3D printing of nuclear reactors for entertainment and enrichment

In recent decades, additive technologies , also known as 3D printing, are increasingly found in manufacturing. First of all, they are well suited for prototyping new products - little time passes between development and testing. However, they are increasingly being used in the production of everything from small batches of goods to bespoke casings, and even rocket engine components.



The obvious advantage of additive technologies is that they use non-specific equipment and common materials as resources, they do not need expensive molds as in the case of injection molding, and they do not require a long and wasteful machining process on milling and similar machines. The whole production comes down to feeding a 3D model and one or more input materials to the input of the printing device - and this device turns the 3D model into a physical object with very little waste.



The nuclear industry has not overlooked these advantages. As a result, various components are manufactured on 3D printers - from those that support the operability of existing reactors to tools that help treat spent fuel and even entire nuclear reactors.

This is not your usual fused deposition modeling

Anyone using a 3D printer that works with PLA, ABS or UV-sensitive SLA resin can attest that the cost of producing items this way is hard to beat. The production process of everything from a broken gear in the engine to the special case of a new printed circuit board will be faster and cheaper than traditional ones - if we are talking about making a small number of copies.





Relativity Space prints Aeon Engine



It is because of this that the aerospace industry, from NASA to start-ups in the field, has a warm attitude towards using additive technologies for prototyping and production itself. Rocket engines and their countless components, including turbo pumps and valves, are ideally 3D printed. Each prototype engine is different from the previous one, and in total they are produced several hundred a year - as is the case with the Merlin 1D engine from the SpaceX Falcon 9 rocket. Startups, in particular Relativity Space , suggest that the use of additive technologies will completely transform the space industry.



Naturally, here we are not talking about a printer worth up to $ 2000, which is manufactured using FDM technology (deposition modeling ) plastic parts from PLA or ABS. And not even about fashionable SLA printers ( laser stereo lithography ), which cost a car. To print aluminum, or even titanium parts, you need an SLM ( Selective Laser Melting ) printer, aka a direct laser metal melting printer. This is another step after SLS ( Selective Laser Sintering ) printers , which bond materials together (nylon, metal, ceramic or glass) but not melt them.



SLM is similar to SLA, only the principle of printing is reversed. Fresh metal powder is added on top of the printed part, the laser melts it and adds a new layer. Everything happens in a sealed container filled with inert gas to avoid oxidation. You can guess that the cars for the SLM are already about like a whole house.



For comparison, on the All3DP website there is such a plate that lists the cost of manufacturing a standard Benchy boat model for printing from various metals.

Nuclear reactor

The next natural step in additive technology will be to move from the heat hell of a rocket engine to a quieter - albeit possibly more radioactive - nuclear reactor environment. Nuclear reactors are profitable to be manufactured in large quantities, then economies of scale work. However, over the past decades in the United States, for example, this market has practically disappeared, although it used to be quite extensive.



When former giants of the nuclear industry wanted to return to the game - the USA with the AP1000 reactor and France with the EPR reactor- it turned out that exactly the same nuclear power plants were built in China (having a strong nuclear industry). 4 AP1000 reactors and 2 EPR reactors were connected to the power grid many years before it was planned to build and connect them in the countries that developed them. Ironically, the cooling pumps in the AP1000 made in the USA are subject to constant failure .



The problem of any significant infrastructure project is the availability of the necessary knowledge and supply chains. When a country regularly builds and maintains nuclear power plants, it maintains both the supply chain and the specialists required to work with them. When a country stops building new nuclear power plants for several decades, supply chains disappear and knowledge is lost. Of course, you can rebuild the entire production and attract people, but it makes sense to consider more effective approaches to the production of such equipment.



In an attempt by the United States to catch up with countries such as Canada, Russia [which is in first place in the worldby the number of nuclear power plants under construction] and South Korea, the US Department of Energy assigned Oak Ridge National Laboratory the task of leading the Transformational Challenge Reactor (TCR) program. The program should "demonstrate a revolutionary approach to the deployment of new nuclear energy systems." In essence, the goal of the project is to print as many microreactors as possible on 3D printers to demonstrate the possibilities offered by additive technologies.

Work on details

Working with Argonne National Laboratory (ANL) and Idaho National Laboratory (INL), ORNL is working on the many details involved in this radical change in manufacturing to meet the increased demands on materials used in a nuclear reactor. Questions are raised about heat distortion and fatigue of materials compared to conventional components. Some of the results of these studies are described in a new work , on which you can get an idea of ​​the amount of labor invested in the study of the viability of such an approach.



ANL has already published the discoveries made during the SLM printing process using high-speed X-ray photography, which allows us to examine the process in detail. One of the main problems they found relates to forced airflow, which sucks colder material into the molten mass. As a result, these pieces of cold material lead to defects in the finished product.



In the TCR project fact listdescribes that the microreactor will have to use TRISO (uranium nitride) fuel particles, an yttrium hydride neutron moderator and a 3D-printed silicon carbide and stainless steel core. The reactor will be cooled with helium, which is quite unique, since most modern reactors use water, heavy water or sodium for cooling.



Since the TCR program is quite young (the first publication dates back to 2019), it’s hard to assess its progress or understand what to expect from it. To do this, one can assess what has already happened in the process of integrating additive technologies into the nuclear industry.

Integration of Additive Technologies in the Nuclear Industry

So far, relatively simple components have been printed on a 3D printer for nuclear reactors. In 2017, Siemens replaced a 108 mm impeller in a fire pump at a nuclear power plant in Krsko in Slovenia with a copy printed on a 3D printer. The original pump manufacturer has already shut down since the pump was installed sometime in 1980.



Westinghouse is also working in this direction, and recently installed a 3D-printed clutch on the first Byron nuclear power module . This device holds the fuel rodswhile they sink into the reactor. One of the main reasons for installing it is the desire to understand how the environment of a nuclear reactor will affect materials printed on a 3D printer, and whether there will be a difference with components made in the usual way.

Let's summarize

It is clear that 3D printing has a promising future in manufacturing. In the case of the nuclear industry, it not only offers a good way to produce replacement parts for reactors over 60 years old, more than half of whose suppliers have already closed or changed production. Along with many other new manufacturing technologies, it also offers remarkable new opportunities for the production of next-generation nuclear reactors, whether fusion or decay reactors.



It has many obvious advantages - accelerating prototyping of new reactors and concepts, ensuring the functioning of reactors in remote settlements and future colonies on the Moon and Mars without having to rely on a complex supply chain. The issue of cost is not in the last place - the production of a reactor by this method should be much cheaper, and, possibly, will allow the production and assembly of reactors on the spot.



All this, obviously, is not very interesting for people who do not have access to SLM printers - but who knows, maybe in ten years we will all print our own rocket engines and components of thermonuclear reactors at home.