ORNL achieves nuclear industry first with additively manufactured rabbit capsule for test reactor
January 21, 2025

A research team from the Department of Energy’s Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee, USA, has designed, manufactured, and successfully tested a specimen capsule for use in a High Flux Isotope Reactor (HFIR). Specimen capsules, commonly referred to as rabbit capsules, are used in nuclear fuels and materials research to hold experiments undergoing irradiation in a test reactor. The achievement is said to be a first for Additive Manufacturing.
To demonstrate that Additive Manufacturing could produce and qualify a rabbit capsule for use in a reactor, ORNL used a Laser Beam Powder Bed Fusion (PBF-LB) AM machine to build a stainless-steel capsule that was then assembled, loaded, and sealed.
The capsule was later inserted into HFIR for nearly a month, where it successfully weathered the effects of the reactor’s high neutron flux environment.
“This is a significant step toward demonstrating that Additive Manufacturing can be used to develop and qualify specialised components that cannot be conventionally machined,” said Richard Howard, group lead for irradiation engineering at ORNL.
“As we demonstrate the reliability of these printed components, we’re looking at a future where Additive Manufacturing might become standard practice in producing other critical reactor parts,” stated Manufacturing Demonstration Facility Director Ryan Dehoff.
What’s next?
ORNL will conduct post-irradiation evaluation of the additively manufactured rabbit capsule this winter.
The capsule’s successful testing is anticipated to help pave the way for the use of other additively manufactured components in safety-critical applications within the nuclear energy community and other highly regulated industries with stringent material composition, design, and qualification standards.
The research team that created the additively manufactured rabbit capsule plans to utilise the geometric flexibility that Additive Manufacturing enables to create more complex designs with unique features that are difficult to fabricate conventionally.
The work was supported by the US Department of Energy’s Advanced Materials and Manufacturing Technologies programme, which aims to accelerate the commercialisation of new materials and manufacturing technologies through demonstration and deployment.