| 摘要 |
PURPOSE:To decompose safely sodium nitrate to gaseous NOx and sodium borate without accompanying the volatilization of radioactive substance by adding boric acid to sodium nitrate contg. the radioactive substance and heating the mixture to melt. CONSTITUTION:In a process for recovering the remaining nuclear fuel substance or the like from the fuel after the usage, sodium nitrate contg. radioactive substance is obtained as a by-product. Boric acid (or boron oxide) are added to sodium nitrate and the mixture is decomposed to sodium borate and NOx at comparatively low temperature by heating and melting the mixture (it is preferable to use a microwave heating furnace). Also, in this method, it is possible to obtain a stable borosilicate glass instead of producing sodium nitrate by adding glass forming material such as silicates in addition to boric acid and heating the mixture to melt.
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