 |
|
|
| RESIMIC |
| Taurus has designed, developed,
tested, manufactured and installed a unique product for the Westinghouse Bettis Atomic
Power Laboratory 1990, and has recently completed an upgrade of the previous
implementation. To the best of our knowledge, this unique product is not available
anywhere else in the world. The new product is called a Reactor Simulator for
Nuclear Instrumentation and Control Testing in Real-time (RESIMIC). It is a
custom designed product that enables a nuclear I & C system of reactor instrumentation
panels and instruments to be connected directly to it instead of connection to the actual
nuclear reactor system. This allows the nuclear I&C system to be tested in a dynamic
real-time environment without connection to the actual reactor. The advantages of this
reactor simulator is that it not only frees the reactor from this role, but it also allows
a much wider range of test scenarios and reactor malfunctions to be developed and tested. |
| Product
Description |
| The major elements of RESIMIC are as
follows: |
- Simulation computer system with real-time model of
reactor core dynamics
- Engineering Control Station (ECS) with color CRTs and
keyboard and special purpose function panels
- High-speed real-time I/O system
- Digital in-core detector emulation hardware
|
| Simulation
System |
| A SUN computer system workstation with
multiprocessors is used to implement a real-time dynamic model of the reactor core. The
SunOS Unix operating system with real-time extensions is employed in order to guarantee
transportability to other Unix platforms such as Silicon Graphics or Hewlett Packard. |
| Taurus-designed models have been used
on several PWR projects and, therefore, have been proven to meet the requirements of ANS
3.5. The RESIMIC system enables the customer to use his own, or RELAP5 PWR, model. The
customer's own core model can be used but must be written in FORTRAN or C under the Unix
5.0 operating system. The model must then be mapped to match the I/O system calls on the
high-speed VMEBUS with shared memory. |
| Taurus Modeling Technologies |
| Taurus’ simulator software
(described in other documents) is designed so that the simulator response is the same as
the reference plant in real-time. This requires the extent of simulation be complete, and
the rate of software processing be fast enough to ensure that meter and recorder response
be smooth; also that abnormal control delays are not noticeable to the operator. With the
scope of simulation provided by Taurus, those responses an operator would expect in the
plant will be seen on the simulator. Responses such as shrink and swell of the steam
generator level, electrical motor starting current surges, etc., may not be specifically
quantified in the data for the reference plant but occur on all power plants, and will in
turn be simulated. |
| Mathematical models are derived by
applying the laws of physics to each plant component. The results are contained in a set
of differential algebraic, and Boolean equations that are solved by the digital computer
in a sequential process. Inherent in this approach is the phenomenological basis of system
simulation such that the equation set accommodates the wide range of system operations
rather than merely a finite interval around predetermined design operating points. |
| The plant systems simulation software
will be subdivided into separate models representing separate physical phenomena and plant
components. Each plant system is mathematically represented by one model which spans all
plant operating states from PRE-STARTUP CHECK through onset of boiling, pressurization,
plant heat up, turbine loading, power range maneuvering, and back down to COLD SHUTDOWN
conditions. This elegantly simple approach avoids discontinuities when switching between
models. By the use of conservation laws (charge, energy, mass, and momentum) and the
phenomenological laws (concerning heat transfer, hydrodynamics, Ohm’s law, etc.) no
analog signal generation is needed (or desired). |
| Best Estimate Code |
| Taurus, in cooperation with Science
Applications International Corporation (SAIC) offers licensing grade models as an option
for use on the RESIMIC system. The complexity of RELAP5 requires evaluation of each
customer’s specific applicability. |
| The Light Water Reactor (LWR)
transient analysis code, RELAP5, was developed at the Idaho National Engineering
Laboratory (INEL) for the U.S. Nuclear Regulatory Commission (NRC). Uses of this code
include: |
- Analyses Required to Support Rulemaking
- Licensing Audit Calculations
- Evaluation of Accident Mitigation Strategies
- Evaluation of Operator Guidelines
- Experiment Planning and Analysis
|
| RELAP5 has also been used as the basis
for a nuclear plant analyzer. Specific applications of this capability have included
simulations of transients in LWR systems that lead to severe accidents, such as loss of
coolant, Anticipated Transients Without Scram (ATWS), and operational transients such as
loss of feedwater, loss of offsite power, station blackout, and turbine trip. RELAP5 is a
highly generic code that, in addition to calculating the behavior of a reactor coolant
system during a transient, can be used for simulation of a wide variety of hydraulic and
thermal transients in both nuclear and non-nuclear systems involving steam water
noncondensible solute fluid mixtures. |
| The RELAP5 code is based on a
non-homogeneous and non-equilibrium model for the two-phase system that is solved by a
fast, partially implicit numerical scheme to permit economical calculation of system
transients. The objective of the RELAP5 development effort from the outset was to produce
a code that includes important first-order effects necessary for accurate prediction of
system transients. But it is sufficiently simple and cost-effective, allowing parametric
or sensitivity studies. |
| The code includes many generic
component models from which general systems can be simulated. The component models
include: |
- Pumps
- Valves
- Pipes
- Heat Structures
- Reactor Point Kinetics
- Electric Heaters
- Jet Pumps
- Turbines
- Separators
- Accumulators
- Control System Components
|
