radioactive clocks???

[caracasjim]

Whatever happened to all those luminous clock faces we used to have back in the 60's and 70's.??? Do you think Al Qaeda has them all???How many of them would it take to make a dirty bomb???

[ike_kozik]

Hi, it's probably very unlikely they could:

1. luminous paint in clocks usually contains radium which would need to actually be ingested in large amounts.

2. even if clocks contained more radioactive elements such as Plutonium or Uranium, they would need to be of a certain isotope and either Plutonium-239 or Uranium-235.

3. the critical mass for a true WMD is something like 11kg for Plutonium and 56kg for Uranium, given radioactive decay in the luminuos paint, perhaps with only 0.0000001g of active component even to construct a 11kg weapon would require about 1100 million clocks - this makes me feel better.

http://www.fas.org/nuke/intro/nuke/design.htm

ceasium or cobalt could be used in a dirty bomb, although the human body could probaby handle elevated levels of this kind of radioation depending on the amount contained in a device.

http://science.howstuffworks.com/dirty-bomb3.htm

I'm going to make myself feel happier, by thinking they would either need every clock on the planet and probably some more, or that they would need to feed us lots of radium.

[Tim B]

Any thoughts on Strontium 90?

[caracasjim]

I like what the manufacturer writes:

In the old days workers who would use their mouths to point up the brushes to paint luminous material on aviation indicators and clocks ended up with tongue, throat, and lip cancer.   We are not aware of any recorded health hazard with these dials installed on the clock in normal use.   Remember, however, that the half life on the old radium paint is in the many hundreds of years.  It is advisable to avoid scraping it off the hands and touching it. The phosphorescent material dies off, but the radium remains alive and well for a long time

[jenstar]

If you had enough atomic clocks, could you make a time bomb?