Leaching behavior of multiphase solidified melt prepared from stainless steel and Zircaloy

ABSTRACT

Formation of metallic fuel debris is highly probable in the damaged core of the Fukushima Daiichi Nuclear Power Station. Estimating the number of radionuclides released from the fuel debris to an aqueous solution is indispensable for proper handling of fuel debris and waste management. In the present study, a simple approach is introduced to roughly evaluate the mass of elements leached from complex multiphase surfaces considering the surface-area-weighted average of the contributions of individual phases. Static leaching tests were performed under the acidic and the alkaline conditions to investigate the gap between the simplified assumption and the actual dissolution behavior. Alloy samples of a stainless steel–Zircaloy (SUS–Zry) solidified melt and two single-phase samples ((Fe,Cr)₂Zr- and Zr₂(Fe,Ni)-type phases, which comprised the surface of the SUS–Zry alloy) were used in the static leaching tests. The masses of the Fe, Cr, Ni, and Zr leached from the SUS–Zry alloy fitted with those evaluated by the surface-area-weighted approach by 1–2 orders of magnitude of precision.

KEYWORDS:

• Fuel debris
• multiphase
• leaching
• surface area
• stainless steel
• Zircaloy
• intermetallic compounds
• hydrochloric acid
• sodium hydroxide solution

Acknowledgments

The author wishes to thank the Test-conduction team of the Inspection Development Co. Ltd. for their technical support in the sample preparation, experimental setup, and analyses. The author also wishes to thank Mr. Hiromu Ambai of JAEA for his technical support in the ESCA analyses.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

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