Experiment - Capturing Radon progeny from Uraninite (Uranium ore)
3 days 1 hour ago - 3 days 1 hour ago #7225
by Simomax
Experiment - Capturing Radon progeny from Uraninite (Uranium ore)
This should be quite interesting to anyone that owns or is thinking of owning Uraninite (Uranium ore) sources, and anyone with a keen interest in Radon. TL;DR - Skip to the last part for safety concerns with U-238 sources and also Thorium gas mantles, Thorium dioxide.
This was a fairly well controlled experiment that was carried out at home, and using ChatGPT as my lab sidekick. The idea was to capture Radon progeny from 4.46g of Uraninite (Uranium ore) and prove the decay products. Uraninite emits Radon gas and this decays into other daughter radioisotopes, such as Pb-214, Bi-214 and Pb-210. The experiment took around 25 hours to complete, including write up and photos.
An airtight chamber (electrical project enclosure with a gasket seal) is used to house the Uraninite source, sat on a pedestal, approximately in the centre of the chamber. Above the source a layer of sellotape is suspended with the sticky side facing the source. A single layer of activated carbon pellets cover the floor of the chamber. A Radiacode 101 was initially used for the first spectrum, and then a Radiacode 103 was used for the other spectra. A NetIO-GC10 MK1 with a SBM-20 GM tube was used for detecting soft beta - β⁻. The Radiacode 101 was calibrated prior to the experiment and the Radiacode 103 calibration was confirmed before use.
Enclosure used for the experiment. An electronics project enclosure with gasket for air tight seal.
Placement of the Uraninite source and activated carbon pellets along the floor of the chamber.
A layer of sellotape was stuck to a foam board frame and held in place with friction. The sticky side of the sellotape faces the Uraninite source.
The completed enclosure, sealed tight.
As the Radon gas is emitted from the Uraninite source, it decays into other products. These products are captured on the sticky side of the sellotape as the Radon gas hits it and decays into its daughter products. The Radon gas also gets absorbed by the activated carbon, effectively trapping it, and in turn decays into its daughter products, leaving them trapped within the activated carbon.
The experiment was put together on 21/12/2025 and an initial Gamma spectrum (4 days 22 hours) was taken with the Radiacode 101 on top of the enclosure, above the Uraninite specimen. After the spectrum was captured it was left for three months for the contamination to occur. After three months another Gamma spectrum was taken using a Radiacode 103 on the outside of the enclosure, in the same manner as the initial spectrum was sampled with the Radiacode 101. These showed Gamma peaks at 354 keV (Pb-214) and 660 keV (Bi-214) and are strong indicators of Radon progeny.
Initial Gamma spectrum with Radiacode 101 sat on top of the enclosure - 4 days 22 hours.
The second Gamma spectrum sampled using the Radiacode 103, again sat on top of the enclosure in the same manner as the first Gamma spectrum - 1 day 3 hours.
After the 2nd external spectrum was sampled, Gamma spectra was taken of the sellotape and the activated carbon, as well as using a Geiger counter with SBM-20 tube to try to detect Pb-210 (β⁻ 22.3 year half life). The enclosure was opened and the sellotape carefully removed and stuck sticky side down onto a piece of clear acetate. This helps with safety/handling and will stop anything captured from contaminating other things. The enclosure was closed back up with the Uraninite source to contaminate the activated carbon some more whilst testing took place on the sellotape. The sellotape was placed onto the Geiger counter (NetIO-GC10 & SBM-20) and counts of 130cpm were obtained. This indicates the presence of Pb-214 & Bi-214 both of which are beta and gamma emitters and possibly Pb-210 and Bi-210, though their confirmation would require more precise beta energy discrimination. The other isotopes would be much more prominent, so it is impossible to tell at this stage until the other isotopes decay. The Radiacode 103 was then used to sample the sellotape for 3 days. Key findings from the spectrum are: 295 keV and 352 keV peaks indicate Pb-214 is present. 609 keV and 1120 keV peaks suggest Bi-214 is also present. Inconclusive findings of Pb-210. Some counts were obtained at ~46 keV, but not enough to confirm Pb-210. After the three days of Gamma sampling the sellotape was once again placed on the Geiger counter and nothing was detected. There was a negligible increase in counts. This indicates that the initial 130 cpm were in fact Pb-214 and Bi-214 with very short half lives - 26.8 minutes and 19.9 minutes respectively. After several hours some Pb-210 may remain, but in quantity too small for the SBM-20 to detect and the shorter lived isotopes will have decayed away.
Sellotape stuck to acetate for protection and handling.
Gamma spectrum of the sellotape once stuck down to the acetate sheet - 3 days 1 hour.
