The study of the brittle fracture resistance in fusion areas between RPV STEEL 15H2NMFA grade 1 and austenitic padding
The authors investigate the brittle fracture resistance of PRV 15H2NMFA grade 1 steel. The study used sets of small-sized specimens and a set of standard specimens. It is shown that, using sets of small-sized specimens in mechanical tests to determine the brittle fracture resistance of RPV 15H2NMFA grade 1 steel, it becomes possible to increase the test volume in each batch by 8 times without significant changes in the design of irradiation devices and, therefore, initial irradiation parameters, thereby substantially expanding the database of test results for statistical processing.
The paper demonstrates the need for large-scale process simulation of conditions arising in weld joint zones that are inaccessible for direct testing, such as: (1) the welding zone between the base metal and the corrosion-resistant coating metal, (2) the welding area between the weld metal and the corrosion-resistant coating metal, and (3) the fusion area between the base metal, the weld metal, and the anticorrosive cladding metal.
Process simulation of the metal of fusion areas up to 0.5 mm wide (each is 100 μm in size) with an experimental electroslag refined (ESR) ingot of up to 300 mm long with a similar microstructure and variable chemical composition makes it possible (1) to examine at least 1000 small-sized impact specimens with a continuous distribution of the content of chemical elements in accordance with a certain law; and (2) to test these specimens and determine brittle fracture dangerous zones across fusion areas between the base metal and the anti-corrosive padding metal in the initial state or after subsequent irradiation at a given fluence rate and temperature.
- PNAE G-7-002-86 Rules of strength calculation for equipment and pipelines of nuclear power plants. Moscow. Energoatomizdat Publ., 1987, 525 p. (in Russian).
- PNAE G-7-008-89 Rules of the device and safe operation of equipment and pipelines of nuclear power plants. Moscow. FBU «NTC YaRB» Publ., 2012, 194 p. (in Russian).
- TU 0893-013-00212179-2003 Billets of 15H2NMFA, 15H2NMFA(A or 15H2NMFA grade 1 steels for reactor plant vessels, covers, and other components. Moscow. Information and Reference system «Tekhekspert» Publ., 2003, 26 p. (in Russian).
- Vishkarev O.M., Dub V.S., Loboda A.S., Shamardin V.K., Kobelev N.N., Kalugina I.I., Zubova T.N. Radiation resistance of 15H2NMFA steel. Trudy CNIITMASH. 1980, no. 157, pp. 4-6 (in Russian).
- Vishkarev O.M., Dub V.S., Loboda A.S., KashirskyYu.V., Shamardin V.K., Zubova T.N., Kalugina I.I., Kobelev N.N. Effect of impurities on radiation resistance of 15H2NMFA pearlitic steel. Trudy CNIITMASH. 1980, no. 157, pp. 19-24 (in Russian).
- RD EO 18.104.22.168.0920-2013. Calculation of brittle fracture resistance for VVER vessels at the design stage. Moscow. JSC «Rosenergoatom» Publ., 2013. 63 p. (in Russian).
- Dub A.V., Skorobogatykh V.N., Anosov N.P., Zharov V.V., Zubchenko A.S., Piminov V.A. Critical brittleness temperature dose-time relationships for predicting VVER-1000 RPV steel lifetime. Atomnaya Energiya. 2011, v. 110, iss. 3, pp. 123-130 (in Russian).
- Dub A.V., Skorobogatykh V.N., Anosov N.P., Zharov V.V., Zubchenko A.S., PiminovV.A., Shamardin V.K. The error in determining the critical brittleness temperature dose-time relationships for RPV steel welded joints in VVER design. VANT. Ser. Obespechenie bezopasnosti AES. 2011, iss. 30, Reaktornye ustanovki s VVER, pp. 126-141 (in Russian).
- Dub A.V., Skorobogatykh V.N., Anosov N.P., GordyukL.Yu., Zubchenko A.S., Shamardin V.K. Statistical modeling of realistic assessment of VVER-1000 RPV materials radiation embrittlement. VANT. Ser. Fizika atomnykh reaktorov. 2016, iss. 2, pp. 24-41 (in Russian).
- ASTM E2248-13 Standard Test Method for Impact Testing of Miniaturized Charpy V-Notch Specimens.
- Margolin B.Z., Nikolaev V.A., Yurchenko E.V., Nikolaev Yu.A., Erak D.Yu., Nikolaeva A.V. Analysis of the embrittlement of VVER-1000 RPV materials in the process of exploitation. Voprosy materialovedeniya. 2009, pp. 108-123 (in Russian).
- GOST 9454-78. Metals. Methods for testing the impact strength at low, room and high temperature. Moscow. Izdatel’stvo standartov Publ., 1994, 26 p. (in Russian).
- DIN EN ISO 148-1-2011 Metallic materials. Charpy pendulum impact test. Part 1: Test method (ISO 148-1:2009). German version EN ISO 148-1:2010, 35 p.
- GOST R ISO 148-1-2013. Metallic materials. Charpy pendulum impact test. Moscow. Standartinform Publ., 2014, 46 p. (in Russian)
- Markov S.I. Reference heat treatment methods for VVER type reactor vessel shells. Tyazhyoloe mashinostroenie. 2011, no. 8, pp. 12-16 (in Russian).
- GOST 5639-82. Steel and alloys. Methods for detection and determination of grain size. Moscow. IPK Izdatel’stvo standartov Publ., 1982, 21 p.
- Dub A.V., Skorobogatykh V.N., Anosov N.P., Zharov V.V., Zubchenko A.S., Piminov V.A., Shamardin V.K. Influence of the chemical and microstructural inhomogeneity of VVER RPV steels on critical brittleness temperature change under irradiation. Atomnaya Energiya. 2012, v. 112, no. 1, pp. 31-38 (in Russian).
- Anosov N.P., Krichivets Т.М, Novozhilov N.M., Zubchenko A.S, Tsikunov N.S. Express method for evaluating radiation resistance of weld joints as a function of chemical composition. Avtomaticheskaya svarka. 1982, no. 6 (351), pp. 62-63 (in Russian).
- Anosov N.P., Novozhilov N.M., Evseyev S.I., Amayev A.D., Kryukov A.M., Sokolov M.A. Estimating chemical composition dependence of weld joint metal radiation embrittlement. Avtomaticheskaya svarka. 1985, no. 10 (391), pp. 66-68 (in Russian).
- Surkov A.V., Novozhilov N.M., Anosov N.P. Method for producing an alloy of variable chemical composition: Authors’ Certificate of the USSR No. 642101, Bulletin No. 2, 15.01.1979.
- Anosov N.P., Novozhilov N.M., Zubchenko A.S., Kolesova T.N., Pecherin A.M., Shamardin V.K. Radiation resistance evaluation for 15H2NMFAA weld joint fusion zone metal using seams of variable chemical composition. Avtomaticheskaya svarka. 1990, no. 11 (452), pp. 7-10 (in Russian).
- RD EO 1.1.2.09.0789-2012. Procedure for VVER(1000 reactor vessel strength and lifetime calculation based on fracture toughness values determined by the surveillance specimens testing. Moscow. JSC «Rosenergoatom» Publ., 2012, 56 p. (in Russian).