IEEE Power & Energy Magazine - March/April 2022 - 63

among different modules. Variations include operating all of
the units in a shared load-following configuration or assigning
some units to fixed-output operation and others as load-following
ones. Such differential operation may offer some inherent
advantages. Newly fueled units generally exhibit more responsive
characteristics in a load-following mode, than those near
the end of their fueling lifecycle due to their higher reactivity.
Thus, these units can be used for finer output adjustments.
Open Issues
Several open problems need to be investigated concerning the
integration of SMRs into renewable energy microgrids. Aspects
of these problems require interdisciplinary research that incorporates
nuclear, thermal-hydraulic, electrical power system
operation, and advanced instrumentation and control topics.
The Sizing Problem
Selecting the optimal size of one or more SMRs (and the corresponding
renewable sources and storage capacity within SMR/
renewable microgrids) relative to a given load scenario requires
significant research. An analysis must study short-term system
stability, long-term energy production, and the proportions of
the sources. Even though this type of analysis is well established
in the microgrid field for various nonnuclear resources,
these approaches need to be extended to include the operational
behavior and regulatory constraints of SMRs. Research
should also consider the lifetime performance of SMRs and
potential operating strategies for multi-unit SMRs. Examples
include combinations of fixed-output units and load-following
units. Also, strategies need to be developed for tiered deployment
strategies where different renewable energy resources and
SMR units are added or removed as the load demand changes.
The Interaction Problem
In applications of SMR/renewable microgrids in remote communities,
the relative sizes of the energy sources and the loads
to be supported are closer in proportion than those in traditional
power grids. The dynamic interactions among the primary energy
sources may need to be considered to deal with rapid changes in
load. Investigations must be carried out to understand the impact
of such coupling and to explore mitigation strategies. Advanced
control strategies for the power-electronic interfaced sources, traditional
synchronous generators, and energy storage systems are
needed to ensure that the entire microgrid operates stably, reliably,
and within power quality constraints. Systems that include
thermal loads form an integral part of the energy management
strategy. Control strategies for such loads, in concert with the
electrical generation system, also need to be developed.
The Autonomous Monitoring/
Control/Management Problem
Several of the proposed SMR designs are meant to be installed
and operated as essentially zero-maintenance, walk-away safe
units. In some cases, these can be buried underground and monitored/operated
remotely. Achieving this level of autonomy will
march/april 2022
require the development of high-reliability sensing and remote
monitoring technologies to initiate necessary remedial actions
if anomalies are detected. While the proposed SMR designs
include safety features that can shut the reactor down in the
event of a fault, the remainder of the microgrid should continue
to operate, though presumably at a reduced capability. Advanced
instrumentation and control approaches to support this autonomous
operation need to be developed and validated for multiple
operating scenarios within a microgrid environment.
Conclusions
SMRs with load-following capability can complement the intermittent
nature of renewable energy sources in a standalone microgrid
environment. Effective controls will allow these sources to be
integrated with moderate-sized energy storage to provide a highquality,
reliable, low-carbon supply of power. SMRs can be key
enablers for the widespread adoption of renewable energy-based
microgrids in off-grid applications. However, research is still
required to understand the intricate relationships among the
different energy resources and develop effective control strategies
for achieving safe and reliable operation with a high quality of
service under various load and environmental conditions.
For Further Reading
J. Buongiorno, M. Corradini, J. Parsons, and D. Petti, " Nuclear
energy in a carbon-constrained world: Big challenges and
big opportunities, " IEEE Power Energy Mag., vol. 17, no. 2,
pp. 69-77, Mar./Apr. 2019, doi: 10.1109/MPE.2018.2885250.
P. Sabharwall, S. Bragg-Sitton, L. Boldon, and S. Blumsack,
" Nuclear renewable energy integration: An economic
case study, " Electricity J., vol. 28, no. 8, pp. 85-95, Oct.
2015, doi: 10.1016/j.tej.2015.09.003.
D. Ingersoll, C. Colbert, Z. Houghton, R. Snuggerud, J. W.
Gaston, and M. Empey, " Can nuclear power and renewables
be friends? " in Proc. ICAPP, Nice, France, May 3-6, 2015,
Paper 15555.
" Advances in small modular reactor technology developments, "
International Atomic Energy Agency, Vienna,
Austria, Sep. 2018. [Online]. Available: https://aris.iaea.org/
Publications/SMR-Book_2018.pdf
M. F. Ruth, O. R. Zinaman, M. Antkowiak, R. D. Boardman,
R. S. Cherry, and M. D. Bazilian, " Nuclear-renewable
hybrid energy systems: Opportunities, interconnections, and
needs, " Energy Convers. Manag., vol. 78, pp. 684-694, Feb.
2014, doi: 10.1016/j.enconman.2013.11.030.
" A call to action: A Canadian roadmap for small modular
reactors, " Natural Resources Canada, Nov. 2018. [Online].
Available: https://smrroadmap.ca/
Biographies
Dennis Michaelson is with Western University, London,
N6A 5B9, Canada.
Jin Jiang is with Western University, London, N6A 5B9,
Canada.
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ieee power & energy magazine
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https://aris.iaea.org/publications/smr-book_2018.pdf https://aris.iaea.org/publications/smr-book_2018.pdf https://www.smrroadmap.ca/
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