阅读说明：本技术 一种取样型液态流出物监测仪的检定方法 (Method for calibrating sampling type liquid effluent monitor ) 是由 连杰 吴平韬 苑磊 黄瑞铭 杨兴荣 刘正山 于 2019-08-29 设计创作，主要内容包括：一种取样型液态流出物监测仪的检定方法,包括以下步骤：步骤一：建立取样容器计算模型；步骤二：建立探测器计算模型；步骤三：放射源参数定义；步骤四：确定标准源探测器效率；步骤五：将取样容器2内空间进行栅元化步骤六：固体点源定义步骤七：算出每个点的点源探测效率步骤八：代表点选择；步骤九：代表点测量。(A method for calibrating a sampling type liquid effluent monitor comprises the following steps: the method comprises the following steps: establishing a sampling container calculation model; step two: establishing a detector calculation model; step three: defining parameters of a radioactive source; step four: determining standard source detector efficiency; step five: and a sixth step of gridding the space in the sampling container 2: and a solid point source defining step seven: calculating the point source detection efficiency of each point: selecting a representative point; step nine: representing point measurements.)

1. A method for calibrating a sampling type liquid effluent monitor comprises the steps that the upper end of a sampling container (2) to be measured is a hollow cylinder, the middle of the sampling container is a measuring hole (4), and the radius of the measuring hole (4) is r₁The lower end of the sampling container (2) is a hemisphere (3) with a radius R₁

The detector (1) is a cylinder body,

The method is characterized in that: the method comprises the following steps:

The method comprises the following steps: establishing a sampling container calculation model; the material M of the sampling container (2) is obtained by measuring and sampling the material quality of the container (2)₁Wall thickness D₁Measuring the dimension r of the hole (4)₁Radius R of the hemisphere (3)₁Internal air volume V₁A physical parameter; establishing a mathematical model of a sampling container;

Mode1∝F₁(M₁,D₁,R₁,r₁,V₁)

Step two: establishing a detector calculation model; obtaining shell material M of detector (1)₂Thickness D of the outer shell₂and the number N of internal circuit boards₂And occupied volume V₂₁、NaI scintillation crystal size V₂₂Size V of photomultiplier tube₂₃Parameters, establishing a detector (1) mathematical model;

Mode2∝F₂(M₂,D₂,N₂,V₂₁,V₂₂,V₂₃)

Step three: defining parameters of a radioactive source; adopting Cs-137 to simulate a radioactive source, and forming liquid source parameter explanation SDEF by calculating the proportion of Cs atoms, H atoms and O atoms in a Cs-137 liquid radioactive source, the shape of a liquid source and the number of radioactive particles₀；

Step four: determining standard source detector efficiency; using the uniform liquid source simulation of the step three to input the models of the step one and the step two to obtain the response efficiency of the primary source of the liquid source of the detector (1) established in the step two under the sampling container established in the step one;

Namely:

E_liquid＝MCNP(Model1,Model2,SDEF₀)

Wherein MCNP represents calculation by using a Monte Carlo calculation method; e_liquidIndicating the primary source response efficiency of the liquid source;

Step five: performing grid element on the space in a sampling container (2), establishing an XYZ coordinate system by taking the circle center O of a measuring hole (4) of the sampling container as an origin, and establishing a test point (xn, yn, zn) every 1cm in the X, Y and Z directions, wherein the test point is defined as a position n, and n is 1,2 and 3;

step six: defining a solid point source; defining a solid point source placed at position 1 as having a radioactive particle count of 10⁷Cs-137 point source of carbon by SDEF₁₁Showing that the solid point source placed at position 2 is defined as a radioactive particle number of 10⁷Cs-137 point source of carbon by SDEF₁₂represents; defining a solid point source placed at position n as having a radioactive particle count of 10⁷Cs-137 point source of carbon by SDEF_1nRepresents;

Step seven: sequentially using a Cs-137 solid point radioactive source SDEF arranged from a position 1 to a position n₁₁～SDEF_1nWriting the substituted liquid source into the Mode1 and the Mode2 in the first step and the second step, and calculating the point source detection efficiency of each point; namely, it is

