Nuclear likes to produce a slow, steady, constant output. If there aren't good on demand fill sources the alternative (point 5) either involves batteries (or another reservoir of some-kind, EG reverse pump hydro; which BTW exists near some river dams) OR a variable consumer. A consumer that doesn't mind getting suddenly cut without warning. This might be an electrolysis process for separating water in to hydrogen and oxygen for industrial applications / chemical fuel production, or it could be some other similar process that might benefit from a stable run cycle but isn't catastrophically affected by loss of power.