Some standard content:
ICS_11.020
National Standard of the People's Republic of China
GB/T161411995
Analytical method for radionuclides by alpha spectrometry
Published on January 23, 1996
National Technical Supervision Bureau
Ministry of Health of the People's Republic of China
Implemented on July 1, 1996
National Standard of the People's Republic of China
Analytical method for radkonuclides by alpha spectrometry
Analytical method for radkonuclides by alpha spectrometry Spectrometry: Content and scope of application: H/T16141-1995 This standard specifies the analytical method for the composition and content of radioactive materials in radioactive conductors. This standard is applicable to the determination of low-level a radionuclides (energy greater than 10.0 MeV) in biological samples and environmental samples. 2 Principle of the method: After pretreatment and chemical separation, the electrodeposited sample to be tested is made into a soft metal detector composed of a gold-silicon surface barrier semiconductor detector with a certain degree of sensitivity. Retrograde measurement is performed in the measurement room. The particle interacts with the detector. The output of the front amplifier generates a pulse signal with energy greater than that of the incident particle. After being analyzed by the multi-pulse height analyzer, the energy of the particles is counted and classified according to energy (or ratio). The particle energy potential is then identified and the activity is determined. 3. Instrument equipment
3. Spectrometer system
3.2.1 Semiconductor detector
A gold-silicon surface barrier detector with a thickness of 60~100 μm and a sensitivity of 100 mm is selected. Conventional measurement 4 It is recommended to use a sensitive range of 300mm* to *Am%.487MeV a pillow energy resolution of 25~50keV, and the corresponding detection efficiency is not less than 20%.3.1.2 The total voltage is 0~30V continuously adjustable, the rated output current is 0-500A, and the stability is less than 0.2%. The ripple voltage is less than 15mV
3.1.3 Pre-monitoring amplifier
It is required to use a low-noise amplifier or a receiver with a sensitivity of 1×1ult/C and a noise The noise level is not more than 2.5 ± 0.U3 (keV/pF) 3.1.4 The amplifier should have an adjustable gain that matches the preamplifier. The gain change is better than 0.3, the integral nonlinearity is not more than 0.3%, and the noise level is not more than 10V.
3.1.5 The multi-channel pulse height analyzer
should be selected according to the requirements and the potential noise level, the range of the detector, the resolution of the detector, etc. The sensitivity of the multi-pulse analyzer is generally not less than 512 items
3.1.6 The test chamber
is made of stainless steel, with a single conductor detector and a sample channel installed. The distance between the sample holder and the depth detector is adjustable. The chamber is connected to the vacuum system. 3.2 Re-vacuum system
The vacuum system mainly includes vacuum pump, vacuum instrument and vacuum valve. The vacuum degree of this system shall meet the requirements of 4.1.3. Approved by the State Technical Supervision Bureau on December 15, 1995 and implemented on July 1, 1996
4 Harmonic instrument calibration
4.1 Selection of spectrum working state
CA/L 16141--1995
4.1.1 According to the spectral resolution experimental curve, the optimal response pressure is selected as the maximum value of the detector: each detector must be selected at normal pressure.
4.1.2 According to the activity of the sample and the composition of the sample, the distance from the sample to the detector is determined, which is generally within the range of 2 to 2000m. For low-activity radionuclides, 2 to 3m is appropriate. 4.1.3 The vacuum during measurement is generally controlled at 191P14-110*mmHg). The vacuum should not be too high to avoid nuclear reaction and detector contamination.
