UNCLASSIFIED
'
the source plane were measured with ionization-chamber dosimeters.
Analytical expressions of the buildup factor to account for the in-
crease in dose caused by scattered radiation wete developed, and
experimental results compared with theory.
The conclusions established were:
4
1. Buildup factors to account for ground-and air-scattered
radiation at a height, h, above an annulargource of slant radius, r, may
be expressed by B(h,r) = a+b ur + coe” c
y 48 follows:
Boo-69(h = 1 ft) = 1.09 + 0.549ur + 0.189e-T1- lyr
ar wi
serene!
ON re
Boo-60(h = 3 ft) = LLL + 0.529ur + 0.157e-86-1ur
Boo-60(h = 6 ft) = 1.13 + 0.529ur + 0.150e756-2ur
meer
Bos-137(h = 1 ft)= 1.03 + 0.629ur + 0, 16he-18- 3yr
Bos-137(h = 3 ft)= 1.04 + 0.68lur + 0.158e-13-1ur
Bos-137(h = 6 ft)= 1.07 + 0.677ur + 0.118e-10. Tyr
2. The dose rate at height, h, above a uniformly contaminated
disk of radius X may be determined by the expression above for the buildup
factor and the following equation: |
D(h,X) = D(h, R) = 2nDp
rs 4
a
[Ex
(uh) - {mn (uR)]
+ Co en {(e + 1)
where R@ = h® +
(un)}]
+d { e-(m)
~e7 (uR)
-[e {er + 1) (ur)
xé
3. For radii greater than approximately 7O feet, experimental
results agreed within + 5% with theoretical calculations of the gamma dose
rate above uniformly contaminated planes of cobalt-60 and cesium-137.
4.
The experimental dose rates aboveauniformly contaminated
robe ty
infinite plane are:
WNRC
UNCLASSIFIED
78
T>