It operated for several years but developed primary system leaks that could not be repaired, and was therefore no longer economic to operate. It was a 17 MWe BWR designed and built under the Atomic Energy Commission (forerunner of the current US DOE and US NRC) Demonstration Reactor Program. The earliest application of underwater segmentation of reactor vessel internals was at the Elk River Reactor (ERR) in Minnesota. The technologies developed include plasma arc cutting, high-pressure abrasive water jet cutting, mechanical cutting, and metal disintegration machining. LaGuardia, in Nuclear Decommissioning, 2012 19.3.1 Application of underwater segmentation technologiesĪs noted earlier, the relatively high dose rates associated with reactor vessel internals necessitated the development of remotely operated segmentation methods to safely size-reduce the internal components.
However, it is the fastest cutting method. PAC results in dose issues related to debris control and water clarity problems. When cutting complex structures within reactor internals, supporting devices are required to handle the tool and the cut pieces.īased on the comparison summarized in Table 7.1, we can conclude that: Such a system can be simple to use because the plasma process (once started and not working at its physical limits) is quite insensitive to the distance between torch and workpiece, as well as to a constant cutting speed. A thickness of 20 mm was successfully cut in water at a depth of 20 m ( Steiner and Priesmeyer, 2003).Įquipment for remote-controlled handling of an underwater plasma torch (which moves along a planned cutting line) is commercially available. This process is not only capable of cutting thin sheet structures such as steam- and water-separators but also other internals, up to a material thickness of 130 mm ( Pfeifer et al., 2004).
In addition, underwater segmenting of the highly activated internals of a reactor pressure vessel has been undertaken by plasma arc cutting in several decommissioning projects.
Cut 40 plasma cutter circuit diagram manual#
Manual cutting with plasma arc of a water loop line out of 40 mm stainless steel. The material thickness to be cut has a physical limit of about 180 mm, depending on the possible length of an electric arc, which, in turn, depends on the output voltage of the power source used.ġ2.4. Because this process is an electric circuit, its field of application is limited to metals. Cutting is also possible under water but performance decreases with increasing water depth. Moving the torch creates a kerf with a clean cutting edge. The plasma gas exits the torch through a nozzle as a jet with high kinetic energy and capable of melting not only every metal, but also blowing away the molten material.
A gas (such as argon, nitrogen, hydrogen or air) is injected into the arc inside the torch, turning it into a plasma with a temperature of more than 10 000 ☌. This process is based on an electrical arc between an electrode inside a torch and the workpiece. Steiner, in Nuclear Decommissioning, 2012 12.2.4 Plasma arc cuttingĪnother very common thermal cutting technique is plasma arc cutting.
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