Stay Time Calculation - Panasonic PT-DZ12000U Operating Instructions Manual

Photon Shielding Buildup Factors
MeV Water
0.5 2.52
1.0 2.13
2.0 1.83
Neutron and Gamma Shielding
SIMPLIFIED SHIELD THICKNESS CALCULATION
perform radiation measurements to verify these calculations
I = shielded exposure rate
I = unshielded exposure rate
0
n = number of shielding layers (tenth or half)
I = I x 0.1
0
I = I x 0.5
0
Consider the potential for radiation streaming thru gaps in the
shielding. Design the shielding to minimize gaps and perform
a comprehensive survey after the shielding is in place.
Stay-time calculations are typically used to determine how
long an individual can remain in an area with elevated
radiation fieldsu ntil they reach some pre-determined dose
limit. The principles can also be applied to airborne areas.
Stay-time = Allowable exposure/exposure rate
example;
Stay-time = 100 mR / 25 mR/hr = 4 hours
Aluminum
2.37
2.02
1.75
n
for tenth value thickness
n
for half value thickness
Radiation Streaming
Stay-Time Calculation
allowable exposure is 100 mR
exposure rate is 25 mR/hr
Concrete
2.19
1.94
1.75
54
Iron Lead
1.98 1.24
1.87 1.37
1.76 1.39