ASME, EPRI, the US DOE, the National Research Council of Canada and various manufacturers are cooperating to bring advanced manufacturing technologies to the nuclear power industry.
Technologies such as electron beam welding and powder metallurgy hot isostaticaly-pressed materials are being employed in new reactor designs to reduce cost and rapidly accelerate the deployment of small modular reactors (SMRs).
Additive manufacturing (AM) is another promising technology that is making its way into the nuclear power industry. Known more commonly as 3-D printing, AM encompasses a number of technologies that can be grouped under the ASTM material codes.
- Binder Jetting (BJ)
- Direct Energy Deposition (DED)
- Material Extrusion (ME)
- Powder Bed Fusion (PBF)
- Sheet lamination (SE)
- Vat Photo Polymerization (VP)
Any particular AM process can be employed in one of 4 interrelated activities.
The first three activities are typically associated with AM and are used in a number of industries (including the building of SMR’s) to reduce part weight, to consolidate parts, and to efficiently produce complex designs.
But the AM industry has developed a number of applications that can be employed in the cost-effective repair or replacement of obsolete components. DED can be used to restore the damaged parts layer-by-layer whether this is by laser cladding, laser metal deposition or powder bed fusion.
In each application of DED for repair in a nuclear environment there will be several challenges including geometric complexity of the object, the object’s end-use conditions (temperature, stress, radiation levels, etc.), interface requirements (including tolerances) and base material compatibility that will determine the impact AM material selection, machine selection and post processing requirements.
Typically, the process to choose the best AM repair path will require many of the same steps that would be required to replace the entire part.
- Create a digital model of the component
- Characterize the base material – chemical composition, hardness, yield strength
- Characterize the component’s end-use conditions – environmental, stress, tolerances
- Evaluate the AM process options
- Plan and execute process trials
- Evaluate the trial outcome against the end-use criteria
- Proceed with the AM repair
Developments in AM have and will continue to revolutionize the Nuclear power generation space; reducing costs and improving turnaround times to complete repairs and develop new products. Advancements in AM are fundamental in shifting Nuclear quality standards in the years to come.