報告書番号

V10009

タイトル（和文）

原子力施設・排ガス拡散予測のための数値モデルの実用化検討-数値モデルの性能確認-

タイトル（英文）

Practical Capability of an Atmospheric Diffusion Numerical Model for Safety Analysis of Nuclear Facility -Sensitivity Analysis of a Numerical Model-

概要 （図表や脚注は「報告書全文」に掲載しております）

安全解析のための原子力施設からの排ガス拡散予測を対象に、放出源の有効高さを評価する数値モデルを開発した。本報告では、始めに数値モデルを単純建屋に適用し、既存の風洞実験結果で得られた空間濃度値と比較し、技術基準で求められる可能性がある性能を満足することを示した。次いで、数値モデルを複雑地形地点に適用し、複雑地形特有な煙軸曲がりを風洞実験と同様に数値モデルにより予測できることを示した。さらに、排ガスの水平方向の拡がりのパラメータを実際の大気で生じる風向変動を考慮して増加させて設定し、実発電所での有効高さの変化が小さいことを示した。

概要 （英文）

A numerical simulation model has been developed to predict atmospheric flow and stack gas diffusion, considering the buildings and complex terrain located near and relatively far from a stack, respectively. The developed numerical model has been applied to estimate the effective stack height used for the safety analysis of nuclear facility. The flow around a rectangular building and tracer gas emitted behind a building were simulated using a numerical model at first in this report. The calculated results were compared with those of wind tunnel experiment and it was apparent that requested performance, viz., factor two ration of calculated concentration around a building, of a numerical model was obtained. Then, a numerical model was applied to calculate the flow and stack gas diffusion for actual nuclear facility under the extremely complex terrain. The meandering features of surface concentration of tracer gas, caused by the extremely complex terrain, obtained in wind tunnel experiment were also calculated by a numerical model. Furthermore, the variations of effective stack height with the increment of the horizontal plume spread under flat-plate condition were calculated at actual nuclear facilities under the building and terrain condition, and compared with those under small horizontal plume spread under flat-plate condition. It was apparent that almost the same values of effective stack heights were calculated under both horizontal plume spread conditions.

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