Geiger counter with SBM-20 GM tube detecting 130 cpm from the sellotape.
For the final part of the experiment, the enclosure was opened up once more and the Uraninite source removed, along with the pedestal. This made room to place the Radiacode 103 inside the enclosure with the sensor surrounded with the activated carbon. This was left for 3 days an 9 hours to sample for the spectrum. Pb-214 and Bi-214 were detected by the Radiacode 103, as expected, showing that the activated carbon had in fact absorbed the Radon gas and the daughter products formed within the activated carbon. Again, the Radiacode 103 didn't detect any noticeable Pb-210. The activated carbon was then decanted into a sealable plastic bag and placed onto the Geiger counter with SBM-20 tube. Counts of ~53 cpm (background = ~24 cpm) were obtained from the activated carbon. A MiniMonitor 5.10 Geiger counter with a Mullard MX-123 GM tube was used to sample the activated carbon with no noticeable detections being shown. The MX-123 GM tube is capable of detecting hard Beta (β⁺) and Alpha (α) radiation, but soft beta (like from Pb-210) is typically below its effective threshold. The SBM-20 GM tube is capable of detecting Gamma (γ) and hard and soft Beta (β⁺ / β⁻), and knowing the decay chain for U-238, and is still detectable several days later, this would confirm the presence of Pb-210, with a half life of ~22.3 years.
Activated carbon on the Geiger counter showing ~53 cpm some hours later
Gamma spectrum of the activated carbon - 3 days 9 hours.
And so what we have left is a bag of Pb-210 contaminated activated carbon. Effectively a soft beta, Pb-210 source, with a half life of ~22.3 years.
Experiment summary
A controlled radon progeny experiment using a sealed plastic chamber containing a 4.46 g Uraninite specimen and a base layer of 1.5 mm activated carbon pellets. The chamber remained sealed for 85 days. A layer of Sellotape was suspended above the specimen during this period to collect airborne decay products.
Upon opening the chamber, the following was observed:
Experiment time line.
Conclusion
This successfully demonstrated the accumulation and detection of radon decay progeny using both passive deposition (Sellotape) and
adsorption (activated carbon). Short-lived gamma-emitting progeny were confirmed early on, and long-lived Pb-210 was shown to persist
via beta emissions. This experiment validates the behaviour and capture of radon decay products in a sealed environment and sets a foundation for further real-time or long-tube detection studies.
Final thoughts
This was a great experiment and gave good results, much better than I expected. I now have a low level source of Pb-210. I also now have some more low level radioactive waste. I need to make better arrangements for storing this (and other waste) until such a time as it is disposed of properly. ChatGPT helped in a massive way with it's analysis, peak detection and help in creating this experiment, in a fairly safe and controlled manner. It can be done much safer and a glove box/fume hood is on the cards as a future project to facilitate in more of these kinds of experiments.
Notes on safety when collecting/handling certain sources
Uraninite is Uranium ore. U-238 decays to Radium-226 (via some other isotopes) then to Radon-222, which is released into the air. Once in the air it decays further into Pb-214, Bi-214 and Pb-210 as well as some other short lived isotopes. These isotopes, whether short lived or long lived pose a safety concern for storage of the Uraninite, in they will contaminate the surrounding area of the source. If in a container the inside of the container will become contaminated with Radon progeny, and if left out in the open it will contaminate any surface where Radon-222 decays, leaving its radioactive progeny (e.g., Pb-214, Bi-214) behind. People should be aware of this (I wasn't until this experiment) and take measures to contain the contamination, and use extra precautions when handling the source(s). It's not just fragments from the source that can cause issues with health, but also the contamination in the container of the source, but also Radon release into the air, especially if kept indoors. Simply knowing this happens is a good first step.
The same can be said with Thorium gas mantles. If they are broken, or crushed, which may happen just with handling them. When clean and intact they are fairly passive, but if cracked, burnt or degraded they will shed fine Thorium dust and emit Thoron gas (Rn-220). This decays into daughters such as Pb-212, Bi-212 and Tl-208. Thus the same care, if not more than U-238 sources should be implemented for safety.
Gamma spectra XML files are attached below.
What's next? Build a glove box/fume hood for further experiments, and maybe, just maybe, try and make a stronger Pb-210 source using the same method, only more concentrated, and then maybe crush up, add some resin and make a Pb-210 source disc. That's for later though!
This should be quite interesting to anyone that owns or is thinking of owning Uraninite (Uranium ore) sources, and anyone with a keen interest in Radon. TL;DR - Skip to the last part for safety concerns with U-238 sources and also Thorium gas mantles, Thorium dioxide.
