Quantcast Outgassing Expectations
 

Click here to make tpub.com your Home Page

Page Title: Outgassing Expectations
Back | Up | Next

Click here for thousands of PDF manuals

Google


Web
www.tpub.com

Home

   
Information Categories
.... Administration
Advancement
Aerographer
Automotive
Aviation
Construction
Diving
Draftsman
Engineering
Electronics
Food and Cooking
Logistics
Math
Medical
Music
Nuclear Fundamentals
Photography
Religion
   
   

 

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Back
Figure 2. Idealized surface showing idealized mono-molecular layers of water vapor
Up
Design Considerations - index
Next
Bulk Contamination Modeling


DOE-HDBK-1132-99
per 100 square centimeters (dpm/100 cm2). Since only the outermost mono-
molecular layers are affected, and since these layers are easily removed by a
simple wiping, the mechanical efforts expended to perform decontamination on
such surfaces will, if any, be minimal.
When the concentration gradients have been relatively large and/or the
exposure times have been relatively long, the affected mono-molecular layers
will range down into the intermediately bound layers (i.e., the relatively tightly to
relatively loosely bound layers). Under such circumstances, the surface
contamination levels will range from relatively low to relatively high (i.e., from a
few hundred to a few thousand dpm/100 cm  2). Because the tritium has now
penetrated beyond those levels that would normally be easily removed,
mechanical efforts expended to decontaminate such surfaces will be more
difficult than those described above.
When the concentration gradients have been large and/or the exposure times
have been long, the affected mono-molecular layers will range all the way
down into the very tightly bound layers. The tritium will have penetrated down
into the actual surface of the material, itself; see " ulk Contamination
B
Modeling,"below. Under such circumstances, the surface contamination will
range from relatively high to very high levels (i.e., from a few tens of thousand
to several hundred thousand dpm/100 cm  2), and that mechanical efforts
expended to decontaminate such surfaces could be very difficult.
Outgassing Expectations . The phenomenon of outgassing is rarely a
problem under the first of the exposure situations described above (i.e.,
situations in which the concentration gradients have been small and/or the
exposure times have been short). However, when systems that have been
exposed to even small amounts of tritium for long-to-very-long periods of time
are suddenly introduced to room air, or any sudden change in its equilibrium
situation, Reactions (5) and (6), (5a) and (6a), (8), (9), and (9a) can be thought
of as springs, and the initial phenomenon of outgassing can be described as
damped harmonic motion. Under such circumstances, therefore, a relatively
large, initial " uff"of HTO will be released from the mono-molecular layers of
p
I-100


Privacy Statement - Press Release - Copyright Information. - Contact Us

Integrated Publishing, Inc.