J-P Laurent
Vice-President
Quality, Safety and
Environmental Protection
COGEMA
2 et 4, rue Paul Dautier
78140 -
Velisy-Villacoublay
Phone: 33 01 39 26 30 00
ABSTRACT
A generally accepted definition of sustainable development is that it is "development which meets the needs of present generations without compromising the ability of future generations to meet their own needs".This principle was strongly supported by the participants to Rio Conference in 1992. In particular, it was recommended to make the most efficient use of natural resources and to minimize the production of waste.
In the field of nuclear energy, the reprocessing-conditioning recycling (RCR) policy clearly responds to such requirements, from several perspectives:
- The primary purpose of RCR policy is to save natural resources of uranium and to avoid the dumping of the valuable materials contained in spent-fuel assemblies; 96% of the material included can be recycled, producing the energy equivalent of 20,000 toe per ton of heavy metal reprocessed.
- The long term radiotoxicity of ultimate waste is reduced as low as reasonably achievable by the same process, since beyond 100 years it is predominantly related to the residual plutonium content; in La Hague, reprocessing extracts and recovers 99.98% of the plutonium contained in spent-fuel.
- Another positive effect of reprocessing is to reduce the volume of high level waste and long-lived waste, as low as 0.5 m3 per ton of uranium in spent-fuel, to be compared with 2 m3/t from direct disposal according to published designs.
- The benefits from RCR policy implementation will mainly come in the long run, for the future generations, since they will consist of preserved energy resources and smaller quantities of long-lived waste in repositories; that means the burden of environmental impacts is more fairly born by today electricity consumers;
- Moreover, the current performances of La Hague reprocessing plants demonstrates that the actual present burden of such a RCR policy can be minimized, down to negligible levels. Radioactive releases to the sea and to the atmosphere have been constrained to very small amounts and the resulting radiological exposure of the neighouring population remains lower than one hundredth of the exposure to natural radioactivity. The site routine program of sampling and measurement both in the sea and on the land encompasses more than 20,000 samples and 80,000 analytical results each year; it ensures permanent monitoring of the local radiological state. A monthly report is published by La Hague plant to divulged the released quantities and the results of environmental monitoring. Direct access to the data is also possible by televideo means.
The excellent environmental performances achieved by the RCR industry confirm the edge of nuclear energy over other energy sources as concerns environmental protection and long term sustainability. It also sets an example of present industrial, efficient material recycling to the benefit of future generations.
The Environment Rio Summit held in 1992 ended with a public commitment of industrial countries in favor of sustainable development. Sustainable development has been defined by the World Commission on Environment and Development as 'development that meets the needs of the present without compromising the ability of future generations to meet their own needs'. Among others, sustainable development calls for much more emphasis on conserving natural systems and the resource base on which all development depends.
Besides, the world's energy use will rise in the coming decades because of population growth, economic and social development, and increasing demand for the services which energy provides. Therefore, the best possible use of available energy resources must be made, notably by increasing recycling and energy conservation, and minimizing the volume and toxicity of ultimate waste.
There is no doubts that the Earth's fossil energy resources are limited, especially in gas and oil, whatever the various estimates are. Hydropower development will remain limited and other renewable energies can only contribute, marginally and locally, to the energy mix under any scenario.
Against this background, the use of nuclear energy associated with fuel recycling is a fully coherent policy, as it combines two major advantages. The first is the large quantity of uranium available on the planet, which definitely makes it a resource for the future. The second is that nuclear fuel has the specificity of being recyclable to a very large extent, leading subsequently to a lesser amount of waste generated through the production process, thus contributing to the environment.
France's long standing reliance on nuclear energy meets such a commitment toward sustainable development, which leads to drastic reductions of toxic emissions and to an improvement of air and water quality. Spent fuel reprocessing significantly contributes to environmental protection and conservation of natural resources.
ENERGETIC BENEFITS OF THE REPROCESSING-CONDITIONING-RECYCLING STRATEGY (RCR)
A Resource Management Strategy
When introducing the role of reprocessing and recycling strategy for a better use of uranium, Glenn T. Seaborg stated that: «Plutonium is the key that unlocks the energy potential of uranium. Even though some 40% of their energy is derived from burning plutonium in place, today's commercial power reactors extract less than 1% of the energy value of the uranium they consume.» (Glenn T. SEABORG, ANS Meeting, Oct.30th, 1995).
