Far from nuclear power being reliable and renewable supplies being unreliable, the facts suggest the exact opposite. We can forecast production from wind turbines or solar farms hours in advance, but you cannot predict the sudden breakdowns in nuclear power plant. You don't need to look at the Fukushima crisis to understand that - just look at the UK where Sizewell B, the most modern British nuclear power station, went offline in May 26th 2008 leading to widespread blackouts across parts of the UK. This sort of incident is much more dangerous to the task of keeping the lights on than anything reneweable energy will throw up. The sheer size of these nuclear power plants and their inherent instability is a major threat to the continuity of the electricity supply system. - That is before you even consider the safety issues.
We can cope with variable production from renewables with a variety of hi-tech, low cost, measures - and minimise the need for extra 'back up'gas power stations. These hi-tech measures include demand side management techniques which involve shaving off the peaks in peak demand (using price signals to shift demand from one period to the next), building more interconnectors to shift power around Europe and gain the benefit of systems such as storage offered by Norweigian hydro, and in the future using 'extended range' electric cars to manage the variability of renewable supplies. See previous blog about electric cars - you can shift between petrol and electricity modes in these vehicles according to the variability in renewable production using computerised price signals - the same principle which applies to demand management using smart grids and giving the National Grid more incentives to use demand management techniques.
Is the Government going to adopt these hi-tech measures in its 'electricity market reform' (EMR)? Of course not! The aim of the EMR is to cut back the renewables programme and shift the incentives to nuclear power. Far from incentives being given to encourage demand side management or energy efficiency in the electricity system, bungs will be offered to the electricity companies to build more power plant. In fact there's more than enough gas power stations coming on line to provide loads of 'back up' already. The only reason you might need all of this plant is to provide emergency supplies when nuclear power stations break down unexpectedly!