JAEA-Conf 2011-002 - 日本原子力研究開発機構

ENDF. Thus this cross section stored in ENDF has not been revised more than 36 years at least.
The cross section of JEFF-3.1 was taken from ENDF/B-VI.8[7], and it evaluated based on as old
measurement data as ENDF.
Table 1 Neutron capture cross section of carbon at 0.0253eV
JENDL-4.0 JENDL-3.3 ENDF/B-VII.0 JEFF-3.1
3.85mb 3.53mb 3.36mb 3.36mb
2.4 Calculation conditions and method
The criticality calculations for the 12-30 fuel columns loaded core with all control rods
withdrawn at room temperature were performed with the continuous energy Monte Carlo code
MVP[8] to obtain the keff value for each core state. The core geometry was treated as much
detail as possible, and a heterogeneous effect caused by a coated fuel particle was taken into
account by using a Statistical Geometry (STG) model[9]. The history number was defined
8,000,000 for each calculation to reduce the standard deviation (1) to about 0.03%.
3. Results and discussion
Figure 3 shows calculated keff
curves for the several HTTR core 1.15
states, which were configured in
JENDL-4.0
JENDL-3.3
the critical approach. JENDL-4.0
yields the keff values which are
1.10
ENDF/B-VII.0
JEFF-3.1
smaller than the other libraries for
Excess reactivity
the all core states. Specifically, the
1.05
for fully loaded core
keff values
JENDL-4.0
calculated with
are 0.5-0.9%k 1.00
k = 1 eff
smaller than JENDL-3.3, and are
First criticality
1.0-1.5%k smaller than
ENDFL/B-VII.0 or JEFF-3.1. The
keff values calculated with
0.95
12 14 16 18 20 22 24
Number of loaded fuel column
26 28 30
ENDF/B-VII.0 and JEFF-3.1 are
the same within 2 for the each core states.
Fig. 3 keff curves for each core states
k eff
JAEA-Conf 2011-002
3.1 Loaded number of fuel columns achieving first criticality
The loaded number of the fuel columns at the first criticality is determined by
identifying the first column with which the keff value is more than 1.0. Thus, the keff curve with
JENDL-4.0 indicates that the first criticality is achieved by loading 19 fuel columns, which
agrees with the experimental result. Meanwhile, the keff curves with JENDL-3.3,
ENDF/B-VII.0 and JEFF-3.1 indicate the first criticality is achieved by loading 18, 17, and 17