Hydrogen - 3
Hydrogen-3 is a commonly used radionuclide with a half-life of 12.3 years, emitting only beta particles with a maximum energy of 0.019 MeV (Million Electron Volts) and an average energy of 0.0057 MeV. The beta particles from H-3 travel a maximum of 6 mm. in air.
Concerns
The major concern with using H-3 is that it cannot be easily monitored during it's use, therefore, special precautions are needed to keep the work environment clean. The regular use of wipe testing is the only way to insure that your work space is not contaminated. Contamination on the skin will not likely cause a significant dose to the dead layer of skin, however, it could lead to the internal absorption of H-3. The maximum permissible body burden to the whole body is 1 millicurie.
Shielding
Glass and plastic are the best shields for beta particles from H-3.
Detection
A tiny drop of contamination containing H-3 can be easily detected with a wipe test from a liquid scintillation counter. A Geiger counter will not detect the presence of H-3.
Equipment / supplies
- The following equipment and supplies must be available:
- a liquid scintillation detector.
- disposable latex or plastic gloves.
- full-length lab coat.
- containers for radioactive waste.
- pipettes dedicated to the use of H-3.
- commercial decontaminate, i.e. DuPont's "Count Off".
Safety rules
- If the following safety precautions are used, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for H-3 handling.
- Full-length lab coats must be worn by all persons who handle H-3.
- Protect the skin of your hands from becoming contaminated from spills by wearing two pairs of disposable gloves.
- Never pipette H-3 by mouth.
- Only use pipettes which have been dedicated to your specific use of H-3. Pipettes will easily become contaminated and therefore, should not be shared with others.
- If you have reason to believe that your gloves are contaminated, immediately dispose of them in the radioactive waste container
Post-use procedures
- After handling H-3
- Conduct a wipe test and count the wipes in a Liquid Scintillation counter:
- Check all equipment, centrifuges, water baths for contamination.
- If any contamination is found, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
- Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is H-3, maximum cpm found, and the date you measured the level.
- Check the work bench and floor.
- If contamination is found, it can usually be removed easily with "Count Off". If it cannot be removed, contact the RSO to obtain shielding materials.
- Inform your fellow lab workers if any unremovable contamination is found.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store waste temporarily in specially marked containers.
- Send a Radiation Contamination Survey Report to the RSO.
- Call the RSO if you have any questions about where to survey, or how to fill out the form.
- Wash your hands thoroughly.
- Bring the waste to the RSO frequently. Do not let it pile up. The RSO accepts waste every Friday. Call 656- 2570 for an appointment.
Carbon - 14
Carbon-14 is a commonly used radionuclide with a half-life of 5,730 years, emitting only beta particles with a maximum energy of 0.156 MeV (Million Electron Volts) and an average energy of 0.049 MeV. The beta particles from C-14 travel a maximum of 22 cm.
Concerns
The major concern with using C-14 is that it cannot be easily monitored during it's use, therefore, special precautions are needed to keep the work environment clean. The regular use of wipe testing is the only way to insure that your work space is not contaminated. Contamination on the skin will not likely cause a significant dose to the dead layer of skin, however, it could lead to the internal absorption of C-14. The maximum permissible body burden to the whole body is 0.4 millicurie.
Shielding
Glass and plastic are the best shields for beta particles from C-14.
Detection
A tiny drop of contamination from C-14 can be easily detected with a wipe test from a Liquid Scintillation Counter. Most Geiger Counters will not efficiently detect the presence of C-14.
Equipment / supplies
The following equipment and supplies must be available:
- a Liquid Scintillation Detector
- disposable latex or plastic gloves
- a full-length lab coat
- radioactive waste receptacle
- pipettes dedicated to the use of C-14
- commercial decontaminate, i.e. Dupont's "Count Off"
Safety rules
If the following safety precautions are used, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for C-14 handling.
- Full-length lab coats must be worn by all persons who handle C-14.
- Protect your hands from becoming contaminated from spills by wearing two pairs of disposable gloves.
- Never pipette C-14 by mouth.
