REMOVAL OF BOND SODIUM FROM AN IRRADIATED FULL-LENGTH EXPERIMENTAL BREEDER REACTOR – II BLANKET ELEMENT VIA MELT-DRAIN-EVAPORATE PROCESS

摘要

An experimental study was performed on anirradiated full-length blanket element from ExperimentalBreeder Reactor-Ⅱ (EBR-Ⅱ) to remove its bond sodiumusing a melt-drain-evaporate (MEDE) process. Theremoval of bond sodium from an EBR-Ⅱ blanket elementeliminates its reactive characteristic and, thereby,facilitates additional options in the disposition of thisblanket material. Previous investigations identified theeffective removal of bond sodium from irradiated EBR-IIblanket elements that were chopped into 1.8-cm lengthsprior to subjecting them to a MEDE process. Anobjective of this study was to assess the effectiveness ofremoving bond sodium from an irradiated full-lengthEBR-II blanket element. Additionally, the ability toseparate the blanket slugs from the full-length claddingwas evaluated. The approach for this study involvedbreaching a relatively high burn-up blanket elementabove and below the column of blanket slugs (140-cmtotal height) and subjecting the breached element toelevated temperature and reduced pressure in a sealedsystem to melt, drain, and evaporate the bond sodiumaway from the blanket material. The treated element wasremoved from the MEDE apparatus and all five blanketslugs (each 1.10-cm diameter by 28-cm long) wereseparated from the cladding. Dimensional analysis of theseparate blanket slugs identified appreciable swelling intwo of the slugs, which were positioned near the midheightof the blanket column. Samples of each blanketslug and its adjacent cladding were prepared forelemental and isotopic analyses to characterize theblanket and cladding materials and verify the absence ofbond sodium. The separated bond sodium was collectedand stored for future deactivation and disposition studies.