Dealing with tritium in the real world

[mmitchelmoss]

Hey gang,

I know, another tritium question. Please have mercy on me.

So I just purchased a Hamilton watch. It was supposedly made in 1972 and shows the T Swiss T label at 6 o'clock. I am therefore assuming it is a tritium watch. You can see the lume on the hands and little dots at each hour. I don't know what tritium tubes look like, but this seems to be painted on to me.

Health wise, I'm sure the best thing to do would be to never open it and just wear it. However, I really would like to try to service it. The crystal could probably stand to be replaced at some point too. So, I have read every post that I could find on the Internet about dealing with tritium (radium too while I was at it, just to try and get all the info I could). Basically, what I have come away with is that it is okay as long as you don't inhale or ingest the radioactive dust. The thing that I cannot find on the Internet is how do you do that in real life. So, I guess I am hoping for some pointers on steps to take to ensure that you don't inadvertently snort up some dust while you are working on the movement one inch from your face. Likewise, what steps do you take to make sure that the dreaded dust doesn't contaminate your workspace?

Again, I may just let it go and not worry about opening it. If I could find some practical techniques to mitigate the potential issues, then I would be tempted to go for it. I just don't want to dust all the food in my kitchen (my current workshop) with anything in addition to what Monsanto has already sprayed on there.

Thank you all for you patience with a newb question about a sensitive topic.

[RyMoeller]

Radium has a half life of around 1600 years and undergoes alpha decay.  Since the half-life is so long, the amount of radioactive material painted on the watch face is pretty much the same regardless of how long ago the watch was manufactured.  Alpha decay is quite dangerous but only especially so if the radioactive isotope is able to enter your body via ingestion or inhalation (alpha particles can generally be stopped with a shield as thin as a piece of paper).

Tritium is a bit different.  The half life of tritium is around 12-13 years and it undergoes beta decay.  While beta particles can pass through thicker shielding, the half life of tritium means that a watch produced in 1972 has much less radioactive material on it than when it was originally sold.

As a general rule I remove the dial and hands of radium/tritium watches while wearing nitrile gloves and place them in a secure location.  The gloves are then disposed of and I wash my hands. Not much more than that should be required when servicing older radium/tritium watches.  If you want to be extra careful you can purchase a dosimeter fairly cheaply to check for contamination of your workspace- I did just that and confirmed that I wasn't spreading radioactive material around.

[RyMoeller]

That all being said, I should point out that Radium is nothing to scoff at.  Radium poisoning can be lethal and will cause a world of health problems.  When dealing with radioactive materials an ounce of prevention is worth a pound of cure.  You really cannot do too much research on the subject.  

[Geo]

Here's another post worth reading.

 

[clockboy]

I would wear a mask and disposable gloves no matter what I read on the internet. 

[Spook]

Oddly enough this is one of my degree areas. Tritium is not really anything to be worried about. Doses to the extremities are minuscule even handling the bare vials. I get more of a dose picking up a Cs-137 calibration sample for a gamma spectrometer for a few moments than you would holding a watch face worth of vials for a year. Don't go eating them for fun or anything.

Radium on the other hand is not something to mess with. I've walked by old aircraft with radium dials and it's set off my dosimeter. For a clock or display piece as long as you don't open it there's little to worry about, but for something you want to wear I'd have someone that knows what they're doing, and has a properly calibrated instrument check it. Calculating actual dose rate is a bit more involved than putting it by a meter. Instruments are typically calculated against Cs-137 for dose rates which is at 662 KeV, Ra-226 is at 186 KeV so it's a lower energy gamma and any dose rates shown by the meter will be off by a good amount. Having it calculated by using a gamma spectrometer will get the true dose rate.

As for servicing watches with radium the biggest danger is contamination. If it flakes off onto surfaces or tools you have a hot particle sitting there and potentially getting on something else. I'd personally invest in geiger based meter with a pancake tube and after using gloves and putting plastic under work items check everything carefully for contamination.

If there's more than a few removed parts then storing them in a lead pig is the smart thing to do and try not to have a lot of radium items in an area without good ventilation as radon gas is part of the decay chain. Gloves, mask, and something to cover the work surface is a minimum.

Here's two calibration samples and the lead pig in the corner.

 

 

[mmitchelmoss]

Thanks for the replies everyone. So it sounds like while I am opening the watch, storing the dial and hands, and cleaning the case, that I should wear my gloves, particulate mask, and glasses. Then probably again when I reinsert the dial and hands. I'm also thinking that for those moments of messing with the dial and hands, I could probably move my operation to the back deck so that I don't risk scattered material in the kitchen.

Do you guys who own a meter find that the radioactivity (dust particularly) is limited to the hands, dial, and maybe inside of the crystal, or do you find that it actually is all over the movement as well?

Thanks again

[Spook]

The correct textbook answer is to treat everything as contaminated until proven otherwise. Radium based lume paint doesn't normally turn into a dust but it can flake off. It won't be in the air unless you do something to put it there such as using an air duster. A meter also is very unlikely to pick up dust in the air unless it lands on it. To test for particulates we use a filter sampler that pulls 1m^3 of air through a filter than we then check.

Here's a video I made that has a demonstration of a meter and the inverse square law.

Mazur PRM 9000

I've never dealt with radium in watches as I really have no clue how to work on a watch right now. My experience is with the radium lume on aircraft gauges.