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Science and Technology of Nuclear Installations
Volume 2017 (2017), Article ID 1064182, 12 pages
https://doi.org/10.1155/2017/1064182
Research Article

Specific Features of Structural-Phase State and Properties of Reactor Pressure Vessel Steel at Elevated Irradiation Temperature

1National Research Center “Kurchatov Institute”, Kurchatov Sq. 1, Moscow 123182, Russia
2National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute), Kashirskoe Highway 31, Moscow 115409, Russia
3State Research Center of the Russian Federation JSC RPA “CNIITMASH”, Sharikopodshipnikovskaya St. 4, Moscow 115088, Russia

Correspondence should be addressed to B. A. Gurovich

Received 1 February 2017; Revised 1 March 2017; Accepted 16 March 2017; Published 3 April 2017

Academic Editor: Keith E. Holbert

Copyright © 2017 E. A. Kuleshova et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper considers influence of elevated irradiation temperature on structure and properties of 15Kh2NMFAA reactor pressure vessel (RPV) steel. The steel is investigated after accelerated irradiation at 300°C (operating temperature of VVER-1000-type RPV) and 400°C supposed to be the operating temperature of advanced RPVs. Irradiation at 300°C leads to formation of radiation-induced precipitates and radiation defects-dislocation loops, while no carbide phase transformation is observed. Irradiation at a higher temperature (400°C) neither causes formation of radiation-induced precipitates nor provides formation of dislocation loops, but it does increase the number density of the main initial hardening phase—of the carbonitrides. Increase of phosphorus concentration in grain boundaries is more pronounced for irradiation at 400°C as compared to irradiation at 300°C due to influence of thermally enhanced diffusion at a higher temperature. The structural-phase changes determine the changes of mechanical properties: at both irradiation temperatures irradiation embrittlement is mainly due to the hardening mechanism with some contribution of the nonhardening one for irradiation at 400°C. Lack of formation of radiation-induced precipitates at = 400°C provides a small shift (17°C). The obtained results demonstrate that the investigated 15Kh2NMFAA steel may be a promising material for advanced reactors with an elevated operating temperature.