Here is my design for 6 chamber dual thorium reactor. I prefer dual thorium to quadruple due to copper cost. I am currently looking for neat plutonium reactors.
http://www.talonfiremage.pwp.blueyonder.co.uk/v3/reactorplan…zgetjtrli97uv40
My design focus more on the output then on efficiency. Why ? Because I strip mine with a frame machine and have more uranium that i can use. (the casing plate is not needed, but makes the use of pipes easier to fill the reactor)