- Only use pipettes which have been dedicated to your specific use of C-14.
- Pipettes will easily become contaminated and therefore, should not be shared with others.
- If you have reason to believe that your gloves are contaminated, immediately dispose of them in the radioactive waste container.
Post-use procedures
After handling C-14
- Conduct a wipe test and count the wipes in a Liquid Scintillation counter.
- Check all equipment, centrifuges, water baths for contamination.
- If any contamination is found, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
- Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is C-14, maximum cpm found, and the date you measured the level.
- Check the work bench and floor.
- If contamination is found, it can usually be removed easily with "Count Off". If it cannot be removed, contact the RSO to obtain shielding materials.
- Inform your fellow lab workers if any unremovable contamination is found.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store the waste temporarily in containers marked with labels "Radioactive Waste-Do Not Empty". These labels are available in the RSO.
- Send a Radiation Contamination Survey Report to the RSO.
- Call the RSO if you have any questions about where to survey, or how to fill out the form.
- Wash your hands thoroughly.
- Bring the waste frequently to the RSO. We accept waste every Friday. Call 656-2570 to make an appointment.
Phosphorus - 32
Phosphorus-32 is a commonly used radionuclide with a half-life of 14.3 days, emitting beta particles with a maximum energy of 1.71 MeV (Million Electron Volts). The beta particles travel a maximum of 20 feet in air. See Appendix A for information on the rate at which P-32 decays.
Concerns
The major concerns with using P-32 are:
- Surface radiation exposure to the skin of the hands. A drop of contamination containing 1 microcurie of P-32 on 1 cm2 area of the skin produces a radiation dose of 6,000 millirems / hour. This means that the quarterly NRC limit of 12,500 millirems to the skin would be reached in 2 hours and 5 minutes and the annual NRC limit of 50,000 millirems would be reached in just 8 hours and 20 minutes. One microcurie = 2.22 x 10E6 dpm (disintegrations per minute)
- Radiation exposure in air over an open vial. The dose rate at the opening of a vial containing 1 millicurie of P-32 can be as high as 26,000 millirems per hour. This means that the quarterly NRC limit of 12,500 millirems for the hands would be reached in 28 minutes.
- Working with P-32 orthophosphate in high concentrations. Using orthophosphate poses significant problems because of the large activity and high concentrations (i.e., 5 millicuries in 10 lambda !). If you can avoid using them, please do so. Our experience at UVM has shown that laboratories using pre-labelled P-32 (dATP, dCTP, ATP, etc.) in activities of 0.25 and 0.5 millicuries have had little or no safety problems. Using lower concentrations is very desirable. Most companies will provide lower concentrations if requested. The cost of using pre-labelled materials or lower concentrations is higher but the return in safety more than offsets the additional cost.
Shielding
Plexiglass (lucite) is the best shield for beta particles from P-32. When more than 1 millicurie of P-32 is handled, a sufficient number of x-rays (bremmstrahlung) may be formed to require Lead foil to be added to the exterior of the shield. The beta particles travel a maximum of 3.1 mm. in glass, 6.7 mm. in lucite, and 8 mm. in tissue.
Detection
A tiny drop of contamination of P-32 can be easily detected with a Geiger Counter.
Equipment / supplies
The following equipment and supplies must be available:
- A Geiger Counter sensitive to beta particles
- We recommend the Ludlum Model 3 or an equivalent with a pancake style G-M detector. Also, another excellent survey meter is Ludlum Model 3-98 which will not only detect the beta particles from P-32 but also the bremmstrahlung (secondary x-ray) radiation
- 3/8" or 1/2" plexiglass benchtop shield
- These are available from many lab equipment vendors such as RPI, VWR, Fisher, etc. and cost $150 -$250. The Instrument Model Facility (IMF) Office at UVM can also custom make one for you
- If you are going to handle more than 1 millicurie, we recommend the 1/2" thickness
- disposable latex or plastic gloves
- Film badge and ring badge
- Full-length lab coat.
- Plexiglass containers for radioactive waste
- These are available from many lab equipment vendors such as RPI, VWR, Fisher, etc.
