Research report on SASUNE research programme project 3SMR (Small, Safe and Sustainable Modular Reactor)

Small modular reactors (SMRs) are a very attractive option in the near future due to many advantages compared to present day large power plants. One of the major advantages are the improved safety features which are seen as the most important aspect of the innovative reactor designs especially after Fukushima accident in 2011. Another important point of view is the reduced capital cost through design simplification/smaller size in current economic situation. Besides electricity generation, also a wide variety of other applications are available in SMR concepts including process heat production, desalination and hydrogen generation. In addition, SMRs are a potential option for developing countries where grid capacity is not sufficient for large NPPs.

For assessing SMR design attractiveness in national and international level, there is a need to have a closer look at the licensing requirements and related safety issues. This project describes some of the safety features of selected SMR designs, as well as their development status in national and international level, which are discussed in terms of selected disciplines available at VTT. Further, the question is answered about the possible know-how needed at VTT in order to better assist our potential customers in the future.

Based on the literature, it is shown that SMRs are seen as a very promising reactor design in many countries world-wide. In this work, we were focusing mainly on LWR type SMRs due to the their proven technology and knowledge internationally. Many safety features still need to be studied more closely in order to assess the potential difficulties in licensing an SMR plant in Finland, and possibly suggest appropriate changes in the licensing procedures. The extent of passive safety systems and especially the feature of the control room according to which it is possible to control and monitor several reacors at the same time necessitates the new desing of operator work and, consequently, new design of many human factors engineering related activities. There are also some technical challenges that need to be evaluated and tested before deployment of SMRs. This includes especially challenges related to functionality of passive safety systems, evaluation of possible off-site consequences, control room design as well as manufacturing and non-destructive testing of reactor components. In this report, some suggestions are also made on future directions of SMR research at VTT as well as an internal strategy how to follow international development on this topic.