If it makes you feel better, to put things in perspective, the planned discharge of 22TBq per year is actually a lot lower than what other countries with normally operational nuclear power plants are already doing, including Korea.

I'm not an expert in this field either and perhaps there should be a bigger discussion/education to be had if we should all be dumping so much stuff in the ocean, but IMHO if it was deemed safe when Korea discharged 211TBq into the ocean in 2020, this shouldn't change your mind either.