Computational Tools for Solving Environmental Issues for Today’s Nuclear Power Plants

摘要

Computational methods have changed and improved greatly since the installation of a flock of nuclear power plants three decades ago. Computational methods serve to better ensure compliance to the Nuclear Regulatory Commission’s regulations as regards environmental issues that may affect the safe and efficient operation of nuclear power plants. Today, existing guidance leaves it up to licensees to determine how they intend to meet the intentions of NRC guidance. The consistent approach for many licensees is generally to determine the robustness and use of newer tools in the form of computer programs, which address NRC guidance and provide a reasonable assessment of assumed conditions. This paper addresses new computational tools that are being proposed to address needed advances. The focus will be on Areal Locations of Hazardous Atmospheres, more commonly known as ALOHA, on computational fluid dynamics (CFD), and on other computational methods that can be used separately or in combination to solve the multiphysical (and thus, multidisciplinary) problems of regulatory compliance. The use of tools from industry applications, other than those suggested in the NRC guidelines, are being employed to address new approaches for hazards analysis. A technological approach for adapting these new tools, and their ability to provide an estimate of hazards, is presented. The circumstances of 9-11 and other terrorist activities have taken away information for public use, thus creating a vacuum of inconsistency throughout the industry. Problems such as toxic plume dispersion for evaluation of control room habitability; safe stand-off distance to plant structures due to drifting explosive vapor clouds; and degradation of nearby facilities, vegetation and natural resources due to contaminated drifts, require a multi-disciplined--and sometimes three-dimensionally--accurate solution. A more matured technological approach is being suggested to provide a reasonable approach for estimating hazards and the effects of assumptions relating to the safety of the public and plant. The following discussion of case studies shows the effectiveness of these computational tools in making regulatory compliance demonstrations. An overview of these tools’ limitations, and their combined capabilities, encourages us to consider how approaches can be merged for reasonable solutions. A presentation of how each tool can be applied individually, or in combination, to evaluate environmental and hazardous safety issues is also a part of this discussion.