Although the changes in the safety requirements following the Fukushima-Daiichi accident are still not available, the possible generic implications of a safety design option on the SMR economics ( summarised in chapter 4 of reference [8.5]) could be the following:

• On the one hand, broader reliance on the inherent and passive safety features helps achieve the design simplicity “resulting from a reduction of the number of systems and components, and simplicity of plant operation and maintenance, resulting from a reduced number of the systems and components requiring maintenance — both factors contribute to a reduction in plant costs”.

• On the other hand, such factors as the lower core power density and the larger specific volume of the primary coolant (and, correspondingly, the larger volume and mass of the reactor vessel per unit the produced energy), often indicated as safety design features in Tables A2.1-A2.6 of Appendix 2, result in an increase of the specific overnight capital cost of the plant.

Additionally, one should not forget about the intrinsic economic disadvantage of SMRs related to the economy of scale.

In a few cases, such as the CCR, the IRIS, the NuScale, or the Russian marine derivative designs, the containment designs of a nuclear steam supply system appear compact, which could to some extent break the economy of scale law. For example, in the CCR (see Table A1.4 in Appendix 1 and Table A2.3 in Appendix 2) the use of a compact containment is expected to allow reducing the volume of the reactor buildings proportionally to the reactor power, as compared to the currently operated large advanced boiling water reactors (ABWRs). However, the CCR is still at a conceptual design stage and any conclusions about its economics are, therefore, very preliminary.

Many of the advanced SMR designs provide for the reduction of off-site emergency planning requirements (see the last row in Tables A2.1-A2.6 of Appendix 2). According to the designers, such a reduction may be possible due to high levels of safety provided by the design and could help attain certain economic benefits. An issue of the emergency planning zone reduction is discussed in more detail in Section 9.3.

References

[8.1] IAEA (2005), “Innovative Small and Medium Sized Reactors: Design Features, Safety

Approaches and R&D Trends”, Final report of a technical meeting held in Vienna, 7-11 June 2004, IAEA-TECDOC-1451, Vienna, Austria.

[8.2] IAEA (2006), Status of Innovative Small and Medium Sized Reactor Designs 2005: Reactors

with Conventional Refuelling Schemes, IAEA-TECDOC-1485, Vienna, Austria.

[8.3] IAEA (2006), Advanced Nuclear Plant Design Options to Cope with External Events, IAEA-

TECDOC-1487, Vienna, Austria.

[8.4] IAEA (2007), Status of Small Reactor Designs without On-site Refuelling, IAEA-TECDOC-

1536, Vienna, Austria.

[8.5] IAEA (2009), Design Features to Achieve Defence in Depth in Small and Medium Sized

Reactors, IAEA Nuclear Energy Series Report NP-T-2.2, Vienna, Austria.

[8.6] IAEA (2010), “Small Reactors without On-site Refuelling: General Vision, Neutronic

Characteristics, Emergency Planning Considerations, and Deployment Scenarios” Final Report of IAEA Coordinated Research Project on Small Reactors without On-site Refuelling, IAEA — TECDOC-1652 Vienna, Austria.

[8.7] IAEA (2000), Safety of the Nuclear Power Plants: Design Requirements, Safety Standards

Series, No. NS-R-1, IAEA, Vienna, Austria.

[8.8] IAEA (2002), Evaluation of Seismic Hazard for Nuclear Power Plants, safety standards Series,

No. NS-G-3.3, IAEA, Vienna, Austria.

[8.9] IAEA (2004), External Events Excluding Earthquakes in the Design of Nuclear Power Plants,

Safety Standards Series, No. NS-G-1.5, IAEA, Vienna, Austria.

[8.10] IAEA (2004), Status of Advanced Light Water Reactor Designs 2004, IAEA-TECDOC-1391, Vienna, Austria.

[8.11] International Reactor Innovative and Secure (IRIS): www. nrc. gov/reactors/advanced/iris. html

[8.12] Marques M., et al, (2005) “Methodology for the reliability evaluation of a passive system and its integration into a Probabilistic Safety Assessment”, Nuclear Engineering and Design 235, pp 2612-2631.

[8.13] Nayak, A. K., M. R. Gartia, A. Anthony, G. Vinod, A. Srivastav and R. K. Sinha (2007), “Reliability Analysis of a Boiling Two-phase Natural Circulation System Using the APSRA Methodology”, Proceedings of International Congress on Advances in Nuclear Power Plants (ICAPP 2007), Nice, France, May 13-18, 2007 (Paper no. 7074).

[8.14] Web-page of IAEA Coordinated Research Project “Development of Methodologies for the Assessment of Passive Safety System Performance in Advanced Reactors”: www. iaea. org/NuclearPower/Downloads/SMR/CRPI31018/CRP_Programme. pdf

[8.15] IAEA (2009), Passive Safety Systems and Natural Circulation in Water Cooled Nuclear Power Plants, IAEA-TECDOC-1624, Vienna, Austria.