## Tuesday, September 24, 2013

### Physicsforums.com useful formulas

I was making up these formulas from scratch last week, actually easier to just find someone else's!   LOL

Great site, you have to register.   They have some smart moderators too (and I don't mean Boron, get it:-)).    However the moderators are "part of the system" meaning they are deeply involved in nuke and have an inherit conflict of interest.
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Hi Clancy688 - more or less the same question occurred to me - this is how I did it:

the Bq number gives you the activity of a quantity raqdioactive material where one nucleus decays per second and is tied into atomic mass and half life by following equation:

Bq = (m / ma) * Na * (ln(2) / t1/2)

m=mass in grams, ma = atomic mass, Na = avogadro constant, t1/2=half life in seconds

if you had Cs137 at 10,000TBq and half life is 30.17 yrs

then m= Bq / (Na * (ln(2) / t1/2)) * ma => m = 10E15 / (6.02E23 * (ln(2) / 9.51E8))

m = 0.166 grams
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