 黄礼渊 徐建军 乔红威 韩熙明 魏东 郭燕 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种基于不确定度分析的核反应堆次临界度测量方法,包括以下步骤：对测量中子信号的不确定度分析,基于最优化算法,获得具有最优不确定度的中子信号测量数据组,并计算其不确定度,用于后续次临界度测量分析；构建基于不确定度分析的次临界度修正模型,确定修正因子及其不确定度,用于后续次临界度分析；构建基于不确定度分析的次临界度测量模型,结合步骤1获得的中子信号数据、修正因子数据及其不确定度进行不确定度分析,得出最终次临界度测量结果及其不确定度。本发明采用基于不确定度分析的数学算法,减小中子信号测量不确定度,减小修正因子引入的不确定度,提高次临界度测量效率和准确性。(The invention discloses a nuclear reactor subcritical degree measuring method based on uncertainty analysis, which comprises the following steps of: analyzing the uncertainty of the measured neutron signal, obtaining a neutron signal measurement data group with the optimal uncertainty based on an optimization algorithm, and calculating the uncertainty of the neutron signal measurement data group for the subsequent subcritical measurement analysis; constructing a subcritical degree correction model based on uncertainty analysis, determining a correction factor and uncertainty thereof, and using the correction factor and the uncertainty thereof for subsequent subcritical degree analysis; and (3) constructing a subcritical degree measurement model based on uncertainty analysis, and carrying out uncertainty analysis by combining the neutron signal data, the correction factor data and the uncertainty thereof obtained in the step (1) to obtain a final subcritical degree measurement result and the uncertainty thereof. The invention adopts a mathematical algorithm based on uncertainty analysis, reduces the uncertainty of neutron signal measurement, reduces the uncertainty introduced by correction factors, and improves the efficiency and accuracy of subcritical measurement.)

1. A nuclear reactor subcritical degree measurement method based on uncertainty analysis is characterized by comprising the following steps:

step 1, analyzing uncertainty of a measured neutron signal, obtaining a neutron signal measurement data group with optimal uncertainty based on an optimization algorithm, and calculating the uncertainty of the neutron signal measurement data group for subsequent subcritical measurement analysis;

step 2, constructing a subcritical degree correction model based on uncertainty analysis, determining a correction factor and uncertainty thereof, and using the correction factor and uncertainty thereof for subsequent subcritical degree analysis;

and 3, constructing a subcritical degree measurement model based on uncertainty analysis, and carrying out uncertainty analysis by combining the neutron signal data, the correction factor data and the uncertainty thereof obtained in the step 1 to obtain a final subcritical degree measurement result and the uncertainty thereof.

2. A method of measuring the subcritical degree of a nuclear reactor based on uncertainty analysis according to claim 1, wherein in step 1, the operation of the optimization algorithm comprises the following steps:

measuring data x for n neutron signals measured in succession_iSelecting m continuous neutron signal measurement data from the measurement data, and calculating the uncertainty of the arithmetic mean value of the selected measurement data set based on an uncertainty analysis model;

changing the starting point and the end point of the selected m continuous neutron signal measurement data to obtain the uncertainty of the arithmetic mean value of all measurement data groups when m is 1,2, …, nAnd selecting a measurement data group with the optimal uncertainty from the measurement data group to serve as an optimal neutron signal measurement value for subsequent subcritical degree measurement analysis.

3. A nuclear reactor subcritical measurement method based on uncertainty analysis according to claim 1, characterized in that in step 2:

in the subcritical degree measurement process, if a correction algorithm is adopted to correct the measurement result, determining the uncertainty limit range of a correction factor based on the neutron signal uncertainty obtained in the step 1; when calculating the physical quantities required for correction, the calculation uncertainty of each physical quantity is controlled so that the synthetic uncertainty of the correction factor meets the requirement.

4. A nuclear reactor subcritical measurement method based on uncertainty analysis according to claim 1, characterized in that in step 2:

when the physical quantity required by correction is calculated, the calculation uncertainty of each physical quantity cannot reach the set minimum value, and the synthetic uncertainty of the correction factor cannot meet the requirement, the correction factor and the uncertainty thereof are directly calculated and used for subsequent subcritical degree analysis.

5. A nuclear reactor subcritical measurement method based on uncertainty analysis according to claim 1, characterized in that in step 2:

if no neutron signal measurement result exists when correction calculation is carried out, directly calculating a correction factor, and calculating the uncertainty of the correction factor for subsequent subcritical degree analysis.

Technical Field

The invention relates to a method for measuring the subcritical degree of a reactor, in particular to a method for measuring the subcritical degree of the reactor based on uncertainty analysis.

Background

According to the requirements of regulations, in the process of loading and unloading a reactor or in the process of debugging a control rod before a physical start test, in order to ensure nuclear safety, the subcritical degree of the reactor needs to be measured, and in the zero-power physical test of the reactor, the subcritical degree of the reactor also needs to be measured, so that data is provided for checking theoretical calculation.

