If by "available" you mean that there's a standard. There may be PHY designs that exist but they're not available for purchase, probably because there's no identifiable market. Any potential customer who for some reason wanted to build an AP1000 reactor unit for their datacenter and a second unit for that datacenter's PHYs would need to design their own networking equipment. Which might use 40G but at this point it's questionable — that's the sort of slow equipment you might see in a rack-scale on-premises installation.