Vitrification of radioactive high-level waste by spray calcination and in-can melting

Hanson, Mark D.; Bjorklund, W.J.

doi:10.2172/5168786

Cited by 3 publications

(3 citation statements)

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“…The feasibility of producing glass from simulated nuclear wastes and glass formers was demonstrated more than 20 years ago (White and LaHaie 1955;Watson et ale 1958;Goldman et ale 1958). Engineering-scale demonstrations using actual HLW have been conducted in the United States (McElroy et ale 1972;Hanson and Bjorklund 1980). High-level waste has been converted to glass in a production process in France (Sombret 1978).…”

Section: Glass Meltersmentioning

confidence: 99%

Consolidated waste forms: glass marbles and ceramic pellets

Treat¹,

Rusín²

1982

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Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured from a melter in a continuous stream into a marble-making device. Marbles were produced at PNL on a vibratory marble machine at rates as high as 60 kg/h. Other marble-making concepts were also investigated. The marble process, including a lead-encapsulation step, was judged as one of the more feasible processes for immobilizing high-level wastes. To produce ceramic pellets, a series of processing steps are required, which include: • spray calcining-to dry liquid wastes to a powder; • disc pelletizing-to convert waste powders to spherical pellets; • sintering-to densify pellets and cause desired crystal formation. These processing steps are quite complex, and thereby render the ceramic pellet process as one of the least feasible processes for immobilizing highlevel wastes.

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Section: Glass Meltersmentioning

confidence: 99%

Consolidated waste forms: glass marbles and ceramic pellets

Treat¹,

Rusín²

1982

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“…This full-scale unit has solidified ~390,000 L of simulated wastes during 1830 h of processing time • To complete spray calciner/melter process development for plant application, a process verification program (Nuclear Waste Vitrification Program) was implemented. The program included the processing of actual high-level waste from spent nuclear power-reactor fuels into borosilicate glass and filling two canisters with this glass in 1979 (Wheelwright et al 1979;Bonner et al 1980;Hanson and Bjorklund 1980). The pilot-scale unit (about a 15-L/h feed capacity) produced two canisters [20 em (8 in.…”

Section: Introductionmentioning

confidence: 99%

Design and performance of a full-scale spray calciner for nonradioactive high-level-waste-vitrification studies

Miller¹

1981

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Since 1977, the Pacific Northwest Laboratory has tested a large-scale spray calciner for the solidification of simulated high-level neutralized and acid radioactive wastes. This is a report of valuable operating experience gained during 1830 h of processing time in which ~390,000 L of simulated wastes were solidified.Experience from spray calciner operations has demonstrated that atomizing-nozzle flow conditions that produce 100-~ median-volume-diameter or smaller droplets are required for large-scale spray calciners. Both internal-and external-mix nozzles have been tested. Due to its lower airflow requirements and the fewer large droplets produced, the internal-mix nozzle has been chosen for primary development in the spray calciner program at PNL. Atomizing nozzle air caps made of reaction-bonded or hot-pressed silicon nitride should provide satisfactory wear resistance and thermal shock resistance for long-term spray calciner operation.While several alternative feed system components exist, spray calciner feed system experience at PNL has been primarily with a centrifugal pump, control valve, and magnetic flowmeter. This system has performed satisfactorily, and problems have been limited to the following:• occasional plugging in the magnetic flowmeter by large foreign particles. (This problem was solved by reducing the size of the strainer-screen mesh to remove particles larger than the flowmeter orifice and by installing a larger flowmeter that had a 0.64-cm orifice instead of a 0.40-cm opening.)• erosion of the pump impeller housing, pipe elbows and ball valve in the feed tank's 304L stainless steel recirculation line resulting from feeds containing a high percentage of solids. (Solutions to this problem include use of a more erosion-resistant piping material, long-radius elbows or piping bends, ball valves with port diameters at least as large as the pipe's inside diameter, and lower fluid velocities.)• minor settling of solids around the outside edges on the bottom of the flat-bottomed tank. (Use of tank with a conical or dished bottom would be a solution to this problem.)The spray calciner has been operated at chamber wall temperatures from 400° to 900°C, depending on the type of waste feed and the feedrate. Calcine sintering, corrosion, and thermal stresses limit the maximum temperature. Rates up to 400 L/h have been demonstrated.Total furnace power requirements (not including heat losses) can be predicted by assuming that the waste feed is water and calculating the sensible and latent heat required to raise the inlet feed and atomizing air to the desired offgas outlet temperature. Furnace power consumption is not axially uniform. Data from actual calciner operation indicate that 60% of the power input is supplied by the lower half of the furnace. This is likely due to convective flow patterns inside the spray chamber.

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“…Recycle liquid can be fed to the upper and lower weir. Condensate from the steam jet and E-119 condenser is routed to the collection vessel at the bottom of the scrubber to replace solution that has drained from the scrubber.During operation in the Nuclear Waste Vitrification Program (NWVP)(Hanson and Bjorklund 1980), the quench scrubber had a maximum pressure drop of 10 em of water. The flooding point for the packing at gas flow of 55 kg/h to 60'C was 2.2 L/sec.…”

mentioning

confidence: 99%

Design features of the radioactive Liquid-Fed Ceramic Melter system

Holton

1985

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Vitrification of radioactive high-level waste by spray calcination and in-can melting

Cited by 3 publications

References 0 publications

Consolidated waste forms: glass marbles and ceramic pellets

Consolidated waste forms: glass marbles and ceramic pellets

Design and performance of a full-scale spray calciner for nonradioactive high-level-waste-vitrification studies

Design features of the radioactive Liquid-Fed Ceramic Melter system

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