Although there are a few positives, but don't plan on sticking around
Pros
Good location if you enjoy the outdoors Will support you to get additional qualifications Never going to be laid off or fired working here
Cons
The new T&Cs are poor. At least for engineers it is quite easy to find better offers in less remote locations in terms of pay and leave. There culture of "serving your time" means time spent working at Sellafield counts for a lot more than your knowledge or ability to deliver. Too many engineers don't really know anything, so it's difficult to find decent mentors. You can usually become an "expert" on a subject by reading the manual and wikipedia page. Perhaps because of this, engineering is too much like middle management, technical problems and issues are rare and infrequent, days full of paperwork, reports, and meetings. Despite this, record keeping is very poor. Hard to find information. Nuclear documentation is excellent, but often sensible conventional things that should be written down are just carried around in people's heads and you have to do some serious detectivework to answer almost any question. Too much office politics. The Sellafield slogan might as well be "play the game". I've been in entire meetings were we discussed the body language of senior executives instead of fixing or improving things. A lot of people genuinely do nothing. Although safety is meant to be the overriding priority, lack of engineering knowledge and a general assumption that we already know/do everything means that there are plenty of bits of kit lying around that will eventually hurt or kill someone. The new T&Cs were forced on new starters in 2017 despite being unfinished. Only the "Entry" level pay level is available and everyone has been stuck on that. Management seem to hate most of the staff, everybody gets lumped into the lazy and entitled Sellafield employee stereotype even though it's management that allowed this situation to happen in the first place. No real culture of improvement or innovation in most of the company. There are thinly veiled attempts such as "Dragons Den" style sessions, but these don't come up with real solutions, and the panel of judges always support stupid ideas like billing staff for using printer paper. Management often ignore good ideas, then hire consultants to tell us how to do what we already knew we should be doing. Everything is done by committee. To make any change at all, be prepared to explain anything and everything, in the simplest possible terms, again, and again, and again. It is hard to drive out of Cumbria, so be prepared for any journey to the city to be a long one. A lot of the buildings get their heating from an old steam distributions system that fails as regular as clockwork. If you're on plant then prepare to be cold. For some reason "Engineering" and "Maintenance" are two different things. It's never clear who is really responsible for what, but there seems to be a constant fight to try and make "Engineering" a bureaucracy subservient to the doers. A really reactive culture. Improvements only happen after things start going wrong, and the people put in charge of coming up with solutions and implementing them, are usually the same people who let the problem happen in the first place. There is a strange kind of inverted snobbery where people from a "graduate" background are considered second to ex-apprentices. If you're early in your career and need people to do things for you, then be prepared to lie about, or at least not mention background.
