8.1 Introduction

This chapter presents a summary of safety design features for advanced SMRs belonging to different technology lines categorised in Section 4.2. SMR designs that had already been deployed and gained some positive operating experience are not addressed, as the mere fact of their deployment and successful operation is a proof of their conformity to national safety norms. An exception is the KLT-40S floating plant which was still under construction at the time of this report. 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.

In recent years a number of reports addressing safety designs and issues for advanced SMRs were published by IAEA [8.1, 8.2, 8.3, 8.4, 8.5, and 8.6]. Along with the IAEA safety standards and guides [8.7, 8.8, and 8.9] those provided valuable inputs for the consideration performed in this section.

This section makes a reference to Tables A2.1-A2.6 in Appendix 2 of this report, which provide a summary of information on safety design features for each of the addressed SMRs in the following format:

• inherent and passive safety features;

• reactor shutdown systems;

• decay heat removal and depressurisation systems;

• reactor vessel and containment cooling systems;

• seismic design;

• aircraft crash design;

• core damage frequency/large early release frequency;

• emergency planning zone radius (as evaluated by the designer);

• special events considered in safety design (for barge-mounted NPPs);

• compliance with the current regulations.

Reference is also made to Tables A1.2-A1.7 in Appendix 1 of this report, which contains design specifications for each of the SMRs considered.

The structure of this section is as follows. First, safety design features are explained in brief for each technology line, see Sections 8.2-8.7. Section 8.8 provides a summary of safety designs particularly on designs for internal and external events (Sections 8.8.1, 8.8.2), passive versus active safety systems (Section 8.8.3), and safety design versus economics (Section 8.8.4). Compliance with the current regulations and licensing issues that might be faced by some of the advanced SMR designs are then examined in Chapter 9.