Lombardi, and three co-authors, reported in 2008 that if nuclear power is to be sustainable requires the fulfilling of peculiar constraints, which include addressing the proliferation risk [which there is none becasue the current fuel is less than 15% U235.] One possible route for sustainability is that to adopt a fuel cycle based on thorium. However, comparison with uranium cycle indicates that thorium cycle utilization is premature. Instead, a promising short-term option is the use of inert matrix fuels, possibly containing thoria, in a once through cycle. Irradiation tests performed in the Halden reactor show encouraging behavior under irradiation. Furthermore, these fuels are very well suited for a direct disposal in a geological repository [or stored on-site indefinitely with minimal hazard]
The authors concluded that nuclear is considered today (in 2008) a sustainable energy source under the criteria of economics, safety, availability of resources and impact on the environment. But the social acceptability is not granted by [only a few], and the aspects linked to the environmental impact [without foundation], as the recycle of wastes [although on-site storage is not a hazard (more)], will need to be more and more improved. But there is a further requisite for sustainability, peculiar to nuclear power, consisting in the resistance to nuclear armaments proliferation [but this is irrelevant to the subject at hand]. It is an important aspect, which dictated the nuclear policy of the USA and influenced the one of other countries. The solution can be found through a combination of agreements among nations, modifications to fuel composition and improvements to reprocessing technology.[Also not relevant.]
The new nuclear – excluding fusion – is often identified by the public opinion with novel reactors and cycles, above all the reactor proposed by professor Rubbia (ADS) and thorium bearing fuels, which should represent a radical turn. From one side we are witness of a visionary attitude (dreaming machine and reprocessing), which proposes an accelerator driven subcritical fast reactor with thorium–uranium closed cycle þ new reprocessing technology þ
totally remote fuel fabrication. This can solve a real problem, i.e. the proliferation risk, and the perceived ones, i.e. waste toxicity, plant safety, and optimal resources exploitation.
From the other side we can find a radical rational attitude, claiming that the recycle is not justified: advantages are uncertain and far in the future, disadvantages are real and in the present. The authors concluded that the best way to follow is a co-existence of technologies: thermal and fast reactors; uranium, thorium and inert matrix bearing fuels; closed cycle in breeder reactors, semi-closed cycle with fissile topping, once-through cycle with deep fissile (and/or minor actinides) burning and fuel fit for the direct geological disposal. In particular, we focused on the latter option, as it can be implemented in present water reactors with relative small efforts and in a relatively quick time.
The use of inert matrix and thoria fuels appears as an excellent short-term option to eliminate the proliferation risk [BS] associated to plutonium, and to lower its long-term radiotoxic inventory. The demonstration of the feasibility of inert matrix and thoria fuels will alleviate the concerns about these two issues, until a more efficient and sustainable nuclear technology will be available.
[Not withstanding the above 2008 views, thorium is being included in some current reactor designs]
Managed & Built by I2M Consulting, LLC | © 2010-
