Judgment at Alcatraz

Project for the atomic bomb nicknamed ‘Fat Man’ and dropped on Nagasaki—has fallen into relative obscurity.
So maybe it should be no surprise that other nuclear threats are lingering in plain sight. Shocked? You should be.
I was… and am.
To be fair, this question is, in part, a trick question. The most prevalent radioactive isotopes are those used in medical procedures and industrial radiography (examining metal castings and forgings, and welded seams for structural integrity). One of the most common is cobalt-60. Cobalt, in its stable or non-radioactive isotopic form, is a metal used in products ranging from lithium batteries to stainless steels to super alloys that withstand high temperatures and stress—i.e., alloys used in aircraft engines. And most of the global supply of cobalt originates in the Democratic Republic of the Congo.
So, it should be no surprise that cobalt is prized as a recyclable metal. Which is the problem.
You see, slipping in a little cobalt-60 will earn a greater payment from the recycler, but those handling the reclaimed metal have no idea of the deadly material they are processing.
Since the early 80s, there have been several documented cases of cobalt-60 turning up in metal reclaiming centers. In some cases, the radioactive cobalt even made it into newly manufactured products. A particularly notorious case occurred in Taiwan. Between 1982 and 1984, reclaimed cobalt-60 was incorporated into newly manufactured rebar and used in the construction of more than two-hundred residential and other buildings in northern Taiwan and Taipei. The government never took action to condemn the buildings. More than seven-thousand people have been exposed, and most without their knowledge.
In 1983 a resident of Ciudad Juarez, Mexico, attempted to recycle about six-thousand pellets of cobalt-60. The metal so contaminated his truck that the truck was scrapped. In doing so, five-thousand metric tons of steel was contaminated. The contaminated steel was used to manufacture kitchen and restaurant table legs as well as rebar. The contaminated products were transported into the U.S. and Canada. After discovery of the incident, the Nuclear Regulatory Commission installed radiation monitors at all major crossings from Mexico into the U.S.
Other similar incidents with cobalt-60 occurred in China, Thailand, Turkey, India, and Italy, often resulting in fatalities.
In a bizarre case in 2013, a truck transporting a medical cobalt-60 source from a hospital in Tijuana was hijacked near Mexico City. Following a nationwide search, the truck was found abandoned, but the deadly cargo was missing. Fortunately, the cobalt-60 was later discovered in a nearby field. The fate of the thieves was never determined.
Every now and then medical isotopes go missing, either because of errors in record keeping or transgressions in handling the material. However, most radioactive elements used in treatment of cancer or in diagnostics, have relatively short half-lives (the aforementioned cobalt-60 being an exception). This means they quickly lose their lethality.
However, there is another peaceful and common use of radioactive isotopes that has escaped, for the most part, public scrutiny, and yet represents a clear and present danger. I am talking about Radioisotope Thermoelectric Generators—commonly called RTGs.
From the perspective of science and engineering, these are truly elegant machines with no moving parts. RTGs generate electric power from heat, making good use of the Seebeck Effect. The Seebeck Effect describes the production of an electric potential when the junction of two dissimilar metals is heated. Such a device is called a thermocouple, and a group of several thermocouples is called a thermopile. Thermocouples and thermopiles are ubiquitous, but most commonly you would encounter them in your gas water heater and kitchen oven.
If our goal is to generate electric power for a long time (such as a deep-space probe), the heat source is the trick. Decades ago, NASA determined that radioactive isotopes, which produce heat as a byproduct of the radioactive decay process, would make ideal heat sources lasting years, even decades.
Therein lies the danger as well as the potential harm. You see, satellites and deep-space probes are not the only applications requiring reliable electric power for a period of years with no maintenance. A prevalent terrestrial need is remote navigational beacons. And a very large number of such beacons have been deployed by Canada, the U.S., and the Soviet Union (now Russia) in the Arctic. RTGs have also been deployed in Eastern Europe to power remote telemetry stations.
Ordinarily, this would not be a problem at all—provided the machines were periodically attended to, and all units were tracked and disposed of appropriately at end of life.
Perhaps that would have been the case had the Soviet Union not fallen. The chaos of transitioning to a new government, causing social and economic insecurity, created an environment where details easily slipped notice and were forgotten.
RTGs of Soviet or Russian manufacture, using strontium-90 as the power source, are scattered across the far northern frontier and the former Soviet bloc nations of Eastern Europe. And these machines are not secured. Several have shown up in the most unexpected places, like the wilderness in Georgia, 50 km east of the village of Lia. There, in December of 2001, three woodcutters found two abandoned RTG cores. They were not marked as hazardous. The men had no idea what they’d found, but they appreciated the heat emanating from the devices and used them as heaters while they spent a cold night in the forest. Within hours all three men began to display symptoms of radiation poisoning—burns over their backs and hands, headache, dizziness, nausea, vomiting. One of the woodcutters ultimately died from radiation exposure.
Other incidents with RTG cores containing strontium-90 occurred in far northern Russia in 2003 and 2004.
Fortunately, plutonium as a power source has been relegated to deep space missions only, so there is no danger of it being available terrestrially. Still, strontium-90 is extremely dangerous. Chemically, strontium is very similar to calcium, and if ingested, strontium-90 localizes in bone where it irradiates the surrounding tissue. The knowledge that these RTGs are scattered about, unguarded and unaccounted for, is truly frightening.
This is the Nuclear Genie that lives on in the shadows.