Radioactive sources are made by inserting a stable (non-radioactive) isotope of the desired material into a nuclear reactor and allowing enough time for neutron absorption to make that particular element radioactive. Another technique is to process spent nuclear fuel and separate out the desired radioactive isotope. Yet another is to bombard a sample in a particle accelerator, such as a cyclotron - although this last technique will only yield small quantities of material.
The vast majority of strong radioactive sources are made from Cobalt-60, Cesium-137, or Iridium-192. Each of these are quite lethal gamma emitters when they are not shielded against. Cesium also emits very hot beta radiation, so it's potentially quite a bit worse than the others. Sources like these are used for cancer treatment, or to sterilize medical equipment - even simple and hardy micro-organisms cannot survive the harsh radiation these sources emit. Radioactive sources are also used to make images of welds in very thick piping systems - piping that even an X-ray could not penetrate.
Here's what gets my goat though: These things are exceedingly dangerous. It shouldn't be too hard to keep tabs on this stuff and keep it out of the wrong hands. ...And yet it happens fairly often.
Here is one recent example. Synopsis: A truck driver was asleep along a highway in Mexico, when he was awakened by men at gunpoint. The truck was stolen along with the cargo. The cargo was a shielded container with a Co-60 source for treating cancer patients. When the truck was located, the container had been broken into and the Co-60 source removed.
Here is another example. Synopsis: Workers at a paper mill in Vologodskaya Oblast, Russia reported on 1 September 2003 that a device containing the radioactive isotope cesium-137 had gone missing from a factory in the city of Sokol sometime during the summer months. The instrument, known as a BGI-75A, has a total mass of 85 kg, but it was not reported how much cesium the device contains. The Sokol region Chief of Police Sergey Turkin said the device was repaired in 2000, which may mean the radioactive core was replaced at that time with a fresh cesium-137 source. The plant's chief metrologist, Viktor Undozerov, said the instrument poses a danger only if one comes into close contact with it. The police are continuing to search for the stolen device.
Another very recent example. This one is a neutron source. Nasty. Synopsis: Oilfield truck loses the source in transit to a job. Source is missing for a month, while Halliburton, Law Enforcement, and the NRC frantically search for it. Don't leave a lethal item sitting on the fender when you drive off...
Probably the worst event. This one needs to be told in full (Courtesy of Wikipedia):
The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, at Goiânia, in the Brazilian state of Goiás, after an old radiotherapy source was stolen from an abandoned hospital site in the city.
Abandonment at the Hospital:
The Instituto Goiano de Radioterapia (IGR), a private radiotherapy institute in Goiânia, was just 1 km northwest of Praça Cívica, the administrative center of the city. It moved to its new premises in 1985, leaving behind a cesium-137-based teletherapy unit that had been purchased in 1977.
The fate of the abandoned site was disputed in court between IGR and the Society of Saint Vincent de Paul, the owner of the premises. On September 11, 1986, the Court of Goiás stated it had knowledge of the abandoned radioactive material in the building.
Four months before the theft, on May 4, 1987, Saura Taniguti, then director of Ipasgo, the institute of insurance for civil servants, used police force to prevent one of the owners of IGR, Carlos Figueiredo Bezerril, from removing the objects that were left behind. Figueiredo then warned the president of Ipasgo, Lício Teixeira Borges, that he should take responsibility "for what would happen with the cesium bomb".
The court posted a security guard to protect the hazardous abandoned equipment. Meanwhile, the owners of IGR wrote several letters to the National Nuclear Energy Commission, warning them about the danger of keeping a teletherapy unit at an abandoned site, but they could not remove the equipment by themselves once a court order prevented them from doing so.
Theft of the Source:
On September 13, 1987, the guard in charge of daytime security, Voudireinão da Silva, did not show up to work, using a sick day to attend a cinema screening of Herbie Goes Bananas with his family.
The same day, "scavengers" Roberto dos Santos Alves and Wagner Mota Pereira illegally entered the partially demolished facility, found the teletherapy unit – which they thought might have some scrap value – and placed it in a wheelbarrow, taking it to Alves's home, about 0.6 kilometres north of the clinic. There, they began dismantling the equipment.
That same evening, they both began to vomit. Nevertheless, they continued in their efforts. The following day, Pereira began to experience diarrhea and dizziness and his left hand began to swell. He soon developed a burn on this hand in the same size and shape as the aperture - he eventually had partial amputation of several fingers.