As a matter of facts, in terms of natural resources, large quantifies of uranium are available throughout the World, and there is no doubts about the stability of the supply. With its outstanding energetic content, uranium happens to be an extremely efficient fuel. It however becomes really competitive when using plutonium through recycling process. Actually, no other fuel contains up to 95% of reusable materials after it has been through the process, nor does any other have the potential for multiple recycling. These unique features make nuclear power a prime candidate for sustainable energy development scenario.
Recycling can result in at least a 30% saving of natural uranium and of associated front-end services (conversion, enrichment). When put in a global perspective, the world's nuclear power reactors produce annually 50 tons of plutonium. Full-scale plutonium recycling would represent an energy equivalent to up to 100 Millions TOEs (ton oil equivalent) per year, with an added 50 Millions TOEs for uranium recycling, leading to an energy production level comparable to the North Sea oil production.
When a spent fuel assembly leaves a reactor, it still contains valuable components. The "ashes of combustion" consisting of fission products represent only 3% of the spent fuel, while its uranium and plutonium content are 96% and 1%, respectively.
The uranium is still enriched, with a fissile U235 grade of between 0.8% and 0.9%, while the plutonium's fissile isotopes are about 70% of the whole quantity. The recoverable energy from plutonium through recycling in the current reactors is 1 to 2 TOE per gram. Such a tremendous amount of energy is not to be thrown away. After separation, uranium and plutonium can be used again producing mixed oxide fuel assemblies (MOX) for reactors.
Therefore, spent fuel reprocessing allows natural resource conservation, which corresponds to the same logic as oil, gas, wood or coal conservation, i.e.:1 ton of Pu = 100 tons of U = 1 000 000 tons of oil.
Today, 19 reactors in Europe are loaded with MOX, and the number should reach 40 to 50 around the year 2000. Meanwhile, nearly 25 tons of plutonium will be recycled each year, representing the equivalent of 25 million tons of oil.
COGEMA's Industrial Experience
COGEMA currently operates industrial scale capacities in the reprocessing and recycling business, for which France is the leading country.
The La Hague plant has already reprocessed over 10 000 metric tons of LWR spent fuel from European countries and Japan.
At the MELOX fuel fabrication plant in Marcoule, in operation since 1995, more than one assembly can be fabricated per day. With an objective of 100 tons of heavy metal per year in 1997 and 210 tons by the turn of the century, MELOX is the largest plant of its kind currently in operation worldwide. It brings COGEMA's total MOX fabrication capacity to over 170 tons by next year.
Today, out of the EDF 55 Pressurized Water Reactors (PWRs) in service, nine are loaded with 30% MOX core. EDF plans to extend such MOX fuel use to most of its twenty-eight 900 MWe PWRs by the end of the century: seven others are already licensed for this purpose, and another twelve are technically suited to be loaded as well.
From past experience, in-core MOX fuel performances are excellent and comparable for reactors operations to the UOx fuel. To date, the French program of moxification has accumulated more than 20 reactor-years of significant and positive results thanks to in- depth industrial cooperation.
Today, the entire RCR chain is already fully in operation. Recycling is not a mere technical possibility, it is a physical reality. It allows for the recovery of some 20,000 TOE per ton of spent fuel. The positive results yielded by the French program have encouraged COGEMA and EDF to pursue the recycling policy with a long term view, which makes it possible to balance the quantities of plutonium recovered through reprocessing and the quantity of plutonium integrated into MOX fuel assemblies.
ENVIRONMENTAL BENEFITS OF RCR
A Contribution to the Environment
The highly recyclable feature of spent fuel leads to very minor quantity of waste to be disposed of. Through RCR, the volume and the toxicity of the ultimate conditioned residues to be disposed of are reduced.
The comparison between a closed fuel cycle and an open cycle shows clearly the benefits of the RCR in terms of waste volume reduction.
Let us consider a feed of 8 uranium oxide assemblies into a LWR. In the closed cycle, the plutonium recovered from the reprocessing of 7 uranium oxide assemblies can be recycled to produce 1 MOX fuel assembly: which means electricity can be produced from 8 assemblies with only one final spent fuel.
