[3A08-12] 1F metal waste recycling

3:30 PM - 3:45 PM JST(6:30 AM - 6:45 AM UTC)

[3A11] Research and Development on Volume Reduction and Recycling of Radioactive Metal Waste(4) Group Classification and Thermodynamic Equilibrium Calculation for Establishing Radionuclide Transfer Ratios in Melting Decontamination

*Mitsuki Amano¹, Takahiro KIKUCHI¹, Eriko IRISAWA¹, Mitsuru SAMBONGI², Azusa ITO², Yoshinao KOBAYASHI³ (1. JGC, 2. JAEA, 3. Science Tokyo)

Keywords:

Fukushima Daiichi NPS,melting decontamination,thermodynamic equilibrium calculation,transfer ratio

Melting decontamination (melt-slag decontamination) was investigated to enable reuse and recycling of metal waste with very low surface dose rates at Fukushima Daiichi NPS. Assuming electric furnace melting, target elements were classified into 16 groups based on removal mechanisms identified by thermodynamic equilibrium and on chemical similarities in the periodic table, and transfer ratio ranges were assigned. The mechanisms were determined as transfer to the gas phase or absorption into slag based on saturation vapor pressure and Gibbs free energy change of oxide formation. Transfer ratio ranges were derived from slag/metal partition ratios or upper residual limits based on gas-liquid equilibrium. Using these ranges and separately evaluated waste inventories, an example of selecting important nuclides for clearance verification is presented.