1. What is SMR-160?
  2. What are the main benefits of SMR-160?
  3. What is SMR-160’s land area requirement?
  4. Is SMR-160 an “advanced” reactor?
  5. How tall is SMR-160?
  6. How safe is SMR-160?
  7. Why is the SMR-160 described as “walk away” safe?
  8. How difficult would it be for an owner to obtain nuclear fuel to burn in SMR-160?
  9. How will the plant handle its used fuel?
  10. Can SMR-160 be operated in a water-challenged region?
  11. Why does Holtec assert that SMR-160 will be secure against threats of all kinds?
  12. What is the benefit of distributed power provided by SMR-160?
  13. Why would SMR-160 cost less than a large modern nuclear plant on a per kilowatt basis?
  14. What is the service life of SMR-160?
  15. What is the basis for claiming 80 year minimum service life for SMR-160?
  16. What underlies Holtec’s belief that the O&M cost of SMR-160 will be lower than the current generation of plants?
  17. Can SMR-160 follow the electric power demand?
  18. How will SMR-160 meet the federal dose limit at its site boundary despite the small size of its site?
  19. Is the SMR-160 design decommissioning friendly?
  20. What is Holtec’s secret for achieving the highly competitive capital economics despite the small size of SMR-160?
  21. What is SMR-160’s best opportunities for application?
  22. How does SMR-160’s design deal with aging issues?
  23. How is Holtec’s intellectual property related to SMR-160 protected?
  24. What is Holtec’s experience in designing gravity-driven systems for nuclear plants?
  25. What is Holtec’s experience in designing nuclear systems that can withstand severe environmental phenomena or terrorist acts?
  26. What does Holtec aim to accomplish by developing SMR-160?
  27. Wouldn’t the cost of an SMR-160 power plant be more than that for a large (1000+ MWe) nuclear power plant (on a $/kwe basis) because of the latter’s size advantage?
  28. How will the used fuel produced by the plant be handled?
  29. How does the integrated fuel storage system contribute to the safety of the local community around an SMR-160 facility?
  30. How will an SMR-160 perform in the face of a Fukushima-type earthquake and tsunami?
  31. Why is SMR-160 called “walk-away” safe?
  32. What is “grid stability” and how does SMR-160 promote it?
  33. What would be the clean water output of a single SMR-160 if it is exclusively used for desalination?
  34. Can SMR-160 be used to produce both electricity and process steam for, say, desalination?
  35. What is the basis for the claim that SMR-160 will operate for 120 years or more, if maintained properly?
  36. Can SMR-160 be used to “load following”?
  37. How close to the SMR-160 plant can people live?
  38. How safe is an SMR-160 if it were to be struck by a crashing aircraft?
  39. How and when will factory manufactured SMR-160s be available for deployment and use?
  40. Why is SMR-160 friendlier to the environment in terms of tritium release than other commercial reactors?
  41. How was 160 MWe electric output chosen as the basis for sizing the SMR-160?
  42. What are some high-level features of SMR-160 which make it amenable to emerging industrial economies and societies?


Q1:   What is SMR-160?

Response:    SMR-160 is a small modular pressurized water nuclear reactor power plant that does not rely on any pumps or motors to remove heat from the nuclear fuel, for all normal and accident scenarios. (Reactors that produce less than 300 Megawatts of electricity are classified as  “small”.  Modular reactors are manufactured at a plant and assembled at the site.  Modular also refers to the combining of multiple power units into a single power plant.)

Q2:  What are the main benefits of SMR-160?

Response:    The principal strengths of SMR-160 are 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 significant systems must be powered by natural circulation under all performance modes.  For safety and security all engineered safety features of the plant are inside containment protected further by the concrete enclosure structure.

Simplicity of design begets lower operating and maintenance burden and dispenses with the need for a large pool of nuclear scientists and engineers, making SMR-160 a viable source of energy for developing economies.  The small footprint of the SMR-160, along with the optional air-cooled condenser, along with a right-size 160 MWe yield a design that is highly flexible for location and utility.  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.

Q3:  What is SMR-160’s land area requirement?

Response:    An SMR-160 installation takes up less than 4.5 acres of land; this is a fraction of the land area required by other types of power plants on a per megawatt basis. A tractor-trailer at the plant’s truck bay shown in the view below gives a sense of the plant’s size.  The nuclear island portion of the SMR-160 would easily fit on a conventional soccer field (see line drawing below).

