POWER May 2022 Intl - 16

CONNECTED PLANT
Small Modular Reactors Provide
Opportunity to Rethink
Automation for Nuclear Generation
An emerging generation of small modular reactors is encouraging suppliers and
regulators alike to consider new digital instrumentation and control approaches.
Paul Miller
W
hile instrumentation and control
(I&C) technology represents a
relatively small percentage of
the overall capital investment for any
nuclear power station, it often plays an
outsized role for safe, reliable, and efficient
operation. Recognizing the potential
benefits, the U.S. Nuclear Regulatory
Commission (NRC) and other regulatory
agencies have become more open to digital
I&C technology in nuclear facilities.
The new wave of small modular reactors
(SMRs) currently in development are
particularly ripe for new digital technology
solutions. SMRs offer cost, siting,
and safety benefits relative to full-scale
nuclear generating plants, but will lack
comparable economies of scale. This is
particularly true when it comes to staffing
for operations and maintenance (O&M)
functions. And while SMRs are designed
to reduce the need for human intervention
should something go wrong, ample
opportunities remain for new digitally
enabled automation technologies to improve
SMR performance, reduce O&M
costs, and further improve overall safety.
Guy Anderson, Chief Nuclear Officer
of Moltex Energy, which is developing
Canada's 300 MWe Stable Salt ReactorWasteburner
(SSR-W) SMR, stressed that
wherever possible, the company's approach
is to utilize the inherent design
characteristics to provide most control and
safety functionality. He believes that while
instrumentation will still be needed, it will
be used mainly to support monitoring and
display functionality for the operators.
According to GE Hitachi's Jon Allen, the
company's BWRX-300 SMR " places limited
demands on the operator compared to
the existing LWR [light water reactor] fleet
because it is a natural circulation BWR
[boiling water reactor] with passive safety
systems that provide at least seven days
of coping time without operation actions. "
Diane Hughes, NuScale Power's vice
president of Marketing and Commu16
nications
commented that " the NuScale
Power Module design is very safe
and simple to operate with no operator
actions or complicated automated sequences
needed for safety. "
Holtec's SMR-160 is also designed to
minimize the load on operators should
an accident scenario arise. The reactor
is passively cooled for design basis shut
down. The reactor coolant system continues
to circulate by thermo-siphon action
during accident scenarios.
Bayen Rafeh from the I&C group at
nuclear services and technology supplier,
Framatome, agreed that less human intervention
will be required in the normal
operation of SMRs and that the simplification
and integration of components and
architecture also means that fewer functions
will have to be implemented, reducing
the need for automation equipment.
SMR Automation Trends
Due to the inherently simplified nature
of SMRs, suppliers envision that new automation
and information technologies
will be leveraged not so much to reduce
the basic process control burden on operators
as to provide supervisory control
functionality to enhance situational
awareness and support multi-module
planning and dispatch functions.
According to Patrick Essner, team
leader for Holtec's electrical and I&C
group, " Multiple plant loads create new
challenges for operators. There definitely
are opportunities to use new technology.
Holtec will use the latest available
technology that has been approved for
nuclear service. "
The I&C and human-machine interface
(HMI) for GE Hitachi's BWRX-300 will
be evolutions of the company's recent
designs. According to Allen, " Current
protection, control, and monitoring with
their associated HMI design approaches
will be used following proven guidelines
and practices. HMI optimization ensures
that the operations staff can be lean. "
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Centralized Control Rooms for
Multiple Reactor Modules
To facilitate reduced operations staff and
enable fewer operators to simultaneously
monitor and control multiple small
modular reactors within a common SMR
facility, most will have central control
rooms (Figure 1).
Hughes at NuScale Power, which is
developing the 77 MWe NuScale Power
Module, commented, " Most nuclear
plants in the U.S. consist of a single- or
dual-reactor arrangement and regulations
currently limit the number of reactors that
can be controlled from a single control
room to two and have limited digital control.
SMR control rooms will likely be fully
digital and change the paradigm of operation
that exists in current analog nuclear
power plant control rooms. ... NuScale
developed the information needed to
obtain NRC approval that allows up to 12
NuScale Power Modules to be operated
from a single control room. "
According to Essner at Holtec, " Our
overall goal is to make the system simple
and safe to operate. " To this end, there
will be a single operator interface across
the plant. Overall control philosophy is
to centralize the control room to simplify
operation and make the operators more
efficient. The safety and non-safety systems
are separate but can communicate
with each other to simplify operation.
" The control system basically is a centralized
controller and control room with
remote I/O [input-output] cabinets. " He
added that the relatively small size of the
plant means the cabling requirements
are much simpler than in a full-scale nuclear
plant.
Framatome envisions that multi-module
SMR plants can share a main control
room but will require extensive human
factors engineering and simulation in the
early stages of design.
Factory-Installed Instrumentation
Since the SMR concept calls for reactor
POWER | May 2022
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POWER May 2022 Intl

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