Inverse method for surface source radiation source strength in nuclear power plant and surface source radiation source intensity inversion system

Abstract

The invention discloses a nuclear power plant non point source radiation source intensity backstepping method and a non point source radiation source intensity backstepping system. In the nuclear power plant non point source radiation source intensity backstepping method, the dosage rate of a plurality of positions is obtained through detectors, normalized radiation source intensity is dispersed in space, the optical distance is worked out by means of a ray tracing method, the coefficient of the equation set is calculated by combining information of materials and build-up factors and the like, the source intensity is backstepped, then the dosage rate of the detector positions is calculated, the measured value and the calculated value are subjected to linear-regression analysis, key parameters of the standard deviation, the slope, the intercept and the like are calculated, and furthermore the quality factor is calculated to evaluate the acceptance level of each calculating result . a weighted iteration method is provided at the same time, the error introduced by the detector with relatively-high uncertainty is reduced, the above steps are repeated for many times by means of an iteration manner until the quality factor reaches a preset value, and the expected radiation source intensity information is obtained.

Description

technical field [0001] The invention relates to a method and a system for calculating radiation source intensity in a nuclear power plant, in particular to a nuclear power plant area source radiation source intensity inversion method and an area source radiation source intensity inversion system. Background technique [0002] The radioactivity in nuclear power plants comes from the active area of ​​the fuel assembly in the pressure vessel, and the radiation source is mainly composed of fission products, actinides and corrosion activation products. During the operation of the system, the radiation source flows with the coolant through the main system of the primary circuit (including pressure vessels, main pumps, voltage stabilizers, main pipelines, etc.), the chemical container control system, etc., and the radiation sources are distributed on the surface of the coolant and related equipment. The radiation source itself is highly radioactive, and the dose received by the sta...

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Problems solved by technology

[0003] The distribution of radiation sources in nuclear power plants is relatively wide, especially after long-term use and overhaul, it is more and more difficult to infer the radiation intensity of radiation sources at various positions based on engineering experience, so when calculating many data, especially based on radiation source In the calculation of intensity, the accuracy and practicability are greatly affected because it is difficult to obtain accurate basic information. At the same time, the current domestic protective facilities and means are not very complete, which also greatly increases the risk of workers being exposed

[0004] In the prior art, when it is necessary to estimate the radiation source intensity, the source term analysis method is generally used. First, according to the production and disappearance pathways of radioactive substances, its production items (such as inflow items, decay production items, etc.) and disappearance items (such as filter items) are determined. , leakage items, etc.), and define the physical models of each item, then establish nucleon concentration balance equations (groups) for radioactive substances according to the above items, and finally solve the simultaneous equations (groups), but there are a lot of simplifications in these calculations and approximate calculation, so the result is often far from the real value, and there are many obstacles in practical application. In addition, considering the harm caused by the radiation source itself to the human body, the complex geometric structure inside the nuclear power plant, and the accuracy of radionuclides When the information is difficult to obtain, the uncertainty of the nuclear power plant detector measurement value and other factors, the above methods have problems in terms of safety and accuracy, and it is urgent to improve or propose a new way to obtain the intensity of radiation sources

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