and what about final disposal do we just let them sink and pollute a large area of ocean or what
Depends what reactor you use. The scare stories are from old first generation 1950's uranium reactors.
Thorium-based nuclear power - Wikipedia, the free encyclopedia
Quote... There is much less nuclear waste—up to two orders of magnitude less, states Moir and Teller, eliminating the need for large-scale or long-term storage; "Chinese scientists claim that hazardous waste will be a thousand times less than with uranium." The radioactivity of the resulting waste also drops down to safe levels after just a few hundred years, compared to tens of thousands of years needed for current nuclear waste to cool off... unquote.