Nuclear Fusion Reactor, the dream of unlimited source of clean, cheap energy moving towards reality

myidst.com29 November 2015

Many energy experts believe that nuclear fusion is the only real ‘solution’ to global warming that is capable of producing unlimited supplies of cheap, clean, safe and sustainable electricity. The reactor’s fuel is limitless, hydrogen the element used to create the fusion reaction is the most abundant atom in the universe and could be sourced from seawater, and the lithium found in the Earth’s crust. Fusion reactors are also safe (they produce less radiation than we live with every day); clean (there’s no combustion, so there’s no pollution); and will create less waste than fission reactors.

Lasers could heat materials to temperatures hotter than the center of the Sun in only 20 quadrillionths of a second, according to new research.

Theoretical physicists from Imperial College London have devised an extremely rapid heating mechanism that they believe could heat certain materials to ten million degrees in much less than a million millionth of a second.

The heating would be about 100 times faster than rates currently seen in fusion experiments using the world’s most energetic laser system at the Lawrence Livermore National Laboratory in California. The race is now on for fellow scientists to put the team’s method into practice.

Rising Energy Demands and need of new and renewable energy

In the last 25 years, the number of megacities in the world has grown from 10 to 28, home to nearly half a billion of the human race. By 2030, the number is expected to increase to 41. The rise in megacities would lead to enormous energy demands.

The current world’s energy consumption, which is estimated today to be 12 billion tons oil equivalent (TOE) could increase twofold or threefold by the start of the 22nd century. In parallel, the fossil reserves (oil, coal and natural gas) are being depleted, while the cost to extract and exploit them is increasing. Lastly, climate change forces us to seek energy sources that emit less GHGs. Our ability to transition from fossil fuels to renewable sources of energy will likely determine the fate of the planet.

The world is seeing the thrust in development of new and renewable energy sectors emitting few or zero GHGs, particularly Solar, wind and water power. Under a historic deal between the U.S. and China, China pledged that solar and wind power would account for 20 percent of China’s total energy production by 2030. Denmark, which aims to completely eliminate its use of fossil fuels by 2050, will rely on its cutting-edge wind power industry. Germany has focused on solar and wind power in its push to remake its electricity system, and Brazil now derives more than 75 percent of its electricity from hydro-power sources

Researchers from US, Europe, Russia, China and Japan are striving towards harnessing immense energy of nuclear fusion, the process that powers the Sun and produces 10 thousand times more energy than coal.

However the thermonuclear fusion has proved extremely hard to achieve on Earth with any great intensity or consistency over the past six decades. Fusion demands an enormous energy input, which is almost always greater than the energy it creates, resulting in a net energy loss, “Fusion is an expensive science, because you’re trying to build a sun in a bottle,” said Michael Williams of National Spherical Torus Experiment, and “The true pioneers in the field didn’t fully appreciate how hard a scientific problem it would be.” The necessary materials are either too expensive or simply do not exist.

There are two leading methods being used today to produce nuclear reactions, with lasers and with magnets. Laser fusion squeezes hydrogen atoms together to the point that they fuse with each other to create helium – this is the same nuclear fusion process that occurs in the center of the sun.

The other form of nuclear fusion is using hot plasmas that are contained by powerful magnetic fields. Atoms within the plasma recombine and in the process release energy. This type of nuclear reaction is produced in large containment vessels called tokamaks.

International Thermonuclear Experimental Reactor (ITER)
International Thermonuclear Experimental Reactor, or ITER, is a collaborative scientific effort backed by the European Union and six other nations, including the United States. The multi-billion-euro ITER facility, currently under construction in Cadarache southern France, will be largest fusion reactor ever. ITER has now expanded into a 35-country project with an estimated $50 billion price tag.

The scientific goal of the ITER project is to deliver ten times the power it consumes. From 50 MW of input power, the ITER machine is designed to produce 500 MW of fusion power—the first of all fusion experiments to produce net energy. ITER will use magnetic fields to contain the hot fusion fuel – a concept known as magnetic confinement.

The project has graduated from the design stage to the construction phase. However, there is at least another decade of building work and a further decade of testing before the reactor will be allowed to “go nuclear”.

Applications in Nuclear weapons program
The very hot and dense conditions encountered during an Inertial Confinement Fusion experiment are similar to those created in a thermonuclear weapon, and have applications to the nuclear weapons program. ICF experiments might be used, for example, to help determine how warhead performance will degrade as it ages, or as part of a program of designing new weapons.

