Calculated safety justification of the VVER-1000 reactor facility in the mode with the shutdown of one of the four MCPS during the operation at nominal power
The article considers results of the computational analysis of the process with the disturbance in operation of the VVER-1000 reactor facility, caused by the shutdown of one of the four Main Circulation Pumps (MCP-195). The calculations were made with the help of the CORSAR/GP software package developed by the Federal State Unitary Enterprise «Alexandrov RESE». This software package is the contour code which permits to calculate emergency situations taking into account the operation of various systems, including safety systems. The CORSAR/GP is certified and verified for the facilities with the water-cooled reactors including the VVER-1000.
The special computational scheme that takes into account the layout of main circulation circuit and its four-loop design was devised to calculate the process. The computational (also known as nodalization) scheme includes the pressuriser in one of the loops, boundary conditions simulating the second circuit, and nuclear reactor with its dynamics, feedbacks, and automation systems. Devised nodalization scheme of the first circuit of the VVER-1000 permits to add or exclude the operation of the protective safety systems and can also be used for the computational analysis of other disturbances. This nodalization scheme takes into account the reactor feedbacks on the fuel temperature and coolant temperature, as well as the void reactivity effect.
The calculations used the principle of moderate conservatism of estimates. In this case it is ensured by the choice of such core parameters that provide conservative results in terms of the process parameters values that determine the safe operation mode of the reactor facility (fuel temperature, boiling margin, etc.).
The calculations results include the estimates of the changes dynamics of the coolant heating in the core, changes of the nuclear peaking factor, the average temperature of the coolant at the outlet from the core, temperature of the fuel, and the change of the reactor power. The analysis of the results shows that the criteria describing the facility safety in the mode with the shutdown of one of the four MCPs during the operation at nominal power are fulfilled. The main contribution to the reactor facility safe operation is made by simulation of the automatic control system operation. The considerable, but less significant in the absolute value, contribution to the «keeping» of the facility within the safe operation limits is made by internal feedbacks (reactivity effects).
- Ivanov V.A. Exploitation of nuclear power plants. St. Petersburg. Energoatomizdat Publ., 1994, 384 p. (in Russian).
- Volkov Yu.V. Reliability and Safety of NPPs. Obninsk: IATE Publ., 1997, 102 p. (in Russian).
- Nigmatulin I.N., Nigmatulin B.I. Nuclear power plants. Moscow. Energoatomizdat Publ., 1986, 168 p. (in Russian).
- Baklushin R.P. NPP Operation. Vol. I. NPP operation in power systems. Vol. II. Radioactive waste handling. Moscow. NIYaU MIFI Publ., 2011, 304 p. (in Russian).
- Aminov R.Z., Khrustalev V.A., Dukhovensky A.S., Osadchiy A.I. NPP with VVER: Modes, characteristics, efficiency. Moscow. Energoatomizdat Publ., 1990, 264 p. (in Russian).
- Vygovsky S.B., Ryabov N.O., Semenov A.A., Chernov E.V., Bogachek L.N. Physical and structural features of nuclear power plants with VVER. Moscow. NIYaU MIFI Publ., 2011, 376 p. (in Russian).
- Bukrinsky A.M. Emergency transients at NPPs with VVER. Moscow. Energoizdat Publ., 1982, 142 p. (in Russian).
- Afrov A.M., Andrushechko S.A., Ukraintsev V.F., Vasil’ev B.Yu., Kosourov K.B., Semchenkov Yu. M., Kokosadze E.L., Ivanov E.A. VVER51000: the Physical bases of operation of, nuclear fuel safety. Moscow. Universitetskaya kniga, Logos Publ., 2006, 488 p. (in Russian).
- Leskin S.T., Shelegov A.S., Slobodchuk V.I. Physical Features and Design of the VVER-1000 Reactor. Moscow. NIYaU MIFI Publ., 2011, 116 p. (in Russian).
- RK KORSAR/V3 User’s manual. Federal Atomic Energy Agency. FSUE «A.P. Aleksandrov Scientific Research Technological Institute» Inv. No. T-1426. 273 p. (in Russian).
- RELAP5/MOD3 Code Manual. Code Structure, System Models, and Solution Methods. Idaho. National Engineering Laboratory, 1995, 418 p.
- Belikov V.V., Belikova G.V., Mosunova N.A. Thermohydraulic Code HYDRA. User’s Manual. Noscow. IBRAE RAN Publ., 2010, 127 p. (in Russian).
- MELCOR Computer Code Manuals. Available at: https://www.osti.gov/biblio/50939 (accessed May 15, 2018).
- Belozerov V.I., Zhuk M.M. Physics of the VVER51000 reactor and operational modes. Minsk. Dom Pressy Publ., 2012, 144 p. (in Russian).
- Margulova T.Kh. Nuclear Power Plants. Moscow. IzdAT Publ., 1994, 296 p. (in Russian).
- The Program Complex KORSAR/GP. The certification passport of the software № 263 dated September 23, 2009. Moscow. NTTs YaRB Publ., 2009 (in Russian).
- Migrov Yu.A., Korotaev V.G., Danilov I.G., Vladimirov A.V., Gudoshnikov A.N., Verbitsky Yu.G., Artemov V.G., Shemaev Yu.P. Improvement and modernization of the CC KORSAR/GP in the provision of safety analysis calculations for the VVER reactor. Proc. of the VIII-th International Scientific and Technical Conference «Ensuring the Safety of NPPs with VVER», Podol’sk, Russia, May 28-31, 2013. Podol’sk. JSC OKB GIDROPRESS Publ., 2013 (in Russian).