Hydrogen water chemistry operating experience

In late 1984, the Dresden-2 Nuclear Power Station of the Commonwealth Edison Company (USA) completed an entire 18-month fuel cycle while operating under a Hydrogen Water Chemistry (HWC) specification. Under joint General Electric/Electric Power Research Institute sponsorship, the water chemistry, materials performance and fuel performance were monitored closely during both that fuel cycle and the current fuel cycle. The findings to date are discussed in detail, including (1) results of in-reactor testing which show that intergranular stress corrosion cracking (IGSCC) initiation and growth in sensitized stainless steels is precluded by the establishment of HWC conditions, (2) the long term trends in water chemistry, including topics such as oxygen content, conductivity, corrosion products and electrochemical potential, and (3) a review of the available fuel component examination results. The experience at Dresden-2 is also compared with the results of other US plants of similar design. These results are then contrasted with other reported experience which indicates that the detailed specification for IGSCC immunity via HWC can vary considerably with system design. (author)