A discussion on the true safety of Tritium Vials

[Ben H]

Hi All,

I'm starting this thread in order to put together as much information as possible about the radiation produced by tritium vials in order to identify whether they could pose a risk to health after long term exposure.

Don't get me wrong I love these things, and I have a Marathon GPM watch with 14 tritium tubes in, and a Titanium bead with 6 blue tubes. The watch doesn't concern me, with several millimeters of steel between me and the tubes. The bead as a different matter. I originally had this on a lanyard on my pocket organiser (penknife, torch, pen), but a nagging feeling that I should do some research before having something radioactive in my pocket all day every day.

That brings us here. There are a lot of people on the internet, including the organisations that sell these things, that state that the radiation produced by the Tritium is completely harmless as Tritium only produces beta particles which do not have enough energy to get through the glass walls of the vial, and if they did they wouldn't be able to get through the outer layers of the skin.

Unfortunately it is not as simple as this as when these particles strike the phosphor coating, and the glass of the vial, they rapidly decelerate causing Bremsstrahlung X-Rays. This is also fairly well known but this is where information seems to start fading. I haven't been able to find any conclusive, scientific information about whether or not that these X-Rays could pose a risk to health over long periods.

If anyone does know of studies, or calculations proving the safety of these vials please feel free to point me in the right direction. If not...

I believe however it shouldn't be too difficult to calculate. We can measure the energy of the x-rays (Once my the bits of my Gamma Spectrometer arrive), and use that to calculate the penetration depth of skin and muscle tissue.
We can also calculate the increase in exposure of that area of skin compared to background.

I have done some napkin calculations (which may be totally wrong) but seem to suggest that the radiation produced over time is fairly significant:

- Using my cheap GMC-300 Geiger (Not particularly sensitive) counter my average background reads around 15cpm 0.1uS/h
- Introducing the tritium bead bring the reading up to an average of 30cpm 0.2uS/h (but a maximum of 45cpm)
- Blocking the bead with a few layers of Aluminium foil doesn't seem to reduce the count much, suggesting that all of this reading is from X-Rays
- Taking the average increase, lets assume the bead produces 15cpm 0.1uS/h

- In a year, assuming 12h/day carrying in a pocket = 0.438mS per year (but for around 1cm2 of skin next to the bead)
- The UK average exposure is 2.7 millisieverts / year (but this is for the whole body)

Now here I'm not sure about the maths, so feel free to correct me:

If 2.7mS/y is for whole body exposure to background radiation and the odd higher source like a medical x-ray maybe we can assume that the entire area of the skin is exposed to this amount on average, so we can find the average exposure of 1cm of skin as follows:

- Average body area 19000cm2
- Average year dose / cm area = 2.7mS / 19000cm2 = 0.142uS/cm2

Now compared to our Tritium bead exposed bit of skin:

Difference 438uS / 0.142uS = 3084 times the normal background for that bit of skin/muscle underneath.

Now to me this sounds like it could be of some concern. As for calculating what risk this would cause, I am not sure yet, but I am trying to find out.
The factors would be dependent on to what depth this radiation can penetrate, and how much energy the x-rays have.

Maybe this wouldn't be a problem if in the pocket only exposing skin and muscle tissue on the thigh, but if you have.. Big pockets, maybe the source might be sitting on the other side, with a direct line of sight to err your 'scintillation crystals' if you get what I'm saying. And I'm sure they wouldn't like being exposed to 3000 times the normal background rate of radiation.

The next thing I did was put the bead in the new peltier cloud chamber (Inspired by the one made by Justin Atkin's video) I have built, once again, the radiation visible is not insignificant: https://www.youtube.com/watch?v=FcxO6iL ... =BenHurren

Anyway I'll post more when I have some more scientific measurements, I would love to know your thoughts.

Ben

[gwgw]

I guess the biggest concern with tritium would be if you burn it to produce tritiated water, then drink or inhale the water vapor.

