allRadioactive

Exploring What Happened in Bayo Canyon?

Welcome back fellow radiation nerds! Today we dive deep into what really happened in the Bayo Canyon!

Bayo Canyon is located east of Los Alamos, New Mexico and it is a place of striking natural beauty. With its breathtaking landscapes, towering cliffs, and vibrant wildlife, one might assume this area has been a peaceful retreat for ever, but in the 1940s, a series of powerful explosions shocked this place, leaving behind a legacy that endures to this day.

History

During the Manhattan Project, a team of scientists led by high explosive expert, George Kistiakowsky, was tasked with studying the behaviour of radioactive materials under extreme conditions. Their work was critical to the development of the plutonium implosion-type bomb just like the bomb Fat-Man which was later used over Nagasaki.

A total of 242 tests were conducted in Bayo Canyon, with each test using several hundred curies of radioactive materials, primarily radioactive Lanthanum-140 often referred to as “RaLa”, which has a half-life of just 40 hours , however, Lanthanum was not the only radioactive element used .

These tests continued until 1961 and in 1976, the government initiated a cleanup of the area, burying radioactive contaminants deep underground. Yet, to this day, debris can be easily found around the location of the test site with some pieces still exhibiting traces of radioactivity.

Today the Bayo Canyon has slightly elevated activity, though I’m not sure if it’s contamination from the test or is it from natural sources, as I’ve recorded the same increased activity pretty much through out my entire hike to the location of the test site.

Analysis of the samples collected

During my exploration of the canyon, I discovered around two dozen pieces, including metal shrapnel and cable wiring. When inspected closely, you can see how the intense force of the explosions tore the metal apart with ease.

From all the pieces I found, one appears to be radioactivity and clocks around 2000 CPM on my Ludlum Model 3 with a 44-9 probe at 1cm distance. This discovery was particularly intriguing, given that all radioactive Lanthanum-140 should have decayed by now. Curious to uncover its source, I conducted a gamma spectrum analysis of the sample using my RAYSID gamma spectrometer.

The analysis reveals peaks at 63, 93, and 186 keV, which are characteristic for Uranium. Given the small size of the peak at 186 keV, it’s likely that the sample contains depleted uranium instead of regular one as U-235 was in high demand for the production of the uranium bomb, Little Boy, which was later used over Hiroshima.

Conclusion

If you find yourself in Los Alamos with some time to spare, I highly recommend hiking through Bayo Canyon. Whether you’re a nuclear physics enthusiast or a casual tourist, the canyon offers stunning natural beauty, diverse wildlife, and a unique glimpse into the history of atomic bomb development. The hike is about 1.5 hours one way, so be sure to bring plenty of water and prepare accordingly!

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!

By allRadioactive, ago

Exploring Krypton 85 and its radioactivity

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. 

Krypton 85 gamma spectrum, RAYSID Gamma Spectrometer (FWHM <7%)

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.

Robotron office (Source: DNN.de)

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.

German smoke detectors and the activity of their sources (source: geigerzaehlerforum)

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.

Rundfunk RFD 70361 smoke detector source containing <18.5 MBq of Kr85

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!

By allRadioactive, ago

Why is Coal Radioactive?

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.

RAYSID Gamma Spectrometer (FWHM <7%)

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!

By allRadioactive, ago

How to calibrate and maintain your Geiger counter

Welcome back my fellow radiation nerds! Today we will dive deep into how to calibrate Geiger Counters so that they show true readings!

If you are collector of old, vintage Geiger counters then you know that they are not only they are built like tanks but also have a certain character and feel to them. Unfortunately, the calibration on them might be a bit off as a result of their ageing components. Today I want to show you how you can easily calibrate your Geiger counter so that it shows accurate readings again!

In order to do this you will need:

  • a multimeter with 2 probes and a 1G Ohm (1000M Ohm) resistor for measuring the HV
  • a pulser
  • and your Geiger counter with a cable to connect a GM probe

Firstly, you will need to check if the voltage on your meter if it is correct using a multimeter and a 1G Ohm resistor. I already made a post about it which you can find HERE.

The next step is to connect the pulser in place of the probe. Pulser will generate “clicks” at a consistent rate which will allow us to calibrate the meter. I personally use one made by GEOelectronics and I highly recommend it but others should also work fine.

Now turn on your meter and set your pulser to generate a desired amount of CPM. Make sure that the needle on the meter is showing the correct amount of CPM generated by the pulser on every scale. If it is not, then adjust the calibration potentiometer until it sits right where you want it.