- Pipettes dedicated to the use of P-32.
- Plastic safety glasses.
- Commercial decontaminate, i.e. DuPont's "Count Off".
Safety rules
If the following safety rules are followed, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for P-32 handling.
- Place the plexiglass shield near a wall (not toward another work area on the other side of the bench) away from the main flow of traffic in the lab.
- All persons handling P-32 must wear a ring badge on the hand which is most frequently used to handle vials, samples, pipettes, etc. containing P-32.
- Full-length lab coats must be worn by all persons who handle P-32.
- Protect the skin of your hands from becoming contaminated by wearing two pairs of disposable gloves.
- A Geiger counter must be in operation during the experiment, and at other times.
- To avoid contaminating the detector, place a thin sheet of plastic (i.e., Saran Wrap) around the detector
- Place all vials and test tubes containing P-32 behind a 3/8" or 1/2" thick plexiglass shield.
- Check the radiation level in front of the shield to determine if Lead foil should be added to block out the x-rays (called bremstrahlung) formed by the beta particles interacting with the plexiglass.
- Do not work directly over an open container of P-32.
- Never pipette P-32 by mouth.
- Only use pipettes which have been dedicated to your specific use of P-32.
- Pipettes will easily become contaminated and should be checked frequency and therefore, should not be shared with others.
- Use the Geiger Counter to check your gloves frequently for contamination.
- If contamination is found, immediately dispose of the gloves in the radioactive waste container
Post-use procedures
After handling P-32
- Use the Geiger Counter to check your hands, shoes, clothing, work bench, floor, centrifuges, and water baths for contamination.
- If any contamination is found on your shoes and/or clothing, contact the RSO. You will likely have to remove it temporarily to clean or store until the radiation decays to background.
- If any contamination is found on your hands, wash thoroughly with soap and water. This will usually be sufficient to remove the surface contamination. If it does not, contact the RSO for assistance.
- If any contamination is found on the work bench, floor, or lab equipment, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment. Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is P-32, maximum cpm found, and the date you measured the level.
- If contamination cannot be removed from the floor, contact the RSO to obtain shielding materials.
- Inform your fellow lab workers if any unremovable contamination is found.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store the waste temporarily in plexiglass containers or other containers which are sufficient to absorb P-32's beta particles.
- Send a Radiation Contamination Survey Report to the RSO.
- Call the RSO if you have any questions about where to survey, or how to fill out the form.
- Wash your hands thoroughly after using P-32.
- Bring the waste to the RSO frequently. Do not let it pile up. The RSO accepts waste every Friday. Call 656-2570 for an appointment.
still want this below, need to make table
APPENDIX A
DECAY RATE OF P-32
Days Elapsed---Activity Remaining---Decay Factor
0----------------------100.0 ------------------1.00
1---------------------- 95.3 ------------------0.953
2---------------------- 90.8 ------------------0.908
3---------------------- 86.5 ------------------0.865
4---------------------- 82.4 ------------------0.824
5---------------------- 78.5 ------------------0.785
6---------------------- 74.8 ------------------0.748
7---------------------- 71.2 ------------------0.712
8---------------------- 67.8 ------------------0.678
9---------------------- 64.6 ------------------0.646
10---------------------- 61.6 ------------------0.616
11---------------------- 58.7 ------------------0.587
12---------------------- 55.9 ------------------0.559
13---------------------- 53.2 ------------------0.532
14---------------------- 50.7 ------------------0.507
15---------------------- 48.3 ------------------0.483
16---------------------- 46.0 ------------------0.460
17---------------------- 43.8 ------------------0.438
18---------------------- 41.8 ------------------0.418
19---------------------- 39.8 ------------------0.398
20---------------------- 37.9 ------------------0.379
21---------------------- 36.1 ------------------0.361
22---------------------- 34.4 ------------------0.344
23---------------------- 32.2 ------------------0.328
24---------------------- 31.2 ------------------0.312
25---------------------- 29.7 ------------------0.297
26---------------------- 28.3 ------------------0.283
27---------------------- 27.0 ------------------0.270
28---------------------- 25.7 ------------------0.257
29---------------------- 24.5 ------------------0.245
30--------------------- 23.3 ------------------0.233
:---------------------------------------------------
143 (10 half-lives)------ 0.1 ------------------0.001
For example, if your vial contained 500 microcuries of P-32 on 7/1/04, the amount of activity remaining on 7/8/04 (7 elapsed days) would be:
Activity x Decay Factor
= 500 microcuries x 0.712 = 356 microcuries
Phosphorus - 33
Phosphorus-33 is becoming more commonly used radionuclide with a half-life of 25.4 days, emitting only beta particles with a maximum energy of 0.249 MeV (Million Electron Volts) and an average energy of 0.083 MeV. The beta particles from P-33 travel a maximum of 46 cm in air.
