• Encyclopaedia of Radioactive Isotopes

Welcome back my fellow radiation nerds! Today we will take a closer look at a radioactive isotope of lead, Lead 210!

Element Lead 208

The element Lead (Pb) is a dense, heavy metal with an atomic number of 82, making it the heaviest stable element in the periodic table. Despite its high density, Lead is surprisingly soft, which makes it easy to bend and shape. In its pure form, Lead has a silvery grey colour, similar to most metals but if it is exposed to air, it will oxidise and darken over time as a layer of lead oxide forms on its surface.

Lead has been known to humanity since the ancient times where it was a popular material thanks to its malleability and relatively low melting point of 327 °C. For example the Romans, used Lead in plumbing, cookware, and cosmetics. However, they weren’t aware of its toxicity which contributed to many health issues including neurological damage, gastrointestinal problems, and developmental delays.

Today the use of lead is much more limited to help minimise potential health risks it poses but it is still being used in some key industries including production of lead acid battles or in radiation shielding.

In nature, there are several isotopes of lead, with the most common being Lead 208, which makes up 52.4%. This is followed by Lead 206 at 24.1% and Lead 207 at 22.1%. All of these isotopes are stable, but lead also has a few naturally occurring radioactive isotopes. These isotopes, are found in the decay chains of Uranium or Thorium, and aren’t present in typical lead ore. Most of them have a pretty short half-lives ranging from a few minutes to several hours—except one: Lead 210.

Radioactive Lead 210

Lead 210 exists naturally in trace amounts as it is one of the daughter isotopes of Uranium, more precisely it is produced by the decay Polonium 214 through an alpha emission or by the beta decay of Thallium 210. It undergoes a beta decay into Bismuth 210 and it also releases a gamma ray at 47 keV and has a half-life of 22.3 years. Bismuth then undergoes a beta decays into Polonium 210 which finally decays into a stable Lead 206 by releasing an alpha particle.

Very rarely Lead 210 will undergo an alpha decay turning into Mercury 206 which then decays through a beta emission into Thallium 206 which finally decays by releasing a beta particle, turning into a stable Lead 206

Since lead 210 is the only Radon daughter isotope with long half-life, it can accumulate and build up over time in areas where high levels of radon gas are present. This is the case with my DP-63-A, which insides are still heavily contaminated with Pb-210 despite the Radium dial being removed long time ago.

My sample

My sample of Lead 210 is a bit of an unconventional one. In order to create it, I used active carbon pallets which I then exposed to a strong radon emitter and I left them sealed in a jar for over two years. After removing the radon source, the jar was highly radioactive due to all the short lived isotopes being present but after a few day, they have decayed leaving only longer lived isotopes including Lead 210 and Polonium 210 inside.

When the lid of the jar is removed, the active carbon pellets reads 500 CPM on my Ludlum Model 3 with a 44-9 probe when measured just above the opened jar. The gamma dose rate is just barely above background and my RAYSID only detects an increase of about 10 CPS when placed right next to the jar.

Gamma spectroscopy

A gamma spectroscopy of my Lead 210 revealed a clear peak at 47keV with a smaller X-ray peak to the left. This peak at 47keV can be also seen in gamma spectra of Uranium or Radium samples which makes it pretty interesting to see how peaks from parent isotopes star to disappear as we go lower in the decay chain.

Gamma spectra made with RAYSID <7% FWHM

Summary

Exploring the radioactivity of Lead 210 was a lot of fun and I certainly learned a lot about it! It definitely showed me that while radon might have a short half-life of only 3.6 days, its daughters will remain radioactive for many years to come.

If you want to find out more about Radon I recommend checking out my previous video on it, which I have linked in the description.

I want ot hear from you! Do you have any Lead 210 samples and what other radioactive isotopes should I cover in the future videos? Let me know in the comments below!

Thank you so much for reading this post, I hope you enjoyed it and learned something new! If yes, please make sure to subscribe to the email list so that you get notified when new posts are added. Also feel free to check out my Ko-Fi page where you can donate a nice cup of radioactive coffee and support my work financially.

and remember, stay active!

