Document ajMN0dKMJ4jQGRMd1K5D7yp9

Ionizing Radiation CONSTRUCTION SPECIFICATIONS FOR INDUSTRIAL X-RAY OR GAMMA ENCLOSURES 1 All X-ray or gamma enclosures to be provided with protective barriers of sheet lead or equivalent protective materials of assured quality, uni formity and permanency 2 Sheet lead to be mounted so as to avoid cold-flow and to be protected from mechanical damage Sheet lead less than 1/16 in thick to be bonded to rigid supporting materials 3 Sheet lead joints to be overlapped with a lap at least 1/2 m , or twice the thickness of the sheet, which ever is greater Joined sheets to be m direct contact Butt joints may be used provided the welded or burned seams are not less than the minimum lead equivalent required 4 Joints between different kinds of protective materials to be designed to avoid leakage through the lighter material Where floor (or ceiling) is not lead-lined, lead sheet on wall to extend into floor (or ceiling) Joints may be flanged to provide, at the joint, protection equivalent to lead-lined walls 5 Comer construction to provide same protection as that required for body of enclosure 6 Lead sheets not to be perforated by nails, bolts or other fasteners unless they are adquately covered to give protection equivalent to unperforated lead sheet 7 Openings in barrier for pipes, conduits, air ducts, louvers, etc , to be pro vided with baffles so that transmitted radiation does not exceed that trans mitted by the barrier itself 8 Observation windows and doors to have the same lead equivalent as that required of surrounding wall 9 Where floor is not lead lined, door sill to be provided with lead baffle, lead covenng of door to overlap door jamb Radiation scattered under door or passing through door clearance spaces, not to exceed that trans mitted by door Fig 44-10 lfications are enumerated in Fig 44-10 Special attention must be given to the de sign of the joints between different protective materials, such as lead and concrete, in order to avoid leakage due to scattering through the lighter matenal This is illustrated in Fig 44-11 Where the control room, office space or film processing room is located adjacent to the shielded enclosure and ready access from 1464