Concerns
The major concern with using P-33 is that it cannot be easily monitored during it's use, therefore, special precautions are needed to keep the work environment clean. The regular use of wipe testing is the only way to insure that your work space is not contaminated. Contamination on the skin will not likely cause a significant dose to the dead layer of skin, however, it could lead to the internal absorption of P-33. The maximum permissible body burden to the whole body is 3 millicurie.
Shielding
Glass and plastic are the best shields for beta particles from P-33.
Detection
A tiny drop of contamination from P-33 can be easily detected with a wipe test from a Liquid Scintillation Counter. Most Geiger Counters will not efficiently detect the presence of P-33.
Equipment/Supplies
The following equipment and supplies must be available:
- a Liquid Scintillation Detector
- disposable latex or plastic gloves
- a full-length lab coat
- radioactive waste receptacle
- pipettes dedicated to the use of P-33
- commercial decontaminate, i.e. DuPont's "Count Off"
Safety Rules
If the following safety precautions are used, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for P-33 handling.
- Full-length lab coats must be worn by all persons who handle P-33.
- Protect your hands from becoming contaminated from spills by wearing two pairs of disposable gloves.
- Never pipette P-33 by mouth.
- Only use pipettes which have been dedicated to your specific use of P-33.
- Pipettes will easily become contaminated and therefore, should not be shared with others.
- If you have reason to believe that your gloves are contaminated, immediately dispose of them in the radioactive waste container
Post-Use Procedures
After handling P-33:
- Conduct a wipe test and count the wipes in a Liquid Scintillation counter:
- Check all equipment, centrifuges, water baths for contamination.
- If any contamination is found, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
- Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is P-33, maximum cpm found, and the date you measured the level.
- Check the work bench and floor.
- If contamination is found, it can usually be removed easily with "Count Off". If it cannot be removed, contact the RSO to obtain shielding materials.
- Inform your fellow lab workers if any unremovable contamination is found.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store the waste temporarily in containers marked with labels "Radioactive Waste-Do Not Empty". These labels are available in the RSO.
- Send a Radiation Contamination Survey Report (PDF) to the RSO.
- Call the RSO if you have any questions about where to survey, or how to fill out the form.
- Wash your hands thoroughly.
- Bring the waste frequently to the RSO. We accept waste every Friday. Call 656-2570 to make an appointment.
Sulfur - 35
Sulfur-35 is a commonly used radionuclide with a half-life of 87.4 days, emitting only beta particles with a maximum energy of 0.167 MeV (Million Electron Volts) and an average energy of 0.049 MeV. The beta particles from S-35 travel a maximum of 24 cm. in air.
The above properties are very similar to those of C-14.
Concerns
The major concern with using S-35 is that it's presence cannot be monitored during it's use, since most Geiger Counters will not be able to detect S-35. Special precautions are needed to keep the work environment clean. The regular use of wipe testing is the only way to insure that your work space is not contaminated. Contamination on the skin will not likely cause a significant dose to the dead layer of skin, however, it could lead to the internal absorption of S-35 if there are cuts in the skin. The maximum permissible body burden for S-35 set by the NRC for the whole body is 400 microcuries.
Shielding
Glass and plastic are the best shields for beta particles from S-35.
