Small Modular Reactors

The nuclear industry is having a renaissance. People are realizing that renewable energy sources like wind and solar cannot provide customers with energy 24 hours a day, 365 days a year. Environmentalists have been so persuasive in promoting renewables, that we have even legislated power companies to development them only to realize that power companies have to build fossil fuel plants to generate power when there is no sun and/or wind.

The media is starting to report on Small Modular Reactors (SMRs), reactors that “eat” nuclear waste (GEH Prism), and even fusion power (we will believe it when we see it). These reports do describe possible future nuclear power generating designs but not something you can build today. And we must start today if we are to make any dent in our Global Warming Emissions.

At the moment, there are no small reactors licensed by United State Nuclear Regulatory Agency (U.S.NRC or NRC). The only licensed reactors available for constructed in the United States are large plants from GE and Westinghouse. For details see our Nuclear Power Reactors page.

Analysis of Small Modular Reactors

We started researching Small Modular Reactors (SMR) when it became apparent that Washington politicians and utilities were becoming involved with the promotion and development of NuScale Power’s SMR. We quickly learned that three other SMRs were being promoted in similar ways in different parts of the country. We were concerned that these efforts would distract from our nation’s need to build hundreds of large plants needed to produce a serious reduction of our green house gas emissions.

One of our first research discoveries was an extensive list of frequently asked questions with answers on the NuScale website. Although prepared by NuScale it contained many entries applicable to SMRs in general. So we used it to guide our research on SMRs. The results of our research have been added as comments to NuScale’s Q&A’s and published as our SMR Q&A page. Our comments that are applicable to all SMR’s are also presented below.

We have spent much of the last three years researching everything from global warming to the causes of nuclear accidents in developing ENW’s view that for the next few centuries, nuclear power is only way to seriously cut our global warming emissions. The United States needs to build several hundred large nuclear plants in the next twenty years if we want to seriously reduce global warming emissions produced by generating electricity with fossil fuels. We would have to build over a thousand SMR modules the size NuScale proposes, to generate the same amount of power. Only if the “economy-of-small” proves to produce cheaper energy than the “economy-of-scale” would it make sense to install SMR’s in the continental United States.

Energize Northwest is very supportive of Nuclear Power and SMRs are an integral part of the Nuclear Renaissance. Our view is that companies promoting Small Modular Reactors should approach the development of SMRs not for use in the Lower 48 States, but for Hawaii and Alaska which have isolated locations with smaller power demands. But the largest market for SMRs is for export to island nations and developing countries that lack a large power grid.

With an internet search, we determined each Hawaiian Island’s current electrical generating capacity. Then we divided each island’s present megawatt capacity by 45 to determine the number of NuScale modules needed. Oahu would need 40 modules. Oahu has enough electrical demand to justify a large nuclear plant or two, but that would provide little flexibility or backup. Building pairs of 12-module NuScale plants at two different locations would provide better flexibility and operational security. Maui could start with a six-unit installation. The Big Island, Hawaii, needs seven units, Lanai, and Molokai would be overpowered with one unit each. All of the above islands are served by Hawaiian Electric Industries, Inc. Kauai is different as its electricity is provided by, consumer-owned, Kaua‘i Island Utility Cooperative. For now, it only needs the power from 3-modules. This might be an ideal location for NuScale’s first plant. We get the feeling from their 2013 Annual Report that they are a progressive organization, but more importantly, they are charging their customer-owners 36 cents per kilowatt-hour for electricity. Kauai would also be an ideal place to study the paradigm shift that will be caused by the introduction of SMRs to an isolated market with high electrical energy rates. When rates go down, demand goes up, and so will the demand for more modules. Even with its high electric rates, Kauai is going for electric vehicles. A June 25, 2012 posting on the Garden Island newspaper’s website announces that Kauai is only one of three places in the nation offering the fastest, Level 3 charging stations. It goes on to say that the Grand Hyatt in Po’ipu just added two Level 3 chargers to its existing Level 2 units and it is powering them with solar panels.

Another market for SMRs is powering ships. In our Converting Uses to Electric page, we suggest powering Washington’s Ferries with Nuclear Power. In 1955, President Dwight Eisenhower proposed building a nuclear-powered merchant ship as a showcase for his “Atoms for Peace” initiative. It only took seven years to go from a President’s idea to the sailing of Worlds first nuclear powered merchant ship, the N S. Savannah. We should be able to do better today.

