Radiation Resistant Zirconium Alloys
Development of Scientific Fundamentals for Creation of Irradiation Resistant Structural Zr Alloys for Nuclear Reactor Cores
Tech Area / Field
- MAT-ALL/High Performance Metals and Alloys/Materials
3 Approved without Funding
All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
- Ural Branch of RAS / Institute of Metal Physics, Russia, Sverdlovsk reg., Ekaterinburg\nNIIAR (Atomic Reactors), Russia, Ulianovsk reg., Dimitrovgrad\nVNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Korea Atomic Energy Research Institute, Korea, Yusung Taejon\nAdvanced Nuclear Technology, Uppsala Science Park, Sweden, Uppsala\nCEA / DTA / CEN Grenoble, France, Grenoble
Project summaryThe suggested Project is aimed at developing approaches to establish scientific criteria that would provide the high reliability of Zr-alloy component operation in light water reactor cores under neutron irradiation to fluence of 5×1026 n/m2 (E і 0.1 МeV) and higher.
The Project implementation assumes the following:
– acquire experimental data base on changes in physico-mechanical properties of Zr alloys in Zr-Nb-Fe-Sn and Zr-Nb systems depending on irradiation conditions;
– assess the influence effected by neutron field factors (neutron flux and fluence, temperature of irradiation and hydrogen uptake) on microstructure and properties of alloys and on the basis of which suggest scientifically founded approaches to optimization of composition and structure of Zr-alloys for use as reactor core components.
Using updated experimental analytic methods, the Project assumes implementation of investigations in the following directions:
1. Experimental and commercial reactor irradiation of alloys and studies of their physico-mechanical properties (irradiation induced growth, creep, short-term tensile properties) as interrelated to their microstructure evolution under different irradiation conditions.
2. Studies into the cause and mechanism of accelerated irradiation growth vs structure and phase conditions of alloys having different compositions as well as investigation of thermally and irradiation induced transformations of alloys. Examinations of changes in phase crystal structures, alloying element redistribution (specifically Nb and Fe) between second phase precipitates and solid solution using methods of analytic electron microscopy, neutron radiography and Mössbauer effect. Mössbauer examinations of Zr alloys containing different quantities of Fe57 species allows tracing alloying elements diffusion to minor distances within 1 or 2 coordination spheres.
3. Determination of hydrogen location in original and irradiated specimens and its influence on formation of solid solutions and hydrides in Zr-alloys is assumed to be carried on by microradioautography using model samples saturated with tritium to various concentrations. Methods of nuclear reactions, positron annihilation and electrical resistance will be employed to study the feasibility of suppressing Zr hydride formation processes that embrittle alloys during operation at the expense of:
– forming phase states that inhibit formation of stable hydrogen segregations;
– creating diffusion-barrier layers that inhibit hydrogen penetration into alloys;
– increasing hydrogen solubility in potentially hazardous areas of construction elements.
4. Direct influence of point defects on tensile property degradation of different Zr alloys will be clarified under low temperature (80 K) neutron irradiation that allows accumulation of essentially immobile vacancies and interstitials at rather low neutron fluences.
As a result of the Project implementation novel data will be acquired on behavior of Zr alloys vs neutron irradiation conditions; a step forward will be made in clarifying mechanisms of accelerated irradiation growth, creep, hydride formation and processes of suppression thereof as dependent on the structure-phase condition of alloys. In the end, this will allow scientifically founded principles to be suggested for providing long-term operation reliability of nuclear reactor core components.
Along with the experts of SSC RF VNIINM also experts from SSC RF NIIAR, RFNC VNIITF and IFM RAS UB shall participate in this Project.