Periodic Safety Reviews and Safety Cases

Continuous improvement in nuclear safety is a critical success factor for the nuclear industry. Most nuclear facilities therefore perform a systematic safety reassessment, known as a Periodic Safety Review (PSR). NRG has supported the nuclear industry for over 30 years with consultancy and technical services relating to licensing and safety assessments, including PSR.

A PSR aims to ensure a high level of safety throughout the plant’s operating lifetime. It includes an assessment of plant design and operation against the current licensing base, the applicable current safety standards and operating practices. IAEA Safety Standard SSG-25 prescribes a general methodology for the PSR of Nuclear Power Plants. A similar methodology can also be applied to the PSR of other nuclear facilities like Research Reactors and Waste Storage Facilities.

As principal engineer, NRG was responsible for the main elements of the PSRs and the resulting modifications to the Borssele Nuclear Power Plant. This included assisting in the evaluation of the overall plant safety, rules & regulations and defining measures and design modifications.

NRG also contributed to the recent periodic safety reviews of the Petten Research Reactor and the Waste Storage Facility COVRA.


Safe operation is vital for the nuclear industry. For new or modified nuclear facilities, it is therefore common to make a Safety Case. NRG helps nuclear facilities prepare a strong and solid Safety Case.

In a Safety Case, safe operation of the facility is ensured by demonstrating that it fulfils the fundamental safety principles for nuclear installations, taking into account any additional inspections, tests, procedures and operational limits and conditions. The fundamental safety principles include the ‘defence in depth’ and the ‘multiple barriers’ concepts. Deterministic and probabilistic safety analyses are also an important part of the Safety Case.

For a solid Safety Case, it is important to use the knowledge and experience of the operating staff, as they know the facility like no other. NRG also contributes its own know-how and expertise. Consequently, our consultants have the skills to perform the entire Safety Case. Safety assessments by NRG often result in a number of practical recommendations to further improve safety.