u/MillieSievert

OK so I was having a thought the other night about the control rod design with their graphite displacers. We all know that the graphite displacers were designed to displace the water in the channels to increase reactivity when rods were withdrawn.

My question is what prevented them from having the control rods in "dry channels" so when the rods were withdrawn there would be no water in their place to absorb nuetrons thus negating the need for the displacers? Could they have gas cooled those channels to prevent the rods from melting or is there another obvious reason why this wouldnt work?