This standard specifies the items, methods, evaluation and quality assurance of radiation health protection monitoring of sealed source instruments. This standard applies to strength measurement instruments containing sealed sources, but not to non-intensity measurement instruments and detection instruments within the exemption scope specified in the national standard GB13367 "Principles for the Management of Exemptions for Radiation Sources and Practices". GBZ 137-2002 Specification for Health Protection Monitoring of Sealed Source Instruments GBZ137-2002 Standard download decompression password: www.bzxz.net

Ics13.100
National occupational health standard of the People's Republic of China GBZ137-2002
Specifications of radiological protection monitoringfor gauges containing sealed radioactive source2002-04-08Promulgated
Ministry of Health of the People's Republic of China
Implementation on 2002-06-01
Normative reference documents
Terms and definitions
Test items and time
Test methods and evaluation
Quality assurance
Appendix A (Normative appendix) Schematic diagram of dose equivalent measurement area outside the source containerAppendix B (Informative appendix) Field monitoring record formatForeword
This standard is formulated in accordance with the "Occupational Disease Prevention and Control Law of the People's Republic of China". From the date of implementation of this standard, the original standard WS/T185-1999 will be invalidated at the same time.
Chapter 4-5 and Appendix A of this standard are mandatory contents, and the rest are recommended contents. This standard is used in conjunction with the national standard GBZ125-2002 "Standard for Health Protection of Sealed Source Instruments". In view of the fact that the applicable temperature, fire resistance, source gate endurance, etc. of sealed radioactive sources and containers containing sealed source instruments have been specified in relevant standards, the detection of these performance indicators can be tested in accordance with the relevant provisions of GB4705 "Classification of Sealed Source Radioactive Sources" and GB14052 "Radiation Safety Performance Requirements for Isotope Instruments Installed on Equipment". This standard stipulates the leakage radiation of the source container of the sealed source instrument under storage and working conditions, the radiation dose equivalent rate of the sealed source instrument installation site, and the detection of sealed source leakage.
Appendix A of this standard is a normative appendix. Appendix B of this standard is an informative appendix. This standard is proposed and managed by the Ministry of Health.
Drafting unit of this standard: Jinzhou Institute of Occupational Disease Prevention and Control. The main drafter of this standard: Liu Xuecheng.
This standard is interpreted by the Ministry of Health.
Specifications for health protection monitoring of instruments containing sealed sources 1 Scope
GBZ 137-2002
This standard specifies the items, methods, evaluation and quality assurance of radiation health protection monitoring of instruments containing sealed sources. This standard applies to intensity measurement instruments containing sealed sources, but does not apply to non-intensity measurement instruments and detection instruments within the scope of exemption specified in the national standard GB13367 "Principles for the Management of Exemptions for Radiation Sources and Practices" 2 Normative references
The clauses in the following standards become clauses of this standard through reference in this standard. For all dated referenced documents, all subsequent amendments (excluding errata) or revised versions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all undated referenced documents, the latest versions shall apply to this standard.
GB4075 Classification of sealed radioactive sources
GB13367 Principles for exemption management of radiation sources and practices GB14052
GBZ125
3 Terms and definitions
Radiation safety performance requirements for isotope instruments installed on equipment Hygienic protection standards for instruments containing sealed sources
The following terms and definitions apply to this standard. 3.1 Gauge containing sealed radioactive source for measuring intensity
An instrument that detects relevant quantities by detecting changes in particle fluence in the presence or absence of the object to be measured or detecting the fluence of secondary particles generated by the interaction between particles and matter, such as level gauges, thickness gauges, density gauges, hygrometers, nuclear scales, etc. 3.2 Type inspection type inspection
Also known as routine inspection, it is a comprehensive inspection of various product indicators to assess whether the product quality meets all standards and design requirements. For mass-produced products, regular sampling is often required to check their quality stability. 3.3 Ex-factory inspection Ex-factory inspection The final inspection that must be carried out on formally produced products before they leave the factory to assess whether the products that have passed the type inspection have the quality confirmed in the type inspection before they leave the factory. Ex-factory inspection with the participation of the ordering party is called delivery inspection. 3.4 Acceptance inspection Check test
Inspection conducted by the user or management department to determine whether the quality of each unit or batch of products submitted by the manufacturer meets the requirements.