It has been argued that some aspects of ICF research may violate the Comprehensive Test Ban Treaty or the Nuclear Non-Proliferation Treaty. In the long term, despite the formidable technical hurdles, ICF research might potentially lead to the creation of a “pure fusion weapon”.

Lockheed Martin Pursuing Compact Nuclear Fusion Reactor Concept
The Lockheed Martin’s Skunk Works® team is working on a new compact fusion reactor (CFR) that can be developed and deployed in as little as ten years. According to an article published by Reuters on Wednesday, McGuire told reporters that Skunk Works has already successfully shown the company can build a 100-megawatt reactor that measures seven by 10 feet, or around 10 times smaller than what is currently available.

“Our compact fusion concept combines several alternative magnetic confinement approaches, taking the best parts of each, and offers a 90 percent size reduction over previous concepts,” said Tom McGuire, compact fusion lead for the Skunk Works’ Revolutionary Technology Programs. “The smaller size will allow us to design, build and test the CFR in less than a year.”

Lawrence Livermore National Laboratory
NIF, $3.5bn facility based at the Lawrence Livermore National Laboratory, is one of several projects around the world aimed at harnessing fusion.

The scientists of National Ignition Facility (NIF) created a breakthrough during an experiment in September 2013, when the amount of energy released through the fusion reaction exceeded the amount of energy being absorbed by the fuel – the first time this had been achieved at any fusion facility in the world. Since then, the National Ignition Facility at Lawrence Livermore National Laboratory in California has reproduced such fusion at least four times.

One of LLNL’s latest achievements, announced last February, was when an LLNL team extracted 10 times more energy from their nuclear fusion reactions compared to past experiments. They published their results in the journal Nature.

To do this, they utilized a process called boot-strapping. Boot-strapping takes some of the residual particles created during fusion and deposits their energy into the overall fuel supply source instead of letting the particles escape.

NIF uses 192 powerful laser beams are focused through holes in a target container called a hohlraum, a 9.425-mm-long, 5.75-mm-diameter cylindrical gold cavity. Inside the cavity is a 2 mm spherical pellet containing a frozen deuterium-tritium (D-T) mix surrounding cooled D-T gas, in a silicon-doped plastic coating. The fuel pellet is made by adding gaseous deuterium and tritium and then cooling to 18.6 kelvins, or –254.55 degrees Celsius.

The hohlraum target—about the size of a pencil’s eraser—sits within a spherical target chamber 10 meters in diameter, which in turn is positioned inside NIF’s “Grand Central Station,” a concrete silo target bay 30 meters high and 30 meters in diameter.

Lasers are fed with roughly 500 megajoules of electricity, which then pump out 1.9 megajoules worth of energy in slightly more than a nanosecond, delivering 500 terawatts of power inside the hohlraum (a terawatt is a trillion watts).

When the concentrated beams simultaneously hit the gold hohlraum, they create X-rays within the cavity that blast off the fuel pellet’s silicon-doped plastic coating. The remainder of the pellet is driven inwards in an implosion, compressing the fuel inside the capsule and creating a shock wave that adds more heat to the fuel and creates a “burn.”

But while a net-energy-positive reaction is an important technical achievement, the facility’s core goal of ignition—a self-sustaining fusion reaction—still appears to be many years off.

University of Washington Fusion Experiment
University of Washington has also taken hot plasma approach for building nuclear fusion reactor. According to their estimate if their technique becomes successful then it would cost $2.7 billion to produce 1 billion watts of power whereas modern coal plants require $2.8 billion to produce the same amount of energy.

One of the reasons for their cost effectiveness is their unique design of tokamaks which is spherical in shape rather than traditional hollowed-out doughnut shape. “Right now, this design has the greatest potential of producing economical fusion power of any current concept,” said UW Professor of aeronautics and astronautics, Thomas Jarboe, in a statement released by the university.

Now, researchers at the University of Washington have stepped up their existing involvement in the fusion field with a $5.3 million Department of Energy grant to scale up their “Sheared Flow Stabilized Z-Pinch” fusion device

Uri Shumlak, a professor in the department of aeronautics and astronautics, co-leads the project and explained that the Z-Pinch technique is smaller and cheaper than more conventional magnetic field coil-driven reactors.

