Results 1 to 14 of 14

Thread: watch collections and storage - some further considerations

  1. #1
    Super Moderator dave's Avatar
    Join Date
    Jul 2008
    Location
    Blighty
    Posts
    7,015

    Exclamation watch collections and storage - some further considerations


    radon emissions from radium-dial watches

    abstract:

    Preliminary research during the latter half of 2011 has indicated that significant and potentially hazardous radon concentrations can arise from radium-dial watches stored in the built environment. Radium (226Ra) decays via alpha-particle emission to radon (222Rn); in addition, mesothorium (228Ra) and radiothorium (228Th) were also used in such watches and decay to thoron (220Rn). In the main experiments conducted to date, a set of radium-dial watches representative of a small private collection, was placed in a controlled access room, of volume 67 m3, that is continuously ventilated to the external environment. Prior to placing the watches in the room, the radon level at the maximum ventilation rate was ca. 10 Bq/m3. This rose to ca. 190-230 Bq/m3 following the placing of the watches in the room, again under conditions of maximum ventilation. When the ventilation rate decreased to a ‘standby’ setting, the radon concentration increased rapidly to ca. 2-3 kBq/m3, then decreased rapidly to the lower concentration when the ventilation rate returned to maximum. Extrapolation of results of monitoring a single watch under zero-ventilation conditions indicates that the zero-ventilation equilibrium concentration in the room arising from the set of watches exceeds 5 kBq/m3 and Monte-Carlo simulation indicates this could exceed 10 kBq/m3, both of which are greatly in excess of the UK Action Levels. Observation of such levels is largely unreported in the literature and our preliminary conclusion is that whilst collectors might be aware of the radiation hazard that arises directly from the radioactive material content of such watches, they are probably not aware of the large radon (and thoron) hazard that can arise, particularly if the watches are kept in a poorly ventilated room in a private house.
    http://nectar.northampton.ac.uk/4725/


    radium dial watches, a potentially hazardous legacy?

    abstract:

    This study re-examines the risk to health from radium (226Ra) dial watches. Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 μSv h− 1 at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 μSv h− 1). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 μSv h− 1, to the pocket watches, with its cover open. Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 μSv h− 1), although the highest ambient dose equivalent rate noted was 20 μSv h− 1. A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 μCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 μSv h− 1). For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. This assumes exposure from the back of the watch which is generally around 60–67% of that from the front. The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. Radium (226Ra) decays to the radioactive gas radon (222Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 Bq m− 3. All watches were placed in a room with a RAD7 real-time radon detector. Radon concentration average was 259 9 Bq m− 3 over 16 h, compared to background average over 24 h of 1.02 Bq m− 3. Over 6 weeks highs of the order of 2000 Bq m− 3 were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m− 3 on several occasions. Estimates of the activity of 226Ra in the watches ranged from 0.063 to 1.063 μCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 μCi (0.46 to 32.38 kBq) for wrist watches. The risk from old watches containing radium appears to have been largely forgotten today. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced.
    https://www.sciencedirect.com/scienc...60412012000645


    after putting your geiger counters aside radon is another aspect of collecting for consideration.

  2. #2
    Senior Member river rat's Avatar
    Join Date
    Jan 2009
    Location
    Montana USA
    Posts
    2,892

    Default

    I guess sooner or later I will start glowing in the dark

  3. #3
    Super Moderator dave's Avatar
    Join Date
    Jul 2008
    Location
    Blighty
    Posts
    7,015

    Default

    Quote Originally Posted by river rat View Post
    I guess sooner or later I will start glowing in the dark
    no you won't glow Mike: radon is a colourless, odourless radioactive gas, hence the ventilation..

  4. #4

    Default

    I rely on Readybrek to glow in the dark on the way to school in the morning.

  5. #5
    Super Moderator dave's Avatar
    Join Date
    Jul 2008
    Location
    Blighty
    Posts
    7,015

    Default

    original, not chocolate, I presume; hope you do it with milk and don't get lumps..


    Last edited by dave; 11-14-2017 at 11:59. Reason: added image.

  6. #6
    Junior Member
    Join Date
    Feb 2016
    Posts
    19

    Default

    Quote Originally Posted by dave View Post
    original, not chocolate, I presume; hope you do it with milk and don't get lumps..


    Interesting topic.What happens if the watches are kept in a safe for instance? Radium mainly decays to alpha particles?some gamma-so mainly low energy. You would think they would be unlikely then to be able to exit a safe,though a potential risk perhaps on opening the safe door and inhalation? I'm just wondering if I'll shift my ATPs in particular to a well ventilated attic. Any thoughts,safe in a safe?

  7. #7

    Default

    My wife tells me to keep my glowing lumps in the safe.

  8. #8
    Senior Member DaveH's Avatar
    Join Date
    Mar 2007
    Location
    Northern California
    Posts
    3,088

    Default

    I knew an awful lot of old watchmakers. As my friend Dave used to say "Something's got ta kill ya".

    Ian: My lumps no longer sparkle, shame really....

  9. #9

    Default

    Does anyone have access to the full article? It sounds like they put a large number of pocket watches in a room along with wristwatches. I would be interested in knowing the readings from only a few wristwatches.

  10. #10
    Super Moderator dave's Avatar
    Join Date
    Jul 2008
    Location
    Blighty
    Posts
    7,015

    Default

    there appears to be very little information available about this online.

    there are words like preliminary, estimates, assumes and can that are used in the quoted articles.

    certain types of granite worktops/countertops are known to increase radon levels in the home.


    for those of you not in the know here is some info about ready brek -

    https://en.m.wikipedia.org/wiki/Ready_Brek

    it used the advertising slogan - central heating for kids and get up and glow.

    tv adverts from the 1970s and 1980s showed children walking to school with a radiant glow.
    Last edited by dave; 11-15-2017 at 04:38. Reason: grammar.

  11. #11
    Junior Member
    Join Date
    Mar 2015
    Posts
    17

    Default

    Already heard about this article, because of a warming about keeping some of french aircraft clocks at home (I love the Lip Type 14, Zenith Type B/20 and I had 3 of each before offering 3 of them...).

    I have full access to the article. Watches list and conclusion here :


  12. #12
    Senior Member DaveH's Avatar
    Join Date
    Mar 2007
    Location
    Northern California
    Posts
    3,088

    Default

    The most radiant watches ever made in my opinion are the pre war Mido Multiforts. The combination of radium and small crowded dials make them look like a nuclear reactor when viewed at night. They were a very expensive watch in their day.

  13. #13
    Member
    Join Date
    Jul 2014
    Location
    CZ
    Posts
    70

    Default

    In the Grand scheme of things...when I left the Military my fitness dropped like a whore's drawers, I used to smoke 40 a day, I had a heart attack last year. And whilst recently I have had this well weird and highly unusually preference for salads at work every day... I normally love my red meat and cheese/ham rolls chocolate the odd pizza every now and then etc. etc. etc....if I die from my watches at least I've had a fair old amount of pleasure from collecting them.

  14. #14
    Junior Member
    Join Date
    Sep 2015
    Posts
    11

    Default

    I have read the article. Quite disconcerting. Email me at jamie at tenplusone dot ca if you would like a copy.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •