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EXECUTIVE SUMMARY: The US Department of Defense has been working with American companies for the past year on a project to develop a prototype for a portable nuclear microreactor, a device intended for use by the US military in security scenarios around the world. The US Department of Energy is also involved in the project, with the aim of providing electricity to remote sites that are difficult to link to the grid. The project thus represents a symbiosis between military and civilian technological development.

A symbiotic relationship between military and civilian aspects of technological development gained momentum in the US after the end of WWII. This was particularly visible among applications in the communication, computing, and aerospace fields, but was also present in the field of nuclear technology. Some technology projects were presented as dual-use in order to justify the cost of their development.

One example of nuclear energy symbiosis was the development of nuclear power-generating reactors. By 1956, more than a decade after the destruction of the Japanese cities of Hiroshima and Nagasaki by nuclear bombs, only the UK’s Calder Hall nuclear power plant, which had four reactors each producing 60 MW electricity (MWe), was in operation. However, as of December 2019, 443 nuclear power generators were operating worldwide, with a total output of 395 gigawatts electric (GWe)—an average output of nearly 900 MWe per reactor.

Eric Klien


A liquid metal lattice that can be crushed but returns to its original shape on heating has been developed by Pu Zhang and colleagues at Binghamton University in the US. The material is held together by a silicone shell and could find myriad uses including soft robotics, foldable antennas and aerospace engineering. Indeed, the research could even lead to the creation of a liquid metal robot evoking the T-1000 character in the film Terminator 2.

The team created the liquid metal lattice using a special mixture of bismuth, indium and tin known as Field’s alloy. This alloy has the relatively unusual property of melting at just 62 °C, which means it can be liquefied with just hot water. Field’s alloy already has several applications – including as a liquid-metal coolant for advanced nuclear reactors.

Zhang and colleagues combined the alloy with a silicone shell through a complex hybrid manufacturing process that combines 3D printing, vacuum casting and so-called “conformal coating” – a technique normally used to coat circuit boards in a thin polymer layer to protect them against the environment. The silicone shell is what allows the lattice to “remember” a desired shape and restore such when the alloy is melted.

Researchers at the US Department of Energy (DOE)’s Oak Ridge National Laboratory (ORNL) are developing a nuclear reactor core using 3D printing.

As part of its Transformational Challenge Reactor (TCR) Demonstration Program, which aims to build an additively manufactured microreactor, ORNL has refined its design of the reactor core, while also scaling up the additive manufacturing process necessary to build it. Additionally, the researchers have established qualification methods to confirm the consistency and reliability of the 3D printed components used in creating the core.

“The nuclear industry is still constrained in thinking about the way we design, build and deploy nuclear energy technology,” comments ORNL Director Thomas Zacharia.

A team of research physicists at Princeton University may have found a new way to control fusion reactions inside doughnut-shaped tokamak reactors — an incremental step towards making fusion energy, the ‘holy grail of energy production’, a reality.

Many fusion reactors today use light elements in the form of plasma as fuel. The problem is that this elemental plasma is extremely hot — practically as hot as the Sun — and extremely unpredictable and difficult to control.

But there may be a way to force the plasma into doing what we want more predictably and efficiently, as detailed in a new theoretical paper published in the journal Physics of Plasmas.

Circa 2017


A brief history of Polywell progress is recounted. The present PIC simulation explains why the most recent Polywell fusion reactor failed to produce fusion energy. Synchronized variations of multiple parameters would require DC power supplies, not available in historic model testing. Even with DC power, the simulation showed that the trapping of cold electrons would ruin plasma stability during start-up. A theoretical solution to this trapping problem was found in Russian literature describing diocotron-pumping of electrons out of a plasma trap at Kharkov Institute. In Polywell, diocotron-pumping required matching the depth of the potential-well to the electron-beam current falling on a special aperture installed in one of the electromagnets. With diocotron-pumping the reactor was simulated to reach steady-state, maximum-power operation in a few milliseconds of simulated time. These improvements, validated in simulating small-scale DD reactors, were scaled up by a factor of 30 to simulate a large, net-power reactor burning p + 11 B fuel. Power-balance was estimated from a textbook formula for fusion power density by numerically integrating the power density. Unity power-balance required the size of the p + 11 B reactor to be somewhat larger than ITER.

Circa 2018 face_with_colon_three


Jong-Kyu Park and colleagues predicted a set of distortions that could control ELMs without any additional instabilities. They then tested these distortions at the Korean Superconducting Tokamak Advanced Research (KSTAR)—a ring-shaped magnetic fusion confinement device. Their experiments worked.

“We show for the first time the full 3D field operating window in a tokamak to suppress ELMs without stirring up core instabilities or excessively degrading confinement,” Park said. “For a long time we thought it would be too computationally difficult to identify all beneficial symmetry-breaking fields, but our work now demonstrates a simple procedure to identify the set of all such configurations.”

This breakthrough means scientists will be able to better predict the distortions for a far larger tokamak—the ITER, the world’s largest fusion experiment that will take place inside the most complex machine ever built. Being able to control the plasma inside the ITER Tokamak will be essential if fusion energy is to be produced from it. At the moment, scientists believe the ITER Tokamak will start producing plasma in December 2025.

Scientists from Princeton University and the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) have used radio frequency waves and temperature to stabilize the white-hot and volatile plasma that swirls inside of fusion reactors like tokamaks and stellarators.

The radio waves disrupt the magnetic islands that form and disrupt the plasma flow, and temperature magnifies the stabilizing effect. As the saying goes, the disruptor of your disruptor is your friend.

Also could do a magnonic fusion reactor.


Magnetic Islands

But there may be a way to force the plasma into doing what we want more predictably and efficiently, as detailed in a new theoretical paper published in the journal Physics of Plasmas.

The Princeton team found that shooting radio frequency waves that super-heat fusion reactions inside a reactor could potentially reduce the chance of “magnetic islands” — bubble-like structures that can throw fusion reactions out of whack by triggering sudden releases of energy.

Alloy 617 — a combination of nickel, chromium, cobalt and molybdenum — has been approved by the American Society of Mechanical Engineers (ASME) for inclusion in its Boiler and Pressure Vessel Code. This means the alloy, which was tested by Idaho National Laboratory (INL), can be used in proposed molten salt, high-temperature, gas-cooled or sodium reactors. It is the first new material to be added to the Code in 30 years.

The Boiler and Pressure Vessel Code lays out design rules for how much stress is acceptable and specifies the materials that can be used for power plant construction, including in nuclear power plants. Adhering to these specifications ensures component safety and performance.

INL spent 12 years qualifying Alloy 617, with a USD15 million investment from the US Department of Energy. A team at INL, in collaboration with groups at Argonne National Laboratory and Oak Ridge National Laboratory, as well as industry consultants and international partners, has now received approval from ASME for the alloy’s inclusion in the Code. Designers working on new high-temperature nuclear power plant concepts now have more options when it comes to component construction materials.