When considering the amount of final waste to be disposed of, it comes that, in the open cycle the total volume is about 8 m3, while in the closed cycle it is only about 1.6 m3 including two glass canisters.
Moreover, in the near future, the spent MOX fuel assembly could also be reprocessed itself for further reuse, enabling to decrease again the volume of the final waste.
On a more global scale, one should emphasize the contribution of nuclear energy to the reduction of greenhouse gas emissions. Since global climate change may be considered as a major threat, greenhouse gas emissions from electricity generation chains are focusing the attention of decision makers at the national and utility levels.
In the French case, recent analyses indicate that nuclear power is one of the best options for alleviating the risk of global climate change. Worldwide, the present nuclear electricity generation, as a substitute for fossil fuels, is reducing the carbon dioxide emissions from the energy sector by some 8%. For the sole Europe, nuclear industry avoids the reject of up to 700 millions tons of C02 per year. In particular, France has the lowest level of carbon dioxide emissions per inhabitant all over Europe. France is only producing some 350 Mt/year of CO2, while Germany is producing about 850 Mt/y and USA over 5200 Mt/y. The extent to which greenhouse gas emissions may be reduced will depend on national policies regarding nuclear power. Even if one may argue that the increase of the greenhouse effects remains to be proven, yet it seems clear that in applying the precautionary approach, in compliance with the Rio declaration, all cost-effective measures must be implemented to prevent an environmental degradation, including the use of nuclear energy.
Furthermore, as far as waste is concerned, the French RCR policy is in line with the ALARA principle in minimizing both volume and toxicity of final residues.
COGEMA has launched far-reaching programs aimed at minimizing waste, through the compaction of hulls and end-pieces, and the reduction of technological waste originated in the reprocessing operations. Today, the total volume of high level waste produced is already less than it would be in the direct disposal of spent fuel option. With 0.5 m3/t today, it is expected to be below this value by the year 2000.
Along with waste minimization, waste management efficiency is of paramount importance. Each type of process waste is conditioned with respect to precise technical specifications. However, in order to facilitate subsequent management by the producers, both in interim storage and in final disposal facilities, by limiting the type of containers, a 'universal canister' approach is being implemented for vitrification fission products and compacted hulls and end-pieces. It is also planned to extend the same compaction and conditioning to technological waste from remote control areas. By the year 2000, the universal canister will be available on a commercial scale for use in either of the afore mentioned situations, reducing transportation, storage and disposal costs.
Radioactivity Reduction from RCR Strategy
Waste volume minimization is not the only environmental benefit of a closed fuel cycle. Indeed, plutonium represents the vast majority of the radiotoxicity contained in spent fuel, extracting it from the fuel reduces the radiotoxicity of waste to be buried.
Actually, systematic use of plutonium allows to burn some Pu within reactors instead of producing some; therefore reducing, as for a same quantity of electricity produced, the amount of plutonium generated.
Furthermore, as plutonium is recovered and is thereby cut by a factor 1000, only 0.1% of the plutonium contained in spent fuel remains in the final waste, so the radiotoxicity of the final waste is significantly decreased. Therefore, the environmental impact of these activities is not only very low in operating conditions, it is also minimized in the long term.
Another advantage to recycling is that, since the plutonium is removed from the waste, as opposed to what occurs in the direct disposal option, it does not lead to the creation of plutonium mines buried underground, which might create a potential source of hazard for future generations. In other words, reprocessing and recycling turn the problem of safe long term disposal into an opportunity for energy generation.
CONCLUSION
With regards to the requirements outlined for sustainable development, nuclear recycling is the optimal solution for the back end of the fuel cycle, as it makes the best possible use of available energetic resources, minimizes the volume and toxicity of final waste, and emits virtually no greenhouse gases.
The reprocessing and recycling industry has reached its industrial maturity and operates with extremely stringent safety and environmental protection standards. In addition to these measures, the industry displays intrinsically advantageous characteristics for environmental protection compared to other options for back end management. In contributing to a rational use of natural, the reprocessing and recycling industry demonstrates its advantages in terms of sustainable development.