16 - without words

Q4:   Is SMR-160 an “advanced” reactor?

Response:    No. The term “advanced” reactor is used to denote futuristic reactor designs that use molten salts, liquid metals or gasses as coolants to remove energy from their nuclear cores. 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 only in the sense that it exploits gravity to drive passive plant cooling to levels of safety unattainable by large conventional nuclear power plants.

Q5:   How tall is SMR-160?

Response:    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.

Picture4

Q6:   How safe is SMR-160?

Response:    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 – 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 systems that are important-to-safety – 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 or heat exchangers are needed to ensure that the plant remains safely cooled and contained.  The SMR-160 is walk-away safe!

Q7:   Why is the SMR-160 described as “walk away” safe?

Response:    Because the nuclear plant can look after itself and keep all its nuclear fuel safe, cool and undamaged within the reactor, fuel pool and integrated UMAX fuel storage canisters, in the case of any unforeseen and unforeseeable cataclysmic event. The plant operators are not required to take action to ensure absolute and certain indefinite cooling occurs. This is possible because SMR-160 does not depend on any man made machine or electrically-powered pumps or motors for its safety function; relying exclusively on Mother Nature’s gravity instead. Under extreme environmental events – like the one that befell Fukushima – SMR-160 behaves like a simple, large passively cooled heat exchanger, relying on Holtec International spent fuel storage technology – proven, licensed and employed at over 100 operating nuclear power plants around the world today.


Q8: How difficult would it be for an owner to obtain nuclear fuel to burn in SMR-160?

Response:    SMR-160 uses commonly available nuclear fuel pellets in zircaloy tubes (fuel rods) manufactured by many qualified suppliers around the world. The SMR-160 fuel design incorporates currently available parts and materials, making it easy for a supplier to tool up to manufacture. Geographically diverse source of supply eliminates owner’s reliance on any one country, for security of supply and competitive pricing.

Q9:   How will the plant handle its used fuel?

Response: 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 subterranean cavities (formally known as Holtec’s HI-STORM UMAX system licensed by the USNRC), occupying 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 and hardened against extenuating threats such as a crashing aircraft or an incident missile.

HH27_19-ISFSI-Pic

Q10:   Can SMR-160 be operated in a water-challenged region?

Response:    Unlike typical power plants, SMR-160 does not need to be sited next to a river, a lake or a sea.  It is engineered to optionally reject its waste heat directly to the atmosphere using air-cooled condensers. Indeed, an SMR-160 plant can be sited in a corn field or a desert. Water scarcity is a huge emerging problem for the world, and we must operate power plants without water cooling to preserve and create this precious resource. According to a recent report, one-third of Earth’s largest groundwater basins are under threat because humans are draining so much water from them.

Recent studies have found that 8 of the world’s 37 largest aquifers are “overstressed,” meaning insufficient water is replenished to offset usage. Topping the list of overstressed aquifers is the Arabian Aquifer System, located beneath Yemen and Saudi Arabia, from which 60 million people draw their water. The situation in the Indian subcontinent is even more severe.

Q11:  Why does Holtec assert that SMR-160 will be secure against threats of all kinds?

Response:    SMR-160 is engineered to be an extremely secure modern industrial installation. Consider the following:

  1. SMR-160 protects its important equipment – needed for safe operation and cooling – with a monolithic steel and concrete shield, impregnable to natural disasters, or to a crashing fighter plane or commercial airliner.
  2. SMR-160’s nuclear commodities lie deep below the ground; making them inaccessible to direct assault by drones or missiles (underground portion of the plant shown in the cutaway view below).
  3. SMR-160’s small land area requirement and simple plant perimeter design lends itself to full monitoring & surveillance using a small security force.

Picture1

  1. During operation, SMR-160 containment enclosure structure is closed and secure to prevent entry, securing the reactor core and spent fuel pool.
  2. SMR-160 control room is underground with multiple layers of security for personnel entry.


Q12:  What is the benefit of distributed power provided by SMR-160?

Response:    SMR-160 is designed to produce 160 megawatts of electricity. It is intended to serve as a distributed energy source, dispensing 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.

The above said, 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 preferable from a power output sustainability standpoint than a single 1600 MWe large reactor. Shutting down or refueling the large plant takes 1600 MWe off the grid at one time, while incremental service and refueling to one SMR-160 in a ten unit cluster eliminates that large single-shaft dilemma, assuring sustainable stable power to the local grid and dependent users.

