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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Deep Space: The new frontier of radiation controls
In commercial nuclear power, there has always been a deliberate tension between the regulator and the utility owner. The regulator fundamentally exists to protect the worker, and the utility, to make a profit. It is a win-win balance.
From the U.S. nuclear industry has emerged a brilliantly successful occupational nuclear safety record—largely the result of an ALARA (as low as reasonably achievable) process that has driven exposure rates down to what only a decade ago would have been considered unthinkable. In the U.S. nuclear industry, the system has accomplished an excellent, nearly seamless process that succeeds to the benefit of both employee and utility owner.
M. Zabiégo, F. Fichot, P. Rubiolo
Nuclear Technology | Volume 154 | Number 2 | May 2006 | Pages 194-214
Technical Paper | Thermal Hydraulics | doi.org/10.13182/NT06-A3728
Articles are hosted by Taylor and Francis Online.
In the frame of Institut de Radioprotection et de Sûreté Nucléaire research programs on severe accidents in pressurized water reactors (PWRs), a new radiative heat transfer model to be used in the ICARE/CATHARE software is presented. The reactor core is considered an optically thick porous medium, and the diffusion approximation is adopted. The equivalent conductivity of the medium is determined. Its expression is carefully established to take into account the strong geometrical variations occurring in a reactor core undergoing a severe accident sequence (as observed in Three Mile Island Unit 2). After describing the theoretical basis of our approach, it is shown that the continuity of the equivalent conductivity is ensured when the geometry evolves from an array of intact cylinders to a particle bed.When compared to the more classical radiation method used in most severe accident codes, this approach better predicts the radial temperature gradient obtained by Cox in his experiment in bundle geometry. The same comparison on a PWR vessel undergoing an accidental sequence brings to the fore the impact of the radiation modeling on the degradation process: The sideward heat losses predicted by the method selected in this work are more limited, which slows the radial progression of the degradation.