3 ms·

What is the proper cleanup when a tritium-powered exit sign has been broken?

31 points by marcodiego 3y ago

rubatuga 3y ago
Or... you could sweep it into your nearest waste bin.
- curtis3389 3y ago
  Umm...no: >Unwanted tritium exit signs may not be put into ordinary trash; they require special disposal. Tritium exit signs that are illegally put in ordinary landfills can break and contaminate the site. Owners of buildings are responsible for ensuring the safe operation and disposal of tritium exit signs. From here: https://www.epa.gov/radtown/tritium-exit-signs https://www.epa.gov/radtown/tritium-exit-signs
  - RetroTechie 3y ago
    On a practical note: If the tritium vials / compounds included in product aren't broken, in a landfill it would just sit there, right? Tritium half-life is ~12y iirc? If it is broken: VENTILATE! Some other tritium-containing compound? Can't be collected (like, sweeped up) somehow? And ehm... ~12y half-life. Whatever gets loose isn't going to stay around 'forever'.
peter_d_sherman 3y ago
Related: https://www.epa.gov/radtown/tritium-exit-signs https://www.epa.gov/radtown/tritium-exit-signs https://en.wikipedia.org/wiki/Radioluminescence https://en.wikipedia.org/wiki/Radioluminescence https://en.wikipedia.org/wiki/Phosphor https://en.wikipedia.org/wiki/Phosphor
eternityforest 3y ago
What's the actual energy output on those? I know nothing about the physics, but from this picture (https://citylabs.net/nanotritium-betavoltaic-p200-series-package-specifications/ https://citylabs.net/nanotritium-betavoltaic-p200-series-pac...), they get 100uW from 100Ci. Assuming the glow phosphors are 25 times more efficient than their conversion process(Google says 4% for beta batteries as the first result I can find) that's 625uW of light energy. I would imagine the phosphor is not 100% efficient so it's probably less. Assuming 20% efficiency for a green LED, that's 3.125mW of electrical input to replace it with an LED. Are they really that dim??? Over 15 years, that's around 200-400Wh of electricity one would need. I wonder what's better for the environment, the tritium or the batteries one could probably use instead for similar cost, since those signs seem to be $300. I suppose the tritium is not an issue on the production side because it's a byproduct? Unless the processing has nasty effects?
- xkcd-sucks 3y ago
  eh, tritium and its decay products float off into space unless incorporated into a heavier molecule (e.g. burning concentrated tritium into water). even then hydrogens are usually pretty labile and don't bioaccumulate unlike e.g. calcium/strontium/phosphorous. so the risk of exposure is negligible except maybe in manufacturing, and the risk of environmental accumulation is also negligible. with tritium/phosphor, the brightness is super dim but more than sufficient in actual darkness. it's simple, stable under extreme environmental conditions, and there's nothing microscopic or macroscopic to break besides the containment vessel itself. it lasts for decades and fails by dimming gradually (unless the containment vessel is broken at least). not sure about exit sign construction but the little bitty capsule form factor is quite resilient.. by contrast LEDs and electronics in general seem to be less tolerant of challenges (i.e. side reactions in the battery over 10 years at elevated temperature, it gets zapped by an electrical arc etc). also the manufacturing is just as nasty and the stuff is less likely to just float off into space

31 points by marcodiego 3y ago

rubatuga 3y ago

Or... you could sweep it into your nearest waste bin.

curtis3389 3y ago
Umm...no: >Unwanted tritium exit signs may not be put into ordinary trash; they require special disposal. Tritium exit signs that are illegally put in ordinary landfills can break and contaminate the site. Owners of buildings are responsible for ensuring the safe operation and disposal of tritium exit signs. From here: https://www.epa.gov/radtown/tritium-exit-signs https://www.epa.gov/radtown/tritium-exit-signs
- RetroTechie 3y ago
  On a practical note: If the tritium vials / compounds included in product aren't broken, in a landfill it would just sit there, right? Tritium half-life is ~12y iirc? If it is broken: VENTILATE! Some other tritium-containing compound? Can't be collected (like, sweeped up) somehow? And ehm... ~12y half-life. Whatever gets loose isn't going to stay around 'forever'.

peter_d_sherman 3y ago

Related: https://www.epa.gov/radtown/tritium-exit-signs https://www.epa.gov/radtown/tritium-exit-signs https://en.wikipedia.org/wiki/Radioluminescence https://en.wikipedia.org/wiki/Radioluminescence https://en.wikipedia.org/wiki/Phosphor https://en.wikipedia.org/wiki/Phosphor

eternityforest 3y ago

What's the actual energy output on those? I know nothing about the physics, but from this picture (https://citylabs.net/nanotritium-betavoltaic-p200-series-package-specifications/ https://citylabs.net/nanotritium-betavoltaic-p200-series-pac...), they get 100uW from 100Ci. Assuming the glow phosphors are 25 times more efficient than their conversion process(Google says 4% for beta batteries as the first result I can find) that's 625uW of light energy. I would imagine the phosphor is not 100% efficient so it's probably less. Assuming 20% efficiency for a green LED, that's 3.125mW of electrical input to replace it with an LED. Are they really that dim??? Over 15 years, that's around 200-400Wh of electricity one would need. I wonder what's better for the environment, the tritium or the batteries one could probably use instead for similar cost, since those signs seem to be $300. I suppose the tritium is not an issue on the production side because it's a byproduct? Unless the processing has nasty effects?

xkcd-sucks 3y ago
eh, tritium and its decay products float off into space unless incorporated into a heavier molecule (e.g. burning concentrated tritium into water). even then hydrogens are usually pretty labile and don't bioaccumulate unlike e.g. calcium/strontium/phosphorous. so the risk of exposure is negligible except maybe in manufacturing, and the risk of environmental accumulation is also negligible. with tritium/phosphor, the brightness is super dim but more than sufficient in actual darkness. it's simple, stable under extreme environmental conditions, and there's nothing microscopic or macroscopic to break besides the containment vessel itself. it lasts for decades and fails by dimming gradually (unless the containment vessel is broken at least). not sure about exit sign construction but the little bitty capsule form factor is quite resilient.. by contrast LEDs and electronics in general seem to be less tolerant of challenges (i.e. side reactions in the battery over 10 years at elevated temperature, it gets zapped by an electrical arc etc). also the manufacturing is just as nasty and the stuff is less likely to just float off into space