MIT researchers have opened the door to more durable metals in fusion power reactors, potentially overcoming one of the key obstacles in harnessing the process that powers stars for carbon-free energy generation. Ju Li, the TEPCO Professor in Nuclear Science and Engineering and a professor of materials science and engineering at MIT, relates that the two main hurdles in fusion energy are creating a net power output and effectively removing the heat generated, with the latter proving to be a tougher nut to crack, as reported by MIT News.
Inside a fusion reactor, plasma generates fast neutrons, which lead to structural wear in the vacuum vessel due to radiation damage and subsequent heat; researchers face the dilemma of finding materials that can withstand these conditions and ensure longevity beyond the currently projected lifespan of six to 12 months, which is a significant departure from the durability observed in nuclear fission reactors that last much longer despite also being bombarded by neutrons. The key issue involves helium, a byproduct of the fusion reaction that penetrates the metal's atomic structure causing weakness and failure, focusing around grain boundaries and amplifying the damage significantly to the point where it threatens the integrity of the entire vessel.
In response to this, the research team at MIT, led by Li, has discovered a remedy: inserting nanoscale particles of a separate material within the metal wall to attract the helium atoms away from the structural weak points, a method both theoretically and experimentally proven to reduce the number of helium bubbles that form at grain boundaries and, consequently, the risk of catastrophic failure. ScD candidate So Yeon Kim and PhD candidate Haowei Xu, along with their collaborators, developed and tested a composite material that utilizes iron silicate as the second material to provide this protective effect.
According to the MIT study, the introduction of just 1 percent by volume of iron silicate into the iron walls of the vacuum vessel could halve the incidence of helium bubbles and reduce their size by 20 percent, making the vessel considerably more durable; Li reassures, "and having a lot of small bubbles is OK if they're not in the grain boundaries," as noted in the same news source. With commercial applications in mind, Li and his team, which includes Alexander O'Brien PhD '23 and former postdoc Kang Pyo So, have already launched a startup to manufacture components using this novel material through 3D printing, integrating the helium-absorbing ceramics into a powder suitable for the process.
The implications of this development reach far and wide with climate change being an ever-pressing concern, as the technology could pave the way for sustainable, large-scale energy production from fusion reactors, leveraging a fuel source as plentiful as seawater-deuterium. This advancement at MIT, under the support of Eni S.p.A. through the MIT Energy Initiative, along with additional support from several U.S. Department of Energy programs and the National Research Foundation of Korea, marks a significant step toward a solution that has been sought after for decades.