This was a fairly well controlled experiment that was carried out at home, and using ChatGPT as my lab sidekick. The idea was to capture Radon progeny from 4.46g of Uraninite (Uranium ore) and prove the decay products. Uraninite emits Radon gas and this decays into other daughter radioisotopes, such as Pb-214, Bi-214 and Pb-210. The experiment took around 25 hours to complete, including write up and photos.
An airtight chamber (electrical project enclosure with a gasket seal) is used to house the Uraninite source, sat on a pedestal, approximately in the centre of the chamber. Above the source a layer of sellotape is suspended with the sticky side facing the source. A single layer of activated carbon pellets cover the floor of the chamber. A Radiacode 101 was initially used for the first spectrum, and then a Radiacode 103 was used for the other spectra. A NetIO-GC10 MK1 with a SBM-20 GM tube was used for detecting soft beta - β⁻. The Radiacode 101 was calibrated prior to the experiment and the Radiacode 103 calibration was confirmed before use.
Enclosure used for the experiment. An electronics project enclosure with gasket for air tight seal.
Placement of the Uraninite source and activated carbon pellets along the floor of the chamber.
A layer of sellotape was stuck to a foam board frame and held in place with friction. The sticky side of the sellotape faces the Uraninite source.
The completed enclosure, sealed tight.
As the Radon gas is emitted from the Uraninite source, it decays into other products. These products are captured on the sticky side of the sellotape as the Radon gas hits it and decays into its daughter products. The Radon gas also gets absorbed by the activated carbon, effectively trapping it, and in turn decays into its daughter products, leaving them trapped within the activated carbon.
The experiment was put together on 21/12/2025 and an initial Gamma spectrum (4 days 22 hours) was taken with the Radiacode 101 on top of the enclosure, above the Uraninite specimen. After the spectrum was captured it was left for three months for the contamination to occur. After three months another Gamma spectrum was taken using a Radiacode 103 on the outside of the enclosure, in the same manner as the initial spectrum was sampled with the Radiacode 101. These showed Gamma peaks at 354 keV (Pb-214) and 660 keV (Bi-214) and are strong indicators of Radon progeny.
Initial Gamma spectrum with Radiacode 101 sat on top of the enclosure - 4 days 22 hours.
The second Gamma spectrum sampled using the Radiacode 103, again sat on top of the enclosure in the same manner as the first Gamma spectrum - 1 day 3 hours.
After the 2nd external spectrum was sampled, Gamma spectra was taken of the sellotape and the activated carbon, as well as using a Geiger counter with SBM-20 tube to try to detect Pb-210 (β⁻ 22.3 year half life). The enclosure was opened and the sellotape carefully removed and stuck sticky side down onto a piece of clear acetate. This helps with safety/handling and will stop anything captured from contaminating other things. The enclosure was closed back up with the Uraninite source to contaminate the activated carbon some more whilst testing took place on the sellotape. The sellotape was placed onto the Geiger counter (NetIO-GC10 & SBM-20) and counts of 130cpm were obtained. This indicates the presence of Pb-214 & Bi-214 both of which are beta and gamma emitters and possibly Pb-210 and Bi-210, though their confirmation would require more precise beta energy discrimination. The other isotopes would be much more prominent, so it is impossible to tell at this stage until the other isotopes decay. The Radiacode 103 was then used to sample the sellotape for 3 days. Key findings from the spectrum are: 295 keV and 352 keV peaks indicate Pb-214 is present. 609 keV and 1120 keV peaks suggest Bi-214 is also present. Inconclusive findings of Pb-210. Some counts were obtained at ~46 keV, but not enough to confirm Pb-210. After the three days of Gamma sampling the sellotape was once again placed on the Geiger counter and nothing was detected. There was a negligible increase in counts. This indicates that the initial 130 cpm were in fact Pb-214 and Bi-214 with very short half lives - 26.8 minutes and 19.9 minutes respectively. After several hours some Pb-210 may remain, but in quantity too small for the SBM-20 to detect and the shorter lived isotopes will have decayed away.
Sellotape stuck to acetate for protection and handling.
Gamma spectrum of the sellotape once stuck down to the acetate sheet - 3 days 1 hour.
Geiger counter with SBM-20 GM tube detecting 130 cpm from the sellotape.
