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The spark of the Super: Teller–Ulam and the birth of the H-bomb—rivalry, credit, and legacy at 75 years
In early 1951, Los Alamos scientists Edward Teller and Stanislaw Ulam devised a breakthrough that would lead to the hydrogen bomb [1]. Their design gave the United States an initial advantage in the Cold War, though comparable progress was soon achieved independently in the Soviet Union and the United Kingdom.
Nikolas G. Nelson, Son N. Quang, Nicholas R. Brown, G. Ivan Maldonado
Fusion Science and Technology | Volume 82 | Number 1 | January-February 2026 | Pages 299-310
Research Article | doi.org/10.1080/15361055.2025.2478542
Articles are hosted by Taylor and Francis Online.
The shutdown dose rate (SDR) is critical for developing a plan for safe operation, establishing a maintenance scheme, and guiding potential design changes in a fusion energy system. This study identifies lithium ceramic blanket materials that produce lower dose rates compared to the leading dual-coolant lead-lithium breeder blanket concept. The aim is to find an optimal balance between maintaining a manageable SDR and achieving improved tritium recovery and thermal performance with ceramic blankets. This study was conducted on a 22.5-deg symmetric sector model of the Fusion Energy System Studies–Fusion Nuclear Science Facility (FESS-FNSF) and presents effective dose calculations for key components of the reactor as a result of using various blanket materials. The deuterium-tritium operational phase of the FESS-FNSF will last approximately 2.75 years and be used to define the neutron source. A Rigorous 2-Step workflow was used in OpenMC to calculate SDRs after shutdown, 1 day, 1 year, and 100 years for several lithium ceramic breeders. Across all time intervals, the PbLi blanket consistently exhibited the lowest SDR in the plasma region, though it contributed more to SDR in the outboard and inboard regions. The LiAlO2 blanket produced the highest SDR throughout, while Li4SiO4, Li2TiO3, and Li8ZrO6 provided the lowest SDRs among the ceramics. Regarding the effect of the beryllium multiplier, the pure Be multiplier led to lower SDRs, followed by Be12Ti, and finally Be12V. For all blanket materials tested at these different time periods, the SDR was found to exceed the limit of 2 × 103 μSv/h, thus suggesting the need for remote or robotic maintenance.