Nuclear Energy Systems
This definition refers to the section Sustainability Assessment
A Nuclear Energy System (or NES) comprises the spectrum of nuclear facilities and associated institutional measures. Nuclear facilities include facilities for: mining and milling, processing and enrichment of uranium and/or thorium, manufacturing of nuclear fuel, production (of electricity or other energy- related products, e.h., steam, hydrogen), reprocessing of nuclear fuel (if a closed nuclear fuel cycle is used), and facilities for related materials management activities, including storage, transportation and waste management. Within INPRO, all types of reactors (e.g., cooled by light and heavy water, gas, liquid metal and molten salt, of different sizes of thermal power and use, such as for production of electricity, of process and district heat, and of freshwater, and for transmutation of actinides
and fission products) and associated fuel cycles (e.g. U, U–Pu, Th, U–Pu–Th cycle) may be
considered. Institutional measures consist of agreements, treaties, national and international
legal frameworks and conventions (such as the NPT, the International Nuclear Safety
Convention, IAEA Safeguards Agreements) as part of the national and international
infrastructure needed to deploy and operate a nuclear program.
All phases in the life cycle of such facilities need to be considered, including site
acquisition, design, construction, equipment manufacture and installation, commissioning,
operation, decommissioning and site release/closure. In practice, the INPRO Requirements
do not, in all areas, always address each of these life-cycle phases explicitly. But, in
performing an assessment, a variety of IAEA Safety documents (guides, standards, etc.) are
expected to be used and such documents address the life-cycle phases. So, taken as a whole,
the INPRO Requirements do take them into account.
An example of a Nuclear Energy System could be a combination of thermal reactors and fast
reactors, a closed fuel cycle based on plutonium/uranium, reprocessing facilities, centralized
fuel production and waste management facilities.
Clear definition of the nuclear energy system (NES) is needed for an INPRO assessment. As described in the overview manual of the INPRO methodology, the NES will be selected, in general, based on an energy planning study. This study should define the role of nuclear power (amount of nuclear capacity to be installed as a function of time) in an energy supply scenario for a country (or a region or globally). Using the results of such a study, the next step is the choice of facilities of the NES selected that fits to the determined role of nuclear power in the country. The NES definition should include a schedule for deployment, operation and decommissioning of the individual facilities.
Innovative Nuclear Energy Systems
Innovative Nuclear Energy Systems (or INS), in INPRO, encompasses all systems that will position nuclear energy to make a major contribution to global energy supply in the 21st century. In this context , future systems and thus, INPRO, may include evolutionary as well as innovative designs of nuclear facilities.
An evolutionary design is an advanced design that achieves improvements over existing designs through small to moderate modifications, with a strong emphasis on maintaining design proveness to minimize technological risks.
An innovative design is an advanced design, which incorporates radical conceptual changes in design approaches or system configuration in comparison with existing practice. These systems may comprise on only electricity generating plants, but include also plants (of various suze and capacity) for other applications, such as high-temperature heat production, district heating and sea water desalination, to be deployed in developed regions as well as in developing countries in transition.
Given the conservative nature of utilities and the desire of many Member States to use proven technology, the process by which a radical conceptual change is adopted is a topic of considerable importance.
For some considerable period of time nuclear energy systems will consist of a mix of existing, evolutionary, and innovative designs of components. In assessing an INS which includes such an admixture of components, it is likely that some INPRO requirements will need to be modified or not used for some components. Failure to meet all INPRO requirements does not necessarily mean that an INS should not be deployed, since it may be able to make a significant and useful contribution to meeting the energy needs of a given Member State (or region or globally) on an interim basis. An INPRO assessment of such a system is a valid and useful exercise since it will identify the gaps that will need to be addressed to bring the INS into full compliance whit the INPRO requirements and hence with the objective of sustainability.
