Senate Bill 125 mandates the Public Service Commission (PSC) to conduct a nuclear power siting study and submit a report to the legislature within 12 months of the bill's enactment. The study will identify opportunities for nuclear power generation at existing and new sites, including advanced nuclear reactors and fusion energy technologies. The PSC may contract a third party to assist with the study and must consider a previous siting study conducted by the U.S. Department of Energy. Additionally, the bill establishes a new appropriation for the study under section 20.155 (1) (a) and creates section 196.025 (8) to outline the study's requirements.

Furthermore, the bill modifies the process for obtaining a certificate of public convenience and necessity (CPCN) for large electric generating facilities that utilize advanced nuclear reactors. It renumbers existing legal language and introduces new provisions that require the PSC to take final action on such applications within 150 days of their completion. If the PSC does not act within this timeframe, the application is automatically considered approved unless an extension is granted for good cause. This change aims to streamline the approval process for advanced nuclear projects, promoting the development of nuclear energy in Wisconsin.