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A.V. Kozlov , I.A. Portnykh, V.L. Panchenko

FSUE « INM » , 624250, Box 29, Zarechny , Sverdlovsk region , Russia. Corresponding author. fax: +7-34377-33396; e-mail: sfti@uraltc.ru, AlexTIM@uraltc.ru. A.V. Kozlov , I.A. Portnykh, V.L. Panchenko. INM.

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A.V. Kozlov , I.A. Portnykh, V.L. Panchenko

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  1. FSUE «INM», 624250, Box 29, Zarechny, Sverdlovsk region, Russia Corresponding author. fax: +7-34377-33396; e-mail: sfti@uraltc.ru, AlexTIM@uraltc.ru A.V. Kozlov, I.A. Portnykh, V.L. Panchenko INM A model of influence of radiation damage rate on formation and evolution of radiation defects in austenitic steels.

  2. 2 Results of fast neutron reactor irradiation G  10-6dpa/s Results of an accelerating irradiation G ≥ 10-4dpa/s Fast neutron reactor G  10-6dpa/s Thermal reactor G  10-810-7dpa/s Correctness ? Introduction predict predict predict

  3. 3 The purpose of the work • Creation of quantitative model of influence of radiation damage rate on both formation and evolution of radiation defects in austenitic steels and its experimental checkout.

  4. Basic positions of model 4 Enteringrate ofpoint defectfrom cascade to matrix: Change of point defectconcentration in matrix: Whereх - coefficient of point defect get out from cascade area to matrix;  -cascade efficiency; G – irradiation damage rate; t – current value of time; x- diffusion time of х-typepoint defect (x=i– for interstitials,x=v– for vacancies).

  5. 5 Middle Temperature Irradiation (MTO-2) i –mobile - dissociate from cascade areas and freely diffuse in matrix (i=1); v -remain in cascade formation area, transformed into compact energy-binding configurations - vacancy clusters (v=0). i –mobile - dissociate from cascade areas and freely diffuse in matrix; v -dissociate from clusters and diffuse in matrix. Low Temperature Irradiation (LTO) Basic positions of model; examined temperature range Объект исследования

  6. Low Temperature Irradiation (LTO). Model. 6 Diffused interstitials migrate to three type of sink: grain boundary, dislocations and inside clusters. Grain boundary Dislocation

  7. Low Temperature Irradiation (LTO). Model. 7 Cluster after thermodynamic stabilization Interstitial-vacancy recombination process leads to cluster vanish. The cluster size doesn’t change at the recombination process. Cluster evolution

  8. Calculation results 8 Formula for diffusion time of interstitials: Where dg – grain size; d - dislocation density; nc – clusters concentration; rc – average size of clusters. For ChS-68 steel at G210-7 dpa/s and Т300 К i10-1 s

  9. Calculation results 9 Interstitials concentration: Fig. 1.Time dependence of interstitials concentration in ChS-68 steelat neutron irradiationat G210-7 dpa/s andТ300 К.

  10. Calculation results 10 Average lifetime of clusters: Where m0- average amount of vacancies in cluster at formation moment. For ChS-68 steel at G210-7 dpa/s and Т310 К Average lifetime of clusters 103-104с

  11. Calculation results 11 Clusters concentration: Clusters generation rate: Fig. 2.Time dependence of radiation clusters concentration in ChS-68 steelat neutron irradiationat G210-7 dpa/s andТ300 К.

  12. Calculation results 12 Fig. 3.Time dependence of average vacancy concentration in cluster for various damage dose rates in ChS-68 steelat neutron irradiation at Т310 К.

  13. 13 Calculation results ! The irradiation with lower damage dose rate leads to more strong radiation damages, than at higher damage dose rate (at the same damage dose).

  14. Low Temperature Irradiation (LTO) – Experimental data 14 The experimental examinations after irradiation and post annealing of two austenitic steels ChS-68 (16Cr-15Ni-2Mo-2Mn-Si-Ti) in a state after final 20 % cold work and EI-844 (16Cr-15Ni-2Mo-Mn-Si-Nb) in austenitic state were carried out. The irradiation was carried out at temperature 310 K to damage dose 0.0007 dpa for ChS-68 and 0.007 dpa for EI-844 steels.

  15. Comparing calculated and experimental data 15 Table 1 – Relative sizechanges (%) of ChS-68 and EI-844 steel specimens irradiated at temperature 310 К, caused by an annealing of radiation clusters.

  16. Middle Temperature Irradiation (MTO). Model. 16 Average diffusion time of interstitials and vacancies was calculated by the same methodic: Formulas for vacancy diffusion time and interstitial diffusion time was obtained. For ChS-68 steel at G110-6 dpa/s and Т700 К v103 s,i10-3 s

  17. Middle Temperature Irradiation (MTO). Model. 17 5,0 4,5 4,0 3,5 3,0 2,5 600 K 2,0 700 K 1,5 1,0 800 K 0,5 0,0 -8 -7 -6 -5 -4 Vacancy concentration, ×10-5 LgG Fig. 6.Dependence of quasi-equilibrium vacancy concentration on irradiation damage rate in ChS-68 steelirradiated at different temperatures.

  18. Middle Temperature Irradiation (MTO). Model. 18 50 45 40 35 30 25 600 K 20 700 K 15 10 800 K 5 0 -8 -7 -6 -5 -4 Interstitials concentration, ×10-10 LgG Fig. 7.Dependence of quasi-equilibrium interstitials concentration on irradiation damage rate in ChS-68 steelirradiated at different temperatures.

  19. Middle Temperature Irradiation (MTO). Model. 19 100 80 60 600 K 40 700 K 800 K 20 0 -8 -7 -6 -5 -4 Cve/Cie, ×105 LgG Fig. 8.Dependence of ratio vacancies concentration to interstitials concentration on irradiation damage rate in ChS-68 steelirradiated at different temperatures.

  20. 20 Middle Temperature Irradiation (MTO). Model. ! It is incorrectly to use plainly the results obtained at high damage dose rate irradiation for prediction influence of low damage dose rate irradiation on material structure changes.

  21. 21 Conclusions • The quantitative model of point defect evolution is created. It allows in any cases to describe point defect evolution in dependence on temperature, dose and damage dose rate of neutron irradiation. • The dependences of interstitials concentration, vacancy clusters concentration and average vacancy amount in a cluster are obtained for low temperature and low dose irradiation. It’s shown irradiation at low damage dose rate lead to more strong distraction than irradiation at high damage dose rate when irradiation doses are equal. • The calculation results of size changes of EI-844 and ChS-68 steel specimens irradiated at 310 K to low damage dose and annealed are correlate to the obtained experimental data.

  22. 22 Conclusions • It’s shown by the model vacancy and interstitial quasi-equilibrium concentrations are established at irradiation temperatures 600 – 800 K during the fix time. The time is about 1 hour for vacancies and 10-3 s for interstitials in ChS-68 steel irradiated in fast neutron reactor. • The dependences of vacancy and interstitial concentrations on damage dose rate for irradiation temperatures 600 K, 700 K, 800 K were obtained. It’s shown the less damage dose rate leads to stronger radiation swelling.

  23. INM Thank you for attention and patience

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