CN112630816A - Method for eliminating or weakening interlayer crosstalk of gamma nondestructive testing system - Google Patents
Method for eliminating or weakening interlayer crosstalk of gamma nondestructive testing system Download PDFInfo
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- CN112630816A CN112630816A CN202011240510.8A CN202011240510A CN112630816A CN 112630816 A CN112630816 A CN 112630816A CN 202011240510 A CN202011240510 A CN 202011240510A CN 112630816 A CN112630816 A CN 112630816A
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- 238000000034 method Methods 0.000 title claims abstract description 21
- 239000011229 interlayer Substances 0.000 title claims abstract description 16
- 238000009659 non-destructive testing Methods 0.000 title claims abstract description 15
- 230000003313 weakening effect Effects 0.000 title abstract description 5
- 239000010410 layer Substances 0.000 claims abstract description 41
- 238000001514 detection method Methods 0.000 claims abstract description 21
- 238000005259 measurement Methods 0.000 claims abstract description 18
- 239000002699 waste material Substances 0.000 claims abstract description 11
- 238000004458 analytical method Methods 0.000 claims abstract description 4
- 230000000875 corresponding effect Effects 0.000 claims description 27
- 230000000694 effects Effects 0.000 claims description 8
- 239000000941 radioactive substance Substances 0.000 claims description 7
- 238000009825 accumulation Methods 0.000 claims description 6
- 238000004364 calculation method Methods 0.000 claims description 6
- 239000002131 composite material Substances 0.000 claims description 3
- 239000012857 radioactive material Substances 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 claims description 3
- 238000012937 correction Methods 0.000 claims description 2
- 238000003904 radioactive pollution Methods 0.000 claims description 2
- 238000013461 design Methods 0.000 abstract description 7
- 238000005516 engineering process Methods 0.000 abstract description 5
- 230000002285 radioactive effect Effects 0.000 abstract description 5
- 238000000053 physical method Methods 0.000 abstract description 3
- 239000002910 solid waste Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000005251 gamma ray Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/167—Measuring radioactive content of objects, e.g. contamination
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/36—Measuring spectral distribution of X-rays or of nuclear radiation spectrometry
Abstract
The invention belongs to the technical field of design and application of a gamma nondestructive testing system based on an SGS (generalized minimum system) technology, and particularly relates to a method for eliminating or weakening interlayer crosstalk of the gamma nondestructive testing system. The shielding collimator of the detector is opposite to the center height of a certain measured layer section of the waste barrel; adjusting the effective field angle of a shielding collimator of the detector to a height position just covering the edge of the scanning layer section, wherein the opening of the shielding collimator of the detector completely covers the radial area of the scanning layer section in the horizontal direction; a measured object contained in an opening angle range of a detector from an opening of a shielding collimator of the detector is taken as a mathematical analysis model, a standard source scale barrel is filled with a pollution-free medium consistent with subsequent detection, and the standard source scale barrel is measured; establishing different measurement models and correcting, determining and storing corresponding detection efficiency; and (4) correcting the measurement result. The invention effectively reduces or eliminates the interlayer radioactive interference by combining the physical method with the method.
Description
Technical Field
The invention belongs to the technical field of design and application of a gamma nondestructive testing system based on an SGS (generalized minimum system) technology, and particularly relates to a method for eliminating or weakening interlayer crosstalk of the gamma nondestructive testing system.
Background
The gamma nondestructive detection system is mainly used for measuring gamma-ray pollution nuclide and specific activity in standard barreled solid waste. The equipment is widely applied to the fields of nuclear facility decommissioning and three-waste treatment so as to realize scientific management and control of radioactive solid wastes. The technical commonality of the equipment of the type adopts SGS (segmented Gamma scanning) technology. From the hardware structure, the equipment mainly comprises a mechanical lifting system, a detector shielding collimator and a mechanical rotary weighing system. The whole measurement of the waste bucket is realized through a layered scanning mode.
