I worked in the Nuclear Power industry in Britain as a C&I Engjneer - just to declare my bias up front. As a graduate i was trained in reactor design and technology with a focus on previous disasters and why they happened so we might help avoid new ones ... or at least not repeat the old ones. Obviously what follows will be biased by my training but was accepted by many of us as fact at the time, times change, but I thought my experience might be interesting to some of you folks here discussing this:
UK has has three generations of reactors in commercial use, horrible word, i joined a nationalised industry that was then privatised to the distaste of many of us.
The first generation of gas cooled reactors, magnox, might have been half decent at producing plutonium for bombs, but that is very old news. They were mostly decommissioned or decommisioning in my time. I assume they are all shut down now. Is there a good use for old nuclear sites? Yes, new nuclear generation!
The second generation of advanced gas cool reactors (AGR) are very poor at producing plutonium, if they were designed to do so they were very badly designed, no, they are for making electricity, we didn't need any more plutonium anyway! They were design to reuse conventional plant items from the standard coal fired stations of the day, to be safe and cheap to run. They have generally been the former, not the later. Complex designs and problems have made them uneconomical in some senses, nearly wiped away by the dash for gas, however what is the true cost of generating power? Inherently safer at a reactor physics level I was taught there was no positive feedback on loss of coolant/moderator unlike Chernobyl.
So when it came time for third generation, you might hope we redesigned the complexity out of the AGR and made even safer and cheaper to run reactors designed in the UK. Nope we bought cheaper PWR "off the shelf" from USA. Yet we couldn't just install an off the shelf design and get it through UK regulations so it got modified to make it safer still and so ended up expensive. A story from the time has top brass in engineering visiting the control room at Sizewell B to reduce costs during the construction phase, and removing unneeded windows from the control room in the belief they were helping ... as contract variations they added to the cost ...
Sadly PWR arguably have the same potential for positive feedback on loss of coolant/moderator as Chernobyl, I'm not suggesting Sizewell is unsafe, but it is a shame we gave up on UK design of the only reactor design at the time, as i understand it, that had inherently safer core designs. A idealogical point perhaps but one that was felt important by the reactor physics guys that knew more than i will ever know about such things. No containment domes were built over AGRs yet one was built over Sizewell B ... just in case.
We lost the capability to design our own safer reactors, now we can't even afford to fund building other's designs it seems, I left the industry not long after completing my graduate training, dejected at the direction nuclear generation was going, and at a personal level wanting to design and build stuff not but it and install it.
