Gilson and Voss - Voss Associates
Gilson and Voss - Voss Associates
Gilson and Voss - Voss Associates
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CALCULATING NEUTRON SHIELD THICKNESSES<br />
I = I0e -óNx<br />
where; I = final neutron flux rate<br />
I<br />
0<br />
= initial neutron flux rate<br />
ó = shield cross section in square centimeters<br />
3<br />
N = number of atoms per cm in the shield<br />
x = shield thickness in centimeters<br />
CALCULATING GAMMA SHIELD THICKNESSES<br />
"Good Geometry" (narrow beam) I = I0e -ìx<br />
I = shielded exposure rate<br />
I<br />
0<br />
= unshielded exposure rate<br />
ì = linear attenuation coefficient<br />
x = shield thickness<br />
-ìx -ìenx<br />
"Poor Geometry" (broad beam) I = B x I0e OR Ie<br />
0<br />
B = buildup factor<br />
ìen = linear energy absorption coefficient<br />
Half-Value Layer (HVL) = ln 2 / ì<br />
Tenth-Value Layer (TVL) = ln 10 / ì<br />
Transmission Factor (F) = I / I OR F = e -ìx<br />
CALCULATING TRANSMISSION FACTOR (F)<br />
FOR SHIELDING AN X-RAY DEVICE<br />
F =<br />
2<br />
Pd / WUT (BCF)<br />
P = permissible dose rate (mrem/wk)<br />
d = distance to point of interest<br />
W = workload (mA-min / wk)<br />
U = use factor<br />
T = occupancy factor<br />
BCF =<br />
2<br />
beam conversion factor (R / mA-m )<br />
0<br />
CALCULATING NEUTRON SHIELD THICKNESSES<br />
I = I0e -óNx<br />
where; I = final neutron flux rate<br />
I<br />
0<br />
= initial neutron flux rate<br />
ó = shield cross section in square centimeters<br />
3<br />
N = number of atoms per cm in the shield<br />
x = shield thickness in centimeters<br />
CALCULATING GAMMA SHIELD THICKNESSES<br />
"Good Geometry" (narrow beam) I = I0e -ìx<br />
I = shielded exposure rate<br />
I<br />
0<br />
= unshielded exposure rate<br />
ì = linear attenuation coefficient<br />
x = shield thickness<br />
-ìx -ìenx<br />
"Poor Geometry" (broad beam) I = B x I0e OR Ie<br />
0<br />
B = buildup factor<br />
ìen = linear energy absorption coefficient<br />
Half-Value Layer (HVL) = ln 2 / ì<br />
Tenth-Value Layer (TVL) = ln 10 / ì<br />
Transmission Factor (F) = I / I OR F = e -ìx<br />
CALCULATING TRANSMISSION FACTOR (F)<br />
FOR SHIELDING AN X-RAY DEVICE<br />
F =<br />
2<br />
Pd / WUT (BCF)<br />
P = permissible dose rate (mrem/wk)<br />
d = distance to point of interest<br />
W = workload (mA-min / wk)<br />
U = use factor<br />
T = occupancy factor<br />
BCF =<br />
2<br />
beam conversion factor (R / mA-m )<br />
0<br />
Page 56<br />
Page 56<br />
CALCULATING NEUTRON SHIELD THICKNESSES<br />
I = I0e -óNx<br />
where; I = final neutron flux rate<br />
I<br />
0<br />
= initial neutron flux rate<br />
ó = shield cross section in square centimeters<br />
3<br />
N = number of atoms per cm in the shield<br />
x = shield thickness in centimeters<br />
CALCULATING GAMMA SHIELD THICKNESSES<br />
"Good Geometry" (narrow beam) I = I0e -ìx<br />
I = shielded exposure rate<br />
I<br />
0<br />
= unshielded exposure rate<br />
ì = linear attenuation coefficient<br />
x = shield thickness<br />
-ìx -ìenx<br />
"Poor Geometry" (broad beam) I = B x I0e OR Ie<br />
0<br />
B = buildup factor<br />
ìen = linear energy absorption coefficient<br />
Half-Value Layer (HVL) = ln 2 / ì<br />
Tenth-Value Layer (TVL) = ln 10 / ì<br />
Transmission Factor (F) = I / I OR F = e -ìx<br />
CALCULATING TRANSMISSION FACTOR (F)<br />
FOR SHIELDING AN X-RAY DEVICE<br />
F =<br />
2<br />
Pd / WUT (BCF)<br />
P = permissible dose rate (mrem/wk)<br />
d = distance to point of interest<br />
W = workload (mA-min / wk)<br />
U = use factor<br />
T = occupancy factor<br />
BCF =<br />
2<br />
beam conversion factor (R / mA-m )<br />
0<br />
CALCULATING NEUTRON SHIELD THICKNESSES<br />
I = I0e -óNx<br />
where; I = final neutron flux rate<br />
I<br />
0<br />
= initial neutron flux rate<br />
ó = shield cross section in square centimeters<br />
3<br />
N = number of atoms per cm in the shield<br />
x = shield thickness in centimeters<br />
CALCULATING GAMMA SHIELD THICKNESSES<br />
"Good Geometry" (narrow beam) I = I0e -ìx<br />
I = shielded exposure rate<br />
I<br />
0<br />
= unshielded exposure rate<br />
ì = linear attenuation coefficient<br />
x = shield thickness<br />
-ìx -ìenx<br />
"Poor Geometry" (broad beam) I = B x I0e OR Ie<br />
0<br />
B = buildup factor<br />
ìen = linear energy absorption coefficient<br />
Half-Value Layer (HVL) = ln 2 / ì<br />
Tenth-Value Layer (TVL) = ln 10 / ì<br />
Transmission Factor (F) = I / I OR F = e -ìx<br />
CALCULATING TRANSMISSION FACTOR (F)<br />
FOR SHIELDING AN X-RAY DEVICE<br />
F =<br />
2<br />
Pd / WUT (BCF)<br />
P = permissible dose rate (mrem/wk)<br />
d = distance to point of interest<br />
W = workload (mA-min / wk)<br />
U = use factor<br />
T = occupancy factor<br />
BCF =<br />
2<br />
beam conversion factor (R / mA-m )<br />
0<br />
Page 56<br />
Page 56