KINETICS OF THE DECOMPOSITION OF ORGANIC REACTOR COOLANTS (thesis)

Technical Report · Tue Jul 01 04:00:00 EDT 1958

OSTI ID:4291538

de Halas, D R

The kinetics of the decomposition of several polyphenyl compounds were investigated under the influence of pyrolysis and radiolysis. It was found that all of the polyphenyl compounds investignted polymerized according to a first order rate law under the single influence of reactor radiation or gamma rays or pyrolysis. That is, the rate of polymerization was directhy propontional to the amount of remaining unpolymerized material. When the polyphenyl material was simultaneously undergoing radiolysis and pyrolysis, the situation was found to be more complex. At moderate temperatures, 200 to 400 deg C, the pyrolysis of the polyphenyl was negligible compared to the radiolysis. However, in this temperature range the polymers formed by radiolysis were partially degraded by thermal action. The resulting rate law fhr polymerization includes a term for this back reaction. At higher temperatures, above about 400 deg C, the pyrolysis became the dominating reaction, and the effects of radiation could be neglected. It was found that all of the compounds investigated polymerized at almost identical rates under irradiation. However, there were notable differenccs in pyrolytic polymerization rates between the various polyphenyl compounds. Because pyrolysis is much more important than radiolysis at high temperature, the thermal stability of the coolants is the factor which determines the maximum temperature at which the coolant can be utilized. The compounds in order of decreasing thermal stability are: biphenyl, all three terphenyl isomers, monomethylbiphenyl, and monoisopropylhiphenyl. These studies also brought out differences in the decoinposition products formed by radiolysis and pyrolysis. In general, the products formed during the former process were polymerized to a greater degree than those formed by pyrolysis. The products formed by gamma ray and neutron radiolysis were quite similar but showed minor differences in composition. The relative damaging power of neutrons and gamma rays was compared on the basis of the mount of polymerization caused by the absorption of a ven amount of energy in the hydrocarbon. Fast neutrons were found to cause about 50 to 200 per cent more damage than that caused hy the absorption of an equal amount of gamma ray energy. (auth)

• Research Organization: General Electric Co. Hanford Atomic Products Operation, Richland, Wash.
• DOE Contract Number: W-31-109-ENG-52
• NSA Number: NSA-13-000106
• OSTI ID: 4291538
• Report Number(s): HW-56769
• Country of Publication: United States
• Language: English

Related Subjects

CHEMISTRY
COMPOUNDS
DECOMPOSITION
ETHYL RADICALS
FAST NEUTRONS
GAMMA RADIATION
HIGH TEMPERATURE
ISOMERS
MEASURED VALUES
NEUTRON BEAMS
ORGANIC COOLANT
POLYMERIZATION
POLYPHENYLS
PYROLYSIS
RADIATION CHEMISTRY
RADIATION EFFECTS
REACTION KINETICS
STABILITY
TEMPERATURE
TERPHENYLS
USES