Radioactive histories Part 1 - Nuclear Batteries
I love nuclear physics. I have always been fascinated by it. For me though there is the history of nuclear and atomic physic's. Its got a rich and somewhat checkered past, throughout its development there have always been, 'bumps' in its road.
- A brief breakdown
- The russian problem
- Orphan sources
- The Lia Radiological Incident
- Personal nuclear safety
One aspect of nuclear 'things' I like is something called an RTG or Radioisotopic Thermoelectric Generator. (RTG for short). Its basically a very dangerous nuclear battery. The very dangerous bit is I think what draws me to anything Nuclear, you have to have a healthy respect of it, and treat everything you do in the field with care, otherwise it will bite you back when you least expect it. During late 1945 for example an experiment was conducted at Los Alamos nuclear test facility (the birth place of the atomic bomb) where a core of Radioactive plutonium was being fooled around with (quite literally fooled around with), inside something called the Demon Core (that name should tell you all you need to know) , the process involved trying to get the core to go 'critical' by increasing and decreasing the gap between the two radioactive sources with the end of a flat headed screw driver. Now when you work in the nuclear or atomic science field and say the words, highly radioactive sources, criticality and flat headed screw driver, if red flags are not raised in your head, put down what ever it is you are working on and go find another job, in a field where you are not allowed access to nuclear material. Uh and by the way the result of that 'experiment' which was nicknamed Tickling the dragon was the eradiation of four scientists resulting in life long inflictions and the death (by horrible means) of the scientist performing the "experiment with a screw driver", so that outcome should tell you what we are working with here. Back to RTG's
The radioisotope thermoelectric generator (RTG) is a type of power source that has been used for space missions and other applications since the 1960s. The first RTG was developed by the Atomic Energy Commission (AEC) in the United States in the late 1950s, and it was used to power satellites and other spacecraft. The RTG works by converting the heat generated by the decay of radioactive isotopes into electricity, using thermoelectric materials. This technology has been used for many high-profile space missions, including the Viking Mars landers, the Galileo Jupiter mission, and the New Horizons Pluto mission. Despite concerns over the safety and environmental impact of using radioactive materials in space, the RTG remains a valuable and reliable source of power for many space exploration missions. Before we go any further lets first look at how an RTG works, because I think it's important to know.
A brief break down of how an RTG works
An RTG generates electricity through the use of a thermoelectric material that converts the heat released by the decay of a radioactive isotope into electrical power. The radioactive isotope typically used in an RTG is plutonium-238, which has a half-life of 88 years and releases alpha particles as it decays. The alpha particles collide with the atoms in the thermoelectric material, causing them to vibrate and release heat.
The thermoelectric material used in an RTG is typically made of a combination of two metals, such as bismuth telluride or lead telluride, that have different electron transport properties. One metal is a good conductor of electrons, while the other is a poor conductor. When the thermoelectric material is heated by the decay of the plutonium-238, a temperature gradient is created between the two metals. This gradient causes electrons to flow from the hot metal to the cold metal, creating an electrical current.
The electrical power produced by an RTG is typically low, with a typical output of a few watts to a few hundred watts. This limits the applications of RTGs to situations where only a small amount of power is needed, but where it is difficult or impossible to provide power by other means. Examples of such applications include remote weather stations, space probes, and deep sea sensors.
One of the main advantages of RTGs is their long life and high reliability. Because they do not rely on moving parts or complex machinery, they are much less prone to failure than other types of power generators. They also have a long operating life, with many RTGs continuing to function for decades after their installation.
However, one of the main concerns associated with RTGs is the potential environmental impact of the radioactive isotopes used in their operation. While the isotopes used in RTGs are typically enclosed in a protective casing, there is still a risk of contamination if the casing is breached. As a result, the use of RTGs is heavily regulated by government agencies such as the International Atomic Energy Agency.
So now you know how they work, lets look at our main focus of this article.
Russia's problem
In the 1960s, the Soviet Union was faced with the daunting task of providing power to remote regions in Siberia and the Arctic. These areas were often hundreds of miles away from the nearest city or infrastructure, making conventional power sources such as coal-fired plants or hydroelectric dams impractical and expensive to build. The Soviet government recognized that they needed an alternative solution, and turned to a new technology that had been developed in the United States: the radioisotope thermoelectric generator (RTG).
The Soviet Union's first experiments with RTGs began in the early 1960s, with the installation of the first Soviet RTG at the Vize Island weather station on the coast of the Arctic Ocean in 1961. Prior to this, the weather station had relied on batteries for power, which had to be changed every few months by a helicopter crew. The RTG proved to be a much more reliable and efficient source of power, operating continuously for years without maintenance or refueling.
Over the following decades, the Soviet Union continued to use RTGs for a wide range of applications in remote and harsh environments. These included powering navigational beacons, lighthouses, remote monitoring stations, and even spacecraft such as the Lunokhod moon rovers. RTGs were also used in the Soviet Union's nuclear-powered icebreaker fleet, providing auxiliary power to onboard systems.