Q13:  Why would SMR-160 cost less than a large modern nuclear plant on a per kilowatt basis?

Response:    The data on the capital cost of nuclear plants shows the counter-intuitive fact that the per-kilowatt capital cost of plants has risen as they have become larger. The driver for this monotonic increase in per kW capital cost with increasing plant power output is the use and dependence on redundant active safety system, which increase as plants become bigger, with increased complexity and cost.  In short, increased complexity overwhelmed the benefit of largeness of large reactors.

Small modular reactors, in general, eschew complexity and size, seeking to return the economics of nuclear power to its early days before the arrival of the behemoths.

Q14:  What is the service life of SMR-160?

Response:    Eighty years minimum. With proper pro-active maintenance, a one hundred year service life should be achievable.

Q15:  What is the basis for claiming 80 year minimum service life for SMR-160?

Response:    Eighty year service life is supported by several sound technical facts, viz.:

  1. Moving machinery such as pumps are amongst the first to wear out in a plant; SMR-160 uses no pump at all in any safety function. Instead it relies on gravity to run the plant.
  2. The gravity driven flow in SMR-160 is quite gentle, mitigating the incidence of internal maladies such as wear, erosion and flow induced vibration.
  3. Although SMR-160 is a pressurized water reactor, it does not use boric acid in its reactor coolant system. Thus the corrosive effect of boric acid on the plant’s internals will not afflict SMR-160.

Many PWRs that use multiple forced flow from pumps and that utilize boric acid are licensed for 60 years. Supported by reliable performance, several are planning license extensions to 80 years. In light of the above industry experience, it is reasonable to expect that SMR-160 should provide an active service life of at least 80 years.

Q16:  What underlies Holtec’s belief that the O&M cost of SMR-160 will be lower than the current generation of plants?

Response:    In designing SMR-160, Holtec has carefully analyzed operating plant data from the nuclear power industry in order to identify the underlying reasons for current O&M costs. The major contributors to the maintenance burden were thus identified and rooted out from SMR-160’s design. Furthermore, it stands to reason that a plant that is essentially composed of passive components and systems should be a low maintenance facility.

Operating cost, on the other hand, is largely influenced by regulation and industry procedures. The number of control room operators, sharing of operators amongst multiple co-sited units, size of the security staff, etc. for SMRs are matters of ongoing policy enunciation in the United States. The operating cost of SMRs in the United States will largely depend on NRC’s position in such matters.  We believe that the evolving regulatory position in such areas in the U.S. will be risk informed and thus less onerous than those applied to large reactors.

Security force staffing requirements are a significant operating cost in many regulated markets. In foreign countries, where a plant’s security may be provided by national armed forces, staff sizing and operating cost is apt to be substantially improved.

Q17:  Can SMR-160 follow the electric power demand?

Response:    Yes, SMR-160 can be configured to load-follow; however, fuel utilization efficiency will decline and maintenance cost will rise.  SMR-160’s ability to load-follow without excessive internal metal fatigue is, in a manner, another bonus of the gravity driven design.  The nature of density driven flow is such that as the heat generation from the core is throttled, the reactor coolant temperature profile changes but the mean coolant temperature remains substantially constant.

Q18:  How will SMR-160 meet the federal dose limit at its site boundary despite the small size of its site?

Response:    Despite the small land area of the plant, SMR-160 will accrete a small fraction of the dose of a large contemporary reactor at its site boundary because of the many dose mitigation features built into its design, viz:

  1. The size of the reactor’s nuclear core is a fraction of those of large conventional nuclear power plants, with an attendant small radioactive source term.
  2. The most significant dose emitting commodities (core and spent fuel) lie deep underground, their upwards radiation blocked by greater than 20 feet of water and shielded closure heads.
  3. The slow upward flow of water insures that the short lived radioactive gases produced by fission die off before the reactor coolant reaches the above-ground portion of the plant (another bonus of gravity driven flow!).
  4. The slow up-flow of water in the reactor vessel insures that little radioactive crud produced from long term operation carries to the above-ground portion of the reactor coolant system.
  5. Absence of boric acid in the reactor coolant helps reduce crud generation in the core.


Q19:  Is the SMR-160 design decommissioning friendly?