3.5 Routine inspection Ordinary test
Inspection conducted by the user or management department at predetermined time intervals at a predetermined location to determine whether the working conditions are suitable for continued operation.
4 Inspection items and time
See Table 1 for the radiation protection performance inspection items for sealed source detection instruments. Table 1 Corresponding standards for test items of radiation protection performance of detection instruments Type inspection Factory inspection Routine inspection Standard clauses Structure and working status index of source container Source gate endurance Maximum and minimum temperatures applicable to source container Fire resistance of source container Label of source container Random documents of instrument Installation place of source container Leakage of source container when source is in storage position Leakage radiation of source container when source is in working position Line and 2.5μSv/h dose area ||Sealed source leakage
5 Detection method and evaluation
Before production
5.1 Inspection of the structure and working status indication of the source containerAfter production
10 cycles of operation
When there are major changes in design, process or materials
Acceptance inspection
Visual inspection
10 cycles of operation
Check the certificate of conformity
Visual inspection
10 cycles of operation
When necessary
Through the disassembly, inspection and analysis of the container without sealed source, the structure of the source container is inspected in combination with the review of drawings. This inspection is only carried out during type inspection. The inspection of the working status indication of the source container adopts visual inspection, which should be carried out during type inspection and acceptance inspection, and the instruments in use shall be inspected at least once a year. The source container is qualified if its structure is safe and reliable and the working status indication is clear and definite. 5.2 Source gate endurance, applicable temperature and fire resistance test of source container 5.2.1 Type inspection
The inspection time is the same as Article 6.4 of GBZ125.
The inspection method is the same as Articles 7.3 to 7.5 of GB14052. The evaluation method is the same as Article 7.2 of GBZ125.
5.2.2 Source gate endurance inspection
The user shall conduct acceptance inspection when purchasing the detection instrument, and the detection instrument in use shall be subject to routine inspection at least once a year. The type inspection of the source gate endurance before production shall be repeated 1000 times continuously; the endurance inspection of other source gates shall be conducted by “opening and closing” the source gate for 10 consecutive actions (this inspection can be combined with daily maintenance, and lubrication measures shall be taken before the inspection). The source gate shall be qualified if it is suitable for “opening and closing”. 5.3
Inspection of the source container's label and instrument's random documents The source container's label must be inspected during type inspection, acceptance inspection, and routine inspection; the instrument's random documents are only inspected during type inspection and acceptance inspection before production. Through visual inspection, observe whether the source container's label content is clear and visible, and whether the label is firmly fixed. The inspection of random documents must comply with the provisions of Article 5.4 of GBZ125. 5.4 Detection of the radiation dose equivalent rate of the source container's leakage radiation Routine inspection shall be carried out at least once a year.
5.4.1 Detection instrument
Select an instrument suitable for the radiation type, energy, and radiation level of the radiation to be measured. The instrument shall meet the following requirements: basic error ≤ 15%; the energy response coefficient of the corresponding radiation to be measured is 1.0 0.4; the minimum readable radiation dose equivalent rate should be 1x10uSv/h.
5.4.2 Detection conditions
Close the source gate of the source container. The inspection site should be spacious and free of debris. Except for the source container to be inspected, the inherent radiation level of the site should be the general environmental background level.
During type inspection and acceptance inspection, the activity of the sealed source in the source container should be the rated activity value. 5.4.3 Inspection points
Determine according to Article 7.3.3 of GBZ125.
5.4.4 Test procedure
a) Preparation before test
Check the power indication of the instrument. Check the indication value of the instrument self-calibration source. Adjust the instrument "zero point", select the detector window suitable for the radiation to be measured, and check and read the instrument "background reading value" in a place far away from the source to be detected. b) Reading
Measure at 5cm and 100cm from the outer surface of the sealed source container respectively. The corresponding distance should be the distance from the center of the sensitive volume of the dose detection instrument detector to the corresponding surface. For the measurement at 5cm from the outer surface, the recorded dose equivalent rate refers to the average reading on an area of ​​10cm2: the measurement of the dose equivalent rate at 100cm from the outer surface refers to the average reading on an area of ​​100cm. For the test at 5cm from the outer surface of the sealed source container, when the geometric center of the detector cannot reach the position to be measured, the detector can be placed close to the corresponding surface for approximate measurement. For the detection of neutron source detection instruments, neutron and gamma radiation meters should be used respectively, and its dose equivalent rate must be the sum of the neutron and accompanying gamma radiation dose equivalent rates.
