Development of Concentration and Calcination Technology For High Level Liquid Waste

Conference · Sat Jul 01 04:00:00 EDT 2006

OSTI ID:21208698

Pande, D P ^[1]

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1. Back End Technology Development Division, Nuclear Recycle Group, BARC, Trombay- Mumbai (India)

The concentrated medium and high-level liquid radio chemicals effluents contain nitric acid, water along with the dissolved chemicals including the nitrates of the radio nuclides. High level liquid waste contain mainly nitrates of cesium, strontium, cerium, zirconium, chromium, barium, calcium, cobalt, copper, pickle, iron etc. and other fission products. This concentrated solution requires further evaporation, dehydration, drying and decomposition in temperature range of 150 to 700 deg. C. The addition of the calcined solids in vitrification pot, instead of liquid feed, helps to avoid low temperature zone because the vaporization of the liquid and decomposition of nitrates do not take place inside the melter. In our work Differential and thermo gravimetric studies has been carried out in the various stages of thermal treatment including drying, dehydration and conversion to oxide forms. Experimental studies were done to characterize the chemicals present in high-level radioactive waste. A Rotary Ball Kiln Calciner was used for development of the process because this is amenable for continuous operation and moderately good heat transfer can be achieved inside the kiln. This also has minimum secondary waste and off gases generation. The Rotary Ball Kiln Calciner Demonstration facility system was designed and installed for the demonstration of calcination process. The Rotary Ball Kiln Calciner is a slowly rotating slightly inclined horizontal tube that is externally heated by means of electric resistance heating. The liquid feed is sprayed onto the moving bed of metal balls in a slowly rotating calciner by a peristaltic type-metering pump. The vaporization of the liquid occurs in the pre-calcination zone due to counter current flow of hot gases. The dehydration and denitration of the solids occurs in the calcination zone, which is externally heated by electrical furnace. The calcined powder is cooled in the post calcination portion. It has been demonstrated that the Rotary Ball Kiln Calciner can be used for calcination of high level radioactive waste. The calcined product is consistent and uniform. The operation has been further optimized by on line data acquisition system. The results of laboratory studies and experimental results and design and operation of a demonstration plant are described in this paper. (authors)

• Research Organization: WM Symposia, Inc., PO Box 13023, Tucson, AZ, 85732-3023 (United States)
• OSTI ID: 21208698
• Report Number(s): INIS-US--09-WM-06231
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BARIUM NITRATES
CALCINATION
CALCIUM NITRATES
CERIUM NITRATES
CESIUM NITRATES
CHEMICAL EFFLUENTS
CHROMIUM NITRATES
COBALT NITRATES
COPPER NITRATES
FISSION PRODUCTS
HIGH-LEVEL RADIOACTIVE WASTES
LIQUID WASTES
STRONTIUM NITRATES
TEMPERATURE RANGE 0400-1000 K
ZIRCONIUM NITRATES