Welcome back fellow radiation nerds, today we dive deep into the radioactivity and uses of Krypton 85!

Krypton is a colourless, tasteless and odourless noble gas and it was first discovered in 1898 by Wiliam Ramsay and Morris Travers. It has atomic number of 36 and its most common isotope is Krypton 84, which is stable.

Kr-85 on the other hand, is radioactive and it was first discovered in 1940 by Martin Kamen and Sam Ruben, during their research involving the neutrons bombardment of stable Krypton isotopes, at the University of California, Berkeley.

Krypton-85 is predominantly produced through human activities such as nuclear fission and the reprocessing of spent nuclear fuel, however, traces of Krypton 85 are also produced naturally by the interaction of cosmic rays with a stable Krypton-84 found in Earths atmosphere.

Some of the main uses of the radioactive Krypton 85 are in arc discharge lamps and in cold-cathode voltage regulator electron tubes. Since Krypton is a gas, it can also be used to find leaks in closed systems and small defects in aircraft components.

Radioactivity & Gamma spectroscopy

Krypton-85 is a radioactive isotope with a half-life of approximately 10.76 years. It decays by beta emission, transforming into stable rubidium-85 and in the process it also releases a gamma ray with an energy of 514 keV. 

My Sample

My sample comes in the form of an old DDR smoke detector produced by Robotron RFT. The model number is 70130 and it was used in industrial complexes. The actual radioactive source is a little glass bulb originally containing 18.5MBq of Kr-85.

Since the detector is couple decades old by now, the activity of Krypton 85 decreased but it is still detectable when measured with my RAYSID gamma spectrometer. When placed on the top of the detector, RAYSID showed an activity of 136 CPS and had no problem in detecting the peak at 514 keV.

The housing of the smoke detector acts like a shield and stops most of the beta radiation, which results only in a slight increase in the activity when measuring it with my Ludlum Model 3 Meter with a 44-9 probe. This however changes when the housing is removed and the glass bulb is exposed. At 5cm my Ludlum reads 500 000 CPM and it maxes out if brought any closer. RAYSID reads a gamma dose of 0.86 uSv/h (675 CPS) at 1cm distance.

Overall I am very happy to finally get a chance to explore the radioactivity of Krypton 85 and share my experiences. I absolutely love shape and form of the source and I find it very interesting that this smoke detector uses Kr85 instead of much more common Am241. If you ever come by one of those detectors, they are a great find but be careful as the glass bulb is rather fragile and can easily break

Thank you so much for reading this post, I hope you enjoyed it and learned something new! If yes, please make sure to subscribe to the email list so that you get notified when new posts are added. Also feel free to check out my Ko-Fi page where you can donate a nice cup of radioactive coffee and support my work financially.

and remember, stay active!

NORM is an acronym for Naturally Occurring Radioactive Material and it covers, well, all radioactive material that occurs is nature. Some of the main elements that make up NORM are Uranium Thorium and Radium. Traces of these elements can be found pretty much everywhere but sometimes their accumulation can result in radioactive contamination of materials which are not usually thought as radioactive.

Why is coal radioactive

Not that long ago, a friend of mine send me a sample of coal which comes from an area near Dresden in Germany. This region is very rich in coal deposits but they are not pure. Coal easily absorbs elements that surround it and in this case, it was in close proximity to uranium which resulted in it getting contaminated and also becoming radioactive.

The sample measures 6cm by 4cm by 3 cm and reads about 2 500 CPM on a pancake probe at 1cm distance. A gamma spectroscopy made with my RAYSID gamma spectrometer, shows a clear presence of natural uranium and its decay products.

While this is an extreme example, coal can contain trace amounts of radioactive elements and burning it, will results in the release of these elements into the environment. Considering how much coal is burned to produce energy each year, it is safe to say that coal power plants produce more unregulated nuclear waste than any nuclear power plant does. It is ironic how some countries build coal power plants instead of nuclear ones since they are afraid of nuclear energy and yet coal power plants are the ones producing more unregulated nuclear waste and contaminating our environment with toxic elements.

