ISPS equipment

 Project goal:

Provision of reliable and safe operation of Beloyarsk NPP Unit 4, which is achieved by protecting the power Unit from design-basis and beyond the 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 Beloyarsk NPP Unit 4, and jointly with control and protection system (CPS) it performs automatic reactor shut-down at an earthquake which exceeds the level of design-basis value.

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 transfer of signals, coming from SD, to initiating part of EP-PP (EP-PP IP);

ISPS provides the following:

  • generation of discrete emergency protection signals at exceeding of assigned emergency level of seismic influence threshold to EP-PP IP;
  • generation of discrete signals for start of registration (information archiving) at exceeding of assigned preventive level of seismic influence to EP-PP IP;
  • generation of analogue signals on acceleration values by coordinates X, Y, Z, and general analogue signals corresponding to absolute value of seismic acceleration to EP-PP IP;
  • generation of discrete signals of monitoring of SD good condition to EP-PP IP. 

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:

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.