阅读说明：本技术 一种基于非破坏性γ能谱法的核材料滞留量分析方法 (Nuclear material retention analysis method based on nondestructive gamma spectrometry ) 是由 何丽霞 卢文广 王思佳 司宇 于 2020-03-31 设计创作，主要内容包括：本发明公开了一种基于非破坏性(NDA)γ能谱法的核材料滞留量分析方法。所述方法根据核材料滞留区域的几何形状、测量设备配置及工作条件将滞留的核材料等效简化为放射性点源、线源或面源；建立点源工作模型、线源工作模型或面源工作模型；利用标准点源、标准线源、标准面源,获取点源工作模型、线源工作模型、面源工作模型的校准系数；利用探测器测量沉积区滞留的核材料,得到其特征γ射线的能峰面积,经校正计算后求得核材料滞留量。本发明所提供的方法具有NDA技术快速便捷的特点,可同时分析多种元素及其同位素含量,为核材料闭合衡算、核设施安全运行、生产效能评价以及退役治理提供数据。(The invention discloses a nuclear material retention analysis method based on a non-destructive (NDA) gamma energy spectrum method. The method equivalently simplifies the detained nuclear material into a radioactive point source, a line source or a plane source according to the geometric shape of a nuclear material detention area, the configuration of measuring equipment and working conditions; establishing a point source working model, a line source working model or a surface source working model; acquiring calibration coefficients of a point source working model, a line source working model and a surface source working model by using a standard point source, a standard line source and a standard surface source; and measuring the nuclear material retained in the deposition area by using a detector to obtain the energy peak area of the characteristic gamma rays, and calculating the nuclear material retention after correction. The method provided by the invention has the characteristic of rapidness and convenience of NDA technology, can simultaneously analyze the content of various elements and isotopes thereof, and provides data for nuclear material closing balance, nuclear facility safe operation, production efficiency evaluation and retirement treatment.)

1. A method for nuclear material retention analysis based on non-destructive gamma spectroscopy, said method comprising the steps of:

step (1), equivalently simplifying the detained nuclear material into a radioactive point source, a line source or a surface source according to the geometric shape of a nuclear material detention area, the configuration of measuring equipment and working condition parameters;

establishing a point source working model, a line source working model or a surface source working model, and determining the relation between the radioactivity of a radioactive point source, a line source or a surface source and the energy peak area of the characteristic gamma rays obtained by a detector;

step (3), utilizing a standard point source, a standard line source and a standard surface source to obtain calibration coefficients of a point source working model, a line source working model and a surface source working model;

and (4) measuring the nuclear material retained in the deposition area by using measuring equipment to obtain the energy peak area of the characteristic gamma ray, calibrating the energy peak area by using the calibration coefficient obtained in the step (3) and substituting the calibrated energy peak area into the working model established in the step (2) to obtain the nuclear material retention.

2. The method for analyzing the nuclear material retention based on nondestructive gamma spectroscopy according to claim 1, wherein in the step (2), the calculation formula of the nuclear material retention in the point source working model is as follows:

m＝K_p×C×d²；

wherein m is the core material retention, g;

c is the energy peak area of the characteristic gamma ray;

d is the distance between the retained nuclear material and the detector;

K_Pthe calibration coefficients of the radioactive point source model.

3. The method for analyzing nuclear material retention based on nondestructive gamma spectroscopy according to claim 2, wherein the calculation formula of the calibration coefficient of the radioactive point source model is:

wherein m is_sIs the amount of the standard point source, g;

C_sthe energy peak area of the gamma ray which is the characteristic of a standard point source;

d₀is the distance between the standard point source and the detector.

4. The method for analyzing nuclear material retention based on nondestructive gamma spectrometry according to claim 1, wherein in step (2), the calculation formula of nuclear material retention in the line source working model is:

λ＝K_L×C×d；

wherein λ is a retention of the core material per unit length, g/cm;

K_Lcalibrating coefficients for the line source;

c is the energy peak area of the characteristic gamma ray;

d is the distance between the retained nuclear material and the detector.

