Overall Instrumentation and Control Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 277

• The main features peculiar to the strategy

of operators are the following:

modiied to include new functions,
e.g. control of primary-to-secondary
leakage accidents.
◦ Modernizations can be related to the
central part of a system or to a sys-
tem as a whole, together with sen-
sors, cables, actuators. In the begin-
ning of this stage modernizations
involved only central-part of systems.
(as a rule, computer-based). In re-
cent times, replacement of cables and
sensors is included into the scope of
modernizations.
◦ Extensive I&C modernization took
place before unit life extension. NPP
paid special attention to these actions
and assigned resources for unit life
extension, including replacements
of old I&C systems. The Regulatory
Authority requested these replace-
ments from the NPP to receive a li-
cense for unit life extension. Some of
I&C systems, which were modern-
ized to obtain approval for unit life
extension, is shown in Table 1.

◦ Most modernizations take place dur-
ing shutdown for refueling. This time
is limited, and in some cabinets the
shutdown period is insuicient for
modernization. In these cabinets,
modernization is implemented in
2 or 3 stages (examples: complete
modernization of the unit computer
information system or neutron lux
monitoring system). The presence
of several stages required additional
activities to ensure the compatibility
between modernized and non-mod-
ernized parts of the systems.
◦ All I&C modernizations can be divid-
ed into pilot (modernizations imple-
mented for the irst time at NPP with
speciic reactor type) and replicated
(modernizations implemented before
at a speciic NPP type in Ukraine and
showed positive results). Of course,
use of replicated systems is prefer-
able in terms of safety justiication
and cost for acquisition of systems.
The scope of licensing actions for
replicated modernizations is substan-
tially smaller than for pilots. A spe-
ciic stage in the implementation of a
pilot system is its trial operation with
extensive support from the designer
and prompt feedback from the NPP
to the designer, involving analysis of
all failures, faults or NPP personnel
comments.
◦ Most modernizations used exist-
ing technological algorithms, which
were proven by long-term operation
of power units in Ukraine, Russia and
other countries. The algorithms were

The main features peculiar to the strategy of
designers are the following:

• Use of an aggregate of hardware, software
and service apparatus called hardware-
software complex (HSC) as the central part
of systems (see Chapter 1)
• Ukrainian Research and production
Corporation “Radiy” pioneered the appli-
cation of ield programmable gate array
(FPGA) for performance of safety func-
tions (reactor protection systems, engineer-
ing safety features actuation system, etc.).
Since 2004, more than 40 FPGA-based
systems have been installed at Ukrainian
NPPs. IAEA Independent Engineering