An important feature of the original SMR concept is that the reactor would be supplied to the customer as a sealed unit, which would have to be returned to the manufacturer for refueling and disposal. Nuclear energy opponents have long held the valid concern that worldwide use of nuclear power could lead to misuse of the nuclear fuel. Nuclear proponents make the point that enriching uranium from commercial reactor fuel is about as difficult as doing it from raw uranium. However, there is little to stop a terrorist group, or rogue government, from making a dirty bomb by removing spent fuel rods from a plant’s cooling pond and strapping them to an explosive.

A sealed reactor module is a very plausible concept. The reactors that power our submarines and aircraft carriers are only somewhat larger that the module proposed by NuScale. Presently these reactors have a refueling cycle of over 20 years and engineers are well on their way to extending it to over 30 years. A commercial module, with a 25 year plus lifetime, could be assembled, fueled, and sealed at Hanford then shipped to a power plant anywhere in the world. Twenty five years later, the reactor can be returned to Hanford for decommissioning and disposal as have the 114 submarine reactors shown in this aerial photo taken in 2008.

(Burke first saw this site as he viewed it from his Hanford tour bus.)

Nuclear Submarine Reactors in Trench 94 At Hanford

Nuclear Submarine Reactors in Trench 94 At Hanford

However, a naval reactor is not the ideal pattern for a SMR to power a commercial ship. The naval reactors get their small size and long life because they use highly enriched uranium for fuel. Most commercial reactors’ uranium fuel is enriched to something less than 5%. Naval reactors are fueled with uranium enriched to over 80% U238. This would make it viable for bomb building. There are several reactors designs that derive more power from natural uranium or thorium but none of the four designs discussed here do.

If American developers want to market SMRs to the rest of the world, our government, and definitely our public, would not allow us to export power plants without sealing the reactor or having some absolute control over the plant. The real fear is that countries like China would make and sell SMRs without similar restrictions.

Small Modular Reactors

Below are the details about the four Small Modular Reactors in Pre-application Interactions with NRC. They are the NuScale, the B&W mPower, the Holtec160, and the Westinghouse SMR. We have listed them in order of electrical generating capacity, small to large. Note that all of these designs are “Paper Reactors.”

Paper Reactors, Real Reactors – Hyman G. Rickover (1953)

“It is incumbent on those in high places to make wise decisions and it is reasonable and important that the public be correctly informed. “An academic (paper) reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off-the-shelf components. (8) The reactor is in the study phase. It is not being built now.

“On the other hand, a practical (real) reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.”

Remember that these are only four of the 29 Small Nuclear Power Reactors listed in the World Nuclear Association’s (WNA) December, 2014 report. To view the entire 34 page report click here. Note in following summary from the WNA report, that the United States efforts include only nine of the 29 designs listed, and none of them are operating or under construction. All of ours are “Paper Reactors.”

  • Two reactors designs operating in Pakistan and India.
  • Three reactor designs under construction in Russia, Argentina, and China
  • Eleven reactor designs well advanced in development:  6 American but 2 are on hold, 3 Russian, and 1 each in China and Korea
  • Thirteen reactor designs in the early stages of development: 3 American, 3 Chinese, 2 each in Japan and Canada, and 1 each in France, India, and Russia

SMRs in Pre-application Interactions with NRC

NuScale SMR

From the U.S. NRC page on the NuScale SMR.

Project Overview

The staff of the U.S. Nuclear Regulatory Commission (NRC)NuScale is currently engaged in pre-application activities on the NuScale small modular reactor (SMR) design. NuScale is an integral pressurized-water reactor (iPWR), designed by NuScale Power, LLC. The design is based on MASLWR (Multi-Application Small Light Water Reactor) developed at Oregon State University in the early 2000s. NuScale is a natural circulation light water reactor with the reactor core and helical coil steam generator located in a common reactor vessel in a cylindrical steel containment. The reactor vessel/containment module is submerged in water in the reactor building safety related pool. The reactor building is located below grade. The reactor building is designed to hold 12 SMRs. Each NuScale SMR has a rated thermal output of 160 MWt and electrical output of 45 MWe, yielding a total capacity of 540 MWe for 12 SMRs.

