Some high energy linear accelerator installations require a specially constructed steel door with neutron absorbing borated polyethylene and lead for gamma ray absorption. These very heavy doors (3000 to 15,000 lbs) are fabricated to meet the physicist shielding specification. Our doors are configured with brookfield industries, Inc. motorized door operators, special interlock switches and energy absorbing door stops. brookfield heavy duty hinges selected for the weight of the door are standard. Battery backup units that open the door when power fails are available as an option. a-fabco offers standard design units for new construction or can design custom doors for special shielding requirements and for retrofitting to existing openings.