RE: help on point source calculations

["Harmon, Terry O'Devah (ONF) " <onf@bechteljacobs.org>]

For a point source,  D(1)*R(1)^2 = D(2)*R(2)^2.  Therefore, R(2) =
[{D(1)*R(1)^2}/D(2)]^1/2 =  [(4.2 R/hr)* (2ft^2)/.1R/hr] = 12.96 ft
..
D(1) = initial exposure.  R(1) = Initial distance.  D(2) = second exposure.
R(2) = second distance.  ^ means raised to the power of.

For a Line source, D(1)*R(1) = D(2)*R(2).  Therefore, D(2 )=
{D(1)*R(1)}/R(2) = {(600(1)}/36 = 16.7 mR/hr.

Note: at distances from the line source that are more than 3 times the
length of the source,  use the point source formula.
Terry Harmon
Sr. Health Physics Tech
Kelly Scientific Resources
Phone: (865) 241-0289
Pager: (865) 417-1592
Email: onf@ <mailto:harmonto@ornl.gov> bechteljacobs.org


	-----Original Message-----
	From:	Lzjk@aol.com [SMTP:Lzjk@aol.com]
	Sent:	Monday, May 29, 2000 4:25 PM
	To:	Multiple recipients of list
	Subject:	help on point source calculations

	Can anyone show me how to do the following problems? or send me some
good 
	examples with equations. 

	If the Co-60 point source had a radiation intensity of 4.2 R/hr at
two feet, 
	the distance at which the exposure rate would be 100 mR/hr  is ? 

	What equation do I use and please give a example on how to do it.


	next question

	Calculate exopsure rate at 3' from a 11' long line source. The line
source is 
	reading an exposure rate of 600 mR/hr at 1 inch from the line.

	Thanks for any help I can get.
	
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