Assessment of risks of damage of welded joint of manifold and steam generator connection sleeve for NPP with VVER
The problems of determining the risks of failure of equipment of operating NPP and, particularly, plants with a long service life are highly relevant especially in association with approaching expiration of the design service life (25 – 30 years) of power units of NPPs in the RF, as well as with extended design service life of the newly built power units (up to 60 years). Expiration of the design service life of existing NPPs, as well as extension of design service life of the newly built power units predetermine the need to develop new approaches in order to ensure reliable and safe operation of the most critical elements of the thermal and mechanical equipment and pipelines.
One of such elements is the welded junction (WJ) zone No. 111 where hot collector is welded to the vessel of steam generator where development of operational defects is possible, and these defects are systematic in nature and affect safety of operation of the whole power unit.
Statistics of failures in WJ zone No. 111 between the hot and cold manifolds of the steam generator to the DU-1200 pipeline for VVER reactors is given in the present paper. Classification of approaching limiting conditions of failures is suggested for WJ zone No. 111 of the steam generator. Calculation of risk for the power unit in case of development of one of the limiting conditions was performed. The size of losses in cases of damage of the welding joint of a manifold with steam generator connection sleeve in a zone WJ No. 111 is considerable. The probability of emergence of unacceptable defects within zone WJ No. 111 remains to be very high and requires undertaking measures for controlling the moment of their initiation and development.
- Bakirov M.B., Povarov V.P., Levchuk V.I., Gromov A.F. Development of the technology of continuous acoustic emission monitoring of operational damageability of metal of sensitive equipment of nuclear power plants. Izvestiya vuzov. Yadernaya Energetika. 2014, no. 3, pp. 15-23 (in Russian).
- General provisions of safety of nuclear power plants, NP-001-15 (in Russian).
- Rules for the Construction and Safe Operation of equipment and pipelines of atomic power stations, NP 089-15 (in Russian).
- The main requirements for the extension of service life of the nuclear plant power unit, NP-017 - 2000 (in Russian).
- Ostreykovsky V.A., Smolin D.I. Kolichestvennaya ocenka veroyatnostey ishodnykh sobytij pri analize riska ot eksplustacii atomnyh stancij. [The quantitative assessment of probabilities of initial events in the analysis of risk from operation of nuclear power plants]. Severny region: nauka, obrazovanie, kul‘tura. 2013, no. 2, pp. 11-21 (in Russian).
- Levchuk V.I. Raschetno-experimentalny analiz vliyaniya termosilovykh vozdeystviy na povrezhdeniye uzla privarki kollektora teplonositelya k korpusu parogeneratora PGV-1000M. Diss. Kand. techn. nauk [The calculated and experimental analysis of influence of thermal power impacts on the damage of welded joint of manifold of the heat carrier to a PGV– 1000M steam generator housing. Cand. Sci. (Eng.) dissertation]. Moscow, 2015. 136 p. (in Russian).
- Ostreykovsky V.A. Technogenic risk: Introduction to the theory. Surgut. IC SurGU Publ., 2009, 63 p. (in Russian).
- Ostreykovsky V.A., Shvyryaev Yu.V. Safety of nuclear power plants: Probability analysis. Moscow. Fizmatlit Publ., 2008, 353 p. (in Russian).
- Ostreykovsky V.A., Saakyan S.P. Model of determination of probabilities of initial events of accidents by methods of the theory of accidents. In: Proc. of the IX International Scientific School MA SR – 2010, pp. 123-126. Saint-Petersburg. SUAI Publ., 2010, 566 p. (in Russian).
- Makhmutov N.A., Frolov K.V., Dragunov Yu.G. Analysis of risk and increase of safety of light water power reactors. Eds. N.A. Makhmutov, M.M. Gadenin. Moscow. Nauka Publ., 2009. 499 p. (in Russian).
- Ostreykovsky V.A., Saakyan S.P. Technogenic safety and risk from operation of nuclear power plants. Obninsk. IATE NRNU MEPhI Publ., 2011, 160 p. (in Russian).
- Ostreykovsky V.A. Mathematical models of the theory of technogenic risk. Surgut. IC SurGU Publ., 2012, 253 p. (in Russian).
- Venttsel E.S. Probability theory. Moscow. Vysshaya shkola Publ., 1998, 576 p. (in Russian).
- Bakhmetyev A.M., Samoylov O.B., Usynin G.B. Methods of assessment and safety of NPP. Moscow. Energoatomizdat Publ., 1988, 136 p. (in Russian).
- Klimov A.N. Nuclear physics and nuclear reactors. Moscow. Energoatomizdat Publ., 2002, 464 p. (in Russian).
- Begun V.V. Probability analysis of safety of nuclear power plants. Kiev. NTTU KPI Publ., 2000, 568 p. (in Russian).
- Federal Law of the RF No. 170-FZ dated 21 November, 1995 «On the use of atomic energy» with modifications and amendments (in Russian).
- Executive Order of the Federal Service for Environmental, Technological and Nuclear Oversight of No. 502 dated 7 December, 2015 «On the establishment of federal regulation and rules of use of atomic energy of «The rules of monitoring of the main metal, welded joints and the built-up surfaces during operation of an equipment, pipelines and other elements of nuclear power plants» (in Russian).
- Federal regulations and rules of use of atomic energy PNAE G-7-009-89 «Equipment and pipelines of atomic power stations. Welding and weld deposition. Main provisions» with modifications and amendments (in Russian).
- Guidance documents NP-006-98 and PNAE G-01-036-95 «Requirements on the subject matter of safety justification reports for NPPs equipped with VVER reactors» (Resolution of Gosatomnadzor of the Russian Federation No. 7 dated May 3, 1995) (in Russian).