Areva EPR

■ EPR NUCLEAR ISLAND
INSTRUMENTATION & CONTROL SYSTEM
A nuclear power plant, like any other industrial facility, needs technical means to monitor and control its
processes and equipment. These means, as a whole, constitute the plant Instrumentation & Control (I & C)
processes, which actually comprises several systems and their electrical and electronic equipment.
Basically, the I & C system is composed of sensors to transform
physical data into electrical signals, programmable controllers
to process these signals and control actuators, monitoring and
control means at the disposal of the operators.
The overall design of the I & C system and associated equipment
has to comply with requirements imposed by the process, nuclear
safety and operating conditions.
To design the EPR and its I & C system, specific attention has been
given to ensure a high level of operational flexibility in order to fit with
electricity companies’ needs. As a result, the EPR is particularly well
adapted to load follow and remote control operation modes.
† A plant I & C system, completely
computerized, supported by
the most modern digital technologies,
for high-level operational flexibility
EPR I & C OVERALL ARCHITECTURE
Inside the overall I & C architecture, each system is characterized
depending on its functions (measurement, actuation, automation,
man-machine interface) and its role in safety or operation of the plant.
A several level structure
Consideration of the different roles played by the different I & C
systems leads to a several level structure for I & C architecture:
• level 0: process interface,
• level 1: system automation,
• level 2: process supervision and control.
(A level 3 deals with site management functions).
Different general requirements are assigned to each level.
The “process interface” (level 0) comprises the sensors, and the
switchgears.
The “system automation” level (level 1) encompasses I & C systems
to perform:
•reactor protection,
• reactor control, surveillance and limitation functions,
•safety automation,
• process automation.
The “process supervision and control” (level 2) consists of:
• the workstations and panels located in the Main Control Room,
the Remote Shutdown Station and the Technical Support Centre,
which are also called the Man-Machine Interface (MMI),
• the I & C systems which act as link between the MMI and the
“system automation” level.
Safety classification
I&C functions and equipment are categorized into classes in
accordance with their importance to safety. Depending on their
safety class, I & C functions must be implemented using equipment
having the appropriate quality level.
Redundancy, division, diversity and reliability
I&C systems and equipment of the EPR comply with the principles
of redundancy, division and diversity enforced for designing EPR
safety-related systems. As an illustration, the Safety Injection System
and the Emergency Feedwater System, which consist of four
redundant and independent trains, have four redundant and
independent I & C channels.
Each safety-related I & C system is designed to satisfactorily fulfil its
functions even if one of its channels is not available due to a failure
and if, at the same time, another of its channels is not available for
preventive maintenance reasons or due to an internal hazard (e.g.
fire).
I&C systems and equipment participating in safety functions are
specified with a level of availability in compliance with the safety
probabilistic targets adopted to design the EPR.
† A quadruple redundant safety-related I & C
for a further increased level of safety.
Description of the I & C architecture
Functional
safety class
Equipment
quality level
F1A Functions required in case of accident E1A
to bring the reactor to controlled state.
F1B Functions required after an accident to bring E1B
the reactor to safe state.
Functions intended to avoid the risk
of radioactive releases.
F2 Other functions contributing to plant safety E2
(adherence to limit operating conditions,
surveillance of safety system availability,
protection against the effects of internallygenerated
hazards, detection/monitoring
of radioactive releases, functions used
in post-accident operation…).
NC Non-classified functions. NC
I&C technology
Concerning I & C technology, Framatome ANP uses a consistent
I&C system based on its TELEPERM-XS technology for safety
applications and on a diversified technology for standard applications.
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