| In addition, special process models
are included for effects such as: |
- Form Loss
- Flow at an Abrupt Area Change
- Branching
- Choke Flow
- Boron Tracking
- Noncondensible Gas Transport
|
| The system mathematical models are
coupled into an efficient code structure. The code includes extensive input checking
capability to help the user discover input errors and inconsistencies. Also included are: |
- Free Format Input
- Internal Plot Capability
- Restart
- Renodalization
- Variable Output Edit Features
|
| These user conveniences were developed
in recognition that generally the major costs associated with the use of system transient
code is in the engineering labor and time involved in accumulating system data and
developing systems models. The computer costs associated with generation of the final
result is usually small. |
| The development of the models and
codes that constitute RELAP5 has spanned approximately 12 years from the early stages of
RELAP5 numerical scheme development to the present. RELAP5 represents the aggregate
accumulation of experience in modeling core behavior during severe accidents, two-phase
flow processes, and LWR systems. The code development has benefited from extensive
application and comparison to data in the LOFT, PBF, Semiscale, ACRR, NRU, and other
experimental programs. |
| Engineering Control Station |
| The ECS (described in detail in other
documents) provides a user window into the reactor simulation and I&C equipment. It is
driven by a dedicated SunOS Unix workstation and color monitors with a single keyboard and
mouse. |
| A function panel with backlighted
pushbuttons can also be provided to provide instructor or tester controls for the
simulator, I&C testing and malfunction selection. However, a graphics-oriented
X-Windows terminal can be provided in its place as an option. |
| High Speed Real-Time I/O System |
| A specially designed high-speed
real-time I/O system has been developed for RESIMIC. This is an intelligent
microprocessor-controlled I/O System on a VMEBUS with shared memory that shares the
simulation database with the simulation computer system. The I/O System has a thruput rate
of 100 updates per second for 5000 channels of digital and analog I/O. |
| Detector Emulator Hardware |
| The in-core detector emulator hardware
is the heart of the RESIMIC system as it was uniquely designed to faithfully emulate all
the dynamics of the in-core detectors and other nuclear instrumentation. It is unique
because it provides a realistic representation of the dynamics as well as the low-current
detector responses than would be possible using a modeling approach to the detectors.
Hardware emulation of the in-core detectors was chosen by the customer (Westinghouse
Bettis Atomic Power Laboratory) because this emulation is the most critical factor that
affects the accuracy of instrumentation and control of the reactor system. Improper or
inaccurate detector simulation could result in inaccurate data acquisition and consequent
false control actions by the I&C system. As a result of this critical control factor,
it was decided that only a specially designed hardware emulation of the in-core detectors
would accomplish the objective. |
| The six detector emulator cards
available are as follows: |
- Resistance Temperature Detector (RTD) Emulator
- Linear Variable Differential Transformer (LVDT)
Detector Emulator
- Intermediate Power Range (IPR) Nuclear Instrument
Emulator
- Pump Speed Sensor (PSS) Emulator
- Individual Rod Position (IRP) Detector Emulator
- Source Range (SR) Nuclear Instrument Detector
Emulator
|
| Applications and Benefits of RESIMIC |
| Applications |
| The unique design features of RESIMIC
are such that the product can be used for a multitude of different applications with
meaningful advantages and benefits for the user. |
| For example, the product can be
configured to: |
- Meet the exact design requirements of the customer
and the I&C manufacturer
- Configured with any number of digital and analog I/O
channels to match the nuclear I&C system to be tested
- Provided with any number of reactor and nuclear
instrumentation failures and malfunctions
- Provided with high-resolution X-Terminal color
monitor graphics depicting simulation diagrams, plant schematics, control and logic
diagrams and malfunction activation menus. Soft-panels emulation with active controls can
also be provided to emulate the real I&C panels and instruments.
- Customer-supplied reactor core models can be adapted
to run on the RESIMIC system. These must be supplied to Taurus Technologies in advance of
shipment to allow integration into the system.
|
| Benefits |
- RESIMIC can be used both as a real-time nuclear
I&C testing system as well as a reactor operator trainer. Since both of the I&C
system panels and a real-time reactor simulation are active, the functionality of RESIMIC
is such that full reactor operations can be exercised in real-time.
- RESIMIC allows a complete and faithful testing
environment of any nuclear I&C system design. The fact that the actual reactor in not
in the loop allows the simulator to test for many more operating and accident scenarios
including fast reactor transients, control-rod maneuvers, dropping of selected control
rods, xenon oscillations, LaSalle oscillations, LOCA accidents, ATWS, etc.
- RESIMIC can be used not only to fully test the
nuclear I&C system under abnormal reactor operating conditions, but can also be used
to fine-tune the control algorithms or the control system configuration and design.
- RESIMIC enables a much safer environment for the
testing of I&C systems, for the training of reactor operator crews, or for retraining
of SROs (Senior Reactor Operators).
- The system also allows a much larger range of test
conditions including out-of-range tests, severe accident testing and reactor malfunctions
that cannot be duplicated in the actual reactor.
- RESIMIC is also an ideal tool for the development and
testing of reactor operating procedures, and the development of on-line expert systems for
the operating procedures. For example, non-essential reactor scram prediction and
avoidance can be tested and implemented in the I&C system.
|
|
