State of the RBMK CPS Channels from Post-Reactor Studies

Abstract

Serviceability validation of the efficiency of CPS channels operating beyond the design basis service life is one of the tasks in reactor service life extension problems. Periodic post-reactor examinations of sections of a channel in shielded enclosures are conducted as part of routine monitoring. Currently, CPS channels with operating times 4–37 calendar years have been investigated. It was found that according to the shape change, corrosion state, hydrogen content, mechanical properties, and characteristics of the fracture toughness of zirconium tubes, electron-beam weld connections, and steel-zirconium adapters the CPS channels remain serviceable. An increase in hydrogen content was found in the material of the tubes and adapter nipples of the CPS channels after operation for more than 26 years. The high hydrogen content is accompanied by the appearance of hydride accumulations on the inner surfaces of local regions. The nature and causes of this phenomenon have not been found.