I don’t think so. The side reactions that give off neutrons are indeed rare. But once you scale up to MW its still a lot. Also the true cool down time will depend on other materials used. Neutron activation over days, weeks and years will not be insignificant. It is of course something that is reasonably easy to deal with, given proper materiel choices. Remember that we are talking about moles of neutrons here, they all get absorbed somewhere.
