Annual Report 2009/2010 - JUWEL - Forschungszentrum Jülich

Tab. 23: Results for the determination of the Cs-137 activity in the investigated radioactive
waste drums by the conventional and improved method. The true activity is the sum
of the sources activities. The activity is given at the time of the measurement.
Drum
Nr.
Cs-137 Activity in Bq
Waste True activity Conventional
g/cm 3
density
method
1 3.99 4.68 10 10 0 . 59 8
1.
480.
59
10
2 2.94 6.59 10 10 0 . 22 9
1.
420 . 22
10
3 3.64 1.73 10 10 2 . 98 6
8.
082 . 98
10
4 2.63 7.49 10 9 0 , 94 7
6.
700 . 94
10
5 2.61 3.46 10 11 0 . 29 8
1.
690.
29
10
6 3.47 1.58 10 11 0 . 46 8
4.
400.
46
10
7 3.48 9.08 10 10 0 . 12 9
1.
160 . 12
10
8 3.66 4.48 10 11 0,
81 8
4.
870 . 81
10
9 4.04 9.86 10 10 0 10 7
3 03
.
.
0.
10
10
10 3.57 6.99 10 10 0 . 04 7
1.
290 . 04
10
11 2.68 2.02 10 10 0 . 35 9
4.
120.
35
10
12 2.71 2.93 10 12 1 . 12 8
4.
77
1.
12
10
13 3.61 3.83 10 11 0 . 53 7
3.
880 . 53
10
Total 4.68 10 12 1 . 04 9
8.
58
1.
04
10
Homogeneous
matrix
0,
58 9
2.
650 , 58
10
1 61 10
1 81
.
.
1.
61
10
2.
51 8
2.
27
1.
20
10
12.
67 8
7.
974.
86
10
2.
10 9
2.
192 . 10
10
5.
06 10
3.
492.
06
10
13.
56 10
7.
494 . 79
10
1.
58 10
2.
05
1.
58
10
1.
54 9
7.
34
1.
54
10
0.
66 9
1.
840 . 66
10
1 54 10
7 71
.
.
1.
54
10
3.
74 9
7.
483 . 94
10
5.
37 9
5.
545 . 37
10
2 08 11
2 53
.
.
1.
27
10
Improved method
Heterogeneous matrix
0.
94 10
4.
270 . 94
10
5.
41 10
6.
085.
41
10
8.
10 9
7.
303 . 87
10
15.
39 9
9.
685 . 90
10
1.
06 11
1.
10
1.
06
10
6.
58 11
4.
542.
68
10
17.
38 11
9.
606.
14
10
1.
28 11
1.
67
1.
28
10
1.
38 10
6.
57
1.
38
10
0,
54 10
1.
500 , 54
10
0.
79 11
3.
950 , 79
10
0.
52 11
1.
040 , 52
10
3.
14 10
3.
243 . 14
10
2.
75 12
2.
42
1.
36
10
10 1
10 2 Cs-137
Co-60
Mean of A calculated
/A true
10 0
10 -1
10 -2
10 -3
10 -4
Conventional
Improved
(Homogeneous matrix)
Improved
(Heterogeneous matrix)
Method
Fig. 93: Mean ratio of the calculated to true activity for the different methods applied.
The conventional method leads to a large underestimation of the activity since the nonuniform
distribution of the isotopes and the shielding structures inside the drums are not
considered. The mean factor of underestimation is 586 for Cs-137 and 16 for Co-60. The
127