Now, see, here we go. I didn’t want to go there - but yeah, I do prefer the Circle-Bar-W units. (Full disclosure - that’s a local company to me and some family have been involved in the business). The construction cost advantage does go to GE.
However, I know of at least one GE plant that had a fuel pin split and lost a couple or three pellets in the stream. That added millions to the costs on their next outage. I realized real fast why there is a bio shield around the turbine floor.
I've worked at both types units on the turbine systems (full disclosure, I was with GE, but that was almost 10 years ago now). There are advantages to both systems, and the comparisons are not as simple as PWR=good since the steam is clean and BWR=bad since the steam is hot.
Doing turbine controls, I learned real quick that the turbine control valves are critical to the reactor pressure control in a BWR. I eventually grew to like the BWR's more since the systems were more simple (I've always been a fan of the KISS principle). A BWR can use the turbine to control bubbling in the reactor to help with reactor control making it a very responsive tool to slow down the reaction if necessary (I know little about reactor control beyond that, I was only a turbine guy).
The PWR system is slower to respond to changes given the thermal lag between the primary and secondary secondary loops. I remember seeing a training video about a PWR unit that got into control stability problems in the mid atlantic states area about 1990 when the cooling system intake screens became clogged with kelp. The unit somehow began cycling wildly between high and low power because of that steam generator thermal lag. I don't remember much more than that, so the details might not be 100% correct.
Another reason I preferred a BWR was nearly every PWR I went to had a leak in the steam generator and the turbine areas had RCA's spread all over the place where you had to dress in and out all the time. The BWR was simple...dress in once when you enter the turbine area and out once when you leave!
Don't get me wrong, I am not totally against "Circle Bar W", and I am not looking to start a great debate either. But I have to root for my team! I was involved in some post startup turbine-generator vibration issues on Kashiwazaki-6 at one time (never went there, but did analysis on data while in the states). For that reason, I am very interested in what is now going on....
I work for the circlebarw ranch. In fact, I got roped in on the AP1000 design team temporarily. I have worked at at least one of each of the designs now operating in the US. I really liked the idea of the old B&W reactors with the once through steam generators producing superheated steam, but they have not really turned out as efficient as hoped. The most efficient nuke plants in the world are the Westinghouse 4 loop plants with a GE turbine.