Last Modified 04/23/09 11:27 PM
SHEARS FOR THE NUCLEAR INDUSTRY
Vale Industries Inc.’s range of shears for the nuclear industry are based largely on our range of standard barshears that are used in steel mills across the world. The major difference is that these tools are modified for underwater use in the cooling pools located at nuclear power plants.
To avoid contamination of the cooling pool, water is used as the power transmission medium, in place of the more common petroleum based hydraulic fluid. In some steel mill applications a water/oil emulsion is used for fire resistance, however in the pool, even this can contaminate the cooling water. As a result pure water is used as the working fluid. Vale Industries also produces a power unit specifically designed for this application; namely the air over water power unit. For details “Click Here".
Oxidation Problems Associated With Water
There are two major problems associated with using water as the working fluid. First, the water by itself is not a very good lubricant. Second, if the tool is ever removed from the cooling pool, even for a short period of time, it will quickly oxidize, making it useless. Both of these problems are solved by producing all of the components that make up the shear from oxidation resistant materials. This of course does not apply to the oxidation resistant polymers. Some components are produced from stainless steel where plating of regular steel is not feasible. The various components are plated with different materials, depending on the function of the part. Chromium, Cadmium and Nickel are all used.
Vale’s range of nuclear shears come in three basic guises: Semi-Nuclear, Nuclear and Crusher shears.
The semi-nuclear Barshear is a fully plated shear capable of being removed from the cooling pool without the associated problems of oxidation. All components are plated and/or made from oxidation resistant materials. The shears are designed to use water as their primary power source to prevent contamination of the cooling pool in case of leaks. Any shear in Vale’s standard range can be produced as a semi-nuclear shear. "Click Here" for details of standard shears.
The fully-nuclear range of shears have all of the qualities of the semi-nuclear shears with the addition that the cast c frame used on all barshears is hand ground to remove all pits and crevices on the surface. This provides for decontamination of the shear on removal from the cooling pool.
Vale Industries also produces a Crusher shear for the nuclear industry. Specifically designed at a customer’s request, the tool is a twin ram shear and crusher. It is commonly used for fuel rod sleeve de-commissioning. The fuel rod sleeve is inserted into the shear and a section is sheared off. The other ram is then activated and the section is then crushed flat. This is done to provide less volume of space required for the scrap in the storage drums, and therefore less space required in the cooling pool for storage of irradiated scrap.