E_point(xn，yn，zn)＝MCNP(Model1,Model2,SDEF_1n)

After the calculation of all the points in the space of the sampling container 2 is completed, a space efficiency matrix is obtained

Step eight: selecting a representative point; selecting a representative point closest to the primary source response efficiency of the liquid source, i.e. E_point(xn，yn，zn)＝E_liquidAs a representative point, assuming that the point is P (X, Y, Z);

Step nine: a representative point measurement; placing a solid point-shaped radioactive source with the same nuclein as the nuclein in the step six on a position P (X, Y, Z) of a representative point for measurement, and obtaining a net count N of the radioactive source through the current activity A of the radioactive source and the measurement₀Obtaining a detector efficiency E_point-realThe calculation formula is as follows: e_point-real＝(N₀/A)Bq^-1·m³。

2. a method of calibrating a sampled liquid effluent monitor, as claimed in claim 1, wherein: in the first step, a Monte Carlo method is used for establishing a mathematical model of the sampling container.

3. A method of calibrating a sampled liquid effluent monitor, as claimed in claim 1, wherein: in the second step, a mathematical model of the detector 1 is established by using a Monte Carlo method.

4. A method of calibrating a sampled liquid effluent monitor, as claimed in claim 1, wherein: in the third step, the liquid source is in a shape with uniform distribution by default.

5. A method of calibrating a sampled liquid effluent monitor, as claimed in claim 1, wherein: in the fourth step, the Monte Carlo calculation method is used to obtain the response efficiency of the primary source of the liquid source of the detector 1 established in the second step under the sampling vessel established in the first step.

6. A method of calibrating a sampled liquid effluent monitor, as claimed in claim 1, wherein: and seventhly, calculating the point source detection efficiency of each point by using Monte Carlo calculation software.

7. A method of calibrating a sampled liquid effluent monitor, as claimed in claim 1, wherein: in the seventh step, a series of representative points, namely E, which are closest to the response efficiency of the primary source of the liquid source are selected_point(xn，yn，zn)＝E_liquidAs a representative point.

Technical Field

The invention belongs to the field of nuclear power station radioactivity measurement and maintenance, and particularly relates to a method for calibrating a sampling type liquid effluent monitor.

Background

At present, a sampling type total gamma activity monitor is adopted for monitoring liquid effluent of Fuqing nuclear power plants, although a monitoring instrument can give out the concentration of radioactivity activity in liquid discharged from a pipeline in real time, the reliability of the concentration of the radioactivity activity given by a system needs to be further verified. At present, the calibration mode of detectors is that manufacturers generally perform primary source response calibration at the instrument related stage, counting evaluation can be performed only by using a point source in a source inspection hole in the subsequent equipment manufacturing and field use processes, and the consistency and accuracy of each detector cannot be guaranteed.

disclosure of Invention

The invention aims to: a method for testing a representative point sampling type liquid effluent monitor is a method for testing a NaI detector of a sampling type liquid effluent on-line activity monitor, a point-shaped radioactive source is used for testing at a fixed relative position of the detector, the test result can be the same as the primary source response of the detector of the type, and the test result can be written into a measuring device as the primary sensitivity of the detector.

The technical scheme of the invention is as follows: a method for calibrating a sampling-type liquid effluent monitor comprises measuring a hollow cylinder at the upper end of a sampling container, measuring holes at the middle part of the sampling container, and measuring the radius of the measuring holes as r₁The lower end of the sampling container is a hemisphere with a radius of R₁

the detector 1 is a cylinder and is,

The method comprises the following steps:

The method comprises the following steps: establishing a sampling container calculation model; obtaining material M of sampling container by measuring and sampling material of container₁Wall thickness D₁Measuring the hole size r₁Radius of hemisphere R₁Internal air volume V₁A physical parameter; establishing a mathematical model of a sampling container;

Mode1∝F₁(M₁,D₁,R₁,r₁,V₁)

Step two: establishing a detector calculation model; obtaining detector shell material M₂Thickness D of the outer shell₂and the number N of internal circuit boards₂and occupied volume V₂₁NaI scintillation crystal size V₂₂Size V of photomultiplier tube₂₃Parameters, establishmentA detector mathematical model;

