Zirconium for Nuclear Primary Steam Systems

Abstract

Zirconium and zirconium alloys provide the best combination of metallurgical and mechanical properties for light and heavy water nuclear reactor fuel cladding and for the primary steam generation equipment. However, before materials may be used in such applications, long-term mechanical properties within the reactor operating temperature range must be established. Also, fabrication methods for such systems must be developed and evaluated. In order that zirconium would become a qualified ASME Boiler Code material, a long-term test program was initiated; the qualifying data is presented in graphical form. The statistical data on short-term physical tests is amplified by the long-term creep rate and rupture-life versus temperature data. Primary steam generation equipment fabrication data and criteria are presented with examples. Examples of the use of zirconium and zirconium alloys in nuclear and non-nuclear structures is reported; the stages necessary to fabricate components for the large nuclear steam generation equipment used in commercial power production is discussed. Additional data required by international specifications is also presented, including charpy impact and fatigue data, as well as the normal mechanical property tests.