報告書番号

385034

タイトル（和文）

冷却水放水口近傍域での高温領域拡散予測手法の開発

タイトル（英文）

DEVELOPMENT OF PREDICTIVE METHOD FOR THERMALDIFFUSION IN THE SEA NEAR THE COOLIING WATER OUTLET

概要 （図表や脚注は「報告書全文」に掲載しております）

現在，表層放流方式に対する放水口より遠方領域の予測はほぼ実用段階に達していると考えられる。この予測手法は流速，水温について指数的な鉛直分布を表現した２次元モデルで冷却水放水による流れ海域の流れと乱れ，大気・水面間の熱収支等を考慮した式系から成り立ち低温上昇域（１～３℃）の予測に意図をおいたモデルである。近年，発電所の大容量化による温排水放流量の増大に伴い従来にくらべ放水口近傍での高温度水温上昇域が拡大するため高温域を対象とした領域について，より精度の高い予測が必要になると考えられる。本報告書は放水口近傍域における表層密度噴流の混合現象を精度よく再現するために，３次元数理モデルによる解析を展開し，解析結果と水理実験結結果と比較検討し放水口近傍での高温領域拡散予測手法の実用化をはかったものである。本文で展開した３次元数理モデルは従来の２次元数理モデル（遠方領域モデル）では表現できなかった放水口

概要 （英文）

IT SEEMS THAT THE PREDICTION OF THERMAL DIFFUSION IN THE AREA FAR AWAY FROM THE OUTLET BY A SURFACE DISCHARGE METHOD HAS NOW REACHED AN ALMOST PRACTICAL STAGE. THIS PREDICTION TECHNIQUE USES A TWO-DIMENSIONAL MODEL WHICH EXPRESSES EXPONENTIALLY THE VERTICALDISTRIBUTION OF FLOW VELOCITIES AND WATER TEMPERATURES AND CONSISTS OFEQUATIONS CONSIDERING FLOW OWING TO THE DISCHARGE OF COOLING WATER,CURRENT AND TURBULENCE IN THE SEA AREA,HEAT BALANCE BETWEEN THE ATMOSPHEREAND THE WATER SURFACE,ETC. THE MODEL IS INTENDED TO PREDICT THE DIFFUSION IN THE LOW-TEMPERATURE RISE AREA(1 3DEGREE). WITH AN INCREASE IN THE DISCHARGE RATE OF WARM WATER DUE TO AN INCREASE IN THE CAPACITY OF POWER PLANTS IN RECENT YEARS,THE HIGH WATER-TEMPERATURE RISE REGION NEAR THE OUTLET IS EXPANDDING MORE THAN EVER,MAKING IT NECESSARY TO CARRY OUT MORE HIGHLY ACCURATE DIFFUSION PREDICTION WITH A HIGH TEMPERATURE-RISE REGION AS A SUBJECT AREA. THE OBJECT OF THIS REPORT IS TO EVOLVE AN ANALYSIS BY MEANS OF A THREE-DIMENSIONAL MATHEMATICAL MODEL SO AS TO REPRODUCE WITH HIGH ACCURACY THE MIXING PHENOMENON OF A SURFACE DENSIMETRICJET IN THE AREA NEAR THE OUTLET AND TO PROMOTE THE PRACTICAL USE OF A TECHNIQUE FOR PREDICTING THE THERMAL DIFFUSION IN THE HIGH-TEMPERATURE AREA NEAR THE OUTLET THROUGH A COMPARATIVE STUDY BETWEEN THE RESULT OF ANALYSIS AND THE RESULT OF A HYDRAULIC TEST. THE THREE-DIMENSIONAL MATHEMATICAL MODEL DEVELOPED IN THIS REPORT WAS ABLE TO EXPRESS ADEQUATELY THE PHENOMENA OF ENTRAINING SEA WATER INTO THE DISCHARGED WATER IN THE AREA NEAR THE OUTLET WICH THE CONVENTIONAL TWO-DIMENSIONAL MATHEMATICALMODEL (FAR FIELD MODEL) COULD NOT EXPRESS. THIS MODEL PERMITS HIGHLY ACCURATE PREDICTION OF A HIGH-TEMPERATURE RISE ZONE (3 5DEGREE) CAUSED BY THE DISCHARGE OF WARM WATER.

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