Ludlum Model 3 calibration potentiometers

If your meter uses dose units such as uSv/h, then you will need to find a conversion rate from CPM to uSv/h for the Geiger tube used in your meter. THIS post by DIYGeiger covers most of the GM tubes commonly used and gives a rough conversion ratio from CPM to uSv/h. Please note that this isn’t very accurate and if possible, you should use CPM when measuring activity of a samples. Dose units work only when the meter is calibrated to the specific isotope which is being measured. In other cases, the readings can be lower or higher than in reality.

Congratulations, you have now successfully calibrated your Geiger counter! However if you are a professional and you want the most accurate calibration on your meter, then you should most probably send your meter for calibration to a professional lab but for most hobbyists, this method should be more than enough!

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!

By allRadioactive, ago

Radioactive Metro Station in Berlin

When I first moved to Berlin, someone told me that there is a radioactive metro station somewhere in the city. Since then, I was on a mission to find it but unfortunately, with little to no success… until recently.

One of the most iconic places in Berlin must be the Brandenburger Tor and only one station away from it is the Potsdamer Platz which is home to the Sony Center as well as The Mall of Berlin, but today, we are going to focus what lies underneath the ground.

A few days ago I was coming back home from work and I had to change trains at the Potsdamer Platz S-Bahn station and as I was waiting for my train, a characteristic orange colour of the tiles caught my eye. From my bag I quickly took out my trusty Terra-P Geiger counter and I brought it near the tiles and within seconds the alarm started screaming.

Interestingly, after measuring a bunch of the orange tiles, I noticed that not all of the them where radioactive. This is most probably because some of those tiles have been replaced with newer ones which do not contain radioactive elements.

A quick gamma spectroscopy of the tiles made with my RAYSID gamma spectrometer, confirmed the presence of uranium. The peak at 186 keV indicates that these tiles contain Uranium-235 which means they were produced using natural uranium and not depleted.

Although these tiles make my Geiger counter scream, they are in fact harmless. That is because they emit mainly alpha and beta radiation and standing just a half meter away from them will result in radiation dropping to normal background levels.

So next time you are going to be visiting Berlin, make sure to bring a Geiger counter with you and check out the Potsdamer Platz S-Bahn station!

By allRadioactive, ago

Radioactive Tungsten Electrodes (TIG)

Introduction

Today I want to show you an item that you can find in a hardware store and it is radioactive. Let’s take a closer look at the thoriated Tungsten electrodes!

Main information

There are three types of thoriated Tungsten electrodes with the only difference being the amount of Thorium in them. Yellow ones contain around 1% of Thorium, red contain 2% and orange contain 4%. Even though orange ones contain the highest amount of Thorium, they are actually not much more radioactive than the red ones which are the most common. Tungsten electrodes come in different sizes with the bigger ones being slightly more active. Personally, I decided to go with 3.2mm x 175mm but smaller should also work fine.

Red Tungsten Electrodes (WT20)

Isotope: 232Th

Activity: < CPM (LND 7311)

Amount: ~2%

Since the label on the box clearly states that these electrodes contain Thorium, I didn’t expected the gamma spectroscopy to show anything intresting but to my suprise, it did!

Slide to the right to see Thorium gas mantle spectrum
Slide to the Left to see Thoriated Tungsten electrodes spectrum

The main two differences between the spectrum of Tungsten electrodes and the spectrum of Thorium gas mantle are the peak at 511 keV and the peak 583 keV. Let’s start with the peak at 511 keV. It is referred to as annihilation peak and it is caused by the annihilation of a positron by its interaction with an electron. This event can occur more often in Tungsten electrodes because of their density. The peak at 583 keV is caused by Thallium 208. When Thorium decays, it emits Radon 220 which is a gas and it escapes into the air but in the case of the Tungsten electrodes, it is trapped by dense Tungsten which results in the accumulation of Radon decay products including Thallium 208.

Thorium decay chain (source: metadata.berkeley.edu)

Safety

These electrodes are often used as a check source because of how easy to find they are and their small activity which makes them relatively safe. That being said, when used for their original purpose, the dust generated by sharpening them could cause health problems in the long run if inhaled.

Fake Tungsten Electrodes

When buying these electrodes, make sure to buy branded ones because unfortunately, unbranded ones are often fake and they do not contain Thorium. I made this mistake twice and both times I received fake electrodes that weren’t radioactive.

By allRadioactive, ago

Radioactive BH-45M Switch

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.