Mode2∝F₂(M₂,D₂,N₂,V₂₁,V₂₂,V₂₃)

Step three: defining parameters of a radioactive source; adopting Cs-137 to simulate a radioactive source, and forming liquid source parameter explanation SDEF by calculating the proportion of Cs atoms, H atoms and O atoms in a Cs-137 liquid radioactive source, the shape of a liquid source and the number of radioactive particles₀；

Step four: determining standard source detector efficiency; using the uniform liquid source simulation of the step three to input the models of the step one and the step two to obtain the response efficiency of the primary source of the liquid source of the detector 1 established in the step two under the sampling container established in the step one;

Namely:

E_liquid＝MCNP(Model1,Model2,SDEF₀)

Wherein MCNP represents calculation by using a Monte Carlo calculation method; e_liquidIndicating the primary source response efficiency of the liquid source;

step five: performing grid element on the space in the sampling container 2, establishing an XYZ coordinate system by taking the circle center O of the measuring hole 4 of the sampling container as an origin, and establishing a test point (xn, yn, zn) every 1cm in the three directions of X, Y and Z, wherein the test point is defined as a position n, and n is 1,2 and 3;

Step six: defining a solid point source; defining a solid point source placed at position 1 as having a radioactive particle count of 10⁷Cs-137 point source of carbon by SDEF₁₁Showing that the solid point source placed at position 2 is defined as a radioactive particle number of 10⁷cs-137 point source of carbon by SDEF₁₂Represents; defining a solid point source placed at position n as having a radioactive particle count of 10⁷Cs-137 point source of carbon by SDEF_1nrepresents;

step seven: sequentially using a Cs-137 solid point radioactive source SDEF arranged from a position 1 to a position n₁₁～SDEF_1nWriting the substituted liquid source into the Mode1 and the Mode2 in the first step and the second step, and calculating the point source detection efficiency of each point; namely, it is

E_point(xn，yn，zn)＝MCNP(Model1，Model2，SDEF_1n)

After the calculation of all the points in the space of the sampling container 2 is completed, a space efficiency matrix is obtained

Step eight: selecting a representative point; selecting a representative point closest to the primary source response efficiency of the liquid source, i.e. E_point(xn，yn，zn)＝E_liquidAs a representative point, assuming that the point is P (X, Y, Z);

Step nine: a representative point measurement; placing a solid point-shaped radioactive source with the same nuclein as the nuclein in the step six on a position P (X, Y, Z) of a representative point for measurement, and obtaining a net count N of the radioactive source through the current activity A of the radioactive source and the measurement₀obtaining a detector efficiency E_point-realthe calculation formula is as follows: e_point-real＝(N₀/A)Bq^-1·m³。

In the first step, a Monte Carlo method is used for establishing a mathematical model of the sampling container.

And in the second step, a mathematical model of the detector is established by using a Monte Carlo method.

In the third step, the liquid source is in a shape with uniform distribution by default.

In the fourth step, the Monte Carlo calculation method is used to obtain the response efficiency of the primary source of the liquid source of the detector established in the second step under the sampling container established in the first step.

And seventhly, calculating the point source detection efficiency of each point by using Monte Carlo calculation software.

In the seventh step, a series of representative points, namely E, which are closest to the response efficiency of the primary source of the liquid source are selected_point(xn，yn，zn)＝E_liquidas a representative point.

The invention has the following remarkable effects: once calculation and long-term use. Because the cavity of the Marlin cup detector is fixed by the sampling type liquid effluent monitor adopted on site, the representative point can be used for the verification work of all instruments of the same type after one-time calculation;

the monitoring of effluent is more transparent and standard, actual measurement and comparison can not be carried out on the detector due to inconsistent sensitivity caused by the component problems of factory processing in the prior field use process, primary source calibration can be executed after the representative point is used, and a calibration certificate can be issued according to the calibration result.

