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.

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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