What are the differences between the BWR Model 3 and the Model 4 if they are both are in Mark 1 (torus) reactor containment buildings.
Quad Cities (model 3)
Cooper (model 4)
The difference is WAY beyond skin deep.
The oldest BWR in the US is Oyster Creek a BWR/2. NMP Unit 1 is also a BWR/2. BWR/2s have Mark I Drywells, like BWR/3s and BWR/4s.
BWR/2s have five recirc loops - thats a lot of RPV connected piping and a lot of LOCA risk.
BWR/3s have two (variable speed pump) recirc loops. Some BWR/3s have Isolation Condensers (Dresden), some have RCIC (Quad). BWR/3s have HPCI.
RHR and Core Spray in TWO safety divisions.
They were built around a max of 750 Mwe. (uprated since)
BWR/3s trigger ADS Timers at RPV L2.
By comparison, they have lower power densities than BWR/4s.
The bigger, higher power density BWR/4s were built at over 1000 Mwe.
All discussed so far have Mark I Drywell, Nitrogen inerted containments. BWR/4s have RCIC and HPCI.
Redundant Core Spray Loops, and RHR LPCI in TWO safety divisions.
BWR/4s trigger ADS Timers at RPV L1.
BWR/5s were built with two recirc loops with two speed Recirc Pumps and FCVs (some now have ASDs). They all live in Mark II Drywells. They are also Nitrogen inerted.
BWR/5s have HPCS, LPCS, and RHR, THREE safety divisions.
BWR/6s were built with two recirc loops with two speed Recirc Pumps and FCVs (some now have ASDs). They all live in Mark III Drywells. Not Inert. They have Hydrogen Recombiners and Ignitors.
BWR/6s have HPCS, LPCS, and RHR, THREE safety divisions. Some BWR/6s were built with GANG rod drive capability. Some have a compact Main Control Room (Clinton, River Bend).
BWR/6s do not have a Rod Worth Minimizer, they have a Rod Pattern Controller.
You asked.