A fusion rector does not have control rods. It has a magnetic containment field around a plasma which is, something like 10x hotter than the sun. if you put a control rod in there it would instantly vaporize.
At the risk of being pedantic, if this is the LLNL NIF, then it's ICF, not MCF, though putting a graphite rod at the heart of a laser-driven thermonuclear event probably looks about the same either way.
