Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: Lifetime extension of the Phenix nuclear power plant

Martin, L.; Pepe, D. (CEA-Phenix, Bagnols-sur-Ceze (France)); Dupraz, R. (Framatome-ANP, Lyon (France))

Abstract

The French fast reactor prototype: Phenix, located at Marcoule in the Gard department, was put into commercial operation in 1974. The total time of power operation of the plant is approximately 100,000 hours. The initial objective of Fast Breeder Reactor demonstration has been achieved. Since the mid-nineties, the role of the reactor as an irradiation facility has been emphasized, particularly in support of the CEA's transmutation R and D programme in the context of the 30th December 1991 French law on long-lived radioactive waste management. This new objective has required the extension of the planned reactor lifetime. A renovation programme was defined based on: - Plant safety improvements based on today's standards. - Evaluations and inspections of components in order to assess their condition and to identify possible damaging mechanisms. - The estimation of the ability of components to continue operation taking into account the experimental feedback. The safety upgrading of the plant consisted essentially of the following: - The addition of a safety control rod to the reactor. The partitioning of the secondary sodium circuits in the Steam Generator building to improve protection against sodium fires. - The installation of an anti- whip system on the high-pressure steam pipes. - The construction of two redundant seismic resistant emergency water-cooling circuits. - The seismic reinforcement of the plant buildings. An extensive evaluation campaign was carried out on all the equipment that is essential to safety. Damaging phenomena were systematically investigated. Following the evaluation, the equipment was either repaired or replaced, or it was demonstrated that equipment condition allowed lifetime to be extended. Among the major works performed was the replacement of the 321 stainless steel hot leg of the secondary loops and the repair of the superheater and reheater SG modules. This latter operation is currently underway. The repair process consists in dismounting the modules, washing the internal residual secondary sodium, replacing potentially defective parts and remounting. Special analysis was conducted regarding the reactor block structures. The past and future damage rates were evaluated, involving investigation of manufacturing data, determination of the behaviour of some particular mechanical assemblies such as welded joints, estimation of the loadings from operating conditions associated with thermal calculations. In addition to these studies, and as a second defence line, the main reactor structures were inspected using various techniques. Because of the difficult access to the structures, original inspection procedures had to be developed and special equipment designed and manufactured. The inspections included: - Ultrasonic examination of the reactor vessel upper hangers. - Ultrasonic examination of the core support conical shell. - Televisual examination of the core cover plug. Most of the renovation programme of the plant has been completed. The major remaining task is the repair of the SG modules. The power rising of the reactor is expected before the end of 2002. Six 120 EFPD operating cycles are scheduled to carry out the irradiation programme, representing about five-and-a-half years of operation. Considerable experience has been gained from the lifetime extension project in many fields, including the methodology that was developed, materials and components behaviour, inspection techniques. (author)

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key words: eccs; engineered safety systems; fire prevention; in-service inspection; phenix reactor; reactor components; reactor control systems; reactor maintenance; reactor safety; reactor vessels; repair; safety standards; sodium; steam generators; ultrasonic testing; breeder reactors; enriched uranium reactors; epithermal reactors; fast reactors; fbr type reactors; liquid metal cooled reactors; lmfbr type reactors; plutonium reactors; power reactors; sodium cooled reactors;
Reference:
Proceedings of a Technical Meeting held in Cadarache, France 11-15 March 2002
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--1405, pp:83-91