For the final part of the experiment, the enclosure was opened up once more and the Uraninite source removed, along with the pedestal. This made room to place the Radiacode 103 inside the enclosure with the sensor surrounded with the activated carbon. This was left for 3 days an 9 hours to sample for the spectrum. Pb-214 and Bi-214 were detected by the Radiacode 103, as expected, showing that the activated carbon had in fact absorbed the Radon gas and the daughter products formed within the activated carbon. Again, the Radiacode 103 didn't detect any noticeable Pb-210. The activated carbon was then decanted into a sealable plastic bag and placed onto the Geiger counter with SBM-20 tube. Counts of ~53 cpm (background = ~24 cpm) were obtained from the activated carbon. A MiniMonitor 5.10 Geiger counter with a Mullard MX-123 GM tube was used to sample the activated carbon with no noticeable detections being shown. The MX-123 GM tube is capable of detecting hard Beta (β⁺) and Alpha (α) radiation, but soft beta (like from Pb-210) is typically below its effective threshold. The SBM-20 GM tube is capable of detecting Gamma (γ) and hard and soft Beta (β⁺ / β⁻), and knowing the decay chain for U-238, and is still detectable several days later, this would confirm the presence of Pb-210, with a half life of ~22.3 years.
Activated carbon on the Geiger counter showing ~53 cpm some hours later
Gamma spectrum of the activated carbon - 3 days 9 hours.
And so what we have left is a bag of Pb-210 contaminated activated carbon. Effectively a soft beta, Pb-210 source, with a half life of ~22.3 years.
Experiment summary
A controlled radon progeny experiment using a sealed plastic chamber containing a 4.46 g Uraninite specimen and a base layer of 1.5 mm activated carbon pellets. The chamber remained sealed for 85 days. A layer of Sellotape was suspended above the specimen during this period to collect airborne decay products.
Upon opening the chamber, the following was observed:
- The Sellotape sample produced ~130 CPM on an SBM-20 Geiger counter, confirming deposition of short-lived radon daughters.
- Radiacode 103 analysis of the Sellotape showed clear gamma peaks from Pb-214 and Bi-214, validating successful progeny capture.
- After a few days, Geiger counter readings from the Sellotape returned to background levels (~24 CPM), confirming the decay of short-lived progeny.
- The activated carbon, after 3 days and 9 hours of gamma collection with the Radiacode 103, showed distinct Pb-214 and Bi-214 gamma peaks.
- Charcoal placed in a plastic bag caused SBM-20 counts to rise from ~24 to ~53 CPM, suggesting retention of low-energy beta emitters.
- A test using the Mullard MX-123 tube (Mini Instruments 5.10) showed no significant increase in counts, confirming that the remaining radiation is soft beta (likely Pb-210), below the MX-123's sensitivity.
Experiment time line.
Conclusion
This successfully demonstrated the accumulation and detection of radon decay progeny using both passive deposition (Sellotape) and
adsorption (activated carbon). Short-lived gamma-emitting progeny were confirmed early on, and long-lived Pb-210 was shown to persist
via beta emissions. This experiment validates the behaviour and capture of radon decay products in a sealed environment and sets a foundation for further real-time or long-tube detection studies.
Final thoughts
This was a great experiment and gave good results, much better than I expected. I now have a low level source of Pb-210. I also now have some more low level radioactive waste. I need to make better arrangements for storing this (and other waste) until such a time as it is disposed of properly. ChatGPT helped in a massive way with it's analysis, peak detection and help in creating this experiment, in a fairly safe and controlled manner. It can be done much safer and a glove box/fume hood is on the cards as a future project to facilitate in more of these kinds of experiments.
Notes on safety when collecting/handling certain sources
Uraninite is Uranium ore. U-238 decays to Radium-226 (via some other isotopes) then to Radon-222, which is released into the air. Once in the air it decays further into Pb-214, Bi-214 and Pb-210 as well as some other short lived isotopes. These isotopes, whether short lived or long lived pose a safety concern for storage of the Uraninite, in they will contaminate the surrounding area of the source. If in a container the inside of the container will become contaminated with Radon progeny, and if left out in the open it will contaminate any surface where Radon-222 decays, leaving its radioactive progeny (e.g., Pb-214, Bi-214) behind. People should be aware of this (I wasn't until this experiment) and take measures to contain the contamination, and use extra precautions when handling the source(s). It's not just fragments from the source that can cause issues with health, but also the contamination in the container of the source, but also Radon release into the air, especially if kept indoors. Simply knowing this happens is a good first step.
The same can be said with Thorium gas mantles. If they are broken, or crushed, which may happen just with handling them. When clean and intact they are fairly passive, but if cracked, burnt or degraded they will shed fine Thorium dust and emit Thoron gas (Rn-220). This decays into daughters such as Pb-212, Bi-212 and Tl-208. Thus the same care, if not more than U-238 sources should be implemented for safety.
Gamma spectra XML files are attached below.
What's next? Build a glove box/fume hood for further experiments, and maybe, just maybe, try and make a stronger Pb-210 source using the same method, only more concentrated, and then maybe crush up, add some resin and make a Pb-210 source disc. That's for later though!
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