The document summarizes long-term stewardship activities at the Center for Energy and Environmental Research site in Puerto Rico. The site consists of four areas totaling 181 acres. Major long-term stewardship activities include surveillance and inspections. Cleanup has been completed at all areas except the Boiling Nuclear Superheat Research Reactor site, where radioactive materials remain entombed. Long-term stewardship is expected to continue in perpetuity at this site at an estimated annual cost of $25,000 and will involve restrictions, monitoring, and record keeping to protect human health and the environment.