Some standard content:
National Standard of the People's Republic of China
Standard methods for radon measurement in environmental air
Standard methods for radon measurement in environmental air1 Subject content and scope of application
GB/T 14582-93
This standard specifies four methods for measuring oxygen and its progeny in environmental air, namely, track etching method, activated carbon box method, double filter membrane method and balloon method.
This standard is applicable to the determination of hydrogen-222 and its radon potential concentration in indoor and outdoor air. 2 Terminology
2.1 Hydrogen progeny alpha potential
The sum of the energy of the particles released during the complete decay of chlorine progeny into lead-210. 2.2 Hydrogen progeny alpha potential
The alpha potential value of oxygen in unit volume of air. 2.3 Filtration efficiency of filter membrane
When using filter membrane to sample airborne particles in the air, the percentage of airborne particles collected by the filter membrane in the sampling volume. 2.4 Counting efficiency
Under certain measurement conditions, the ratio of the number of particles measured to the total number of particles of the same type emitted by the radioactive source in the same time interval. 2.5 Waiting time
The time interval from the end of sampling to the midpoint of the measurement time. 2.6 Detection limit
The minimum concentration of radioactive substances detected at 95% confidence level. 3 Track etching method
3.1 Method summary
This method is a passive sampling method that can measure the cumulative concentration of hydrogen during the sampling period. After exposure for 20 days, its detection limit can reach 2.1×10\B. h/m°. The detector is a carbon fiber sheet or CR-39, which is placed in a sampling box of a certain shape to form a sampler, as shown in Figure 1.
When the particles emitted by hydrogen and its daughters hit the detector, it will produce submicroscopic damage tracks. The detector is chemically or electrochemically etched under certain conditions to expand the damage tracks, which can be counted with a microscope or a dynamic counting device. The number of tracks per unit area is proportional to the product of the ammonia concentration and the exposure time. The track density can be converted into ammonia concentration using the scale factor. Guohao Environmental Protection Bureau 1 993-0 8- 1 4 approved 1994-04-01 implementation
3.2 Equipment or materials
GB/T 14582-93
Figure 1 Structure diagram of track etching method sampler
1-sampling box, 2-pressure cover: 3-filter membrane; 4 detector detector, polycarbonate membrane, CR-39 (referred to as film): sampling box, made of plastic. Diameter 60tum high 30mm etching groove, material ring,
audio high voltage vibration medicine power supply, frequency 0~10 kHz, voltage 0~~1. 5 kV, thermostat, 0~100℃, error ±0.5℃; slicer:
thickness gauge, can measure micron thickness,
clock:
syringe, 10 L.30 ml Two types;
Beaker, 50mL;
Chemical reagents, analytical pure potassium hydroxide (containing at least 80%), anhydrous ethanol (CH,OH) flat head,
Filter membrane.
3.3 Polycarbonate sheet operation procedure
3.3.1 Sample preparation
3.3.1.1 Slicing. Use a slicing machine to cut the polycarbonate film into slices of a certain shape, generally round or square. 3. 3. 1. 2
Thickness measurement. Use a thickness gauge to measure the thickness of each slice, and the slices that deviate from the nominal value by 10% should be discarded. 3.3.1.3 Sample loading. Use glue to fix the three slices at the bottom of the sampling box, and cover the box mouth with a filter membrane. 3.3.1.4 Sealing. Seal the sampler case to isolate it from the outside air. 3.3.2 Placement
3.3.2.1 Remove the sealed package at the measurement site. 3.3.2.2 Place the sampler at the measurement site. The sampling conditions must comply with the requirements of Appendix A (Supplement) A2. 3.3.2.3 Indoor measurement. The sampler can be hung or placed on other objects. No other objects should be within 20m above its opening.
3.3.3 Retrieval of the sampler
When sampling is terminated, remove the sampler, seal it again, and return it to the laboratory. The placement time shall not be less than 30 days. 3.3.4 Records
Contents to be recorded during sampling are shown in Appendix A (Supplement) A3. 3.3.5 Etching
3.3.5.1 Preparation of etching solution
3.3.5.1.1 Preparation of potassium oxychloride solution: Dissolve 80 g of analytical pure potassium hydroxide (content not less than 80%) in 250 g of distilled water to make a solution with a concentration of 16 mmol (m2/m3).
