Fast neutron reactors / breeder reactors need I'm not exactly sure but something like 20% but they can use very highly enriched. Naval reactors can use very highly enriched for longer fuel service life, it's not necessary but they can and it has benefits.

The US and Russia in slightly better days were burning off their excessive amounts of stockpiled enriched uranium and plutonium in fast neutron reactors just to get rid of it as part of a mutual drawdown of stockpiles – not at all necessary but can definitely be used.

Small amounts for research reactors, medical isotope production and the like is an argument.

Those are the possible uses but it's just thinly veiled BS when a country like Iran has 60% enriched uranium for civilian power projects. The only actual reason to stockpile it like that is so you can spout nonsense about its purpose while only being a short distance away from enriching it to weapons grade.