10 years of cooling time after irradiation was assumed in these analyses. The flux
intensities at the center, top, and bottom in the axial direction are shown in
Table 20.4. The flux intensity at the center corresponds to the average power in
typical BWR fuel assemblies. The flux intensities at the top and bottom were
Table 20.2 (continued)
Specification (wt%)
Value in analysis (wt%)
Mo
0.005
Max.
0.005
Cd
0.00005
Max.
0.00005
Sn
1.20
–
1.70
1.45
Hf
0.01
Max.
0.01
W
0.01
Max.
0.01
U
0.00035
Max.
0.00035
(c) SUS304 stainless steel (JIS G 4303)
C
0.08
Max.
0.08
Si
1.00
Max.
1.00
P
0.045
Max.
0.05
S
0.030
Max.
0.03
Cr
18.00
–
20.00
19.00
Mn
2.00
Max.
2.00
Fe
Balance
68.595
Ni
8.00
–
10.50
9.25
(d) INCONEL alloy 718 (UNS N07718)
B
0.006
Max.
0.006
C
0.08
Max.
0.08
Al
0.20
–
0.80
0.50
Si
0.35
Max.
0.35
P
0.015
Max.
0.015
S
0.015
Max.
0.015
Ti
0.65
–
1.15
0.90
Cr
17.00
–
21.00
19.00
Mn
0.35
Max.
0.35
Fe
Balance
16.809
Co
1.00
Max.
1.00
Ni
50.00
–
55.00
52.50
Cu
0.3
Max.
0.30
Nb
4.75
–
5.50
5.125
Mo
2.80
–
3.30
3.05
Table 20.3 Cross-section libraries
Specification in cross-section library
Cladding tubes, spacers, channel boxes
BWR STEP-III, void ratio 40 %
Top-end-plugs
BWR STEP-III, void ratio 70 %
Bottom-end-plugs
BWR STEP-III, void ratio 0 %
20 Sensitivity Analyses of Initial Compositions and Cross Sections. . .
237