GB/T 14582—93
3.3.5.1.2 Chemical etching solution: the volume ratio of potassium oxychloride solution (3.3.5.1.1) to CH,0H is 1:2. 3.3.5.1.3 Electrochemical etching solution: the volume ratio of potassium oxide solution (3.3.5.1.1) to CH,0H is 1*0.36. 3.3.5.2 Chemical etching
3.3. 5.2. 1 Take 10 m[. of chemical etching solution and add it to a beaker. Place the detector in the beaker. The beaker should be numbered. 3.3.5.2.2 Place the beaker in a thermostat and place it at 60°C for 30 min. 3.3.5.2.3 After chemical etching, wash the film with water and dry it. 3.3.5.3 Electrochemical Etching
3. 3.5.3.1 Measure the thickness of the wafer after chemical etching and group the wafers with similar thickness. 3.3-5-3.2 Fix the wafer in the etching tank, fill each tank with electrochemical etching solution, and place the electrodes. 3.3.5.3.3 Place the etching tank in a thermostat, apply voltage (20 kV/cm, if the wafer thickness is 200 μm, then 400 V), frequency 1 kHz, and place at 60℃ for 2 h.
3. 3. 5. 3.4 After 2 h, remove the wafer, wash it with clean water, and dry it. 3. 3.6 Counting and Calculation
3.3.6.1 Counting. Use a microscope to measure the number of tracks per unit area on the processed wafer. 3. 3.6.2 Calculation. Calculate the concentration using formula (1): Gika
Where: CRn
Ammonia concentration, Bq/m:
Net track density, 7\/cm
T-Exposure time, hr
Fk-Scale factor, T./cm°/Bo · h/mlTrack number.
3.4CR-39 sheet operation procedure
3.4.1 Sample preparation
3.4.1.1 Slicing. Use a slicer to cut the CR-39 sheet into round or square slices of a certain size. 3.4.1.2 Sample loading. Same as 3.3.1.3 Tea.
3.4. 1.3 Sealing. Same as 3. 3. 1. 4. 3.4.2 Laying out
Same as 3. 3. 2.
3.4.3 Recycling of the sampler
Same as 3.3.3.
3.4.4 Record
Same as 3.3.4.
3.4.5 Etching
3.4.5.1 Preparation of etching solution
Use chemically pure potassium hydroxide to prepare an etching solution with c(KOH)=6.5mol/I. 3.4.5.2 Chemical etching
3.4.5.2.1 Draw 20mL of etching solution into a beaker, take out the slice and place it in the beaker, and the beaker should be numbered. 3.4.5.2.2 Put the beaker into a thermostat and place it at 70 for 10h. 3.4.5.2.3 After chemical etching, wash the slice with water and dry it. 3.4.6 Counting and calculation
Same as 3.3.6.
3.5 Quality Assurance
3.5.1 Calibration
GB/T14582—93
3.5.1.1 Place the prepared sampler in the hydrogen chamber, expose for - chain time, treat the detector with the specified etching procedure, and calculate the calibration coefficient Fkp by formula (2). The meaning of the symbols in the formula is shown in 3.3.6.2.
3.5.1.2 The following conditions should be met during calibration: The concentration of hydrogen and its daughters in the ammonia chamber does not change with time. The hydrogen level in the nitrogen atmosphere can be 10 to 30 times that of the investigation site. At least two levels of calibration should be done. h.
At least 4 samplers should be placed at each concentration level. c.
The exposure time should be long enough to ensure that the concentration inside and outside the sampler is balanced. d.
Each batch of detectors must be calibrated.
3.5.2. Parallel sampling
Two samplers should be placed in parallel in the selected place, and the number of samples should not be less than 10% of the total number of hoods placed. The parallel samplers should be treated in the same way and analyzed.
The coefficient of variation obtained from the parallel samples should be less than 20%. If it is greater than 20%, the error in the processing procedure should be found. 3.5.3. Blank samples
When preparing samples, take out a part of the detectors as dense white samples, and the number should not be less than 5% of the total number used. The blank detectors are treated in the same way as the on-site detectors except that they are not exposed to the sampling point. The result of the blank sample is the background value of the detector. 4. Activated carbon box method
4.1 Summary of the method
The activated carbon box method is also a passive sample, which can measure the average hydrogen concentration during the sampling period. After 3 days of exposure, the detection limit can reach 6 Ba/ma.
The sampling box is made of plastic or metal, with a diameter of 6 to 10 cm and a height of 3 to 5 cm. It contains 25 to 100 g of activated carbon. The knocked-open side of the box is sealed with a filter membrane, and the fixed activated carbon is allowed to enter the sampler. As shown in Figure 2: Figure 2 Activated carbon box structure
1-rolling cover: 2-filter membrane, 3-activated carbon: 4-charcoal box air diffuses into the carbon bed, and the hydrogen in it is adsorbed by the activated carbon and decays at the same time, and the new body is deposited in the activated carbon. The spectrometer is used to measure the intensity of the hydrogen body characteristic 7-ray peak (or bee colony) of the activated carbon box. The hydrogen concentration can be calculated based on the characteristic peak area. 4.2 Equipment or materials
Activated carbon, coconut shell charcoal 8-16 mesh +
Sampling box, size 4.1;
d, Tianhu, sensitivity 0.1mg, range 200glGB/T14582-93
e spectrometer, NaI (Tl) or semiconductor probe with multi-channel pulse analyzer: f. Filter membrane.
