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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Chris Wagner: The role of Eden Radioisotopes in the future of nuclear medicine
Chris Wagner has more than 40 years of experience in nuclear medicine, beginning as a clinical practitioner before moving into leadership roles at companies like Mallinckrodt (now Curium) and Nordion. His knowledge of both the clinical and the manufacturing sides of nuclear medicine laid the groundwork for helping to found Eden Radioisotopes, a start-up venture that intends to make diagnostic and therapeutic raw material medical isotopes like molybdenum-99 and lutetium-177.
Jeffery D. Densmore, Edward W. Larsen
Nuclear Science and Engineering | Volume 146 | Number 2 | February 2004 | Pages 121-140
Technical Paper | doi.org/10.13182/NSE04-A2398
Articles are hosted by Taylor and Francis Online.
A new variational variance reduction (VVR) technique is developed for improving the efficiency of Monte Carlo multigroup nuclear reactor eigenvalue and eigenfunction calculations. The VVR method employs a variational functional, which requires detailed estimates of both the forward and adjoint fluxes. The direct functional, employed in standard Monte Carlo calculations, requires only limited information concerning the forward flux. The variational functional requires global information about the forward and adjoint fluxes and hence is more expensive to evaluate but is more accurate than the direct functional. In calculations, this increased accuracy outweighs the extra expense, resulting in a more efficient Monte Carlo simulation. In our work, we evaluate the variational functional using Monte Carlo-calculated forward flux estimates and deterministically calculated adjoint flux estimates. Also, we represent the adjoint flux as a low-order polynomial in space and angle, which is accurate for diffusive systems. (In such systems, which are common in reactor analysis problems, the angular flux is locally nearly linear in space and angle.) Using this adjoint representation, we develop specific VVR methods for eigenvalue problems, in which an estimate of the eigenvalue k in a criticality calculation is desired, and eigenfunction problems, in which an estimate of a detector response due to a fission neutron source during a criticality calculation is desired. The resulting VVR method is very efficient for the problems of interest. With a set of example problems, we demonstrate the increased efficiency of the VVR method over standard Monte Carlo.