Re: Measuring N16 -Gamma dose surveys

[RADPROJECT@aol.com]

In a message dated 8/18/99 1:26:06 PM Eastern Daylight Time, 
David.S.Villicana@ucm.com writes:

<< Is there a dose rate instrument that will measure the dose given off by 
N16?
 
 David Villicana
 Dresden 
 ComEd
 Training >>

David:
Back in the 1970s, I conducted numerous environmental dose surveys at several 
operating BWR's using  10" diameter high pressure argon filled ionization 
chambers [HPIC]. HPIC instruments have been widely used to measure the 
incremental gamma dose either in close proximity [a hundred feet or so from a 
turbine building, or at distances of 800 to 1200 feet distant looking at 
direct and skyshine gamma dose. 

As part of the licensing of the proposed Pilgrim II plant in the mid 1970s, I 
recall being hoisted up in wire mesh cage by a crane with my HPIC to measure 
the dose rate in a grid pattern at various heights above the ground to derive 
an estimate of the total man-rem dose to workers constructing a second unit 
next to an operating BWR.

At Vermont Yankee, a series of dose rate measurements heading back from the 
turbine building on a line normal to the high pressure turbine and off to the 
side many hundreds of feet at various power levels was able to derive 
isopleths of dose rate. This data was needed to determine plant compliance 
with a Vermont State regulation on fenceline turbine dose [which was very 
difficult to meet since VY had the closest site boundary of any BWR in the 
US]. These surveys led to the design and installation of a turbine deck 
shield wall designed to reduce the direct N-16 dose at the site boundary. 
Post installation N-16 gamma dose measurements showed the shield wall had 
reduced fenceline dose to a level below that mandated by state regulations.

Stewart Farber, MS Public Health
Public Health Sciences
172 Old Orchard Way
Warren, VT 05674
802-496-3356
new e-mail: RadiumProj@cs.com

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html