Westinghouse 3D printing trials reveal cost savings for all reactor types

New research has shown that additive manufacturing (AM) can halve manufacturing costs for replacement nuclear parts and complex design prototypes will demonstrate efficiency gains for advanced reactors, Clint Armstrong, Advanced Manufacturing Expert at Westinghouse, told Nuclear Energy Insider.

The U.S. Department of Energy awarded Westinghouse $8 million in July 2016 towards a five-year research and development program to advance innovative technologies. The research aims to improve the commercial viability of nuclear components manufactured through AM (3D printing) technology.

Tests have already shown binder jetting AM has cut manufacturing costs by up to 50% and lead times by up to 75% when used to produce casting molds for replacement motor parts on operational plants, Armstrong told Nuclear Energy Insider in an interview.

Research is also being carried out on laser powder bed AM to cut manufacturing costs and lead times for new and complex reactor designs used on SMRs and the next generation of advanced reactors, he said.

Other proponents of nuclear AM research include GE Hitachi Nuclear Energy, which is leading a $2 million project funded by the DoE to improve the efficiency of manufacturing replacement parts for operational plants.

In addition to its U.S. program, Westinghouse has partnered with the UK Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC) on studies to enhance SMR design efficiencies and cut build times.

Westinghouse is targeting its first SMR within a decade and the firm wants to “optimize manufacturability right from the start,” Mick Gornall, Westinghouse's Vice President and Managing Director for the UK and Middle East, said at the SMR UK Summit in October 2016.

The UK government has pledged least 30 million pounds ($36 million) towards SMR advanced manufacturing research and the Nuclear AMRC has developed partnerships with several major nuclear firms.

The research has shown investing in AM could cut build times for SMR reactor pressure vessels from around three years currently to less than six months, Udi Woy, Additive Technology Lead at Nuclear AMRC told Nuclear Energy Insider in September 2016.

“AM is an opportunity for new business models and we want it to be a contender with manufacturers bidding for SMR build work,” Woy said.

              UK additive manufacturing research funding by sector

Source: UK government's 'Mapping UK Research and Innovation in Additive manufacturing' report (February 2016).

Laser powder

Around $1 million of DoE funding will support the development of laser powder bed AM in producing metal components certified for use in nuclear plants. Led by the Electric Power Research Institute, the project began in October 2016 and will leverage emerging process analytics, in-situ computation models and big data mining to prove the validity of the qualification process.

This AM process stacks thin layers of powdered metal to the design of the part, while using a laser to fuse each new layer to the one beneath. Although the process has been shown to enhance the quality of complex nuclear components, it has not yet been given full regulatory approval for the production of critical or safety-related parts.

Westinghouse, together with Rolls Royce, will take the industry lead, with collaboration from Oak Ridge National Laboratories and the University of Tennessee. The aim is to improve the qualification process to standards accepted by the nuclear industry and approved by the Nuclear Regulatory Commission (NRC), Armstrong said.

Westinghouse is the first company to successfully irradiate and conduct post-irradiation tests on materials including 316L stainless steel and nickel alloy 718 used by laser powder bed AM to construct components. The company is also currently irradiating an AM produced zirconium alloy for use in its fuel division and a reactor-ready part is expected to be deployed in a commercial reactor by early 2018, subject to NRC approval.

Design flexibility is the main benefit of AM as it can produce parts with complex features and geometry, said Armstrong. The consolidation phase enables sub-components to be manufactured as one entity in a single production run, eliminating the need for welding or outsourcing of component machining and assembly.

“Laser powder bed AM enables new and complex designs for our SMRs and next generation of advanced reactors. The overall objective is to cut manufacturing costs and lead time, so we are working on developing and testing prototype components,” Armstrong said.

New prototypes

Binder jetting is a lower-cost AM technology that has the capacity to produce large components, said Armstrong. Westinghouse is studying the use of binder jetting technology to manufacture prototype components for its SMR and advanced reactor designs.

The binder jetting process lays down alternate layers of powder-based materials and uses a print head to dispense a liquid binder that glues the layers together. After each layer is deposited, the component is lowered onto a build platform and another layer of powder is screened on. The components are consolidated by sintering.

Binder jetting can produce large sand-casting molds, which could be used to cast more replacement parts for operational nuclear power plants including safety-related components.

Westinghouse has already shown binder jetting cuts costs and lead times and Armstrong said utilities could use the technology to shorten scheduled maintenance outages for priority repairs.

Binder jetting also has the advantage that it can be applied now from a regulatory standpoint.

“The real benefit is in using a digital process to create the casting mold, but the casting is by traditional methods and has a qualification for safety-related components so binder jetting AM can be applied now,” Armstrong said.

“Our next step is to identify those components that will deliver the best cost and lead-time benefits by being manufactured by binder-jetting, as well as the opportunities that can be exploited by expanding its application.”

By Karen Thomas