The Nuclear Fuel Cycle: The French Example and How to Learn from It

The nuclear fuel cycle is the series of stages that nuclear fuel goes through, from mining to disposal. It involves the preparation, use, and management of spent fuel, which is the fuel that has been used in a nuclear reactor and is no longer efficient. The nuclear fuel cycle can be open or closed, depending on whether spent fuel is reprocessed or not. Reprocessing is the process of extracting uranium and plutonium from spent fuel, which can be reused in new fuel assemblies. In this article, we will explore the French example of the nuclear fuel cycle, which is based on recycling spent fuel, and how other countries can benefit from it.

Why recycle spent fuel?

France is one of the countries with the highest share of nuclear energy in its electricity production, with 58 nuclear power reactors generating about 72% of its electricity in 2018. However, this also means that France produces a large amount of spent fuel and radioactive waste, which need to be safely managed and disposed of. To deal with this challenge, France has decided to close its nuclear fuel cycle by recycling or reprocessing spent fuel. This way, the nuclear industry can recover and reuse the uranium and plutonium contained in spent fuel, reducing the volume and toxicity of high-level waste. Recycling spent fuel is also a way to optimize the use of natural uranium resources, as it allows to extract more energy from the same amount of uranium.

Recycling spent fuel is an important element of the French nuclear sector’s strategy, which has more than 30 years of experience in this field. According to Denis Lépée, deputy director of nuclear fuel division at EDF, the French electricity company that operates the nuclear power plants, “recycling spent fuel reduces the volume of materials and waste, and safely packages them”.

How does recycling work?

The process of recycling spent fuel involves converting the used plutonium (a by-product that forms in nuclear power reactors when uranium fuel is burned) and uranium into a “mixed oxide” (MOX), which can be reused in nuclear power plants to produce electricity again. The MOX fuel contains about 7% to 10% of plutonium and 90% to 93% of uranium. The MOX fuel can be used in some of the existing reactors, called pressurized water reactors (PWR), which are the most common type of reactors in France and in the world. Currently, 22 out of the 58 French reactors are licensed to use MOX fuel.

The recycling process takes place in two main facilities: the Orano La Hague plant, where spent fuel is reprocessed, and the Orano Melox plant, where MOX fuel is fabricated. The Orano La Hague plant, located in Normandy, is the largest reprocessing plant in the world, with a capacity of 1,700 tons of spent fuel per year. The plant has been operating since 1976 and has processed more than 34,000 tons of spent fuel so far. The Orano Melox plant, located in the south of France, is the world’s leading producer of MOX fuel, with a capacity of 195 tons of MOX fuel per year. The plant has been operating since 1995 and has produced more than 2,000 tons of MOX fuel so far.

The recycling process involves several steps:

• The spent fuel assemblies are transported from the nuclear power plants to the Orano La Hague plant in special containers, under strict safety and security measures.
• At the Orano La Hague plant, the spent fuel assemblies are cut into small pieces and dissolved in nitric acid. The uranium and plutonium are separated from the fission products (the radioactive elements that are formed when uranium atoms split) and the minor actinides (the heavy elements that are formed when uranium and plutonium atoms absorb neutrons) by a chemical process called PUREX (Plutonium and Uranium Recovery by EXtraction).
• The separated uranium and plutonium are converted into solid forms: uranium oxide (UO2) and plutonium oxide (PuO2). The uranium oxide can be reused in the fabrication of new fuel assemblies, after being enriched to increase its fissile content. The plutonium oxide is sent to the Orano Melox plant for the fabrication of MOX fuel.
• The fission products and the minor actinides are mixed with glass and poured into stainless steel containers, forming a solid and stable matrix called vitrified waste. The vitrified waste is the main form of high-level waste in France, and it accounts for about 4% of the volume of spent fuel. The vitrified waste containers are stored in interim storage facilities at the Orano La Hague plant, waiting for a final disposal solution.
• At the Orano Melox plant, the plutonium oxide is mixed with depleted uranium oxide (which is the leftover uranium after the enrichment process) to form MOX powder. The MOX powder is then pressed into pellets, which are loaded into fuel rods. The fuel rods are assembled into MOX fuel assemblies, which are transported back to the nuclear power plants for use.

What are the benefits and challenges of recycling?

Recycling spent fuel has several benefits, such as:

• Reducing the volume and toxicity of high-level waste: Recycling spent fuel allows to recover about 96% of the reusable materials (uranium and plutonium) and to reduce the volume of high-level waste by a factor of five8. Moreover, recycling spent fuel reduces the long-term radiotoxicity of the waste by a factor of ten, as the plutonium, which is the main contributor to the long-term radiotoxicity, is removed and reused.
• Optimizing the use of natural uranium resources: Recycling spent fuel allows to extract more energy from the same amount of uranium, as the plutonium, which represents about 1% of the natural uranium, can be used as a fuel. Recycling spent fuel can increase the energy yield of natural uranium by about 12%.
• Enhancing the security of supply: Recycling spent fuel reduces the dependence on uranium imports, as France has limited domestic uranium resources. Recycling spent fuel can reduce the uranium consumption by about 17%.

However, recycling spent fuel also poses some challenges, such as:

• Increasing the complexity and cost of the fuel cycle: Recycling spent fuel involves more steps and facilities than the open fuel cycle, which increases the technical complexity and the operational cost. According to the French Court of Auditors, the cost of recycling spent fuel is about twice as high as the cost of the open fuel cycle.
• Raising proliferation and security concerns: Recycling spent fuel involves the separation and handling of plutonium, which is a fissile material that can be used to make nuclear weapons. Therefore, recycling spent fuel requires strict safeguards and security measures to prevent the diversion or theft of plutonium.
• Delaying the final disposal of high-level waste: Recycling spent fuel does not eliminate the need for a final disposal solution for high-level waste, as the vitrified waste still contains long-lived radionuclides that require isolation from the biosphere for thousands of years. Recycling spent fuel may also create additional waste streams, such as the MOX spent fuel, which has different characteristics than the conventional spent fuel and may require specific disposal conditions.

How can other countries learn from the French example?

The French example of recycling spent fuel is unique in the world, as France is the only country that has a large-scale and industrialized recycling program. Other countries, such as Japan, Russia, the United Kingdom, and India, also have some experience in recycling spent fuel, but at a smaller scale or for different purposes. The United States, which has the largest nuclear power program in the world, has opted for the open fuel cycle and does not reprocess its spent fuel.

However, other countries may be interested in learning from the French example, as recycling spent fuel may offer some advantages in terms of waste management, resource optimization, and security of supply.