GB/T 38724-2020 English PDF (GBT38724-2020)

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GB/T 38724-2020: Furniture harmful substances -- Test method for radioactivity
GB/T 38724-2000
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 97.140
Y 80
GB/T 38724-2020
Furniture harmful substances - Test method for
radioactivity
ISSUED ON: APRIL 28, 2020
IMPLEMENTED ON: NOVEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Principles ... 6 
5 Instruments and devices ... 6 
6 Sample ... 7 
7 Test procedures ... 7 
8 Processing of test data ... 8 
9 Measurement uncertainty ... 9 
Bibliography ... 10 
Furniture harmful substances - Test method for
radioactivity
WARNING - Personnel using this Standard shall have practical experience
in formal laboratory work. This Standard does not point out all possible
safety issues. It is the user's responsibility to take appropriate safety and
health measures and to ensure compliance with the conditions
prescribed by the relevant national regulations.
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 γ 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 γ decay to emit
γ rays. Radioactive materials of different energy emit different energy carried
by γ rays. γ-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 γ spectrometer
Energy discriminative power ≤9%, background count rate ≤8 s-1, relative shift
of peak position within 8h ≤1%.
5.1.2 Semiconductor γ spectrometer
Energy discriminative power ≤2.5keV, relative shift of peak position within 8h
≤0.05%.
5.2 Standard source
5.2.1 γ 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.
to measure the specific activity of 226Ra, 232Th, 40K. The measurement time
depends on the radioactive intensity of the standard source or sample to be
measured. The measured time shall be 1h.
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,
Iγ - 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