ASP Isotopes Inc. (ASPI) experienced a wild ride on Tuesday, with its shares initially soaring more than 35% in pre-market trading on news of a deal with Bill Gates-backed TerraPower to build a facility to produce High Assay Low-Enriched Uranium (HALEU) for next-generation nuclear reactors. However, the euphoria was short-lived as the stock plunged 5.51% in after-hours trading.

The agreement, announced early Tuesday, saw ASPI sign a term sheet with TerraPower to construct a uranium enrichment facility capable of producing HALEU, a critical fuel source for TerraPower's planned $4 billion Natrium nuclear reactor project in Wyoming. Under the deal, TerraPower will provide funding for the facility's construction, and the companies plan to sign a long-term supply agreement for all HALEU produced over a 10-year period.

While ASPI hailed the deal as a major milestone, citing its potential to deploy enrichment technologies at significantly lower capital costs and faster construction times compared to traditional centrifuge processes, the lack of financial details disclosed may have raised concerns among some investors. Additionally, the potential proliferation risks associated with HALEU production and uncertainty surrounding the facility's location, which is expected to be in South Africa according to reports, could have contributed to the after-hours sell-off.