4.3 Operation Procedure
4. 3. 1 Sample Preparation
4. 3- 1. 1
4. 3. 1. 2
4. 3. 1. 3
Put the selected activated carbon into an oven and bake it at 120℃ for 5~～6h, then store it in a ground-mouth bottle for later use. Sample Loading. Weigh a certain amount of baked activated carbon and put it into a sampling box, and cover it with a filter membrane. Then weigh the total weight of the sample box.
4.3.1.4 Seal the activated carbon box to isolate it from the outside air. 4.3.2 Placement
4.3.2.1 Remove the sealed package at the site to be tested and place it for 3~7 days. Place the activated carbon box at the sampling point, and its sampling conditions must meet the requirements of Appendix A (Supplement) A2. 4.3.2.2
4.3.2.3 The activated carbon box is placed on a table or shelf 50 cm above the ground, with the open side facing upwards. No other objects should be placed within 20 cm above it.
4.3.3 Sample recovery
When sampling is terminated, seal the activated carbon box again and return it to the laboratory immediately. 4.3.4 Records
The contents to be recorded during the sampling period are shown in Appendix A (Supplementary) A3.4.3.5 Measurement and calculation
4.3.5.1 Measure
a, measure 3 hours after sampling is stopped.
bh, weigh again to calculate the water absorption. c Count the activated carbon box on the spectrometer and measure the area of the hydrogen daughter characteristic ray peak (or peak group). The measurement geometric conditions should be consistent with the scale.
4.3.5.2 Calculation
Calculate the hydrogen concentration using formula (3):
Wherein: C
hydrogen concentration, Bg/m*
response coefficient of the sample for 1 hour, Bq/m*/count/min, n.-net count rate corresponding to the characteristic peak (peak group), count/min sampling time, h,
6-case accumulation index, 0.49;
ARn-hydrogen decay constant, 7. 55 × 10- /h; ta
the time interval between the midpoint of the sampling time and the start of the measurement, h. 4.4 Quality Assurance Measures
The quality assurance measures for nitrogen determination using the activated carbon box method are as follows 3.5. The response coefficient 2 should be calibrated at different humidity levels (at least three humidity levels: 30%, 50%, and 80%).
5 Double filter membrane method
5.1 Method summary
GB/T 14582—93
This method is an active sampling method, which can measure the hydrogen concentration at the moment of sampling, and the detection limit is 3.3B/m. The sampling device is shown in Figure 3. After the vacuum pump is turned on, the hydrogen-containing air enters the decay chamber through the filter membrane. The pure hydrogen of the daughter body that is filtered out will generate new daughter bodies in the process of passing through the decay chamber, and part of the new daughter bodies will be collected by the outlet filter membrane. The ammonia concentration can be converted by measuring the α radioactivity on the outlet filter membrane.
Figure 8 Schematic diagram of the sampling system of the double filter membrane method
1-inlet membrane; 2-decaying tube: 3-outlet membrane; 4-flow meter: 5-vacuum pump 5-2 Equipment or materials
decaying tube, 14,8L
flow meter, rotor flow meter with a range of 80 L/min; vacuum pump +
α measuring instrument, which should have similar counting efficiency for α particles of RaA and RaC'; particle filter;
sampling clamp, filter membrane that can hold 0;
stopwatch,
fiber filter membrane:
a reference source, \Am or *Pu
tweezers.
5.3 Inspection before measurement
Inspection of sampling system
Whether the vacuum pump operates normally, whether the specified sampling flow rate can be reached, and whether the flow meter works normally.
Check whether the sampling system has any leaks.
5.3.2 Check the counting equipment
Check whether the counting stopwatch works normally.
b. Check whether the counting efficiency and background of the α measuring instrument have changed. c. Check the stability of the measuring instrument and measure the α source ten times per minute. The results shall be tested by X”. If the working status is abnormal, the reasons shall be found out and handled.
5.4 Point arrangement
5. 4. 1 Indoor measurement
Indoor sampling measurement shall meet the following requirements: a. Point arrangement principles and sampling conditions shall meet the requirements of Appendix A (Supplement) A2. b. The air inlet shall be about 1.5m above the ground, and the height difference with the air outlet shall be greater than 50rm, and in different directions. 5.4.2 Outdoor measurement
Outdoor sampling measurement shall meet the following requirements: a-
The sampling point shall be clearly marked.
It shall be far away from the road and smokestack.
