The Truth About NIF

Much has been made about the National Ignition Facility – a US Government facility where as massive array of pulsed power lasers is used to irradiate a tiny capsule of deuterium and tritium in order to produce nuclear fusion.  NIF is a truly giant scientific installation, and there’s no disputing its one of the foremost “big science” centers in the world for things like laser optics, pulsed power, plasma physics and nuclear fusion.  The technology is impressive and it will surely produce volumes of important scientific data.

However, there is some confusion, much of it intentional, about the purpose and capabilities of the facility.

It is often portrayed as an experimental prototype for a power-generating fusion reactor.  It’s really not.  The design of the facility precludes it from ever producing useful energy and that’s not the point.  It’s also not the primary objective of NIF to research how nuclear fusion can be harnessed to produce usable energy.  Data to that end may be generated in the process, but the basic design of the facility precludes such a system from being turned into a power plant.

The stated goal of the facility is also often reported inaccurately.  Achieving “ignition” simply means that enough fusion has occurred for additional fusion to be produced without more external power.  In other words, the reaction becomes self-sustaining, if only for a tiny fraction of a second.  Ignition has not yet been achieved, though it is hoped it soon will.  However, it’s less dramatic than it is often described.  The moment when the calculations come back and reveal that the point of ignition has been achieved will not really be that revolutionary.  it won’t mean that suddenly boundless energy is being produced.  After all, nobody doubts that ignition is possible, it is only a question of how much power will need to be concentrated before it actually happens.
Via the Guardian:

Sustainable nuclear fusion breakthrough raises hopes for ultimate green energy
Scientists have moved a step closer to achieving sustainable nuclear fusion and almost limitless clean energy

US researchers have achieved a world first in an ambitious experiment that aims to recreate the conditions at the heart of the sun and pave the way for nuclear fusion reactors.

The scientists generated more energy from fusion reactions than they put into the nuclear fuel, in a small but crucial step along the road to harnessing fusion power. The ultimate goal – to produce more energy than the whole experiment consumes – remains a long way off, but the feat has nonetheless raised hopes that after decades of setbacks, firm progress is finally being made.

Fusion energy has the potential to become a radical alternative power source, with zero carbon emissions during operation and minimal waste, but the technical difficulties in demonstrating fusion in the lab have so far proved overwhelming. While existing nuclear reactors generate energy by splitting atoms into lighter particles, fusion reactors combine light atomic nuclei into heavier particles.

In their experiments, researchers at the National Ignition Facility at the Lawrence Livermore National Laboratory in California use a bank of 192 powerful lasers to crush a minuscule amount of fuel so hard and fast that it becomes hotter than the sun.

The process is not straightforward. The lasers are fired into a gold capsule that holds a 2mm-wide spherical pellet. The fuel is coated on the inside of this plastic pellet in a layer as thin as a human hair.

When the laser light enters the gold capsule, it makes the walls of the gold container emit x-rays, which heat the pellet and make it implode with extraordinary ferocity. The fuel, a mixture of hydrogen isotopes called tritium and deuterium, partially fuses under the intense conditions.

No, they didn’t actually get more energy out of the system than was put in. They just got slightly more energy from the reaction than the amount of energy deposited on the fusion fuel capsule to make it happen.   It’s really not getting us any closer to using nuclear fusion as a limitless energy source.  In fact, it should be noted that this is far from the first time humanity managed to get a lot more energy out of a fusion reaction than was used to initiate it.   That happened in 1952 and was significantly larger.

A few facts to put it in context:

It does not and can not produce usable energy -  When it is stated that the amount of energy produced by the reaction is greater than that which was consumed, that does not mean that there is a full net energy gain for the system.  It only means that the total energy that is deposited on the fuel, by the laser system, is less than the amount of energy produced by the fusion reaction.   It does not mean the total amount of energy consumed by the laser system and all its support equipment, including power converters, cooling systems and alike is less than the energy produced by the reaction.   In fact, of the energy used to drive the laser system, only 1% actually ends up heating the fuel .

Even if more energy were produced by the reaction than is consumed by the systems used to heat the fuel, it still would not mean there was a net gain in usable energy, since that energy is in the form of high energy neutrons, radiation and heat.  In order for that energy to be reused, it would need to be captured and converted into a more usable form, such electricity.  A system to do this might include a large jacket of water to moderate the neutrons and absorb energy, heating it and producing steam to drive a turbine.

NIF lacks such systems to harness the energy of the reaction.  It is hard to imagine how such a system could be incorporated into a chamber that must be open to the many laser beams.  It is conceivable that a large enough system, perhaps on the scale of the PACER proposal could accommodate the reaction and the medium necessary to capture energy, but it would be orders of magnitude larger than NIF.

Even if such a system to recapture energy did exit, it would not be able to harness all the energy of the reaction.  The losses of thermal engines assure that most of the energy would be lost as waste heat.   Thus, for a total net energy gain, the reaction would need to produce a minimum of two to three times as much energy as consumed by all the equipment needed to initiate fusion.

