Improvement of Fracture Resistance Calculation Procedure for NPP Primary Equipment Components
ARTICLE PDF

Keywords

reactor pressure vessel, steam generator, baffle, elastoplastic deformation, radiation-induced swelling, fracture resistance, stress intensity factor, finite element method.

How to Cite

Kharchenko, V., Chirkov, A., Kobelsky, S., & Kravchenko, V. (2019). Improvement of Fracture Resistance Calculation Procedure for NPP Primary Equipment Components. Nuclear and Radiation Safety, (3(83), 26-34. https://doi.org/10.32918/nrs.2019.3(83).03

Abstract

The procedure of fracture resistance calculation for WWER primary equipment components has been improved. In particular, this refers to the reactor pressure vessel (RPV) and steam generators (SG) under normal operating conditions and emergencies. The developed calculation procedures and software make it possible to determine the significant effect of such factors as deformation stress history, residual technological heredity, analysis of temperature dependence of stress intensity factors for the postulated crack, regularity and density of the finite element mesh in the crack front on the assessment of WWER-1000 RPV fracture resistance.

The paper proposes the methodology for justifying the place and orientation of the postulated crack to obtain the most conservative assessment of fracture resistance in the area of RPV inlet nozzles. It is shown that elastoplastic calculations in the thermal shock simulation can help to improve estimates of RPV strength and lifetime. 

It was established that not taking into account the elastoplastic deformation history, residual technological stresses after heat treatment and corrosion effects can result in non-conservative assessment of fracture resistance of coolant header welding to SG PGV-1000M shell under normal operating conditions and emergencies.

The calculation methodology and software for assessing stress-strain state of in-vessel internals were improved taking into account state-of-the-art approaches to modeling of radiation-induced swelling deformations and dependence of metal mechanical peculiarities on exposure doses and temperature.

https://doi.org/10.32918/nrs.2019.3(83).03
ARTICLE PDF

References

1. Kharchenko, V.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2018). “The methods for calculating strength of WWER equipment components”. Institute for Problems of Strength, NAS of Ukraine, Kyiv, 293.

2. Kharchenko, V.V., Chirkov, A.Yu. (2016). “Some aspects of considering stress history in the analysis of RPV fracture resistance under thermal shock conditions”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, No. 5, 14-21.

3. Kharchenko, V.V., Piminov, V.A., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2013). “Elastoplastic fracture resistance analysis of NPP primary equipment components”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 45(4), 14-26.

4. Kharchenko, V.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I., Piminov, V.A., Akbashev, I.F. (2010). “Thermomechanical stress effect on WWER RPV under thermal shock conditions”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 42(1), 17-24.

5. Pressurized thermal shock in nuclear power plants: Good practices for assessment. IAEA-TECDOC-1627, Vienna, 2010.

6. Unified procedure for lifetime assessment of components and piping in WWER nuclear power plants (VERLIFE).

7. RD ÉO 0606-2005. Calculation procedure for brittle fracture resistance analysis of NPP WWER reactor pressure vessels (MRKR-SKhR-2004). St. Petersburg–Moscow, 2004.

8. MT-D.0.03.391-09. Procedure of strength and lifetime assessment for WWER reactor pressure vessels in operation. Energoatom Company, 2009.

9. Rules for Arrangement and Safe Operation of Equipment and Piping of Nuclear Power Installations (PNAE G-7-008-89). Moscow, 1990.

10. Stepanov, G.V., Kharchenko, V.V., Babutskii, A.I., Romanov, S.V., Voroshko, P.P., Kravchenko, V.I., Kobel’skyi, S.V., Radchenko, S.A., Feofentov, N.A., Kravchenko, I.V. (2003). “Calculation analysis improvement for stress-strain state and fracture resistance of coolant header welding to SG PGV-1000M shell”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 35(5), 536-544.

11. Kharchenko, V.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2018). “Peculiarities of the fracture strength design of the RPV branch pipe zone”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 50(4), 5-18.

12. Chirkov, A.Yu. (2019). “On the correctness of radiation swelling famous mathematical model taking into account stress effects in the problems of elastoplastic deformation mechanics”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers.

