The importance of facts in research: the IFR

Here’s a sound principle: When writing opinion pieces that criticise internationally renowned scientists, use the best possible information. Especially when the subject is energy, and the object of your criticism sits on the panel for the equivalent of the Nobel Prize for energy: the Global Energy Prize.

When Noel Wauchope criticised Barry Brook’s position on Integral Fast Reactor (IFR) technology (Answering Barry Brook on Australia's nuclear power future 12 June 2012), she didn’t adhere to this principle. While fast reactors are a general suite of technologies, the IFR is quite specific. Just a few months ago, the lead designers of this system, Charles E. Till and Yoon Il Chang from Argonne National Laboratory, published a comprehensive work for the non-specialist called Plentiful Energy. This book explains what the IFR is, how it works, how it was developed, and the host of advantages it brings. It makes it clear why the IFR design is special among fast reactors.

Wauchope’s piece is a litany of confusions and avoidable factual errors. This is dangerous, because bad information risks killing momentum for a technology that will be critical to solving a host of hitherto intractable problems.

Before getting into the details of the IFR, let’s start with a few points of fact. Nuclear energy, in all of its forms, currently supplies approximately 14% of global electricity demand. It is a mature energy source, with over 14,500 cumulative reactor-years of commercial operation in 32 countries. Numerous independent life-cycle greenhouse gas emissions analyses have been done on nuclear energy, from mining through to decommissioning. The verdict? The carbon footprint of nuclear energy is about the same as wind energy, and substantially less than solar photovoltaics, solar thermal and biopower (1). And of course, much, much less than coal. With the development of next-generation technologies, nuclear fission is an inexhaustible source of energy.

Enter the IFR. Developed at Argonne National Laboratory and demonstrated at the Argonne West site in Idaho, USA, from 1984to 1994,this technology was developed specifically to improve the safety, economy, fuel-fabrication process, fuel supply, and proliferation challenges of currently commercial reactors. The IFR is also able to use current stockpiles of nuclear “waste” and even depleted uranium as fuel, increasing the fuel efficiency of the nuclear cycle 150-fold. In fact, we have already mined enough uranium to power the world for hundreds of years using this technology.

Too good to be true? Not according to GE-Hitachi, which is proposing to build a commercial-scale (311 MW) version of the IFR called the Power Reactor Innovative Small Module(PRISM) in the UK right now, to deal with unwanted stockpiles of separated plutonium.

But Wauchope raised the spectre of many serious sounding problems. Is she on the money? She made much of the sodium coolant used in the IFR. True, liquid sodium reacts strongly with air and water. You might stop at the basic characteristic of “reacts with air and water”.  Thank goodness the designers thought a bit harder, and relied on decades of hard-won engineering know-how.

Sodium’s advantages flow through the whole proposition. It is liquid from just under 100°C to beyond normal operating temperatures. So unlike water-cooled reactors, the reactor vessel does not need to be pressurised. This greatly improves safety, and lowers cost by simplifying the overall design and material requirements.

The lack of pressure also permits a roomier “pool and loop” configuration for the coolant. The primary sodium coolant sits in a pool around the reactor, in an inert argon-atmosphere room. A double-walled heat exchanger loop containing non-radioactive sodium flows through the primary coolant in the reactor vessel to absorb its heat, then is routed out of the reactor building to a nearby but separate structure housing the steam generator and turbine. So neither water nor air is ever in proximity to the reactor and its primary sodium pool. The Experimental Breeder Reactor II (EBR-II), the prototype fast reactor built at Argonne National Laboratory, used this cooling process and ran flawlessly for 30 years. How?

The unpressured sodium does not corrode either the stainless steel reactor vessel or the pipes for the coolant loop. Any flaw in the metal would cause a mere trickling leak, detected by sensors, into an inert environment (rather than flashing instantly to steam, as would occur in pipe breaks in highly pressurised water-cooled reactors). Sodium doesn’t react with the specially developed metal alloy fuel either. So if the fuel cladding is damaged somehow, no problem. There will be no blockages from build up of corrosion in the fuel.  The test for this eventuality is called “Run Beyond Cladding Breach”. They ran the test at Argonne Lab, and after 223 days of varying power levels, the fuel was virtually unchanged.

