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Update on Small Modular Reactor Development

By Jim Hopf

The US Department of Energy has a $452 million program to share development and licensing costs for selected small modular reactor (SMR) designs. The DOE’s goal is to have an operating SMR by ~2022. Last November, the DOE awarded the first grant to the B&W mPowerTM reactor. In more recent news, the DOE has decided to issue a follow-on solicitation to enter a similar cost-sharing agreement with one or more other SMR vendors (and their SMR designs). The status of development and licensing for several SMR designs are summarized below.

mPower (B&W)

B&W mPower SMR

The mPower reactor is a 180-MW pressurized water reactor. B&W was awarded the first cost-sharing agreement under the DOE’s SMR development program in November 2012. B&W has teamed up with Bechtel and the Tennessee Valley Authority to design, license, and build a set of 2-6 mPower modules at TVA’s Clinch River site. B&W plans to submit its design certification application (DCA) to the Nuclear Regulatory Commission by the end of this year.


The NuScale reactor is an even smaller, 45-MW PWR reactor module. NuScale Power will apply for the follow-on (second round) DOE program cost-sharing award that was just announced. It has partnered with Fluor to develop and build the SMR, and is considering building its first SMR modules at the DOE Savannah River Site (SRS). It expects to submit its DCA to the NRC some time in 2015.


Holtec International, which is developing a 160-MW (light water) SMR, may also apply for the second DOE grant, and is also interested in constructing its SMR at the SRS site.


Westinghouse is developing a 225-MW PWR that shares many design features of its larger AP1000 plant. It is partnering with Burns & McDonnell, Electric Boat, and the Ameren utility to design, license, and build its first SMR plant at Ameren’s existing Callaway plant site in Missouri. It is expected to also apply for the second round of cost-sharing grants under the DOE’s SMR program. Westinghouse is expected to submit its DCA to the NRC in 2014.


The most advanced non-light water SMR project is the Gen4 Energy’s lead-bismuth-cooled 25-MW reactor module (formerly Hyperion). Given the DOE’s focus on near-term SMR deployment, however, and the NRC’s indication that licensing a non-LWR will take a much longer amount of time, it is unclear whether non-light water SMRs have much prospect for winning a cost-sharing award under the DOE’s current SMR development program. Gen4 Energy withdrew its application for the initial round of DOE grants and it is not clear if it will apply for the second round.

Key desirable SMR features

My personal view is that SMRs should (ideally) have the following three features, entirely or to the extent possible:

  • The entire nuclear steam supply system (NSSS) can be factory built and rail-shipped to site.
  • The reactor can go indefinitely without offsite power or forced (pumped) cooling.
  • No on-site construction subject to NQA-1 requirements.

In a recent ANS post, I discussed issues such as the basemat rebar (and other) problems at Vogtle, as an example of the problems that are likely to occur when there are a large number of construction activities that are subject to NQA-1 and NRC oversight being performed on site, often by local suppliers or craft labor that do not have extensive experience with nuclear-related construction. Processes are much more controlled in a factory setting, where one is simply making a large number of copies of the exact same product (reactor design). Also, the factory would have dedicated staff that is highly experienced in making copies of that one product, and is very experienced with the applicable nuclear-grade fabrication and quality assurance requirements (e.g., NQA-1). The result is much higher levels of quality and consistency, with much less in the way of cost overruns or schedule delays.

For these reasons, it is imperative to have as much of the safety/nuclear-related construction as possible be done at the factory, and to minimize assembly and construction activities at the plant site. Thus, it is very preferable to have the entire NSSS (reactor and steam supply system, e.g., steam generators) sealed inside a container that can be shipped by rail to the plant site, without any at-site assembly required. Ideally, all components necessary for safety would be inside the “box” that arrives on the rail car, resulting in only non-nuclear grade construction activities at the site.

In that recent ANS post, I suggested that due to spiraling nuclear plant construction costs, a bottoms-up review is in order, in which all regulations and requirements are put on the table and objectively evaluated (using detailed probabilistic risk analyses, etc.) in terms of how much “bang for the buck” we’re getting in terms of overall safety. I made the suggestion (provocative to many, I’m sure) that NQA-1, i.e., a unique and extremely strict set of fabrication/QA requirements that only applies to the nuclear industry, most likely does not produce much safety benefit relative to its associated cost. I suggested that more typical QA standards and procedures that are used in most other large construction projects (bridges, dams, etc.) be used instead.

Well, with SMRs a “compromise” may be possible. Based on recent experience with Areva’s EPR (at Olkiluoko) and now at Vogtle, I had come to doubt that it was possible or practical to comply with those NRC and NQA-1 requirements, with on-site plant construction anyway. It seemed to be too difficult to comply with such strict requirements under field conditions, especially given the use of local labor and suppliers that do not have extensive experience with those requirements. The factory assembly line setting, however, is one setting where I can imagine it being practical to comply with strict NRC/NQA-1 requirements (with highly experienced staff, a controlled process, and NRC inspectors permanently present at the factory site).

Thus, with SMRs, almost all important-to-safety fabrication is performed at the factory site, and it could still be held to NQA-1 standards. Onsite activities at the nuclear plant that are subject to NQA-1 requirements can be greatly reduced or perhaps (as part of a “compromise”) eliminated. In my view, not having onsite construction activities be subject to (nuclear-unique) NQA-1 requirements, and instead letting the local construction entities use more typical QA requirements that they are familiar with, would greatly reduce costs and the risks of schedule delays, rework, and cost overruns. On the other hand, having NQA-1 standards apply at the reactor module factory would deliver virtually all of NQA-1’s safety benefit, without significantly increasing costs.