13. Kharchenko, V.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2017). “Improving the computer analysis of stress-strain state and fracture resistance of coolant header welding to SG PGV-1000M shell”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 49(3), 5-20.

14. Kharchenko, V.V., Chirkov, O.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2015). “Improvement of fracture strength calculation procedure for NPP equipment components”. Strength of Materials and Theory of Structures, 94, Kyiv, 59-74.

15. Kharchenko, V.V., Chirkov, A.Yu. (2013). “Modern approaches to the assessment of fracture resistance of WWER main equipment components”. Physical and Technical Problems of Modern Materials Science, Akademperiodyka, Kyiv, No. 1, 425–439.

16. Chirkov, A.Yu., Kharchenko, V.V., Kobel’skyi, S.V., Kravchenko, V.I., Piminov, V.A., Kurdin, M.E. (2013). “Stressed state of coolant header welding to SG PGV-1000M shell under normal operating conditions taking into account residual technological stresses”. Problems of Strength, 45(4), 98-106.

17. Kharchenko, V.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2012). “Improvement of elastoplastic calculation procedure for fracture resistance of NPP structural components”. Problems of Lifetime and Safety of Operation of Structures, Buildings and Machines, E.O. Paton Electric Welding Institute, NAS of Ukraine, Kyiv, 205-210.

18. Kharchenko, V.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I. (2011). “Peculiar features of the calculation assessment of fracture resistance of NPP RPV under thermal shock conditions”, Strength of Materials and Structural Components, Institute for Problems of Strength, NAS of Ukraine, Kyiv, 436-447.

19. Kharchenko, V.V., Stepanov, G.V., Chirkov, A.Yu., Kobel’skyi, S.V., Kravchenko, V.I., Babutskii, A.I., Zvyagintseva, A.A. (2009). “Investigation of the stress state of NPP RPV and SG considering the defects and thermomechanical stress history”. Problems of Lifetime and Safety of Operation of Structures, Buildings and Machines, E.O. Paton Electric Welding Institute, NAS of Ukraine, Kyiv, 177-180.

20. Kharchenko, V.V., Stepanov, G.V., Kravchenko, V.I., Kobel’skyi, S.V., Babutskii, A.L., Trunov‚ N.B., Piminov, V.A. (2009). “Stress redistribution in PGV-1000 header-steam generator connector during its loading after heat treatment”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 41(3), 251-256.

21. Kharchenko, V.V., Kobel’skyi, S.V., Kravchenko, V.I., Chirkov, A.Yu., Zvyagintseva, A.A. (2007). “Determination of stress intensity factor for semielliptical face cracks in WWER-1000 nuclear reactor by the solution of boundary problems of thermoelasticity on the basis of mixed FEM scheme”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 39(2), 138-143.

22. Stepanov, G.V., Kharchenko, V.V., Babutskii, A.I., Kravchenko, V.I., Kotlyarenko, A.A., Romanov, S.V., Trunov, N.B., Denisov, V.V., Piminov, V.A. (2006). The stress-strain state of the welding unit between the steam generator collecting channel and the case-connecting pipe under local heat treatment conditions”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 38(6), 595-600.

23. Kharchenko, V.V., Kobel’skyi, S.V., Kravchenko, V.I., Chirkov, A.Yu., Voroshko, P.P., Voronchuk, A.A. (2006). “Determination of stress intensity factors in the WWER-1000 RPV with a semi-elliptical crack under thermal shock using numerical and engineering calculation methods”, Problems of Lifetime and Safety of Operation of Structures, Buildings and Machines, E.O. Paton Electric Welding Institute, NAS of Ukraine, Kyiv, 177-180.

24. Kharchenko, V.V., Stepanov, G.V., Romanov, S.V., Voroshko, P.P., Orynyak, I.V. (2004). “Some topical issues of strength and life assessment for components of NPP equipment under thermomechanical stress”. Strength of Materials, New York: Kluwer Academic/Plenum Publishers, 36(1), 101-105.

25. A list of computer codes allowed for the use in the Energoatom to justify NPP safety issues, No. 526-р dated 03 June 2016.