It needs a custom model rather than being an iron rod.

What I'm thinking is maybe a glass rod with iron bars. Similiar in visual to a buildcraft pipe for the shell. Then inside a graphite rod with a noise texture.

After talking to a few people we might just replace the entire rod system. Every person I asked could not recall using the system. As the reactors were rather stable and rarely did much damage when they failed. As well rods had limited usage and looked bad.

My thought is to replace it with a system mirroring real life. Either using gravity driven rods or a block containing the rod. This would make it easier to use and would look much nicer.