Within present day generation plants, there is a continuing requirement to improve safety and performance. There has been a major investment in experimental and theoretical programmes of work to support this objective. Component research has been carried out to back-fit safety systems on older reactors. Better understanding has led to the development of additional accident prevention and mitigation guidelines. It is also leading to proposals for new systems, e. g. to reduce releases in severe accidents.

There has been a decade of safety upgrades and improvements in nuclear power plants in the EU Accession countries. The main design safety issues are associated with re­licensing, plant life extension, ageing and periodic safety reviews. Another issue is the completion of nuclear power plants that have been left partially built for a number of years (IAEA/NSR/2002, 2003).