GB/T 14582—93
The terrain shall be open, and there shall be no trees or buildings within 10 meters around. If 24h continuous measurement is not possible, sampling measurement shall be carried out from 8 am to 12 pm, and for 2 consecutive hours. d. d.
Stop sampling within 24 hours after rain or within 12 hours after strong wind on rainy days. 5.5 Records
The contents to be recorded during sampling are shown in Appendix A (Supplement) A3. 5.6 Operating procedures
Install the filter membrane and connect the sampling equipment according to Figure 3. a.
Sampling at a flow rate of g (L/min) min.
Measure the α radioactivity on the outlet membrane within a time interval of 1~ after the end of sampling. d.
Calculate the ammonia concentration using formula (4):
CR -K,· N.
Where: Cr. Hydrogen concentration. Bq/m*bzxZ.net
K, total scale factor, /m/count;
N,T;~T2 Net count of interval, count: decay cylinder volume, L;
F——counting efficiency, %I
7——filter membrane filtration efficiency, %;
β——membrane self-absorption factor for particles, %, Z.: constant related to t, T, T
The fraction of newly born daughters reaching the outlet filter membrane, %. 5.7 Coefficient calibration
5. 7.1 Method for determining E
a Under the same geometric conditions as the sample measurement, measure the net counting rate of the α standard source; b. Divide the counting rate by the activity of the source to obtain the counting efficiency E; c. Energy correction should be performed for different detectors. 5.7.2 Method for determining
According to the specified sampling conditions, collect the nitrogen daughters on the filter membrane. Wait for 30 After that, under the same conditions, the α counts on the front and back sides of the filter membrane are measured quickly (1 min each time) and covered with blank filter membranes of similar mass and thickness. The α counts are recorded as C1, Cb, and Cb.
Calculate according to formula (5):
Where: C, - front α count rate, counts/min; c - back α count rate, counts/min;
C, - α count rate after the front side is covered with a blank filter membrane of the same mass, counts/min. c. The β value should be measured for each batch of filter membranes. At least 3 samples should be measured each time and the average value should be calculated. 5. 7. 3 The determination method is also
. Select 2 filter membranes of similar mass and thickness and overlap them together. There should be 2.0mm distance quotient. Sampling at the specified flow rate for 5 min,
GA/T 14582--93
b. After sampling, install the two filter membranes on two identical sampling heads, measure alternately on the same instrument or measure in parallel on two instruments (the efficiency of the network station instrument should be corrected for the difference), and obtain two decay curves: the counts at the same time or the same time interval, and get n1n2, substitute into formula (6) to get the pregnancy value. c.
In the formula, n
the count of the first filter membrane:
the count of the second filter membrane.
5.7.4 Determination of Z
Use formula (7> to calculate the time of passing through the decay tube: a.
7. 0. 06 / S
Wherein: T-
Time of oxygen passing through the decay tube;
-length of decay tube, cm
S-cross-sectional area of decay tube, cm\
g-sample flow rate, L/min.
b. When T<10 s, refer to Table 1.
Z value table (T10s)
3.411 6.314
When T10 s, refer to Table 2 for the value.
2-3123. 803
5.425 11. 0682.656
7.07015. 381
5.7.5Fi is determined by the method
a. Calculate according to formula (8):
a dimensionless constant;
wherein:
GB/T14582—93
Table 2z value table (10s)
T,-T,.min
1)——diffusion coefficient of newly generated body, 0.085 cm*/s;1—decay length, cm;
sampling flow rate, cm2/s.
Find the value from Table 3 according to the output value
14-401
Table 3F, Value Table
5.8 Quality Assurance Measures
5.8.1 Calibration
GB/T 14582-.-93
Continued Table 8
Calibrate the measuring device once a year using a standard hydrogen chamber to obtain the total calibration coefficient. 5.8.2 Parallel Measurement
Use another method to conduct parallel sampling and measurement with this method. Use the paired data t test method to test the difference between the results of the two methods. If t exceeds the critical value, the reason should be found out. The number of parallel sampling shall not be less than 10% of the number of samples. 5.8.3 Operation precautions
The inlet filter membrane should have at least 3 layers to filter out all the chlorine daughters. The sampling head size should be consistent to ensure that the distance between the filter membrane surface and the detector is about 2m. Strictly control the operation time and do not make any mistakes, otherwise the sample will be invalid. If the relative humidity is lower than 20%, humidity calibration should be performed! The sampling device should be consistent with the flow meter scale conditions. Balloon method
6.1 Method summary
This method is an active sampling method that can measure the concentration of hydrogen and its daughters in the air in the sampling room. The detection limit is 2.2 Ba/m for hydrogen and 5.7X10-7 J/m* for daughters.
