During the last few years Marcrist have developed several specialist machines designed specifically for nuclear decommissioning projects.
Being the supplier of most of the worlds concrete scabbling equipment, Marcrist have supplied needle guns, piston scabblers and flail machines for the removal of concrete in contaminated areas.
Having studied the problem in depth, Marcrist felt there had to be better methods of carrying out the work in these hostile environments, which would not only be safer for the operators but would also ensure a precise amount of concrete would be removed, thus reducing the amount of contaminated material to be stored.
Being one of the main suppliers of both diamond machinery and consumables in Europe, Marcrist felt that a solution could be found by developing Remote Controllable machinery that would be capable of 'Shaving' a pre-determined amount of concrete from the structures by using diamonds.
One of the problems with the scabbling systems already used to carry out this work was that more material than was necessary had to be removed to eliminate any possibility of high spots (i.e. protruding aggregate) thus giving several times more secondary waste than was necessary to both be contained at source and later stored.
Using already proven technology and machinery, the task of producing a machine system that could be used remotely, to remove as little as 0.1mm up to 20mm in one pass was designed.
The remotely controlled and operated shaving head follows a guide rail system. The guide rail can be placed in any plane from the horizontal to the vertical, therefore allowing walls, floors and ceilings to be shaved.
The shaving head follows the contours of the surface to be removed and compensates for surface unevenness of up to 270mm over one metre. With the resulting smooth finish, ready for re-painting if necessary.
The guide rail system works on an x/z axis basis, clamps itself to any surface and can also be interfaced with all popular deployment systems.
A remote controlled, self propelled floor shaving unit is also under development, as well as a hand shaving system.
The heart of the system is Marcrists uniquely designed, and patented, interlocking surface shaving diamond blades. This system enables the blades to produce a completely smooth, finished surface.
Five completely different systems have so far been designed and commissioned. The systems work on the same principle, that being the use of Marcrists shaving blades, mounted on a special drum which rotates, the waste material being collected via a dust shroud, connected to a vacuum extraction system. There have been requirements for different width drums, 150mm, 250mm & 300mm and different deployment methods.
Each of the systems feature contour following, and the depth adjustment can be remotely set The quick change diamond shaving heads already in use are achieving a life of 1000 to 1500m² per drum before requiring changing.Compared to scabbling, the concrete waste production rates have proved to be 55% lower at the equivalent decontamination efficiency with the added bonus that the operators, and deployment equipment, do not have to suffer the vibration from the conventional scabbling tools.
Tests have also been carried out to prove that the waste products (concrete dust with possibly the remaining parts Hydraulic single drum system of a paint layer) combined with suitable additives, can be incorporated in a cement matrix with an additional volume reduction factor.