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NuclearPlantJournal.com Nuclear Plant Journal, January-February 2016
FPGA-based controller board SBC-01
emulated the functions of Intel 8085
microprocessor correctly. The successful
case provides valuable reference and
know-how for a greater scope of digital
upgrade in years to come for the industry
to resolve the obsolete problem.
Summary and
Discussions
The FPGA implementation at
YGN Unit 3&4 was very successful,
within budget and schedule. The
intended objective and safety functional
requirementswere fullymet.The upgraded
system has been running for more than
5 years now, which shall be used as an
excellent example for the nuclear industry
to follow. The upgrade process complied
with the US NRC and South Korean KINS
(Korean Institute of Nuclear Research)
regulatory requirements.
As lessons-learned, it is important
that the FPGA design and implementation
follow acceptable lifecycle process
(e.g., one as defined in IEEE Std 1074-
1995) and rigorous V&V process as
defined in IEEE Std 1012-2012, as
well as fundamental safety I&C design
principles such as simplicity, single-
failure tolerance, determinism, and fail-
safe. System design requirements such
as redundancy, diversity and defense in
depth has to be considered and built into
design in coordination with the plant
stakeholder’s requirements and reference
to the regulatory guidance.
It is equally important that the
industry's best engineering practice and
digital I&C know-how experience were
applied to produce effective managerial
and efficient implementation outcome.
The successful implementation of
FPGA replacing the obsolete Intel 8085
microprocessors in which FPGA emulates
the process of the microprocessors and
interprets the execution of CPU processes,
when coupled with knowledge base of
HFC-6000 platform, which has been
extensively reviewed by the US NRC and
has obtained its Safety Evaluation Report
(SER) from the US NRC in April 2011,
provides valuable experience and know-
how for a greater scope of digital upgrade in
operating power plants. The FPGA digital
upgrade on existing NPPs is technically
feasible and economically attractive.
One such future upgrade will include
a replacement of all existing I/O boards
(both analog and digital), and controller
boards, which are Intel 188EB and/or
386EB based microprocessors, with the
latest FPGA based technology. With the
upgrade using the latest FPGA based
I/O and controller boards, the addition
of HFC-6000 rack will enhance the
communication master capability to 100
Mb/sec (from the existing ICB’s (inter
communication bus) 10 Mb/sec). This
will greatly increase the capability for
status and diagnostic information passing
between remotes.
Shown in the Figure is an exemplary
illustration for a greater digital upgrade
scope using FPGAs to replace existing
I/Os, single loop controllers, and loop
masters. In this configuration, the FPGA
based single loop controller performs its
dedicated loop control functions on its
own, independent of other loops. The
controller can also communicate with a
remote, through which status information
can be passed to another loop or vice versa
via asynchronous message passing. When
single loop controller communicates in
this fashion, one loop controller failure
will not cause failures of other loop
controllers or the entire system.
When an FPGA based single loop
controller communicates with a remote,
a communication protocol called
F-Link (FPGA Communication Link) is
implemented via a safety redundant RS-
485 serial communication port. The loop
status information is passed from one
remote to another. The communication
between remotes is implemented via a
proprietary protocol of deterministic pass
token Ethernet through Communication
Link (C-Link), which is a super highway
of communications of the HFC-6000
system. Engineering workstations can
be connected to the CL (communication
Link) via a secure gateway as a safe
firewall in such a configuration.
On theother hand,with the experience
in FPGA applications and knowledge
base of HFC-6000 platform, the FPGA
based controller platform development
has become mature. The FPGA based
platform will utilize HFC-6000 existing
I/O boards, communication modules, and
enhanced safety I/O modules. The new
FPGA based platform will enhance HFC-
6000 product line diversity, and become
part of the qualified HFC-6000 family.
Either in digital upgrade, which
solves the industry pressing obsolete
issue, or in developing a new platform for
use in new nuclear power plants, FPGAs
will be used greatly in many years to
come.
Acknowledgements
We would like to express our
gratitude to Xu Huang, William Luo, and
Huaisong Xu for beneficial discussions.
Note
: A detailed version of the paper
is available from the listed contact.
Contact: John Stevens, Doosan HF
Controls Corp., telephone: (469) 203-1381,
email:
.
FPGA Safety...