Response:    Yes, SMR-160 has been designed with the aim to minimize decommissioning costs. Among the features that will help an efficient and economical decommissioning of SMR-160 are:

  1. The SMR-160 is designed to simply remove all major equipment out of the containment building through its removal and flanged lids.
  2. The severe activation of metal is limited to the bottom 20 feet of the reactor vessel which lies deep underground encased by a thick concrete enclosure. The upper region of the reactor will experience minimal activation.
  3. Other major equipment such as the steam generator and the pressurizer will experience minimal irradiation (because of the attenuation of radioactive gases and lack of crud carry-over mentioned above) making them (likely) eligible for “free release”.
  4. Except for the reactor coolant system and the fuel pool, the balance of the SMR-160 plant is essentially sequestered from radiation.


Q20:  What is Holtec’s secret for achieving the highly competitive capital economics despite the small size of SMR-160?

Response:    Our best cost estimate indicates that a SMR-160 plant can be installed turnkey by Holtec for less than half of the projected cost of the large nuclear plants on per kilowatt basis (being built in the US, France, and Finland today).  Constructed in one third of the time needed to build current large nuclear power plants, the time value of capital is a significant contributor to the low capital cost.

Simple gravity driven passive fluid flow systems not only hardens the plant against disasters, but also leads to huge reductions in the plant overnight capital cost.

Q21:  What is SMR-160’s best opportunities for application?

Response:    SMR-160 can be sited at the center of an industrial cluster to provide safe, dependable, carbon-free electrical energy or industrial steam to power a variety of industries such as desalination and hydrogen generation.

The relatively low capital cost of SMR-160 and high availability (over 95% capacity factor) makes it an ideal source of economical and reliable power to promote industrial growth.

The expected service life of 80 years makes SMR-160 a sound long-term infrastructure investment to sustain industrial growth & to promote economic well-being.

Q22:  How does SMR-160’s design deal with aging issues?

Response:    The SMR-160 plant is configured to mitigate the contributing causes that are known to induce aging through:

  1. Minimized cumulative radiation (fluence) on load bearing parts and welds.
  2. Reduced Generation of crud with its high corrosive species.
  3. Use of demineralized (rather than corrosive borated) water.
  4. Minimization of mechanical aging effects such as flow induced vibration, metal fatigue and the like.
  5. Maintaining material temperatures well below the limit at which deleterious effects such as stress corrosion cracking may occur.


Q23:  How is Holtec’s intellectual property related to SMR-160 protected?

Response:    The SMR-160 technical innovations that underlie the heretofore unattainable level of safety are documented in an array of patent filings which provide intellectual property protection to the Company.

Q24:  What is Holtec’s experience in designing gravity-driven systems for nuclear plants?

Response:    The intellectual core of the SMR-160 is gravity-actuated flow (passive flow) which is an area in which Holtec is a world leader.  Holtec’s gravity–driven fuel storage equipment is in use at over 120 nuclear plants, world-wide, many for nearly three decades.

Q25:  What is Holtec’s experience in designing nuclear systems that can withstand severe environmental phenomena or terrorist acts?

Response:     Holtec is also an industry leader in designing nuclear systems to withstand cataclysmic natural events such as severe flood, hyper-wind, tornado, tsunami, fire, earthquake, and human mendacity such as a crashing aircraft or missiles, providing absolute and certain safety to the surrounding communities and environment. The company has produced hundreds of technical reports using its proprietary computer codes for operating nuclear plants, and has performed numerous tests to validate its computer codes.

Q26:  What does Holtec aim to accomplish by developing SMR-160?

Response:    We believe that lack of reliable electrical energy stunts human enterprise, and is a root cause of poverty for much of the world.  Our ultimate mission is to light up energy starved (ill-lit areas, see satellite photo below) 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 surety of energy supply to nation’s critical infrastructures in this age of rising domestic terror.

earthlights2_dmsp_big

Q27: Wouldn’t the cost of an SMR-160 power plant be more than that for a large (1000+ MWe) nuclear power plant (on a $/kwe basis) because of the latter’s size advantage?

Response:    No. On a dollar per unit of electricity produced basis, SMR-160’s cost is reckoned to be much less than the large nuclear plants. This is because of SMR-160’s complete reliance on gravity to run the reactor and all safety systems. Gravity, with natural circulation flow, underpins all aspects of SMR-160’s operation, and as such, SMR-160 plants contain less than 60% of the active safety system equipment and machinery needed by large nuclear power stations. Furthermore, the SMR-160 incorporates a dramatically simplified balance-of-plant and steam cycle solution (as compared to traditional large plants), with associated substantial savings in BOP equipment capital and maintenance costs. Additionally, SMR-160s will be substantially factory built and site assembled. To facilitate shop manufacturing (typified by lower cost & better quality assurance), all SMR 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.


