GB/T 38724-2020Furniture harmful substances—Test method for radioactivity (English PDF)
家具中有害物质 放射性的测定
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
April 28, 2020
Implementation date
November 1, 2020
Scope
GB/T 38724-2020 is the English-translated version of 家具中有害物质 放射性的测定.
GB/T 38724-2020 specifies the terms and definitions, principles, instruments and devices, samples, test procedures, test data processing and measurement uncertainty of the test method for radioactive materials in furniture.
Clause 1 states that the standard is applicable to furniture products and components made of inorganic non-metallic materials, and a warning at the head of the text says that users are to have practical experience in formal laboratory work and remain responsible for appropriate safety and health measures.
The table of contents gives nine clauses: Scope, Normative references, Terms and definitions, Principles, Instruments and devices, Sample, Test procedures, Processing of test data and Measurement uncertainty, followed by a bibliography.
Clause 4 explains that the radioactivity of furniture is determined mainly by the inorganic non-metallic materials it contains, and that a prepared and pretreated sample placed on the detector emits gamma rays by decay, which enter the scintillator and release electrons at the photocathode of a photomultiplier tube to form the output signal.
Clause 5 requires a low background multi-channel gamma spectrometer, either a sodium iodide instrument with an energy discriminative power of 9 percent or less, a background count rate of 8 per second or less and a relative peak position shift within 8 hours of 1 percent or less, or a semiconductor instrument with an energy discriminative power of 2.5 keV or less and a peak shift of 0.05 percent or less, together with standard sources of 226Ra, 232Th and 40K meeting JJG 417, an electronic balance of class II accurate to 0.1 g and an oven held at 105 plus or minus 5 degrees C. Clause 8 calculates an internal exposure index from the specific activity of 226Ra against a limit of 200 Bq/kg, and an external exposure index from the specific activities of 226Ra, 232Th and 40K against limits of 370, 260 and 4200 Bq/kg taken separately when only external exposure is considered.
Clause 2 cites JJG 417 alone, and clause 3 defines inorganic nonmetallic materials, with ceramics, cement, refractory materials and enamel given as examples, and then opens an entry 3.2 for the internal exposure index IRa whose definition text the preview cuts off. It was issued on April 28, 2020 and has applied since November 01, 2020.
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Document preview — GB/T 38724-2020
National Standard of the People's Republic of China
- ICS
- 97.140
- Classification
- Y 80
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword3
- 1 Scope4
- 2 Normative references4
- 3 Terms and definitions4
- 4 Principles6
- 5 Instruments and devices6
- 6 Sample7
- 7 Test procedures7
- 8 Processing of test data8
- 9 Measurement uncertainty9
- Bibliography10
1 Scope
This Standard specifies the terms and definitions, principles, instruments and devices, samples, test procedures, test data processing and measurement uncertainty of radioactive material test methods in furniture.
This Standard is applicable to furniture products and components made of inorganic non-metallic materials.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
JJG 417, Verification Regulation of gamma Ray Spectrometers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Inorganic nonmetallic materials
A class of materials mainly composed of oxides, carbides, nitrides, borides, chalcogenides, silicates, titanates, aluminates, phosphates and other oxygenates of certain elements.
Example: Traditional inorganic materials such as ceramics, cement, refractory materials, enamel and new (special) inorganic materials, etc.
3.2 Internal exposure index; IRa
4 Principles
The radioactivity of furniture is mainly determined by the inorganic non-metallic materials it contains. Place radioactive furniture materials on the detector after preparation and pretreatment. Radioactive material undergoes gamma decay to emit gamma rays. Radioactive materials of different energy emit different energy carried by gamma rays. gamma-ray enters the scintillator, and finally emits electrons on the photocathode of the photomultiplier tube, and the signal output is formed after multiplication.
5 Instruments and devices
5.1 Low background multi-channel gamma spectrometer
5.1.1 Sodium iodide gamma spectrometer
Energy discriminative power <=9%, background count rate <=8 s-1, relative shift of peak position within 8h <=1%.
5.1.2 Semiconductor gamma spectrometer
Energy discriminative power <=2.5keV, relative shift of peak position within 8h <=0.05%.
5.2 Standard source
5.2.1 gamma spectrometer used to calibrate sodium iodide
A set of standard sources including 226Ra, 232Th, 40K and the hybrid source shall be configured, where three standard sources, 226Ra, 232Th and 40K, are used to calibrate the spectrometer, the hybrid source is used for analysis and inspection, and the standard source shall meet the requirements specified in JJG 417.
5.2.2 gamma spectrometer used to calibrate semiconductor
It shall be equipped with a point standard source suitable for the nuclide to be determined. The point standard source shall meet the requirements specified in JJG 417.
5.3 Electronic balance
Accuracy is 0.1g, level II.
5.4 Oven
Temperature is (105±5)°C.
8 Processing of test data
8.1 Internal exposure index
Internal exposure index is calculated according to formula (1): Where, IRa - Internal exposure index;
CRa - Specific activity of natural radionuclide 226Ra in furniture materials, in becquerel per kilogram (Bq/kg);
200 - Specific activity limit specified in this Standard of radionuclide, 226Ra, in the furniture materials specified in this Standard, in becquerel per kilogram (Bq/kg).
8.2 External exposure index
External exposure index is calculated according to formula (2): Where, Igamma - External exposure index;
CRa, CTh, CK - Specific activity of natural radionuclides 226Ra, 232Th, 40K in furniture materials, in becquerel per kilogram (Bq/kg);
370, 260, 4200 - Specific activity limits specified in this Standard of radionuclides, 226Ra, 232Th, 40K in the furniture materials specified in this Standard when they exist separately when only external exposure is considered, in becquerel per kilogram (Bq/kg). […]
8.3 Result representation
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
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