検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年

JENDL-4.0 benchmark for high temperature gas-cooled reactor, HTTR

JENDL-4.0の高温ガス炉(HTTR)ベンチマーク

後藤 実; 島川 聡司; 安元 孝志*

Goto, Minoru; Shimakawa, Satoshi; Yasumoto, Takashi*

過去にIAEAにおいて高温ガス炉(HTTR)の臨界近接試験の国際ベンチマーク計算が行われ、その多くは過剰反応度を過大評価した。原子力機構(JAEA)のベンチマーク計算も、他の場合と同様に過剰反応度を過大評価する結果となった。その後、幾何形状モデルの見直しや当時最新の核データライブラリJENDL-3.3の利用により、JAEAの計算結果は改善されたが、過大評価の問題は残った。一方、異なる核データライブラリを用いたHTTRの炉心計算の比較により、ライブラリ間の熱領域における炭素の捕獲断面積のわずかな違いが、計算結果に有意な違いをもたらすことがわかった。この断面積の値はミリバーンのオーダーで小さいため、原子炉の核計算分野における関心は低く、その結果、JENDL, ENDF/B、及びJEFFといったメジャーな核データライブラリでさえ、その値は長い間見直されてこなかった。われわれは、HTTRの炉心計算の精度向上の観点から、この断面積を最新の測定値に基づき見直す必要があると考えていた。2010年5月、JENDLの最新版(JENDL-4)がJAEAより公開され、熱領域の炭素の捕獲断面積が最新の測定値に基づき見直された。その結果、JENDL-4を用いたHTTRの臨界近接試験の計算は、JENDL-3.3を用いた場合に比べて実効増倍率を0.4%$$Delta$$kから0.9%$$Delta$$k小さく評価し、従来の過剰反応度を過大評価する問題が解決された。

In the past, benchmark calculations of the HTTR criticality approach, which is a Japanese HTGR, have been performed by several countries, and almost of the calculations have overestimated its excess reactivity. In Japan, the benchmark calculations were performed by JAEA, and the calculations also resulted in overestimation. JAEA improved this overestimation by revising the problem geometry and replacing nuclear data library with JENDL-3.3, which was the latest JENDL at that time. However, the overestimation remained and this problem had not been resolved until today. We performed the calculation of the HTTR criticality approach with several nuclear data libraries, and found the slightly difference of the capture cross section of carbon at thermal energy among the libraries causes the difference of the $$k$$$$_{eff}$$ values to be not negligible. This cross section value had not been concerned in reactor neutronics calculation because of its small value on the order of 10$$^{-3}$$ burn, and consequently the cross section value had not been revised for a long time even in the major nuclear data libraries: JENDL, ENDF/B and JEFF. We have thought the cross section value should be revised based on the latest measurement data to improve the accuracy of the neutronics calculations for HTTR. On May in 2010, the latest JENDL (JENDL-4) was released by JAEA, and the capture cross section of carbon was revised. Consequently, JENDL-4 yielded 0.4-0.9%$$Delta$$k smaller $$k$$$$_{eff}$$ values than JENDL-3.3 in the calculation for the HTTR critical approach, and then the problem of the overestimation of the excess reactivity in the HTTR benchmark calculation was resolved.

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.