Page 307 - Radiation Safety

PROTECTION AGAINST EXTERNAL HAZARDS

(SHIELDING)

2. HVL for Cs-137 is 6.5 mm of lead. What is

the thickness of lead needed to reduce the

-1
-1
dose rate from 40 mR.hr to 2.5 mR.hr ?

I = I .e - 0.693x/HVL

o
x

I / I = 2 n
o
n

33