The balloon method sampling system is shown in Figure 4. Its working principle is the same as the double filter method, except that the balloon replaces the decay element. The balloon method for measuring ammonia and the Markov method for measuring energy are combined. The operation takes 26 minutes to obtain the potential increase of hydrogen and its daughters. The time program is shown in Figure 5. 6.2 Instruments and Equipment The instruments or equipment required for the balloon method are: sampling head, capable of clamping a 50mm filter membrane, flow meter, impeller flow meter with a range of 80L/miz: vacuum pump, balloon, latex balls No. 20~50: a measuring instrument, the detector diameter is more than 5cm, and it has similar counting efficiency for a particles of ReA and RaC'; α reference source, 2Am or Pu source; filter membrane: stopwatch; tweezers.
6.3 Inspection before measurement
GB/T14582:93
Figure 4 Schematic diagram of the balloon sampling system
1-Sampling head: 2-Flowmeter; 3-Gas system 14-Throttle valve 5-Ring; 6-Balloon sample
Substrate sample
Figure Time program for balloon measurement
Sampling counter
Before each measurement, the sampling equipment and counting instruments must be strictly inspected. The inspection content is shown in 5.3. 6.4 Point arrangement
6.4.1 Indoor measurement
For indoor sampling measurement, the point arrangement principle and sampling conditions must meet the requirements of Appendix A (Supplement) A2, h. The air inlet is about 1.5m above the ground.
6.4.2 Outdoor measurement
For outdoor sampling measurement, the point arrangement principle and sampling conditions are the same as those in Article 5.4. 6.5 Records
The contents to be recorded during sampling are shown in Appendix A (Supplementary) A3. Operation procedures
Install the person, remove the filter membrane, and connect the sampling equipment; h
Inflate the balloon at a flow rate of 40 L/min within Q~~5 min, remove the inlet sample head and place it on the counter, and connect the balloon outlet to the vacuum pump: exhaust at a flow rate of 50 L/min within 10~14 min; measure the α radioactivity of the inlet filter membrane within 12~~15 min; measure the α radioactivity on the outlet filter membrane within 16~26 min: use formula (9) to calculate the α potential concentration:
Where Ce
-α potential concentration, J/m
GB/T 14582—93
p=Km(N—3R)
K.—Total coefficient of Markov method. J/m·Counts; Ne—Total counts of an inlet filter, let: R-background count rate, counts/min.
Use formula (10) to calculate ammonia concentration;
Crn=K,(Nr—10R)
Where: Cra
Oxygen leakage, Bg/m
Balloon scale constant, Bg/m. Counts;
Ne—Total α counts of the outlet filter, counts: R
Same as formula (9).
6.7 Determination of K
Use Kusnitz to calibrate the total coefficient Km of the Markov method6.7. 1 Calibration method
Sampling at a specified flow rate for 5min!
h, measuring the α count (Nr)c of the filter sample within 7~10min after the sampling, and performing the first α count of this sample at any time interval within 40~90min after the sampling (such as measuring for 10min), and the net α count is Ne.
Use formula (11) to calculate Km
-Kusnitz coefficient/m·count.
Where: Kk-
e. Perform at least 3 measurements and find the average value of K. 6. 7. 2 Determination of Kk
6. 7. 2. 1. Kk is determined by formula (12):
-sampling flow rate, L/min;
E——counting efficiency,;
-membrane filtration efficiency, %;
Kk* Nk
4.16×10-
[230-2T(40≤T≤70)
195 -1. 5T(70T$90)
(13）5Fi is determined by
a. Calculate according to formula (8):
a dimensionless constant;
wherein:
GB/T14582-93
Table 2z value table (10s)
T,-T,.min
1)——diffusion coefficient of newly generated body, 0.085 cm*/s; 1—decay length, cm;
sampling flow rate, cm2/s.
Find the value from Table 3 according to the output value
14-401
Table 3F, Value Table
5.8 Quality Assurance Measures
5.8.1 Calibration
GB/T 14582-.-93
Continued Table 8
Calibrate the measuring device once a year using a standard hydrogen chamber to obtain the total calibration coefficient. 5.8.2 Parallel Measurement
Use another method to conduct parallel sampling and measurement with this method. Use the paired data t test method to test the difference between the results of the two methods. If t exceeds the critical value, the reason should be found out. The number of parallel sampling shall not be less than 10% of the number of samples. 5.8.3 Operation precautions
There should be at least 3 layers of inlet filter membrane to filter out all chlorine daughters. The sampling head size should be consistent to ensure that the distance between the filter membrane surface and the detector is about 2m. Strictly control the operation time and do not make any mistakes, otherwise the sample will be invalid. If the relative humidity is lower than 20%, humidity correction should be performed! The sampling device should be consistent with the flow meter scale conditions. Balloon method
6.1 Method summary
This method is an active sampling method that can measure the concentration of hydrogen and its daughters in the air in the sampling room. The detection limit is 2.2 Ba/m for hydrogen and 5.7X10-7 J/m* for daughters.
