CN107783174B - Method for calibrating detection efficiency of nuclear facility liquid effluent on-line monitor - Google Patents
Method for calibrating detection efficiency of nuclear facility liquid effluent on-line monitor Download PDFInfo
- Publication number
- CN107783174B CN107783174B CN201610723965.2A CN201610723965A CN107783174B CN 107783174 B CN107783174 B CN 107783174B CN 201610723965 A CN201610723965 A CN 201610723965A CN 107783174 B CN107783174 B CN 107783174B
- Authority
- CN
- China
- Prior art keywords
- detection efficiency
- detector
- point source
- sample
- calibrating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T7/00—Details of radiation-measuring instruments
- G01T7/005—Details of radiation-measuring instruments calibration techniques
Abstract
The invention relates to a method for calibrating the detection efficiency of a nuclear facility liquid effluent on-line monitor. Then, the Monte Carlo program is utilized to simulate the detection efficiency of the detector on the liquid sample under the actual condition, the attenuation factor can be calculated by combining the detection efficiency of the detector on the liquid sample under the air equivalent condition of simulation calculation, and the detection efficiency of the detector can be finally obtained by combining the measurement result of the standard point source and the attenuation factor of the simulation calculation in the experiment, namely, the efficiency calibration is realized. The method does not need a radioactive solution circulating system, reduces the cost, and simultaneously avoids the steps of preparation, transportation, source guiding and the like of a liquid source; the whole implementation process of the method only needs to measure the standard point source, the standard point source is verified by a national first-level metering standard device, and the calibration result can be traced to the relevant national standard.
Description
Technical Field
The invention relates to a detector efficiency calibration technology in radiation measurement, in particular to a method for economically and rapidly determining the detection efficiency of a non-intrusive liquid effluent on-line monitor.
Background
Liquid effluents are radioactive substances which are discharged into the environment in practice in liquid form. Residents and other living beings surrounding a nuclear facility are exposed to radiation from the radionuclides in the liquid effluent. In order to protect the environment and the health of workers and the public, the radioactive liquid effluents discharged by nuclear power plants and spent fuel reprocessing plants need to be monitored, and the monitoring method is divided into off-line monitoring and on-line monitoring. The online monitoring is divided into a sampling type and a non-intervention type, the non-intervention type online monitor is characterized in that a detector is placed on one side of an effluent discharge pipeline, lead shielding is carried out on the periphery of the effluent discharge pipeline, and real-time information of the activity concentration of the radioactive nuclide in the pipeline is obtained by analyzing the map information of a detector spectrometer. Determining the detection efficiency of a measurement system is a prerequisite for its measurement results to be accurate and reliable.
The primary method for calibrating the spectrometer is to manufacture a radioactive solution circulating system, so that the size and the material of a pipeline of the circulating system are the same as those of the pipeline on site, the flow rate of liquid in the pipeline is consistent, and the shielding effect is consistent. This method has the advantages of being accurate and reliable, but is costly, and requires laboratory implementation, transport of the probe, and complex operation.
The Monte Carlo method can also be used for the efficiency calculation of the spectrometer, and has the characteristics of low cost, high speed and the like. However, since manufacturers generally keep parameters such as probe size secret, the actual parameters are different from the parameters of manufacturers, which greatly increases the error of the result of the passive efficiency calibration method. And the passive efficiency calibration method cannot trace to the relevant national standards.
Disclosure of Invention
The invention aims to establish a method which has high speed and reliable result and can ensure the value tracing.
The invention provides a method for realizing the field calibration of a nuclear facility liquid effluent on-line measurement spectrometer by utilizing a plurality of single nuclide gamma standard point sources and searching for a representative point by means of Monte Carlo simulation. The method does not need a radioactive solution circulating system, reduces the cost, and simultaneously avoids the steps of preparation, transportation, source guiding and the like of a liquid source; the whole implementation process of the method only needs to measure the standard point source, the standard point source is verified by a national first-level metering standard device, and the calibration result can be traced to the relevant national standard.
The technical scheme of the invention is as follows:
the method comprises the steps of firstly, utilizing a Monte Carlo program to respectively calculate the detection efficiency of a detector to a sample under the condition that the sample is air and the detection efficiency of the detector to a point source at each position in a sample space, and obtaining a so-called representative point position coordinate according to the calculation. The representative point has the following characteristics: the detector's detection efficiency for a point source located at this point is minimally different from the detection efficiency of the detector for the sample in the air case over the gamma ray energy range of interest.
And placing the gamma standard point source which is calibrated by the national first-level metering standard device at the representative point, and measuring the detection efficiency of the detector on the standard point source. The nuclide of the selected standard point source requires that its radioactive gamma rays have an energy range that covers the energy range of the gamma rays emitted by the radionuclide in the effluent.
