Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: A lifetime extension project for the PHENIX reactor: additional knowledge regarding the in-service behaviour of its materials and structures

Martin, P. (CEA/DRN/DER/SERA, St. Paul-lez-Durances (France)); Jerrige, L. (DCP/MSAQ, Central PHENIX, Marcoule (France)); Forgeron, T. (CEA/DEM/SRMA, Saclay (France)); Devos, J. (CEA/DMT/SEMT, Saclay (France))

Abstract

The PHENIX Life Extension Project groups together all the actions required to pursue operation of the reactor, particularly with a view to performing irradiation experiments in the framework of the back-end of the fuel cycle programs. As such, it comprises a series of investigations whose objective is to assess the state of the reactor after about one hundred thousand hours of operation. The following points have been particularly investigated : The materials behavior (austenitic, austeno-ferritic, and ferritic steels - base metal, welds, heat affected zones) in terms of thermal aging and its effect on mechanical properties, embrittlement, sensitiveness to corrosion (in normal and incidental environment), and radiation effect on the potentially exposed structures. Furthermore, specific programs have been devoted to the assessment of thermo-mechanical response of some particular components. This concerns some types of welds with regard to fatigue or creep fatigue, some parts of large shells with regard to ratchetting and buckling, and main secondary piping. An extensive program was dedicated to the recovery of the thermo-mechanical damage undergone by the structures and its extrapolation to the future. This has led to consider in details thermo-hydraulical effects such as fluctuations in streams and bedding zones. Some intergranular cracking of welded joints had to be closely examined; this was achieved by a research work that has produced important advancements in that field. With the aim of evaluating potential defects, real progresses have been made in the knowledge of large defect’s behavior in thin shells. The feedback of the examination and studies was also derived in terms of relevance of manufacturing, exploitation and monitoring conditions. It is believed that this experience will be useful for future design rules.

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key words: aging; corrosion fatigue; embrittlement; mechanical properties; phenix reactor; reactor components; reactor operation; steels; thermal degradation

Reference:: Technical committee meeting on unusual occurrences during LMFR operation. Vienna (Austria) 9-13 Nov 1998; International Atomic Energy Agency, Vienna (Austria); IAEA-TECDOC--1180, pp:238-248