First, let me address my view of the definition of "sustainable". This actually is not a simple matter. Many definitions have been offered and there's endless debate about the meaning of this term. To me, something is sustainable if it does not exhaust fundamental natural resource limits and conveys benefits now and to future generations commensurate with it's costs (economical, environmental, social/cultural). Sustainability is a benefit/cost issue. Inter-generational equity is a critical consideration. Thus, there is also the question of the timeframe over which one performs this assessment. Is it 100 years, 1000 years, 10,000 years, "forever" ? From a practical standpoint, given the limits of human knowledge and the progressive nature of science and technology, I tend to adopt the "few hundred years" timeframe for my consideration of such matters. So let's pick 300 years as the time frame for our analysis. That's roughly ten human generations.
Second, it's important to have a context for the amount (volume) of spent nuclear fuel currently generated by the nuclear power industry. As I've noted before, a single 1 Gigawatt electric nuclear power plant produces about 20 metric tons of spent nuclear fuel a year. That's about forty or so nuclear fuel assemblies for pressurized water reactors. The entire of inventory of spent nuclear fuel generated in the U.S. today by every commercial nuclear power plant that has every operated can fit in a spent fuel pool less than 300 feet on a side. (We are NOT generating mountains of spent nuclear fuel in this country.)
My definition of a "sustainable nuclear fuel cycle" is encompassed by five criteria which I term my:
"Five Pillars of a Sustainable Nuclear Fuel Cycle":
- known uranium resources would support it's deployment for at least 300 years (300 years from above definition of sustainability);
- it would be "affordable" and economically competitive to nuclear power produces and energy consumers;
- it would not create unacceptable quantities (volumes) of nuclear waste;
- the radiotoxicity (health risks) of the spent nuclear fuel and fuel cycle wastes would drop to levels similar to that of uranium in the earth's crust after a relatively short period of time which is meaningful in terms of human social, cultural, and government structures;
- its deployment would not present unacceptable dangers from the standpoint of nuclear proliferation.
An exhaustive analysis of these issues is well beyond the scope of a blog posting, and much research has been done and is currently underway around the world today. So just a few comments here...
The amount of uranium "economically" recoverable (Pillar 1) is a matter of some debate and uncertainty. However, given current projections for world-wide growth in nuclear power, it appears we have or will have access to uranium reserves sufficient for somewhere between 100 and 300 years even if the current once-through open fuel cycle continues to be used. So, from the resource utilization standpoint, the current once-through fuel cycle isn't sustainable. Additionally, the current fuel cycle creates wastes (that violate my Pillar 4 above. So the current open fuel cycle is not sustainable and must eventually be replaced. However, we clearly have some time to land upon the solution. (See MIT's recent update of their 2009 fuel cycle study.
So what is my proposed solution? I believe the "solution" is to develop a nuclear fuel cycle (a suite of reactors, nuclear fuels, and nuclear fuel reprocessing technologies) that achieve my Five Pillars with the added specificity that the time frame for application in Pillar # 4 is 300 years (again ~ 10 generations). I'm not the only one thinking this way. Dr. Kathryn Jackson's testimony before the President's Blue Ribbon Commission on America's Nuclear Future this past August promoted a similar view from a leader in the nuclear industry. Dr. Jackson is Westinghouse Nuclear's Senior Vice President and Technology Officer.
As I said, there's much more here to be discussed. But for now, let's think about the Five Pillars of a Sustainable Fuel Cycle, and the Five Imperatives of Nuclear Energy as a framework for workable nuclear energy future – here and abroad.
More on the proliferation issue (Imperative 5) soon...