General Provisions - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 21

processes from sensors and transmitters; performs
linearization, scaling and transformation of analog
signals into digital form; storage and processing of
digital data; generation of control, protection and
interlocking signals; transfer of information to an
upper hierarchical level. Diagnostics, automatic
restart, configuration possibility, off- and on-line
control and readjustment are also provided.
Devices (sub-complexes) of upper level are
implemented on the platform of workstations
manufactured by Sun Microsystems, Inc. with a
real time operation system Solaris. Workstation
contains processor, random access memory, disc
memory, controllers of Ethernet dataway, sequen-
tial and parallel ports. Depending on subcomplex
purpose, it can contain one or two video monitors
with relevant graphics controllers (video cards),
alphanumeric and / or function keyboard, ma-
nipulator, ink and laser printers, acoustic system.
Subcomplexes of upper level archive, display,
record data, prepare and output messages for
NPP computer information system. For complex
computations, which require high operating speed,
a significant capacity of random access memory
and on-line database access, industrial personnel
computer is included into the proper subcomplex.
All operating stand-alone devices of lower and
upper level are connected by a common redun-
dant 32-bit digital network Westnet-ΙΙ Plus Data
Highway with trunk line topology, deterministic
access to communication environment and com-
munications protocols. Such a solution provides
simple implementation of distributed database, but
requires expensive hardware and imposes limita-
tion on a total number of controlled parameters.
Both trunks of Westnet-ΙΙ Plus network operates
simultaneously; when one of them fails, the
system keeps operability without degradation of
characteristics. Via local Ethernet network serv-
ers of upper level can transfer and obtain such
information, for which possible communication
delay (program load, transfer of archival data,
printout) is not critical.

In Ukraine on the basis of WDPF-II mod-
ernization of information systems of units 1 and
2 South-Ukrainian NPP, upper level of in-core
reactor monitoring system of unit 2 Zaporozhe
NPP, regulators of feed water level in steam
generators of units 1 and 3 South-Ukrainian NPP
was performed. Systems, providing parameters of
vibration monitoring of main circulating pumps in
unit 3 Rovno NPP and safety parameters display
systems at all Ukrainian units were designed and
introduce into operation.
OVATION — platform of Westinghouse Elec-
tric Company, that replaced WDPF-ΙΙ. Instead of
original network Westnet-ΙΙ Plus it uses token-ring
network with a standard interface FDDI (Fiber
Distributed Data Interface). Fiber-optic cable with
two optical fibers is recommended as a physical
communication environment. One of it forms a
main ring, and it is used for circulation of marker
and data. The second fiber forms a standby ring,
and in normal mode it is used for control of com-
munication via the main ring. In case of failure
(break) of any segment of the main ring, stations,
being on both sides of break, will automatically
reconfigure path of marker and data circulation,
connecting standby ring. Also FDDI standard
regulates other features, providing network fault
tolerance. Protocol's determinacy (possibility to
predetermine maximum delay of package trans-
mission via network) is especially important for
control systems critical to information transfer
period.
In stations of lower level controller is imple-
mented on the basis of processor architecture
IA-32, dominating on personnel commuter market
in the period of OVATION development. Real
time operation system supports multitask mode
and operation with task priorities. For reliability
improvement controllers can be duplicated, where
the main controller operates in control mode and,
moreover, checks operability of the duplicating
controller and network; at the same time the du-
plicating controller checks operability of main