How much energy would the reaction produce in a week if kept operational?

And about how much of Europe could be powered by JET?

This question deals with a hypothetical scenario. JET is an experiment and its aim is not to produce electricity. JET can operate close to breakeven, but even in these conditions the electricity used to maintain the plasma would by far exceed the electricity that could be generated. ITER – JETs international successor – will generate ten times more fusion power than the power injected into the plasma to sustain the fusion process. Also ITER will be an experiment and not generate any electricity. Although there is a net amplification of the power by the ITER plasma, the electricity drawn from the grid will be higher than ITER could potentially generate from the fusion heat if it would be equipped with suitable blankets and turbines. DEMO will be the first device that will generate electricity. This demonstration reactor will generate in the order of 100 MW more electricity from fusion than what is extracted from the grid. The future commercial fusion power stations are expected to generate a much higher level of power.