Radiation-induced structure of austenitic steels with different nickel content under neutron irradiation in SM-3 and BOR-60 reactors

Comparative studies of the radiation-induced structure of austenitic steels with a nickel content of 10, 20 and 25 wt.%, irradiated sequentially in the SM-3 and BOR-60 reactors, as well as to higher damaging doses in the BOR-60 reactor, have been carried out. The phase composition, dislocation structure, pores, and radiation-induced segregations at grain boundaries were studied by high-resolution analytical methods of transmission electron microscopy, scanning electron microscopy, and atomic probe tomography. The formation of radiation-induced phase precipitates based on nickel has been established, and its volume fraction correlates with the level of radiation-induced segregations, and increases, the higher the nickel content in the steel. The values of barrier strength factors for radiation-induced structural elements in the studied steels are adjusted by calculation and experiment, which makes it possible to determine their contribution to radiation hardening.It is shown that the largest contribution to radiation hardening as a result of neutron irradiation in BOR-60 at high irradiation temperature up to 29 dpa is made by large radiation-induced precipitates of (G + γ') phases. It is shown that with an increase in the damaging dose, the main factor limiting the performance of internal devices will be radiation swelling, since the contribution to the change in properties from radiation-induced phases and radiation defects will not increase due to their density reaching saturation. Steel with 25 wt.% Ni exhibits the lowest level of swelling at high radiation doses, which makes it possible to consider it as a material-candidate for internals for promising VVER reactors with higher temperatures and longer service life.

1. Margolin , B.Z., Kursevich , I.P., Sorokin , A.A., Vasina , N.K., Neustroev, V.S., K voprosu o radiatsionnom raspukhanii i radiatsionnom okhrupchivanii austenitnykh staley. Ch. 2: Fizicheskie i mekhanicheskie zakonomernosti okhrupchivaniya [On the issue of radiation swelling and radiation embrittlement of austenitic steels. Part 2: Physical and mechanical regularities of embrittlement], Voprosy Materialovedeniya, 2009, No 2(58), pp. 99–111.

2. Kuleshova, E.A., Fedotova , S.V. et al., Issledovanie sostoyaniya metalla vnutrikorpusnykh ustroystv reaktora VVER posle ekspluatatsii v techenie 45 let. Ch. 3: Mikrostruktura i fazovy sostav [Investigation of the state of the metal of internal devices of the VVER reactor after operation for 45 years. Part 3: Microstructure and phase composition], Voprosy Materialovedeniya, 2020, No 3(103), pp. 157–180.

3. Kursevich, I.P., Karzov, G.P., Margolin, B.Z., Sorokin, A.A., Teplukhina, I.V., Printsipy legirovaniya novoy radiatsionno-stoykoy austenitnoy stali dlya VKU VVER-1200, obespechivayushchey ikh bezopasnuyu ekspluatatsiyu ne menee 60 let [Principles of alloying new radiationresistant austenitic steel for VCU VVER-1200, ensuring their safe operation for at least 60 years], Voprosy Materialovedeniya, 2012, No 3(71), pp. 146–160.

4. Karzov, G.P., Margolin, B.Z., Sorokin, A.A., Fedorova, V.A., Osnovnye mekhanizmy radiatsionnogo povrezhdeniya materialov VKU i materialovedcheskie problemy ikh dlitelnoy ekspluatatsii [Main mechanisms of radiation damage to materials for VVER reactor internals and material science problems of their long-term operation], URL: www.gidropress.podolsk.ru/files/proceedings/mntk2015/autorun/article117-ru.htm (reference date 09/12/2022)

5. Gurovich, B.A., Kuleshova, E.A., Frolov, A.S. et al., Investigation of high temperature annealing effectiveness for recovery of radiation-induced structural changes and properties of 18Cr– 10Ni–Ti austenitic stainless steels, J. Nucl. Mater., 2015, V. 465, pp. 565–581.

6. Piminov, V.A., Evdokimenko, V.V., Nadezhnost na ves srok ekspluatatsii [Reliability for the entire service life], Rosenergoatom, 2015, No 2, pp. 16–19.

7. Margolin, B., Sorokin, A., Pirogova , N. et al., Analysis of mechanisms inducing corrosion cracking of irradiated austenitic steels and development of a model for prediction of crack initiation, Engineering Failure analysis, 2020, V. 107, p. 104235.

8. Pokor, C., Massoud, J.P., Wintergerst, M., Toivonen, A., Ehrnsten, U., Karlsen, W. Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment, Proceedings of the Conference “Fontevraud 7: Contribution of materials investigations to improve the safety and performance of LWRs”, France, 2011, Report Number INIS-FR--11-0585.

