FIG. 2. 
contact 
for five days at 20°C 
face bond normally is quite weak (for 
stripeoats, deliberately so), and radi- 
ation-caused changes in the bond are 
less important than changes in the 
physical properties of the coating. 
Gamma damage to unmounted coat- 
ings is shown in Table 1. 
The main requirements for a radi- 
ation-resistant stripcoat are that the 
coating surface retain its integrity and 
the film its flexibility so that decon- 
tamination can be carried out by re- 
moving the coating after irradiation. 
In four of the five stripcoat tests, the 
surface remained intact, but the film 
became brittle and broke during a 
bending test; these stripcoats could 
not,be removed readily after 10° r. 
The fifth strip coat, G. E. Cocoon, 
remained flexible but the surface be- 
came very tacky. There is a possi- 
bility that the film porosity increased 
with irradiation, but no quantitative 
Disassembled 347 stainless steel test flanges show corrosion resulting from 
with Teflon disk (center) during 10° r irradiation immersed in 50% HNO; 
tests were carried out to establish this 
point. 
The proposed use of both T-locked 
coatings and flame-sprayed polyethyl- 
ene called for flexibility of the coatings. 
The unmounted tests indicated that ~ 
both types were seriously embrittled by 
exposure to 10° r._ However, applica- 
tions without the need for flexibility 
(e.g., a T-locked surface for a concrete 
cell wall) would be possible provided 
that the sheet porosity had not in- 
creased. Again, porosity tests were 
not carried out. 
Mounted coatings. Table 2 pre- 
sents the results of screening studies of 
mounted protective coatings. It shows 
the gamma dose at which the coating 
failed or the maximum dose applied to 
the coating without failure. 
The influence of the surface to which 
the coating is applied on the stability 
of the coating is seen by comparing the 
70 ° 
Ip 
1s 
65 13 
S Asphalt + ols = 
S [25% barite | 
— H ° 
—g60 \ ze 
= \ 42; 
— | 5.29 
55 
4 
°o 
Penetration in 5 sec ot 77°F with 100 
2075 
200 225 
Softening Point, RGB (*F) 
250 275 300 
FIG. 3. Asphalts are hardened by ex- 
posure to gamma _ radiation—softening 
point and penetration change. Note that 
origin of each line is property of unirradi- 
ated sample; broken line denotes blend. 
Numbers show total dose, in 10° r 
performance of a single coating type on 
several surfaces. The differences are 
often striking. For example, the viny] 
coating Amercoat-33, which failed on 
an aluminum panel after 2.4 X 108 1, 
did not fail on a concrete panel until 
1.22  10°r—over five times the gamma 
dose. 
TABLE 3—How Gamma Radiation Affects the Chemical Resistance and Decontaminability of Mounted Coatings 
Gamma Results * 
dose 
Coating Surface (108r) Reagents Acid Base Solvent C/Dt DFt 
Alkaloy-550 Concrete 11.3 HNO;-FP R_ 25-200 
Steel 10 HNOs;, NaOH, hexone R R 
Amercoat-33 Aluminum 1.0 HNO;-FP R_ 70-117 
Amphesive-801 Steel 10 HNO;, NaOH, hexone N N N 
Barrett silicone Concrete 8 HNOs;,-FP R 12 
Steel 8 HNO;, HCl, NaOH, hexone, HNO;-FP N N N N 
Corrosite-22 Aluminum 1.0 HNO;-FP R_ 560 
Duralon-36 Concrete 10 HNO;,-FP R 40-200 
Steel 10 HNO;, NaOH, hexone, HNO;-FP R R N 
Epon-395 Steel 8 HNO;, NaOH, HCl, H2SO,, hexone R R R R200 
Epon-1001 Concrete 12 HNO;,-FP R 5 
Steel 8 HNO:, NaOH, HCl, hexone, HNO;-FP R R N N 
Neobon Steel 10 HNO;, NaOH, hexone, HNO;-FP R R N R_ 3-8 
Nukemite-40 Steel 10 HNO;, NaOH, hexone N N N 
Solar silicone alkyd Concrete 8 HNO;-FP R 8-15 
Steel 8 HNO;-FP N 
* Symbols for results: R = resistant; N = nonresistant. 
+ C/D is the process of HNOs-fission product contamination and decontamination. 
t DF is decontamination factor. 
a 
104 
