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Target Nuclides of Sensitivity Analyses

The representative radioactive nuclides in this study (Table 20.5) include not only the important nuclides for various evaluations of radioactive wastes but also the nuclides whose concentrations have been measured in the past, which will be useful for the validation of numerical evaluations.

Target nuclides of sensitivity analyses were selected on the basis of two criteria. The first was that the concentrations of activation products be larger than or comparable to the concentration of fission products generated from impurity uranium in the materials. The contents of impurity uranium in Zircaloy-2 and SUS304 stainless steel were 0.00035 wt% and 0.0001 wt% [5], respectively. This value in INCONEL alloy is unknown. The second criterion was that the concentrations of activation products be comparatively large. In these analyses, activation products with concentrations more than 1 x 10-9 g/t were chosen.

The concentrations of activation products larger than 1 x 10-9 g/t and fission products generated from impurity uranium are shown in Table 20.6. The fission products were calculated under the condition that the initial composition contains

only the uranium impurity. Table 20.6 also shows the selected target nuclides that satisfy the foregoing criterion: 17 nuclides in Zircaloy-2 and Zircaloy-4, 8 nuclides in SUS304 stainless steel, and 16 nuclides in INCONEL alloy were selected as the target nuclides of sensitivity analyses.

Table 20.5 Representative radioactive nuclidesa,b

No.

Nuclide

Half-life

No.

Nuclide

Half-life

No.

Nuclide

Half-life

1

H-3

12.3

years

21

Se-79

377.0

E3 years

41

Cs-137

30.1

years

2

Be-10

1.5

E6 years

22

Rb-87

48.1

E9 years

42

Ba-133

10.5

years

3

C-14

5.7

E3 years

23

Sr-90

28.8

years

43

Sn-126

198.0

E3 years

4

Na-22

2.6

years

24

Nb-94

20.3

E3 years

44

Sb-124

60.2

days

5

Si-32

153.0

years

25

Nb-95

35.0

days

45

Sb-125

2.8

years

6

S-35

87.5

days

26

Mo-93

4.0

E3 years

46

Ce-141

32.5

days

7

Cl-36

301.0

E3 years

27

Mo-99

2.7

days

47

Ce-144

284.9

days

8

K-40

1.2

E9 years

28

Tc-99

211.1

E3 years

48

Eu-152

13.5

years

9

Sc-46

83.8

days

29

Tc-99m

6.0

hours

49

Eu-154

8.6

years

10

Ca-41

102.0

E3 years

30

Zr-93

1.5

E6 years

50

Eu-155

4.8

years

11

Cr-51

27.7

days

31

Zr-95

64.0

days

51

Gd-153

240.4

days

12

Mn-54

312.1

days

32

Ru-103

39.3

days

52

Ho-166m

1.2

E3 years

13

Fe-55

2.7

years

33

Ru-106

1.0

years

53

Hf-181

42.4

days

14

Fe-59

44.5

days

34

Ag-108m

438.0

years

54

Au-199

3.1

days

15

Co-57

271.7

daysc

35

Ag-110m

249.8

days

16

Co-58

70.9

days

36

I-129

15.7

E6 years

17

Co-60

5.3

years

37

Cd-113m

14.1

years

18

Ni-59

76.0

E3 years

38

I-131

8.0

days

19

Ni-63

100.1

years

39

Cs-134

2.1

years

20

Zn-65

244.1

days

40

Cs-135

2.3

E6 years

aHalf-life is referred to ORLIBJ40 decay library

bE3 years ¼ 103 years, E6 years ¼ 106 years

cHalf-life of Co-57 is not contained in ORLIBJ40, so it is referred to [4]

Table 20.6 Concentration of activation products and fission products

Nuclide

Concentration of activation products (g/t)

Concentration of fission products (g/t)

Comparison (%)

Target nuclide

①Zry-2

②Zry-4

③/(①+③)

(a) Zircaloy-2 and Zircaloy-4

Zr-93

2.0E + 02

2.0E + 02

1.2E-03

0

Ni-59

3.7E + 00

4.7E-01

Ni-63

6.6E-01

8.9E-02

Co-60

5.1E-01

5.1E-01

C-14

4.0E-01

4.0E-01

Nb-94

3.0E-01

3.0E-01

3.2E-09

0

Sb-125

2.5E-01

2.5E-01

1.5E-06

0

Ca-41

3.0E-02

3.0E-02

K-40

2.2E-02

2.2E-02

Fe-55

2.1E-02

3.2E-02

Tc-99

9.1E-03

9.1E-03

1.7E-03

16

Mo-93

8.9E-03

8.9E-03

3.5E-14

0

Be-10

4.0E-05

4.0E-05

2.2E-08

0

Sr-90

2.3E-05

2.3E-05

6.0E-04

96

Mn-54

3.9E-06

6.1E-06

Ag108m

3.3E-07

3.3E-07

5.6E-12

0

Rb-87

1.1E-07

1.1E-07

3.7E-04

100

H-3

3.0E-08

3.0E-08

5.8E-08

66

I-129

6.4E-09

6.4E-09

3.9E-04

100

Zn-65

2.8E-09

2.8E-09

(b) SUS304 stainless steel

Nuclide

Concentration of activation products (g/t)

Concentration of fission products (g/t)

Comparison (%)

Target nuclide

①Bottom

②Top

③/(①+③)

Ni-59

4.8E + 01

2.6E + 01

Ni-63

7.7E + 00

4.1E + 00

Fe-55

7.0E-01

3.9E-01

Co-60

5.3E-03

5.0E-03

Mn-54

9.9E-05

9.9E-05

Be-10

5.7E-06

5.7E-06

2.0E-10

0

C-14

3.2E-06

2.3E-06

Cl-36

1.6E-06

4.4E-07

Table 20.6 (continued)(c) INCONEL alloy 718

Nuclide

Concentration of activation products (g/t)

Target nuclide

Ni-59

3.5E + 03

Ni-63

6.2E + 02

Co-60

2.6E + 02

Nb-94

1.6E + 02

Mo-93

5.4E + 00

Tc-99

5.4E + 00

Fe-55

3.4E + 00

Zr-93

1.3E-01

Mn-54

4.8E-04

Be-10

2.8E-04

Cl-36

1.7E-04

C-14

5.4E-05

Zn-65

1.7E-07

Sr-90

1.3E-08

Si-32

7.9E-09

H-3

1.8E-09

 
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