For additional detail, see the following related pages:

NuScale Power website:

From World Nuclear Association’s (WNA) report on Small Nuclear Power Reactors (Updated Sept. 2014)

A smaller unit is the NuScale multi-application small reactor, a 160 MWt, 50 MWe integral PWR with natural circulation. In December 2013 the US Department of Energy (DOE) announced that it would support accelerated development of the design for early deployment on a 50-50 cost share basis. An agreement for $217 million over five years was signed in May 2014 by NuScale Power. It will be factory-built with 3-metre diameter pressure vessel and convection cooling, with the only moving parts being the control rod drives. It uses standard PWR fuel enriched to 4.95% in normal PWR fuel assemblies (but which are only 2 m long), with 24-month refueling cycle. Installed in a water-filled pool below ground level, the 4.6 m diameter, 22 m high cylindrical containment vessel module weighs 650 tonnes and contains the reactor with steam generator above it. A standard power plant would have 12 modules together giving about 600 MWe. An overhead crane would hoist each module from its pool to a separate part of the plant for refueling. Design life is 60 years. It has full passive cooling in operation and after shutdown for an indefinite period. The NuScale Power company was spun out of Oregon Sate University in 2007, though the original development was funded by the US Department of Energy. The company estimated in 2010 that overnight capital cost for a 12-module, 540 MWe NuScale plant would be about $4000 per kilowatt. After NuScale experienced problems in funding its development, Fluor Corporation paid over $30 million for 55% of NuScale in October 2011. With the support of Fluor, NuScale expects to bring its technology to market in a timely manner. The DOE sees this as a “near-term LWR design.” In August 2013 Rolls Royce joined the venture to support an application for DOE funding, and in March 2014 Enercon Services took undisclosed equity to become a partner and assist with design certification and COL applications. NuScale expects to lodge an application for US design certification late in 2016, and is already engaged with NRC, having spent some $130 million on licensing to November 2013. It expects the NRC review to take 39 months, so the first unit could be under construction in 2020. In March 2012 the US DOE signed an agreement with NuScale regarding constructing a demonstration unit at its Savannah River site in South Carolina. In mid-2013 NuScale launched the Western Initiative for Nuclear (WIN) – a broad, multi-western state collaboration* – to study the demonstration and deployment of a multi-module NuScale Small Modular Reactor (SMR) plant in the western USA. A NuScale SMR built as part of Project WIN is projected to be operational by 2024, likely in Idaho, followed by a second in Washington state. WIN includes Energy Northwest (ENW) in Washington and Utah Associated Municipal Power Systems (UAMPS). In mid-2014 the plan was for UAMPS to be the owner and ENW the operator of a plant built at DOE’s Idaho National Laboratory site. The UAMPS Carbon-Free Power Project will comprise a 540-600 MWe power plant (12 modules), costing $5000/kW on overnight basis, hence about $3.0 billion. Energy Northwest comprises 27 public utilities, and has examined small reactor possibilities before choosing NuScale.

* Washington, Oregon, Idaho, Wyoming, Utah and Arizona. 


B&W mPower™

From the U.S. NRC page on the B&W mPower SMR.

Project Overview

The staff of the U.S. Nuclear Regulatory Commission (NRC) is currently engaged in pre-application activities on the B&W mPower™ small modular reactor design. The B&W mPower™ is a light-water integral pressurized water reactor (iPWR) with the reactor and steam generator located in a single vessel located in an underground containment. The B&W mPower™ reactor has a rated thermal output of 530 MWt and electrical output of 180 MWe.

Pre-application interactions began in July 2009. On April 14, 2014, B&W announced the restructuring of its small modular reactors program to focus on mPower technology development. B&W’s press release may be found on their website at The date of tendering of a Design Certification application is to be determined.

In November 2012 the US Department of Energy (DOE) announced that it would support accelerated development of the design for early deployment, with up to $226 million in first round funding. However, most of the second round funding in 2013 went to NuScale, leaving leaving B&W short of funds to continue. In April 2014 B&W announced that it was cutting back funding on project to about $15 million per year, having failed to find customers or investors.

For additional detail, see the following related pages:

From World Nuclear Association’s (WNA) report on Small Nuclear Power Reactors (Updated Sept. 2014)

Babcock & Wilcox MPower In mid-2009, Babcock & Wilcox (B&W) announced its B&W mPower reactor, a 500 MWt, 180 MWe integral PWR designed to be factory-made and railed to the plant site. In November 2012 the US Department of Energy (DOE) announced that it would support accelerated development of the design for early deployment, with up to $226 million.

