NPP: Power Grid Mutual Safety Assessment - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 398

generating system, high voltage transmission
system, lower voltage distribution system and
other support facilities.
Three types of generation facilities are oper-
ated in Ukraine, including thermal power plants
(steam turbine and diesel types), hydroelectric
plants (hydroelectric proper and hydroelectric
accumulating plants) and NPPs. Thermal power
plants account for about 50% of the electric power
produced in Ukraine. Most of these thermal power
plants (TPPs) are old, with antiquated equipment,
obsolete technology, and largely lacking modern
pollution control equipment. Only about 10% of
Ukraine's TPPs had undergone any significant
reconstruction.
The major fuel for the plants is natural gas
(76-80%), but they also use black oil (15-18%),
and coal (5-6%). Most steam power plants have
outdated equipment, which does not correspond
to present-day environmental requirements, and
calls out for reconstruction, upgrade, or complete
replacement.
Ukraine's four nuclear power stations operate
15 reactors with a capacity of 13,8 Giga watts
(GW), or nearly one-quarter of the country's to-
tal. They generate around 88,8 GW of energy, or
over 47.9% of the country's power output, with
the construction of two reactors with a capacity
totaling 2 gigawatts (GW) in its final stages. Power
reactors have operated in Ukraine since 1977, and
over 300 reactor years of operating experience
have been accumulated.
Power resources of Ukraine are mainly formed
by domestic generation capacities (nearly 98%),
with the import share being insignificant (2%).
The power is largely consumed inside the country
(97%), with a small part exported (3%). In the
future, the need for power is expected to grow
calling for intensification of the sector develop-
ment and optimizing of the organization structure
and economic mechanisms of functioning in the
market environment.

Ukraine's electric networks are numbered
nearly 22, 7 thousand km., 4,9 thousand km. of
them are under voltage 400-750 kW (high voltage
transmission lines), 13,2 thousand km. - under
330 kW, 4,6 thousand km. 220-110 kW (lower
distribution lines). Their conditions are getting
more aggravated every year. 34% of overhead
transmission lines (220-330 kW) have been operat-
ing nearly 40 years. Approximately 52% of them
have to be renovated, 76% of transformer substa-
tions have reached the end of their service life.

BACKGROUND

All facts mentioned above are given to show the
high complexity of Ukrainian energy sector and
problem of its reliability assurance. Reliable op-
eration of the NPP implies that PG, to which it is
connected, is reliable. Disturbances in PG opera-
tion can originate from natural disasters, failures,
human factors, terrorism, and so on.
If PG and NPP are considered together as SoS,
we can conclude that PG reliability and safety are
stipulated by the NPP safety. Outages and faults
will cause serious problems and failures in the
interconnected power systems. It means that unsafe
power grid and NPP could be considered mutual
risk factors undermining the safety of both facili-
ties. In order to provide stable and safe operation
of NPPs, a systematic way of formalization and
evaluating these influences is needed.
The object of the chapter - is to introduce
approaches and techniques, which allow to evalu-
ate the mutual influences between NPP and PG,
understand the dynamic risks nature caused by
their interactions.
The techniques represented in the chapter can
be considered an essential part of PG risk manage-
ment and can serve as a base for decision-making
to avoid disturbances or minimize the severity of
their consequences considering the interaction
between NPP and PG systems. These techniques