[1H05-07] Dosimetry 2

[1H07] Evaluation of a Gamma-ray Flash coinciding with a Lightning Discharge during Winter Thunderstorms

*Yuuki Wada^1,2, Teruaki Enoto³, Kazuhiro Nakazawa⁴, Yoshihiro Furuta⁵, Takayuki Yuasa, Yoshitaka Nakamura⁶, Takeshi Morimoto⁷, Takahiro Matsumoto¹, Kazuo Makishima^1,2, Harufumi Tsuchiya⁵ (1. Graduate School of Science, The University of Tokyo, 2. RIKEN, 3. Kyoto University, 4. Nagoya University, 5. JAEA, 6. Kobe City College of Technology, 7. Kindai University)

Keywords:monitoring post, lightning discharge, gamma-ray flash

Terrestrial gamma-ray flashes, lightning-associated submillisecond emissions, have been detected by both airborne/spaceborne and on-ground detectors. Monitoring posts of nuclear power plants located along Sea of Japan also observe increases in radiation doses associated with lightning discharges during wintertime thunderstorms. We analysed a dose increase detected by ionization chambers at Kashiwazaki-Kariwa nuclear power plant in November 2017. Combining results from our independent radiation measurements and Monte Carlo simulations, we confirmed that the dose increase observed by monitoring posts originates from a downward-directed terrestrial gamma-ray flash provoked above the power plant.