Drawings

FIG. 1 is a schematic view of a sampling type liquid effluent monitor

FIG. 2 is a schematic view of a sampling vessel

in the figure: the device comprises a detector 1, a sampling container 2, a hemisphere 3 and a measuring hole 4.

Detailed Description

A method for calibrating a sampling type liquid effluent monitor comprises the following steps.

The upper end of the sampling container 2 to be measured is a hollow cylinder, the middle part is a measuring hole 4, and the radius of the measuring hole 4 is r₁The lower end of the sampling container 2 is a hemisphere 3 with a radius R₁

The detector 1 is a cylinder and is,

The method comprises the following steps: establishing a sampling container calculation model; obtaining the material M of the sampling vessel 2 by measuring and sampling the material quality of the vessel 2₁Wall thickness D₁measuring the size r of the hole 4₁Hemisphere 3 radius R₁Internal air volume V₁a physical parameter. Establishing a mathematical model of the sampling container by using a Monte Carlo method;

Mode1∝F₁(M₁，D₁，R₁，r₁，V₁)

Step two: and establishing a detector calculation model. Obtaining shell material M of detector 1₂thickness D of the outer shell₂And the number N of internal circuit boards₂And occupied volume V₂₁NaI scintillation crystal size V₂₂size V of photomultiplier tube₂₃Establishing a detector 1 mathematical model by using a Monte Carlo method;

Mode2∝F₂(M₂,D₂,N₂,V₂₁,V₂₂,V₂₃)

step three: and (4) defining parameters of a radioactive source. Adopting Cs-137 to simulate a radioactive source, and forming liquid source parameter explanation SDEF (SDEF) by calculating the proportion of Cs atoms, H atoms and O atoms in a Cs-137 liquid radioactive source, the shape of a liquid source (uniform distribution is defaulted) and the number of radioactive particles₀；

step four: standard source detector efficiency is determined. Using the uniform liquid source simulation of the step three to input the models of the step one and the step two, and using a Monte Carlo calculation method to obtain the liquid source primary source response efficiency of the detector 1 established in the step two under the sampling container established in the step one;

Namely:

E_liquid＝MCNP(Model1,Model2,SDEF₀)

wherein MCNP represents calculation by using a Monte Carlo calculation method; e_liquidindicating the primary source response efficiency of the liquid source;

Step five: performing grid formation on the space in a sampling container 2 (as shown in fig. 2), establishing an XYZ coordinate system by taking the center O of a measuring hole 4 of the sampling container as an origin, and setting a test point (xn, yn, zn) every 1cm in three directions of X, Y and Z, wherein n is 1,2 and 3);

Step six: defining a solid point source; defining a solid point source placed at position 1 as having a radioactive particle count of 10⁷cs-137 point source of carbon by SDEF₁₁Showing that the solid point source placed at position 2 is defined as a radioactive particle number of 10⁷Cs-137 point source of carbon by SDEF₁₂Represents; defining a solid point source placed at position n as having a radioactive particle count of 10⁷Cs-137 point source of carbon by SDEF_1nRepresents;

Step seven: sequentially using a Cs-137 solid point radioactive source SDEF arranged from a position 1 to a position n₁₁～SDEF_1nWriting the substituted liquid source into the Mode1 and the Mode2 in the first step and the second step, and calculating the point source detection efficiency of each point by using Monte Carlo calculation software; namely, it is

E_point(xn，yn，zn)＝MCNP(Model1，Model2，SDEF_1n)

after the calculation of all the points in the space of the sampling container 2 is completed, a space efficiency matrix is obtained

step eight: and selecting representative points. Selecting a representative point closest to the primary source response efficiency of the liquid source, i.e. E_point(xn，yn，zn)＝E_liquidAs a representative point, assuming that the point is P (X, Y, Z);

Step nine: representing point measurements. Placing a solid point-shaped radioactive source with the same nuclein as the nuclein in the step six on a position P (X, Y, Z) of a representative point for measurement, and obtaining a net count N of the radioactive source through the current activity A of the radioactive source and the measurement₀Obtaining a detector efficiency E_point-realThe calculation formula is as follows: e_point-real＝(N₀/A)Bq^-1·m³。