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The IAEA Safety Standards Series include, in a hierarchical manner, the categories of Safety Fundamentals, Safety Requirements and Safety Guides, which define the elements necessary to ensure the safety of nuclear installations. In the same way as nuclear technology and scientific knowledge advance continuously, also safety requirements may change with these advances. Therefore, in the framework of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) one important aspect among others refers to user requirements on the safety of innovative nuclear installations, which may come into operation within the next fifty years. In this respect, the major objectives of the INPRO subtask “User Requirements and Nuclear Energy Development Criteria in the Area of Safety” have been: a. to overview existing national and international requirements in the safety area, b. to define high level user requirements in the area of safety of innovative nuclear technologies, c. to compile and to analyze existing innovative reactor and fuel cycle technology enhancement concepts and approaches intended to achieve a high degree of safety, and d. to identify the general areas of safety R&D needs for the establishment of these technologies. During the discussions it became evident that the application of the defence in depth strategy will continue to be the overriding approach for achieving the general safety objective in nuclear power plants and fuel cycle facilities, where the emphasis will be shifted from mitigation of accident consequences more towards prevention of accidents. In this context, four high level user requirements have been formulated for the safety of innovative nuclear reactors and fuel cycles. On this basis safety strategies for innovative reactor designs are highlighted in each of the five levels of defence in depth and specific requirements are discussed for the individual components of the fuel cycle.

In May 2001, the IAEA initiated the “International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO)”. Having in mind that nuclear power will be an important option for meeting future electricity needs, the scope of INPRO covers nuclear reactors expected to come into service in the next fifty years, together with their associated fuel cycles. INPRO has been implemented in two phases. In the framework of its Phase 1A, the task group Safety of Innovative Nuclear Systems examined the needs to be met by innovative nuclear systems and defined, in a hierarchical order, a corresponding set of Basic Principles, User Requirements, and Criteria. In this context, an enhanced defense-in-depth strategy is considered as a dominant part in the fundamental safety approach. For each of the five levels of protection, a user requirement indicates the direction of the enhancement (e.g.: no need for evacuation, even in case of severe accidents) and, in general, more independence of the levels from each other shall be achieved.

For the past couple of decades there has been a change of emphasis in the world nuclear power from that of building new Nuclear Power Plants (NPP) to that of taking measures to optimize the life cycle of operational plants. National approaches in many countries showed an increase of interest in Plant Life Management (PLIM), both in terms of plant service life assurance and in optimizing the service or operational life of NPP. A strong convergence of views is emerging from different National approaches, particularly in the area of the economic aspects of NPP operation and in the evolution in the scope of NPP PLIM. The latter can directly affect the cost of electricity from NPP in an increasingly competitive environment. The safety considerations of a NPP are paramount and those requirements have to be met to obtain and to extend/renew the operating license. To achieve the goal of the long term safe, economic and reliable operation of the plant an Integrated Life Cycle Management Programme (ILCMP) is necessary. Some countries already have advanced PLIM Programmes while others still have none. The ILCMP objective is to identify all that factors and requirements for the overall plant life cycle. The optimization of these requirements would allow for the minimum period of the investment return and maximum of the revenue from the sell of the produced electricity. Recognizing the importance of this issue and in response to the requests of the Member States the IAEA Division of Nuclear Power implements the Sub-programme on “Engineering and Management Support for Competitive Nuclear Power”. Four projects within this sub-programme deal with different aspects of the NPP life cycle management with the aim to increase the capabilities of interested Member States in implementing and maintenance of the competitive and sustainable nuclear power. Although all four projects contain certain issues of PLIM there is one specific project on guidance on engineering and management practices for optimization of NPP service life including decommissioning. This particular project deals with different specific issues of NPP life management including aspects of ageing phenomena and their monitoring, issues of control and instrumentation, maintenance and operation issues, economic evaluation of NPP life cycle management including guidance on its earlier shut down and decommissioning. The paper describes in detail the full scope IAEA activities on different issues of NPP life management and some of its achievements in this field during the nearest past as well as plans for the future.