AstraZeneca is doing this study to learn more about durvalumab and bevacizumab given together after the TARE Y90 procedure in participants with HCC, and also to better understand HCC and associated health problems. Patients with unresectable locoregional HCC are treated with TARE Y90 as recommended by treatment guidelines developed by the National Comprehensive Cancer Network (NCCN). Durvalumab is a type of anticancer drug called immunotherapy that targets cancer cells by blocking the signal that prevents the immune system from seeing the cancer cell. Your immune system can then attack and kill the cancer cells.