2018 Annual Meeting

Presentation information

Oral presentation

VI. Health Physics and Environmental Science » Health Physics and Environmental Science

[3E05-09] Environmental Radioactivity and Dose Assessment

Wed. Mar 28, 2018 10:35 AM - 12:00 PM Room E (R1-311 -R1 Building)

Chair: Takahashi Fumiaki (JAEA)

10:50 AM - 11:05 AM

[3E06] Generation Origin of Insoluble Cs Particles Observed in Kanto District Four Days After the Fukushima Daiichi NPP Accident

*Akihide Hidaka1 (1. JAEA)

Keywords:Fukushima Daiichi Nuclear Power Plant Accident, Source Terms, Insoluble Cs Particle, Hydrogen Detonation at Unit 3, Melt Atomization, Resuspension

As for the insoluble Cs particle (A type) observed in the Kanto district on the morning of March 15, Unit 2 has been considered to be the origin of the release based on the wind direction or speed and the accident progression just before the observation. However, taking into account that the particle could have been formed by the melt atomization and is smaller than the particle (B type) originated from Unit 1, it is considered to have been generated when the hydrogen detonation occurred at the R/B of Unit 3 at 11:01, March 14. Although most of the generated Cs particles were dispersed to the Pacific Ocean because of the wind direction at that time, some of them moved to and deposited on the lower elevation of the R/B of Unit 3, could have been subsequently re-suspended and released into the environment, by the steam flow generated in the R/B due to large amount of steam generation in the containment caused by restart of the Unit 3 core cooling water injection at 2:30 of March 15 after the cooling interruption for 6 hours.