 The purpose of this study is to identify maximum tolerated dose MTD, that is, the highest dose of the study drug nivolumab that does not cause unacceptable side effects, for combination treatment of nivolumab and yttrium Y 90 glass microspheres Y-90. Also, to evaluate the efficacy the effect of drug on your tumor and the tolerability the effect of the drug on your body of nivolumab, when given with standard of care Y-90 Therasphere. Nivolumab is currently Food and Drug Administration FDA approved for other cancers, but has not yet been investigated in advanced or refractory hepatocellular carcinoma. Nivolumab is an antibody a human protein that sticks to a part of the tumor andor immune cells designed to allow the bodys immune system to work against tumor cells. Y-90 is currently FDA approved for the treatment of hepatocellular carcinomas, but has not yet been investigated in combination with nivolumab for this disease. 