Improvement of Reliability in Nuclear Power Plants by Water Chemistry Technology
As of 1999, 28 BWR units and 23 PWR units are operated, and the generation of electric power by light water reactors accounts for 35% of the total electric power generation in Japan. However, light water reactors have experienced many corrosion problems since the first commercial operation started in 1970.
To cope with these corrosion problems, variour countermeasurements have been developed and employed. In the case of BWRs, nuclear grade 316LC stainless and new weld methods were developed in order to prevent pipe cracking in recirculation system. Hydrogen injection are also employed to prevent the SCC of in-reactor materials. On the other hand, in the case of PWRs, thermally treated alloy 690 (690TT) was developed and employed to prevent the IGA/SCC for Steam Generator tubing. Zinc injection has been investigated to control the radiation build-up in both BWRs and PWRs.
In this report, the status of advancement of reliability in nuclear power plant by the improvement of materials performance, water chemistry and design in Nuclear Power Plant is reviewed, and the subjects which will be dealed with in the future are discussed.