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Aging Effects on Fire-Retardant Additives in Organic Materials for Nuclear Plant Applications
(NUREG/CR-2868)
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Publication Information
Printed August 1982
Aging Effects on Fire-Retardant Additives in Organic Materials for Nuclear Plant Applications
Roger L. Clough
Sandia National Laboratories
Albuquerque, New Mexico 87185
operated by Sandia National Laboratories
for the
U. S. Department of Energy
Prepared for Electrical Engineering Branch
Division of Engineering Technology
Office of Water Reactor Safety Research
U. S. Nuclear Regulatory Commission
Washington, DC 20555
Under Interagency Agreement DOE 40-550-75
NRC FIN No. A-1051
Availability
Notice
Abstract
Inhibiting fire is a major concern of nuclear safety. One
of the most widely used commercial fire-retardant additives
incorporated into cable insulation and other organic materials
to reduce their flammability has been the halocarbon (usually a
chlorinated hydrocarbon),typically in combination with antimony
oxide. Such materials may be installed for the design lifetime
of a nuclear plant; this report describes an investigation of
the long-term aging behavior of these fire-retardant additives
in polymeric materials.
Extensive aging experiments on fire-retarded formulations
of ethylene propylene r,'-er (EPR) and of chlorosulfonated polyethylene
(CSPE) have been carried out, with chemical analysis of
halogen and antimony content performed as a function of aging
time and conditions. Oxygen index flammability measurements were
also performed on selected samples. Significant fire-retardant
losses (both chlorine (Cl) and antimony (Sb)) were found to occur
in certain of the fire-retardant materials but not in others, de-pending
on the molecular structure of the particular halogen-containing
component. The Cl:Sb loss ratios indicate that a
chemical reaction takes place under the aging conditions to
form the volatile compound, antimony trichloride (SbC1 3 ). The
EPR formulations showed a modestly increased flammability with
fire-retardant loss on aging. CSPE materials exhibited a
significant decrease in flammability on aging despite the
loss of flame retardants. This appears to be correlated
with the loss of flammable, volatile components from the
formulation.
Using the activation energy of 34 kcal/mol derived from Arrhenius treatment of the antimony loss data for the EPR
formulation having the most rapid loss rate, it is predicted that fire-retardant loss should become appreciable for this
material only at substantially elevated temperatures or exceedingly
long times. The data indicate that the loss of
halogen- and antimony-based fire retardants appears to be insignificant under ambient conditions expected for nuclear plants.
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