Predictions of PuO sub 2 and tracer compound release from ISV melts
- Engineering Science and Analysis, Albuquerque, NM (United States)
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
Two field tests were conducted at the Idaho National Engineering Laboratory (INEL) to assess in situ vitrification (ISV) suitability for long-term stabilization of buried radioactive waste. Both tests contained rare-earth oxide tracers (DY{sub 2}O{sub 3}, Yb{sub 2}O{sub 3}, and Tb{sub 4}O{sub 7}) to simulate the presence of plutonium in the form of PuO{sub 2}. In the first test, Intermediate Field Test (IFT)-l, approximately 4-% release of tracer material occurred during soil melting and associated off-gassing, while essentially nil release was observed for the second experiment (IFT-2) for which off-gassing was much reduced. This report presents an evaluation of the IFT test data in terms of governing release processes. Prediction of tracer release during ISV melting centered on an assessment of three potential transport mechanisms, (a) tracer diffusion through stagnant pool, (b) tracer transport by convective currents, and (c) tracer carry-off by escaping gas bubbles. Analysis indicates that tracer release by escaping gas is the dominant release mechanism, which is consistent with video records of gas bubble escape from the ISV melt surface. Quantitative mass transport predictions were also made for the IFT-I test conditions, indicating similarity between the 4-% release data and calculational results at viscosities of {approx} poise and tracer diffusivities of {approx}10{sub {minus}6} CM{sup 2}/s. Since PuO{sub 2} has similar chemical and transport (diffusivity) properties as the rare-earth tracers used in the rare earth tracers used in the IFT experiments, release of PuO{sub 2} is predicted for similar off-gassing conditions. Reduced off-gassing during ISV would thus be expected to improve the overall retention of heavy-oxides within vitrified soil.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 7066843
- Report Number(s):
- EGG-WTD-10172; ON: DE92018050
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GASEOUS WASTES
MONITORING
RADIOACTIVE WASTES
IN-SITU PROCESSING
VITRIFICATION
TRACER TECHNIQUES
EVALUATION
BUBBLES
DYSPROSIUM OXIDES
MASS TRANSFER
MELTING
PLUTONIUM DIOXIDE
REMEDIAL ACTION
SOILS
TERBIUM OXIDES
YTTERBIUM OXIDES
ACTINIDE COMPOUNDS
CHALCOGENIDES
DYSPROSIUM COMPOUNDS
ISOTOPE APPLICATIONS
MATERIALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PLUTONIUM COMPOUNDS
PLUTONIUM OXIDES
PROCESSING
RADIOACTIVE MATERIALS
RARE EARTH COMPOUNDS
TERBIUM COMPOUNDS
TRANSURANIUM COMPOUNDS
WASTES
YTTERBIUM COMPOUNDS
052002* - Nuclear Fuels- Waste Disposal & Storage