Evaluation of VVER-1200/V-491 Reactor Pressure Vessel integrity during large break LOCA along with SBO using MELCOR 1.8.6
Main Article Content
Abstract
After Fukushima accident and stress test recommended by IAEA for existing reactors, higher safety requirements are enforced upon nuclear power plants during design extension and severe accident conditions. Based on those arguments, Vietnam Government requests a lot of effective safety solutions, in designs proposed for the nuclear power plants in Ninh Thuan province of Vietnam, which can prevent the accident progression toward severe accidents and mitigate severe accident consequences. One of safety requirements is related to delay time of core melt during design extension condition. Especially, if the worst case of accidents occurs, the reactor vessel integrity must be maintained at least 24 hours from the beginning of the accident. With the aim at investigation of Reactor Pressure Vessel (RPV) integrity, in this study, MELCOR 1.8.6 code is used to evaluate the integrity of RPV lower head for VVER-1200/V-491 reactor during a Large Break Loss of Coolant Accident (LBLOCA) in combination with Station Blackout (SBO) event. The study figures out several parameters related to melt down progress such as: rupture position and rupture timing, the amount of hydrogen generated. Availability of the second stage hydro-accumulators (HA2) in the VVER-1200/V-491 is assumed as an additional improvement to delay the timing of core melt as well as to maintain the vessel integrity for long-term.
Article Details
Keywords
VVER-1200/V-491, severe accident, LBLOCA
References
[2] B. Chatterjee, D. Mukhopadhyay, H. G. Lele, A. K. Ghosh, H. S. Kushwaha, P. Groudev, et al., "Analyses for VVER-1000/320 reactor for spectrum of break sizes along with SBO," Annals of Nuclear Energy, vol. 37, pp. 359-370, 2010.
[3] P. Groudev, B. Atanasova, B. Chatterjee, and H. G. Lele, ASTEC investigations of severe core damage behaviour of VVER-1000 in case of loss of coolant accident along with Station-Black-Out, Nuclear Engineering and Design, vol. 272, pp. 237-244, 2014.
[4] L. M. Toth, K. D. Pannell, and O. L. Kirkland, The Aqueous Chemistry of Iodine, presented at the Fission Product Behavior and Source Term Research, Utah, USA, 1984.
[5] K. Valery, Evolutionary development of safety systems, Vietnamese specialists, OKB Gidropress.
[6] Risk Engineering Ltd., Introduction in VVER technologies, Vietnam Atomic Energy Institute (VINATOM), Sofia, Bulgari, 2012.
[7] G. M. Hoang, K. N. Nguyen, T. C. Tran, and H. V. Le, Capability analysis of passive systems in typical design extension conditions for nuclear reactor VVER-1000/V392, Journal of Science and Technology, vol. 52 (2C), pp. 81-92, 2014.
[8] S. Dickinson and H. E. Sims, Modifications to the INSPECT Model, presented at the 4th OECD Workshop on Iodine Chemistry in Reactor Safety, Switzerland, 1996.
[9] Sandia National Laboratories, MELCOR computer code manuals, Ver.1.8.6, Rev. 3 vol. NUREG/CG 6119, 2005.
[10] EVN, Chapter 7 - Feasibility Study Safety Analysis Report for Ninh Thuan 1 NPP in the Socialist Republic of Vietnam, Vietnam, 2015.
[11] K. Mancheva, MELCOR analysis, PutraJaya, Malaysia: Risk Engineering Ltd, Bulgaria, 2015.