Siemens’ 3D printed replacement impeller (R) with its 3D printed prototype and the original impeller (L). [Image: Siemens]

Earlier this year, Siemens made history when it successfully completed the first installation and continuing safe operation of a 3D printed part inside a nuclear power plant. The part was a replacement impeller for a fire protection pump that provides pressure for the power plant’s fire protection system. Now power company Westinghouse plans to be the first company to install a 3D printed fuel component in a commercial nuclear reactor.

Westinghouse is looking to lower the cost of replacement parts as well as to speed the qualification of 3D printed materials. The company has been using additive manufacturing for casting molds to produce large replacement brackets and bearing housings for electric motors, and now it plans to use the technology to directly manufacture parts, or at least one part to begin with. By fall of 2018, Westinghouse plans to install a thimble plugging device made of 3D printed 316L stainless steel as well as non-3D printed 304 stainless steel, as Nuclear Energy Insider reports.

Over the course of the next year, Westinghouse is planning to explore how to reduce costs and lead times for obsolete and difficult-to-source parts, along with fuel structural components and prototypes for next-generation plants, such as impellers and microchannel heat exchangers. Additive manufacturing is a high priority for the company, which also plans to use the technology for other uses such as robotics, sensors, models for manufacturability and tooling.

In 2016, the US Department of Energy granted Westinghouse $8 million for multiple R&D projects focused on the advancement of new technologies, including a project working on qualifying powder bed fusion additive manufacturing processes for nuclear components. In July of this year, the DoE granted the company an additional $830,000 in federal funding to study the neutron radiation effects on zirconium alloys produced through additive manufacturing for light water reactors. The researchers will conduct post-irradiation examination of zirconium material that was irradiated at the MIT reactor.

Westinghouse is currently looking at three primary 3D printing technologies. Laser powder bed fusion is good for the production of small, complex fuel structural components, prototype components and tooling.  Directed energy distribution can be used to add features such as nozzles, bosses or flanges to existing components, and can reduce cost and lead time when used for weld repair or automatic cladding, as well as to produce larger or more complex components. Binder jetting can produce smaller, complex components for a lower cost than powder bed fusion. Westinghouse is also investigating friction stir, ultrasonic and metal spray processes.

In January of this year, Westinghouse estimated that additive manufacturing could cut the manufacturing cost of replacement parts by half.

“These cost and lead time reduction estimates still look appropriate for certain replacement castings, using current cost estimates for AM casting moulds and the associated foundries/casting processes,” said Clint Armstrong, Advanced Manufacturing Expert at Westinghouse.

[Image: Westinghouse]

The company has already cut costs by using 3D printing for tooling – in one case, the Westinghouse Specialty Metals Plant combined five parts into one part, using a metal that improved wear resistance and increased tooling lifespans.

One of the main goals now is to expand the framework of accepted standards as well as the pool of material performance data, including irradiation performance data.

“The main challenge in qualifying AM materials is the variability of material properties and overall part quality based on the feedstock material, AM process parameters and part geometry,” Armstrong said. “To combat this, most users are printing multiple parts for destructive testing, as well as multiple test specimens with production parts.”

This, unfortunately, can increase the cost of getting a 3D printed part to commercial production. Westinghouse is now collaborating with several other organizations on a DoE-funded project aimed at, according to Armstrong, developing an “in-process monitoring and integrated computational materials engineering process” to reduce the qualification process for additive manufacturing.

In addition, Westinghouse has participated on several ASTM F42 subcommittees on additive manufacturing, and is part of multiple America Makes & American National Standards Institute (ANSI) Additive Manufacturing Standardization Collaborative (AMSC) working groups. Recently, officials from the US Nuclear Regulatory Commission (NRC) met with proponents of additive manufacturing in nuclear power, and a two-day workshop in Washington, D.C. is planned for the end of the month.

“There are multiple people working on this in the nuclear industry, so there is momentum…We are all working together,” said Armstrong. “Getting all codes and standards in place is a lot of work.”

Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below. 

[Source: Nuclear Energy Insider]

 

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