DAMAGING EFFECTS 
OF RADIATION... 
On Chemical Materials 
By J. C. BRESEE, J. R. FLANARY, J. H. GOODE, C. D. WATSON, and J. S. WATSON 
Chemical Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 
IMPORTANT IN THE REPROCESSING of 
reactor fuels is the effect of radiation 
damage on process reagents and organic 
materials of construction, especially for 
short-cooled fuels where the fission- 
product radiation is very intense. The 
magnitude of the chemical and physical 
changes produced by radiation is suffi- 
cient to affect the usefulness, and even 
the feasibility, of some materials used 
in the recovery of uranium, thorium, 
and other materials from irradiated re- 
actor fuels. This article presents the 
details of how gamma radiation dam- 
ages organic protective coatings and 
gaskets. 
To simulate fission-product radia- 
tion, a cobalt-60 gamma source was used 
for these tests. Average gamma energy 
is 1.2 Mev. The source provided an 
intensity of 1.2-3.6 X 10‘r per minute 
in air; the maximum of total radiation 
accumulated by the test specimens was 
about 109 r. 
The specimens. Radiation stability 
of many industrial materials has been 
tested on a laboratory scale to aid in 
selecting materials for the construction 
and operation of radiochemical process- 
ing plants. The materials were ac- 
quired by: (a) accepting samples from 
vendors who solicited ORNL, and (b) 
nonexhaustive queries to vendors whose 
products appeared to be of interest. 
Materials that apparently exhibit 
poor radiation stability in these tests 
need not be considered inferior prod- 
ucts; slight variations in composition 
(such as the nature or content of plasti- 
cizers, binders, fillers, pigments, etc.) 
in many cases may affect radiation- 
stability properties quite drastically. 
Often a poorly rated product easily 
could be made to test higher by a shght 
change in raw materials or processing 
procedure. 
The tests are empirical and have been 
developed only for immediate compari- 
son purposes. Standard methods have 
not been established for radiation sta- 
bility, chemical resistance or decon- 
tamination tests, and because of the 
variety and number of samples a few 
Chemical Tests on Protective Coatings 
Quantitative measurements were made to determine how radiation affects the 
chemical resistance and chemical decontaminability of protective coatings. 
Resistance. Standard chemical-resistance tests were run on irradiated and 
unirradiated specimens. Cold-rolled steel immersion rods (3 in. dia, 6-in. long) 
with one rounded end were coated with the paint to be tested and were irradiated 
to various levels of accumulated radiation. Specimens that did not “‘fail’”’ (from 
visual observations) were immersed in several chemical reagents after an accumu- 
lated dose of about 109 r in air. The reagents were 3 molar nitric, sulfuric and 
hydrochloric acids, 3 molar sodium hydroxide, and an organic solvent (methyl 
isobutyl ketone or “‘hexone’’). The tests were continued until failure, or for a 
total of 9 days, and the results with irradiated specimens were compared with 
those for unirradiated specimens. 
A second phase of the chemical resistance studies occurred in the process of 
preparing specimens for decontamination tests. Protective coatings were applied 
to aluminum, steel, and concrete panels and were irradiated to various levels of 
accumulated radiation. The test panels then were contaminated with 0.1 ml 
fission products in 6 M HNO;. Many specimens that satisfactorily resisted 3 
molar HNO; during immersion tests were attacked by the contaminating acid, so 
several decontamination studies were rerun with 3 molar contaminating acid. 
Decontaminability. The chemical decontamination procedure consisted of 
scrubbing specimens that withstood the contaminating acid with water, 3 M HNO3, 
and in most cases concentrated citric acid. After each wash thé surface of the 
specimens were monitored and a decontamination factor (DF) was calculated. 
The process of contamination and decontamination was repeated three times or 
until the coating failed. 
The tests were performed in series, and essentially only those coatings that 
“‘nassed”’ the previous tests were subjected to later ones. Thus, only a few of the 
total number of coatings studied were carried through the decontamination tests. 
In many cases, mounted coatings were igradiated on two or three different 
types of surfaces—aluminum, steel, and concrete. The series of tests was neces- 
sary since the stability of an irradiated coating was strongly influenced by the 
surface to which it was applied. Similar tests were performed for each type of 
coated panel. 
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