4.2 Scale
42.1 is used for energy measurement. The sample must be uniformly distributed and have no contamination on the surface. In fact, it should be able to cover the energy range of the sample. Commonly used monitoring sources include Pu (5.57MeV), \Am (E.48MeV), 1\Pu (5.305MeV) and natural ytterbium (4.0~68RMeV) and natural gas (4.01~8.7B5MeV) and other electrodeposition sources. 4.2.2 Select two or more single energy sources or one multi-energy scale α spectrometer. Usually the energy conversion coefficient is less than 10keV, and the energy nonlinearity shall not exceed 1%. 4.2.3 The energy conversion coefficient should be adjusted according to the energy curve. If the slope and intercept change significantly, the measurement will be affected and recalibration is required. 4.3 Efficiency calibration
4.3.1 The calibration source used for efficiency calibration must meet the requirements of good uniformity, with an uncertainty of less than 3.5%, and its geometric shape and size should be consistent with the sample to be measured. For the determination of low-activity radioactive nuclides, the activity of the calibration source is required to be 10-30 of the sample to be measured. 4.3.2 The relative geometric position of the calibration source and the detector must be strictly repeatable. 4.3.3 The detection efficiency of the spectrometer is calculated according to formula (1). The relative standard deviation of the detection efficiency should be less than ±3%R,
where, 5. — Detection efficiency of the spectrometer: R,.--Net counting rate of the calibration source, s-\
die. --The emission rate of the calibration source, 9-14.3.4 After the operating efficiency of the spectrometer is determined, the measurement geometry, the system configuration, etc. must be changed and the calibration must be renewed. 4.4 Stability of the harmonic structure
Under room temperature conditions: the spectrometer works continuously for 2 hours and the peak stability should be less than 0.2%: 5 Sample preparation
5.1 The sample plate required for a single analysis
7, the amount of small sample is calculated according to formula (2)
In the formula: Q
The missing sample base required for a single analysis,.)
Under the detection rule of the spectrometer, B
The concentration of the measured element in the sample is expected, Bg/R (F/; - Chemical yield of the measured nuclide.
h. Multiple sample plates are calculated according to formula (a):
In the formula: The upper limit value of the sample plate connected for a two-time analysis, (1.); 2
GE.T 16141—1995
3,—Specific activity of the measured nuclide, 1g/
α—Effective area of the sample to be measured + c
mThe maximum thickness of the sample element of the measured nuclide, 10R/cm, the meaning of Y is the same as that of formula 2).
5.2 Select a tracer with known activity as a tracer and add it to the sample to be analyzed in order to correct the chemical reaction rate of the model. The tracer should be a strict isotope of the sample, with accurate activity and long half-life. The amount of tracer depends on the activity and energy quality of the nuclide to be analyzed, so as to meet the statistical requirements of counting and not interfere with the analysis of the nuclide to be measured. Generally, a range of 10-50 is selected. 5.3 According to different samples and nuclides, different sample pretreatment methods and chemical separation are selected to separate and purify the nuclides to be analyzed.
5.4 Electrodeposit the nuclides to be tested on a rust plate (or platinum plate). The effective area of the sample to be tested should be smaller than the sensitive reagent of the detector. For chemical recovery, the thick source can be dissolved and re-prepared. After the electrodeposition source is prepared, it should be carried out in time. Energy spectrum measurement should be carried out to prevent the growth of the nuclides that interfere with the measurement. 5.5 Prepare the reagent blank sample in the same way. 6 Measure
6.1 Two calibrated instrument background and reagent blank samples of the spectrometer. For a specific chemical analysis sequence, measure 3-5 trial blank samples and calculate the average count rate (P) of the instrument without the background and the reagent blank sample in the energy range of each nuclide to be measured. 6.2 In the instrument configuration completely consistent with 6.1, measure the spectrum of the sample to be tested. The measurement time should be controlled according to the activity of the nuclide to be measured and the required accuracy.
7α Energy Spectrum Analysis Method
7.1 Determination of Energy Peak Area
Determine the energy peak and peak area of each energy sequence from the measured spectral increase. For nuclides emitting multiple energy rays, the peak area should include all energy peaks. And determine the peak area of the corresponding instrument background and reagent blank sample by the same method. 7.2 Activity of the Nuclide
a. When the added tracer is an auxiliary radionuclide (such as Th,,*Pu,,Am, etc., N./T.-N./T
A -- AN-NT
In Chinese: Ma:
Activity of the detected nuclide:
Activity of the added tracer.;
Integral count of the energy zone where the tracer is located
Integral count of the instrument background in the energy zone such as the reagent blank supplement:
N-Integral count of the instrument background in the energy zone where the tracer is located
N-Integral count of the instrument background in the energy zone where the tracer is located:
N-Counting time of the sample.3
Background counting time 9.
h. When the tracer is not the lightest radiation <1*Th, A
In the formula, E, —. The detection efficiency of the instrument
—chemical recovery rate of the tracer.