It doesn’t stop there. The sodium coolant has a thermal conductivity far in excess of water. In the event of an emergency shutdown, all residual decay heat is removed completely passively, with no external power required. It is, as Wauchope concedes, as good as meltdown-proof. Emergency shutdown will also occur without any operator intervention. In the event of excess heat from an unexpected power build-up, the metal fuel expands. This causes neutron leakage that renders the chain reaction unsustainable, and once it powers down due to the laws of physics the sodium coolant passively takes it from there. This was tested by initiating the processes of the Three Mile Island and Chernobyl accidents. Nothing happened except quiet shut down. Just as predicted.

As far as Wauchope’s “volatile fission products evaporate from the molten salt”, this makes absolutely no sense since IFRs have no molten salt. She was confused about two very different nuclear reactor technologies. Gaseous fission products are produced when the metal fuel is irradiated, however. The pockets of gas expand in the metal fuel and eventually leaks to a sealed empty reservoir above the fuel pins called the plenum. Just to quote from the designers: “the plenum above the fuel column is sized so the fission gas pressures on the cladding are kept to reasonable levels”.

After about a year and a half, a third of the fuel pins are removed for what is called pyroprocessing. The fuel is separated into the fission products (the relatively short-lived waste), the uranium, and the plutonium and other actinides. The process is good, but not too good, ensuring that the other actinides as well as some uranium and even traces of the highly radioactive fission products remain mixed with the plutonium. This makes it useless as weapons material, and that was the idea all along. Till and Chang say, “a processing technology that also separates a very pure product is exactly what is not wanted...there are basic scientific reasons that make any kind of pure product very difficult, and probably impossible, to obtain”.

Because the metal fuel is such a simple alloy, the cleansed product is simply melted, mixed, drawn towards electrodes, cast as a new fuel slug, and reloaded into the reactor upon the next refueling. It is so radioactive that it must be remotely handled, but also so simple to make that it can be remotely handled. Once in the environs of the power plant, fissile material could never leave the site except under the most deliberate and controlled (read “obvious and slow”) conditions. This reprocessing is not “close by” as Wauchope posits. It’s attached. Integrated. That’s why it’s called the Integral Fast Reactor. The IFR concept design does not produce weapons material at all. It produces a dog’s breakfast mix of plutonium, uranium and other actinides. Useless for bombs, great for fuel. This technology can dispose of practically every atom of fissile and fertile material we have accumulated, giving us electricity in return. It is a massive non-proliferation benefit, and cleans up a legacy of spent fuel and depleted uranium from half a century of nuclear power and weapons technology in the bargain.

The only thing leaving the site is the fission products; small in quantity, short in half-life (around 30 years). It can be turned to glass and stored until it is less radioactive than natural rocks within 300 years. Yet such vitrified waste won’t leach anything into the environment for thousands of years.  There are numerous buildings throughout the world that have been occupied for more than 300 years. Let’s face it; we can either use these reactors to deal with spent nuclear fuel, or bury it as it is and leave it radioactive for thousands of years. No decision is a decision for the status quo. No decision is not an option.

We are just as pleased as any climate-concerned individuals to see the progress and growth in renewable technologies, but let’s not kid ourselves. Quitting fossil fuels fast needs a viable replacement to do the heavy lifting. Nuclear is a high-capital option, just like (but much less so than) solar thermal. Unlike solar thermal, it gives lots of ‘always on’ electricity at a great price. Remember, all the fuel we’ll need to power the whole planet with IFRs for centuries is already out of the ground. It’s not free—it’s better than free. Nations pay to get rid of it. The financial assist nuclear needs is to overcome the capital hurdle and secure financing; from there it takes care of itself. Are we okay with that? You have a vote. You decide. Just understand that the alternative is fossil, not renewable.

Who knows? If we would actually talk about this with maturity, not flippancy, and give due respect to the likes of Barry Brook who have researched these topics intensely and really know their stuff, Wauchope’s “happy hurdles” of public acceptance and legislative blocking might be dealt with pretty quickly. Isn’t that what we want? Great science and deep thinking to help us solve intractable problems?

Till and Chang...these guys did their homework. They knew exactly the problems that nuclear power had, and worked with an all-star team of physicists and engineers to solve them. Wauchope’s piece distorts this picture using the type of wilful ignorance we often call denial. This is not environmentalism. It is anti-nuclear ideology, and its time is nearly up.