Activity in Some Common Structural Materials 
Component 2 Component 3 Component 4 Component 6 
zy E, Zz E, Zz E, De E, 
ty (cm?/gm) (Mev) tig (cm?/gm) (Mev) ty (cm?/gm) (Mev) lig (cm?/gm) (Mev) 
45d Sele Oe> 12 5.3y 5.0 X 1075 1,25 
45d 2.6 X 1075 1.2 5.3y 6.4 X 1075 1.25 
45d 3.0 LO 1.2 5.3y 4.6 X 107° 1.25 
45d 3.0 o6 1055 1.2 5.3y 4.6 X 10-5 1.25 
45d 3.0 < 10° 1.2 5.3y eo alee 1.25 
45d 3.3 X 1075 1.2 5.3y 4.6 X 1075 1.25 
60d 4X 10-5 0.8 5.3y 8.0 X 1073 1.25 
60h 1.8 X 1074 0.3 60d 3 X 10-5 1 5.3y o2Or x 10s 1.25 
60h 15) >< 1O=* 0.3 60d 2.2 X 1075 1 5:3y 20 10-3 1.25 
60h 6 X 1075 0.3 25d 8.5 X 10-5 0.32 60d Ux 105 1 5.3y 9.5 X 10-4 1,25 
13h 5.2 & 10-4 0.51 60d 319 LO 1.2 5.3y 329 X< 10-4 1.25 
25d Aye x<a Oa2 0.32 60d 4.3: < 1075 1.2 5.3y 7.4 X 1074 1,25 
25d 5 X 1075 0.32 60d 5.0 * 107° 1.2 115d 9.2 X 10-5 2 5.3y €X104 1.25 
13h 2.7 X 10% 0.51 60d 2.7 X 10°5 1.2 5.3y 2.1 X 1073 1,25 
15h 254-1074 0.51 25d 5.5 X 1075 0.32 45d 3.9 X 1075 1.2 5.3y T2105 1.25 
25d 7.4 xX 10° 0.32 45d 3.0 Ko LOE? 1.2 5.3y 6.2 X 1074 1.25 
25d (74 LOS 0.32 45d 3.6 X 1075 1.2 5.3y 6.0 XK 1074 125 
25d 5.5 X 1075 0.32 45d 3.6 X 10~° ihe 4 5. 3y 5n0) Se 10m 1.25 
25d 8.2 K 1075 0.32 45d 3.6 X 1075 1.2 120d 3.5 X 105 1.2 5.3y 8.3 X 10-4 1.25 
25d 9.8 X 10°° 0.32 45d 3.8 X 10-5 1.2 5.3y li 1052 1.25 
25d 8.5 xX 10-5 0.32 45d Soe LO 1.2 5.3y dea 105" 1.25 
25d 9.6 X 10-5 0.32 45d 320 1052 1.2 5.3y Shoal Om 1.25 
25d 9.6 X 1075 0.32 45d 20 6 10 1.2 120d 229 > 10-5 1.2 5.3y 6.l xX 104 1 25 
25d 6.6 X 107° 0.32 45d ome eel Os 1.2 5.3y 124 10 1.25 
25d 5.5 X 10-5 0.32 45d 3.5 X 1075 1.2 5.3y 1.3 <X 1074 1.25 
25d 5.5 X 107° 0.32 45d 2a LOs? 1.2 5.3y 1.9 <X 1054 1.25 
25d 7.3 X 107° 0.32 45d 2.7 X 107° 1.2 5.3y 1.1 XxX 10-4 1.25 
25d 5.7 X 1075 0.32 45d 3.5 & 107-5 172 5.3y Zl X 1054 1.25 
25d 1.2 X 107-4 0.32 45d Py tay >< MOO 1.2 5.3y 1 AX 1054 1.25 
25d 1.6 X 1075 0.32 45d 3.2 X 10-5 1.2 5.3y 6:0) 105° 1.25 
15h 8.4 X 1076 2.07 130d 12 xX 1057 1.2 5.3y 5 X 1077 1.25 
15h 5.7 x 105® 2.07 45d 2.1 <X 1077 1.2 5.3y 1.4 xX 107° 1.25 
15h 5.7 X 107° 2.07 120d 1.4 K 1077 1.2 5.3y 4x 1077 1.25 
15h 9.8 x 107° 2.07 250d 13% 1055 1.12 
The activity component remaining after 
subtracting the shorter lived components 
was taken as 5.3-year Co® and is accounted 
for by a cobalt content of 0.01 to 0.05 % for 
the various alloys. In 410 and 400 stainless 
steels the presence of enough cobalt to 
account for the 5.3-year activity was con- 
firmed by chemical analysis. This identity 
agrees with the average energy of the 
gamma radiation, about 1.0 to 1.2 Mev. 
NICKEL ALLOYS 
Since the 2.5-hour component was only 
about 10% of the total activity of the 
nickel sample at the time decay measure- 
ments were begun, the accuracy of resolu- 
tion of this component is not better than 
50%. This measured activity, from Ni® 
(n,y) Nis*, did not check the calculated 
activity—the calculated value being about 
3 times too large. The 2.5-hour activity 
for the nickel alloys is from Mn‘6, 
The 60-70 day component is probably 
from the Nis (n,p)Co* reaction. After 27 
hours decay time the ion chamber response 
for the nickel sample is about 40% from 
the 60-70 day Co** and 60% from the 
5.3-year Co. The average value of 
gamma energy is 1.25 Mev for Co® and 0.80 
Mev for Co‘; this gives an average energy 
for the nickel of 0.4 X 0.80 + 0.6 X 1.25 
= 1.07 Mev, in good agreement with the 
value from absorption measurements, 1.1 
+ 0.1 Mev. 
Other activities are due to 26.5-day 
Cr*!, 67-hour Mo®, and 12.8-hr Cu*4, The 
46-day Fe*® activity is not resolvable from 
the 60—70-day Co** in the 60-day component 
by the present analysis, therefore the two 
are combined in Table 1. 
STAINLESS STEELS 
The 2.5-hour activity is 2.59-hour Mn®é, 
the 46-day activity to 46-day Fe‘, and the 
5.3-year activity is Co® as discussed for 
the iron and nickel alloys. The 25-day ac- 
tivity is due to 26.5-day Cr*!, The 120-day 
activity is due to 113-day Ta!*? from the 
tantalum present in the niobium stabilizer 
in the 309 and 347 alloys. 
ALUMINUM ALLOYS 
The 2.5-hour activity is from Mn. The 
15-hour component is due to the Al?7 
(n,a)Na?4 reaction. The 250-day Zn‘ 
activity in 72S aluminum agrees with the 
calculated value based on 1% Zn. The 45- 
day component in 3S aluminum may be 
accounted for by about 0.56% iron. 5 ppm 
tantalum and 1 ppm cobalt may account 
for the other activities. 
75 
