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Information × Registration Number 0226U000680, (0120U102484) , R & D reports Title Strategy of life time extension for WWER Reactor Vessel. Research, analysis, methodology popup.stage_title Оцінка ресурсу корпусу реактора з підвищеним вмістом нікелю і марганцю з використанням методу Майстер кривої Head Revka Volodymyr M., Кандидат фізико-математичних наук Registration Date 14-01-2026 Organization Institute for Nuclear Research of NAS of Ukraine popup.description1 The purpose of this paper is to substantiate the possibility of using the test results of the survellance specimens for fracture toughness to evaluate the life time of WWER reactor vessels popup.description2 The study includes an assessment of reactor pressure vessel (RPV) metal embrittlement under long-term irradiation, as well as a comparison of experimental data on the shifts of transition temperatures TK and T0. The comparison showed that the radiation-induced shift ΔTK generally agrees with the shift of the reference temperature ΔT0. An analysis of the regulatory approach and the Master Curve methodology for evaluating the fracture toughness of RPV metal, performed by comparing fracture toughness curves, showed that the 5% lower-bound confidence limit of the Master Curve aligns best with the generalized PNAE G-7-002-86 dependence used for 15Kh2NMFA-A steel and its welds. Other regulatory KIC dependencies differ significantly and are less conservative compared with the 5% lower-bound Master Curve. When reassessing the critical brittleness temperature of the RPV metal using the reference temperature T0, the temperature RT0 was determined to index the regulatory fracture-toughness curve of SOU NAEK 177:2019 as a functional equivalent of the critical brittleness temperature TK0 for RPV materials in their initial condition. Using RT0 instead of TK0 may significantly reduce the conservatism of brittle-fracture resistance calculations and the level of conservatism becomes uniform for all materials. Using the Master Curve method, the service life of the reactor pressure vessel was evaluated. • Calculations of TK temperature in accordance with SOU NAEK 087:2023 showed that the radiation-limited service life of the KhNPP-1 reactor pressure vessel will be exhausted upon completion of the 54th fuel campaign (i.e., 54 effective years of NPP unit operation). Using RT0 for the initial state makes it possible to justify a significantly longer safe operating period for the reactor pressure vessel. • The proposed methodology may serve as a basis for amending regulatory documents concerning the integrity assessment and lifetime evaluation of WWER reactor pressure vessels. Product Description popup.authors VOLODYMYR STAKHOVSKYI YURII CHAIKOVSKYI LIUDMYLA CHYRKO OLEKSANDR TRYHUBENKO OLEKSANDR SHKAPIAK popup.nrat_date 2026-01-14 Close