検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年

核計算コードWIMS-ATRの精度向上

Improvement of calculational accuracy of coolant void reactivity by using WIMS-ATR code

福村 信男*; 川太 徳夫*; 小綿 泰樹*

not registered; not registered; not registered

(目 的)ATR実証炉の核設計に用いられている核計算コードWIMS-ATRの精度向上の一環として冷却材ボイド反応度の解析精度の向上を、拡散係数の導出手法を詳細化することにより達成する。(方 法)WIMS-ATRコードに組み込まれている拡散係数導出手法は、格子内を3領域のみに分割し衝突確率を求めBonalmiの理論にもとずき導出しているが、この場合の衝突確率を定義式にもとずき領域毎に正確に解き拡散係数を導出する。(結 果)正確な手法により求めた拡散係数を用い、DCA臨界実験の結果および「ふげん」起動試験時の結果について検証したところ下記の結果が得られた。(1) 拡散係数の値は従来の手法に比べ大きくなり、特に高ボイド率および高速群で顕著である。(2) 冷却材ボイド反応度の核計算誤差は、DCA体系で0.2%$$Delta$$k、「ふげん」の起動試験体系で、0.07%$$Delta$$kとなり改良前の約1/2となった。(結 論)拡散係数の導出手法を正確に行うことにより、体系からの漏洩効果を精度よく評価することが可能となり、これにより冷却材ボイド反応度の計算精度が大幅に向上した。

Improvement of calculational accuracy of ATR coolant void reactivity has been tried by using the more detailed calculational method as for the derivation of diffusion constant. The former calculational method of deriving the diffusion constant in WIMS-ATR code is the followings: (1)Calculation of collision probability with use of the model dividing the cell into three region (fuel, air gap and moderator). (2)Calculation of diffusion constant according to Bonalmi theory with use of the above calculated collision probability values. The present method is the one which calculates the collision probability more accurately by using multi region model including fuel, coolant, pressure tube and so on. For calculation of collision probability the CLUP code was used. By using the present code with the new calculational model of diffusion constant the coolant void reactivity were calculated. The following results were obtained: (1)The value of the diffusion constant is larger than the former one. This fact is more remarkable in the high voidage core and in the fast neutron energy region. (2)The present calculation accuracies of coolant void reactivity are 0.2%$$Delta$$k for the DCA core and 0.07%$$Delta$$k for the FUGEN core. These values are a half of the former ones. From the above results it is concluded that the present calculation model of the diffusion constant is effective for improvement of calculational accuracy of coolant void reactivity in ATR.

Access

:

- Accesses

InCites™

:

Altmetrics

:

[CLARIVATE ANALYTICS], [WEB OF SCIENCE], [HIGHLY CITED PAPER & CUP LOGO] and [HOT PAPER & FIRE LOGO] are trademarks of Clarivate Analytics, and/or its affiliated company or companies, and used herein by permission and/or license.