General Provisions - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 12

equipment. Peripheral equipment is a com-
plex of devices that are operated indepen-
dently from each other and can be located
at a distance from central equipment.

and / or electrically interconnected). Operation
conditions of the peripheral device (operating and
limiting parameters of environment, mechanical
effects possible in the process of operation and
abnormal natural phenomena, severity grade of
the electromagnetic environment in the supposed
location, etc.) are design specific which allows
defining the safety class, seismic category, group
operating conditions and accommodation of each
peripheral devices and regulating requirements for
it, resulting from this classification.
Peripheral devices of modern individual I&C
can be divided into:

Moreover, I&C system includes: interface
cables; service equipment used in the process of
programming, debugging, checking, maintenance
on the operating site; internal power supplies;
software and operating documentation.

Peripheral Equipment

Peripheral equipment (peripheral or field devices)
can be divided on three groups: • One-of items , designed and supplied to

NPPs as components of speciic I&C sys-
tems important to safety. • Measurement ield devices (sensors), in-

tended for obtaining data on state and /
or operation of technological systems and
equipment.
• Actuating ield devices (actuators), directly
inluencing starting or regulating elements
of technological equipment.

• Replicated products , specially designed as

components of not previously determined
set of I&C systems important to safety and
allowed for use at NPPs.

• Commercial of the shelf products of gen-

eral application, available on the market,
the design and manufacturing of which do
not intend to use I&C systems important
to safety, as components. In English litera-
ture, for examples, IAEA, 1999, such items
are indicated by abbreviation COTS.

• Elements of manual input, display, alarm

(HMI devices), used for visual and audible
alarm for operating personnel, input of
manual control commands, etc.

Sometimes the impulse lines from the piping
or technological equipment to main and blowing
valves of pressure sensors, differential pressure
and level sensors (together with condensation and
leveling vessels and other valves related to these
lines) are also related to peripheral devices.
Measurement field devices include tempera-
ture, level, flow sensors, pressure and differential
pressure measurements, neutron flux measure-
ments, measuring transmitters, etc.
Actuating field devices include motor-, sole-
noid- and air-operated valves, valve control motors,
switchgears, motor control centers, etc.
A peripheral device is usually designed as
one independently operated device (rarely - as a
group of independently operated parts, structurally

Application of COTS in the structure of I&C
systems important to safety is one of the current
trends caused by the mass effect of their produc-
tion and heavy competition of global leaders in
information technology field, as a result there is
a significant improvement of application prop-
erties (accuracy, speed, noise immunity, etc.),
relatively low cost, sufficient reliability, approved
in different fields of application, independence
from one manufacturer, high quality of company
maintenance.
At the same time it should be considered that
COTS are designed and manufactured without
taking into account international and national
regulations, rules and standards on nuclear safety