Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: philthewineguy on 14/04/2021 19:20:04

Title: How do I calculate radioactive dose rate at a distance?
Post by: philthewineguy on 14/04/2021 19:20:04

If the dose rate from a sample of Tc-99 was 8.5 x 10 to the power of minus five mSv per hour at 1.6 metres, what would the dose rate be at 4.8 metres?

Title: Re: How do I calculate radioactive dose rate at a distance?
Post by: Bored chemist on 14/04/2021 19:49:40

What do you think it might be?

Title: Re: How do I calculate radioactive dose rate at a distance?
Post by: philthewineguy on 14/04/2021 19:56:53

Im thinking possibly 9.4 x 10 to the power of minus 6 but could be totally wrong

Title: Re: How do I calculate radioactive dose rate at a distance?
Post by: Bored chemist on 14/04/2021 22:49:26

Looks right to me.
I presume that you could, if required, show your working.

Title: Re: How do I calculate radioactive dose rate at a distance?
Post by: alancalverd on 14/04/2021 23:11:46

That's correct for a point source.

If the source is distributed over a significant area of radius r (such as contamination of a working surface or distribution in a human body) the dose rate at distance d  is independent of d at close range (d<r) , decreasing as roughly 1/d if d < 5r and tending to 1/d² if d > 10r.

But you didn't come here for the obvious answer, did you?