阅读说明：本技术 一种核反应堆外推临界方法 (Nuclear reactor extrapolation method ) 是由 汪文聪 刘才学 黄礼渊 闫晓 踪训成 张永林 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种核反应堆外推临界方法,包括以下步骤：对于每一步外推临界过程,实时采集测量信号；通过不确定度分析方法获得实时采集的测量信号的测量不确定度,直至测量不确定度满足要求,停止采集测量信号,对满足不确定度要求的测量信号进行相应的处理分析,用于外推临界；结合上述满足不确定度要求的测量信号,通过外推临界方法进行外推临界,获得外推结果；采用不确定度分析方法,对外推结果进行不确定度分析,获得外推结果的不确定度；评估外推临界结果的可靠性获得推荐的外推结果及其不确定度。本发明针对核反应堆提棒外推临界过程,弥补现有核反应堆外推临界方法的不足,提高核反应堆外推临界的效率及准确性。(The invention discloses a nuclear reactor extrapolation method, which comprises the following steps: for each step of the extrapolation critical process, acquiring a measurement signal in real time; obtaining the measurement uncertainty of the measurement signal acquired in real time by an uncertainty analysis method, stopping acquiring the measurement signal until the measurement uncertainty meets the requirement, and performing corresponding processing analysis on the measurement signal meeting the uncertainty requirement for extrapolation criticality; combining the measurement signals meeting the uncertainty requirement, and carrying out extrapolation criticality by an extrapolation criticality method to obtain an extrapolation result; carrying out uncertainty analysis on the extrapolation result by adopting an uncertainty analysis method to obtain uncertainty of the extrapolation result; and evaluating the reliability of the extrapolation critical result to obtain the recommended extrapolation result and the uncertainty thereof. Aiming at the critical process of the rod lifting extrapolation of the nuclear reactor, the method makes up the defects of the conventional critical method of the nuclear reactor extrapolation, and improves the efficiency and the accuracy of the critical extrapolation of the nuclear reactor.)

1. A method of extrapolating criticality for a nuclear reactor, comprising the steps of:

step 1, acquiring a measurement signal in real time for each extrapolation critical process;

step 2, obtaining the measurement uncertainty of the measurement signal acquired in real time through an uncertainty analysis method, stopping acquiring the measurement signal until the measurement uncertainty meets the requirement, and performing corresponding processing analysis on the measurement signal meeting the uncertainty requirement for extrapolation criticality;

step 3, extrapolating the critical result based on the uncertainty

Combining the measurement signals meeting the uncertainty requirement, and carrying out extrapolation criticality by an extrapolation criticality method to obtain an extrapolation result; carrying out uncertainty analysis on the extrapolation result by adopting an uncertainty analysis method to obtain uncertainty of the extrapolation result; and evaluating the reliability of the extrapolation critical result to obtain the recommended extrapolation result and the uncertainty thereof.

2. The nuclear reactor extrapolation criticality method of claim 1 wherein the measurement signals include neutron signals and rod position signals.

3. The method of claim 1, wherein the extrapolated results comprise extrapolated critical rod positions, 1/2 added rod positions.

4. A method of criticality extrapolation for a nuclear reactor as claimed in claim 1 wherein, in step 2, the uncertainty analysis model is as follows:

for each extrapolation threshold process, acquiring real-time measurement signal to obtain measurement signal in unit time, and obtaining n measurement signal values x in a period of time_iWherein i is 1,2, …, n; individual measured values x of the measuring signal_iMeasurement uncertainty s (x)_i) Comprises the following steps:

by measuring x by n signals_iArithmetic averaging can be used to obtain an arithmetic mean of such signalsThe uncertainty is:

5. a method of nuclear reactor extrapolation criticality according to claim 1 wherein in step 3, the difference between the extrapolated value and the uncertainty is used as the recommendation.

Technical Field

The invention relates to a nuclear reactor extrapolation method, in particular to a reactor extrapolation method for improving measurement efficiency and accuracy by using uncertainty analysis.

Background

The critical extrapolation test of the reactor is a key test process for obtaining critical rod position data by gradually extracting and extrapolating rods, is an important test item in a physical starting test, and has great significance for the reactor started after the first charging or the material change. Therefore, the critical extrapolation test in the first physical start usually uses two or more critical extrapolation devices to extrapolate simultaneously, extrapolation data is obtained through neutron detector measurement signals arranged at different positions on the periphery of the reactor core, the most conservative test extrapolation value is selected as a reference, and the rod is gradually lifted to approach the critical. The existing critical extrapolation method is based on an active subcritical formula, is widely applied to physical starting tests of various reactor cores, and obtains good results.

