Seismic instruments: article

Creation and operation experience of seismic protection system for a nuclear power plant
F. Arakelyan1
U. Zubko1
D. Levchenko2
1 “Atomseismicresearch” LTD, Moscow, Russia
2 Shirshov Institute of Oceanology RAS, Moscow, Russia
Journal: Seismic instruments
Tome: 53
Number: 3
Year: 2017
Pages: 20-30
UDK: 550.34
DOI: 10.21455/si2017.3-2.
Keywords: seismic monitoring, hardware maintenance, nuclear power station, Smolensk NPP, algorithms of operation, protection thresholds, communication interfaces
Аnnotation: The requirements for seismic resistance of nuclear power plants (NPPs) differ in their specific characteristics in comparison with similar requirements for other industrial facilities. This is connected with the need to protect not only the nuclear power plant itself, but also the environment from radiation hazards. According to special regulations, even if the seismicity of the nuclear power plant construction site is sufficiently small, it should be designed for the effect of the maximum calculated earthquake with peak acceleration for a given region. It should be noted that the principles of construction and operation of nuclear power plant seismic protection systems are fundamentally different from the systems used for current monitoring of seismic events. The main requirements for protection systems are the highly reliable detection of seismic events dangerous for the operation of nuclear power plants, ensuring timely informing the operators, reducing the likelihood of false alarms, excluding unauthorized access to the system. In 2014-2015 years “Atomseismicresearch” LTD has developed and put into trial operation a seismic protection system (SCZ-1M) of the Smolensk NPP power units. The system consists of six seismic groups: two groups per each power unit of the nuclear power plant. The group contains three independent seismic measuring channels, the sensors of which are spaced on the surface for distances up to 500 m around the corresponding power block. In each channel three components of the seismic signal are measured, the acceleration vector is calculated and compared with the set threshold. Signals exceeding the threshold are fed to the coincidence circuit with the triggering algorithm two out of three. Such a scheme excludes the occurrence of a false alarm when local action is applied to one of the paths. Elements of the system are chosen with high reliability and stability in time. The tracts of the system have passed the corresponding metrological certification. The system performs automatic continuous fault diagnosis. The programs for the system functioning and its diagnostics are independent and separated by hardware. All actions of the operator with the system are recorded. To exclude the possibility of external impact, the protection system CCZ-1M does not have an Internet connection. Special seismic signal simulators have been developed to test the system's operability when it is deployed.