JSC "STCD"

Diagnostics Center
URL: http://diaprom.com/
E-mail:
Address: office 329, Gazgoldernaya st. 14, Moscow 109518
Telephone/Fax: (495) 690-9195

Reactor Mode Diagnostic System of WWER-1000

Дерево событий при диагностировании течей

The basic functions of reactor mode diagnostic system are:

  • Real-time monitoring of primary circuit integrity. In case of loss of integrity, a diagnosis is issued containing the data on the leak location and rate i.e. indicating if it is a minor leak compensated by the reactor makeup system or uncompensated major leak;
  • Diagnostics of I&C standard measuring channels;
  • Monitoring of conduction of scheduled transient modes.

The early diagnostics of reactor system primary circuit defects and beyond-design condition is achieved by way of dedicated analysis of I&C analog and discrete signals. The logic model of power-generating unit equipped with WWER-1000 developed by JSC “Diaprom” is used for such analysis. The model is base d on the package of knowledge bases that contain the description of the sensors used, parameters calculated on the basis of the sensor readings, diagnostic thresholds and event trees making the system establish this or that diagnosis.

The model is implemented as the appropriate databases:

  • database "Analog signals";
  • database "Discrete signals";
  • database "calculated parameters";
  • database "derivatives";
  • database "functional links";
  • database "list of modes";
  • database "event trees";
  • database "diagnosis texts".

A sample of this model implementation as an event tree during leak diagnostics is given in Figure below. The diagnosis contains information about both the leak location and rate.

The specialty of reactor mode diagnostic system is the absence of necessity to equip the diagnostic equipment with additional technical control facilities. The diagnosis can be issued only on the basis of standard sensor readings. If additional signals from local diagnostic systems are used, the list of diagnoses issued by the system is broadened and the degree of the diagnoses reliability generally increases.

The reactor mode diagnostic system is an industrial computer or PC with the dedicated diagnostic software. The input data to be analyzed arrive from I&C of the power-generating unit through a dedicated hardware communication module or from the LAN. It is possible to receive data from the local diagnostic systems by way of dedicated equipment of signal conversion. The system structure is given in the Figure above.

The reactor mode diagnostic system software is developed to work under Microsoft Windows 98/NT/2000/XP.

The reactor mode diagnostic system software supports the following functions:

  • automatic real-time tracking of reactor system parameters with the issue of diagnoses and simultaneous archiving of diagnostic results and RS parameters;
  • post-event analysis using the recorded archives (to be used, for example, in case of analysis of abnormal situations or modes of reactor system operation);
  • event logging (startup, breaks, diagnosis issue etc.);
  • reporting in the format of common software solutions (Microsoft Word);
  • adjustment of the list of input parameters, diagnostic and alarm thresholds (setpoints);
  • event tree adjustment.

The latter two functions are not user defined functions and require expert’s participation.

The control of all basic functions (data base editing, reactor system parameter display, adjustment of initial system parameters) is performed from the main menu (see Figure above).

The view of the main format on the monitor during the operation of the reactor mode diagnostic system is given in the Figure below. On the left there is a list of I&C signals and the bar-graph representation. The green color in the bar graph means that the parameter value is close to the average design value in this RS operation mode, the yellow color means that the value is approaching the diagnostic threshold; the red color means that the diagnostic threshold is violated. Next to the bar-graph there is the parameter value and its full name according to I&C lists. On the right there is a list of parameters to be used to plot a graph (12 parameters at most). The graph is provided below the list of I&C parameters and is a graphical chart in the relative axes with the infinite time base. Below the graph there are data panels that display the system current status, list of parameters that exceed the diagnostic limits and texts of diagnoses.

The major stages of the system development included:

  • development of fault trees using expert knowledge of the reactor system operating modes procedure;
  • filling out data bases and knowledge bases;
  • optimization of major engineering solutions on a full-scale simulator of a power-generating unit equipped with WWER-1000 (VNIIAES).

At present the reactor mode diagnostic system is in the pilot operation at Unit №1 of Kalinin NPP. Over 400 I&C signals are used to perform the diagnostic procedure. A package of work had been accomplished to tailor the system according to the needs of particular I&C of the NPP Unit before the system was implemented.

Screen View of Main Format during Reactor Mode Diagnostic System Operation