The actual energy of the reaction is surprisingly small - It is often noted that the facility can achieve extreme power levels.  This is true, but only for a tiny fraction of a second.  The total energy that is used to heat the fuel and the amount of energy it can release are actually pretty small.   Reports are that some of the larger reactions have released as much as 17 kilojoules of energy.  Since a joule is the same as a watt-second, 17 kilojoules is enough energy to power a one kilowatt appliance for seventeen seconds.   To put it in terms of metered electricity, the total energy is .00472 kilowatt hours.

This is a tiny amount of energy.  It’s less than the amount of energy a person can expend in one day, if they are doing a lot of athletic activities.  It’s less energy than is in the battery of a laptop or even a large flashlight.

The reason is that there is a tiny amount of fuel to be burned.  The point of “ignition” is where the fusion reaction is sufficient to trigger additional fusion and therefore, in principle, the reaction could be scaled up.  Even if that point can be reached, it still must remain a very small amount of fusion, because the fuel still must fit in a very confined space in order for it to have a chance of being compressed by the lasers.  A large amount of energy would also damage the extremely precise optics and other systems of the chamber.

It is far to expensive to be a practical energy source and that is inherent to the design - Perhaps, maybe, the National Ignition Facility could result in the scientific knowledge necessary to build a better fusion reactor and even create energy.  But the idea that it is somehow a prototype of a future working power plant is simply wrong.  That’s because the complexity of the facility and the complex procedure to operate them makes it impossible that such a facility could serve as a prototype for power producing reactors, even if it were able to achieve the goal of producing consistent energy-producing fusion events.

The facility contains the largest single laser power system ever constructed.  192 high power beam lines receive power from massive capacitor banks producing laser beams that are channeled through a system of precision optics on the target.  The entire facility took years and many billions of dollars to build.  It employs thousands of staff members, both on site and in off-site support roles.

Each time a “shot” occurs, it takes days to prepare, check and recheck the systems.   It is not possible to do so in at a rapid pace, as would be necessary to produce usable energy in any meaningful way.   Many of the components, such as flash lamps and hardware within the target chamber, have limited lives and need frequent checks and replacement.  The fuel capsule itself is not cheap either, being precision manufactured.  The whole thing costs hundreds of millions to operate per year.

Granted, technology does get better and cheaper, but only to a point.  Computing power may follow Moore’s law, but lasers don’t.  Huge quantities of precision optical glass and massive power systems will never be cheap.   Big facilities will always be expensive to construct.  There is simply no escaping that, unless the design is fundamentally changed, a NIF-based power producing plant would be the most expensive source of energy around.  This is true even if it could produce more than a gigawatt continuously.

Simply put: There’s no way anything remotely like NIF could ever be expected to be economically practical as an energy source.

It is not about fusion energy research.  It never was about fusion energy research.  That’s not the aim.  That’s not the point.  That’s just window-dressing – On September 23, 1992, the United States conducted the last test of Operation Julin.  This was the last full scale, critical test of a nuclear explosive by the United States.  It was conducted underground at the Nevada Test Site.  The US suspended nuclear testing after this event.  In 1996, France conducted a series of nuclear tests in the pacific.  That was the last time an “established” nuclear power conducted a weapons test.   There are many reasons for this.  One is that weapons tests are very expensive, requiring deep drilling and massive environmental monitoring.  Another is political, as more and more pressure has mounted against nuclear tests and, increasingly, they seem politically impossible.

The reactions that occur in the NIF test chamber are very similar to tiny H-bombs.  As such, it provides the ability to observe nuclear explosions without actually having to use full scale weapons.   This allows for research into the basic physics behind nuclear weapons and to test certain design concepts.  And, while it has received little press, plans are to incorporate small amounts of weapons grade plutonium into the tests conducted at NIF, thus allowing measurement of how the aging plutonium stockpile reacts to the conditions that occur during a nuclear detonation.

Nuclear weapons research and stockpile stewardship are not only the primary mission of NIF, but are the source of the projects budget.   It is part of the Lawrence Livermore National Laboratory, the primary laboratory concerned with nuclear weapons research in the United States.

This is not to say that the National Ignition Facility will not yield important scientific data on the basics of nuclear fusion reactions, high density plasma or any other important areas of physics.  Better understanding and measurement of nuclear fusion reactions, of the type that occur at the National Ignition Facility can lead to a better understanding of everything from how stars are formed to how shock-waves propagate. It may even lead to knowledge which will someday enable nuclear fusion to be a practical and economical source of energy.  (Although I really would not hold my breath on that one.)

Still, it does not change the fact that the primary purpose of NIF, the very reason it was built, and its most important job is to provide data for use in nuclear weapons research.  All the talk of fusion energy is really just PR.

Conclusion:

I have nothing against NIF.  It’s a great scientific facility and it does produce useful data.  It’s real purpose is nuclear weapons research, which is not something I am personally categorically against.  But it’s not likely to be very useful for energy production research.  But lets call it what it is and be honest about why it exists.

The fact of the matter is that there’s every reason to be skeptical that any course of current research will result in a practical fusion-based energy source.  It’s been researched for decades and no fusion reactors have yet proven effective energy producers.  All large scale experiments have proven complex and expensive.  If you’re looking for a good way of generating energy, it seems fission is just much easier.