The balloon method sampling system is shown in Figure 4. Its working principle is the same as the double filter method, except that the balloon replaces the decay element. The balloon method for measuring ammonia and the Markov method for measuring energy are combined. The operation takes 26 minutes to obtain the potential increase of hydrogen and its daughters. The time program is shown in Figure 5. 6.2 Instruments and Equipment The instruments or equipment required for the balloon method are: sampling head, capable of clamping a 50mm filter membrane, flow meter, impeller flow meter with a range of 80L/miz: vacuum pump, balloon, latex balls No. 20~50: a measuring instrument, the detector diameter is more than 5cm, and it has similar counting efficiency for a particles of ReA and RaC'; α reference source, 2Am or Pu source; filter membrane: stopwatch; tweezers.
6.3 Inspection before measurement
GB/T14582:93
Figure 4 Schematic diagram of the balloon sampling system
1-Sampling head: 2-Flowmeter; 3-Gas system 14-Throttle valve 5-Ring; 6-Balloon sample
Substrate sample
Figure Time program for balloon measurement
Sampling counter
Before each measurement, the sampling equipment and counting instruments must be strictly inspected. The inspection content is shown in 5.3. 6.4 Point arrangement
6.4.1 Indoor measurement
For indoor sampling measurement, the point arrangement principle and sampling conditions must meet the requirements of Appendix A (Supplement) A2, h. The air inlet is about 1.5m above the ground.
6.4.2 Outdoor measurement
For outdoor sampling measurement, the point arrangement principle and sampling conditions are the same as those in Article 5.4. 6.5 Records
The contents to be recorded during sampling are shown in Appendix A (Supplementary) A3. Operation procedures
Install the person, remove the filter membrane, and connect the sampling equipment; h
Inflate the balloon at a flow rate of 40 L/min within Q~~5 min, remove the inlet sample head and place it on the counter, and connect the balloon outlet to the vacuum pump: exhaust at a flow rate of 50 L/min within 10~14 min; measure the α radioactivity of the inlet filter membrane within 12~~15 min; measure the α radioactivity on the outlet filter membrane within 16~26 min: use formula (9) to calculate the α potential concentration:
Where Ce
-α potential concentration, J/m
GB/T 14582—93
p=Km(N—3R)
K.—Total coefficient of Markov method. J/m·Counts; Ne—Total counts of an inlet filter, let: R-background count rate, counts/min.
Use formula (10) to calculate ammonia concentration;
Crn=K,(Nr—10R)
Where: Cra
Oxygen leakage, Bg/m
Balloon scale constant, Bg/m. Counts;
Ne—Total α counts of the outlet filter, counts: R
Same as formula (9).
6.7 Determination of K
Use Kusnitz to calibrate the total coefficient Km of the Markov method6.7. 1 Calibration method
Sampling at a specified flow rate for 5min!
h, measuring the α count (Nr)c of the filter membrane sample within 7~10min after the sampling, and performing the first α count of this sample at any time interval within 40~90min after the sampling (such as measuring for 10min), and the net α count is Ne.
Use formula (11) to calculate Km
-Kusnitz coefficient/m·count.
Where: Kk-
e. Perform at least 3 measurements and calculate K. Approximately the average value. 6. 7. 2 Determination of Kk
6. 7. 2. 1. Kk is determined by formula (12):
-sampling flow rate, L/min;
E——counting efficiency,;
-membrane filtration efficiency, %;
Kk* Nk
4.16×10-
[230-2T(40≤T≤70)
195 -1. 5T(70T$90)
(13）5Fi is determined by
a. Calculate according to formula (8):
a dimensionless constant;
wherein:
GB/T14582-93
Table 2z value table (10s)
T,-T,.min
1)——diffusion coefficient of newly generated body, 0.085 cm*/s; 1—decay length, cm;
sampling flow rate, cm2/s.
Find the value from Table 3 according to the output value
14-401
Table 3F, Value Table
5.8 Quality Assurance Measures
5.8.1 Calibration
GB/T 14582-.-93
Continued Table 8
Calibrate the measuring device once a year using a standard hydrogen chamber to obtain the total calibration coefficient. 5.8.2 Parallel Measurement
Use another method to conduct parallel sampling and measurement with this method. Use the paired data t test method to test the difference between the results of the two methods. If t exceeds the critical value, the reason should be found out. The number of parallel sampling shall not be less than 10% of the number of samples. 5.8.3 Operation precautions
The inlet filter membrane should have at least 3 layers to filter out all the chlorine daughters. The sampling head size should be consistent to ensure that the distance between the filter membrane surface and the detector is about 2m. Strictly control the operation time and do not make any mistakes, otherwise the sample will be invalid. If the relative humidity is lower than 20%, humidity calibration should be performed! The sampling device should be consistent with the flow meter scale conditions. Balloon method
6.1 Method summary
This method is an active sampling method that can measure the concentration of hydrogen and its daughters in the air in the sampling room. The detection limit is 2.2 Ba/m for hydrogen and 5.7X10-7 J/m* for daughters.
