Foreword

Choppin, Gregory R.; Liljenzin, Jan‐Olov; Rydberg, Jan

doi:10.1016/b978-075067463-8/50000-5

Cited by 53 publications

(79 citation statements)

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“…It is possible that the lower pH was caused by radiolysis of atmospheric nitrogen during sludge storage. Radiolysis of humid air produces nitric acid (HNO 3 ; Choppin et al 2002) and radiolytic nitrate was observed in long-term testing of UO 2 corrosion (Wronkiewicz et al 1996). The observed pH increased slightly (~0.2 pH units) after hydrothermal reactions for Test 1 and decreased about 0.6 pH units for Test 2.…”

Section: Tests 1 Andmentioning

confidence: 94%

Hydrothermal Testing of K Basin Sludge and N Reactor Fuel at Sludge Treatment Project Operating Conditions

Delegard¹,

Schmidt²,

Thornton³

2007

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Executive SummaryFive bench-scale tests (~50 ml each) were conducted in sealed, un-agitated reaction vessels using sludge samples collected from the K East Basin and particles/coupons of irradiated N Reactor fuel (also from the K Basins). These tests were designed to evaluate and understand the chemical changes that may be occurring under the hydrothermal conditions (e.g., 7 to 72 h at 185°C) of the Sludge Treatment Project (STP) corrosion process and the effects that any changes would have on sludge rheological properties. The two sludge formulations used in these tests were selected to represent nominal (vs. bounding) compositions of the two major sludge feed streams to the STP process. The scoping tests were not designed to evaluate engineering aspects of the process.The hydrothermal treatment affected the chemical and physical properties of the sludge. In each test, significant uranium compound phase changes were identified, resulting from dehydration and chemical oxidation and reduction reactions. Physical properties of the sludge were significantly altered from their initial, as-settled, sludge values including, shear strength, settled density, weight percent water, and gas retention.The high uranium content sludge (~70 wt% uranium) set up to form a very stiff solid that exhibited very high shear strength (120,000 to 170,000 Pa) after hydrothermal treatment at 185°C for 7 to 10 hours under static (unstirred) conditions. Shear strengths of untreated sludge range from about 270 to 8100 Pa. Also, the hydrothermal treatment reduced the water content in the settled sludge by about 20 wt%. The treated sludge was difficult to remove from the Teflon test vessels, with sludge firmly adhering to the Teflon vessel surfaces. The strength of the treated sludge was further evaluated by agitation in water. In a 600-ml beaker, with 400 ml water at ~30°C, the diameters of agglomerates were reduced by about 40 to 50% after 1 hour of agitation with a 5.08-cm (2-in.) diameter impeller rotated at a tip speed of 80 cm/s.Further static tests with lower uranium-content sludges (~16 wt% uranium) run 72 h at 185°C produced softer solids with 9,000 to 16,000 Pa shear strengths. While some sludge adhered to the Teflon liner, it was not tenaciously bound. The agglomerates from these tests were relatively weak and, in some cases, were disintegrated with a gentle stream of water. The water content in the settled sludge was not significantly affected by the hydrothermal treatment.Chemical phase alteration, observed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry, gave evidence that solids dissolution followed by precipitation was responsible for the increased strengths of the sludge products. The presence of organic ion exchange resin (OIER) and polymer flocculent (constituents known to be in K Basin sludge) in the lower uranium-content sludge did not appear to have a significant impact on the physical behavior of the post-treated sludge.Four irradiated uranium metal fuel coupons were included in on...

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Section: Tests 1 Andmentioning

confidence: 94%

Hydrothermal Testing of K Basin Sludge and N Reactor Fuel at Sludge Treatment Project Operating Conditions

Delegard¹,

Schmidt²,

Thornton³

2007

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“…91 By comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in microwave assisted extraction and solvent extraction, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. 92 …”

Section: Food Decompositionmentioning

confidence: 99%

Chemical Kinetics and Reaction Mechanisms in Solvent Extraction: New Trends and Applications

El-Hefny¹

2017

JPS

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“…After spent nuclear fuel is processed to remove plutonium and uranium by PUREX extraction, 95% of the waste mass is nitric acid introduced by reprocessing [15]. With plasma reprocessing, no working fluid is introduced, and output streams are solids which are easier to store and vitrify than liquid wastes [14].…”

Section: Plasma Mass Separationmentioning

confidence: 99%

Plasma Mass Filters For Nuclear Waste Reprocessing

Fetterman

Fisch

2011

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Practical disposal of nuclear waste requires high-throughput separation techniques. The most dangerous part of nuclear waste is the fission product, which contains the most active and mobile radioisotopes and produces most of the heat. We suggest that the fission products could be separated as a group from nuclear waste using plasma mass filters. Plasmabased processes are well suited to separating nuclear waste, because mass rather than chemical properties are used for separation. A single plasma stage can replace several stages of chemical separation, producing separate streams of bulk elements, fission products, and actinoids. The plasma mass filters may have lower cost and produce less auxiliary waste than chemical processing plants. Three rotating plasma configurations are considered that act as mass filters: the plasma centrifuge, the Ohkawa filter, and the asymmetric centrifugal trap.

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Foreword

Cited by 53 publications

References 0 publications

Hydrothermal Testing of K Basin Sludge and N Reactor Fuel at Sludge Treatment Project Operating Conditions

Hydrothermal Testing of K Basin Sludge and N Reactor Fuel at Sludge Treatment Project Operating Conditions

Chemical Kinetics and Reaction Mechanisms in Solvent Extraction: New Trends and Applications

Plasma Mass Filters For Nuclear Waste Reprocessing

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