核設計基本データベースの整備 -最新手法によるJUPITER-I実験解析-

Development of a standard data base for FBR core nuclear design; Analysis of JUPITER-I Experiments by the latest method

核設計DB W*

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大型FBR炉心のための核設計基本データベース整備の一環として,日米共同大型高速炉臨界実験(JUPITER)のフェーズI(電気出力6080万kWe級の2領域均質炉心模擬体系シリーズ)について,これまでの炉物理研究の成果として確立された最新解析手法を用いて再解析を行い,これを評価した。今回用いた解析手法及び主要解析結果を示す。(1)解析手法 (1)核断面積:JENDL-2ベースの70群高速炉用定数セットJFS-3-J2(89年版)(2)セル計算 :プレートストレッチモデル,Toneの方法によるプレート非均質効果カレント重み輸送断面積(3)体系基準計算 :3次元XYZ体系18群拡散計算,Benoistの異方性拡散係数(4)体系補正計算 :3次元輸送,メッシュ,非対象セル,AMM効果など(2)解析結果(1)臨界性のC/E(計算/実験)値は,各炉心間(ZPPR-9,10A10D/2)でよく安定しており,0.9937+ー0.0006である。炉心体積やCRP有無などに対するC/E値依存性は見られない。(2)制御棒価値のC/E値は,各炉心の中央部から径方向の外側に行くほど大きくなる径方向依存性が見られる(511%)。また,反応率分布のC/E値にも同様の径方向依存性(25%)が見られ,制御棒価値の傾向とほぼ対応している。(3)C28/F49,F25/F49の反応率比C/E値は各炉心間で安定しており,内側炉心部では,それぞれ1.06,1.03である。(4)Naボイド反応度のC/E値は,炉心中央部平均で約+25%の過大評価である。

A series of critical experiments for conventional two-zone homogeneous cores of 6 to 8 MWe-class LMFBR, JUPITER phase-I, were analyzed and evaluated using the latest analytical method, which had been established from the preceding numerous studies on fast reactor physics. The present work is a part of efforts to develop a standard data base for LMFBR core nuclear design at PNC. The analytical method and results are summarized as follows: (1)Analytical method (a)Nuclear data : 70-group fast reactor constant set JFS-3-J2(1989 edition) based on the Japanese Evaluated Nudear Data Library, version 2 (JENDL-2). (b)Cell calculation : plate stretch model, cell heterogeneity treatment by Tone's method and transport cross-sections weighted with neutron current. (c)Base core calculation : 18-group, three-dimensiona1 XYZ diffusion theory and Benoist's anisotropic diffusion coefficients. (d)Correction calculation : three-dimensional transport effect, mesh size effect, cell asymmetric effect and all master model effect etc. (2)Analytical results (a)The C.E (calculation/experiment) values of criticality agree quite well among seven cores (ZPPR-910D/2) and do not depend on the core volume or the number of control rod positions (CRP). (b)The C/E values of control rod worths increase gradually from the core center to the core edge positions in each core (511%). Those of reaction rate distributions also indicate similar spatial variations (25%), which is considered to be consistent with the C/E tendency of control rod worths. (c)The reaction rate ratios of C28/F49 and F25/49 give quite stable C/E values of 1.06 and 1.03, respectively. (d)The C/E values of sodium void reactivities are overestimated by +25% at core center region. The C/E dependence on void region size, which was pointed out in the past analyses, is found in the ZPPR-9 core, but not in the ZPPR-10 series. (e)The C/E dependence of 4% on the radial positions were found in sample ...