[Geoff]

Wait til he finds out about radon

[Rob Tayloe]

Tritium generally poses an internal hazard upon uptake rather than an external hazard. An exception is when T-T or D-T reactions occur in significant number in relatively close proximity. One such way of thinking about this is recalled by the old saying - "close only counts in horseshoes, hand grenades, and H-bombs".

Additional information can be found in the HPS fact sheet -
https://hps.org/documents/tritium_fact_sheet.pdf

One method of tritium production is as a byproduct from nuclear power plants. This report discusses hazards from such production -
https://www.nirs.org/wp-content/uploads ... report.pdf

Here are other reports and documents that discusses tritium hazards (one should take care to assess the credibility of internet information) -
http://www.ccnr.org/tritium_1.html
http://www.ccnr.org/tritium_Fairlie.pdf
https://www.ianfairlie.org/news/the-hazards-of-tritium/
https://www.nrc.gov/reading-rm/doc-coll ... on-fs.html
https://ehs.yale.edu/sites/default/file ... ope-h3.pdf

[kotarak]

One thing you could do is to check out the dozens of Youtube videos showing tritium vials inside a cloud chamber - I also have a video, I made of this, on my blog page (blog.kotarak.net).
It is not really quotative approach but rather visual. You'll see the amount of beta particles leaving the glass vial and how far they travel in air. Testing this way by placing layers of fabric around the vial (or acrylic tubing the case of the tritium keychains) will give you also idea if this provides any shielding.
In terms of detection efficiency, a cloud chamber should be much better than GM tube and more realistic as you can observe 4xPi environment and no side effects of attenuation by the GM tube envelope.
Overall, the tritium vials IMHO are not serious concern for exposure - you are getting way much more from environmental factors - (for example I have granite stones in my fireplace clocking at over 700 CPM ).
Running an electrostatic air-filter (Ionic Breeze) in my living room for 12 hours and then wiping the collection cell with alcohol swab and checking it with a Geiger counter peaked at 190CPM from Radon daughters - just putting the things in perspective.

[Ben H]

Also I'm not surprised that you get a lot of radon daughters in your air if your granite fireplace is that active!

[kotarak]

Also I'm not surprised that you get a lot of radon daughters in your air if your granite fireplace is that active!

Radon is quite common - basements and well waters. Most people living in the suburbs in US are on private wells so radon is really unavoidable.
I live in suburban Connecticut - not necessarily known for Uranium deposits. If I bring a Geiger in the bathroom and take a shower, the background jumps from 0.15 uSv/h to 0.22 uSv/h. For those, who live on the Colorado Plateau the Radon is even more present in the air and water.
A random granite boulder at the entrance of our local park clocks at 300 CPM.
If you have a smoke detector in your bedroom as recommended - you are getting at least 0.008 mRem annually from the weak gamma emitted by the Am-241 source.
I dont want to engage in Health Physics and advise on whether it is safe to have a tritium keyfob, pendant or tritium watch but I personally would not lose any sleep over potential exposure from these tritium vials.
Every time I fumble with the 1 uCi of Co-60 or 10 uCi of Cs-137 disk sources to calibrate my Gamma Spectrometer or carry on my shoulder a 40Lb bag of Potassium Chloride for my water softener or flying from New York to LA and back I am getting more exposure than from a puny tritium vial hanging from my car keys.

[gwgw]

Most of the radon produced from the granite block will never escape it and would remain trapped until it decays though. Another thing is it might actually contain thorium rather than uranium which decays to a different radon isotope that has much shorter half-life. E.g my floor and bathroom tiles and my kitchen countertop have relatively high activity but give a typical thorium spectrum. I live on the 3rd floor (4th counting the ground floor). Radon averages around 30 bq/m3 but sometimes it might suddenly shoot up to 80 in hours, depending on weather, atmospheric pressure, etc. It certainly comes from a source different than granite countertop, tiles, etc.

[kotarak]

Here is a government level research on the subject:

https://inis.iaea.org/collection/NCLCol ... 001618.pdf