Thank you so much for reading this post, I hope you enjoyed it and learned something new! If yes, please feel free to subscribe to the email list so that you get notified when new posts are posted. Also feel free to check out my Ko-Fi page where you can donate a nice cup of radioactive coffee and support my work financially.

and remember, stay active!

Today we will take a closer look at a radioactive, soviet switch, the BH-45M!

The production of BH-45M switches started in 1945 and continues till this day, this being said, not all of those switches are radioactive. Units produced until 1965 used radium paint but in later models, radium paint was replaced by a nonradioactive one. The very early models which were produced until early 1950s, used RaBr2 while the ones produced later used RaSO₄. BH-45M switches are mainly used in military vehicles such as tanks but can also be found in some civilian ones. These switches were produced in countries of Warsaw Pact and can be found today cheaply at antique markets.

As a result of constant exposure to nuclear radiation, the paint decays and with time it loses its radioluminaces properties. Today the glow from the switch is undetectable for human eye but a photo made with a long exposure shows that there is still little bit of glow left.

Radium is a particularly nasty element not only because of its very high activity and radio toxicity but also because it decays into a radioactive gas called radon which in large doses can be dangerous. Luckily, the switch I have is pretty well sealed and doesn’t leak too badly, so the radon emission is relatively low.

Activity and Gamma Spectroscopy

Radium painted items range in activity anywhere from few hundred CPM to hundreds of thousands depending on the amount of radium paint used. When it comes to BH-45M switches, they are definitely are on the hotter side. The one I have measures at around 220k CPM at 1cm distance on a pancake probe and 10uSv/h gamma only at 1cm distance on my RAYSID gamma spectrometer.

Just as expected, a gamma spectroscopy of the BH-45M switch shows a very characteristic gamma spectrum for Ra226 and its decay products.

Today we will explore the radioactivity and uses of Caesium 137!

Caesium is probably best known for its high reactivity and low melting point of only 28.5°C and it was first discovered in 1860 by two German scientists, Robert Bunsen and Gustav Kirchhoff. It has atomic number of 55 and has only one natural isotope, Caesium 133 which is stable. Caesium 137 on the other hand is a radioactive and it is produced by a nuclear fission of Uranium 235 and it is commonly found in nuclear waste and fallout. It has a medium-short half-life of 30.1 years and a single gram has an activity of 3.215 TBq (86.9 Ci).

Uses

Since Caesium 137 is one of the main radioactive elements found in nuclear fallout, it is very often used as a calibration source for radiation detectors. It also has many applications in the medical industry where it can be used in radio-therapy to fight cancer or to sterilise medical equipment. It can also be found in thickness gauges, flow meters and in gamma-ray well logging devices. Because Caesium 137 wasn’t produce before 1945, it can be used to date wine and detect counterfeits.

Health risks

Caesium 137 is one of the most dangerous isotopes found in nuclear fallout because of its strong gamma-rays but unlike Strontium 90, if ingested it is distributed around the body more or less evenly and it has a short biological half-life of 70 days.

Radioactive decay & gamma spectroscopy

Caesium 137 is a beta and a gamma emitter. In 94% of the cases, it emits a beta particle (511 keV) turning into a metastable Barium 137m which then emits a gamma-ray (662 keV) before becoming stable. In the remaining 6% of cases, Caesium 137 decays directly into stable Barium 137 by a beta emission (1172 keV).

Caesium 137 has a very characteristic gamma spectrum with two large peaks at 31 keV and 662 keV which make it a very popular calibration source for gamma spectrometers.

My samples

As of right now, I got two samples of Cs137. The first one is a TG-36 Spark Gap Tube produced by CP Clare. According to the date code, it was produced in the September of 1985 and it originally contained <1uCi of Cs137. Today the activity drop to <0.43uCi but it is still detectable and it measures just over 1 uSv/h on my RAYSID gamma spectrometer and about and about 450 CPM on my Ludlum Model 3 with 44-9 probe at 1cm.

My other source is made from ashes of Belarusian mushrooms which contain the fallout from Chernobyl. They clock at almost 250 CPM on my Ludlum at 1cm distance but when measured in a lead castle with my RAYSID, the activity increased only by 6.5 CPS.