Nuclear Switch Locator

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Yes, I know... the title is kind of an exaggeration but not quite :) This instructable aim to solve a problem that troubled humans since the invention of the electric light: how do you find a light switch in the dark? "Just buy an illuminated light switch!" you will say... but where's the fun in that?

I came up with a solution that requires a 3D printer, a little bit of blue tack and a couple of... radioactive gas filled vials.

These sealed glass vials are internally coated with a phosphor material and filled with tritium, a radioactive isotope of hydrogen that emits beta particles (electrons). Tritium emits electrons through beta decay and, when they interact with a phosphor material, light is emitted through the process of phosphorescence: they will glow continuously for about 20 years!

The overall process of using a radioactive material to excite a phosphor and ultimately generate light is called radioluminescence.

Supplies:

This is it!

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Step 1: Let's Do It!

Building this device is extremely easy and will require just a few minutes:

  • download the 3D model (available as STL or STEP file should you want to modify it).
  • print the 3D model.
  • insert a tiny amount of blue tack into the slots that will host the vials in order to secure them
  • insert the vials in the slots, gently pushing them. They should not protrude from the surface.
  • put some bluetack on the back of the 3D printed part.
  • secure your nuclear switch locator on the switch plate and...

...FIAT LUX! Job done

For the next 20 years you will be able to find your light switch without staining the wall around it randomly moving your hands it in the dark... :)

Step 2: Safety and Legislation

Safety

A 2007 report by the UK government's Health Protection Agency Advisory Group on Ionizing Radiation declared the health risks of tritium exposure to be double than previously set by the International Commission on Radiological Protection, but encapsulated tritium lighting devices, typically taking the form of a luminous glass tube embedded in a thick block of clear plastic, prevent the user from being exposed to the tritium at all unless the device is broken apart.

Tritium presents no external beta radiation threat when encapsulated in non-hydrogen-permeable containers due to its low penetration depth, which is insufficient to penetrate intact human skin. However, GTLS devices do emit low levels of X-rays due to bremsstrahlung. The primary danger from tritium arises if it is inhaled, ingested, injected, or absorbed into the body. This results in the absorption of the emitted radiation in a relatively small region of the body, again due to the low penetration depth. The biological half-life of tritium—the time it takes for half of an ingested dose to be expelled from the body—is low, at only 12 days. Tritium excretion can be accelerated further by increasing water intake to 3–4 liters/day.

Direct, short-term exposure to small amounts of tritium is mostly harmless. If a tritium tube breaks, one should leave the area and allow the gas to diffuse into the air. Tritium exists naturally in the environment, but in very small quantities.

Legislation

Because tritium is used in boosted fission weapons and thermonuclear weapons (though in quantities several thousand times larger than that in a keychain), consumer and safety devices containing tritium for use in the United States are subject to certain possession, resale, disposal, and use restrictions. In the US, devices such as self-luminous exit signs, gauges, wristwatches, etc. that contain small amounts of tritium are under the jurisdiction of the Nuclear Regulatory Commission, and are subject to possession, distribution, and import and export regulations found in 10 CFR Parts, 30, 32, and 110. They are also subject to regulations for possession, use, and disposal in certain states. Luminous products containing more tritium than needed for a wristwatch are not widely available at retail outlets in the United States.

They are readily sold and used in the UK and US. They are regulated in England and Wales by environmental health departments of local councils. Tritium lighting is legal in most of Asia and Australia.

(courtesy of Wikipedia)

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    19 Discussions

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    lewinskys

    13 days ago

    How dangerous are these "Radioactive" tubes? If someone breaks it are we talking a miniature Chernobyl incident? Or will I get radiation treatments for my cancer every time I go home? :P

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    hombremagneticolewinskys

    Reply 13 days ago

    Don't worry, nothing so tragic... but you are likely to generate a black hole.


    /s

    :)

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    UnstoppableDrew

    23 days ago

    For those buying in the USA, I found a vendor on Amazon but they offer them in 3 different lengths, so be sure to pick the right size (22.5mm).
    I would second the suggestion though to come up with a 3d-printed switchplate design that incorporates the tubes, rather than sticking it on top.

    1 reply
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    AnandM54

    23 days ago

    It seems huge risks making at home.....rather than I bought a radioactive switch to dark....

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    Lee73

    25 days ago

    Fun idea - make them using one vial each though, and you get 2 switches lit.... I'm astounded from the spiel that tritium lighting is legal in Australia....

    1 reply
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    Omega0397

    25 days ago

    I love the idea, I think tritium tubes are very cool and I've toyed with the idea of trying to work them into something before! I like the light switch idea, but my only question, is why not just print a whole switch plate that contains the necessary slots for the tubes? I think there are some plain light switches on thingiverse that could me modified to do this. No putty needed then. Again, very cool idea.

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    hombremagneticoOmega0397

    Reply 25 days ago

    Thanks Omega0397! I think it's a good suggestion... I should give it a try...

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    drlexluthor

    25 days ago

    My wife, Ph.D. in Chemistry, says that she won't allows those in our home the risk is too great. She would recommend the same for anyone considering it. The tiniest defect or micro fracture from assembly or installation or damaged while hanging on the wall for any reason would expose you and your family to.... but other than that it is a very cool project, I like it! Thanks for the instructable!

    3 replies
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    Captain_Nemodrlexluthor

    Reply 25 days ago

    That's just what your wife wants you to think. The real reason she doesn't want them in the house is because she thinks you will spend a fortune buying dozens of them.

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    Omega0397drlexluthor

    Reply 25 days ago

    If Tritium stored in vessels like this was that dangerous, I don't think they would be putting them in high end watches, key chains, and for any average Joe to buy on Amazon. That being said, I wouldn't want to break one, and I'm thankful that the author included some good warnings!

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    hombremagneticodrlexluthor

    Reply 25 days ago

    Thanks! I also have a PhD, Chemical and Energy technologies. Even breaking the vial the risk caused by the tritium is negligible. You should be more worried of the broken glass :) Anyone is entitled to their own opinion of course...

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    LaurentM

    25 days ago on Step 2

    So you spent £24 + 3D printing material/time for the convenience of finding a light switch in the dark???

    3 replies
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    Lee73LaurentM

    Reply 25 days ago

    You realise the filament for this would cost a few cents?

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    hombremagneticoLaurentM

    Reply 25 days ago

    yes I did! For the benefit of mankind as a whole! :o)

    ...

    (ahem...)

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    LaurentMhombremagnetico

    Reply 25 days ago

    LOL. If you wanted to be even more overkill I'd advise your very own butler to light up a torch on the light switch so you can see it :)