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JAEA-Conf 2011-002 - 日本原子力研究開発機構

JAEA-Conf 2011-002 - 日本原子力研究開発機構

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fuel columns, respectively. These libraries underestimate the loaded number of the fuel columns<br />

by one or two columns, which are caused by the overestimation of the keff value.<br />

The discrepancy of the loaded number of the fuel columns achieving the first criticality<br />

between the experiment and the calculations was resolved by replacing the nuclear data<br />

libraries with JENDL-4.0.<br />

3.2 Excess reactivity of fully loaded core<br />

The excess reactivity of the fully loaded core ex, is defined by<br />

keff<br />

1<br />

ex<br />

. (1)<br />

keff<br />

Table 2 shows that JENDL-4.0 yields the excess reactivity of 12.0%k/k, which agrees well with<br />

the experimental result. Meanwhile, JENDL-3.3, ENDF/B-VII.0 and JEFF-3.1 give the excess<br />

reactivity of 12.4, 12.8 and 12.7%k/k, and they overestimates by 0.4-0.8%k/k.<br />

The problem of overestimating the excess reactivity at the fully loaded core was also<br />

resolved by replacing the nuclear data libraries with JENDL-4.0.<br />

Table 2 Comparisons between experimental[10] and calculation results<br />

Number of fuel columns<br />

achieving the first criticality<br />

Excess reactivity of the fully<br />

loaded core (%k/k)<br />

<strong>JAEA</strong>-<strong>Conf</strong> <strong>2011</strong>-<strong>002</strong><br />

Experiment JENDL-4.0 JENDL-3.3 ENDF/B-VII.0 JEFF-3.1<br />

19 19 18 17 17<br />

12.0 12.0 12.4 12.8 12.7<br />

4. Conclusions<br />

The criticality calculations of 12-30 fuel columns loaded core, which were constructed in<br />

the critical approach, were performed with JENDL-4.0, JENDL-3.3, ENDF/B-VII.0, and<br />

JEFF-3.1. As a result, JENDL-4.0 yields keff values which are 0.5-0.9%k smaller than<br />

JENDL-3.3, and 1.0-1.5%k smaller than ENDFL/B-VII.0 or JEFF-3.1. The keff values<br />

calculated with ENDF/B-VII.0 and JEFF-3.1 are the same within 2 for the all core states.<br />

The discrepancies between the experimental and the calculation results on the following<br />

two issues were resolved as expected by replacing the nuclear data libraries with JENDL-4.0.<br />

This fact shows that the applicability of JENDL-4.0 to the HTTR criticality calculations is more<br />

excellent than the other nuclear data libraries.<br />

(a) The loaded number of fuel columns achieving the first criticality.<br />

(b) Excess reactivity of the fully loaded fuel columns core.<br />

JENDL-4.0 promises to improve the accuracy of the HTGR criticality calculations, which<br />

allows the design of the commercial HTGR with lower cost and higher performance.

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