El presidente francés, Emmanuel Macron, anunció recientemente que Francia invertirá mil millones de euros en energía nuclear y construirá más reactores para 2030 para ayudar a evitar la crisis energética de Europa.

Pero incluso en Francia, donde la energía nuclear proporciona más del 70 % de la combinación energética del país, el tema es controvertido.

El debate está especialmente polarizado entre quienes viven cerca de las centrales nucleares, según se beneficien o no material o simbólicamente de esta proximidad. También existe una tensión constante entre la prensa y el sector nuclear por la cobertura de la industria.

Décadas desde que se construyó la primera planta de energía nuclear, el debate aún se ve obstaculizado por malentendidos sobre las ventajas y desventajas de esta tecnología.

Opiniones contrastantes

Como físicos, los dos estamos de acuerdo principalmente en los fundamentos científicos y tecnológicos del debate, y en todos los argumentos basados ​​en hechos verificables. Pero nuestras diferentes sensibilidades como ciudadanos nos llevan a sopesar cada argumento de manera diferente y llegar a conclusiones diferentes sobre la energía nuclear.

Uno de nosotros (Stefano Panebianco) estima que las ventajas de esta tecnología la convierten en una opción viable para el futuro, mientras que el otro (François Graner) estima que nuestros esfuerzos deben centrarse en una disminución significativa de nuestro consumo de energía.

Al basarnos en nuestros puntos de vista contrastantes basados ​​en una comprensión compartida de la evidencia científica, queremos ayudar a otros a formarse una opinión enumerando los pros y los contras de la energía nuclear utilizando los métodos rigurosos de nuestra vida cotidiana como científicos.

Para hacerlo, pedimos a expertos de todo el espectro, incluidos físicos, economistas, politólogos, antropólogos, historiadores, periodistas y voluntarios de ONG, que contribuyeran a una revisión de las principales cuestiones relacionadas con la energía nuclear. Los trabajos recopilados no brindan una conclusión:dejamos que los lectores saquen la suya propia.

Entonces, ¿cómo deberías decidirte? Estos son los conceptos básicos.

Tomar decisiones sobre el futuro

La física subyacente a la producción nuclear de electricidad es bien conocida. Es más bien la industrialización del proceso lo que plantea interrogantes.

Las organizaciones de investigación científica y tecnológica intentan anticipar las necesidades energéticas futuras y desarrollar nuevos tipos de reactores nucleares para reemplazar los existentes. Dicha investigación no debe predecir las elecciones futuras que deben hacer los políticos y la sociedad. Sin embargo, es un proceso a largo plazo que a menudo lleva varias décadas de investigación, diseño, desarrollo y experimentación antes de la aprobación y, por lo tanto, las opciones de las direcciones de investigación actuales pueden ser un tanto vinculantes para el futuro.

Por ejemplo, el estudio del diseño y la optimización de reactores reproductores de neutrones rápidos es un campo de investigación de larga data. Esto permitiría reciclar el combustible nuclear, lo que preservaría los recursos naturales de uranio y reduciría los desechos nucleares.

In France, two successive demonstrators, Phenix and Super-Phenix, were built and operated last century and a third one, Astrid, was planned in recent years. However, all of these projects have been subject to successive government decisions to pursue, stop, resume, and recently in the case of Astrid, stop again, or at least defer. These decisions were made based on economic, environmental, political and strategical criteria.

How much does it cost?

Natural uranium, which is used as fuel in power plants, is still a relatively abundant resource and does not yet contribute much to the total cost of nuclear energy.

The French Court of Auditors estimated the current average generation cost of nuclear energy for a life-span of 50 years at €60 per megawatt-hour, equivalent to six cents per kilowatt-hour. Though comparisons with other electricity sources are difficult to make, the highly variable public sale price of electricity is around 15 cents per kilowatt-hour.

Cost estimates heavily depend on hypotheses about the future, including the prolongation of power plant duration, waste choices and the decommissioning of reactors. Although decisions are often taken within the short-term vision of an electoral mandate, waste policy must take long-term implications into account.

Meanwhile, the technical feasibility of decommissioning is still hard to predict owing to different levels of understanding of the various reactor types. To maintain or decommission a nuclear power plant requires anticipation in term of money, know-how and energy, and so largely engages the next generations.

Nuclear power thus requires long-term political, financial and geological stability.

Is it safe?

In public debates about safety, a purely technical subject has been transformed into a political one.

Radioactivity must be controlled throughout all stages of the nuclear fuel chain to prevent any harmful effects on either humans or the environment. The risk of nuclear accidents, whether related to natural events, human error, waste, malice or war, has been addressed over the decades by significant improvements and by experience feedback from the two main accidents of Chernobyl and Fukushima. However, it remains a major preoccupation for the general public.

Preventing accidents involves many factors, including the human one; the know-how and motivation of workers depend on a strong partnership between operator and subcontractors.

Other environmental impacts during normal operations include the exposure of nuclear workers and the public to chemical or thermal emissions:the latter becomes problematic with the global warming, as river water required to run reactors becomes scarce and warmer.

Does nuclear have a role in fighting climate change?

What is the future of nuclear power? Scientists cannot make predictions. Instead, scenarios are useful tools for examining possible consequences and costs of hypotheses or choices, for instance by decreasing greenhouse gas emissions or even decreasing energy demand.

The fact that nuclear power plants do not emit carbon, at least during the phase of electricity production (as opposed to the whole fuel and plant life cycles), is an argument to consider in the context of bringing down global emissions.

Nuclear plants also deliver constant power, which is a drawback in terms of adaptation to demand, but an advantage in terms of regularity:development of intermittent renewable energies such as solar and wind exert pressure on electricity distribution networks, as these energies are not necessarily always available at peak times.

The role of politics

In practice, global energy transition scenarios are often used to establish and endorse choices that have already been made.

Globally, the decisions which have actually been taken rely heavily on geopolitics, for instance attempts to bring down reliance on petrol imports, and also decisions to develop military nuclear power alongside energy policy.

The dual system of funding civil and military research alongside one another is only justified if nuclear weapons are developed, which is again a political decision.

Why it's so hard to decide

In deciding what to think about nuclear power, the list of arguments to take into account is frustratingly large, and many are coupled together. For instance, some reactors, loaded with the so-called mixed uranium and plutonium oxide fuel, partly contribute to recycle some nuclear products. Shutting them down could have the side effect of filling the current waste storage facilities more quickly than expected.

Even worse, decisions are often based on speculative hypotheses due to the difficulty of prediction. What is beyond doubt is that any decision taken or not taken today will affect future generations more than our own.

This means citizens should not leave decisions to be taken only on the basis of scientific or technical arguments, but should make up their own minds, taking into account the political and societal horizon they want for themselves and their children.