The effects of container materials and buffer additives on decreasing the iodide concentration in a disposal vault for spent nuclear fuel

To retard the migration of iodine released from a spent fuel after the break of a container, the reducing effects on the concentration of the iodide by container corrosion products and some buffer additives were examined in a solution with bentonite. Iron and copper, and their corrosion products scarcely reduced the iodide concentration. And kaolinite, chalcopyrite, pyrite, copper ore and galena, known as having a sorption property for iodine, did not noticeably sorb the iodide. However, palm active carbon, silver metal and Ag₂O lowered the iodide concentration. Especially, Ag₂O put into a disposal container would effectively hinder the migration of iodine to the outside of a disposal vault without a great loss if the pore size of the compacted buffer layer is maintained below 1 μ m.

Keywords:

• Iodine
• Migration
• Sorption
• Additive
• Silver oxide
• Bentonite

Notes

^a SGW: Synthetic groundwater.

^b RGW: Real groundwater. The experiment with RGW was performed in a nitrogen-filled glove box.

^c DW: Demineralized water.

^a DW: Demineralized water.