The Michigan Engineer News Center

From global to local: improving nuclear reactor safety, reducing costs

By 15, Annalisa Manera knew she wanted to study theoretical physics. "I was curious about astrophysics and relativity theory and excited about particles and quantum mechanics," said the now-associate-professor of NERS and head of the U-M Experimental and Computational Multiphase Flow Laboratory.| Medium Read

By 15, Annalisa Manera knew she wanted to study theoretical physics. “I was curious about astrophysics and relativity theory and excited about particles and quantum mechanics,” said the now-associate-professor of NERS and head of the U-M Experimental and Computational Multiphase Flow Laboratory.

Manera’s father was a civil engineer and, concerned about future job prospects in theoretical physics, gently nudged her toward engineering. She learned that nuclear engineering involved a lot of physics; it seemed like a good alternative.

It has been. Manera went on to earn a master’s degree from the University of Pisa and did her master’s thesis and PhD work in thermal-hydraulics at Delft University of Technology.  She spent two years working as research scientist at the Research Center Rossendorf/Dresden Institute for Safety Research.

From Dresden she went to Switzerland to gain industry experience and, later, began working for the Paul Scherrer Institut (PSI). Within less than a year she was heading her group, providing technical support for nuclear power plants and the Swiss nuclear authority. She also performed R&D on the development of advanced computational tools for nuclear plant transient simulations.

“We got to work on real problems, real transient situations, which was a great experience for me because, in academics, there can be a danger of being disconnected from reality,” she said.

Ready for a new challenge after five years, Manera applied for faculty positions at MIT and U-M. The welcoming, collegial atmosphere in NERS quickly impressed her. “The environment felt very collaborative; I could tell I would fit well here,” she said.

Since her arrival, Manera has developed a robust research program focused on thermal-hydraulics, to make nuclear reactors safer and more economical. Her group designs physics-based passive safety systems and develops high fidelity experiments to validate the computational tools and refine models that simulate plant behavior.

“In the past, in thermal-hydraulics, you would have a few local sensors for pressure, temperature, flow rates and other variables, and from this you would derive global correlations,” Manera explained.

But those correlations would be limited to specific geometries and operational conditions.

“Now, we’re designing our experiments to be less global and more local, with measurements characterized by high spatial and temporal resolution. This allows us to investigate physical phenomena at smaller scales, which are not as affected by the specifics and are more transferable,” she added.

In the past few months, Manera’s lab received $1.2 million in funding for three projects.

The first, with the U.S. Department of Energy, involves high-resolution experiments and computational fluid dynamic simulations to better understand the interaction of buoyant jets in stratified environments, such as in a light water reactor during a loss-of-coolant accident. Such an understanding is critical to avoiding accumulation of hydrogen and potential explosions like the one at the Fukushima Daiichi plant.

In a project with the Nuclear Regulatory Commission (NRC), Manera and her team are designing and building two systems for high-resolution measurements of two-phase flows at high pressure. One is based on gamma tomography; the other on time-resolved X-radiography. A former colleague from PSI in Switzerland will work as a post-doctoral research fellow in Manera’s lab on the project.

In a second NRC project, Manera is using high-resolution experimental data on two-phase flows to improve models of the dynamic evolution of the liquid-vapor interface.

“We focus on high-resolution experiments — that’s the strength of our group, how we can bring new insights and drive advances on the modeling side,” she said. “If you don’t have the insight into the physics, you can’t improve the models. Having a foot in both experimentation and modeling means we understand the strengths and deficiencies of both worlds, and we know how to bridge them.”

In addition to her research, Manera has developed two undergraduate courses — Fluid Mechanics for Nuclear Engineers (NERS 344) and Thermal-Hydraulics of Nuclear Systems (NERS 444) — and a graduate course on Computational Fluid Dynamics for Nuclear Applications (NERS 547).

With courses established and many key projects underway, Manera’s group is gaining momentum and generating results.

“It’s a productive time,” she said, “a time for collecting the fruits of three years of sowing seeds since coming to U-M, and this, to me, is very exciting.”

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Steven Winters
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Nuclear Engineering and Radiological Sciences

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The electrons absorb laser light and set up “momentum combs” (the hills) spanning the energy valleys within the material (the red line). When the electrons have an energy allowed by the quantum mechanical structure of the material—and also touch the edge of the valley—they emit light. This is why some teeth of the combs are bright and some are dark. By measuring the emitted light and precisely locating its source, the research mapped out the energy valleys in a 2D crystal of tungsten diselenide. Credit: Markus Borsch, Quantum Science Theory Lab, University of Michigan.

Mapping quantum structures with light to unlock their capabilities

Rather than installing new “2D” semiconductors in devices to see what they can do, this new method puts them through their paces with lasers and light detectors. | Medium Read