Nuclear power plant point source radiation source intensity back-stepping method and point source radiation source intensity back-stepping system

Abstract

The invention discloses a nuclear power plant point source radiation source intensity back-stepping method and a point source radiation source intensity back-stepping system. According to the method, dosage rates of multiple positions are acquired through detectors, a normalization radiation source intensity is dispersed in space, a ray tracking method is utilized to calculate an optical distance, equation set coefficient calculation is developed in combination with the material and accumulation factor information, and source intensity is back-stepped; dosage rate calculation is carried out for the positions of the detectors, linear regression analysis is carried out through measurement values and calculation values, key parameters such as standard deviation, gradient and intercept are acquired through calculation, and a quality factor is calculated to measure an acceptable degree of each calculation result; a weight iteration method is further proposed, errors caused by the detectors with relatively large uncertainties are reduced, the previous steps are repeated through utilizing an iteration mode till the quality factor reaches a preset constant value, and the expected radiation source intensity information is acquired.

Description

technical field [0001] The invention relates to a calculation method and system for radiation source intensity in a nuclear power plant, in particular to a point source radiation source intensity inversion method and a point source radiation source intensity inversion system for a nuclear power plant. 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 th...

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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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