Component 2 
Component 4 
re 
Component 3 
Component & 
Zr E, Zr E, Zz E, Z: E, 
ty (cm? /gm) (Mev) ty (cm?/gm) (Mev) ty (cm2/gm) (Mev) 144 (cm2/gm) (Mev) 
80d LX 105¢ 1 5.3y 1 LOm” 1.25 
40d 2.5 1076 0.9 250d 126105 1.12 
13h 7.2 X 1073 0.51 100d 2 X 1076 1 iE 
50h 3.5 X 1077 1.2 140d 5.6 X 1077 VE 
35h 2.3 X 10-6 Let 80d 1.4 X 1075 120 
20h 3.2 X 10-5 0.5 45d one LOR 1.2 5.3y 2.8 X 1075 1.25 
20h 1.0 X 10-4 0.7 60d 4.8 X 10-4 0.74 
12d 1.3 X 1075 0.9 60d Zot L058 1.2 250d 1.9 * 10> 1.12 5.3y 4.4 X 1076 1.25 
15h Lek XX 105° 2.07 50d 1.4 X 1075 We 250d 1-6; < 105° 1.12 5.3y 1S oe LOn 1.25 
15h 5.8 X 107° 2.07 12d 9.7 X 107 0.9 85d 2.0 X 10-8 1 5.3y 4.4 * 1075 1.25 
100d =8 X 107” 1 5.3y LX 1058 1.25 
35h ra xX LORS 1 85d 1.6 X 1078 5.3y 4.4 X 1078 1.25 
70d 1.3 X 107 1 5.3y t.3: 1057 1.25 
12.9-hr Cu® result from positron annihila- TITANIUM hour Zr®’, and 65-day Zr, 
tion, the others are neglected in the analysis Manganese likely contributes the short- 
and the energy taken as 0.51 Mev. The lived activity. The 35-hour component CONCRETE 
Mn** component is quite strong in this may result from the reaction Ti‘8 (n,p)Se48. The components are 2.5-hour Mn®®, 14,.8- 
material. The energy of the 100-day com- The 80-day component is likely 85-day Sc‘ hour Na*4, 12.8-day Bal!4?, 46-day Fes 
ponent was determined from absorption 
measurements. 
LEAD 
The induced activity is relatively low. 
The 2.5-hr component is likely Mn‘*; the 
50-hr component was not identified; the 140- 
day component is likely Ta!8?, 
NIOBIUM 
The greater part of the activity is ac- 
counted for by a tantalum content of 
1.2%. 
from the reaction Ti‘® (n,p)Sc48, 
THORIUM 
The greater part of the activity is 27- 
day Pa?33, 
FERRO-TUNGSTEN 
The components are 2.5-hour Mn®*®, 24- 
hour W!87, 46-day Fe’, and 5.3-year Co®, 
ZIRCONIUM 
The components are 2.5-hour Mn‘, 17- 
(which is included in the 50-60 day compo- 
nent), 250-day Zn, and 5.3-year Co®, 
The 85-day component was not identified. 
The 60-day, 140-day and 250-day compo- 
nents agree respectively with calculated 
values for Fe, Ba and Zn for these materials. 
GRAPHITE 
The 15-hour component is likely 14.8- 
hour Na?4. The 35-hour and 70-100-day 
components are probably mixtures of sev- 
eral components. The 5.3-year component 
is likely Co®, 
* D, = the cross section that gives the total number of photons of all energies. 
t+ E: = the average of the products of the energy of the photon and the number of photons of that energy that are emitted. 
figure is included for use in approximate shielding calculations.) 
(This 
Sample Calculation of Induced Gamma Activity 
A 5-gm thin foil of Inconel has been in the reactor for 80 days at a flux of 10!2 n/cm?/sec. 
will this specimen emit 24 hr after reactor shutdown? 
Substituting values from Table 1 in Eq. 3 
Component 1 (2.5-hr half-life) 
How much gamma radiation 
Component 3 (60-day half-life) 
_ 0.693 X30 X24 _ 0.693 X 24 __ 0.693 X 30 —0.693 X 1 
A = (10")(8.8 X 10-4)(6)(1 —e 25° ye «25 A = (101)(4.8 X 10-9)(5)(1 -e © )e 
= 1.7 X 10° photons/sec = 6.2 X 10" photons/sec 
Component 2 (25-day half-life) Component 4 (5.3-yr half-life) 
__ 0.693 x 30 —0.693 K1 0.693 X 20 —0.693 X 1 
A 
(10'2)(4.1 X 10-5)(5)(1 —e 
1.1 X 108 photons/sec 
Conversion to r/hr 
25 ) e 25 
A = (10")(7.4 X 1074)(5)(1 —e 
5.3 X 365 Je 5.3 X 365 
= 4.0 X 10" photons/sec 
Convert component 3 of the above example to r/hr at 10 cm. 
Here a simple configuration is assumed—a point source. 
photon flux at 10 cm is then 
Substituting in Eq. 4 
4 X 3.14 X 10? 
6.2 X 107 
The area over which the photons are distributed is 4mr*. 
The 
= 4.9 X 104 photon/cm?/sec 
rfhr = (4.9 X 104)(1.2)(0.058)(3.5 X 10-5) = 0.11 
