核电站核二、三级换热器传热管多为进口304L不锈钢,新建核电站已陆续采用国内制造的304L传热管.试验模拟了传热管实际应用环境,对国产304L的点蚀行为及核岛废液环境下应力腐蚀行为进行研究.结果表明,发生点蚀的临界FeCl3溶液质量分数为0.1%和0.5%之间;随着氯离子浓度的增加,304L自腐蚀电位降低.模拟核电站核岛废液环境(H3BO3＋NaOH＋Cl-),制作反U型弯曲试样,使用高温高压釜进行500 h模拟试验,304L未发现应力腐蚀裂纹.

Imported 304L was used in nuclear safe grade 2 and 3 heat exchanger tubes in nuclear power plants and domestic materials are used in new built plants.In simulated actual running environment,pitting corrosion and stress corrosion cracking (SCC) of domestic 304L in nuclear island waste residue environment were studied and evaluated.Results showed that critical FeCl3 concentration for pitting corrosion was between 0.1% and 0.5%.Polarization curves showed that the corrosion potential increased with reducing Cl- concentration.Five hundred hours experiment was performed in autoclave with simulated nuclear island waste residue environment of H3BO3＋NaOH＋Cl- by using reverse U-bend samples and the results showed that SCC did not appear.