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STREAMLINING NUCLEAR POWER


Converting a nine-piece weldment to a single investment casting lowered the total cost of ownership for a nuclear fuel assembly component produced by Westinghouse Electric Co.


BY SHANNON WETZEL, SENIOR EDITOR T


he fuel assembly for a nuclear reactor produced by Westinghouse Electric Co., Cranberry Township, Pa., provides the power plant’s energy source. In the fuel assembly, the primary water flow is heated to approxi- mately 600F with the ultimate end goal of turning the turbine for electricity production. The assembly was functioning adequately in the company’s current reac- tors, but according to Mark Peterson, principal value engineer at Westinghouse, the design and purchasing team couldn’t help but think, “We can do this better.” The fuel assembly top nozzle constrains the loca-


tion of the fuel rods while channeling the water flow to the exit of the nuclear core. Originally, Westinghouse designed the nozzle as a nine-piece weldment made from plate and bar stock. It produced a few components internally and sourced the rest to an external supplier. When the company started to think about its next generation reactor, the AP1000® power plant, it focused on reducing its supply chain and value stream, making the nozzle a prime candidate for a casting conversion. Te AP1000 core consists of 157 14-ft. fuel assemblies with a removable top nozzle. “This effort came about while working on our next generation fuel proj-


ect,” said Michael Lewis, principal value engineer. “What could we do techni- cally to reduce the supply chain? Out of that we developed this campaign to change from a multiple piece weldment to a one-piece component while making sure we met all the requirements.” Westinghouse Electric partnered with its casting source, GSC Foundries,


Ogden, Utah, to finalize a casting design with optimal manufacturability and castability that also met the application’s requirements. “We have a very detailed concurrent engineering process,” said Steven


King, global director of supplier manufacturing and value engineering. “When we work with a supplier that has demonstrated good performance in the past, we integrate them into the development. It helped us with the cycle time of the development, and we have come up with a much better design.”


Turn-Key Supplier Te conversion to casting was a long


time coming for the nozzle part, ac- cording to King. Westinghouse Electric first entered the nuclear energy market in the 1950s and has been building fuel assemblies for commercial fuel reactors in its own manufacturing facility since 1969. Up until the 1990s, the company made all the components in-house, but through capacity planning, it moved most components, such as the fuel nozzle, to an external supply base. “We realized the cost of some com-


ponents as machined parts, forgings or weldments, was not cost-effective,” King said. “We started looking in the 1990s to go to a single-piece casting, but the technology was not available then.” Ten years ago, Westinghouse


started contracting with GSC Industries, which does precision investment casting for the automo- tive, aerospace and nuclear indus- tries. Over the course of the last decade, the nuclear energy company has been evolving its designs to take advantage of refined casting capa- bilities at GSC. In 2007, it revisited the possibility of designing the weldment nozzle as a casting. First, Westinghouse reduced


Jan/Feb 2013 | METAL CASTING DESIGN & PURCHASING | 21


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