On September 15, Pereira visited a local clinic where his symptoms were diagnosed as the result of something he had eaten, and he was told to return home and rest. Alves, however, continued with his efforts to dismantle the equipment, which was now sitting under a mango tree in his back yard. In the course of this effort, he eventually freed the caesium capsule from its protective rotating head. His prolonged exposure to the radioactive material led to his right forearm becoming ulcerated, requiring amputation.
The Source is partially broken:
On September 16, Alves succeeded in puncturing the capsule's aperture window with a screwdriver, allowing him to see a deep blue light coming from the tiny opening he had created. He inserted the screwdriver and successfully scooped out some of the glowing substance. Thinking it was perhaps a type of gunpowder, he tried to light it, but the powder would not ignite. The exact mechanism by which the light was generated was not known at the time the IAEA report was written, though it was thought to be either fluorescence or Cerenkov radiation associated with the absorption of moisture by the source.
The Source is sold and dismantled:
On September 18, Alves sold the items to a nearby scrapyard. A scrapyard employee came to the house, loaded the contents into a wheelbarrow, transported them to the yard, and unloaded them. That night, the owner of the scrapyard, Devair Alves Ferreira, who lived next door, went into the garage and noticed the blue glow from the punctured capsule.
Thinking the capsule's contents were either valuable or even supernatural, he immediately brought it into his house. Over the next three days, he invited friends and family to view the strange glowing substance and offered a reward to anyone who could free it from the capsule. He mentioned that he intended to make a ring out of it for his wife.
On September 21 at the scrapyard, a friend of Ferreira's succeeded in freeing several rice-sized grains of the glowing material from the capsule using a screwdriver. He shared some of these with his brother, claimed some for himself, and the rest remained in the hands of Devair Alves Ferreira, who began to share it with various friends and family members. That same day, his wife, 37-year-old Gabriela Maria Ferreira, began to fall ill. On September 25, 1987, Devair Alves Ferreira sold the scrap metal to a second scrapyard.
Ivo and his daughter: (this is the saddest part of this awful event)
The day before the sale to the second scrapyard, on September 24, Ivo, Devair's brother, successfully scraped some additional dust out of the source and took it to his house a short distance away. There he spread some of it on the cement floor. His six-year-old daughter, Leide das Neves Ferreira, later ate a sandwich while sitting on this floor. She was also fascinated by the blue glow of the powder, applying it to her body and showing it off to her mother. Dust from the powder fell on the sandwich she was consuming; she eventually absorbed 1.0 GBq, total dose 6.0 Gy, which is roughly equal to 13 Sv, more than a fatal dose even with treatment.
Gabriela Maria Ferreira notifies the authorites:
Gabriela Maria Ferreira had been the first to notice that many people around her had become severely sick at the same time. Her actions from that point on probably saved lives. She first suspected the culprit was a beverage they had shared, but an analysis of the juice showed nothing untoward. On September 28, 1987 — 15 days after the item was found - Gabriela went with one of her scrapyard employees to the rival scrapyard which was then in possession of the materials. She reclaimed them and transported them by bus in a plastic bag to a hospital.
There, physician Paulo Roberto Monteiro rightly suspected that it was dangerous. He placed it in his garden on a chair to increase the distance between himself and the materials. Because the remains of the source were kept in a plastic bag, the level of contamination at the hospital was low.
Radioactive Contaminatin Confirmed:
In the morning of September 29, 1987 a visiting medical physicist, Walter Mendes Ferreira (no relation to the aforementioned family; "Ferreira" is a common surname equivalent to "Smith"), used a scintillation counter borrowed from NUCLEBRAS (a national government agency which is involved in the nuclear fuel cycle, including searching for uranium ore) to confirm the presence of radioactivity. He spent most of the day confirming the dangerous levels of radiation and persuading the authorities to take immediate action. The city, state, and national governments were all aware of the incident by the end of the day, and the accident response started that evening.
About 130,000 people overwhelmed hospitals. Of those, 250 people, some with radioactive residue still on their skin, were found, through the use of Geiger counters, to be contaminated. Eventually, 20 people showed signs of radiation sickness and required treatment.
Devair Ferreira himself survived despite receiving 7 Gy of radiation. He died in 1994 of cirrhosis aggravated by depression and binge drinking.
A great deal of cleanup was necessary afterwards; several houses were razed and buried, and tons of topsoil removed. The biological waste of victims who had become contaminated was treated and the radioactive cesium was removed from that. They were injected with Prussian Blue dye (which reacts chemically with Cesium and is expelled in the waste). The remnants of the source were siezed and the (now decontaminated) container is on display.
This is a horrific and very sad story, but it seems like every year somebody attempts a repeat :(