Instead of doubting, and thinking based belief, maybe you should verify ?

https://en.wikipedia.org/wiki/Life-cycle_greenhouse_gas_emis...

The wikpedia source give a breakdown of how the CO2 per kwh is calculated for a Sweden nuclear plant, it take everything in account, the building, nuclear fuel processing and storage, and even the electricity distribution to the grid.

Then, no sarcophagus are built at the end of the nplant timelife, they built ont for chernobyl, that all.