2022 Annual Meeting

Presentation information

Oral presentation

V. Nuclear Fuel Cycle and Nuclear Materials » 502-1 Nuclear Materials, Degradation, Radiation Effects, and Related Technology

[3J09-13] Debris 1

Fri. Mar 18, 2022 2:45 PM - 4:15 PM Room J

Chair: Sosuke Kondo (Tohoku Univ.)

3:15 PM - 3:30 PM

[3J11] Investigation of re-distribution of B in SUS304-B4C alloy under high temperature steam simulating BWR severe accident

*Shinnosuke Sakuma1, Ayumi Itoh1, Shintaro Yasui1, Yoshinao Kobayashi1, Kenichi Ito2, Mutsumi Hirai2, Masato Mizokami2 (1. Tokyo Tech, 2. TEPCO HD)

Keywords:Fukushima Daiichi nuclear power station accident, BWR, Control rods, SUS304-B4C

The isothermal annealing experiment was performed with the SUS304-B4C alloy under Ar + steam atmosphere at 1100 ℃ for 1-4 h to investigate the distribution behavior of boron in the Fukushima Daiichi Nuclear Power Plant Unit 2. Metallographic analysis of the specimens after the test revealed that the boron existed as (Fe,Cr)2B intermetallic compound in the bulk and (Fe,Cr)-B-O oxide was formed on the surface due to the chemical reaction between oxygen from steam and boron diffused from the bulk, which was not expected in thermodynamics evaluation before the test and was newly observed phenomena. Consequently, this study provided new insights into the formation of boron in the fuel debris and contribution to improving the accuracy of the re-criticality evaluation.