Dr. Claudio Filippone is founder and owner of HolosGen, LLC, and one of the world’s pioneers in the development of microreactors. In 2016, a report by the Defense Science Board prepared for the U.S. Congress identified the Holos design as one of the two “most mature – technologically and in operational thinking” very small modular reactors (vSMRs)1 in the world today. His work was subsequently awarded funding from the U.S. government.
Dr. Filippone was also a UxC special consultant from 2008 to 2015, contributing his know-how and nuclear engineering expertise on nuclear reactor technologies and related topics to determine technical, economic, and licensing feasibility of various reactor designs worldwide. His work was reflected in several groundbreaking reports that UxC issued during this period (see project list at end of interview).
This interview was conducted by UxC Chairman Jeff Combs as part of our effort to bring nuclear power advances to light. It has also been published in the January 19, 2021 issue of the Ux Weekly.
UxC: What got you first interested in developing a microreactor?
Dr. Filippone: I became interested in developing microreactors when I was a student in nuclear engineering in the early 1990s at the University of Maryland. At that time, my background and operational experience was on high-power electronics and internal combustion engines. My interests were focused on very compact nuclear power plants configured to satisfy requirements for propulsion systems for space applications, nuclear-powered unmanned submergible vehicles, nuclear engines for marine vessel propulsion, and stationary and transportable nuclear generators that could be deployed anywhere independent of site-specific requirements. Some of my early designs were truly “micro” as, for example, I had developed “wearable” nuclear decay-heat generators based on thermal energy from alpha emitting isotopes conversion to electricity to supply power to soldiers’ equipment (laser guided weapons, back-pack computers) as well as drones that did not need to be refueled for several months. Another design was configured to power Left Ventricular Assist Devices (LVADs) and implantable total artificial hearts for patients unable to obtain human heart transplants. So, my interest in developing microreactors has roots that go back decades. All of the engineering activities I conducted for the support of microreactor designs have in common the need to reduce the size of the heat-to-electric power conversion system, which is traditionally formed by multiple components positioned outside of the pressure vessel housing the nuclear core.
UxC: The microreactor concept really represents a paradigm shift, doesn’t it?
Dr. Filippone: It definitely does. The design offers multiple advantages that are unmatched by other reactor designs when it comes to mobility/transportability, and economics. Holos eliminates the balance of plant (BOP), which results in the reduction of a substantial number of components and cost reduction, while increasing safety as a lower number of components can undergo failures.
UxC: What are the key markets for microreactors? Do you see them competing with other reactor technologies or are they complementary?
Dr. Filippone: There are numerous markets for microreactors as they can be deployed anywhere and do not require a robust power grid; in fact, they can operate as “electric islands,” where the power grid is represented by the microreactor power bus itself. In addition to conventional utility markets, microreactors become increasingly competitive in remote areas where the logistic for fossil fuels, or practicality of renewable energy sources becomes economically unsustainable. Additional markets are represented by miniaturized nuclear power plants aboard marine vessels where propulsion is executed via electric propellers pods. Microreactors are not competing with large baseload reactors, in fact, they are complementary. For example, coupling microreactors to large reactors can ensure load following capability without requiring rapid power rate changes for the large reactor. Large nuclear power plants rely on redundant large diesel generators for emergency power. A microreactor connected to the same large nuclear power plant power grid would ensure emergency power at all times. If the Fukushima Daiichi plant had been connected to a microreactor on or near the site, the world would have not experienced the severe accident that ensued.
UxC: It also seems like microreactors are complementary with other emerging technologies, such as electric vehicles. In this regard, Tesla is looking to introduce electric semi tractor-trailers with a range of 600 miles, but these need charging stations, in some cases in remote areas.
Dr. Filippone: Absolutely. All Holos generators designs are configured to provide relatively high-rate load-following power at any site. For example, the “Holos QUAD,” optimized by Argonne National Laboratory (ANL) and sponsored by the U.S. DOE ARPA-MEITNER program, can generate 10 MWe 24/7 for at least 8 years without refueling. If less power is utilized (load-following capability), the refueling time is further extended. The Holos QUAD can be deployed anywhere, for example on key routes to supply electric power to electric semi-tractor trailers as well as electric cars. In fact, by deploying Holos QUAD generators along main routes, the mileage range requirement for these electric vehicles can be less limiting – the battery pack capacity (and dimensions) can be reduced so that the vehicle becomes even more efficient during accelerations and decelerations, or while tackling routes with steep grades.
