PROJECT SCOPE
The project called for segmenting the RPV into seven sections ranging in height and weight from 4’ 10” @ 89,000 lbs. per segment to 7 @111,000 lbs. per segment respectively.

The Reactor Pressure Vessel, (RPV), had an inside diameter of 18’ 3”, Wall Thickness of 6.5" and was additionally clad with a 7/32” thickness of 308 Stainless Steel, bringing the total wall thickness to nearly 6.70”.

THE WTS SOLUTION
WTS and the E.H. Wachs Co. designed and built a custom hydraulic powered "RPV Segmentation Machine” specifically for this project. Use of the RPV machine was specified due to the combined advantages offered in terms of cutting speed, and to minimize the spread of particulate contamination. These factors serve to address ALARA requirements, yielding an estimated radiation exposure level of only 2-5 millirem per man hour for this project.

Assembled and tested by WTS personnel in our Wheeling, IL manufacturing facility the RPV machine frame has an outside diameter of 17' and, weighed approximately 8,000 lbs. Two starwheel activated, variable feed tool slides were mounted to the main frame and driven by a unique chain drive system.

The RPV machine, work platform and supporting structure, weighing approximately 23,000 lbs., was lowered into the RPV for each cut using the plants polar crane.

The RPV machine was then secured to the RPV inner wall with eight self contained, hydraulically actuated clamping legs. As machine rotation begins and tool slide starwheel trips are engaged, the tool slides begin to feed, progressing further through the RPV wall with each machine revolution until the cut was completed.

To prevent tool binding during the cutting operation, Six "U” shaped lugs, were bolted together and welded to the outer wall of the vessel, spanning the cut line to hold the sections in position.

In addition to the RPV machine, WTS personnel designed and built five custom hydraulic drills specifically for this project. These are used to bore 6” diameter holes for rigging in each of three vessel sections.

Upon completion of each cut, the RPV machine was lifted out of the vessel and the "U" shaped lugs were either torched apart or unbolted.

As each vessel segment was lifted off, it was transferred to a dry cutting station where it was further cut into either three or four segments using an Oxy-Fuel track mounted torch system to facilitate transport.