One of the important factors affecting the measurement accuracy of this type of equipment is the effect of inter-layer crosstalk, which can contribute more than 30% to measurement errors. In order to effectively weaken or eliminate the stress, physical methods are generally adopted at home and abroad for solving the problem. Namely, the shielding collimator of the detector is designed to be a deeper aperture size, so that the effective measurement field angle of the detector is ensured to just cover the scanned layer section, and the contribution of rays generated by gamma-contaminated nuclides in radioactive substances close to the upper layer section and the lower layer section cannot generate obvious influence and interference on the scanned layer section. The design of a deep detector shielding collimator for the detector is needed, and the problems of detection lower limit of equipment, structural size of a configured spectrometer detector, timeliness and the like need to be considered. In practical application, the method for avoiding the interference influence of the adjacent upper layer and the lower layer through physical design has high specific design difficulty and low application flexibility.
Disclosure of Invention
At present, the number of scanning layer sections of a gamma nondestructive testing system based on an SGS technology, which is commonly used at home and abroad, is relatively fixed, the interlayer radioactive interference is mainly reduced or eliminated in a physical mode, the application flexibility is poor, and in addition, the number of the layer sections cannot be conveniently adjusted. The invention effectively reduces or eliminates the interlayer radioactive interference by combining the physical method with the method.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for eliminating or reducing interlayer crosstalk of a gamma nondestructive testing system,
1. the shielding collimator of the detector is opposite to the center height of a certain measured layer section of the waste barrel;
2. adjusting the effective field angle of a shielding collimator of the detector to a height position just covering the edge of the scanning layer section, wherein the opening of the shielding collimator of the detector completely covers the radial area of the scanning layer section in the horizontal direction;
3. a measured object contained in an opening angle range of a detector from an opening of a shielding collimator of the detector is taken as a mathematical analysis model, a standard source scale barrel is filled with a pollution-free medium consistent with subsequent detection, and the standard source scale barrel is measured;
4. establishing different measurement models and correcting, determining and storing corresponding detection efficiency: using a gamma spectrometer detector to obtain the energy spectrum data of a certain scanning layer of a corresponding standard source scale barrel, and setting the activity of the nuclide corresponding to the standard source in the scanning layer as ASourceThe unit Bq, the corresponding nuclide characteristic energy peak counting rate n1, the corresponding nuclide characteristic energy peak background counting rate n book and the corresponding characteristic energy branch ratio xi are used for calculating the content of radioactive substances in each scanning layer section of a standard source scale barrel, the density distribution of the whole standard scale barrel is uniform, the radioactive pollution distribution is uniform, the detection efficiency eta of the corrected corresponding characteristic energy peak is calculated through a formula A ═ n1-n book)/xi-eta, the detection efficiency of different characteristic energy peaks of the standard source scale barrel is calculated in sequence, and the detection efficiency of each scanning layer at different characteristic energy peaks is calculated for each scanning layerEstablishing and storing a detection efficiency file corresponding to the section so as to be convenient for quick and accurate calling in a later measurement process after efficiency calibration;
5. correction of the measurement results: finishing calculation aiming at each scanning layer section, and finally solving the content of radioactive substances in the waste barrel in an accumulation mode; during the accumulation process, necessary subtraction of overlapping scan segments and repeated calculation of radioactive material content is required.
A certain tested layer section of the waste barrel is 5-10 layers.
The standard source is a composite source or a single source containing a plurality of different characteristic energies, and the nuclide type and the corresponding activity specific activity of the standard source are determined.
The nuclide type is consistent with the source nuclide of the object to be measured, or the characteristic energy peak covers high, medium and low energy sections under the condition of single source.
The characteristic energy peaks are consistent for the same nuclide, and the branch ratio of the characteristic energy peaks is a determined value.
The beneficial effects obtained by the invention are as follows:
(1) the method can flexibly adjust and set the number of scanning layer sections according to the characteristics of the measured object, and is favorable for further improving the flexibility and timeliness of equipment application (optimizing the measurement mode and shortening the measurement time).
(2) The method eliminates or weakens the interference influence of the interlayer radioactivity by combining physics and an algorithm, has flexible application mode and is convenient for specific design.
(3) The method is suitable for structural function design of all gamma nondestructive testing systems based on SGS technology.
