Past exam of the short options paper shared by Prelims and Parts A and B of the physics course of the University of Oxford / 2012 / S4 / 3 / b / Solution

The judgement depends on the objectives and the replacement system, rather than following from a single technological fact. In the 2012 context, Germany had decided after Fukushima to accelerate its planned nuclear exit, with a timetable then extending to 2022. The contemporary official statement presented this as a reassessment of residual risk and a transition to efficiency and renewable supply.^[ref]

There is a serious climate opportunity cost if low-operational-carbon nuclear generation is replaced by unabated fossil generation. For example, replacing an illustrative $100\mathrm{TWh}\mathrm{yea}{\mathrm{r}}^{-1}$ with generation emitting $400$ or $900\mathrm{g}\mathrm{C}{\mathrm{O}}_2\mathrm{kW}{\mathrm{h}}^{-1}$ adds $40$ or $90$ million tonnes of carbon dioxide annually. Replacing that energy by wind at capacity factor $0.30$ would require about $38\mathrm{GW}$ of nameplate capacity, plus an adequate reliability plan; equal annual energy is not equal firm capacity.

Against continued operation must be weighed accident consequences, waste management, ageing, public preferences and the costs and feasibility of alternatives. Germany's specific risk assessment cannot be inferred solely from the different geography of Fukushima. A fast exit without credible low-carbon replacement can conflict with emissions goals; an exit supported by efficiency, infrastructure and low-carbon alternatives can pursue other legitimate objectives. Calling the decision intrinsically rational or irrational without those comparisons is not a technical conclusion. This answer evaluates the choice as posed in 2012, rather than importing later events as foreknowledge.