5. The method for analyzing nuclear material retention based on nondestructive gamma spectroscopy according to claim 4, wherein the calculation formula of the calibration coefficient of the radioactive ray source model is:

wherein ms is the amount of the standard point source, g;

cs is the energy peak area of the characteristic gamma ray of the standard line source;

d₀is the distance between the standard line source and the detector;

l is the equivalent length of the radial response of the detector, and has a correlation with the size of the collimator.

6. The method for analyzing the nuclear material retention based on the nondestructive gamma spectroscopy according to claim 1, wherein in the step (2), the calculation formula of the nuclear material retention in the surface source working model is as follows:

ρ＝K_A×C

wherein ρ is a retention per unit area, g/cm²；

K_AThe surface source calibration coefficient is obtained;

c is the energy peak area of the characteristic gamma ray.

7. The method for analyzing nuclear material retention based on nondestructive gamma spectroscopy of claim 6, wherein the calculation formula of the calibration coefficient of the radioactive area source model is:

wherein m is_sIs the amount of standard flour source, g;

cs is the energy peak area of the characteristic gamma ray of the standard surface source;

and A is the response radius of the detector.

8. The method of claim 1, wherein the radioactive point source model is applied to a filter, a glove box, or a pump head under remote conditions.

9. The method for analyzing nuclear material retention based on nondestructive gamma spectrometry according to claim 1, wherein the radioactive ray source model is applied to a linear deposition object.

10. The method for analyzing the nuclear material retention based on nondestructive gamma spectroscopy according to claim 1, wherein the radioactive area source model is applied to a glove box bottom surface, a factory floor and a square pipeline.

Technical Field

The invention relates to the field of nuclear material measurement and analysis, in particular to a nuclear material retention analysis method based on a nondestructive gamma energy spectrum method.

Background

The nuclear material retention has two meanings, one of which is the nuclear material deposition remaining in process equipment, connecting pipes, filters and other working areas after the nuclear facility stops running; the second is the amount of nuclear material loaded in the production process flow of the running nuclear facility, which may also be referred to as process inventory.

A non-destructive (NDA) gamma spectrum analysis method features that the gamma ray emitted from the object is measured to obtain gamma spectrum and the contents of nuclear material and radioactive isotope in it are analyzed without changing the physical state, chemical composition and characteristics of the object. Nuclear materials are radioactive and toxic, and in order to prevent the nuclear materials from being lost and leaked, numerous and complicated pipelines and a large number of equipment containers in facilities are in a strict sealing state, and the retention amount can only be measured and analyzed in situ, in a nondestructive manner and on line by adopting an NDA (non-dispersive analysis) technology.

In the production and operation process of nuclear facilities, the retention phenomenon of nuclear materials is common, the related equipment is numerous in quantity and various in form, the item forms are various, the components are complex, the retention amount is randomly distributed in the equipment, the coverage range and the physical thickness are different, even if the retention amount of the nuclear materials of independent single points is small, after the retention amount is multiplied by the retention range, the length, the area and other parameters, the total retention amount in the process flow is a considerable amount, and the method is an important basis for the safe operation and the production efficiency evaluation of the nuclear facilities and is important data for closed balance calculation. The Nondestructive (NDA) gamma energy spectrum analysis method is applied to measurement and analysis of nuclear material retention, and the technology is promoted to modularization and standardization, so that the method has important significance for nuclear material closing balance, nuclear facility safe operation, production efficiency evaluation and retirement treatment.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a generalized nuclear material retention analysis method based on a nondestructive gamma energy spectrum method, which applies the nondestructive gamma energy spectrum analysis method to the measurement and analysis of nuclear material retention and can provide reference data for nuclear material closing balance, nuclear facility safe operation, production efficiency evaluation and retirement treatment.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for nuclear material retention analysis based on non-destructive gamma spectroscopy, further comprising the steps of:

step (1), equivalently simplifying the detained nuclear material into a radioactive point source, a line source or a surface source according to the geometric shape of a nuclear material detention area, measurement equipment parameters and working condition parameters;

