The reason they are NOT is because they cannot get planning, and they are faced with a totally open ended 'clean up charge' that a government may or may not impose on them sometime in the future.
on economic grounds, without those two issueas, they make sense.
But faced with a bunch of ale swilling bearded bunny huggers putting up CND camps in the middle of a building site, they tend to say 'not worth the risk'
Look at Huntingdon Life Sciences for how a vicious minority can wreck a company for no good reason other than religious hatred?
Then there is teh vexed 'decommissioning cost' issue. Its totally biased against nuclear power. No one expects the fossil fuel plant to be charged for the cost of removing a few billion tons of CO2 from the environment..but a couple of billion levy for a few hundred tons of uranium, Hey why not?