U.S. DOE SEVERE ACCIDENT RESEARCH FOLLOWING THE FUKUSHIMA DAIICHI ACCIDENTS

摘要

The Department of Energy (DOE) has played a major role in the US response to the events at Fukushima Daiichi. During the first several weeks following the accident, US assistance efforts were guided by results from a significant and diverse set of analyses. In the months that followed, a coordinated analysis activity aimed at gaining a more thorough understanding of the accident sequence was completed using laboratory-developed system-level and best-estimate accident analysis codes, while a parallel analysis was conducted by industry. A comparison of predictions for Unit 1 from these two studies indicated significant differences between MAAP and MELCOR results for key plant parameters, such as in-core hydrogen production. On that basis, a cross-walk was completed to determine the key modeling variations that led to these differences. In parallel with these activities, it became clear that there was a need to perform a technology gap evaluation on accident tolerant components and severe accident analysis methodologies with the goal of identifying any data and/or knowledge gaps that may exist, given the current state of LWR severe accident research, and augmented by insights from Fukushima. In addition, there is growing international recognition that data from Fukushima could significantly reduce uncertainties related to severe accident progression, particularly for BWRs. On these bases, a group of US experts in LWR safety and plant operations was convened by the DOE office of Nuclear Energy (DOE-NE) to complete technology gap analysis and Fukushima forensics data identification activities. Results from these activities were used as the basis for refining DOE-NE's severe accident Research and Development (R&D) plan. This paper provides a high-level review of DOE sponsored R&D efforts in these areas, including planned activities on accident tolerant components and accident analysis methods.