BALANCE OF PLANT | STEAM GENERATOR CONTROLS
Steam generator controls analysis
The steam generator level control system is a key instrumentations and control subsystems to ensure the safe operation of nuclear power plants. However, it is one of the most complex subsystems with more than 80 components and multiple failure modes. A Boolean Logic Driven Markov Process (BDMP) model offers better reliability analysis and a better maintenance strategy than traditional methods
By Zhou Tianmi, Qin Feng, Qian Yugang Qian of the China Nuclear Power
Operation Technology Corporation, Ltd.,and Xia Linlu, and Zhou Shiliang of the North China Electric Power University School of Nuclear Science and Engineering
DIGITAL INSTRUMENTATION AND CONTROL SYSTEMS (DICS) are used widely in nuclear power plants (NPPs), and the reliability of DICS has a direct impact on the safety level of a nuclear plant. The steam generator (SG) is a key piece of equipment within nuclear island. Keeping water level within a reasonable range is one of the conditions to ensure the safe operation of the reactor and the steam turbine. Therefore, steam generator level control system (SGLCS) is one of the more important subsystems of DICS in an NPP and its reliability directly affects the safe operation of nuclear island. The Boolean Logic Driven Markov Process (BDMP) is a powerful dynamic reliability modeling method which can associate the Markov process with the leaf nodes of a fault tree, thus solving the problem that the fault tree approach is not suitable for describing the repairable model with a strong correlation of component faults and the problem of combination explosion of the Markov model. Electricite De France (EDF) developed the BDMP modeling software KB3 and
its quantitative analysis software YAMS, which have been widely used in the reliability analysis of various systems in power plants and power grids. However, as KB3 software is an internal software owned
by EDF, it is limited for export and only the education version can be applied in other countries. As a result, its modeling capabilities are greatly restricted. In this research a custom scripting language was defined to describe the BDMP model, and a converter program developed to transfer BDMP script into PRISM script, the latter is used to define the Markov model. The probabilistic model checker RPISM, which is widely used and recognized in the reliability field, was then used to carry out a quantitative analysis. The BDMP model of an SGLCS within an NPP was established and analysed using this method while at the same time, the analysis results were verified using KB3 (Version is 3.5.1) and YAMS software. Finally, the contribution of the unavailability of different parts of SGLCS to the total SGLCS is also obtained.
Above: Dynamic reliability analysis of the steam generator level control system could improve reliability 32 | August 2023 |
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