Long exposure of BH-45M switch

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.

By allRadioactive, ago

Radioactive Cesium 137

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).

TG-36 spark gap tube containing <1 uCi of Cs-137

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.

Caesium 137 in mushrooms collected in Belarus

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.

TG-36 tube, RAYSID gamma spectrometer FWHM <8.5%

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.

TubeOriginal activity
CK1097-15< 280 pCi / 10.4 Bq
EII-43-100Unknown
TG-20A< 1 uCi / 37 kBq
TG-29Unknown
TG-30<5 uCi / 185 kBq
TG-36< 1 uCi / 37 kBq
TG-53< 5 uCi / 185 kBq
TG-77< 0.9uCi / 33.3 kBq
TG-133< 5 uCi / 185 kBq
TG-162< 5 uCi / 185 kBq
XG-1684< 1uCi / 37 kBq
Table with some of the tubes that used Cs-137

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.

By allRadioactive, ago

Radioactive Lanthanum 138

Today we will take a closer look at another naturally occurring radioactive element, Lanthanum!

Lanthanum is a rare earth element and it’s the first element in the lanthanide series. It has an atomic number of 57 and was first discovered by a Swedish chemist, Carl Gustaf Mosander in 1839 but pure Lanthanum wasn’t obtained until 1923. Today, Lanthanum is most commonly used in the production of Tungsten electrodes, scintillators and in the past, it was added to some vintage lenses.

Lanthanum Metal

LaBr3(Ce) Scintilation crystals

Lanthanum Bromide scintillation crystals are well known for their incredible resolution which measures as low as 2.2% at 662 keV and since they have a relatively low price compared to other hi resolution detectors, they are a viable option for amateur gamma spectroscopy setups. These crystals however are not perfect, due to the Lanthanum content, they are slightly radioactive themselves which causes them to self generate a characteristic background spectrum that must be removed if measuring low activity samples.

Radioactivity and gamma spectroscopy

In nature, there are two isotopes of Lanthanum, La-139 (99.91% abundance) and La-138 which has an abundance of 0.09% and it is also radioactive.

Lanthanum 138 has a very long half-life of 1.02E+11 years and its activity cannot be easily detected with a conventional Geiger counter. To do that a large scintillator must be used since it is much more sensitive.

Unfortunately, my sample of Lanthanum is pretty small and my set-up isn’t sensitive enough to detect it so I reached out to my friend Gigabecquerell who has provided a gamma spectrum of his Lanthanum sample.

Lanthanum 138 decays through electron capture or by beta emission and in both cases, it also releases a gamma-ray at 789 keV and 1436 keV.

A gamma spectroscopy reviels two peaks at 789 keV and 1436 keV which are both caused by the decay of Lanthanum 138 through electron capture or by beta emission and in both cases a gamma ray is also released.

Lanthanum 138 gamma spectrum
By allRadioactive, ago

Radioactive Cobalt 60

Cobalt 60 is a radioactive isotope of Cobalt and it is produced by neutron activation of stable Cobalt 59 in nuclear reactors. Since it has a short half-life of only 5.3 years, it does not occur in nature and all samples that exist are synthetic. A single gram of Co-60 has an activity of 44TBq and it undergoes a beta decay into an excited state of Nickel 60 which emits two gamma rays at 1173 and 1332 keV before becoming stable.

Gamma spectroscopy of Cobalt 60

One of the main uses of Cobalt 60 is in radiotherapy where cancer cells are exposed to a beam of high energy gamma radiation, effectively killing them. Its gamma rays are also used in the sterilisation of food and medical equipment and they can even be used in levelling devices and thickness gauges to detect structural errors.

Bomac 1B63A Waveguide Tube

For decades tubes have been a key component of electrical devices such as radios, amplifiers and many more. Some of these tubes contained radioactive elements which improved the ionisation process and also made them radioactive.

My sample of Co-60 is in an old Bomac 1B63A tube which was originally used in radars and it contained <1uCi of Co-60. These tubes have been manufactured in the late XX century and sadly there is no detectable activity left since almost all of Co-60 has decayed.

Dirty nukes

Unfortunately, Cobalt 60 can also be used in weapons of mass destruction. Dirty nukes or salty nukes are nuclear weapons that contain Cobalt 59 but during nuclear fission, it turns into Cobalt 60 which contaminates the surrounding area for decades. Officially, there are no countries in possession of such weapons and let’s hope that even if there are, they will never use them.

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By allRadioactive, ago