Code analysis on transient behavior of LWR MOX fuel during the test-irradiation in Halden reactor

軽水炉MOX燃料のHalden炉試験照射における過渡時ふるまいの計算コード解析

鈴木 元衛; 永瀬 文久 

Suzuki, Motoe; Nagase, Fumihisa

PWRでベース照射され、ハルデン炉で試験照射されたMOX燃料のふるまいを、解析コードの最新バージョンFEMAXI-7で解析した。計算条件には、ベース照射から試験照射まで一貫して線出力,出力密度プロファイル,冷却条件などを与え、燃料の温度,FPガス放出,被覆管変形等を求めた。試験照射における計算値を実測値と比較した結果、燃料温度,FPガス放出や内圧等の熱的解析結果では妥当な一致が得られたが、被覆管の変形は多くの要因の相互作用の結果、満足すべき計算結果を得るためにはモデルやそのパラメータの最適な組合せを分析・考慮する必要があることが示唆された。

The behavior of MOX fuels which were base-irradiated in PWR and test-irradiated in the Halden reactor was analyzed by the latest version of fuel performance code FEMAXI-7. For the calculation conditions, linear heat rate history, power density profile, and coolant condition etc. were given consistently from the base- to test-irradiation to predict the fuel temperature, fission gas release rate, and cladding deformation, etc. Comparison of calculated values with the measured data during the test-irradiation shows a reasonable agreement in thermal analysis results such as fuel temperatures and fission gas release rates, while the cladding deformation, which is involved with various interactions, suggests that it is still necessary to analyze and consider an optimum combination of models and their parameters to obtain a satisfactory prediction.