Detailed Description
The present invention will be described in detail with reference to specific examples.
The method for eliminating or weakening the interlayer crosstalk of the gamma nondestructive testing system comprises the following steps:
1. the shielding collimator of the detector is over against the center height of a certain tested layer section (generally 5-10 layers) of the waste barrel;
2. adjusting the effective field angle of a shielding collimator of the detector to a height position just covering the edge of the scanning layer section, wherein the opening of the shielding collimator of the detector completely covers the radial area of the scanning layer section in the horizontal direction;
3. the method comprises the steps of taking a measured object contained in an opening angle range of a detector from an opening of a shielding collimator of the detector as a mathematical analysis model, filling a standard source scale barrel with a pollution-free medium consistent with subsequent detection, and measuring the standard source scale barrel. The standard source is generally a composite source or a single source containing a plurality of different characteristic energies, and the nuclide type and the corresponding activity specific activity of the standard source are determined. The nuclide type is recommended to be consistent with the nuclide of the source item of the measured object, or the characteristic energy peak covers high, medium and low energy sections under the condition of a single source, so that a detection efficiency fitting curve completely covering the measurement reference model is formed subsequently.
4. Establishing different measurement models and correcting, determining and storing corresponding detection efficiency. And (3) acquiring the energy spectrum data of a scanning layer of a corresponding standard source scale bucket by using a gamma spectrometer detector configured on the equipment. Setting: the activity of the corresponding nuclide of the standard source in the scanning layer section is ASource(unit Bq), a corresponding nuclide characteristic energy peak counting rate n1, a corresponding nuclide characteristic energy peak background counting rate nberg and a corresponding characteristic energy branch ratio ξ (for the same nuclide, the characteristic energy peaks are consistent, and the branch ratio of the characteristic energy peaks is a determined value). For a standard source scale drum, the radioactive substance content in each scanning layer section can be calculated (the density of the whole standard scale drum is uniformly distributed, and the radioactive contamination is uniformly distributed). The detection efficiency η after the corresponding characteristic energy peak is corrected can be calculated by the formula a ═ n 1-nberg)/ξ η. And sequentially calculating the detection efficiency of different characteristic energy peaks of the standard source scale barrel. And establishing and storing a detection efficiency file corresponding to each scanning layer section so as to facilitate quick and accurate calling in a later measurement process after efficiency calibration.
5. And (4) correcting the measurement result. And (4) finishing calculation aiming at each scanning layer section, and finally solving the content of the radioactive substances in the waste barrel in an accumulation mode. During the accumulation process, necessary subtraction of overlapping scan segments and repeated calculation of radioactive material content is required.
Claims (5)
1. A method for eliminating or reducing interlayer crosstalk of a gamma nondestructive testing system, comprising:
1. the shielding collimator of the detector is opposite to the center height of a certain measured layer section of the waste barrel;
2. adjusting the effective field angle of a shielding collimator of the detector to a height position just covering the edge of the scanning layer section, wherein the opening of the shielding collimator of the detector completely covers the radial area of the scanning layer section in the horizontal direction;
3. a measured object contained in an opening angle range of a detector from an opening of a shielding collimator of the detector is taken as a mathematical analysis model, a standard source scale barrel is filled with a pollution-free medium consistent with subsequent detection, and the standard source scale barrel is measured;
4. establishing different measurement models and correcting, determining and storing corresponding detection efficiency: using a gamma spectrometer detector to obtain the energy spectrum data of a certain scanning layer of a corresponding standard source scale barrel, and setting the activity of the nuclide corresponding to the standard source in the scanning layer as ASourceThe unit Bq, the corresponding nuclide characteristic energy peak counting rate n1, the corresponding nuclide characteristic energy peak background counting rate n, and the corresponding characteristic energy branch ratio xi are used for calculating the content of radioactive substances in each scanning layer section of a standard source scale barrel, the density distribution of the whole standard scale barrel is uniform, the radioactive pollution distribution is uniform, the detection efficiency eta of the corrected corresponding characteristic energy peak is calculated through a formula A (n1-n number)/xi eta, the detection efficiency of different characteristic energy peaks of the standard source scale barrel is calculated in sequence, and a detection efficiency file corresponding to each scanning layer section is established and stored so as to facilitate quick and accurate calling in a later measurement process after efficiency calibration;
5. correction of the measurement results: finishing calculation aiming at each scanning layer section, and finally solving the content of radioactive substances in the waste barrel in an accumulation mode; during the accumulation process, necessary subtraction of overlapping scan segments and repeated calculation of radioactive material content is required.
