Here in the States, all nuclear power plants are required to put a certain amount of the revenue for each kWh sold into a decommissioning fund. I've heard it comes to around a penny per kWh (which isn't a large increase in power rates, by any means).
The thing about nuclear power plants is they produce epically large amounts of power, over a long period of time, and the fuel costs are close to zero on a per-kWh basis. So, even though a plant might cost Billions to build, and another Billion or two to decomission, it's still cost effective.
Here in the States, one of the utilities called The Southern Company is building a new two-reactor NPP at the Vogtle Power Station site. It's estimated to cost $14Bn. Nuclear plants typically seem to get cost overruns, and this is a first-of-it's kind design (well, first in the US anyhow; the AP-1000 reactor). So, let's say it runs to $18Bn and another $2Bn for decommissioning and fuel disposal, for $20Bn total cost (maybe it'll be a little more, maybe a little less; you can argue with the accuracy of my numbers, but this should get us to a reasonable approximation of the actual figures within say 5 or 10%).
The AP-1000 is rated at 1117MW per reactor output (in the future, this may be able to be retrofit to higher output; that has commonly happened at other NPP's, but we'll assume constant power output over the life of the plant).
So, assuming a 60 year life for the reactors and 90% Capacity Factor, how many kWh would each reactor potentially be able to generate and sell?
1117MW * 1000 KW per MW * 24 hours per day * 365.25 days per year * 60 years * .9 capacity factor = 528,747,588,000 kWh.
That is a LOT of kiloWatt-hours. So, assuming a market price of around 5 cents per kiloWatt-hours, how much total revenue is that?
528,747,588,000 * .05 = $26,437,379,400
That's $6Bn per reactor of gross profit. Of course, there's fuel costs, insurance costs, operation and maintenance costs, which could really add up to a few Bn (particularly if there's any very expensive maintenance that has to be done in the future, such as being faced by San Onofre or Crystal River nuclear plants).
Still, that's affordable energy - much more so than solar power or wind.