[en] Failure prevention and analysis research program is on going for the steam generators, condensers and turbines of PWR's and PHWR CANDU in order to obtain analysis and evaluation technology for material failures which take place and might occur in the Korean nuclear power reactors in future. As a part of this program, failure experiences have been surveyed for steam generators, condensers and turbines of PWR's in foreign countries, and operating experiences have been surveyed for nuclear power unit 1 in Korea with PSI and ISI eddy current test data, water chemistry data and failed specimens. The Korean nuclear power unit 1 has minor denting indications and boric acid soaking has been performed in order to control the denting. The effects of this boric acid soaking on the material degradation of the PWR secondary system are being studied. Stress corrosion cracking research work is also under way for steam generator U-tubes. (Author)