Patent Number: 
Section: claims

1. Machinery system to cut out an approximately 20 feet diameter and approximately 36 inches thick steel-reinforced concrete circular segment at the top of a dome structure of a reactor primary containment, the system comprising,two diametrically opposite, movable cutting heads with adjustable cutting depth to gradually remove the concrete and steel around a perimeter at a certain radius of the circular segment of a planned dome opening,each cutting head equipped with multiple cutters with three axis directional movement and capable of rotating about its vertical axis at a set RPM, of vertically moving at a set rate and to a set cutting depth, and of traveling horizontally at a set feed speed in a circular arc forward from a starting point and reversing in an offset path from an end point back to the starting point in a repetitious manner. 2. The machinery system of claim 1, further comprising,a cross over structure for supporting the movable cutting heads, the structure capable of being temporarily anchored to the containment dome structure,a stationary circular inner and outer drive gear attached to the said cross over structure, andan inner and outer drive screw respectively engaged to the said drive gears and mounted on the movable cutting heads. 3. The machinery structure of claim 2, further comprising a lateral position setting and locking device mounted on a vertical support plate for reverse travel position of the cutting heads.