Ten per cent was included to demonstrate sensitivity and because it was consistent with the highest rate used in participating countries (including non-OECD countries for their own analyses. ( As noted in IEA/NEA (2010: p. 34), “In keeping with tradition, also this edition of the Projected Costs of Generating Electricity has worked both with a 5% and a 10% discount rate.” Although there has been a tradition of using discount rates of 5% and 10%, there has been some confusion regarding the determination of the discount rate. The key aspect here is the assumption that all risk is captured in the discount rates. For the purposes of this study, it means that when using the term “social resource cost”, we treat the investment in question as if there was no price risk.