Furthermore, the Monte Carlo program is utilized to simulate the detection efficiency of the detector on the liquid sample under the actual situation, the attenuation factor can be calculated by combining the detection efficiency of the detector on the liquid sample under the air equivalent situation of the simulation calculation, and the detection efficiency of the detector can be finally obtained by combining the measurement result of the standard point source and the attenuation factor of the simulation calculation in the experiment, namely the efficiency calibration is realized.
The invention not only ensures that the calibration result value can be traced to the national first-level metering standard, but also does not need to use a standard liquid source, thereby avoiding a plurality of problems possibly faced in the use process of the liquid source. The method greatly offsets the error caused by the inconsistency of the probe size result and the true value, so that the final calibration result is far more accurate than the result of directly calculating the detection efficiency by using the Monte Carlo simulation.
Drawings
FIG. 1 is a flow chart of the calibration method for the detection efficiency of the on-line monitoring instrument for the liquid effluent of the nuclear facility.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
As shown in FIG. 1, the specific implementation process of the present invention is divided into the following steps:
(1) directly utilizing the size parameters provided by a detector manufacturer to establish a Monte Carlo model of the probe;
then, Monte Carlo software is utilized to calculate the detection efficiency of the detector in the space range of the sample under the condition that the air medium is in the pipeline, and the detection efficiency is recorded as epsilonair，MC(Ei). Where the subscript air indicates that the medium in the pipe is air, hereinafter referred to as the air equivalent, the subscript MC indicates that the value was obtained by monte carlo simulation calculations, Ei indicates gamma rays of different energies, and so on.
Calculating the detection efficiency of a group of detectors on point sources at each position in the sample space by using Monte Carlo software, and recording the detection efficiency as
Where the subscript P denotes the point source.
Representing the position coordinates of the point source. The distance between two adjacent position points in this step is preferably set to 1 mm.
The position coordinates of the representative point are calculated. The calculation method of the position coordinates of the representative point is as the formula (1):
here, the
I.e. detector pair position
A difference function of the detection efficiency of the gas sample under the equivalent condition of the point source and the detector to the air;
is the calculated representative point position.
(2) Placing a gamma standard point source at the position of the representative point, and measuring the detection efficiency of the detector on each energy gamma ray emitted by the point source through experiments, and recording the detection efficiency as
The subscript EX here indicates that the data was obtained experimentally.
(3) On the basis of the step 1, the material composition in the pipeline is set as the actual situation, namely the water body environment, the Monte Carlo program is utilized to calculate the detection efficiency of the detector to the sample, and the efficiency is recorded as epsilontrue，MC(Ei) The subscript true here indicates that the composition of the sample tank wall and the sample gas is consistent with the true case. Calculating an attenuation correction factor according to the efficiency and the efficiency obtained in the step 2:
(4) multiplying the detection efficiency of the detector obtained by the measurement in the step 2 on the point source at the representative point position by the attenuation factor obtained by the calculation in the step 3 to obtain the detection efficiency of the detector on the gas sample, namely the final obtained result of the invention:
the method of the invention and a standard liquid source (as a processing method) are used for calibrating the same monitor under the same environment, experiments show that the relative deviation of the monitor and the standard liquid source is within 7%, in addition, the uncertainty level of the calibration experiment is made, and the expansion uncertainty of the calibration experiment is found to be better than 4% (k is 2), which shows that the representative point method is an accurate and reliable practical method.
The invention is successfully used for calibrating the detection efficiency of a non-intrusive on-line monitor (NaI (Tl)) for liquid effluents of a certain domestic nuclear power station, and the result shows that the conversion factor of the counting rate and the activity concentration is about six times larger, thereby having great significance for practical application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.
Claims (7)
1. A method for calibrating the detection efficiency of an online liquid effluent monitor of a nuclear facility is characterized by comprising the following steps:
(1) respectively calculating the detection efficiency of a detector to the sample and the detection efficiency of the detector to a point source at each position in the sample space under the condition that the sample is air by using a Monte Carlo program, and obtaining a position coordinate of a representative point according to the detection efficiencies;
the solving method of the position coordinates of the representative point in the step (1) is shown as a formula (1):
wherein the content of the first and second substances,
for detector to position
A difference function of the detection efficiency of the gas sample under the equivalent condition of the point source and the detector to the air;
the calculated position of the representative point is obtained; epsilonair，MC(Ei) The detection efficiency of the detector on the sample under the condition that the sample is air;
the detection efficiency of the detector to point sources at each position in the sample space is improved;
(2) placing a gamma standard point source at the representative point, and measuring the detection efficiency of the detector on the gamma standard point source;
(3) simulating the detection efficiency of the detector on the liquid sample under the actual condition by using a Monte Carlo program, and calculating an attenuation factor by combining the detection efficiency of the detector on the sample under the condition that the sample calculated in the step (1) is air;
(4) and (3) combining the measurement result of the gamma standard point source in the step (2) and the attenuation factor of the analog calculation in the step (3) to obtain the detection efficiency of the detector on the gas sample.