During the test, the instrument range is adjusted from large to small so that the readout value is between 0.2 and 0.8 of the full scale. The reading should be read after the instrument response time is greater than the stable value, and the reading should be measured point by point as required. Read more than 4 values ​​at each point. 5.4.5 Evaluation
The dose equivalent rate of the measuring point is calculated according to formula (1) from the measured value. (A -A.)
Where: d-measurement point dose equivalent rate:
A.-average measurement value
Ao-base measurement value;
fi-energy response coefficient:
fz-instrument calibration coefficient.
Calculate the instrument calibration coefficient by formula (2).
Where: fz-instrument calibration coefficient;
d.-given dose equivalent rate of the standard source; A-instrument reading value.
Draw a dose area of ​​2.5μSv/h based on the measurement results. (2)
Leakage radiation level: Evaluate the safety performance level of the isotope instrument according to Table 2 in GB14052. 5.5 Radiation level detection at the installation site
Routine inspection shall be carried out at least once a year.
5.5.1 Detection instrument
The minimum readable radiation dose equivalent rate shall be 1×10-2μSv/h, and the other requirements are the same as 5.4.1. 5.5.2 Detection conditions
Measure with the sealed source gate closed and opened. For transmission instruments, the detection can be carried out without the object to be tested: for scattering instruments, the detection should be carried out with the object to be tested. 5.5.3 Detection points
The detection points include: points at 5cm and 100cm from the outer surface of the boundary shown in Appendix A (Normative Appendix): locations with higher expected doses: locations where personnel stay for a longer time: representative points in the room where the instrument is located. Generally, at least 5 points are set in the room where the instrument is located, i.e., points are set in the center and four corners of the room. When measuring, the detector should be located 1m above the ground. When the dose equivalent rate is greater than 25uSv/h at the working position of the personnel, the eyes, chest, gonads, hands and other parts of the corresponding personnel should be measured respectively.
5.5.4 The test procedure is the same as 5.4.4.
5.5.5 Evaluation
The test results shall be judged according to Table 1 of Article 4.8 of GBZ125 to determine whether the location category it has reached is consistent with the actual installation location. When the radiation level exceeds the zoning management level, there shall be zoning (control area, supervision area) control and corresponding zoning management. 5.6 Sealed source leakage test
5.6.1 Factory inspection
After the sealed source is produced and meets the factory conditions, this test shall be carried out before leaving the factory. This test shall be carried out by the sealed source manufacturer according to the method in Appendix E of GB4075. The radioactive contamination detected in each test shall be less than 185Bq. The sealed source sold must have a sealed source leakage inspection certificate, which shall record the inspection method, applicable standards, inspection date, inspector and other items.
5.6.2 Acceptance inspection and routine inspection
During acceptance, the inspector shall check the factory inspection certificate provided by the manufacturer. Routine inspection is carried out indirectly according to the following provisions. a) Inspection time
When the sealed source is suspected of leakage or the source is replaced through some information analysis, the source leakage inspection shall be carried out once a year within the shelf life of the source, and once every six months when the source shelf life is exceeded. b) Inspection method
When replacing the source, the inner surface of the source container can be wiped. Regular inspection during use should wipe the outer area of ​​the source container that is most likely to be contaminated when the sealing performance of the source has an unexpected problem. The wiping area should be no less than 10cm×10cm. When wiping, it should be carried out from left to right or from top to bottom in sequence. The swab sample is measured with a laboratory measuring instrument. The detection limit of the instrument is not more than 2Bg (95% confidence level). It can measure total α or total β surface contamination respectively. c) Evaluation and treatment
When the radioactive contamination of the swab sample is greater than 20Bq, the sealed source should be suspected of leakage and further inspection should be carried out by a qualified unit according to the method specified in GB4075.