2. The method for eliminating or reducing interlayer crosstalk of a gamma nondestructive testing system according to claim 1, wherein: a certain tested layer section of the waste barrel is 5-10 layers.
3. The method for eliminating or reducing interlayer crosstalk of a gamma nondestructive testing system according to claim 1, wherein: the standard source is a composite source or a single source containing a plurality of different characteristic energies, and the nuclide type and the corresponding activity specific activity of the standard source are determined.
4. The method for eliminating or reducing interlayer crosstalk of a gamma nondestructive testing system according to claim 3, wherein: the nuclide type is consistent with the source nuclide of the object to be measured, or the characteristic energy peak covers high, medium and low energy sections under the condition of single source.
5. The method for eliminating or reducing interlayer crosstalk of a gamma nondestructive testing system according to claim 1, wherein: the characteristic energy peaks are consistent for the same nuclide, and the branch ratio of the characteristic energy peaks is a determined value.
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| CN202011240510.8A CN112630816A (en) | 2020-11-09 | 2020-11-09 | Method for eliminating or weakening interlayer crosstalk of gamma nondestructive testing system |
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| CN202011240510.8A CN112630816A (en) | 2020-11-09 | 2020-11-09 | Method for eliminating or weakening interlayer crosstalk of gamma nondestructive testing system |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08220238A (en) * | 1995-02-13 | 1996-08-30 | Mitsubishi Heavy Ind Ltd | Nondestructive collimator measuring method for radioactivity of radioactive waste solidified body canned in drum |
| JPH09230051A (en) * | 1996-02-20 | 1997-09-05 | Mitsubishi Heavy Ind Ltd | Radioactivity quantity measuring method for radioactive waste solidified body |
| CN108919331A (en) * | 2018-07-03 | 2018-11-30 | 上海交通大学 | A kind of double detector spiral gamma scanning survey method of pair of radioactive waste bucket |
| CN110887853A (en) * | 2018-09-07 | 2020-03-17 | 四川理工学院 | SGS fault efficiency calibration method for voxel attenuation efficiency weighted average |
-
2020
- 2020-11-09 CN CN202011240510.8A patent/CN112630816A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08220238A (en) * | 1995-02-13 | 1996-08-30 | Mitsubishi Heavy Ind Ltd | Nondestructive collimator measuring method for radioactivity of radioactive waste solidified body canned in drum |
| JPH09230051A (en) * | 1996-02-20 | 1997-09-05 | Mitsubishi Heavy Ind Ltd | Radioactivity quantity measuring method for radioactive waste solidified body |
| CN108919331A (en) * | 2018-07-03 | 2018-11-30 | 上海交通大学 | A kind of double detector spiral gamma scanning survey method of pair of radioactive waste bucket |
| CN110887853A (en) * | 2018-09-07 | 2020-03-17 | 四川理工学院 | SGS fault efficiency calibration method for voxel attenuation efficiency weighted average |
Non-Patent Citations (3)
| Title |
|---|
| 刘宇琦: "中低放射性废物分层γ扫描检测中效率刻度技术研究", 中国优秀硕士学位论文全文数据库 工程科技II辑, no. 10, 15 October 2018 (2018-10-15), pages 16 - 24 * |
| 徐利军 等: "壳源法放射性废物桶作为SGS装置校准源的可行性", 原子能科学技术, vol. 50, no. 3, 31 March 2016 (2016-03-31), pages 558 - 564 * |
| 苏容波: "SGS技术在核设施退役桶装废物测量中的简化与应用", 中国优秀硕士学位论文全文数据库 工程科技II辑, no. 11, pages 12 * |
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