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The human factor in licensing and operating the next generation of nuclear plants
As human factors specialists working at the intersection of human performance and nuclear operations, we are witnessing one of the nuclear sector’s most significant transitions in decades. The emergence of small modular reactors, microreactors, and other advanced designs is reshaping the industry’s landscape. Digital instrumentation and controls, passive safety systems, and increased automation are creating opportunities for greater safety margins and more flexible operation. These same features also fundamentally redefine what it means to “operate” a nuclear plant. Interactions among human roles, automation, and passive systems shape how people maintain awareness, exercise judgment, and intervene when necessary. These developments affect both operational realities and the regulatory foundations on which nuclear safety is built.
E. F. Mitenkova, N. V. Novikov, A. I. Blokhin
Nuclear Technology | Volume 183 | Number 3 | September 2013 | Pages 446-454
Technical Paper | Fission Reactors | doi.org/10.13182/NT13-A19432
Articles are hosted by Taylor and Francis Online.
Different uranium-plutonium fuel compositions are considered for sodium fast reactors of the next generation. Considerable discrepancies in axial and radial neutron spectra for hybrid reactor systems compared to uranium oxide fuel cores increase uncertainties in the key calculated neutronic characteristics of hybrid systems. The calculation results of a BFS-62-3A critical assembly considered as a full-scale model of BN-600 hybrid core with steel reflector specify quite different spectra in local areas. In such systems the MCNP5 calculations demonstrate a noticeable sensitivity of the key neutronic characteristics (effective multiplication factor keff, spectral indices) to nuclear data libraries and extra steel such as dowels placed in the core. Uncertainties in the location of stainless steel dowels and in their quantity cause uncertainties in the fuel-to-steel mass ratio in the core. For 235U, 238U, and 239Pu, the calculated radial fission rate distributions against the reconstructed ones are analyzed. A comparative analysis of spectral indices, neutron spectra, and radial fission rate distributions is performed using nuclear data libraries generated from ENDF/B-VII.0, JEFF-3.1.1, JENDL-3.3, and BROND-3 for Fe and Cr isotopes. When performing analysis of the fission-rate sensitivity to the presence of plutonium in fuel, 239Pu is replaced by 235U in local areas containing plutonium. For radial fission rate distributions, peak discrepancies may be due to possible underestimation of some features of experimental data processing and reconstruction methods (Westcott factors, temperature dependence, local core features). A more-sophisticated impact analysis of spatially different neutron spectra on neutron characteristics of the core is also required. To confirm the results of BFS-62-3A analysis, radial fission-rate distributions are calculated for BFS-62-4 with UO2 blanket instead of steel reflector.