Today, Russia remains a leading user of RTGs, with a long history of innovation and expertise in this technology. Russian RTGs have been used in a variety of space missions, including the Mars 6 and Venera 13 probes, as well as for powering remote lighthouses and weather stations in the country's vast and rugged northern regions. The use of RTGs has proved to be a valuable and reliable solution for providing power to remote and inaccessible locations, and Russia's expertise in this technology continues to be in demand for both terrestrial and extraterrestrial applications.
This lent to a massive problem when the Soviet Union collapsed, something called Orphan sources.
Orphan sources
An orphan source is a term used to describe a radioactive source that has been lost or abandoned and whose location and ownership are unknown, kind of like a broken arrow only not a nuclear weapon, just a lump of material, spewing out neutrons, energy waves and particles at almost the speed of light, with no off switch. This can happen in a number of ways, such as when a device containing a radioactive source is lost or stolen, or when a source is discarded improperly.
The risk posed by orphan sources is significant because they can potentially expose people to ionizing radiation, which can cause serious health effects such as radiation sickness, cancer, and genetic mutations. The danger is particularly high when the source is not properly shielded or when it is used in an uncontrolled setting.
Orphan sources can also pose a security risk, as they can be used in the production of radiological weapons or as part of terrorist activities.
To prevent the risks posed by orphan sources, various international organizations and governments have established regulations and guidelines for the control and management of radioactive materials, including the tracking and disposal of radioactive sources. These efforts aim to ensure that radioactive sources are used safely and that they are properly managed throughout their lifecycle, from manufacture to disposal.
So you guessed it, with all these orphan sources scattered around the decaying remains of the USSR, it was only a matter of time before an incident occurred involving one of these orphans.
The Lia Radiological Incident December 2001
The LIA radiological accident occurred on December 2, 2001, in the Lia district of Tbilisi, Georgia. The accident involved an abandoned Soviet-era Radiological Thermoelectric Generator (RTG) that had been used to power a remote lighthouse on the coast of the Black Sea.
The RTG contained a highly radioactive Strontium-90 (Sr-90) source, which was encased in a shielded container to prevent its release into the environment. However, the container was damaged, and the source was exposed. The RTG was then left abandoned in a forested area in the Lia district.
In 2001, two individuals found the RTG and removed the shielding from the source in an attempt to sell the valuable metal casing. This resulted in their exposure to high levels of ionizing radiation, and they subsequently developed radiation sickness.
The Georgian government was notified of the incident and took steps to secure the RTG and prevent further exposure. The individuals involved in the incident were hospitalized, and a team of experts was sent to the site to assess the situation and clean up the area.
The LIA radiological accident highlighted the dangers associated with abandoned or mishandled radioactive sources, particularly those containing highly radioactive isotopes such as Strontium-90. It underscored the importance of proper handling and disposal of such sources and the need for effective regulatory frameworks to prevent accidents and respond to emergencies.
This is just one example, there are several examples available on-line which document how someone has just stumbled across an orphan source while digging up there garden (a terrifying prospect!) in fact in Lithuania there is actually a help line you can call if you think you've dug up one of these things.
It's also worth noting that the International Atomic Energy Agency estimates some 2500 Orphan sources are still unaccounted for across the former USSR states, and on a yearly basis discovers on average between 30 and 50!
Personal nuclear safety
TDS principal
Nuclear physics is a complex subject, however personal nuclear safety is not, and its something we can all learn and keep in mind in the unlikely event we ever get caught up in some kind of nuclear incident. There are 2 principals of nuclear safety I want to introduce you too, and hopefully they will stick!
Time Distance Shielding
Time, Distance & shielding or TDS for short, is a principal to reduce exposure to harmful radioactive sources, which constantly emit (remember there is no off switch)
Time reducing the amount of time you spend near a source will reduce the amount of dose you receive (that one is kind of obvious)
Distance Radioactivity spreads out in every direction from its source. Try and imagine its like light (by case and point it IS light, just at a much higher frequency in the case of gamma waves) , the further away you get the less expose, so every meter matters!
Shielding Radiation can be slowed down or in some cases stopped as it passes through material, for example Alpha particles can be stopped by something as thin as a piece of paper. Gamma waves can be blocked by lead, concrete can stop Neutrons (They are the worst!) so put anything you can between you and a source. So the rule goes
TDS - LESS MORE MORE
Time Distance Shielding, Less time as possible, the most distance as you can and the most shielding as possible.
ALARA principal
Alara stands for As Low As Reasonably Achievable and is a principal again to reduce exposure. If you HAVE to put yourself in front of a source you do as much as you can through TDS to ensure you receive the lowest possible dose as is reasonable to achieve. So:
- Don't take chances
- Don't hang around (run!)
- Don't do unnecessary tasks
- Don't get curious
- Don't assume that the danger has passed.
- Do do everything you can to Limit Time, Increase distance and Increase shielding.
One final point worth noting
Radiation is invisible
People think that radioactive things glow, they don't unless you put specific ones near something phosphorus, or put them underwater (something cool called Cherenkov radiation), in reality Radioactive sources have no taste, smell, feeling (apart from being warm to the touch) or visual indicator, so never assume the absence of clues means all is clear!
I will do some more articles about nuclear physics I think but for now I will leave you with this.. Below is a picture of a small source of Cobalt-60 quite a nasty isotope, the instructions on the front of the source casing make alot of sense, just drop it and run!
