Because of the physical and moral ageing of the core monitoring hardware and software tools, an upgrading process has been initiated in 1991 by the Paks NPP. In the framework of this process the primary data acquisition system Hindukus has been replaced by a set of VME-based redundant systems called PDA (provided by Comproject Ltd, Budapest). Five PDA crates, each with a high performance Motorola processor, collect the measured data, the most important ones reaching two crates in parallel. All standard incore measurements along with those from the primary and secondary loops that are important from core monitoring purposes are available for the system. More than 700 analogue and 360 discrete signals are processed once in every 2 seconds. A two way data connection with the plant process computer ensures the transfer of certain data not available in the other system.
Two MicroVAX 3100 computers host the VERONA-u core monitoring software, both in network connection with the five PDAs. (The communication software was developed by Akribia Ltd, Budapest.) The two hosts are full substitute to each other, should the active host break down for any reason the other (hot standby) computer takes over the entire functioning of the system. As much as eight graphical workstations can be served by a
system at a reactor unit (two in the control room, two in the computer centre and four remote stations anywhere in the plant's network). The four local stations are dedicated to the given unit, the remote stations can reach any of the units.
The hardware configuration of the VERONA-u system in a reactor unit
Two remote VERONA systems (VERONA-r and VERONA-t) serve independent developing, experimental and planning purposes at the Reactor Physics and at the Digital Systems Departments, resp. of the NPP. These remote systems can obtain on-line data from any unit, or can run over recorded data in the standard "archives replay" operational mode of VERONA-u. The
plantwise VERONA configuration thus includes 10 MicroVAX computers, 20 workstations and 20 primary data acquisition PDAs, all connected via a local area network. An independent full capacity system, the VERONA-s is running in co-operation with the full scope training simulator of the plant.
The role of the VERONA-u system in the plantwise information system
Advanced programming, database handling and user interface tools have been exploited during the development of the system. A great part of the core analysis calculations has been developed in the NPP Reactor Physics Department.
The uniquely versatile services of the system include the display of the assemblywise distribution of every important reactor parameter (e.g. outlet temperature, heatup, 2D and 3D flux and power, peaking factors, burnup, etc.) in the form of (numerical as well as various colour coded)
core maps , axial distribution of the flux, power or linear heat rate along selected assemblies, values of the most important parameters, control rod positions , SPND readings, event lists trends of selected parameters, various logs, hardcopies etc. A transient planning and strategy verification procedure is also available in the system.
Colour coded core map of the functioning thermocouples and axial linear power distributions
Various recorded data sets (archives) make a posteriory data processing and event recovery easy and also offer the possibility of archives replay parallel to the on-line functioning of the system.
The system is functional uninterrupted at all four units of the Paks NPP so far having served about 18 reactor years with virtually 100% availability. Besides its classical operator assisting function it proved to be a very effective tool of the NPP safety and control management.
