GLYCOLIC ACID PHYSICAL PROPERTIES, IMPURITIES, AND RADIATION EFFECTS ASSESSMENT

Pickenheim, B. ; Bibler, N.

Savannah River Site (S.C.)

关键词: Flowsheets;    Radiolysis;    Radioactive Waste Facilities;    Waste Forms;    Glass;   

DOI  :  10.2172/982752
RP-ID  :  SRNL-STI-2010-00314
RP-ID  :  DE-AC09-08SR22470
RP-ID  :  982752

美国|英语

来源: UNT Digital Library

【 摘 要 】

The DWPF is pursuing alternative reductants/flowsheets to increase attainment to meet closure commitment dates. In fiscal year 2009, SRNL evaluated several options and recommended the further assessment of the nitric/formic/glycolic acid flowsheet. SRNL is currently performing testing with this flowsheet to support the DWPF down-select of alternate reductants. As part of the evaluation, SRNL was requested to determine the physical properties of formic and glycolic acid blends. Blends of formic acid in glycolic acid were prepared and their physical properties tested. Increasing amounts of glycolic acid led to increases in blend density, viscosity and surface tension as compared to the 90 wt% formic acid that is currently used at DWPF. These increases are small, however, and are not expected to present any difficulties in terms of processing. The effect of sulfur impurities in technical grade glycolic acid was studied for its impact on DWPF glass quality. While the glycolic acid specification allows for more sulfate than the current formic acid specification, the ultimate impact is expected to be on the order of 0.03 wt% sulfur in glass. Note that lower sulfur content glycolic acid could likely be procured at some increased cost if deemed necessary. A paper study on the effects of radiation on glycolic acid was performed. The analysis indicates that substitution of glycolic acid for formic acid would not increase the radiolytic production rate of H{sub 2} and cause an adverse effect in the SRAT or SME process. It has been cited that glycolic acid solutions that are depleted of O{sub 2} when subjected to large radiation doses produced considerable quantities of a non-diffusive polymeric material. Considering a constant air purge is maintained in the SRAT and the solution is continuously mixed, oxygen depletion seems unlikely, however, if this polymer is formed in the SRAT solution, the rheology of the solution may be affected and pumping of the solution may be hindered. A series of tests to determine whether the polymer will be formed is currently being outlined. The first phase will be a simple experiment where a simulated SRAT supernatant containing the 80:20 blend of glycolic - formic acid could be irradiated in the Co-60 gamma source at SRNL to a very large dose resembling the dose received by the radioactive SRAT solution after several weeks. The resulting solution could then be heated to simulate refluxing in the SRAT process. Finally a radioactive demonstration of the SRAT process should be performed in the SRNL Shielded Cells to confirm successful execution of the glycolic - formic acid flowsheet.