Once it is built and operating, an NPP will become subject to a different set of commercial risks. These include retrospective changes in policy or practice in regulation, electricity pricing, taxation, competition from other generators or even the rules governing NPP ownership. These may impact on the profitability of the plant and, naturally, will be borne by the plant sponsor or owner. During a 60 year plant life we may, for instance, expect some less profitable or even unprofitable years when electricity prices fall during an economic downturn. But the business case that was used to justify the construction of the plant at the outset should have included a market analysis that examined the probability and the consequences of, for example, an excess of supply over demand along with other possibilities such as changes in fuel prices (including those of the main competitors), carbon prices, electricity pricing, exchange rates, running costs and so on.

The sums of money that are involved in electricity generation are so large that, regardless of whether the plant sponsor is a private-sector or a state-owned utility, the making of a strong and robust business case is essential to justify the investment. Where the state is the owner, however, it does, at least, have the ability to frame the rules over such things as carbon pricing, electricity trading and taxation so that they work to its advantage. A private-sector utility, does not have this power of course. Rather, when considering the possibility of an investment it seeks assurances that, for example, the rules governing electricity trading and the outlook for carbon pricing will remain unchanged or will move in his favour for the foreseeable future and, further, that there is a consensus on this across the political divide. Governments will usually wish to see competition and diversity in the electricity market and may encourage new entrants through tax incentives and other ways of subsidising renewables, carbon capture, district heating, micro-generation or whatever. Such schemes may represent a threat to existing generators, who will always seek to ensure that the fundamental assumptions on which the original investment was made are not undermined.

This brief discussion makes clear why would-be generators of nuclear electricity spend years negotiating with governments on such matters as taxation, the rules for electricity trading, policy on reducing future CO2 emissions and the planning system. Governments on their part will aim for an electricity generation system that is least cost, secure, diverse and, increasingly, low in carbon emissions. Incentives that are currently used to encourage the growth of renewables may be extended to other low-carbon technologies such as nuclear and carbon capture.