報告書番号

T94019

タイトル（和文）

沸騰伝熱隙間部の不純物濃縮挙動（その２）－電導度測定による沸騰伝熱隙間部の不純物濃縮度の推定－

タイトル（英文）

IMPURITY CONCENTRATION ON BOILING HEAT TRANSFER SURFACE IN TUBE-TUBE SUPPORT PLATE CREVICE (PART 2) -ESTIMATION OF IMPURITY CONCENTRATION FACTOR ON BOILING HEAT TRANSFER SURFACE IN TUBE-TUBE SUPPORT PLATE CREVICE USING CONDUCTIVITY MEASUREMENT-

概要 （図表や脚注は「報告書全文」に掲載しております）

ＰＷＲプラントにおいて給水中に微量に溶解している不純物が蒸気発生器の伝熱管と管支持板との■間部で著しく沸騰濃縮し、伝熱管に局部腐食が発生している。本研究の目的は、その場測定手法を用いて不純物の濃縮をその場で測定することである。本報告では、実機と同一形状のインコネル６００合金伝熱管と４０５ステンレス鋼支持板との■間部水の電導度測定から濃縮度を算出し、濃縮に及ぼす熱流束および水質の影響に関し、同手法の適用可能性を実機の熱流束を模擬した高温高圧の脱気水酸化ナトリウム水溶液中で検討し、以下の結果を得た。（１）高温高圧の水酸化ナトリウムの電導度は、濃度および温度の上昇とともに増加した。（２）■間部以外の電導度に比べ、■間部の方が高いことから、■間部で水酸化ナトリウムの濃縮が起きているものと考えられ、本手法は沸騰濃縮のその場測定に適用可能であることを明らかにした。また、ドライ＆ウェットが発生する

概要 （英文）

LOAD CORROSION HAS BEEN EXPERIENCED ON THE SECONDARY SIDE OF STEAM GENERATOR TUBES IN TUBE-TUBE SUPPORT PLATE CREVICES OF PWR S, BECAUSE SLIGHT IMPURITIES DISSOLVED IN THE FEED WATER ARECONCENTRATED IN THE CREVICES. VARIOUS CHEMICAL ANALYSES HAVE BEEN USEDTO EVALUATE WATER QUALITY IN THE CREVICES, BUT IT HAS BEEN VERY DIFFICULT TO ANALYZE EXACTLY BY INDIRECT ANALYSIS. THIS STUDY CALCULATED THE IMPURITY CONCENTRATION FACTORS FROM THE RESULTS OF HIGH-TEMPERATURES ODIUM HYDROXIDE AQUEOUS CONDUCTIVITY MEASUREMENTS IN THE CREVICE. THE EFFECTS OF HEAT FLUX AND SOLUTION TEMPERATURE ON THE IMPURITY CONCENTRATIONS WERE EXAMINED. THE CONDUCTIVITY IN THE CREVICE WAS MEASURED IN DEAERATED SODIUM HYDROXIDE AQUEOUS SOLUTION IN THE RANGE 260-280 DEGREE. THEMAIN TEST RESULTS ARE AS FOLLOWS: (1)CONDUCTIVITY OF HIGH-TEMPERATURE WATER INCREASED WITH INCREASING CONCENTRATION AND TEMPERATURE IN DEAERATED SODIUM HYDROXIDE SOLUTION. (2)THE TEST RESULTS SHOWED THAT THE CONDUCTIVITY IN THE TUBE-TUBE SUPPORT PLATE CREVICE SOLUTION WAS HIGHER THAN THAT OF BULK WATER AND SODIUM HYDROXIDE WAS CONCENTRATED IN THE CREVICE. THIS MEHTOD WAS APPLICABLE TO EVALUATION OF IMPURITY CONCENTRATION BEHAVIOR IN THE CREVICE. FROM THE CALCULATED CONCENTRATION FACTORY THE FACTOR WAS ABOUT 2000 IN THE RANGE OF THE HEAL FLUX FOR THE REGION OF DRY AND WET CONDITIONS. THE IMPURITY CONCENTRATION IN THE CAUSTIC-HYDROXIDE SOLUTION WAS LOWER THAN THAT OF FIELD DATA.

報告者

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