2 Subcriticality
15
1
2
3
4
5
6
7
8
9
1 0
1 1 1 2 1 3
1 4 1 5 1 6 1 7 1 8 1 9
2 0 2 1 2 2 2 3
A
G r G r G r G r
G r G r G r G r G r G r
G r G r G r G r G r G r
G r G r G r G r
F
B
G r
G r
G r
G r
C
G r
G r
G r
G r
4
D
G r
G r
G r
G r
E
G r
p
p
G r
G r
p
p
p
G r
p
F
Gr
p
p
p
Gr
Gr
p
p
p
Gr
G G r
p
p
p
p
p
p
p
p
p
p
p
G r
H
G r
p
p
p
p
p
p
p
p
p
p
p
G r
I
G r
p
p
p
p
4
p
p
p
p
Gr
Gr
J
G r
p
p
p
F
F
F
F
F
p
p
p
G r
K
G r
p
p
F
F
F
F
F
p
p
G r
L
G r
p
p
F
F
F
F
F
p
p
p
G r
M G r
p
p
p
F
F
F
F
F
p
p
p
G r
N
G r
p
p
F
F
F
F
F
p
p
G r
O G r
p
p
p
p
p
p
p
p
p
p
p
G r
P
G r
p
p
p
p
p
p
p
p
p
p
G r
Q G r
p
p
p
p
p
p
p
p
p
p
G r
R
G r
Gr
S
G r
Gr
T
G r
Gr
U
G r
Gr
V
G r G r G r G r
G r G r G r G r G r G r
G r G r G r
G r G r G r G r G r G r
G r G r G r G r
Normal fuel (1/8"p60EUEU)
Graphite
Partial fuel (1/8"p4EUEU)
Aluminum sheath
Polyethylene moderator
Polyethylene reflector
Control rod
Safety rod
Neutron source (Am-Be)
Fission chamber
Uncompensted ionization chamber
1"φ hole polyethylene
Pb-Bi target
N
FC
UIC
S
C
C3
S5
S4
C1
C2
S6
N
FC#1
UIC#4
FC#2
UIC#5
UIC#6
BF-3 detector #1
BF-3 detector #2
BF-3 detector #3
BF-3 detector #4
FC#3
Fig. 2.2 Top view of core configuration and neutron detector location (Ref. [1])
Table 2.1 Experimental patterns of control rods and central fuel loading (Ref. [1])
Subcritical Axial position [mm]
Central
Subcriticality
Pattern
C1
C2
C3
S4
S5
S6
Loading [%k/k]
Critical
U.L. 678.98 U.L. U.L. U.L. U.L. C.I.
A
U.L. L.L.
U.L. U.L. U.L. U.L. C.I.
0.307 ± 0.008
B
L.L.
U.L.
U.L. U.L. U.L. U.L. C.I.
0.725 ± 0.018
C
L.L.
L.L.
L.L.
U.L. U.L. U.L. C.I.
1.483 ± 0.040
D
L.L.
L.L.
L.L.
U.L. U.L. L.L.
C.I.
2.056 ± 0.054
E
L.L.
L.L.
L.L.
L.L.
L.L.
L.L.
C.I.
3.189 ± 0.083
F
L.L.
L.L.
L.L.
L.L.
L.L.
L.L.
C.W.
13.604 ± 0.381
L.L.: Lower Limit [0 mm], U.L.: Upper Limit [1200 mm]
C.I.: Completely Inserted, C.W.: Completely Withdrawn
2.1.1.2 Experimental Conditions
Four BF 3 proportional neutron counters (LND-202101, 1” dia., 15.47” len.) were
used for the present experiment. These BF3 counters on locations (Q, 12), (P, 8),
(L, 7), and (E, 8) are referred to as B1, B2, B3, and B4, respectively. The axial
center of effective length of these counters was located at the axial center position
15
1
2
3
4
5
6
7
8
9
1 0
1 1 1 2 1 3
1 4 1 5 1 6 1 7 1 8 1 9
2 0 2 1 2 2 2 3
A
G r G r G r G r
G r G r G r G r G r G r
G r G r G r G r G r G r
G r G r G r G r
F
B
G r
G r
G r
G r
C
G r
G r
G r
G r
4
D
G r
G r
G r
G r
E
G r
p
p
G r
G r
p
p
p
G r
p
F
Gr
p
p
p
Gr
Gr
p
p
p
Gr
G G r
p
p
p
p
p
p
p
p
p
p
p
G r
H
G r
p
p
p
p
p
p
p
p
p
p
p
G r
I
G r
p
p
p
p
4
p
p
p
p
Gr
Gr
J
G r
p
p
p
F
F
F
F
F
p
p
p
G r
K
G r
p
p
F
F
F
F
F
p
p
G r
L
G r
p
p
F
F
F
F
F
p
p
p
G r
M G r
p
p
p
F
F
F
F
F
p
p
p
G r
N
G r
p
p
F
F
F
F
F
p
p
G r
O G r
p
p
p
p
p
p
p
p
p
p
p
G r
P
G r
p
p
p
p
p
p
p
p
p
p
G r
Q G r
p
p
p
p
p
p
p
p
p
p
G r
R
G r
Gr
S
G r
Gr
T
G r
Gr
U
G r
Gr
V
G r G r G r G r
G r G r G r G r G r G r
G r G r G r
G r G r G r G r G r G r
G r G r G r G r
Normal fuel (1/8"p60EUEU)
Graphite
Partial fuel (1/8"p4EUEU)
Aluminum sheath
Polyethylene moderator
Polyethylene reflector
Control rod
Safety rod
Neutron source (Am-Be)
Fission chamber
Uncompensted ionization chamber
1"φ hole polyethylene
Pb-Bi target
N
FC
UIC
S
C
C3
S5
S4
C1
C2
S6
N
FC#1
UIC#4
FC#2
UIC#5
UIC#6
BF-3 detector #1
BF-3 detector #2
BF-3 detector #3
BF-3 detector #4
FC#3
Fig. 2.2 Top view of core configuration and neutron detector location (Ref. [1])
Table 2.1 Experimental patterns of control rods and central fuel loading (Ref. [1])
Subcritical Axial position [mm]
Central
Subcriticality
Pattern
C1
C2
C3
S4
S5
S6
Loading [%k/k]
Critical
U.L. 678.98 U.L. U.L. U.L. U.L. C.I.
A
U.L. L.L.
U.L. U.L. U.L. U.L. C.I.
0.307 ± 0.008
B
L.L.
U.L.
U.L. U.L. U.L. U.L. C.I.
0.725 ± 0.018
C
L.L.
L.L.
L.L.
U.L. U.L. U.L. C.I.
1.483 ± 0.040
D
L.L.
L.L.
L.L.
U.L. U.L. L.L.
C.I.
2.056 ± 0.054
E
L.L.
L.L.
L.L.
L.L.
L.L.
L.L.
C.I.
3.189 ± 0.083
F
L.L.
L.L.
L.L.
L.L.
L.L.
L.L.
C.W.
13.604 ± 0.381
L.L.: Lower Limit [0 mm], U.L.: Upper Limit [1200 mm]
C.I.: Completely Inserted, C.W.: Completely Withdrawn
2.1.1.2 Experimental Conditions
Four BF 3 proportional neutron counters (LND-202101, 1” dia., 15.47” len.) were
used for the present experiment. These BF3 counters on locations (Q, 12), (P, 8),
(L, 7), and (E, 8) are referred to as B1, B2, B3, and B4, respectively. The axial
center of effective length of these counters was located at the axial center position