• Summary of planning lecture at 2016 Fall Meeting

    Posted on March 31st, 2017 Takashi Takata No comments

    Thu. Sep 8, 2016 1:00 PM – 2:30 PM

    Room L (Kumume City Plaza – Assembly Room 2)

    ”Numerical Simulations for External Hazard Evaluation”

    Chair person: Akemi Nishida (JAEA)

    Evaluation of various external hazards is required while conducting inspections related to compliance of the new regulatory standards specified by the Nuclear Regulation Authority. However, since hazardous factors subject to evaluation are massive in scale with a lot of uncertainties (e.g. frequency and intensity of incidences), it is difficult to evaluate them by conducting regular testing. Generally, numerical simulations are used for this kind of evaluation, which is considered particularly effective for cases addressed in this session (excluding evaluation of earthquakes, which was done in a planning session in 2013). There remain several issues in simulations, including selection of an appropriate model and setting boundary conditions. It is not an easy task to get results that might provide any satisfactory explanation (adequacy).
    In this session titled “Numerical simulations for evaluation of external hazards,” a series of lectures were given by experts for the results of simulating three phenomena, such as tsunami, tornado, and aircraft collision. The purpose is to show the appropriate use of numerical simulations for evaluating external hazards and to address issues related to enhancing the accuracy of simulation in the future. The number of audiences in this session was 41.

    (1) Evaluation of Fluid Force Acted on Structures by Using Multi-Scale Particle Method

    Speaker: Mitsuteru Asai (Kyushu Univ.)
    Presesntation material (in Japanese)

    In analyzing the tsunami force, there are many unknown factors in the mechanism of a tsunami acting on structures, and therefore, no clear design standards are established. This lecture presented an example of evaluating tsunami force affecting tsunami evacuation buildings and bridges, etc. using a multi-scale analysis tool based on the three-dimensional particle method.

    (2) Current Status on Numerical Simulation Methods to Evaluate Tornado Missile Hazard

    Speaker: Yuzuru Eguchi (CRIEPI)
    Presesntation material (in Japanese)

    The design speed of tornado-generated missiles is indicated in NUREG1.76 of the NRC in the U.S., and the “Assessment guide for tornado effect on nuclear power plants” in Japan. This lecture presented how numerical simulations are used in these guides, and compared the results of numerical simulations with those of an evaluation method using the Fujita model, which is closer to the actual tornado velocity field.

    (3) Aircraft Impact Assessment for Nuclear Power Plant Design

    Speaker: Haruji Tsubota (JAEA)
    Presesntation material (in Japanese)

    The nuclear power plant is required to maintain structural safety not only for natural disasters like earthquakes and tsunamis, but it must also be able to withstand possible aircraft collisions. In addressing the design of impact resistance for nuclear power plants against aircraft collisions, this lecture first reported the overview of the impact tests using an aircraft (F-4 Phantom), and then presented the latest trend of research for simulation analysis of a large civilian aircraft colliding into the nuclear power plant.

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