The balloon method sampling system is shown in Figure 4. Its working principle is the same as the double filter method, except that the balloon replaces the decay element. The balloon method for measuring ammonia and the Markov method for measuring energy are combined. The operation takes 26 minutes to obtain the potential increase of hydrogen and its daughters. The time program is shown in Figure 5. 6.2 Instruments and Equipment The instruments or equipment required for the balloon method are: sampling head, capable of clamping a 50mm filter membrane, flow meter, impeller flow meter with a range of 80L/miz: vacuum pump, balloon, latex balls No. 20~50: a measuring instrument, the detector diameter is more than 5cm, and it has similar counting efficiency for a particles of ReA and RaC'; α reference source, 2Am or Pu source; filter membrane: stopwatch; tweezers.
6.3 Inspection before measurement
GB/T14582:93
Figure 4 Schematic diagram of the balloon sampling system
1-Sampling head: 2-Flowmeter; 3-Gas system 14-Throttle valve 5-Ring; 6-Balloon sample
Substrate sample
Figure Time program for balloon measurement
Sampling counter
Before each measurement, the sampling equipment and counting instruments must be strictly inspected. The inspection content is shown in 5.3. 6.4 Point arrangement
6.4.1 Indoor measurement
For indoor sampling measurement, the point arrangement principle and sampling conditions must meet the requirements of Appendix A (Supplement) A2, h. The air inlet is about 1.5m above the ground.
6.4.2 Outdoor measurement
For outdoor sampling measurement, the point arrangement principle and sampling conditions are the same as those in Article 5.4. 6.5 Records
The contents to be recorded during sampling are shown in Appendix A (Supplementary) A3. Operation procedures
Install the person, remove the filter membrane, and connect the sampling equipment; h
Inflate the balloon at a flow rate of 40 L/min within Q~~5 min, remove the inlet sample head and place it on the counter, and connect the balloon outlet to the vacuum pump: exhaust at a flow rate of 50 L/min within 10~14 min; measure the α radioactivity of the inlet filter membrane within 12~~15 min; measure the α radioactivity on the outlet filter membrane within 16~26 min: use formula (9) to calculate the α potential concentration:
Where Ce
-α potential concentration, J/m
GB/T 14582—93
p=Km(N—3R)
K.—Total coefficient of Markov method. J/m·Counts; Ne—Total counts of an inlet filter, let: R-background count rate, counts/min.
Use formula (10) to calculate ammonia concentration;
Crn=K,(Nr—10R)
Where: Cra
Oxygen leakage, Bg/m
Balloon scale constant, Bg/m. Counts;
Ne—Total α counts of the outlet filter, counts: R
Same as formula (9).
6.7 Determination of K
Use Kusnitz to calibrate the total coefficient Km of the Markov method6.7. 1 Calibration method
Sampling at a specified flow rate for 5min!
h, measuring the α count (Nr)c of the filter sample within 7~10min after the sampling, and performing the first α count of this sample at any time interval within 40~90min after the sampling (such as measuring for 10min), and the net α count is Ne.
Use formula (11) to calculate Km
-Kusnitz coefficient/m·count.
Where: Kk-
e. Perform at least 3 measurements and find the average value of K. 6. 7. 2 Determination of Kk
6. 7. 2. 1. Kk is determined by formula (12):
-sampling flow rate, L/min;
E——counting efficiency,;
-membrane filtration efficiency, %;
Kk* Nk
4.16×10-
[230-2T(40≤T≤70)
195 -1. 5T(70T$90)
(13）93
Figure 4 Schematic diagram of the balloon sampling system
1-Sampling head: 2-Flowmeter; 3-Gas system 14-Throttle valve 5-Ring; 6-Balloon sample
Substrate sample ...Substrate sample
Time schedule of balloon measurement
Sampling equipment and counting instruments should be strictly checked before each measurement. The inspection contents are shown in 5.3. 6.4 Point arrangement
6.4.1 Indoor measurement
For indoor sampling measurement, the point arrangement principle and sampling conditions should meet the requirements of Appendix A (Supplement) A2, h. The air inlet is about 1.5m above the ground.