Q28: How will the used fuel produced by the plant be handled?

Response:    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 subterranean cavities (formally known as Holtec’s HI-STORM UMAX system licensed by the USNRC), occupying 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 and hardened against extenuating threats such as a crashing aircraft or an incident missile.


Q29: How does the integrated fuel storage system contribute to the safety of the local community around an SMR-160 facility?

Response:    The storage facility, which is located below ground, contains most of the irradiated fuel rods at an SMR-160 plant site. The amount of fuel within the SMR-160 buildings is less than 10 % of that stored at a typical present day nuclear plant. Furthermore, the fuel inside the power plant facility is maintained within the plants large metal containment structure, and is constantly protected and cooled by passive safety features. SMR-160 is the only nuclear power plant in the world – operating or proposed – to both limit the spent fuel volume to such a small inventory and protect it with the containment, while assuring unlimited cooling. Incorporating an interim fuel storage system (HI-STORM UMAX) into the base SMR-160 plant offering is a first-of-a-kind feature for any nuclear power plant, and will eliminate the need for major subsequent plant modifications and upgrades later in plant life, typically in excess of $100M.


Q30: How will an SMR-160 perform in the face of a Fukushima-type earthquake and tsunami?

Response:    The Fukushima accident happened when flooding of power plant safety systems caused by the tsunami prevented operation of pumps needed to cool the nuclear fuel within the reactor and the fuel storage pools, causing that irradiated fuel to overheat. In the SMR-160 power plant, the inventory of fuel in both the pool and the reactor is a fraction of that in large reactors, and that entire fuel inventory is kept cool without any reliance on pumps and motors. Furthermore, no credible event has been identified that would uncover the nuclear fuel in the reactor vessel or the spent fuel pool. Therefore, SMR-160 will withstand a Fukushima-type earthquake and tsunami without any risk to public health and safety.


Q31: Why is SMR-160 called “walk-away” safe?

Response:    Because the nuclear plant can look after itself and keep all its nuclear fuel safe, cool and undamaged within the reactor, fuel pool and integrated UMAX fuel storage canisters, in the case of any unforeseen and unforeseeable cataclysmic event. The plant operators are not required to take action to ensure absolute and certain indefinite cooling occurs. This is possible because SMR-160 does not depend on any man made machine or electrically-powered pumps or motors for its safety function; relying exclusively on Mother Nature’s gravity instead. Under extreme environmental events – like the one that befell Fukushima – SMR-160 behaves like a simple, large passively cooled heat exchanger, relying on Holtec International spent fuel storage technology – proven, licensed and employed at over 100 operating nuclear power plants around the world today.


Q32: What is “grid stability” and how does SMR-160 promote it?

Response:    The voltage on a power grid is held in equilibrium by insuring that the electricity produced equals the electricity demanded at every instant. A large power plant coming either on line 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). A cluster of SMR-160s, therefore, is more congenial to a power grid’s stability than an equivalent single reactor unit. 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 susceptibility of those systems to instability by alleviating the large single-shaft power dilemma that large reactor plants introduce.


Q33: What would be the clean water output of a single SMR-160 if it is exclusively used for desalination?

Response:    An SMR-160 produces 1.55 x 106 lbm of steam per hour. Using a quadruple-effect evaporator, this pressurized steam can be used to produce 6.2 x 106 lbm of demineralized water per hour, or 3100 tons per day. A quadruple-effect evaporator, by definition, will produce four pounds of condensate (essentially salt-free water) for each pound of steam yield.


Q34: Can SMR-160 be used to produce both electricity and process steam for, say, desalination?

Response:    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. The use of the energy from SMR-160 is entirely up to the owner.


Q35: What is the basis for the claim that SMR-160 will operate for 120 years or more, if maintained properly?

