238
M. Yamanaka
10
-3
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
6
10
7
-0.040
0
0.040
0.080
0.120
0.160
0
0.20
0.40
0.60
0.80
1.00
Neutron energy [eV]
Sensitivity per unit lethargy [-]
EE1 (1/8"P60EUEU)
E3 (3/8"P36EU)
Standard deviation
Standard deviation [%]
EE1
E3
Standard deviation
Fig. 8.10 Sensitivity profile and standard deviation covariance data for H (n, n) reactions
(polyethylene) (Ref. [2])
10
-3
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
6
10
7
-0.100
-0.080
-0.060
-0.040
-0.020
0
0
2
4
6
8
10
12
14
Neutron energy [eV]
Sensitivity per unit lethargy [-]
EE1 (1/8"P60EUEU)
E3 (3/8"P36EU)
Standard deviation
Standard deviation [%]
E3
EE1
Standard deviation
Fig. 8.11 Sensitivity profile and standard deviation in covariance data for H (n, γ ) reactions
(polyethylene) (Ref. [2])
8.3.2.4 Reproducibility of Control Rod Position
The uncertainty induced by the reproducibility of control rod positions, as shown in
Tables 8.14 and 8.15, indicated about 3 pcm even at the withdrawal (no insertion)
of control rods in Cases I-1 and II-1, showing an index of accuracy induced by the
approximation in Eq. (8.20). By considering the index from the control rod insertion
pattern, the uncertainty attributed to varying control rod position was evaluated about
8 pcm depending slightly on the insertion pattern. Here, the evaluated uncertainty was
nearly the same as the experimental uncertainty in the reactivity shown in Tables 8.10