Volatilization of B$_4$C control rods in Fukushima Daiichi nuclear reactors during meltdown: B–Li isotopic signatures in cesium-rich microparticles - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue J.Hazard.Mater. Année : 2022

Volatilization of B$_4$C control rods in Fukushima Daiichi nuclear reactors during meltdown: B–Li isotopic signatures in cesium-rich microparticles

Kazuki Fueda
  • Fonction : Auteur
Ryu Takami
  • Fonction : Auteur
Kenta Minomo
  • Fonction : Auteur
Kazuya Morooka
  • Fonction : Auteur
Kenji Horie
  • Fonction : Auteur
Mami Takehara
  • Fonction : Auteur
Shinya Yamasaki
  • Fonction : Auteur
Takumi Saito
  • Fonction : Auteur
Hiroyuki Shiotsu
  • Fonction : Auteur
Toshihiko Ohnuki
  • Fonction : Auteur
Gareth T.W. Law
  • Fonction : Auteur
Rodney C. Ewing
  • Fonction : Auteur
Satoshi Utsunomiya
  • Fonction : Auteur

Résumé

Boron carbide control rods remain in the fuel debris of the damaged reactors in the Fukushima Daiichi Nuclear Power Plant, potentially preventing re-criticality; however, the state and stability of the control rods remain unknown. Sensitive high-resolution ion microprobe analyses have revealed B–Li isotopic signatures in radioactive Cs-rich microparticles (CsMPs) that formed by volatilization and condensation of Si-oxides during the meltdowns. The CsMPs contain 1518–6733 mg kg–1 of 10+11B and 11.99–1213 mg kg–1 of 7Li. The 11B/10B (4.15–4.21) and 7Li/6Li (213−406) isotopic ratios are greater than natural abundances (~4.05 and ~12.5, respectively), indicating that 10B(n,α)7Li reactions occurred in B4C prior to the meltdowns. The total amount of B released with CsMPs was estimated to be 0.024–62 g, suggesting that essentially all B remains in reactor Units 2 and/or 3 and is enough to prevent re-criticality; however, the heterogeneous distribution of B needs to be considered during decommissioning.
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Dates et versions

hal-03578830 , version 1 (17-02-2022)

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Kazuki Fueda, Ryu Takami, Kenta Minomo, Kazuya Morooka, Kenji Horie, et al.. Volatilization of B$_4$C control rods in Fukushima Daiichi nuclear reactors during meltdown: B–Li isotopic signatures in cesium-rich microparticles. J.Hazard.Mater., 2022, 428, pp.128214. ⟨10.1016/j.jhazmat.2022.128214⟩. ⟨hal-03578830⟩
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