Part 2 of 2 Parts (Please read Part 1 first)
Short and his team did not see the expected slowdown. Short said, “We went in with a hypothesis about what we would see, and we were wrong. You go in guns blazing, looking for a certain thing, for a great reason, and you turn out to be wrong. But if you look carefully, you find other patterns in the data that reveal what nature actually has to say.”
Instead of the slowdown, what did appear in the data was that while a materials would usually produce a single frequency peak for the material’s SAWs, in the degraded samples there was a splitting into two peaks. Short recalls, "It was a very clear pattern in the data. We just didn't expect it, but it was right there screaming at us in the measurements.”
Cast austenitic stainless steels like those utilized in nuclear reactor components are what is known as duplex steels. These are actually a mixture of two different crystal structures in the same material by design. But while one of the two types is impervious to spinodal decomposition, the other structure is vulnerable to it. When the material start to degrade, the difference shows up in the different frequency response of the material. This is what Short’s team found in their data.
Short and his team were surprised by their findings. Short said, “Some of my current and former students didn't believe it was happening. We were unable to convince our own team this was happening, with the initial statistics we had.” They went back to the laboratory and carried out further tests. Those new tests reached a point where the confidence level was ninety nine percent that spinodal decomposition was coincident with the wave peak separation. Dajani said, “Our discussions with those who opposed our initial hypotheses ended up taking our work to the next level.”
The tests they did used big lab-based lasers and optical systems. The researchers are working on the next step to miniaturize the whole system into something that can be an easily portable test kit to use to check reactor components on-site. This will significantly reduce the length of shutdowns. Dajani said, “We're making great strides, but we still have some way to go.” When they do achieve that next step, it could make an important difference. “Every day that your nuclear plant goes down, for a typical gigawatt-scale reactor, you lose about $2 million a day in lost electricity. Shortening outages is a huge thing in the industry right now.”
Dajani added that his team’s goal was to find ways to enable existing plants to operate longer. He said, “Let them be down for less time and be as safe or safer than they are right now—not cutting corners, but using smart science to get us the same information with far less effort.” This new technique seems to offer that.
Short hopes that this could help to enable the extension of power plant operating licenses for some additional decades without compromising safety. The technique enables frequent, simple and inexpensive testing of key components. He says that existing, large-scale plants “generate just shy of a billion dollars in carbon-free electricity per plant each year.” Bringing new plants online can take more than a decade. “To bridge that gap, keeping our current nukes online is the single biggest thing we can do to fight climate change.”