* BWR reactors use less substantial construction because pressures are much lower than PWR. Intense pressure is used to prevent the water inside a PWR from boiling. Pressure in a PWR can reach 22.064 MPa (3200 PSIA). Contrast this with the 7.6 MPa (1000–1100 psi) present in a BWR. PWR has its own set of risks, and the discussion of PWR vs BWR in the nuclear community would seem familiar to many in the tech community. cough Emacs vs Vim cough.
* Mark I reactors are Mark I for a reason. They were initial designs succeeded by Mark II, III. No one questions that we can do better because we have. We can all sit around and pontificate on the shortcomings of Mark I BWR units, but what is the solution? The solution is to pursue decommissioning and replacement with newer, safer technology.