The existing subcritical degree measuring method is based on a point reactor model, under the active and subcritical state in a reactor, neutrons in the reactor multiply m generations (m tends to be infinite), and the total number of neutrons in the reactor is in the following rule:

where N is the total number of neutrons in the reactor, N_cFor neutron signals in the detector, a constant related to the detector characteristics, S₀The neutron source is strong, and l is the lifetime of the prompt neutron.

From formula (2):

calculating to obtain an effective neutron multiplication factor k of a reference state_refAnd obtaining a neutron signal N of a reference state by measurement_c,refAnd neutron signal N of the state to be measured_c,1Then, the effective neutron multiplication factor k of the state to be measured can be obtained by the two formulas₁And realizing subcritical degree measurement:

in the process of measuring the subcritical degree, the neutron signal measured in each step is a key parameter for calculating the subcritical degree, the neutron signal is influenced by factors such as statistical fluctuation, high-voltage ripple fluctuation, amplification factor drift, electromagnetic interference and the like in the measuring process, and a certain uncertainty exists in the measuring result and is directly acted on a critical extrapolation result.

Disclosure of Invention

Aiming at the technical problems, the invention provides a nuclear reactor subcritical degree measurement method based on uncertainty analysis, which solves the problems, adopts a mathematical algorithm based on uncertainty analysis, reduces the uncertainty of neutron signal measurement, reduces the uncertainty introduced by a correction factor, and improves the efficiency and the accuracy of subcritical degree measurement.

The invention is realized by the following technical scheme:

a nuclear reactor subcritical degree measurement method based on uncertainty analysis comprises the following steps:

step 1, analyzing uncertainty of a measured neutron signal, obtaining a neutron signal measurement data group with optimal uncertainty based on an optimization algorithm, and calculating the uncertainty of the neutron signal measurement data group for subsequent subcritical measurement analysis;

step 2, constructing a subcritical degree correction model based on uncertainty analysis, determining a correction factor and uncertainty thereof, and using the correction factor and uncertainty thereof for subsequent subcritical degree analysis;

and 3, constructing a subcritical degree measurement model based on uncertainty analysis, and carrying out uncertainty analysis by combining the neutron signal data, the correction factor data and the uncertainty thereof obtained in the step 1 to obtain a final subcritical degree measurement result and the uncertainty thereof.

Further preferably, in step 1, the optimization algorithm operation includes the following steps:

for n neutron signal measurement data xi, i, 1,2, …, n measured continuously, m continuous neutron signal measurement data are selected, and the uncertainty of the arithmetic mean of the selected measurement data set is calculated based on an uncertainty analysis model;

changing the starting point and the end point of the selected m continuous neutron signal measurement data to obtain the uncertainty of the arithmetic mean value of all measurement data groups when m is 1,2, …, nAnd selecting a measurement data group with the optimal uncertainty from the measurement data group to serve as an optimal neutron signal measurement value for subsequent subcritical degree measurement analysis.

Further preferably, in the step 2: in the subcritical degree measurement process, if a correction algorithm is adopted to correct the measurement result, determining the uncertainty limit range of a correction factor based on the neutron signal uncertainty obtained in the step 1; when the physical quantity required by correction is calculated, the calculation uncertainty of each physical quantity is controlled, so that the synthetic uncertainty of the correction factor meets the requirement;

further preferably, in the step 2: when the physical quantity required by correction is calculated, the calculation uncertainty of each physical quantity cannot reach the set minimum value, and the synthetic uncertainty of the correction factor cannot meet the requirement, the correction factor and the uncertainty thereof are directly calculated and used for subsequent subcritical degree analysis.

Further preferably, in the step 2: if no neutron signal measurement result exists when correction calculation is carried out, directly calculating a correction factor, and calculating the uncertainty of the correction factor for subsequent subcritical degree analysis.

The invention has the following advantages and beneficial effects:

1. aiming at the influences of factors such as neutron signal statistical fluctuation, high-voltage ripple fluctuation, amplification factor drift, electromagnetic interference and the like in the subcritical degree measurement process, the invention establishes the reactor subcritical degree measurement method capable of reducing the influences. By adopting a mathematical algorithm based on uncertainty analysis, the uncertainty of neutron signal measurement is reduced, the uncertainty introduced by a correction factor is reduced, various subcritical measurement with reactivity introduced locally or uniformly from shallow to deep is overcome, the defects of the conventional reactor subcritical measurement method are overcome, and the efficiency and the accuracy of reactor subcritical measurement are improved.

2. According to the invention, uncertainty analysis is carried out in the subcritical degree measurement process, measurement data are optimized, and the influence of uncertainty is reduced, so that the measurement efficiency and accuracy are improved. At present, no other unit develops a subcritical degree measurement method based on uncertainty analysis or reports of related patent technologies in China. Therefore, it is necessary to master an autonomous subcritical degree measurement method based on uncertainty analysis according to the difference between the autonomous core and the foreign core, and to provide capability for efficient and accurate measurement of the reactor core subcritical degree.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not used as limitations of the present invention.