T.O. 33B-1-1
6-154
Table 6-28. Peak Voltage (kVp)
TABLE. HALF-VALUE AND TENTH-VALUE LAYERS
|Approximate values obtained at high attenuation for the indicated peak voltage at, Peak Voltage (kVp)
Attenuation Material
Peak Voltage (kVp)
Lead (mm)
Concrete (in)
Steel (in)
HVL
TVL
HVL
TVL
HVL
TVL
50
0.05
0.16
0.17
0.6
70
0.15
0.5
0.33
1.1
100
0.24
0.8
0.6
2.0
125
0.27
0.9
0.8
2.6
150
0.29
0.95
0.88
2.9
200
0.48
1.6
1.0
3.3
250
0.9
3.0
1.1
3.7
300
1.4
4.6
123
4.1
400
2.2
7.3
1.3
4.3
500
3.6
11.9
1.4
4.6
1000
7.9
26
1.75
5.8
2000
12.7
42
2.5
8.3
3000
14.7
48.5
2.9
9.5
4000
16.5
54.8
3.6
12.0
1.08
3.6
6000
17.0
56.6
4.1
13.7
1.2
4.0
10000
16.5
55.0
4.6
15.3
Cesium-137
6.5
21.6
6.2
.064
2.1
Cobalt-60
12
40
8.1
0.82
2.7
Radium
16.6
55
2.7
9.2
0.88
2.9
6.9.20.1
Quality of Protective Material.
All shielding materials shall be of assured quality, uniformity and permanency
6.9.20.2
Lead Barriers.
a. Lead barriers shall be mounted in such a manner that they will not cold-flow because of their own
weight and shall be protected against mechanical damage.
b. Lead sheets at joints should be in contact with a lap of at least one-half inch, or twice the thickness of
the sheet, whichever is the greater.
c. Welded or burned lead seams are permissible provided the lead equivalent of the seams is not less than
the minimum requirement.
6.9.20.3
Joints Between Different Materials or Structures.
a. Joints between different kinds of protective materials shall be constructed so that the overall protection
of the barrier is not impaired.
b. Joints at the floor and ceiling shall be constructed so that the overall protection is not impaired.