Detection
A tiny drop of contamination from S-35 can be easily detected with a wipe test from a Liquid Scintillation Counter.
Equipment / supplies
- The following equipment and supplies must be available before handling S-35:
- liquid scintillation detector.
- disposable latex or plastic gloves.
- full-length lab coat.
- radioactive waste receptacle
- pipettes dedicated to the use of S-35.
- commercial decontaminate, i.e. DuPont's "Count Off"
Safety rules
If the following safety precautions are used when handling S-35, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for S-35 handling.
- Wear a full-length lab coat.
- Wear two pairs of disposable gloves to protect your hands from becoming contaminated from spills.
- Never pipette S-35 by mouth.
- Only use pipettes which have been dedicated to your specific use of S-35.
- Pipettes will easily become contaminated and therefore, should not be shared with others.
- If you have reason to believe that your gloves are contaminated, immediately dispose of them in the radioactive waste container
Post-use procedures
- Conduct a wipe test on all work benches, floor, equipment, centrifuges, and water baths.
- Count the wipes in a Liquid Scintillation counter:
- If contamination is found:
- Use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
- Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is S-35, maximum cpm found, and the date you measured the level.
- Inform your fellow lab workers if any unremovable contamination is found.
- Send aRadiation Contamination Survey Report to the RSO
- Call the RSO if you have any questions about where to survey, or how to fill out the form.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store the waste temporarily in marked containers.
- Wash your hands thoroughly.
- Bring the waste to the Radiation Safety Office on Fridays. Call 656-2570 for an appointment.
- S-35 waste will be stored by the RSO until it has decayed sufficiently to be disposed by the RSO.
Chromium - 51
Chromium-51 is a commonly used radionuclide with a half-life of 27.7 days, emitting gamma rays with a maximum energy of 0.320 MeV (Million Electron Volts). See Appendix A for the decay rate information for Cr-51.
Concerns
The major concern with using Cr-51 is radiation exposure in air over an unshielded vial. The dose rate at the opening of an unshielded vial containing 1 millicurie of Cr-51 can be 180 millirems per hour.
One millicurie = 2.22 x 109 dpm (disintegrations per minute)
This means that the quarterly NRC limit of 18,250 millirems for the hands would be reached in 101 hours.
The quarterly limit of 1,250 millirems for the whole body (assume 3 feet from the vial) would be reached in 62,500 hours.
Shielding
Lead foil or lead bricks are the best shields for gamma rays from Cr-51. The half value layer for Cr-51 gamma rays in Lead is 1.7 mm., i.e. every 1.7 mm. of Lead reduces the Cr-51 gamma ray beam by 50%.
Detection
A tiny drop of contamination containing Cr-51 can be easily detected with a survey meter that has a Sodium Iodide (NaI) detector.
Equipment / supplies
The following equipment and supplies must be available:
- Geiger Counter with a Sodium Iodide crystal.
- We recommend the Ludlum Model 3-98 or an equivalent.
- Lead foil or bricks for shielding.
- Lead bricks are available from many companies and usually cost $25 - $35 each. The Instrument Model facility (IMF) Office at UVM also has them.
- Lead foil is fairly inexpensive.
- Disposable latex or plastic gloves.
- Film badge and ring badge.
- Full-length lab coat.
- radioactive waste receptacle
- Pipettes dedicated to the use of Cr-51.
- Commercial decontaminate, i.e. DuPont's "Count Off".
Safety rules
If the following safety precautions are used, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for Cr-51 handling.
- Place the Lead shielding near a wall (not toward another work area on the other side of the bench) away from the main flow of traffic in the lab.
- All persons in the laboratory must wear a whole body film badge when in the lab, even those who are not handling Cr-51.
- All persons handling Cr-51 must wear a ring badge on the hand which is most frequently used to handle vials, samples, pipettes, etc. containing Cr-51.
- Full-length lab coats must be worn by all persons who handle Cr-51.
- Protect your hands from becoming contaminated from spills by wearing two pairs of disposable gloves.
