Cel
The objective of this proposal is to determine the limiting physical parameters for the justified use of specimen reconstitution techniques for Charpy-V impact and precracked Charpy fracture toughness testing in nuclear plant life management.
The ageing of nuclear pressure vessels (PV) is monitored with surveillance capsules, which contain Charpy V-notched (Cv) and tensile specimens manufactured of representative base and weld metals, and which are located near the inner vessel wall. Due to the accelerated irradiation position, i.e. the existence of a lead factor between the neutron dose rate at the specimen location and the vessel wall, the specimens predict the embrittlement properties of the wall at later time.
For most reactors the surveillance programme provides material data for the designed reactor life span only. In some cases the original surveillance programme needs to be supplemented with information to cover the whole period of reactor operation. Direct fracture toughness data, dynamic versus static test data or, data on annealed or reirradiated material conditions are in some cases strongly recommended. As the content of most surveillance capsules has been tested destructively, only broken specimens and a small number of vintage material remain in storage.
In situations where the material data base is small or inadequate, specimen reconstruction or 'reconstitution' techniques - usually the welding of end blocks to a central insert piece, made of the remaining material of interest - allow reuse of this material to study the ageing behaviour of the reactor pressure vessel. The condition sine-qua-non is that the fracture parameters of interest of the insert are not influenced by the welding procedure. The present RESQUE project is scientifically promoted by the European Network AMES, "Ageing Materials Evaluation and Studies". The AMES Network deals with the material aspects in the field of irradiation embrittlement and mitigation methods.
The RESQUE project is designed to qualify and verify the reconstitution techniques. The project will identify the limits of applicability of technical reconstitution parameters, that have the potential to affect the experimental values measured with reconstituted specimens. Two types of specimens will be considered: Cv-impact and fracture toughness. The initial emphasis will be put on un-irradiated material in order to save on expensive hot-cell work. Afterwards the optimum reconstitution procedure will be verified on irradiated PV steels, like IAEA reference steels and the steels from the REFEREE programme.
The overall analysis of the data gathered during the research project will lead to a common European Practice for the Reconstitution of Irradiated Cv and Fracture Toughness Specimens.
Temat(-y)
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CSC - Cost-sharing contractsKoordynator
1160 BRUXELLES
Belgia