The study analyses the most recent publications on SMR safety, in a large part originating from the International Atomic Energy Agency (IAEA). However, one should keep in mind that the safety features of SMRs will be re-analysed following the Fukushima Dai-ichi accident in order to take into account the lessons learnt from it.

The main conclusions regarding advanced SMR safety are as follows:

• The designers of advanced SMRs aim to implement safety design options with the maximum use of the inherent and passive safety features (also referred to as “by design” safety features). [83]

• In the case of some technologies (like high temperature gas reactors) the incorporation of passive safety features limits the reactor capacity.

• All of the SMR design concepts addressed in this study aim to meet the international safety norms, such as formulated in the IAEA Safety Standard NS-R-1 “Safety of the Nuclear Power Plants: Design Requirements”, regarding implementation of the defence-in-depth strategy and provision of the redundant and diverse active and passive safety systems.

• The available information on safety features of advanced SMRs for plant protection against the impacts of natural and human-induced external events is generally sparser compared to that on the internal events. A certain synergy in coping with the internal and external events is provided by broader incorporation of the inherent and passive safety features (“by design” safety features).

• The core damage frequencies (CDFs) indicated by the designers of advanced SMRs are comparable to, or even lower than the ones indicated for the state-of-the-art large water cooled reactors.