Response:    We expect SMR-160 to produce power for 120 years because all failure modes that have felled reactors in the past have been rooted out from its design. For example:

  • The reactor vessel is subject to cumulative neutron fluence in 120 years of operation that is less than that has been experienced by presently operating reactors.
  • The number of pressure boundary welds in SMR-160 reactor cooling system is less than half of that in a large reactor and even more important, every weld is accessible for in-service inspection making the monitoring of their integrity an easily executed process.
  • The SMR-160 reactor employs no material that is vulnerable to degradation in its applicable environment. By eliminating boron and other corrosive material typically used in large nuclear plants and other SMRs, the propensity for fouling and reactor components stress corrosion cracking has been dramatically reduced.
  • With its unique flanged containment head and equipment layout, all major equipment (e.g. steam generator) is easily and affordably replaceable, dramatically extending the plant operating lifetime.


Q36: Can SMR-160 be used to load follow?

Response:    Yes. All practical commercial power reactors must be capable of quickly adapting to the changing demand on the electric grid, more important today with increased grid contributions from unsteady (e.g., non-constant) solar and wind sources, and SMR-160 ideally suits that need. SMR-160 is designed to change its power output quickly, up or down, with power ascension capability from 30% to full power at a rate of 2.5% per minute. That rate facilitates a change from low to full power in less than 30 minutes, ideal for today’s changing demand and grid makeup. The gravity driven reactor cooling system adapts naturally to changing power demand. However, to maximize service life, it is recommended to run this reactor as a base load facility, not as a “peaking” unit.


Q37: How close to the SMR-160 plant can people live?

Response:    The so-called Exclusion Zone around any nuclear power plant is a mandated buffer space, dictated by the plant’s regulator. The competent Authority (viz., the USNRC) decides on the size of the Exclusion Zone, based on the characteristics and safety performance of the plant in question. Guided by the minuscule radiological matter release that can occur in the wake of the most severe disruptive event at an SMR-160 site, the regulator is expected to demand a small buffer zone. That said, while significant progress is being made the position to technically substantiate the need for very small Exclusion Zones for plants like SMR-60, no final determination of this matter has yet been made by any of the world’s national regulators.


Q38: How safe is an SMR-160 if it were to be struck by a crashing aircraft?

Response:    The nuclear material in an SMR-160 plant (both the reactor vessel and the fuel pool) is located deep in the ground. In addition, the containment vessel is surrounded by a 6 foot thick steel & concrete structure known as the Containment Enclosure Structure. This extremely robust shield structure is designed to remain operational if struck by a crashing Boeing 757. In summary, there is no pathway for an incident missile or aircraft to access or expose the nuclear material in an SMR-160 power plant.


Q39: How and when will factory manufactured SMR-160s be available for deployment and use?

Response:    Holtec International is completing construction of the world’s first dedicated SMR manufacturing facility, today. That factory, sited on the Delaware River in NJ, USA, 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, scheduled for commercial operation by the beginning of 2018, is expected to be the first of multiple such facilities, both in the United States and around the world. As America’s largest capital nuclear equipment exporter, Holtec International has significant experience with massive nuclear equipment manufacturing and localization issues and opportunities.


Q40: Why is SMR-160 friendlier to the environment in terms of tritium release than other commercial reactors?

Response:    Unlike most all PWRs and light water SMRs, SMR-160 does not rely on boron as a reactivity control agent or shim. Tritium is produced primarily from neutron capture by B-10 in PWRs; that B-10 (in the form of boric acid) is added to reactor coolant systems as a soluble reactivity agent. SMR-160’s tiny tritium inventory results from that lack of boric acid in the system. For context, 90% of the total tritium produced in PWRs and light water SMRs is produced by B-10 neutron capture. For those reactor plants, the tritium builds up in their Spent Fuel Pools during refueling operations. Resulting large tritium inventories require ventilation and filtration systems to prevent environmental consequences from atmospheric and ground water releases and leaks. Designed without the need for boric acid control, SMR-160 is uniquely safe and environmentally friendly amongst all SMR offerings in the marketplace today.


Q41: How was 160 MWe electric output chosen as the basis for sizing the SMR-160?

Response:    Ideally, SMRs should be readily able to slot into brownfield sites in place of decommissioned coal-fired plants, the units of which are seldom very large. More than 90% operating in the word today are under 500 MWe, and some are under 50 MWe. In the USA coal-fired units retired over 2010-12 averaged 97 MWe, and those expected to retire over 2015-25 average 145 MWe. A 160 MWe 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 proximate to major grid infrastructure and city-centers, and to facilitate simple passive rejection of a limited decay waste heat.


Q42: What are some high-level features of SMR-160 which make it amenable to emerging industrial economies and societies?

Response:    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 LLWRs and lacking boric acid shim, 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.