9. Bosch , R.W., Vankeerberghen , M., Gérard , R., Somville, F., Crack initiation testing of thimble tube material under PWR conditions to determine a stress threshold for IASCC, J. Nucl. Mater., 2015, V. 461, pp. 112–121.

10. Margolin , B., Sorokin , A., Smirnov, V., et al., Physical and mechanical modelling of neutron irradiation effect on ductile fracture. Part 1: Prediction of fracture strain and fracture toughness of austenitic steels, J. Nucl. Mater., Elsevier, 2014, V. 452, No 1–3, pp. 595–606.

11. Margolin , B., Sorokin , A., Shvetsova, V., et al., The radiation swelling effect on fracture properties and fracture mechanisms of irradiated austenitic steels. Part 1: Ductility and fracture toughness, J. Nucl. Mater., 2016, V. 480, pp. 52–68.

12. Garner, F.A., Radiation damage in austenitic steels, Comprehensive Nuclear Materials, 2012, V. 4, pp. 33–95.

13. Voevodin, V.N., Neklyudov, I.M., Evolution of the structure phase state and radiation resistance of structural materials, Kiev: Naukova Dumka, 2006.

14. Margolin , B., Pirogova , N., Sorokin , A., Morozov, A., Correlation between grain boundary strength determined by impact test of miniature specimen and stress corrosion cracking resistance of irradiated austenitic steels used for the internals of WWER-type and PWR-type nuclear reactors, Engineering Failure analysis, 2021, V. 127, p. 105544.

15. Kurata, H., Isoda, S., Kobayashi, T., Chemical Mapping by Energy-Filtering Transmission Electron Microscopy, J. Electron Microsc. (Tokyo), 1996, V. 45, No 4, pp. 317–320.

16. Laver gne, J.-L., Martin, J.-M., Belin, M., Interactive electron energy-loss elemental mapping by the Imaging-Spectrum method, Microsc. Microanal. Microstruct., 1992, V. 3 (6), pp. 517–528.

17. Williams, D.B., Carter, C.B., Transmission Electron Microscopy: A Textbook for Materials Science, 2009.

18. Goldstein, J.I., et al., Scanning electron microscopy and X-ray microanalysis, 3rd ed., New York: Springer, 2003.

19. Sindo, D., Oikava, T., Analiticheskaya prosvechivayushchaya elektronnaya mikroskopiya [Analytical transmission electron microscopy], Moscow: Tekhnosfera, 2006.

20. Yakoubovsky, K., et al., Thickness measurements with electron energy loss spectroscopy, Microsc. Res. Tech., 2008, V. 71, No 8, pp. 626–631.

21. Frolov, A.S., Krikun , E.V., Prikhodko, K.E., Kuleshova , E.A., Development of the DIFFRACALC program for analyzing the phase composition of alloys, Crystallogr. Reports., 2017, V. 62, No 5, pp. 809–815.

22. Miller, M.K., Forbes, R.G., Atom-Probe Tomography, Boston: Springer, 2014.

23. Larson, D.J., et al., Local Electrode Atom Probe Tomography: A User’s Guide, Springer, 2013.

24. Marquis, E.A., Hyde, J.M., Applications of atom-probe tomography to the characterisation of solute behaviours, Mater. Sci. Eng. R Reports, 2010, V. 69, No 4–5, pp. 37–62.

25. Hyde, J.M., Marquis, E.A., Wilford, K., et al., A sensitivity analysis of the maximum separation method for the characterisation of solute clusters, Ultramicroscopy, 2011, V. 111, No 6, pp. 440–447.

26. Li, X., The Effect of the Stacking Fault Energy on the Post-Irradiation Behavior of Austenitic Stainless Steels Under Pressurized Water Reactor Conditions, SCK CEN’s Public Institutional Repository, 2009.

27. Kuleshova, E., Fedotova, S., Gurovich. B., et al., Microstructure degradation of austenitic stainless steels after 45 years of operation as VVER-440 reactor internals, J. Nucl. Mater, 2020, V. 533.

28. Margolin, B.Z., Varovin, A.Ya ., Minkin, A.J., et al., Opredelenie izmeneniya geometrii vygorodki reaktora VVER-1000 v protsesse ekspluatatsii. Raschet i izmerenie [Determination of changes in the geometry of the VVER-1000 reactor baffle during operation. Calculation and measurement], Voprosy Materialovedeniya, 2015, No 3(83), pp. 182–196.