- A Geiger Counter must be in operation during the experiment, and preferably at all other times.
- To avoid contaminating the detector, place a thin sheet of plastic (i.e., Saran Wrap) around the detector
- Place all vials and test tubes containing 51Cr behind a Lead brick shield.
- Check the radiation level in front of the shield to determine if additional Lead foil should be added.
- Do not work directly over an open container of Cr-51.
- Never pipette Cr-51 by mouth.
- Only use pipettes which have been dedicated to your specific use of Cr-51. (Pipettes will easily become contaminated and therefore, should not be shared with others.)
- Check your gloves frequently for contamination with a Geiger Counter. (If contamination is found, immediately dispose of the gloves in the radioactive waste container.)
Post-use procedures
After handling Cr-51
- Use the Geiger Counter to check your hands, lab coat, shoes, clothing, work bench, floor, centrifuges, water baths, and other lab equipment.
- If any contamination is found on your shoes and/or clothing, contact the Radiation Safety Office (RSO). You will likely have to remove the item temporarily until the radiation decays. The RSO has some disposable clothing that you can wear home. We do not have any disposable shoes.
- If any contamination is found on your hands, wash thoroughly with soap and water. This will usually be sufficient to remove the surface contamination. If it does not, contact the RSO for assistance.
- If any contamination is found on work spaces, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
- Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is Cr-51, maximum cpm found, and the date you measured the level.
- If contamination cannot be removed, contact the RSO to obtain shielding materials. Inform your fellow lab workers if any unremovable contamination is found.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store the waste temporarily in containers which are sufficient to absorb Cr-51's gamma rays.
- Send a Radiation Contamination Survey Report to the RSO.
- Call the RSO if you have any questions about where to survey, or how to fill out the form.
- Wash your hands thoroughly.
- Bring the waste to the RSO on Fridays. Call 656-2570 for an appointment. The RSO will store the waste until it has decayed sufficiently to be disposed.
still want this below, need to make table
APPENDIX A
DECAY RATE OF Cr-51
Days Elapsed % of Activity Remaining Decay Factor
•
• 0 100.0 1.00
• 1 97.5 0.975
• 5 88.2 0.882
• 10 77.9 0.779
• 15 68.7 0.687
• 20 60.6 0.606
• 25 53.5 0.535
• 27 50.9 0.509
• 28 49.6 0.496
• 30 47.2 0.472
• 35 41.7 0.417
• 40 36.8 0.368
• 45 32.4 0.324
• 50 28.6 0.286
• 55 25.3 0.253
• 60 22.3 0.223
• 65 19.7 0.197
• 70 17.4 0.174
• 75 15.3 0.153
• 80 13.5 0.135
• 85 11.9 0.119
• 90 10.5 0.105
• 95 9.3 0.093
• 100 8.2 0.082
• 105 7.2 0.072
• 110 6.4 0.064
• 115 5.6 0.056
• 120 5.0 0.050
• 125 4.4 0.044
• :
• 278 (10 half-lives) 0.1 0.001
•
For example, if your vial contained 500 microcuries of Cr-51 on 7/1/90, the amount of activity remaining on 7/16/90 (15 elapsed days) would be: Activity x Decay Factor
• = 500 microcuries x 0.687 = 344 microcuries
•
Iodine - 125
Iodine-125 is a commonly used radionuclide with a half-life of 60 days, emitting gamma rays with a maximum energy of 0.035 MeV (Million Electron Volts). See Appendix A for the decay rate information for I-125.
Concerns
The major concern with using I-125 is Radiation exposure in air over an unshielded vial. The dose rate at the opening of an unshielded vial containing 1 millicurie of I-125 can be 1,400 millirems per hour.
One millicurie = 2.22 x 109 dpm (disintegrations per minute)
This means that the quarterly NRC limit of 18,250 millirems For the hands would be reached in 13 hours.
The quarterly NRC limit of 1,250 millirems for the whole body (assume 3 feet from the vial) would be reached in 7,440 hours.