establishing a point source working model, a line source working model or a surface source working model, and determining the relation between the radioactivity of a radioactive point source, a line source or a surface source and the energy peak area of the characteristic gamma rays obtained by a detector;

step (3), utilizing a standard point source, a standard line source and a standard surface source to obtain calibration coefficients of a point source working model, a line source working model and a surface source working model;

and (4) measuring the nuclear material retained in the deposition area by using a detector to obtain the energy peak area of the characteristic gamma ray, calibrating the energy peak area by using the calibration coefficient of the step (3) and substituting the energy peak area of the characteristic gamma ray obtained by measurement into the working model established in the step (2) to obtain the nuclear material retention.

Further, in the step (2), in the point source working model, a calculation formula of the nuclear material retention amount is as follows:

m＝Kp×C×d²；

wherein m is the core material retention, g;

c is the energy peak area of the characteristic gamma ray;

d is the distance between the retained nuclear material and the detector;

KP is the calibration coefficient of the radioactive point source model.

Further, the calculation formula of the calibration coefficient of the radioactive point source model is as follows:

wherein m is_sIs the amount of the standard point source, g;

C_sthe energy peak area of the gamma ray which is the characteristic of a standard point source;

d₀is the distance between the standard point source and the detector.

Further, in the step (2), in the line source working model, the calculation formula of the nuclear material retention amount is as follows:

λ＝K_L×C×d；

wherein λ is a retention of the core material per unit length, g/cm;

K_Lcalibrating coefficients for the line source;

c is the energy peak area of the characteristic gamma ray;

d is the distance between the retained nuclear material and the detector.

Further, the calculation formula of the calibration coefficient of the radioactive ray source model is as follows:

wherein m is_sIs the amount of the standard point source, g;

C_sis the energy peak area of the characteristic gamma ray of the standard line source;

d₀is the distance between the standard line source and the detector;

l is the equivalent length of the radial response of the detector, and has a correlation with the size of the collimator.

Further, in the step (2), in the surface source working model, a calculation formula of the nuclear material retention amount is as follows:

ρ＝K_A×C

wherein ρ is a retention per unit area, g/cm²；

K_AThe surface source calibration coefficient is obtained;

c is the energy peak area of the characteristic gamma ray;

further, the calculation formula of the calibration coefficient of the radioactive area source model is as follows:

wherein ms is the amount of the standard non-point source, g;

cs is the energy peak area of the characteristic gamma ray of the standard surface source;

and A is the response radius of the detector.

Furthermore, the radioactive point source model is suitable for filters, glove boxes and pump heads under remote conditions.

Further, the radioactive ray source model is suitable for a linear deposition object.

Furthermore, the radioactive area source model is suitable for the bottom surface of a glove box, the ground of a factory and a square pipeline.

The invention has the beneficial effects that:

(1) the invention quantitatively analyzes the retention of nuclear material production facilities, and advances the technology to modularization and standardization, and the retention of the nuclear material retained in process equipment, connecting pipelines, filters and other working areas can be obtained after the facilities stop running; in the process of facility operation, the amount of nuclear material loaded in the process flow can be obtained in near real time.

(2) The invention has the characteristic of rapidness and convenience of NDA technology, can simultaneously analyze the contents of various elements and isotopes thereof, and provides data for nuclear material closing balance, nuclear facility safe operation, production efficiency evaluation and retirement treatment.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments thereof.

During measurement, a gamma scintillation detector is used to obtain the energy peak area of the characteristic gamma ray of the nuclear material retained in the item to be measured, and the gamma scintillation detector is actually an energy converter and has the function of converting the detected ray energy into a recordable electric pulse signal. The main components are composed of sodium iodide (thallium) crystal, photomultiplier tube and preamplifier.

Typical nuclear material characteristic gamma ray data are shown in table 1 below:

TABLE 1 measurement of nuclear material retention characteristic gamma ray parameters

According to the geometric shape, the measuring equipment and the working conditions of the item to be measured, the most common nuclear material retention is equivalently simplified into a radioactive point source, a line source and a surface source.