When the measured contamination is greater than 185Bq, the sealed source cannot be used any longer and needs to be scrapped and replaced with a new source, and measures should be taken to prevent the spread of radioactive contamination.
6 Quality Assurance
6.1 The testing personnel should have the corresponding professional knowledge of radiation measurement and protection, and can only engage in monitoring work after strict technical training and passing the assessment. bZxz.net
6.2 The radiation instrument used for testing should be calibrated on schedule. 6.3 During the test, the test form in Appendix B (Informative Appendix) should be referred to and records should be carefully made. A review system for test results and reports should be established, and the review should be conducted independently by two persons. The report should be signed by the tester, reporter, and auditor. Appendix A
(Normative Appendix)
Schematic diagram of the dose equivalent measurement area around the source containerA1Schematic diagram of the dose equivalent measurement area around the source container of the detection instrumentSource component
Unit cm
Figure A1Schematic diagram of the dose equivalent rate measurement area around the source container of the density meterUnit: cm
One meter at the best distanceRe-cut measuring head
-1.3cm thick copper screen, its width and length must be at least 5cm larger than the cross-sectional size of the radiation beam100
Figure A2Schematic diagram of the dose equivalent rate measurement area around the source container of the level meterFigure A3
Chain Simple chess batch material
Unit.cm
Product head
β, T Schematic diagram of the dose equivalent rate measurement area outside the backscatter measuring instrument Unit cm
Measurement head
Surface material
Figure A4 Schematic diagram of the dose equivalent rate measurement area outside the backscatter measuring instrument 100
Measurement head
0.6cm Original steel plate
Standard cancer scatterer, its size should be at least 5cm
2cm larger than the cross section of the useful
beam Original polyethylene
Figure A5 Schematic diagram of the dose equivalent rate measurement area outside the backscatter measuring instrument Schematic diagram of dose equivalent rate measurement area A2 When the distance between the probe of the transmission detection instrument and the adjacent surface of the source container is less than, equal to or greater than 10 cm, the equidistant contour line diagram of the dose equivalent rate measurement area outside the source container when the source gate is "open" or "closed" is shown in Figure A6. 100
Source components
A3 Description
Source gate closed
Source components
Source in the open position
Figure A6 Schematic diagram of equidistant contour lines
Each figure is a schematic diagram of a section perpendicular to the long diameter of the object being measured Unit
Name of measuring instrument
Calibration coefficient
Name of the instrument under test
Appendix B
(Informative Appendix)
On-site monitoring record form
Table B1 Sealed source instrument Source container leakage radiation level detection record form Number
License number
Energy response coefficient
Name of sealed source included
Measurement position
(Axis direction)
5cm from the surface of the source container
Radioactivity
Dose equivalent rate
μSv/h
Note: During measurement, the source gate is in the "off" state. Tester:
Reviewer:
Person in charge
Metrology verification number
Installation location
100cm from the surface of the source container
Dose equivalent rate
μSv/h6cm original steel plate
marked cancer scatterer, its size should be at least 5cm larger than the cross section of the useful
beam
2em original polyethylene
Figure A5 Schematic diagram of the dose equivalent rate measurement area around the backscattered neutron measuring instrument A2 When the distance between the probe of the transmission detection instrument and the adjacent surface of the source container is less than, equal to or greater than 10cm, the equidistant contour line diagram of the dose equivalent rate measurement area around the source container when the source gate is "open" or "closed" is shown in Figure A6. 100
Source components
A3 Description
Source gate closed
Source components
Source in the\open position
Figure A6 Schematic diagram of equidistant contour lines
Each figure is a schematic diagram of a section perpendicular to the long diameter of the object being measuredUnit
Name of measuring instrument
Scale factor
Name of instrument being tested
Appendix B
(Informative Appendix)
On-site monitoring record form
Table B1 Sealed source instrument Source container leakage radiation level detection record form Number
License number
Energy response coefficient
Name of sealed source included
Measurement position
(Axis direction)
5 cm from the surface of the source container
Radioactivity
Dose equivalent rate
μSv/h
Note: During measurement, the source gate is in the "off" state. Tester:
Auditor:
Person in charge
Measurement verification number
Installation location
100cm from the source container surface
Dose equivalent rate
μSv/h
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