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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Reflections on NOW
Hash Hasemianpresident@ans.org
Last month, I talked about my goal of strengthening ANS’s voice, in part by attending three conferences. I have now checked the first event off that list: the Nuclear Opportunities Workshop.
This year, NOW took another step in outgrowing its “workshop” moniker and transitioning to a full-fledged regional conference and expo. What started only a few years ago as a small gathering in Oak Ridge, Tenn., with roughly 50 attendees has skyrocketed to an event with 1,100 people in attendance in Knoxville.
NOW’s popularity reflected how busy the roughly 350 nuclear companies in Tennessee have been in recent years. There is significant work going on surrounding Gen IV reactor development and deployment, advancements in new nuclear fuels, and defense-related builds like the Uranium Processing Facility.
Douglas E. Peplow, Thomas M. Evans, John C. Wagner
Nuclear Technology | Volume 168 | Number 3 | December 2009 | Pages 785-792
MC Calculations | Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (PART 3) / Radiation Protection | doi.org/10.13182/NT09-9
Articles are hosted by Taylor and Francis Online.
Monte Carlo is quite useful for calculating specific quantities in complex transport problems. Many variance reduction strategies have been developed that accelerate Monte Carlo calculations for specific tallies. However, when trying to calculate multiple tallies or a mesh tally, users have had to accept different levels of relative uncertainty among the tallies or run separate calculations optimized for each individual tally. To address this limitation, an extension of the Consistent Adjoint Driven Importance Sampling (CADIS) method, which is used for difficult source/detector problems, has been developed to optimize several tallies or the cells of a mesh tally simultaneously. The basis for this method is the development of an importance function that represents the importance of particles to the objective of uniform Monte Carlo particle density in the desired tally regions. This method utilizes the results of a forward discrete ordinates solution, which may be based on a quick coarse-mesh calculation, to develop a forward-weighted source for the adjoint calculation. The importance map and the biased source computed from the adjoint flux are then used in the forward Monte Carlo calculation to obtain approximately uniform relative uncertainties for the desired tallies. This extension is called forward-weighted CADIS, or FW-CADIS.