Quantcast Example 4.5. Potential Technology Shortfall for Breathing Zone Air Sampling of High Specific

 

Click here to make tpub.com your Home Page

Page Title: Example 4.5. Potential Technology Shortfall for Breathing Zone Air Sampling of High Specific
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
Example 4.4. Improving Detection Capabilities of Air Sampling Using Averaging
Up
Internal Dosimetry - index
Next
Example 4.6. The Number of Particles for Breathing Zone Air Sampling of a Lower Specific


DOE-STD-1121-98
Example 4.5. Potential Technology Shortfall for Breathing Zone Air Sampling of High Specific
Activity Alpha Emitting Nuclides
For high specific activity alpha emitters, a single large particle on an air sampler filter may
give erroneous results, a phenomenon that can be described as the "countable number of particles
problem." In facilities where 238Pu is processed, it may be difficult to use BZ or personal air
monitoring to control intakes near the level of 2% of a NALI. Using the methods in ICRP Publication
66, and a density of 11 g/cm3 for plutonium oxide (ICRP 1994a and p. 1.7 of Faust et al. 1988), the
table below was calculated. The equivalent physical diameter also accounts for slip correction and
thermodynamic effects, both important at small particle sizes. The table shows that one particle with
an aerodynamic diameter of 5 :m is approximately 2% of a NALI.
With Monte Carlo analysis, Scott et al. (1997) show that calculated average intake of high specific
activity alpha emitters, in DAC-h, is not an operationally useful quantity. They used a light activity
breathing rate of 1.5 m3h-1, a density of 10.0 g cm-3, an AMAD of 5:m, and a GSD of 2.5 and
calculated the intakes of 10,000 workers exposed. In an 8 DAC-h exposure, 9,831 had no intake, 4
had intakes greater than one ALI (that is, 2,000 DAC-h or 600 Bq of 238Pu), and 165 had intakes
ranging from a fraction of a DAC-h to nearly 2,000. All intakes resulted from inhaling a single
particle of 239PuO2. Thus, the average intake computed for the group of workers, would both
overestimate the intakes of the vast majority of individuals and seriously underestimate intakes of the
more highly exposed individuals.
Aerodynamic Equivalent
Number of Number of
physical Volume  Mass per Activity per particles per particles per
diameter
(:m)  dia. (:m)
(cm3) particle (g) particle (Bq)
NALI  0.02 NALI
0.1
1.2E-02 8.1E-19
8.9E-18
5.0E-06
1.5E+08
2.9E+06
0.2
2.9E-02 1.2E-17
1.3E-16
7.5E-05
9.6E+06
192,551
0.3
5.0E-02 6.7E-17
7.3E-16
4.1E-04
1.8E+06
35,224
0.5
1.0E-01 5.6E-16
6.2E-15
3.5E-03
207,805
4,156
0.7
1.6E-01 2.1E-15
2.4E-14
1.3E-02
54,698
1,094
1
2.5E-01 8.1E-15
8.9E-14
5.0E-02
14,530
291
2
5.5E-01 8.6E-14
9.5E-13
5.3E-01
1,361
27
3
8.5E-01 3.2E-13
3.5E-12
2.0E+00
367
7.3
5  1.4E+00 1.6E-12
1.8E-11
9.8E+00
74
1.5
7  2.1E+00 4.5E-12
5.0E-11
2.8E+01
26
0.52
10  3.0E+00 1.4E-11
1.5E-10
8.3E+01
8.7
0.17
20  6.0E+00 1.1E-10
1.2E-09
6.8E+02
1.05
0.021
30  9.0E+00 3.8E-10
4.2E-09
2.3E+03
0.31
0.0062
50  1.5E+01 1.8E-09
2.0E-08
1.1E+04
0.066
0.0013
70  2.1E+01 4.9E-09
5.4E-08
3.0E+04
0.024
0.00048
100  3.0E+01 1.4E-08
1.6E-07
8.8E+04
0.0082
0.00016
200  6.0E+01 1.1E-07
1.3E-06
7.0E+05
0.0010
0.00002
300  9.0E+01 3.9E-07
4.3E-06
2.4E+06
0.00030
6.1E-06
42


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

Integrated Publishing, Inc.