報告書番号

T91049

タイトル（和文）

高温水におけるインコネル６００合金のき裂進展性評価（その２）－き裂進展挙動に及ぼす水質・応力因子の評価－

タイトル（英文）

EVALUATION OF CRACK PROPAGATION OF ALLOY 600TUBE IN HIGH-TEMPERATURE WATER(PART 2) -EVALUATION OF EFFECT OF WATER QUALITY AND STRESS ON CRACK PROPAGATION-

概要 （図表や脚注は「報告書全文」に掲載しております）

ＰＷＲ蒸気発生器伝熱管に生じた粒界腐食／応力腐食割れ（ＩＧＡ／ＳＣＣ）き裂の進展挙動を明確化すること，および新たな水中添加剤によるき裂進展抑制効果を明らかにし，実験室段階での対策の提案を行うことを目的とし，ＩＧＡ／ＳＣＣき裂進展抑制評価試験を実施し以下の結果を得た。（１）高アルカリ環境中でのＩＧＡ／ＳＣＣ試験結果より，実機伝熱管に作用する応力値の範囲内ではき裂進展速度が急激に速くなる領域は存在しない。（２）実機温度，圧力および熱流束を模擬した沸騰伝熱条件下でＩＧＡ／ＳＣＣ試験を実施した結果，き裂進展速度は，１０＊＊－３～１０＊＊－２ｍｕｍ／ｈｒと十分に遅かった。（３）アルカリ環境中への微量な硝酸ナトリウムおよび二酸化窒素ガスの添加は，粒界腐食割れを著しく抑制することを明らかにした。

概要 （英文）

INTERGRANULAR ATTACK AND STRESS CORROSION CRACKING (IGA/SCC) HAVE RESULTED IN EXTENDED OUTAGES AT MANY PWR PLANTS. IT IS IMPORTANT TO CLARIFY THE IGA/SCC PROPAGATION BEHAVIOR AND TO ESTABLISH COUNTERMEASURES TO IGA/SCC. THE PREVIOUS PAPER REPORTED THE ANALYSIS OF THE STRESS INTENSITY FACTOR AT THE CRACK TIP IN ALLOY 600 STEAM GENERATOR (SG) TUBES. THIS REPORT DESCRIBES THE EFFECT OF THE STRESS INTENSITY FACTOR AND INHIBITERS ON THE IGA/SCC PROPAGATION BEHAVIOR IN ALLOY 600 SG TUBE. THE MAIN TEST RESULTS ARE AS FOLLOWS:(1)IGA/SCC TEST RESULTS USING A DOUBLE CANTILEVER BEAM (DCB) SPECIMEN SHOWED THAT IGA/SCC CRACKS DO NOT PROPAGATE RAPIDLY AT THE STRESS INTENSITY FACTOR THAT THE IGA/SCC CRACK TIP OF SG TUBE EXPERIENCES UNDER PWR SECONDARY CONDITIONS. (2)A MODEL BOILER,WICH WAS MANUFACTURED TO SIMULATE TUBE SUPPORT PLATES,WAS TESTED TO EVALUATE THE IGA/SCC PROPAGATION RATE. METALLOGRAPHIC EXAMINATION OF TUBES TO EVALUATE THE IGA/SCC PROGATION RATE. METALLOGRAPHIC EXAMINATION OF TUBES FROM THE MODEL BOILER (FAULTED WITH SODIUMHYDROXIDE) REVEALED THAT THE IGA/SCC PROPAGATION RATE RANGED FROM 10**-3 10**-2 MU M/H. (3)IGA/SCC TESTS USING DCB AND THE MODEL BOILER REVEALED THAT ADDITION OF SODIUM NITRATE AND NITROGEN DIOXIDE SUPPRESSED IGA/SCC CRACK PROPAGATION.

報告者

キーワード