Page 12 - Dynamics and Control of Nuclear Reactors

1.2 System dynamics and control design 3

The ability to describe the system dynamics using a variety of models is crucial to
achieve a good engineering design. The control or regulation of a power plant
requires critical measurements of process parameters (and neutron power measure-
ments in a nuclear power plant). As a result, a typical large nuclear plant employs a
few thousand measurements. These are used by control systems, plant safety (pro-
tection) systems, and by monitoring systems. Thus, instrumentation and control play
a critical role in safe and reliable operation of commercial nuclear power plants.
Dynamic performance is an important issue in many industrial systems. The key
issues in dynamic system performance are the following:
• Can the system be moved from one desired value (set point) to another in an
acceptable manner? That is, without deviating from limits of variation and
within an acceptable time interval.
• Can the system respond in a stable manner without exceeding safety limits when
subjected to unplanned disturbances (possibly due to an accident, an external
disturbance, failure of a component, or human error)?

The latest development to enhance the power and usefulness of digital simulation is
modular modeling software. Modular modeling software provides a menu of models
of commonly encountered systems (reactor kinetics, fuel-to-coolant heat transfer,
hot and cold leg volumes, steam generators, feed water heaters, pressurizers, steam
turbine, condenser, moisture separators, steam reheaters, pumps, valves, etc., includ-
ing their control modules) and an automated means for linking them together and
running simulations. Because the model for each component is used in many differ-
ent analyses, great effort by highly qualified experts to develop and check the soft-
ware is warranted.
Several vendors market new simulation and control design software systems. The
International Atomic Energy Agency (IAEA) also provides simulators for most types
of power reactors to qualified organizations in member countries. These are used
quite extensively for training in industry and universities. Ref. [1] provides the
procedure for requesting IAEA simulation software. Recommendation by the IAEA
representative for the country of the requester is required.
In this book, we emphasize the use of the software system MATLAB and its
Toolboxes. A companion system called Simulink is used for the simulation of large
processes, such as a nuclear power plant. These software systems are designed for
implementation in personal computers (PCs) and (larger) mainframe computers.
The MATLAB, Simulink, and the toolboxes are comprehensive collections of func-
tions (software modules) and are developed and marketed by The MathWorks, Inc.
We recommend strongly that the students familiarize themselves with MATLAB,
Simulink and the associated Toolboxes [2, 3]. ‘MATLAB is a high-performance
language for technical computing. It integrates computation, visualization, and pro-
gramming in an easy-to-use environment. The name, MATLAB, stands for matrix
laboratory’ [4]. An open source simulation platform based on the Modelica model-
ing language is a popular resource for system modeling and simulation [5].