Provision of reliable and safe operation of power Units Nos.1, 2 of Novovoronezh NPP-2, which is achieved by protecting the power Unit from design-basis accidents, occurring in the result of seismic influences (earthquakes), by reactor plant transferring into safe state in order to prevent an accident at the early stage.
ISPS is a completed part of automated process control system (APCS) of power Units Nos.1, 2 of Novovoronezh NPP-2, and jointly with control and protection system (CPS) it performs generation of signals for automatic reactor shut-down at an earthquake which exceeds the level of design-basis value.
ISPS is designed for power Units Nos.1, 2 of Novovoronezh NPP-2 with four-loop reactor plant with water-water power reactor WWER-1200 (V392-M) of electric power equal to 1200 MW.
ISPS consists of two independent sets.
Composition of each set includes the following devices and units:
- Three channels for measurement of seismic influences, implemented on the base of three-component seismic sensors SD4;
- Three commutation units (BKK) for multiplication and transfer of signals, coming from SD, to transport-technological equipment (TTE), to data display and logging hardware (DDLH) and equipment of TELEPERM XS (TXS);
ISPS provides the following:
- measurement of seismic influences on reactor plant (RP);
- generation of discrete signals of emergency protection (EP) at exceeding of assigned emergency level of seismic influence threshold;
- generation of discrete signals for start of registration at exceeding of assigned preventive level of seismic influence;
- generation of analogue signals on acceleration values by coordinates X, Y, Z, and general analogue signals corresponding to absolute value of seismic acceleration;
- generation of discrete signals on failure of ISPS channels.
The range of analogue signals is (4-20) mA. The type of discrete signals: group of relay commutating contacts at current within the range up to 100 mA and supply voltage of 24 V.
Structural diagram of ISPS set:
Each ISPS channel performs diagnostics of intrinsic technical means. At failure of channel (at malfunction), at disconnection of electric supply the signal, equivalent to emergency protection signal, is generated.