29. Kenik , E.A., Busby, J.T., Radiation-induced degradation of stainless steel light water reactor internals, Mater. Sci. Eng. R Reports, 2012, V. 73, No 7–8, pp. 67–83.

30. Margolin, B.Z., Pirogova, N.Ye., Potapova, V.A., Issledovanie mekhanizmov korrozionnogo rastreskivaniya stali dlya VKU VVER na osnove imitatsionnykh ispytaniy [Investigation of the mechanisms of corrosion cracking of steel for VCU VVER based on simulation tests], Voprosy Materialovedeniya, 2017, No 4(92), pp.193–218.

31. Pechenkin, V.A., Chernova, A.D., Molodtsov, V.L., et al., Radiatsionnoindutsirovannaya segregatsiya i svoystva konstruktsionnykh materialov pod oblucheniem [Radiation-induced segregation and properties of structural materials under irradiation], Yadernaya fizika i inzhiniring, 2013, V. 4, No 5, pp. 443–461.

32. GOST R59429–2021: Ustroystva vnutrikorpusnye vodo-vodyanogo energeticheskogo reaktora. Raschet na prochnost na stadii proektirovaniya [In-vessel devices of pressurized water power reactor. Strength calculation at the design stage].

33. Zinkle, S.J., Maziasz, P.J., Stoller, R.E., Dose dependence of the microstructural evolution in neutron-irradiated austenitic stainless steel, J. Nucl. Mater, 1993, V. 206, No 2–3, pp. 266–286.

34. Shim, J.-H., Povoden -Karadeniz, E., Kozeschnik, E., et al., Modeling precipitation thermodynamics and kinetics in type 316 austenitic stainless steels with varying composition as an initial step toward predicting phase stability during irradiation, J. Nucl. Mater, 2015, V. 462, pp. 250–257.

35. Pechenkin , V.A., Epov, G.A., The influence of radiation-induced segregation on precipitate stability in austenitic steels, J. Nucl. Mater, 1993, V. 207, pp. 303–312.

36. Mamivand, M., Yang, Y., Busby, J., et al., Integrated modeling of second phase precipitation in cold-worked 316 stainless steels under irradiation, Acta Mater. Elsevier Ltd., 2017, V. 130, pp. 94–110.

37. Kuleshova, E.A., et al., Precipitation kinetics of radiation-induced Ni–Mn–Si phases in VVER-1000 reactor pressure vessel steels under low and high flux irradiation, J. Nucl. Mater., 2021, pp. 153091.

38. Ke, H., Wells, P., Edmondson, P.D., et al., Thermodynamic and kinetic modeling of Mn–Ni–Si precipitates in low-Cu reactor pressure vessel steels, Acta Mater. Elsevier Ltd., 2017, V. 138, pp. 10–26.

39. Lambrecht, M., Meslin, E., Malerba, L., et al., On the correlation between irradiation-induced microstructural features and the hardening of reactor pressure vessel steels, J. Nucl. Mater., 2010, V. 406, No 1, pp. 84–89.

40. Lucas, G.E., The evolution of mechanical property change in irradiated austenitic stainless steels, J. Nucl. Mater., 1993, V. 206, No 2–3, pp. 287–305.

41. Tan , L., Busby, T.J., Formulating the strength factor α for improved predictability of radiation hardening, J. Nucl. Mater., 2015, V. 465, pp. 724–730.

42. Razorenov, S.V., Gark ushin, G.V., Astafurova, E.G., et al., Vliyanie plotnosti dislokatsii na soprotivlenie vysokoskorostnoy deformatsii i razrusheniyu v medi M1 i austenitnoy nerzhaveyushchey stali, Fizicheskaya mezomekhanika, 2017, No 20 (4), pp. 43–51.

43. Kocks, U.F., The relation between polyrystal deformation and single-crystal deformation, Metall. Mater. Trans., 1970, V. 1, pp. 1121–1143.

44. PNAE G-7-002–86: Normy rascheta na prochnost oborudovaniya i truboprovodov atomnykh energeticheskikh ustanovok [Standards for calculating the strength of equipment and pipelines of nuclear power plants], Moscow: Energoatomizdat, 1989.

45. Patent RF RU 2633408C1: Margolin, B. Z., Gulenko, A. G., Sorokin, A. A. et al., Radiatsionno-stoykaya austenitnaya stal dlya vnutrikorpusnoy vygorodki VVER [Radiation-resistant austenitic steel for VVER inner-vessel baffle], 2019.