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Title: Optimization of the factors that accelerate leaching

The prediction of long-term leachability of low-level radioactive waste forms is an essential element of disposal-site performance assessment. This report describes experiments and modeling techniques used to develop an accelerated leach test that meets this need. The acceleration in leaching rates caused by the combinations of two or more factors were experimentally determined. These factors were identified earlier as being able to individually accelerate leaching. They are: elevated temperature, the size of the waste form, the ratio of the volume of leachant to the surface area of the waste form, and the frequency of replacement of the leachant. The solidification agents employed were ones that are currently used to treat low-level radioactive wastes, namely portland type I cement, bitumen, and vinyl ester-styrene. The simulated wastes, sodium sulfate, sodium tetraborate, and incinerator ash, are simplified representatives of typical low-level waste streams. Experiments determined the leaching behavior of the radionuclides of cesium (Cs-137), strontium (Sr-85), and cobalt (Co-60 or Co-57) from several different formulations of solidification agents and waste types. Leaching results were based upon radiochemical and elemental analyses of aliquots of the leachate, and on its total alkalinity and pH at various times during the experiment (up to 120 days). Solidmore » phase analyses were carried out by Scanning/Electron Microscopy and Energy Dispersive Spectroscopy on the waste forms before and after some leaching experiments. 43 refs., 96 figs., 16 tabs.« less
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
5624066
Report Number(s):
BNL-52204
ON: DE90000886; TRN: 89-027900
DOE Contract Number:
AC02-76CH00016
Resource Type:
Technical Report
Research Org:
Brookhaven National Lab., Upton, NY (USA)
Sponsoring Org:
DOE/NE
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; LEACHING; MATHEMATICAL MODELS; LOW-LEVEL RADIOACTIVE WASTES; GROUND DISPOSAL; CEMENTS; CESIUM 137; COBALT 57; COBALT 60; ENVIRONMENTAL IMPACTS; LIQUID WASTES; SOLIDIFICATION; STRONTIUM 85; WASTE FORMS; ALKALI METAL ISOTOPES; ALKALINE EARTH ISOTOPES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BUILDING MATERIALS; CESIUM ISOTOPES; COBALT ISOTOPES; DAYS LIVING RADIOISOTOPES; DISSOLUTION; ELECTRON CAPTURE RADIOISOTOPES; EVEN-ODD NUCLEI; HOURS LIVING RADIOISOTOPES; INTERMEDIATE MASS NUCLEI; INTERNAL CONVERSION RADIOISOTOPES; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; MANAGEMENT; MATERIALS; MINUTES LIVING RADIOISOTOPES; NUCLEI; ODD-EVEN NUCLEI; ODD-ODD NUCLEI; PHASE TRANSFORMATIONS; RADIOACTIVE MATERIALS; RADIOACTIVE WASTES; RADIOISOTOPES; SEPARATION PROCESSES; STRONTIUM ISOTOPES; WASTE DISPOSAL; WASTE MANAGEMENT; WASTES; YEARS LIVING RADIOISOT; YEARS LIVING RADIOISOTOPES 052002* -- Nuclear Fuels-- Waste Disposal & Storage; 053000 -- Nuclear Fuels-- Environmental Aspects