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NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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Orlando, FL|Renaissance Orlando at SeaWorld
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Nuclear new build procurement considerations
It may seem counterintuitive, but the best time to enhance the ability to support operations and maintenance for a new plant is before construction starts. This is one of many lessons learned by the currently operating nuclear fleet. As construction and startup of many nuclear facilities was completed, it quickly became evident that the ability to efficiently support operations and maintenance was limited. Most of the information necessary to establish and manage procurement of spare and replacement items, maintenance, and configuration of the facilities was unavailable and had to be gathered on a case-by-case, “on-demand” basis. Absence of necessary information and the associated challenges resulted in the need for staff augmentation and multiyear-long projects to develop equipment bills of material and maintenance programs and to perform technical evaluations for the huge quantities of spare and replacement items being requested.
Chenghui Wan, Wenchang Dong, Lin Guo, Jiahe Bai
Nuclear Science and Engineering | Volume 197 | Number 7 | July 2023 | Pages 1454-1466
Technical Paper | doi.org/10.1080/00295639.2022.2158704
Articles are hosted by Taylor and Francis Online.
The “two-step” scheme based on assembly homogenization is widely applied in simulations for pressurized water reactor (PWR) cores in which the few-group constants of the fuel assembly are generated with the single-assembly simulation. However, the reflective boundary condition adopted in the single-assembly simulation can’t characterize the real environment in the core, especially the strong heterogeneity between the neighboring assemblies. In order to consider the environmental effects on the homogenized few-group constants, a rehomogenization method is proposed. In this method, the heterogeneous neutron spectral of single-assembly model of the reflective boundary condition is corrected with the homogeneous neutron spectral of the real core environment. Through definition and precalculation of the rehomogenization factors for few-group constants during the fuel assembly simulation, corresponding corrected constants can be recomputed during the core simulation to consider the environmental effects. This method has been implemented in our home-developed code Bamboo-C. For method verification, both the heavy reflector PWR EPR1750 and the baffle reflector PWR HPR1000 have been simulated. It can be observed that the biases of the eigenvalues can be notably reduced with the proposed rehomogenization method. The assembly-averaged powers of the peripheral fuel assemblies were also notably reduced, especially for the EPR1750, which indicates that the environmental effects can be appropriately solved with the rehomogenization method.