The reactor pressure vessel containing core of 2×2 metres and steam generator is thus only 3.6 metres diameter and 22 m high, and the whole unit 4.5 m diameter and 23 m high. It would be installed below ground level, have an air-cooled condenser giving 31% thermal efficiency, and passive safety systems. The power was originally 125 MWe, but as of mid-2012, 180 MWe is quoted when water-cooled. A 155 MWe air-cooled version is also planned. The integral steam generator is derived from marine designs, as is the control rod set-up. It has a “conventional core and standard fuel” (69 fuel assemblies, each standard 17×17, < 20 t)j enriched to almost 5%, with burnable poisons, to give a four-year operating cycle between refuelling, which will involve replacing the entire core as a single cartridge. Core power density is lower than in a large PWR, and burn-up is about 35 GWd/t. (B&W draws upon over 50 years experience in manufacturing nuclear propulsion systems for the US Navy, involving compact reactors with long core life.) A 60-year service life is envisaged, as sufficient used fuel storage would be built on site for this.

The mPower reactor is modular in the sense that each unit is a factory-made module and several units would be combined into a power station of any size, but most likely 360-720 MWe (2, 3 or 4 units) and using 250 MWe turbine generators (also shipped as complete modules), constructed in three years. B&W’s present manufacturing capability in North America can produce these units, and B&W Nuclear Energy Inc set up B&W Modular Nuclear Energy LLC (B&W MNE) to market the design, in collaboration with Bechtel which joined the project as an equity partner to design, licence and deploy it. B&W’s 90%-owned subsidiary, Generation mPower LLC (GmP), reports into B&W MNE. B&W expected both design certification and construction permit in 2018, and commercial operation of the first two units in 2022. Meanwhile the design is phase 1 of the Canadian Nuclear Safety Commission licensing process.

In November 2013 B&W said it would seek to bring in further equity partners by mid-2014 to take forward the licensing and construction of an initial plant.* B&W said it had invested $360 million in GmP with Bechtel, and wanted to sell up to 70% of its stake in the JV, leaving it with about 20% and Bechtel 10%. In April 2014 B&W announced that it was cutting back funding on project to about $15 million per year, having failed to find customers or investors. This will necessitate some renegotiation with DOE in respect to funding from that quarter, though about $101 million has already been paid. B&W planned to retain the rights to manufacture the reactor module and nuclear fuel for the mPower plant. In August 2014 the TVA said it would file an early site permit (ESP) application instead of a construction permit application for one or more small modular reactors at Clinch River, possibly by the end of 2015.

* When B&W launched the mPower design in 2009, it said that Tennessee Valley Authority (TVA) would begin the process of evaluating Clinch River at Oak Ridge as a potential lead site for the mPower reactor, and that a memorandum of understanding had been signed by B&W, TVA and a consortium of regional municipal and cooperative utilities to explore the construction of a small fleet of mPower reactors. It was later reported that the other signatories of the agreement were First Energy and Oglethorpe Power3. In February 2013 B&W signed an agreement with TVA to build up to four units at Clinch River, with design certification and construction permit application to be submitted to NRC in 2015. This intention has been superseded by the planned ESP application. In July 2012 B&W’s GmP signed a memorandum of understanding to study the potential deployment of B&W mPower reactors in FirstEnergy’s service territory stretching from Ohio through West Virginia and Pennsylvania to New Jersey.

Overnight cost for a twin-unit plant is put by B&W at about $5000/kW.


Holtec SMR-160

From the U.S. NRC page on the Holtec-SMR.

Project Overview

The staff of the U.S. Nuclear Regulatory Commission (NRC) is Holtec SMR-160currently engaged in pre-application activities on the Holtec SMR-160 design. The Holtec SMR-160 is a pressurized water reactor (PWR), designed by Holtec SMR, LLC with passive cooling. It is a light water reactor with the reactor, steam generator, and spent fuel pool located in containment. The reactor core is located below grade. The Holtec SMR-160 has a rated electrical output of 160 MWe.

For additional detail, see the following related pages:

From World Nuclear Association’s (WNA) report on Small Nuclear Power Reactors (Updated Sept. 2014)

Holtec International set up a subsidiary – SMR LLC – to commercialize a 140 MWe (446 MWt) factory-built reactor concept called Holtec Inherently Safe Modular Underground Reactor (HI-SMUR). The particular design being promoted is a 160 MWe version of this, SMR-160, with two external horizontal steam generators, using fuel similar to that in larger PWRs, including MOX. The 32 full-length fuel assemblies are in a fuel cartridge, which is loaded and unloaded as a single unit from the 31-metre high pressure vessel. Holtec claims a one-week refueling outage every 42 months. It has full passive cooling in operation and after shutdown for an indefinite period, and also a negative temperature coefficient so that it shuts down at high temperatures. The reactor will be offered with optional heat sink to atmosphere, using dry cooling. The whole reactor system will be installed below ground level, with used fuel storage. A 24-month construction period is envisaged for each $800 million unit ($5000/kW). Operational life claimed is 80 years.

