Climate change

June 15, 2010

IFR FaD 5 – the Gen III and Gen IV nuclear power synergy – why we need both

Filed under: IFR (Integral Fast Reactor) Nuclear Power, Nuclear Energy — Barry Brook @ 11:40 am


So far in the IFR Facts and Discussion series, I’ve discussed Gen III and Gen IV fuel cycles and energy densities. In later IFR FaD posts, I aim to explore some possible scenarios for future deployment of the IFR and related technologies. But before I can do this, I need to explain (and justify!), some key underlying concepts — fissile inventory (what Alex Goodwin cleverly called the nuclear ‘spark plug’  in this post on the LFTR), breeding rates, and available fissile and fertile stockpiles. But before I even do that, I should give you the ‘vision thing’.

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After allowing for the benefits from improved energy efficiency, I estimate the world needs to generate roughly 10 terawatts (10,000 gigawatts) of electricity as “clean energy” worldwide by 2050 – a five-fold increase on the energy used today. The world’s current nuclear power capacity, amounting to 380 gigawatts of electricity, has been built up over 50 years. The goal of 10 TWe by 2050 would require a rate of building some 30 times faster. Is that even remotely possible?

To have any realistic chance of achieving this goal — which we must, for the sake of climate change mitigation and peak oil-related energy security — we will need to expand global nuclear power capacity as rapidly as possible over the next 20 years. The most feasible way to do this is by constructing a fleet of generation III+ reactors, such as the AP-1000.

Integral fast reactors and liquid fluoride thorium reactors have so far operated successfully only as demonstration plants and experimental reactors. Nevertheless, a 500-megawatt (0.5 gigawatt) fast reactor is to become operational in India during 2010. Some commercial “generation IV” units have been operated (such as the Phenix fast reactor in France and the BN-350 and BN-600 in Russia) but only a few are currently being built. This is largely because uranium is still plentiful and cheap. That means there is insufficient incentive to invest in this “leap” technology, despite its advantages. Even so, construction is about to start in Russia and China on three BN-800s, scheduled for completion within five years.

As a significant number of generation IV units start to come online over the next few decades, they will need fissile “start charges” to kick them off. A new 1 gigawatt fast spectrum reactor, for instance, needs to be fuelled with about eight tonnes* of fissile uranium 235 or plutonium (or some other mixture of fissile actinides) to get it going. After that, it can breed all the new fuel it will ever need from uranium 238.

Yet, if all of the world’s stockpile of weapons material and used nuclear fuel were reprocessed, we could still produce only enough fissile material (about 3,000 tonnes) to launch just 400 1-GWe fast reactors in the decade 2020 to 2030. After that, if nuclear power is to continue to expand at a rapid rate, we would need a reactor deployment program where we continue to build both generation III and generation IV units for the next few decades.

This program would see the spent fuel from light water reactors reprocessed for use in fast reactors, and new fissile material bred from fertile uranium 238 or thorium 232 in fast reactors. It would take about eight years of breeding** for a fast reactor to create enough new fissile material to start another reactor of equivalent size. (This is called the “doubling time” because the original fast reactor would also continue to operate.)

Only in this way can we achieve the world’s growth path to 10 terawatts (10,000 gigawatts) of nuclear electricity by 2050.

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In the above statement, there are two asterisked sections of text. The justification for the figure of 8 tonnes of fissile per GW, and  years doubling time is really important, but I don’t want to get into the debate about that in this thread. I’ll be happy to argue these figures until I’m blue in the face in IFR FaD 6 & 7, so please hold fire until then.

At a recent uranium conference, I presented a forecast for at least a quadrupling of the thermal reactor fleet (gen III) over the next 25 years, to ~1,500 GWe by 2035.  I’ll talk more about this projection, and the possible extent and technology mix of the gen IV component, in IFR FaD 9 (#8 will be a brief digression on short- and long-term nuclear fuel supply). The chart above is a teaser…

Way back in May 2009, I kicked off a discussion thread called “Should Gen III nuclear power precede Gen IV in Australia?“. It’s interesting to look back at the responses, and reflect on my evolved position. Back then I was uncertain whether Gen III was needed. Why not leap ahead now? More than a year later, I am still consumed by the urgency to get Gen IV going, but Gen III is now certainly also my trusted ally. To explain, let me quote some colleagues of mine from SCGI (we have regular correspondence via a private Google Group).

[The term LWR = light water reactor, that is, gen III thermal reactors (along with heavy water reactors, e.g. CANDU), like the kind now being built by the dozen in China; NRC = US nuclear regulatory commission; S-PRISM = prototype IFR, 300 MWe module; 4S = Toshiba’s nuclear battery (also a sodium-cooled fast reactor)]:

Ray Hunter: “What this country needs now is NRC’s full time attention to get new LWR’s through the process. In addition, industry needs to place many more real licensing requests for LWRs so the country [the US] can begin to make an orderly transition from coal to nuclear. If the government’s mishandling of the waste issue continues to be a deterent for private sector investment for LWRs then we need to proceed with a demonstration facility. When you consider the cost of the waste management i.e.Yucca Mountain, treatment facilities to prepare the material for use in future S-PRISMs can be economical if the private sector becomes the lead as suggested by the new proposed legislation. In summary; A) MANY new LWRs, B) recycle demonstration; C) S-PRISM demonstration”. We could proceed with a IFR demo plant today but we would be missing a key facility required to deal with the LWR waste issue. This is the facility that Yoon has pushing for to demonstate we can convert LWR spent fuel into metal fuel for the IFR. Until this conversion facility is operational, it doesn’t make sense to have a face off between LWR and IFR because the IFR will lose every time. Forget the end of the world strategy, it doesn’t sell.

Bill Hannum: “What we need now for power is many LWRs. In addition, we need to demonstrate the feasibility of efficient recycle in fast reactors, to show that we have a solution to the nuclear waste problem, and a means to utilize essentially all the energy content of the uranium, when and if we need to do this. We do not need a lot of fast reactors now; the LWRs will carry us comfortably for a number of decades. But the political, and public perception that there is no solution to the nuclear waste problem can be removed by a simple demonstration of efficient recycle. The economics can be evaluated after we demonstrate the operational feasibility of such a system. This is laid out in my papers in Tom Blees’ SCGI web site. Disputes as to whether 4-S of S-PRISM or traveling wave reactor is at best a distraction from the need to demonstrate multi-pass recycle in a fast reactor. The key is LWRs now, and demonstrating recycle technology, not the [short-term] transition to a fast-reactor based economy.”

Dan Meneley: “The right path is to build A LOT of thermal reactors right now, quickly, and then move to the IFR. If humanly possible, the thermal reactors should have a high internal conversion ratio. Then the FBRs (aka SFRs) can be brought in as the uranium and thorium prices start to get out of control (as we see happening now with oil). We need to recognize just where the centre of gravity is right now — it’s with the LWR — and plan the IFR program so that it eventually wins, instead of being stamped to death by those nasty and brutish LWR proponents. Saying that “in the end” the IFR will dominate is no solution. It is like saying that a wonderful life awaits us, if we will just stop breathing for a day or two.”

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There’s plenty more discussed within this group on this issue, but you get the gist. We need Gen III, and we’ll need Gen IV. Time to start considering the pathways for getting both of them through and past the current bottlenecks.

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