A new perspective into molten corium concrete interaction for interpreting Fukushima Dai-Ichi terrace-shaped debris.

This paper compares open-source volcanic lava images with official TEPCO videos and reports. The fuel debris formation at Fukushima Dai-Ichi Nuclear Power Station (1F) Unit 1 shows similarities to natural lava flows at various volcanoes, including submarine eruptions and pillow lava. Based on evidence found in 1F debris images, the author suggests the unconventional interaction between molten corium and concrete (MCCI). The MCCI could have started in upper pedestal region due to an RPV failure above the RPV skirt, which is higher than usually considered. Additional volume, which cannot be explained now, was explained in the study as mass of MCCI products created in the upper areas of pedestal where hot corium first reacted with concrete. This unconventional MCCI would have brought enough melt to reach the observed terrace-shaped debris height. The current paper attempts to establish the fact that the natural mechanism of 1F terrace-shaped debris formation is easily identifiable through a multidisciplinary approach, which opens the scientific communities of volcanologists and materials scientists to a collaboration.