Safety of Nuclear Power Reactors
One of the important issues that are limiting the wider use of nuclear energy for electricity production in the European region is the level of safety of several of the current type of nuclear power reactors in operations in some European countries. The EC started to discuss safety issues in 1975, when nuclear power programs promoted by different European states had progressed and diverged along very different routes, including different legal frameworks, types, and number of reactors, as well as national systems regulating them in force in several countries (Morales Pedraza 2008).
There were important differences in safety requirements for the safe operation of nuclear power reactors in Western and Eastern Europe. These differences make more difficult the search for a common acceptable solution to this sensitive problem. The level of safety to be applied to nuclear power reactors produced in Russia and other Eastern and Central European countries was higher than the safety level applied in the past. This situation forces the EU, for the first time in the history, to start in the 1990s the process of carrying out an evaluation of nuclear safety in Eastern and Central Europe, particularly in those countries asking for their entry in the EU. The debates on nuclear safety in the context of the enlargement of the EU raised vital questions about what are the Western standards for nuclear safety. The objective to be reached within this debate is to ensure that all European member states would have equivalent levels of nuclear safety, particularly after the Fukushima Daiichi nuclear accident. This by no means implies that the operator of nuclear power reactors should not retain the primary responsibility for the nuclear safety of the nuclear power reactors under the control of the national regulatory bodies, but to have minimum common nuclear safety standards that should be applied by all European countries.
Over the past 20 years, reactor safety has improved significantly, both inside and outside the European region. No early generation of Soviet (Chernobyl-type) light water graphite reactors (LWGRs) is in operation in the EU, and the present cohort of the European nuclear power reactors has had a good overall safety record. Since 1986, accident probabilities have decreased substantially because of improvements in reactor technology, peripheral equipment, and operating practices, and these elements have been reinforced further after the Fukushima Daiichi nuclear accident. Most of the European nuclear power reactors are equipped with confinement domes, ascertain- ing that, in the occurrence of an accident, radioactive material are not released to the external environment and the consequences associated with the accident are controlled to a minimum. Man–machine interactions in plant operation have been considerably perfected, and a better safety culture has been established through the creation of an international “early notification system,” obliging operators to report any incident using the International Nuclear Event Scale (INES) of the IAEA. Continued efforts in maintaining and elaborating high safety standards, particularly after the Fukushima Daiichi nuclear accident, are among the actions carried out by the operators of nuclear power plants for an expansion of nuclear power in Europe (Morales Pedraza 2008).
Opportunities exist for reactor safety enhancement through research and development of new nuclear power reactor designs. Innovative designs for nuclear power reactors that make greater use of passive-safety features and build on the construction and operation experience gained in today’s nuclear power reactors already in operation. The EPR and the high-temperature reactor (HTR) are examples of new types of reactor designs (Generation III and III+). EPR is among the nuclear power reactor designs more likely to be used in the construction of new nuclear power reac- tors in the European region in the near future. The nuclear power reactors presently under construction in Finland and France are of this type, while in the long-run the HTRs type of nuclear power reactor may be added to existing nuclear capacity.
Furthermore, the EU is in the process of creating new directives to further improve nuclear power reactor operation safety and develop regulatory safety oversight at a European level, particularly after the Fukushima Daiichi nuclear accident. Among the issues that will be addressed in the new directives are the ascertaining of sufficient funds for the complete decommissioning of nuclear power plants, the exchanging of best operational practice for existing nuclear installations, the maintaining of high safety standards for nuclear power plants whose operation licenses are extended, and the providing of transparency for citizens related to the operation of nuclear power plants.
It is important to highlight that the design of nuclear systems in Europe relies on the “defense in depth” principle. It consists in the prevention of accidents and the mitigation of their consequences and the protection of workers and populations against radiological hazards through the use of multiple barriers and safety systems. For the more recent nuclear power reactor systems such as Generation III or III+ reactors, even extremely improbable accidents are taken into account. For example, the EPR was designed so that in the very unlikely event of a severe accident, radiological consequences would necessitate only very limited protective countermeasures in a relatively small area and for a limited time for the surrounding population.