0 20 40 60 80 100 120 140

.0002

.0003

.0004

.0005

.0007

.001

0007

.0005

.0004

- ៩០០០

.0002

160 180 200 220 240 260 280

ADJUSTED GROUND FLOOR WALL MASS THICKNESS, X' (psf)

CHART 4

SUPPLEMENT B (Part 5)

Examples for Chart 5, "Shielding Effects of Height" 1, 2

1. In upper stories of buildings, the ground contribution is decreased by the effect of height. For convenience, an area is calculated as if it were on the ground floor, and then adjusted by a height correction factor, H..

Example: Assume same data as in example 1a for chart 3, except the shelter area is located on the fifth floor of the building; i.e., the detector is about 55 feet above the ground. Then from chart 5, H.-0.48, and

Ground contribution=0.096X0.48=0.046

NOTE: The value 0.096 is from example la for chart 3, which is for a windowless building.

2. To correct for apertures, use table CF-1, page 44.

Example: Same data as for example 1 above, except Ap%=25% (floors are “thick”).

Ground contribution through apertures (detector above sill level)=0.39×0.48×0.25
X0.4=0.019

Ground contribution through apertures (detector below sill level)=0.39 0.48X0.25
X0.2 0.0094

NOTE: The value 0.39 is from example 1b for chart 3.

The values 0.4 and 0.2 are from table CF-1, page 44. To

obtain the total ground contribution, the contribution through solid portion of wall should be added to contribution through aperture. (See example 3 for chart 3, p. 36.)

1 Chart 5 follows.

2 See "Shielding Analysis Outline, Ground Contribution (Aboveground Areas)" (p. 27).

HEIGHT OF DETECTOR ABOVE CONTAMINATION, H (feet)

CHART 5

SUPPLEMENT B (Part 6)

Examples for Chart 6, "Reduction Factors for Apertures, Ground Floor” 1

1. On the ground floor of a multistory building surrounded on three sides by other buildings and with the remaining wall covered by windows, the reduction factor from ground contribution decreases as distance from the aperture increases.

Example: Length of aperture, L=50 ft.

Ground contribution (detector 20 ft. from aperture)=0.19+

Ground contribution (detector 60 ft. from aperture)=0.06

2. Buildings across the street provide some shielding. To account for this, use table CF-3, page 44. Example: Same data as for example 1 above, except there are commercial buildings across the street, which is 100 ft. wide.

Ground contribution (detector 20 ft. from aperture)=0.20X0.4 0.08
Ground contribution (detector 60 ft. from aperture)=0.06X0.4 0.024
NOTE: The value 0.4 (W, 100 ft.) is from table CF-3, page 44.

=

1 Chart 6 follows.

120

0

0

20 40 60 80

100

120

140

160

180

L-LENGTH OF APERTURE (FEET)