In 2016, researchers at the University of Oxford discovered a natural reserve of this resource in the East African Rift Valley by using traps to find zones with optimal volcanic dilution. Some hospitals have explored in-house recycling methods for this resource, which must be removed in the event of an MRI machine quench. A current auction to sell off US production facilities of this resource at the (*) Cliffside Enrichment Unit is set to close in January 2024. An earlier Stewardship Act concerning this resource stipulated the sale of that facility, part of the Federal Reserve of this resource in Amarillo, Texas, by (-5[1])2021. That sale has been delayed because this resource now faces a worldwide shortage. For 10 points, a 2020 Hawai‘i bill banned the intentional mass release of balloons filled with what resource? (10[1])■END■