UxC: You have met with several political, military, and high-tech leaders during your efforts to promote HolosGen. What has been the reaction to your design?
Dr. Filippone: I have been effectively promoting transportable nuclear generators since 2009, particularly to the U.S. Department of Defense as the need for microreactor capabilities became imperative for national security. When introducing the concept of microreactors and supporting their feasibility with hard evidence the overarching primary reaction is excitement. For example, for military leaders, learning about Holos innovative design features, including its “battle-short” capabilities, accident avoidance through the elimination of the balance of plant and other design features mitigating “design attack basis scenarios,” provokes undeniable excitement. The very attractive features of the Holos design for military applications are rapid mobility when the reactor is “fresh” (not radioactive) and also when the reactor is “hot” (after even short electricity production, the microreactor core becomes radioactive and transporting it requires heavy shielding). Shielding is a serious challenge as the microreactor must comply with the standard International Standard Organization – ISO, shipping container requirements. For these reasons, the Holos QUAD is made of four independent (smaller) fuel cartridges, easier to transport and shield when hot, and forming a full operational core when coupled altogether within a single shipping container. However, there also have been some reservations due to the very innovative design features associated with the Holos QUAD. Technical innovations, especially when disruptive in the marketplace, generally take a long time to be accepted. When innovations are brought to the nuclear industry it takes even longer. The best reactions come from aviation experts as Holos power conversion components are similar to gas turbojet engines for power production and for aviation. After all, the core is a well-known heat source, one of the components of the Holos power plant, the majority of innovation for the Holos microreactor design is represented by the highly integrated, magnetically-levitated power conversion system.
UxC: What do you think sets your Holos design apart from the other microreactors currently under development?
Dr. Filippone: The “Holos” design introduces unique and innovative design features that substantially discriminate the design from other microreactor designs. The great majority of microreactor designs derives from design architectures and plant configurations anticipated by Gen IV advanced reactor designs, and very small reactor developed in the 60s and 70s, for example for the nuclear rocket and nuclear bomber programs. The Holos design eliminates the “balance of plant.” This is one of the most innovative features. The balance of plant is generally represented by networks of hydraulic tubing and electrical conduits normally coupling specialized equipment as heat exchangers, pumps for water or liquid metal system, compressors for gas systems, power turbine and electric generator to convert heat from the nuclear fuel into electricity. The Holos design integrates all of the BOP components, normally outside of the pressure vessel housing the nuclear core, by forming compact assemblies directly coupled to the nuclear core within the same pressure vessel that normally only houses the nuclear core. Another unique innovation is represented by the physical decoupling of the normally mechanically coupled compressor-turbine-generator assembly. In the Holos design, the power conversion components forming the compressor and the power turbine are independent. Their coupling is executed through modern high-frequency commercial electronic drives. This enables high efficiency operation as the rotary speed of the compressor is independent of the rotary speed of the turbine-generator. All of the microreactors and small modular gas-reactor designs proposed worldwide rely on traditional mechanically coupled compressor-turbine-generator. The Holos design features several additional innovations including redundant, independent, and diversified reactivity control systems that exploit the unavoidable neutron leakages at the core periphery and between independent core components. Finally, independent transport of sealed power modules is another innovative and unique Holos design feature of the QUAD concept. This feature enables the power modules to be shielded during transport while in compliance with the dimensional and weight constraints represented by ISO shipping containers.
UxC: What is the key to the puzzle of getting nuclear back on track, especially when it comes to microreactors?
Dr. Filippone: In my opinion, the key to bringing U.S. nuclear technologies back on track requires federal funding managed through a multipronged approach, comprising, for example, fine-tuning the selection process of federal funding programs developed and dedicated to creating nuclear innovation. The multipronged approach would include the creation of a government-driven “Nuclear Technologies Center” (Center) comprised of subject matter experts in all of the components associated with a nuclear power plant. Normally, “nuclear” effectively means only the reactor pressure vessel comprising the core, while every other component of the power plant is effectively “imported” from various non-nuclear industries that adapt their components – for example, heat exchangers, pumps, turbines, digital controllers, sensors, and so on – to work as parts of a nuclear power plant. The emphasis should change so that all components forming the nuclear power plant are designed as a whole system where each component is in harmony with the reactor pressure vessel rather than design adaptations from gas, oil, and coal-fired power plants. The Center should consist of experts from academic institutions, the national laboratories and the NRC, essentially mimicking the “Resource Team” concept, successfully developed and deployed by the U.S. DOE ARPA-E MEITNER program. The Resource Team sponsored by the MEITNER program has provided invaluable support to the feasibility verification of the Holos QUAD features. The Center should provide expert support and a “first comprehensive assessment” of the proposed technologies to all vendors proposing innovative nuclear technologies. The first assessment would effectively execute “fact checker” functions to ensure that proposed nuclear technologies, independently assessed and verified, become eligible for federal funding. All nuclear technologies under development – small, large, and micro that receive federal funding should be required to operate at a total power plant efficiency of greater than 40% to compete with non-nuclear electricity producing technologies. Finally, reforming the intellectual property provisions to be tailored on a case-by-case basis would make easier, especially for start-up nuclear companies, to attract private investment. These are just examples of the several steps to be streamlined to enable merit-based innovative nuclear technologies to timely advance and ensure the U.S. has a technological edge, especially on technologies that support national security.
UxC: Along these lines, how do you think that prospects for microreactors in general and yours in particular will fare under a Biden administration?
Dr. Filippone: President-Elect Biden is a supporter of climate change initiatives and advanced nuclear, so I think that prospects for microreactors will be enhanced. Several microreactor technologies currently funded with federal funds do not have to satisfy a “minimum efficiency” requirement. The lower the efficiency the easier is to manufacture a microreactor. However, the higher the efficiency the more economically sustainable and competitive these designs become while proportionally decreasing thermal rejection (thermal-pollution) in the environment. My hope is that clear and long-term missions will be established to enable funding for innovative nuclear technologies based on highly-efficient microreactors to make them competitive with non-nuclear electricity producing technologies. Further, if properly designed, microreactors should promote the expansion of renewable energy sources, for example by coupling microreactors to non-dispatchable and intermittent solar and wind power plants. All Holos generator designs under HolosGen are configured to contribute to these goals.
UxC: You have worked in various other industries, including automotive, rail, etc. What lessons can the nuclear industry learn from these others?
Dr. Filippone: The nuclear industry can learn substantially from the regulatory environment and quality assurance protocols adopted by the aviation industry. Microreactors as “jet engines” can be factory produced and, if intelligently designed, can be independent of site-specific environmental stressors. Quality assurance for jet engines includes rigorous testing at all known and extreme environmental conditions so that a jet engine qualified to operate in the artic at subzero temperature can also take-off and land at locations near the equator at extreme heat. Similar “qualification requirements” should apply to microreactors. The aviation industry also offers a great model for the control and monitoring of reactors operations. For example, remote centers monitor status of jet engines in flight, and pre-emptively schedule maintenance or repair before anomalies detected during operations develop into catastrophic failures. Microreactors can be designed so they will not require on-site operators. This is another cost-saving item that makes these technologies competitive. These machines are nothing more than drones that sample their power bus at high-frequency and increase/decrease electric power generation based on electricity demand. Equipment developed for rail applications must survive vibratory stressors that can reach several g (acceleration) in all axes. Comparatively stationary power plant must comply with lower accelerations induced by seismic events. Microreactors can encounter substantial accelerations and potential resonance frequencies during transport. For these reasons, all components forming a microreactor must be designed for operation under severe accelerations as for rail equipment.
UxC: Is a rapid buildout of factory-built microreactors realistic in this day and age? Do you see any parallels between the technology advances that allowed the COVID-19 vaccines to be developed so quickly and effectively and the development of microreactors?
Dr. Filippone: A rapid buildout is definitely feasible. Microreactors are literally so small that almost all components can be 3D printed. Advanced manufacturing technologies are available and there are plenty of pre-commercial products (including SpaceX technologies) demonstrating full-scale feasibility before industry standards have been even developed to categorize these new manufacturing methods and 3-D printed materials. HolosGen cooperates and in some cases teamed-up with U.S. and European large manufacturers with advanced manufacturing and “digital” capabilities for “digital twins,” wherein an entire reactor design comprising all of the thermal-physical, heat-transfer, materials, structural, and its electrical and electronic components can be entirely digitally designed and simulated for performance assessment before a single part is manufactured. Microreactors can leverage all of this instantly. Not only microreactors can be rapidly mass-produced by taking advantage of advanced manufacturing and digital simulations, but their size also enables full factory-testing and quality assurance as it is done for jet engines, before a certified operational microreactor is deployed to any given stationary site or mobile applications (e.g., marine propulsion).
UxC Joint Projects with Dr. Claudio Filippone
UxC has been honored to work with Dr. Filippone on numerous projects in the past. The following list presents the highlights of our joint collaborations over the years.
New Reactor Procurement Assessment & Cost Estimates, 2008
In support of a large international utility’s new reactor procurement endeavor, this project provided detailed cost and market data on specified new reactor designs. The report included bottom-up, full scope nuclear power plant (NPP) cost estimates using computer-assisted modeling (CAD) and other tools to analyze cost variations and construction risks for specified Generation III+ reactor designs. In addition, analysis focused on reactor construction techniques, vendor capabilities, and contract optimizations.
Nuclear Reactor Technology Assessments, 2008
A groundbreaking study analyzing the leading large nuclear reactor designs with technical and commercial evaluations that included detailed comparative ratings allowing for unbiased comparisons of the strengths and weaknesses of each design.
Specialty Metals Demand Analysis from New NPPs, 2010
This major client-based project used detailed modeling to create a comprehensive quantification of specialty metals used in the construction of new NPPs. Work was done to identify metals used in each reactor, breaking them out by specific metal/alloy, volume, and product form. In addition, UxC also performed related market analyses to identify the supply chain for each metal, and the procurement lead times and sourcing strategies by metal type.
Small Modular Reactor Assessments, 2010
A groundbreaking 500-page report offering detailed technical, economic, and other commercial assessments of each of the SMR designs being developed within the nascent SMR market around the world as of 2010.
Nuclear Power in the Post-Fukushima Era, 2011
A detailed analysis of the impacts of the Fukushima accident on both a technical and commercial level. This report also offered critical analysis on the various implications of new regulatory requirements and stress test results for reactors around the world.
Nuclear Power Plant CAPEX Model, 2012
As part of a client request, this project resulted in a detailed modeling of all-in capital costs (CAPEX) for the leading international NPP designs with emphasis on comparative economics among key countries, including cost variations between China, Russia, India, U.S., and South Korea. CAPEX for new NPPs were modeled based on design-specific criteria and comparative labor, materials, engineering, and other inputs.
SMR Market Outlook, 2013
This detailed study evaluated the market potential for SMRs around the world and analyzed each of the designs competing in this developing market as of 2013, including independent views on the issues affecting SMRs as well as the relevant features and dynamics likely to influence the SMR market.
Nuclear Plant Economics Workshop, 2015
This special client project involved an in-depth 2-day workshop on nuclear power plant costs and economic considerations. Topics covered included comparative costs of new reactors, factors affecting NPP costs, contracting and cost mitigation strategies, as well as economic considerations of SMRs.
Global Specialty Alloy Tubing Market Analysis, 2015
This special client project focused on providing data and analysis on future market demand for nickel, stainless steel, titanium, and zirconium alloy tubes from NPPs around the world using unique engineering modeling focusing on tubing for key reactor components (e.g., steam generators, heat exchangers, control rod drive mechanisms, reactor vessel internals, condensers, etc.) as well as nuclear fuel assemblies.
1 Department of Defense, Defense Science Board, Task Force on Energy Systems for Forward/Remote Operating Bases Final Report, August 1, 2016. Of the two vSMRs (what we refer to in this interview as microreactors), the Holos design was the only one which consisted of a complete power plant fully comprised in a shipping ISO container.