Oak Ridge National Laboratory is expanding isotope production in separate projects, but its new Stable Isotope Production and Research Center (SIPRC) is not a plutonium-238 facility. NASA’s deep-space radioisotope power systems depend on a distinct, multi-laboratory Pu-238 supply chain. SIPRC is intended to increase U.S. production of stable isotopes; a separate planned ORNL facility will handle radioactive isotopes.
What the new center is designed to do
ORNL reported in March 2026 that SIPRC was under construction. Its planned equipment combines two approaches to stable-isotope enrichment, serving different production needs:
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- Gas centrifuge: Planned for the center’s first half, this equipment is suited to producing larger quantities.
- Electromagnetic separator: Planned for the second half, it can enrich a wider range of isotopes, generally at lower quantities.
The center is also intended to support research into enrichment gases and rebuild or extend technical knowledge in stable-isotope production. The United States’ stable-isotope production at what is now Y-12 ended in 1998, according to ORNL. SIPRC is part of a renewed capacity effort, not a spacecraft-fuel plant.
How SIPRC differs from Oak Ridge’s radioactive-isotope projects
“Isotope production” covers materials with different properties and uses. Stable isotopes do not undergo radioactive decay; Pu-238 is radioactive. ORNL’s facilities and projects therefore should not be treated as interchangeable.
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| Project | Material and approach | Purpose and status reported |
|---|---|---|
| Stable Isotope Production and Research Center (SIPRC) | Stable isotopes; planned gas centrifuge for bulk output and electromagnetic separation for a wider range at lower quantities. | Stable-isotope production and research. Under construction in March 2026. |
| Radioisotope Processing Facility | Radioactive-isotope handling and processing. | ORNL described a planned facility of approximately 90,000 square feet, with operations planned by 2039. It is intended to help meet demand for more than 20 radioisotopes. |
| Stable Isotope Production Facility | A separate facility that produces xenon-129. | ORNL reported it completed in 2025; it is distinct from SIPRC. |
These dates describe the reported status and plans; they do not mean the new SIPRC or Radioisotope Processing Facility is already operating.
How Pu-238 becomes power for deep-space spacecraft
Radioisotope power systems use heat from radioactive decay and convert it into electricity for spacecraft instruments and systems. Pu-238 is the heat source in this application, but producing the isotope is only one stage in making a working power system.
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- Target irradiation: Neptunium-237 targets are irradiated in a reactor. NASA’s FY2025 budget justification describes INL supplying neptunium-237 and irradiating targets in the Advanced Test Reactor; ORNL’s account describes irradiation in the High Flux Isotope Reactor (HFIR).
- Processing at ORNL: ORNL chemically processes the irradiated material and produces plutonium oxide.
- Fuel fabrication at Los Alamos: The oxide goes to Los Alamos National Laboratory (LANL), which manages inventory and makes fuel clads.
- Power-system integration at Idaho: Idaho National Laboratory (INL) integrates the fuel clads with generator systems. ORNL’s 2023 account describes the completed radioisotope thermoelectric generator (RTG) being sent to Kennedy Space Center.
The division of work matters: ORNL contributes Pu-238 oxide, but it does not alone manufacture and deliver a finished spacecraft generator.
What production figures do—and do not—show
ORNL reported shipping 550 grams of Pu-238 oxide in June 2023, describing it as a production-quantity shipment. NASA’s FY2025 Congressional Justification, published in 2024, described production at approximately 700 grams per year during its reporting period and a planned ramp to 1.5 kilograms annually by 2026. The 1.5-kilogram figure was a goal, not confirmation that the rate was achieved. As of October 2, 2026, the cited reports do not establish whether that target was met.
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ORNL and the Department of Energy’s isotope program support applications across medicine, industry, research and national security as well as space missions. SIPRC’s stable-isotope capability and the planned Radioisotope Processing Facility address different parts of that broader portfolio. Their expansion should not be read as evidence that every isotope needed for every application—including NASA’s Pu-238—is made in the new center.
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