Thermal decomposition of ammonium perchlorate during gamma-ray irradiation Page: 2 of 4
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spectrometer and optical relay system. All sensitive equipment is outside of the
radiation field. Absorption, luminescence, gas evolution, and numerous other
measurements can be made, usually simultaneously, during irradiation.
Gas evolution studies have been made on single crystals and powders of
ainonium perchlorate, both at room temperature and at 2270C. Figure 1 shows a gas
pressure vs. time curve for commercial powder being exposed at approximately 100R/s.
This sample had not been irradiated previously. The curve increases in a smooth
monotonic fashion. In marked contrast, the single crystal curve, Fig. 2, shows
abrupt burst-like spikes superimposed on a continuous background. The spikes
appear to occur at random times. Most likely they are caused by the abrupt release
of gas, and the subsequent partial readsorption, accompanying micro fracture. The
appearance of these spikes at.these doses is not entirely unexpected. The previous
microscope studies indicated they should occur when the exposure reached 106 or
The gas pressure vs. time curve obtained by decomposing at 227C without radia-
tion, Fig. 3, closely resembles similar curves obtained in the past, and with other
apparatus. The other curves in Fig. 3, and the enlarged initial part, Fig. 4,
were obtained by "turning-on" the source 1, 10 and 20 minutes after the thermal de-
composition process had been started. In this case the exposure rate is 4.5 R/sec.
In other words, these curves were obtained by simultaneously irradiating and heat-
ing. First, there is a marked decrease in the induction period. The observed
periods are 23.5, 26.2, and 30.0 minutes for the 1, 10 and 20 minute delays between
heating and irradiation.
The importance of this induction period data is demonstrated by comparison
with data, summarized by Eq. 1, from samples exposed at room temperature prior
to heating. When the irradiation is started one minute after heating the sample
has accumulated approximately 6,000 R in the 23.5 minutes required to reach the
end of the induction period. To achieve the same reduction by first irradiating
and then heating the sample would have to accumulate an exposure of 2 x 105 R.
The corresponding exposures for the 10 and 20 delays are 1 x 105 and 5 x 104. Thus,
simultaneous heat and irradiation has produced a large synergistic effect.
Figures 3 and 4 indicate that irradiation has not effected the acceleratory
and decay periods. Also, the numerous spikes shown in Fig. 1 are not observed.
Lastly, preliminary measurements, in which the exposure rates are as low as
1R/s, show similar large effects.
These observations lead to a number of conclusions. To begin, since these
are, as far as we can determine, the first thermal decomposition measurements made
during irradiation, and since they show large effects, they should be confirmed
and expanded upon. In particular, they should be repeated using electron, x-ray,
fission and 14 MeV neutron irradiations, etc. They point to the possibility that
reactive systems, particularly propellants and pyrotechnic devices may be particu-
larly susceptible to radiation during use. Finally, to evaluate radiation hazards
in these systems it is essential to obtain improved understanding of the radiation
related mechanisms involved.
This report was prepared as an account of work
sponsored by the United States Government. Neither
the United States nor the United States Energy
Research and Development Administration, nor any of
bhir employees, nor any of their contractors,
subcontractors, or their employees, makes any
warranty, expre or implied, or assumes any legal -2-
liability or respontsa ility for the accuracy, completeness
or usefulness of any information, apparatus, product or
process disclosed, or represents that its use would not
infringe privately owned rights.
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Fuller, G.E. & Levy, P.W. Thermal decomposition of ammonium perchlorate during gamma-ray irradiation, article, January 1, 1975; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc1021441/m1/2/: accessed November 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.