AN,NTT is the same as the formula (4).
7.3 Calculation of chemical recovery of tracer
NIT: -N/T.
（4）
Wu Zhong: F-
Chemical recovery of tracer:
- Net tracer
A,——Activity of added tracer,
F: Measurement efficiency only:
Counting time, 3.
7.4 Calculation of the concentration of the initial nuclide
: +
GE/T 16141:1995
Concentration of the nuclide being measured, g(BL)+
Amount of the sample being measured g.)
A:---Activity of the nuclide being measured or disturbed,
7.5 Interference
7.5.1 When the resolution is greater than 25keV, there may be overlaps, which should be corrected. 6
7-5.2 When analyzing multiple isotope samples of a single element at the same time, the energy overlap between the isotopes may cause mutual interference, which can be compensated by taking the branching ratio of the peak analysis rate. 8.1 The sample analysis report should include the accuracy of the nuclide rate and the corresponding counting standard deviation, and indicate the confidence level used. For the detection limit of the product, it should be expressed as "less than LD". Other errors such as accuracy error and chemical yield error should also be noted in the report. 8.2 The counting standard deviation S of the sample is calculated using the formula (8): S-+
Integral count of the new nuclide present in the energy: N
Integral count of the corresponding instrument background and reagent space from the sample: T
Sample counting time, 51
-reagent space occupies sample counting time + 9,
AT equipment
GB/T 16141—1995
Electrodeposition source of the sample to be tested
Test materials)
A1.1 DC power supply: voltage is 1~18, current is ~4, 1.2 New deposition device (A1)
Glass electrolytic
Stainless steel transformer
Vacuum diagram
Reason diagram
Electrodeposition film
Uncontrolled bottom
Figure A1Electrodeposition device rate
41.3 The deposition electrode is a stainless steel disk (or pin disk) with a diameter of 20mm and a thickness of c.5mm. The disk surface must be polished and cleaned. The diameter of the trap is 1 mm wire, one end of the wire is made into a ring with a diameter of mm. A2 Electrodeposition
A2.1 Filter and evaporate the purified sample to near dryness, A2.2 Dissolve the sample with 5 mL of electrolyte, heat, A2.3 Transfer the sample to the electrodeposition beaker, then wash the beaker with 5-10 mL of electrolyte, and transfer the washing liquid to the electrodeposition chamber:
GH/E 16141-1995
A2.4 Add 3-4% phenol blue indicator, then use 1.8 nal of trioxide (or periodic) to adjust the sample solution to FH test, until the sample solution turns red. A2.5 Release the current control. The distance between the anode and the electrode is 1 cmA?.6 Connect the electrodes to the power supply. Turn on the power supply, adjust the self-flow to 1.2A, electroplating 1, A2.71b later: 1mL method Ammonium hydride pad electrodeposition, hand maintenance continued to say the accumulation! mir. A2.8 Take out the anode and turn off the power supply. Run away and then use 0,1=l ammonium hydride cable to precipitate 6 times. A2.9 Dismantle the electrodeposition device, take out the reactance source, flush with wine, absorb the strong wine, and dry it. The detection limit of energy spectrum analysis
(test piece) bzxz.net
1 The detection limit of energy spectrum analysis can be approximately calculated by formula (1), LLD(K ,-K,)S
and the risk rate of the ring selection error judgment () corresponding to the standard stop state change percentile F: where K-
and the corresponding value of the traceability in the simple confidence (1): S-sample net efficacy compensation drug standard deviation, the result is 9 on the same level, purchase, ==.
