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Title: Thermal Stabilization of Polycubes by Air Oxidation Results of Testing Unirradiated Polystyrene

Abstract

Polystyrene samples were tested to determine if the polycubes stored at the Plutonium Finishing Plant could be stabilized safely by a thermal air oxidation process using existing production furnaces. Polycubes are compression-molded mixtures of plutonium oxide and/or uranium oxide in a polystyrene matrix. The irradiated polystyrene that forms the matrix of the polycubes will be high and crosslinked because of radiolysis. The behavior of the crosslinked polystyrene used in most of the tests reported here (polystyrene--8% divinyl benzene) appears to imitate polystyrene crosslinked by radiation. This material is more stable toward pyrolysis, is more reactive with oxygen, and produces more carbonaceous char and less flammable gas during oxidation than non-crosslinked polystyrene. The testing showed that air oxidation of polystyrene begins when it is heated to about 200 C in air. The more highly crosslinked polystyrene is oxidized more complete, and at lower temperatures. Pyrolysis is first observed at about 350 C in air and both oxidation and pyrolysis reactions occur simultaneously until about 420 C is reached, where the remaining carbonaceous chnr begins to oxidize. Oxidation is essentially complete in air at about 550 C. The gases evolved in the early stages of heating are mainly oxidation products (water, carbonmore » dioxide, and benzaldehyde). When pyrolysis begins, a mixture of these oxidation products and hydrocarbon pyrolysis products (styrene, benzene, toluene, and indane) are evolved. The char oxidation step yields only carbon dioxide and water. The overall yields of gas were about 87% by weight oxidation products and 13% pyrolysis products. Concentrations of flammable hydrocarbon pyrolysis gases under normal operating conditions are estimated to be less than 5% of the lower Flammability limit. Benzaldehyde concentrations could be as high as 46% of the lower flammability limit, depending on the heating rate and the number of polycubes being processed. These results indicate that air oxidation of the polycubes can be controlled safety by controlling the furnace temperature and airflow rate through the furnace. The oxidation reaction appears to be rapid enough to allow reasonable throughput of the polycubes in the production furnaces.« less

Authors:
Publication Date:
Research Org.:
FH (US)
Sponsoring Org.:
USDOE Office of Environmental Management (EM) (US)
OSTI Identifier:
808247
Report Number(s):
HNF-6144, Rev.0
TRN: US0302310
DOE Contract Number:  
AC06-96RL13200
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 May 2000
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; BENZALDEHYDE; BENZENE; CARBON DIOXIDE; HEATING RATE; OXIDATION; PLUTONIUM OXIDES; POLYSTYRENE; PYROLYSIS PRODUCTS; STABILIZATION; MATERIALS TESTING; URANIUM OXIDES

Citation Formats

BARNEY, G S. Thermal Stabilization of Polycubes by Air Oxidation Results of Testing Unirradiated Polystyrene. United States: N. p., 2000. Web. doi:10.2172/808247.
BARNEY, G S. Thermal Stabilization of Polycubes by Air Oxidation Results of Testing Unirradiated Polystyrene. United States. doi:10.2172/808247.
BARNEY, G S. Mon . "Thermal Stabilization of Polycubes by Air Oxidation Results of Testing Unirradiated Polystyrene". United States. doi:10.2172/808247. https://www.osti.gov/servlets/purl/808247.
@article{osti_808247,
title = {Thermal Stabilization of Polycubes by Air Oxidation Results of Testing Unirradiated Polystyrene},
author = {BARNEY, G S},
abstractNote = {Polystyrene samples were tested to determine if the polycubes stored at the Plutonium Finishing Plant could be stabilized safely by a thermal air oxidation process using existing production furnaces. Polycubes are compression-molded mixtures of plutonium oxide and/or uranium oxide in a polystyrene matrix. The irradiated polystyrene that forms the matrix of the polycubes will be high and crosslinked because of radiolysis. The behavior of the crosslinked polystyrene used in most of the tests reported here (polystyrene--8% divinyl benzene) appears to imitate polystyrene crosslinked by radiation. This material is more stable toward pyrolysis, is more reactive with oxygen, and produces more carbonaceous char and less flammable gas during oxidation than non-crosslinked polystyrene. The testing showed that air oxidation of polystyrene begins when it is heated to about 200 C in air. The more highly crosslinked polystyrene is oxidized more complete, and at lower temperatures. Pyrolysis is first observed at about 350 C in air and both oxidation and pyrolysis reactions occur simultaneously until about 420 C is reached, where the remaining carbonaceous chnr begins to oxidize. Oxidation is essentially complete in air at about 550 C. The gases evolved in the early stages of heating are mainly oxidation products (water, carbon dioxide, and benzaldehyde). When pyrolysis begins, a mixture of these oxidation products and hydrocarbon pyrolysis products (styrene, benzene, toluene, and indane) are evolved. The char oxidation step yields only carbon dioxide and water. The overall yields of gas were about 87% by weight oxidation products and 13% pyrolysis products. Concentrations of flammable hydrocarbon pyrolysis gases under normal operating conditions are estimated to be less than 5% of the lower Flammability limit. Benzaldehyde concentrations could be as high as 46% of the lower flammability limit, depending on the heating rate and the number of polycubes being processed. These results indicate that air oxidation of the polycubes can be controlled safety by controlling the furnace temperature and airflow rate through the furnace. The oxidation reaction appears to be rapid enough to allow reasonable throughput of the polycubes in the production furnaces.},
doi = {10.2172/808247},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {5}
}

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