Not Great, Not Terrible – Radioactive Items in Museums

Radiation is present in our everyday lives, whether we realise it or not. There’s always background radiation, for example, that we all get doses of every day. Then there’s examples like going for a CT-Scan or X-Ray at the doctors. But what about more uncommon methods, from areas you might visit with friends or family, like a museum? How could a museum possibly give off radiation?

Well, let me first give a little context about radiation and why it’s both fascinating and terrifying. There’s three types of radiation; alpha, beta, and gamma. Alpha is large particles consisting of Helium 4 (⁴He), which is two protons and two neutrons in a core. Beta is a single electron, and gamma is pure energy. These are all classed as “ionising radiation” as they can strip all the electrons from an atom. Alpha particles have a range of a few centimetres and can be stopped by a piece of paper. Beta particles can travel further but are stopped by a piece of metal, like aluminium. Gamma travels far and wide and is highly dangerous, with several feet of lead needed for a chance to stop it. Ionising radiation can deform human cells, cause cancers, acute radiation syndrome (ARS or just radiation poisoning) and certain death if a high enough dose. Figure 1 below shows the radiation types.

Figure 1: Types of radiation (Wikimedia Commons)

Obviously, too much gamma isn’t good, and the large beta and alpha particles can cause dangerous and deadly mutations. So what can museums do avoid this? The first thought is to just not take in anything radioactive. Sounds easy, right? But what about a smoke detector? Old aircraft instrument? A glass plate? A chunk of rock? Bananas? All these have sources of radiation. Smoke detectors often use Americium-241 (²⁴¹Am) as an alpha particle emitter which is what detectors use to detect smoke. Aircraft instruments, particularly from the 1930s through to around the ‘60s, used Radium-88 (⁸⁸Ra) as a luminant to make dials glow at night. “Uranium glass” uses uranium oxide diurinate to give glass objects a colour as well as glow under UV night. Natural granite rock can contain radioactive elements such as Potassium-40 (⁴⁰K) or Uranium-235 (²³⁵U). Bananas and Brazil nuts both contain radioactive elements, with bananas containing potassium and Brazil nuts containing radium.

Figure 2: Two potential sources of radiation. Uranium glass (top) and aircraft instruments (bottom). (Hazards in Collections, 2019)

Of course, there’s so many more examples I could bring up, like old medical equipment, trinitite (glassy residue left by tests of atomic bombs), and of course radioactive equipment from disasters like Chernobyl or atomic bomb tests. How are these things looked after, then? Well, some objects like the uranium glass and natural granite give off such little radiation in comparison to background radiation that little needs to be done for them. They are often safe to handle or have on display for lengths of time with no adverse side effects. Often things like uranium glass had, at most, 2% uranium in them and so while they register on Geiger counters, they pose no threat to members of the public or conservators.

Things like smoke detectors can be an issue, however. Since ²⁴¹Am is common in smoke detectors, it can’t be left out in the open when exposed. While the alpha particles dissipate after a few centimetres, it can release the more dangerous beta and gamma particles. For storage, therefore, they need to be securely contained in lined boxes that are air-tight, and a dosimeter needs to be on hand in the collection for monitoring whenever any radioactive object is moved or handled. Naturally, objects coming from a known disaster like Chernobyl are not accepted due to the dangerous radiation levels they still contain. For example, the firefighter’s clothes are still giving off dangerous levels of radiation in the basement of Pripyat City Hospital № 126, nearly 40 years later.

Typically, a radioactive object is not placed on display, unless its danger is negligible, such as that piece of granite or uranium glass talked about earlier. Anything that is on display will be done so with extreme caution, precision, and deliberation. Thick glass of a display case will stop alpha particles and may stop beta particles, but anything emitting dangerous gamma particles will be left in storage to avoid endangering the public.

Radioactive objects can be accepted into museum collections, and they still are every year, however they are cared for extremely carefully. As said, a dosimeter or Geiger counter is on hand to monitor radiation levels, at least one member of staff is trained in handling radioactive objects, and radiation protection advisers (RPAs) are consulted with and kept updated. Additionally, things like respirators and even full hazmat suits are also ready and available for members of staff checking or handling radioactive items in collections. Anything dangerously radioactive is disposed of carefully and under the supervision of an RPA.

Figure 3: A Geiger–Müller counter, with the display in counts per second and a cylindrical detector. (Wikimedia Commons)

Berengar Needham is currently a student on the MA Museum Studies program at the University of Leicester.

References

• Hazards in Collections (2019). Radiation. https://hazardsincollections.org.uk/radiation/keywords

• Health and Safety Executive. (1999). Radiation protection supervisors. https://www.hse.gov.uk/pubns/irp6.pdf