Cascading failures led to the blackout in 11 different western states of the United States, on 10 August 1996, and to the largest blackout in the United States’ history on 14 August 2003 (Crucitti et al., Again, the wider distribution and multiple grid connections of SMRs offer certain advantages here. This makes SMRs a “modular" investment, characterised by the option of small power increments through the deployment of successive units. Each generating portfolio is characterised by its expected return, expressed by the internal rate of return (IRR) and its standard deviation (Markowitz, 1952).