Shielding
Lead foil is the best shield for gamma rays from I-125. The half value layer for I-125 gamma rays in Lead is 0.02 mm., i.e. every .02 mm. of Lead reduces the I-125 gamma ray beam by 50%.
Detection
A small drop of contamination containing I-125 can be easily detected with a survey meter with a Sodium Iodide (NaI) Detector.
Equipment / supplies
The following equipment and supplies must be available:
- Portable radiation detector with a Sodium Iodide crystal. (We recommend the Ludlum Model 3-98 or an equivalent)
- Lead foil for shielding. Lead foil is available from many vendors and the cost is very reasonable.
- Disposable latex or plastic gloves.
- Film badge and ring badge.
- Full-length lab coat.
- Radioactive waste receptacle.
- Pipettes dedicated to your use of I-125.
- Commercial decontaminate, i.e. DuPont's "Count Off".
Safety rules
If the following safety precautions are used, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for I-125 handling.
- Place the shielding near a wall (not toward another work area on the other side of the bench) away from the main flow of traffic in the lab.
- All persons in the laboratory must wear a whole body film badge when in the lab, even those who are not handling I-125.
- All persons handling I-125 must wear a ring badge on the hand which is most frequently used to handle vials, samples, pipettes, etc. containing I-125.
- Full-length lab coats must be worn by all persons who handle I-125.
- Protect your hands from becoming contaminated from spills by wearing two pairs of disposable gloves.
- A detector must be in operation during the experiment, and preferably at all other times. To avoid contaminating the detector, place a thin sheet of plastic (i.e., Saran Wrap) around the detector
- Place all vials and test tubes containing I-125 behind a Lead foil shield. Check the radiation level in front of the shield to determine if additional Lead foil should be added.
- Do not work directly over an open container of I-125.
- Never pipette I-125 by mouth.
- Only use pipettes which have been dedicated to your specific use of I-125. Pipettes will easily become contaminated and therefore, should not be shared with others.
- Check your gloves frequently for contamination with a Geiger Counter. If contamination is found, immediately dispose of the gloves in the radioactive waste container
Post-use procedures
After handling I-125
- Use the Geiger Counter to check your hands, lab coat, shoes, clothing, centrifuges, water baths, work bench and floor.
- If any contamination is found on your shoes and/or clothing, contact the RSO. You will likely have to remove the item temporarily until the radiation decays. The RSO has some disposable clothing that you can wear home. We do not have any disposable shoes.
- If any contamination is found on your hands, wash thoroughly with soap and water. This will usually be sufficient to remove the surface contamination. If it does not, contact the RSO for assistance.
- If any contamination is found, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
- Place the towels in the radioactive waste receptacle.
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is I-125, maximum cpm found, and the date you measured the level.
- If contamination is found, it can usually be removed easily with "Count Off". If it cannot be removed, contact the RSO to obtain shielding materials.
- Inform your fellow lab workers if any unremovable contamination is found.
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
- Store the waste temporarily in containers which are sufficient to absorb I-125's gamma rays.
- Send a Radiation Contamination Survey Report to the RSO. (Call the RSO if you have any questions about where to survey, or how to fill out the form.)
- Wash your hands thoroughly.
- Bring the waste to the Radiation Safety Office frequently. We accept waste every Friday. Please call 656-2570 for an appointment.
Any questions about these procedures ? Call the Radiation Safety Office, 656-2570
still want this below, need to make table
DECAY RATE OF I-125
Days Elapsed % of Activity Remaining Decay Factor
0 100.0 1.00
10 89.1 0.891
20 79.4 0.794
30 70.7 0.707
40 63.0 0.630
50 56.1 0.561
60 50.0 0.500
70 44.5 0.445
80 39.7 0.397
90 35.4 0.354
100 31.5 0.315
110 28.1 0.281
120 25.0 0.250
:
600 (10 half-lives) 0.1 0.001
For example, if your vial contained 500 microcuries of 125I on
7/1/90, the amount of activity remaining on 7/11/90 (10 elapsed
days) would be:
Activity x Decay Factor
= 500 microcuries x 0.891 = 446 microcuries