Figure 16. Typical baffle design for openings in secondary barriers.
airflow and must extend far enough beyond the perimeter of the opening to provide the required degree of protection. See
figure 17 for details.
(2) Service boxes, conduits, etc., imbedded in concrete barriers may require lead shielding to compensate for
the displaced concrete. Where supplementary lead shielding is required, its thickness should be at least equal to the lead
equivalence of the displaced concrete. Conduits of 2 inches outside diameter (O.D.) or less do not usually require
additional shielding. The shielding should cover not only the back of the service boxes, but also the sides, or extend
sufficiently to offer equivalent protection. Conduits passing through the barrier should have sufficient bends to reduce the
radiation to the required level. See figure 18 for details.
During construction, a periodic visual inspection of the installation of lead-lined materials is recommended.
Specific observable points would be at joints, corners, and the overlapping of the lead. Voids in the shielding barriers must
be removed in the early stages of construction while they are still visible.