China is also pushing its own tokamak reactor program, EAST (Experimental Advanced Superconducting Tokamak) reactor is a higher-level tokamak than any found in the U.S. It utilizes superconductive magnets (which no reactor in the United States currently does), which gives it a superior capability in magnetic confinement strength.

They are now conducting experiments to extend the duration of fusion production to more than 400 seconds, working toward steady-state operation of a fusion machine.

Shenguang Laser Project for Inertial Confinement Fusion
China is also well on its way to developing an inertial confinement fusion (ICF) facility comparable to the laser fusion facility at the National Ignition Facility (NIF) at Livermore. The Shenguang (Divine Light) laser project explores the inertial confinement fusion (ICF) as an alternative approach to attain inertial fusion energy (IFE) – a controllable, sustained nuclear fusion reaction aided by an array of high-powered lasers.

Shenguang’s target physics, theory and experimentation, began as early as 1993. By 2012, China completed the Shenguang 3 (Divine Light 3), a high-powered super laser facility based in the Research Center of Laser Fusion at the China Academy of Engineering Physics – the research and manufacturing center of China’s nuclear weapons located in Mianyang.

Divine Light 3 (SG-III), facility is designed to utilize up to 48 energetic laser beams (six bundles) and laser energy output of 150-200kJ (3ω) for square pulse of 3 ns. If fast ignition is workable, SG-III will couple with a PW laser of tens of kJ to demonstrate fast ignition. SG-III will be used to investigate target physics before ignition for both direct-driven and indirect-driven ICF.

Although the facility is currently only in the target design experimental phase, the next phase, Divine Light 4(3 ns, 3ω, 1.4 MJ), will be for ignition of actual fuel. Shenguang aims to achieve such “burn” – fusion ignition and plasma burning by 2020, while advancing research in solving the complex technological challenges associated with controlling the nuclear reaction.

In this context, Shenguang has two strategic implications: it may accelerate China’s next-generation thermo-nuclear weapons development, and advance China’s directed- energy laser weapons programs.

Russia has launched a $1.5 billion project to create a high-energy superlaser site that would be capable of igniting nuclear fusion. The facility will be used both for thermonuclear weapon and for inertial confinement fusion (ICF) studies.

Internationally this will be the fourth international facility of megajoule-class Lasers for ICF and High Energy Density Science after NIF in the United States, LMJ (Laser MegaJoule) in France and Divine Light 4 in China.

The laser facility will be developed by the Research Institute of Experimental Physics (RFNC-VNIIEF), a leading Russian nuclear laboratory. In its six decades of history, it was involved in the development of both the military and civilian nuclear programs in Russia.

It will be a dual-purpose device, “On the one hand, there is the defense component, because high energy density plasma physics can be productively studied on such devices, which is necessary for developing thermonuclear weapons. On the other hand, there is the power industry component. The world’s leading physicists believe that laser nuclear fusion can be useful for future energetics,” the head of research, Radiy Ilkaev said.

The Russian device will be similar to the American National Ignition Facility (NIF) and the French Laser Mégajoule (LMJ) in terms of capability. Ilkaev says the future Russian facility will be able to deliver 2.8 megajoules of energy to its target, as compared to energy levels of about 1.8 megajoules for the American and French lasers. “We are making our device later than they did, because such projects are costly, but ours will be the best in the world,” the scientist promised.

According to Ed Moses, head of the NIF, “This latest Russian announcement demonstrates that laser fusion continues to grow rapidly as an international effort. One of the interesting attributes of these systems is that the size of the investment in showing full-scale burn physics can be managed within the resources of individual countries (as demonstrated above) and that the time scale of construction is now 10 years and decreasing.

The HiPER effort in Europe is also exploring building large facility capabilities to study fusion energy and the Koreans have recently shown significant interest in exploring this path within their own country.

Many within the field think that this trend will accelerate in the years ahead as the system designs for advanced systems become better understood, the basic technologies continue to become more commercial, and that the physics performance of laser fusion, in whatever configuration, becomes more robust.”
Experts say science has made a lot of progress recently and for some, confidence is high.

“For $20 billion in cash, I could build you a working reactor,” Professor Steven Cowley, CEO of the UK Atomic Energy Authority, told Popular Mechanics. “It would be big, and maybe not very reliable, but 25 years ago we didn’t even know if we’d be able to make fusion work. Now, the only question is whether we’ll be able to make it affordable.”