PD Design’s relationship with Humboldt Bay began when Steve Larson conceived the Reactor Vessel Segmentation approach that was accepted by PG&E. This plan was unique in that the reactor was encased with asbestos and “windows” needed to be cut in the vessel to facilitate removal of the asbestos, prior to final segmentation of the vessel itself. The approach was then utilized to create the concepts for the design of the equipment necessary to complete the plan.
VMM – Vertical Milling Machine
The Vertical Milling Machine is a 14 foot tall Vertical Tower for cutting the vertical portion of the window in the Reactor Vessel. The VMM has a rotary saw blade acting as a milling cutter. The blade module is detachable (remotely) from the main frame of the VMM. This allows for a complete blade change without losing location of the machine, thus assuring that a partial cut can be resumed on the same cut line.
The VMM has the ability to carry two saw modules at the same time allowing for less setups of the VMM frame.
The frame of the VMM will mount inside the Reactor Pressure Vessel with hydraulic extension of the legs on the vessel opposite the cut line.
HMM – Horizontal Milling Machine
The Horizontal Milling Machine was designed and will be utilized to cut the Top and Bottom portions of the Windows. Because there are several horizontal cut lines required, the HMM required unique versatility allow mounting the saw blade at different elevations. The modular design of the HMM minimized the different components required.
The frame of the HMM fits through a bottle neck opening at the top of the RPV when the legs are retracted. The four clamping legs then extended independently (and remotely) to mount inside the vessel.
TMM – Tendon Milling Machine
The Tendon Milling Machine was designed to cut a section of Window tendon and retain it after cutting. The TMM utilized a cutting module similar to the Horizontal Milling Machine to perform the cut, while clamping onto the tendon during cutting.
The Tendon Milling Machine used the same cutting procedure as the HMM. Once the piece was cut, both the HMM and the tendon were lifted from the RPV.
RHC – Rigging Hole Cutter
The Rigging Hole Cutter was utilized to cut 1 or 2 holes in a given piece allowing for rigging the piece for removal. The RHC was designed to utilize the frame and part of the rotating table from the HMM for ease of alignment and modularity.
Blade Flush System
A Blade Flush System is offered to help increase cutting blade life. A common problem cutting stainless steel with this type of blade is the cutting debris (“chips”) remaining in the blade teeth. While not all the chips may be able to be removed, this feature will certainly help increase blade life. Pool water or other water will enter a water pump located above water level then exit via hose to the machine.
A failsafe height gauge is available. This would bolt onto the center of the Stationary Frame and be able to hold the weight of the machine in the event of a Clamp Leg failure. It would also assure that the machine was at the pre-set elevation on the gauge.
Debris Catch Pan
Attached to the bottom of the Stationary Frame could be a Debris Catch Pan. This will help collect the cutting debris during cutting. It is not meant to collect all the debris, but a large portion of it. When desired the debris may be vacuumed up and disposed of.