Holtec expects to submit an application for design certification to NRC late in 2016. The detailed design phase is from August 2012, and it is apparently not as far ahead as the other three US small designs. The Shaw Group (CB&I subsidiary) is providing engineering support for the design, and in June 2013 URS Corporation joined to support design and qualification. Holtec expects its involvement to take a year off the development schedule. The Construction Permit Application and Preliminary Safety Analysis Report are due in June 2014.

In March 2012 the US DOE signed an agreement with Holtec regarding constructing a demonstration SMR-160 unit at its Savannah River site in South Carolina. NuHub, a South Carolina economic development project, and the state itself supported Holtec’s bid for DOE funding for the SMR-160, as did partners PSEG and SCE&G – which would operate the demonstration plant. Exelon, Entergy and FirstEnergy (though see above re mPower) were also supporters of the bid. Apart from the SCE&G demonstration plant, Holtec was negotiating to supply a SMR-160 to PSEG for its Hope Creek/Salem site in New Jersey, for which PSEG has sought an early site permit (ESP). After failing to get DOE funding, both PSEG and SCE&G reaffirmed their support for the SMR-160.



Westinghouse Small Modular Reactor (SMR)

From the U.S. NRC page on the Westinghouse Small Modular Reactor.

Project Overview

Westinghouse Small Modular Reactor (SMR)

The staff of the U.S. Nuclear Regulatory Commission (NRC) is currently engaged in pre-application activities on the Westinghouse SMR design. The Westinghouse SMR is an integral pressurized-water reactor (iPWR), designed by Westinghouse Electric Company with passive cooling. It is a light water reactor with the reactor and steam generator located in a single reactor vessel. The reactor building is located below grade. The Westinghouse SMR has a rated thermal output of 800 MWt and electrical output of 225 MWe.

For additional detail, see the following related pages:

In January 2014 Westinghouse announced that was suspending work on its small modular reactors in the light of inadequate prospects for multiple deployment. The company said that it could not justify the economics of its SMR without government subsidies, unless it could supply 30 to 50 of them. It was therefore delaying its plans, though small reactors remain on its agenda. (ENW)

From World Nuclear Association’s (WNA) report on Small Nuclear Power Reactors (Updated Sept. 2014)

This Small Modular Reactor is an 800 MWt/ 225 MWe class integral PWR with passive safety systems and reactor internals including fuel assemblies based closely on those in the AP1000 (89 assemblies 2.44m active length, <5% enrichment). The steam generator is above the core fed by 8 horizontally mounted axial-flow coolant pumps. The reactor vessel will be factory-made and shipped to site by rail, then installed below ground level in a containment vessel 9.8 m diameter and 27 m high. The reactor vessel module is 25 metres high and 3.5 metres diameter. It has a 24-month refueling cycle and 60-year service life. Passive safety means no operator intervention is required for 7 days in the event of an accident.

In May 2012 Westinghouse teamed up with General Dynamics Electric Boat to assist in the design and Burns & McDonnell to provide architectural and engineering support. A design certification application was expected by NRC in September 2013, but the company has stepped back from lodging one while it re-assesses the market for small reactors. The company has started fabricating prototype fuel assemblies. The DOE sees this as a “near-term LWR design.” In April 2012 Westinghouse set up a project with Ameren Missouri to seek DOE funds for developing the design, with a view to obtaining design certification and a combined construction and operation licence (COL) from the Nuclear Regulatory Commission for up to five SMRs at Ameren’s Callaway site, instead of an earlier proposed large EPR there. The initiative – NexStart SMR Alliance – had the support of other state utilities and the state governor, as well as Savannah River, Exelon and Dominion. However, this agreement expired about the end of 2013, and both companies stepped back from the project as DOE funds went to other SMR projects. In May 2013 Westinghouse announced that it would work with China’s State Nuclear Power Technology Corporation (SNPTC) to accelerate design development and licensing in the USA and China of its SMR. SNPTC would ensure that the Westinghouse SMR design met standards for licensing in China and would lead the licensing effort in that country. The status of this collaboration is uncertain. 

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