Overall Instrumentation and Control Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 276

erative heaters of high pressure and in the form
of steam returns to the condenser through steam
lines, steam collector and turbine set. Coolant loss
in the secondary circuit is compensated by supply
of chemically purified water into the condenser.

First stage of modernization (1993-2000) was
characterized by using the systems designed by
foreign companies USA (Westinghouse), Czech
Republic (Skoda), Russia (Kurchatov Institute),
France (SYSECA), etc. Most of these systems
were safety-related.
Ukraine had no uniform strategy for I&C
modernization at that time. Some of these systems
had good fate and continue to operate now. This
concerns first of Safety parameters display system
(SPDS) for 11 Ukrainian units which operated at
that time. SPDS was designed by Westinghouse
(USA) together with joint USA - Ukrainian Cor-
poration “Westron” (see Chapter 1).
Some of these systems (e.g. computer informa-
tion systems designed by SYZECA were replaced
during the second stage of modernization.
Ukraine did not have its own regulations related
to I&C systems during that time. The Ukrainian
Regulatory Authority used USSR standards and
standards of the countries-designers in licensing
process for these systems (Brenman, 2006).
Second stage of modernization was imple-
mented during 2001-2011. The main peculiarities
of this stage are:

PRINCIPLES I&C SYSTEMS
MODERNIZATION AT
NPPS IN UKRAINE

The reasons for upgrading of I&C systems at NPPs
in Ukraine are as following:

• The incomplete compliance with the mod-

ern requirements on nuclear and radiation
safety.

• The end of the useful life of the most types

of the instruments (lifetime of many instru-
ments is now over or close to the end (8-10
years).

• The absence of spare parts for many types

of equipment because a lot of manufactures
that supplied NPPs with spare parts before,
ended their actions or changed direction of
their work after USSR disintegration.

• Modern computer techniques were widely
used.
• New national regulatory framework was
developed.
• Most I&C systems were designed and pro-
duced by Ukrainian companies.
• Modernized I&C were not only safety-
related systems but safety systems as well
(e.g., reactor protection systems).

Let us consider the first reason in detail. This
reason includes:

• Low level of reliability.
• Low quality of man-machine interface.
• Non-satisfactory diagnostics of hardware
and software.
• Discrepancy to seismic requirements, to
requirements of resistance to actions of
environment.
• Low ire resistance.
• Absence of systems for information per-
sonnel support.
• Absence of high (general plant) level co-
operated with unit level.

The modernization strategy is analyzed in the
following aspects:

• Strategy of operators (NPP or National

Nuclear Energy Generating Company
«Energoatom»).

• Strategy of I&C systems designers.