B3 If the total column product dare to be close to the bottom of the car, it can be further simplified, LLD? 2KS=2.83K
or: T: the measurement time of this spectrum, R3
center, the detection integral count corresponding to a certain nuclide in this spectrum, 5, a standard deviation of the bed count rate
For different a and K values, as listed in Table B1, Table B1
is called the lower limit of the detection part, expressed in degrees. Then there is
in the formula.. The standard deviation of the sample release time, F,. The detection efficiency of the spectrometer;
Y--the chemical yield of the measured nuclide
Q--the sample plate gL,
center, 82
Nd-_44
Sun-147
Gel-14S
Gc-1:0
Ly-154
i-210m
Tsi -211
Bi-212
Pu-206
Pn-2n8
Pa-209
Po-210
Po-212
Por -214
Fo-2t5
Fo-216
Po-218
At-211
At-217
Rn-219
Rn- 222
IFr-221
Ra-224
Re-226
Ac-225
Th-227
Th-228
GB/I 16141--1995
The atomic sequence of the radiation
(Anti-parts)
Energy required, Mev
a4.953(57.6%).4.91636.0).4.568(5.0%)min 6.622(84.2%),6.278(15.8%)min
6.050(69.9%),6.090(27.1%).5.764.1.72%)5.61 (1.12%)
6.8:7(8125.51(11.5%).6.427.5%)6.289
E.310682%5. 116(1.2),.242(1.6%)5.714(55),5.605(24%,.745(9,5.37(9)5.43262.)||tt ||5.684(34.8%).5.448(5.2%)
4.791(9:.52,4.5815.56)
5.R2.( 2%,5.785<29%).5.724(9.5%).3.6304.0)5.716(2.6%).5.675(1.0/)
6. (36 (24. 5%), E, 97623. 4%).5. 755 (20.3%), 5. 77 (9.2), 5.711 (4.%) 5.659 (3.5%) 5.424 (71%) 5.341 (25%)
4.942 (58%), 4.899 (10.7%). 4.11 (11.4%) 5.054 (6. 7%), 1. 967 (6)
a687 (7656). 4.620 (24%)
specific activity Bq / g
2. .7 F13
G. : 1 E11
T6-232
Pz-231
1j-235
Na-237
1a-236
Pu-238
Pu 24C
Pu-2-2
Am-241
Am-243
Crp-240
Cm-243
Crr-244
Crr:-No.24
Cm-248
Bk 247
Cf-248
Cf-249
Cf-252
CI-252
Es-252||tt| |Es-254
Es-233
Fm-253
Fm-257
Note: The amount in brackets is the branch ratio
GB/T 16141 -1995
Main α group, Me
4.01(%),3.95(24%)
5.005<25%),4.4322.8%).5.022 20%),5.051(11.043.4-720(8.45%)
5.9,5.82(3%)
5.32(5S/).5.27(33%)| |tt||4.R21(83.4),1.78(14.6%)
4.773(72%),4.722(2R%)
4.39657),4.36 (18%),4.216(5.7%),1.57(4.56)4.49(75%),4.44(24%)
1.2075%).4.15(25 way)||t t||4.755(42%).4.7(28%)+4.636(6%3.4.5B1(3.3%)5.769(69/6)+5.722(31%)
5. 499(72%).5.456(28%)
5.157(73.3%),5.145(15%).5.107(11.5%)5.169(766),5. 123(24%)
4.903(76%),4.863(24%
5.487(85%).5.444(13)
5.276(7. 9%),5.234(1.6)
6.254(72%),6.250(28)
6.15(73.525.0726.5)
5.7 86(73%).5.742(11.556),5.9$4(6%),6.0615)5.8076.7%).5.765(23.3%)
5.362( ,5.461(<3%),5.3067)
.396(81%),5.342119%
5.08(82%),5.34(18%)||tt| |F.52(58%).5.68(3736),5.31(26).27(82%),6.22(1)
5.812(84%),5.755(4.4%)
6.031(83),5.9R7417)
5.666(55%),5.845(45)
.11S(84.3%).6.075 (15.5%)
6.64(82%),6.5$(13%)
6.64(S0%),6.597(6.6)
6.437(93), 6.367(2.3%)
6.96(.5%),5.91(18.2%)
6.526(94%),5.703(3.2%),6.450(2 .2%) The ratio of the discrete price of two or more equal determination methods in the variable, the ratio of addition, Be/g
Additional instructions
GB/T16141-1995
Technical new standard The Ministry of Health of the People's Republic of China proposed this standard. The Industrial Five Life Laboratory of the Ministry of Health was responsible for drafting. The main drafters of this standard were Kuai Qingmei and Xin Meirong. The Ministry of Health entrusted the technical department of this standard to the Industrial Hygiene Inspection Institute of the Ministry of Health for interpretation.
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