2. The method for calibrating the detection efficiency of the on-line nuclear facility liquid effluent monitor as claimed in claim 1, wherein the method comprises the following steps:
the so-called representative points in step (1) have the following characteristics: the detector's detection efficiency for a point source located at this point is minimally different from the detection efficiency of the detector for the sample in the air case over the gamma ray energy range of interest.
3. The method for calibrating the detection efficiency of the on-line nuclear facility liquid effluent monitor as claimed in claim 1, wherein the method comprises the following steps:
and (3) verifying the gamma standard point source in the step (2) by a national first-level metering standard device.
4. The method for calibrating the detection efficiency of the on-line nuclear facility liquid effluent monitor as claimed in claim 1, wherein the method comprises the following steps:
the nuclide of the gamma standard point source requires that the energy range of radioactive gamma rays thereof can cover the energy range of gamma rays emitted by the radioactive nuclide in the effluent.
5. The method for calibrating the detection efficiency of the on-line nuclear facility liquid effluent monitor as claimed in claim 1, wherein the method comprises the following steps:
and (2) setting the distance between two adjacent position points of the point source at each position in the sample space in the step (1) to be 1 mm.
6. The method for calibrating the detection efficiency of the on-line nuclear facility liquid effluent monitor as claimed in claim 1, wherein the method comprises the following steps:
the method for calculating the attenuation correction factor in the step (3) is shown as formula (2):
wherein f isatt(Ei) represents the attenuation correction factor, ∈air，MC(Ei) The detection efficiency of the detector on the sample under the condition that the sample is air; epsilontrue，MC(Ei) And (3) measuring the detection efficiency of the detector on the gamma standard point source when the gamma standard point source is placed at the representative point in the step (2).
7. The method for calibrating the detection efficiency of the on-line nuclear facility liquid effluent monitor as claimed in claim 1, wherein the method comprises the following steps:
the method for calculating the detection efficiency of the detector on the gas sample is obtained by multiplying the measurement result of the gamma standard point source in the step (2) by the attenuation factor obtained by analog calculation in the step (3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610723965.2A CN107783174B (en) | 2016-08-25 | 2016-08-25 | Method for calibrating detection efficiency of nuclear facility liquid effluent on-line monitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610723965.2A CN107783174B (en) | 2016-08-25 | 2016-08-25 | Method for calibrating detection efficiency of nuclear facility liquid effluent on-line monitor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107783174A CN107783174A (en) | 2018-03-09 |
| CN107783174B true CN107783174B (en) | 2021-12-17 |
Family
ID=61438611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610723965.2A Active CN107783174B (en) | 2016-08-25 | 2016-08-25 | Method for calibrating detection efficiency of nuclear facility liquid effluent on-line monitor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107783174B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110515115B (en) * | 2018-05-22 | 2022-11-25 | 中国辐射防护研究院 | Evaluation method for solving peak area of gamma spectrum |
| CN110568472B (en) * | 2019-08-29 | 2022-11-22 | 福建福清核电有限公司 | Method for calibrating sampling type liquid effluent monitor |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103083820A (en) * | 2013-01-13 | 2013-05-08 | 中国科学院合肥物质科学研究院 | Dosage leading and accurately emitting treatment system |
| CN103135125A (en) * | 2011-12-01 | 2013-06-05 | 中国辐射防护研究院 | Energy spectrum analytical method of X-ray filtering reference radiation |
| CN103135122A (en) * | 2011-12-01 | 2013-06-05 | 中国辐射防护研究院 | Mixed nuclide gamma point source volume sample efficiency calibration method |
| CN203025355U (en) * | 2012-12-24 | 2013-06-26 | 核工业北京地质研究院 | Vehicle-mounted gamma-energy-spectrum atmospheric radon eliminating device |
| CN104020483A (en) * | 2014-06-13 | 2014-09-03 | 西北核技术研究所 | Method and device for simulating detection efficiency of calibration detector by adopting virtual source |