6.4.2 Outdoor measurement
For outdoor sampling measurement, the point arrangement principle and sampling conditions are the same as those in Article 5.4. 6.5 Records
The contents to be recorded during sampling are shown in Appendix A (Supplementary) A3. Operation procedures
Install the person, remove the filter membrane, and connect the sampling equipment; h
Inflate the balloon at a flow rate of 40 L/min within Q~~5 min, remove the inlet sample head and place it on the counter, and connect the balloon outlet to the vacuum pump: exhaust at a flow rate of 50 L/min within 10~14 min; measure the α radioactivity of the inlet filter membrane within 12~~15 min; measure the α radioactivity on the outlet filter membrane within 16~26 min: use formula (9) to calculate the α potential concentration:
Where Ce
-α potential concentration, J/m
GB/T 14582—93
p=Km(N—3R)
K.—Total coefficient of Markov method. J/m·Counts; Ne—Total counts of an inlet filter, let: R-background count rate, counts/min.
Use formula (10) to calculate ammonia concentration;
Crn=K,(Nr—10R)
Where: Cra
Oxygen leakage, Bg/m
Balloon scale constant, Bg/m. Counts;
Ne—Total α counts of the outlet filter, counts: R
Same as formula (9).
6.7 Determination of K
Use Kusnitz to calibrate the total coefficient Km of the Markov method6.7. 1 Calibration method
Sampling at a specified flow rate for 5min!
h, measuring the α count (Nr)c of the filter sample within 7~10min after the sampling, and performing the first α count of this sample at any time interval within 40~90min after the sampling (such as measuring for 10min), and the net α count is Ne.
Use formula (11) to calculate Km
-Kusnitz coefficient/m·count.
Where: Kk-
e. Perform at least 3 measurements and find the average value of K. 6. 7. 2 Determination of Kk
6. 7. 2. 1. Kk is determined by formula (12):
-sampling flow rate, L/min;
E——counting efficiency,;
-membrane filtration efficiency, %;
Kk* Nk
4.16×10-
[230-2T(40≤T≤70)
195 -1. 5T(70T$90)
(13）93
Figure 4 Schematic diagram of the balloon sampling system
1-Sampling head: 2-Flowmeter; 3-Gas system 14-Throttle valve 5-Ring; 6-Balloon sample
Substrate sample ...Substrate sample
Time schedule of balloon measurement
Sampling equipment and counting instruments should be strictly checked before each measurement. The inspection contents are shown in 5.3. 6.4 Point arrangement
6.4.1 Indoor measurement
For indoor sampling measurement, the point arrangement principle and sampling conditions should meet the requirements of Appendix A (Supplement) A2, h. The air inlet is about 1.5m above the ground.
6.4.2 Outdoor measurement
For outdoor sampling measurement, the point arrangement principle and sampling conditions are the same as those in Article 5.4. 6.5 Records
The contents to be recorded during sampling are shown in Appendix A (Supplementary) A3. Operation procedures
Install the person, remove the filter membrane, and connect the sampling equipment; h
Inflate the balloon at a flow rate of 40 L/min within Q~~5 min, remove the inlet sample head and place it on the counter, and connect the balloon outlet to the vacuum pump: exhaust at a flow rate of 50 L/min within 10~14 min; measure the α radioactivity of the inlet filter membrane within 12~~15 min; measure the α radioactivity on the outlet filter membrane within 16~26 min: use formula (9) to calculate the α potential concentration:
Where Ce
-α potential concentration, J/m
GB/T 14582—93
p=Km(N—3R)
K.—Total coefficient of Markov method. J/m·Counts; Ne—Total counts of an inlet filter, let: R-background count rate, counts/min.
Use formula (10) to calculate ammonia concentration;
Crn=K,(Nr—10R)
Where: Cra
Oxygen leakage, Bg/m
Balloon scale constant, Bg/m. Counts;
Ne—Total α counts of the outlet filter, counts: R
Same as formula (9).
6.7 Determination of K
Use Kusnitz to calibrate the total coefficient Km of the Markov method6.7. 1 Calibration method
Sampling at a specified flow rate for 5min!
h, measuring the α count (Nr)c of the filter sample within 7~10min after the sampling, and performing the first α count of this sample at any time interval within 40~90min after the sampling (such as measuring for 10min), and the net α count is Ne.
Use formula (11) to calculate Km
-Kusnitz coefficient/m·count.
Where: Kk-
e. Perform at least 3 measurements and find the average value of K. 6. 7. 2 Determination of Kk
6. 7. 2. 1. Kk is determined by formula (12):
-sampling flow rate, L/min;
E——counting efficiency,;
-membrane filtration efficiency, %;
Kk* Nk
4.16×10-
[230-2T(40≤T≤70)
195 -1. 5T(70T$90)
(13）
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