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

wherein N is_cFor neutron counting in the detector, for constants related to the detector characteristics, S₀The neutron source is strong, and l is the lifetime of the prompt neutron.

As can be seen from the formula (1), 1/N_cAnd (1-k)_eff) Linear relation, when neutron count of the detector approaches infinity, effective multiplication factor k of the reactor core_effApproaching 1, i.e. the reactor reaches critical.

In the critical extrapolation process, the neutron counting rate measured in each step is a key parameter for the next critical extrapolation, the neutron counting rate is influenced by factors such as statistical fluctuation, high-voltage ripple fluctuation, amplification factor drift and the like in the measurement process, measurement uncertainty exists, and the measurement uncertainty directly acts on a critical extrapolation result. Therefore, it takes a certain time to measure the average of multiple neutron count rates during the extrapolation process. The existing measuring method generally selects a determined measuring time according to experience, measures the average value of neutron counting rates, does not consider the influence of measuring states on the uncertainty of measuring signals, and when the method is used for measuring, the conditions that the uncertainty of measuring signal values of some states is too high and some is too low can occur, so that the measuring efficiency is low, and the uncertainty of the measuring signals can not be guaranteed.

Disclosure of Invention

Aiming at the technical problems: the invention provides a nuclear reactor extrapolation critical method for solving the problems, which adopts a mathematical algorithm based on uncertainty analysis to reduce the measurement uncertainty of parameters such as neutron signals, rod position signals and the like and improve the extrapolation critical efficiency and accuracy.

The invention is realized by the following technical scheme:

a nuclear reactor extrapolated criticality method comprising the steps of:

step 1, acquiring a measurement signal in real time for each extrapolation critical process;

step 2, obtaining the measurement uncertainty of the measurement signal acquired in real time through an uncertainty analysis method, stopping acquiring the measurement signal until the measurement uncertainty meets the requirement, and performing corresponding processing analysis on the measurement signal meeting the uncertainty requirement for extrapolation criticality;

step 3, extrapolating the critical result based on the uncertainty

Combining the measurement signals meeting the uncertainty requirement, and carrying out extrapolation criticality by an extrapolation criticality method to obtain an extrapolation result; carrying out uncertainty analysis on the extrapolation result by adopting an uncertainty analysis method to obtain uncertainty of the extrapolation result; and evaluating the reliability of the extrapolation critical result to obtain the recommended extrapolation result and the uncertainty thereof.

Further preferably, the measurement signal includes a neutron signal and a rod position signal.

Further preferably, the extrapolation includes extrapolating the critical rod position, 1/2 adding the rod position.

Further preferably, in the step 2, the uncertainty analysis model used is as follows:

extrapolating the critical process at each step, and acquiring the measurement signals in unit time for the real-time acquisitionThe measured signal of (2) is obtained n measured signal values x over a period of time_iWherein i is 1,2, …, n; individual measured values x of the measuring signal_iMeasurement uncertainty s (x)_i) Comprises the following steps:

by measuring x by n signals_iArithmetic averaging can be used to obtain an arithmetic mean of such signalsThe uncertainty is:

further preferably, in the step 3, a difference between the extrapolated value and the uncertainty is used as the recommended value.

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 nuclear reactor extrapolation critical process, the invention establishes a nuclear reactor extrapolation critical method capable of reducing the influences; by adopting a mathematical algorithm based on uncertainty analysis, the measurement uncertainty of parameters such as neutron signals, rod position signals and the like is reduced, and the extrapolation critical efficiency and accuracy are improved.

2. Since the uncertainty of the measurement of the neutron count rate during the measurement is inversely proportional to the measurement time, i.e. the longer the measurement time, the lower the uncertainty. But the uncertainty is limited by the test time and cannot be completely eliminated. It is also not possible to extrapolate with measurement data having a higher uncertainty in order to shorten the test time. Therefore, the uncertainty of the measurement signal is analyzed and evaluated in real time, and the measurement is carried out by combining the analysis result, so that the measurement time can be effectively shortened, and the measurement efficiency and accuracy can be improved.

At present, no other unit develops the critical extrapolation method development based on uncertainty analysis or reports of related patent technologies in China. Therefore, it is necessary to master an autonomous critical extrapolation method based on uncertainty analysis for the difference between the autonomous core and the foreign core, and to provide the capability for efficient and accurate critical extrapolation of the core.

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, 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.