• Question: This may seem silly, but in your work, how do you work on the radioactive materials, what protection do you use, what do you do while there?

    Asked by to Thomas, Clara, Simon on 12 Mar 2014. This question was also asked by .
    • Photo: Thomas Elias Cocolios

      Thomas Elias Cocolios answered on 12 Mar 2014:

      There are several type of radioactivity and you handle them differently. Some at very intense in contact, but armless is handled with gloves, or wearing white overalls (check my last picture in my profile!). Some are penetrating through almost everything and you need several cm of lead, or meters of concrete/soil to shield yourself from it.

      Then, there is the question of exposure: you have external exposure (i.e. radioactivity in a room) and internal exposure (something you have breathed in, something you have eaten, an injection at the hospital, …). The latter is the most dangerous because you cannot get away from it!

      In general, we work with the ALARA principle: As Low As Reasonably Achievable. We programme our work to minimise the amount of time we spend near radioactive stuff, we make sure we wear appropriate gear (e.g. white overall, disposable gloves, mask with carbon filters).

      On top of that, we carry with us dosimeters. Those are small badges, the size of an iPhone, that record how much radioactivity we are exposed to. There are two kinds: the immediate read-back monitors (which screams if you are in a hot spot so that you don’t stick around!) and the passive monitors, that are read once a month to keep track of long-term exposure.

      I can say that after 10 years in the business, I am never been exposed to more than the average background level of radiation!

    • Photo: Simon Albright

      Simon Albright answered on 20 Mar 2014:

      Not silly in the slightest!

      In my work I don’t come into contact with radioactive material, although the banana I just ate was quite radioactive…

      As Thomas says, the way you handle radiation depends on what it is. The three most well known types of radiation are Alpha, Beta and Gamma:

      Alpha particles are helium nuclei, 2 protons + 2 neutrons and can be stopped by a sheet of paper. In practice they won’t make it past the outer most layer of your skin but you should wear gloves anyway.

      Beta particles are high energy electrons and they need something more, generally a bit of metal, to stop them.

      Gamma rays are very high energy photons (particles of light). These need some lead to stop them, and the really high energy ones need a lot of it.

      One of the hardest one to stop is actually neutrons, they behave in a really weird way. If you have a neutron source a block of lead won’t do much at all, you’re better off with a block of polythene (the stuff they make plastic bags with). Fortunately neutrons only come from a few things, like Uranium and Plutonium.

    • Photo: Clara Nellist

      Clara Nellist answered on 20 Mar 2014:

      This is a very good question! And an important point to consider when working with radioactive material.

      Actually, the ATLAS detector and the Large Hadron Collider get so radioactive from the new particles that we create that we have to wait some time, about a week or even up to a month after it is switched off before we can go anywhere near it. We call it letting the equipment ‘cool down’. After this, it is fine to go near the machine, but we have to wear the dosimeters that Thomas mentioned.

      We also keep track of who is going into areas that we send particle beams to. This is because while the beam is off, it’s safe to be in those areas, but when we turn the beam on, it is dangerous. So we have keys that people have to take into the area with them. When they leave they return the keys. If the keys haven’t all been returned, we can’t switch on the beam, because we know that there is still someone there.

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