| CN104411245A (en) * | 2012-06-29 | 2015-03-11 | 皇家飞利浦有限公司 | Dynamic modeling of imperfections for photon counting detectors |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9504431B2 (en) * | 2013-06-13 | 2016-11-29 | Siemens Medical Solutions Usa, Inc. | Method and apparatus for sensitivity calibration |
| CN103605149B (en) * | 2013-11-26 | 2015-11-25 | 西北核技术研究所 | A kind of device and method of scale xenon sample HPGe detection efficiency |
-
2016
- 2016-08-25 CN CN201610723965.2A patent/CN107783174B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103135125A (en) * | 2011-12-01 | 2013-06-05 | 中国辐射防护研究院 | Energy spectrum analytical method of X-ray filtering reference radiation |
| CN103135122A (en) * | 2011-12-01 | 2013-06-05 | 中国辐射防护研究院 | Mixed nuclide gamma point source volume sample efficiency calibration method |
| CN104411245A (en) * | 2012-06-29 | 2015-03-11 | 皇家飞利浦有限公司 | Dynamic modeling of imperfections for photon counting detectors |
| CN203025355U (en) * | 2012-12-24 | 2013-06-26 | 核工业北京地质研究院 | Vehicle-mounted gamma-energy-spectrum atmospheric radon eliminating device |
| CN103083820A (en) * | 2013-01-13 | 2013-05-08 | 中国科学院合肥物质科学研究院 | Dosage leading and accurately emitting treatment system |
| CN104020483A (en) * | 2014-06-13 | 2014-09-03 | 西北核技术研究所 | Method and device for simulating detection efficiency of calibration detector by adopting virtual source |
Non-Patent Citations (1)
| Title |
|---|
| Determination of Gamma-ray Efficiency Curves for Volume Samples by the Combination of Monte Carlo Simulations and Point Source Calibration;Jun SAEGUSA;《Journal of Nuclear Science and Technology》;20120207;第1076页左栏到1077页左栏，及公式（3） * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107783174A (en) | 2018-03-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3226035A1 (en) | Measurement method for air kerma conventional true value | |
| CN103135122A (en) | Mixed nuclide gamma point source volume sample efficiency calibration method | |
| CN103064101B (en) | Gama scanning measuring method through adoption of asymmetrical standard sample calibration | |
| Smith et al. | Signatures and Methods for the Automated Nondestructive Assay of ${\rm UF} _ {6} $ Cylinders at Uranium Enrichment Plants | |
| CN107783174B (en) | Method for calibrating detection efficiency of nuclear facility liquid effluent on-line monitor | |
| CN104483698A (en) | Xenon source virtual point source scale device and method based on point source efficiency function | |
| Neumaier et al. | EURADOS intercomparisons and the harmonisation of environmental radiation monitoring. | |
| CN104020507B (en) | Active area based on virtual point probe principle determines method | |
| Tarım et al. | Source-to-detector distance dependence of efficiency and energy resolution of a 3" x3" NaI (Tl) detector | |
| CN106896396A (en) | A kind of method for calibrating inert gas outflow thing off-line monitoring instrument detection efficient | |
| JP5523407B2 (en) | Radiation detection apparatus and detection method | |
| Yunos et al. | Reconstruction algorithm of calibration map for RPT techniques in quadrilateral bubble column reactor using MCNPX code | |
| Garger et al. | Prediction of the 137Cs activity concentration in the atmospheric surface layer of the Chernobyl exclusion zone | |
| CN113466915A (en) | Radiation dose rate measuring system and method based on high-purity germanium detector | |
| Rezaie et al. | Studying the response of CR-39 to radon in non-polar liquids above water by Monte Carlo simulation and measurement | |
| Brabants et al. | Minimal detection time for localization of radioactive hot spots in low and elevated background environments using a czt gamma-ray spectrometer | |
| JP6925842B2 (en) | Radioactivity measuring device and radioactivity measuring method | |
| Satoh et al. | Simulation code for estimating external gamma-ray doses from a radioactive plume and contaminated ground using a local-scale atmospheric dispersion model | |
| JP2018044874A (en) | Radiation measuring instrument and radiation measuring method | |
| Alekseev et al. | An investigation into the sensitivity of various albedo neutron dosimeters aimed at correcting the readings | |
| Burson et al. | Simulating energy and angle distributions above infinite plane cobalt-60 sources | |
| JP2018151225A (en) | Measurement system for radioactivity and method for measuring radioactivity | |
| Song et al. | A Study on the Assessment of Source-term for PWR Primary System Using MonteCarlo Code | |
| JP2021196179A (en) | Dose estimation device, method for estimating dose, and dose estimation program | |
| Zhukovsky et al. | Radioactive atmospheric discharges of the European and Russian nuclear power plants |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |