Frequently Asked Questions
SMR-160 is a small modular pressurized water nuclear power plant that does not rely on any pumps or motors to remove heat from the nuclear fuel, for all accident scenarios. The SMR-160 produces net 160 Megawatts electric (MWe) power or 525 Megawatts thermal (MWt) for process applications. The SMR-160 represents innovation through simplification and use of entirely passive safety systems, while relying on decades of proven operating history for the existing commercial pressurized light water reactor fleet. Generally, reactors that produce less than 300 MWe are classified as “small.” Reactors dubbed to be modular rely on the plant being substantially manufactured in a factory environment and are comprised of pre-built assemblies to reduce on-site construction cost and schedule.
The principal strengths of SMR-160 include its inherent safety, robust security, simple and reliable operation, flexible application, rapid constructability and competitive economics.
The SMR-160 design is driven by the principal criterion that all safety systems must be passive and use natural circulation under all performance modes. All safety systems of the plant exist inside containment and are protected further by the concrete enclosure structure.
Simplicity of design and automated control results in lower operating and maintenance burden, and decreases with the need for a large pool of nuclear scientists and engineers to operate the plant, making SMR-160 a viable source of energy for developing economies.
The SMR-160 is highly flexible for location and utility. It has a small footprint, can use air-cooled condensers in water scarce locations if needed, and can be placed in both highly populated or remote locations. Because SMR-160 is walk-away safe, it can be sited next to population centers without any threat to the local environment or populace. Placing SMR-160 close to cities and towns will reduce transmission losses and enable the plant’s workers to live in the local community.
An SMR-160 installation takes up less than five acres of land for a single unit deployment. This is a fraction of the land area required by other types of power plants on a per megawatt basis. For comparison, the nuclear island of the SMR-160 would easily fit on a conventional soccer field. No emergency planning zone is required outside the fence-line, as is typically necessary for larger reactors.
SMR-160 is a conventional fission reactor, using water as the cooling medium, and is designed with six decades of world-wide industrial operating experience with pressurized water reactors. The SMR-160 is advanced in the sense that it exploits gravity to drive passive plant cooling to levels of safety unattainable by large conventional nuclear power plants. Most critically, the nuclear fuel that powers this reactor is commercially available right now and does not require any complicated research.
The tallest SMR-160 plant structure is similar in height to a small city water tower. A significant portion of the SMR-160 power plant lies below grade to improve security and safety aspects of the plant.
Informed by over six decades of lessons learned from reactor operations, SMR-160 is designed to be an extremely safe power plant. Every conceivable catastrophic event, including severe cyclones (hurricanes or typhoons), tsunamis, flood, earthquakes, fire and crashing aircraft, has been considered in SMR-160’s design basis and appropriate features incorporated to ensure that it will withstand these events without damage to itself, nor impose any risk to public health and safety.
All safety systems that are used to ensure that the plant’s nuclear fuel is always cooled, are run purely by gravity. Unlike large nuclear power plants, no electrically-powered pumps are needed to ensure that the plant remains safely cooled and contained. The SMR-160 is walk-away safe.
The SMR-160 is walk-away safe because the nuclear plant can keep all its nuclear fuel safe, cool and undamaged within the reactor, spent fuel pool and integrated HI-STORM UMAX (Holtec International Storage Module Underground MAXimum Capacity) underground spent fuel storage canisters, in the case of any unforeseen catastrophic event. The plant operators are not required to take action to ensure cooling occurs. This is possible because SMR-160 does not depend on any man-made machine or electrically-powered pumps; it relies exclusively on gravity. Under extreme environmental events, like the one that occurred at Fukushima, SMR-160 behaves like a simple, large, passively cooled heat exchanger relying on the same safety principles that Holtec International’s spent fuel storage technology employs at over 100 operating nuclear power plants around the world today.
SMR-160 uses a commonly available nuclear fuel assembly manufactured by many qualified suppliers around the world and is commercially available today as an off the shelf component. The enrichment required for the core design is typical for light water reactors operating now, without any requirement for additional supply chain development.
Unlike currently operating nuclear reactors, SMR-160 has been designed to store the used fuel produced over the entire operating lifetime of the plant in on-site subterranean cavities in Holtec’s HI-STORM UMAX system, which is licensed by the U.S. Nuclear Regulatory Commission (NRC) and has been deployed for commercial use. This occupies a small parcel of land in the plant’s backyard. The storage cavities contain the irradiated fuel bundles in welded multi-purpose canisters, with over-packs hardened against extenuating threats such as a crashing aircraft or an incident missile.
Spent fuel from the entire 80-year design life of the SMR-160 can be stored in just 24 HI-STORM UMAX modules. For context, the image below depicts a real HI-STORM UMAX installation at a currently operating nuclear power plant. For 80 years of operation, a HI-STORM UMAX installation just half this size is required to safely store the SMR-160’s spent fuel on-site until final storage or reprocessing is required.
Yes, SMR-160 does not need to be sited next to a river, a lake or sea unlike typical power plants. It is engineered to have an option to reject its waste heat directly to the atmosphere by utilizing its cutting-edge capability to operate using an air-cooling system in lieu of a large quantity of water. With the flexibility to use air-cooled condensers, SMR-160 can be deployed in the most arid regions of the world, such as a desert.
SMR-160 is engineered to be an extremely secure and modern industrial installation. Consider the following:
- SMR-160 protects its safety systems within a monolithic steel and concrete shield, impregnable to natural disasters or security threats.
- SMR-160’s components lie deep below the ground, inaccessible to direct assault by drones or missiles.
- SMR-160’s small land area requirement and simple plant perimeter design lends itself to full monitoring and surveillance using a small security force. The small land area is also readily adapted to a remote or automated security monitoring program.
- During operation, SMR-160’s containment is closed and secured, protecting the reactor core and spent fuel pool.
- The SMR-160 control room is underground, with multiple layers of security. Further, the control system is distributed to eliminate the possibility of catastrophic failures and designed to ensure that any human action, intentional or not, is unable to override the safe operation of the plant.
Yes, SMR-160 is intended to serve as a distributed energy source, reducing with the need for expensive high capacity transmission lines over long distances. This makes multiple-unit based SMR-160 electricity supply more resistant to natural disasters or acts of sabotage and eliminates the need and cost of building traditional grid infrastructures. Distributed power provided by a string of SMR-160s will promote grid stability and render a nation’s power supply very resistant to disruption.
There is no limit to the number of SMR-160 reactors that can be arrayed side-by-side at a site. A cluster of ten SMR-160s, producing a total of 1600 MWe is more preferable from a power output sustainability standpoint than a single 1600 MWe large reactor. Shutting down or refueling a large plant takes 1600 MWe off the grid at one time, while incremental service and refueling of one SMR-160 in a ten-unit cluster assures sustainable stable power to the local grid and dependent users.
The SMR-160 design contributes to substantial savings in equipment capital and maintenance costs. The SMR-160 ensures that systems, structures, and components across the plant are designed and right-sized for their functions, and incorporate a level of passivity that achieves a vastly safer plant without the need for additional redundancy.
Additionally, SMR 160s will be substantially factory built and site assembled. To facilitate shop manufacturing), all SMR-160 components are limited to 12 feet in diameter and practical maximum weights to facilitate flexible shipping options to destinations around the world. Minimizing shipping limitations for massive large power plant components introduces significant cost savings.
At a minimum, the service life of SMR-160 is 80 years. With proper pro-active maintenance, a 100-year service life should be achievable.
Yes, the SMR-160 is designed to change its power output quickly, up or down. The gravity driven reactor cooling system adapts naturally to changing power demand. However, to maximize fuel economy and minimize maintenance costs, it is preferable to run the reactor as a base load facility, not as a “peaking” unit.
Yes, SMR-160 has been designed to support the safe and efficient decommissioning of the plant in the future:
- Reduction of the radiation source (the reactor’s nuclear core is a fraction the size of that present in large conventional nuclear power plants)
- Plant layouts that limit the spread of contamination facilitate dismantling and decontamination of radioactive equipment (SMR-160 is designed to simply remove all major equipment out of the containment building through its hatches and flanged lids)
- Simplification of waste management systems and careful management of radiological data and design information to facilitate decommissioning
Further, the design of SMR-160 is supported by the leadership and experience from Holtec subsidiary Holtec Decommissioning International (HDI).
The SMR-160 plant is configured to mitigate the contributing causes that are known to induce aging through:
- Minimized cumulative radiation (fluence) on load bearing parts and welds.
- Reduced generation of crud with its high corrosive species.
- Minimization of mechanical aging effects such as flow induced vibration, metal fatigue and the like.
- Maintaining material temperatures well below the limit at which adverse effects such as stress corrosion cracking may occur.
- Instrumentation and control systems are designed with a strategy to manage obsolescence over plant life.
- All components are designed for either full-service life or are readily accessible for replacement without major plant modifications.
Holtec is also an industry leader in designing nuclear systems to withstand catastrophic natural events such as severe flood, tornado, tsunami, fire, earthquake, and security threats such as a crashing aircraft or missiles, providing absolute and certain safety to the surrounding communities and environment.
Holtec’s mission is to provide energy starved areas of the world with safe, secure, affordable pollution-free energy, through hundreds of SMR-160s operating around the world.
To a developing world, SMR-160 will provide grid stability and security of energy supply to nations’ critical infrastructure. Further, SMR-160 is a critical component to combating climate change via transition to zero-carbon power generation sources.
The voltage on a power grid is held in equilibrium by ensuring that the electricity produced equals the electricity demanded at every instant. A large power plant coming either online or going offline causes a substantial swing in the power produced within that grid system, and can cause large fluctuations in the systems voltage, affecting the grid’s stability and reliability. A single SMR-160 out of a group of five (in lieu of a single 800 MW plant), for example, is far less impactful in affecting the grid’s voltage (i.e., its stability). Furthermore, in order to ensure that grid stability is maintained, grid systems must have standby or replacement power supplies immediately available when large power plants go offline. SMR-160s greatly reduce the instability of those systems by alleviating the large power dilemma that large reactor plants introduce.
Yes. An owner may decide what portion of the energy output of the plant will be used to produce electricity and what fraction will be directed for other purposes, such as desalination. Because the secondary loop of the SMR-160 is entirely clean of radioactivity and the plant has a relatively high thermal power, the design is amenable for applications requiring process steam such as industrial processes, district heating, or desalination. The use of the energy from SMR-160 is entirely up to the owner.
As America’s largest capital nuclear equipment exporter, Holtec International has significant experience with major nuclear equipment manufacturing. The company has completed construction of the world’s first dedicated SMR manufacturing facility in Camden, New Jersey. The factory has the lifting, cutting, welding, cladding, drilling, machining, inspection, and shipping capacities necessary for all of the SMR-160’s capital nuclear equipment fabrication needs. This state-of-the-art facility is expected to be the first of multiple such facilities, both in the United States and around the world.
SMR-160 was identified as a near-optimum size to back-fit existing grids and brownfield sites for retiring fossil units, to suit the power needs of communities and industrial complexes not located near major grid infrastructure and city-centers, and to facilitate simple passive rejection of a limited decay waste heat.
A short list of compelling features includes:
- Small power, compact architecture, and complete reliance on passive safety to ensure certain safety for the public and plant personnel.
- The compact architecture enables modularity of fabrication, facilitating localization of manufacture for industrial development, along with implementation of higher quality standards than stick-built traditional plants.
- Lower power than existing large light and heavy water reactors, leading to a significant reduction of the source term as well as smaller radioactive inventory in the reactor and spent fuel pool.
- Underground location of the reactor unit, providing incredible protection from natural (e.g. seismic or tsunami according to the location) or man-made (e.g. aircraft impact) hazards.
- The modular design and small size lends itself ideally to having multiple units on the same site.
- Lower requirement for access to cooling water – therefore suitable for remote regions, or those with little or no access to precious or external water sources, and for specific applications such as mining or desalination.
- Ability to easily remove the reactor and steam generator module for simple and/or in-situ decommissioning at the end of the lifetime.
- Long operating life, with an initial design life of 80 years and the potential to extend well beyond that.
- Produces clean, carbon-free heat or energy to support national interests in combating climate change.