Zirconium Alloys High-Frequency Treatment
Investigation of Reactor Irradiation Effect on Radiation Stability and Mechanical Properties of Articles from Zirconium Alloys after High-Speed High-Frequency Treatment
Tech Area / Field
- FIR-MAT/Materials and Materials Conversion/Fission Reactors
3 Approved without Funding
NIIAR (Atomic Reactors), Russia, Ulianovsk reg., Dimitrovgrad
- EDF / Direction des Etudes et Recherches, France, Moret-sur-Loing\nABB Atom AB, Sweden, Vàsteràs
Project summaryThe project is to be implemented in conjunction with STCU project # 1577-J.
STCU project #1577 name is “Investigation of reactor irradiation effect on radiation stability and mechanical properties of articles from zirconium alloys after high-speed high-frequency treatment “
The Russian Project ( ISTC #1756) implementation connected with Ukrainian project (#1577J) implementation and factually just funding of both projects can come to the important results.
Title: Investigation of reactor irradiation effect on radiation stability and mechanical properties of articles from zirconium alloys after high-speed high-frequency treatment.
Field of application: Manufacture of items for the water-cooled atomic reactor active zones, the increase of their service life and reliability.
Aim: Testing of items from zirconium alloys improved by using the high-frequency treatment, developed by present authors, and investigation of the radiation effect on the structure and mechanical properties of the alloys. Experimental and theoretical substantiation of the new approach to achieve high radiation stability of zirconium alloys according to the received data.
Main goal: Experimental investigation of the relationships between the changes of macroscopic characteristics (strain of irradiation growth, strain of creep, short-term mechanical properties), resulting in effect high-dose reactor radiation (up to fluence 4.1026 m-2, E>0,1 MeV), and the features of microstructure (radiation damages, twins, grain boundaries, dislocations, precipitates of secondary phases, lattice parameters, etc.) of the Zr-Nb alloys after high-speed high-frequency treatment and radiation in comparison with traditional scheme (annealing ) of treatment.
Proposed technology and its advantage: The treatment includes a special preliminary deformation of the alloy, rapid high-frequency heating up to beta-phase temperature region 950...970oC and a short exposure at this temperature with a subsequent quenching at a rate of 1000oC per second, and a prolonged aging in the high temperature region of alpha-phase stability. As a result, the grain orientation distribution of the alloy becomes quasi-isotropic (i. e. the initial texture is destroyed) and contains a high density of homogeneously distributed stable beta-Nb precipitates. Such treatment will cause the notable decrease of strain of irradiation dimensional changes of zirconium alloys and conserve or increase their short-term mechanical properties.
Benefit effect: The problem of zirconium alloys active zone items (channels, pins) service life and reliability due to limitation of their permissible irradiation dimensional changes strain will be solved in going and designing nuclear reactors. It will promote the increase of energy production, nuclear reactor safety, environmental protection in accordance with national priorities of Ukraine and Russia and ISTC aims.
In this case:
the Ukrainian party· realizes heat treatment developed by present authors of large scale channel and cladding tubes from zirconium alloys Zr-2,5%Nb and Zr-1%Nb; produces samples from these tubes and transmits to their Russian party;
· carries out investigations of physical and mechanical properties of unirradiated samples, subjected to high-speed high-frequency treatment;
· is engaged within the framework of the project in development of theoretical bases of interaction of radiation point defects with structural features of alloys;
· develops computer codes of technological process of treatment and radiation tests of zirconium alloys;
the Ukrainian party together with the Russian party participates in:· the analysis of methodical possibilities of realization of radiation experiments including an estimation of influences of irradiation conditions on parameters of interaction between structural singularities and point defects in Zr-Nb alloys,
· the analysis of existing data on influence of radiation on structure and properties of alloys of this system,
· discusses the results, received by both parties, with allowance for theoretical estimations of parameters of interaction between structural singularities and point defects,
· develops the recommendations for use of offered technology of heat treatment of tubes to test reactor (SМ-2) and power atomic reactors (CANDU, BWR and RBMK).
The Russian party
· studies possibilities of definition of conditions of a radiation and feature of realization of experiments on test of samples from zirconium alloys for investigation of their radiation stability, prepares the equipment for such investigations;
· produces dismountable irradiation system for tests in a reactor BOR - 60 of samples, delivered by the Ukrainian party;
· analyzes with them existing data on influence of irradiation on structure and properties of zirconium - niobium alloys;
· carries out experiments on investigation of influence of a reactor irradiation by fluences (E > 0,1 МэВ) up to 4.1026 m-2 on dimensional performances (irradiation growth, a creep) and mechanical properties of samples (impact toughness, strength and plasticity upon a tension);
· carries out electron-microscopical and X-ray diffraction investigations irradiated up to different levels of radiation damage of samples,
· determinates the correlation between structure evolution and macroscopic properties of the irradiated zirconium alloys of previously subjected high-speed high-frequency treatment;
· together with the Ukrainian party discusses the possible mechanisms and regularities of changes of properties of these materials due to irradiation and develops the recommendations for use of technology of high-speed high-frequency heat treatment of tubes in test reactor (SМ-2) and power atomic reactors (CANDU, BWR and RBMK).
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