Description

Roll-on Shield Assembly consists of a mobile Roll-on Shield structure assembly and stationary Fixed Shield assembly. The Roll-on Shield structure assembly covers the hatch opening in the FM vault floor when it is in the fully advanced condition.

The Roll-on Shield structure assembly together with stationary Fixed Shield assembly provides the necessary Shielding over the hatch opening to reduce the radiation fields beneath the hatch opening. This facilitates access into the FM Service Area for maintenance of fueling machines and other auxiliary systems even when the reactor is operating. Rails are provided for movement of the shield, along with guide legs, front rollers, drive actuators and stopping and safety mechanisms

Construction details

• Material: SA 516 Gr 70
• Dimensions: 10m x 2m x 1 m - Box section filled with heavy concrete
• Total Weight: 90 Tonnes

Critical aspects

• Alignment of guide rails is critical for proper movement of the roll on shield on the rails
• Guide leg assembly has to be perpendicular to the rails
• Mating face of roll on shield must be perfectly flat to ensure that there are no gaps when the shield is fully closed, thus preventing leakage of radiation
• All these parameters were checked using an optical laser tracker