Finally, it would be highly desirable for the plant to have the attribute of always remaining sufficiently cool to avoid meltdown for an indefinite period without any outside power or active cooling (pumps, etc.). Post-Fukushima, such a feature may greatly increase political and public support for the reactor design. Also, such a feature would greatly reduce the plausible conditions under which meltdown and release could possibly occur. This, in turn, could greatly reduce the number of components or systems that must be classified as “safety related”, which would result in significant cost reductions (as well as reductions in actual accident/release probability).

Features of SMR candidates

The main SMR candidates that meet the goals listed above are as follows, based on their publicly presented information:

The mPower and NuScale vendors state that their entire NSSS will be fabricated at the factory and shipped (whole) to the plant site. Westinghouse is less clear, referring to “rail shippable scale” (which could refer to the entire NSSS, or a small number of NSSS component modules, which would require a limited amount of on-site assembly).

Hauling the NuScale reactor

NuScale very clearly states that its SMR is entirely passively cooled, and can go indefinitely without outside power and active (pumped) cooling. B&W (mPower) is less clear on this point, stating that no AC power is required for design basis safety functions, that they have three-day batteries to support DC-powered accident mitigation, and that the station can go up to 14 days (under loss of power conditions) without outside intervention. Gen4 Energy also states that its (lead-bismuth) reactor can go 14 days without power. I could not find a statement from Westinghouse concerning how long its SMR can go without any external power. Westinghouse does make reference to the operator having to add water (to a large tank) after seven days.

As expected, none of the SMR vendors discuss fabrication QA requirements for at-plant-site construction and components, or how many such components would be classified as safety related. Some have, however, performed some PRA analyses and do discuss the very low probability of core damage and significant release for their reactors. B&W (mPower) and NuScale state that their core damage frequencies (CDFs) are 10-8 and 10-7 per reactor year, respectively. By comparison, currently operating plants generally have CDFs of ~10-4 per reactor year and more recent large plants (e.g., AP1000) have CDFs under 10-6.

Cost and safety tradeoffs

Due to their smaller size and lower power densities, SMRs offer inherent safety advantages, largely because smaller reactors are easier to keep cool. As shown above, their chances of core damage are far lower than those of large reactors. In addition to a lower probability of core damage, their much smaller fuel inventory greatly reduces the maximum possible release. In fact, since these reactors probably can’t get nearly as hot, even in a core damage scenario, I’m guessing that their maximum core inventory release fractions (e.g., for cesium) under even worst-case meltdown conditions are also significantly smaller than those that apply for larger reactors. Thus, the maximum possible release is probably even less than the ratio of reactor powers (MW) would imply.

In order to get these advantages (along with the advantages of assembly line construction), they have to give up on economy of scale and power density, which will tend to increase costs. Some SMR vendors claim that groups of their modules will produce less expensive power than large reactors (e.g., the AP1000), but this remains to be seen. It is also unclear whether these modular reactors will be less expensive than fossil fuels (particularly gas). As I’ve often stated, these reactors cannot provide any health, environmental, or global warming benefits if they are not deployed. Thus, some actions may need to be taken to reduce costs.

This leads me to ask what SMRs will “get in return” for what they are giving up in terms of scale, power density, and increased fundamental safety. We may have to ask if there are any measures that could be taken that would reduce costs but result in a release probability that is closer to that of, say, the AP1000, as opposed to being orders of magnitude lower. In these evaluations, the much lower potential release from these reactors should also be fully considered. I believe that thorough evaluations of all potential cost-saving measures, supported by detailed PRA evaluations, should be performed.

One idea I discussed earlier is to use ordinary construction QA requirements for all on-site construction activities (i.e., for everything outside the NSSS that arrives by rail car). Given the much lower likelihood of core damage/release, the much smaller potential releases, and the fact that components outside the NSSS have a relatively small impact on overall safety (especially for these reactors), such an approach would be justified. In evaluating such an approach, we need to make reasonable determinations of both the probability and possible nature of failures of non-nuclear-qualified components. For example, the NuScale reactors lay in a large pool of water inside a concrete-walled underground pit. We have to ask ourselves: Is there any way the concrete could fail that would result in the water disappearing (especially given that the pool is underground)?

Other issues are operator and security staffing levels. The simplicity and inherently better safety of these designs should reduce the number of required operators and staff (and some SMR vendors are claiming just that). Security costs could be greatly reduced (in my view) if SMRs are placed on existing sites where large reactors already exist. Little extra security should be required, since the site is already protected.

Also, as discussed in my earlier post, licensing review should be fairly limited if one is placing a certified SMR design on a site that already has reactors. Almost like spent fuel dry storage casks, a simple review of the existing site evaluations, to verify that external parameters such as maximum ground accelerations and other environmental factors are bounded by the SMR’s generic safety evaluations, should be sufficient. An evaluation of some bounding number of reactor modules would then be done to address any impacts of the reactors on the site (e.g., a site boundary dose evaluation). After that is done, modules could be added without further licensing activity.

The NRC’s general philosophies, however, as well as some of its recent actions, leads me to believe that any kind of compromise may be too much to expect. In response to Fukushima, the NRC is increasing nuclear regulations even further. While we all agree that some specific improvements can and should be made as a result of lessons learned from Fukushima, there has been absolutely no discussion at all about whether any requirements should be pared back. This, despite the fact that Fukushima showed that the consequences of a severe (almost worst-case) meltdown are FAR smaller than what we had thought (and far smaller than the assumed accident consequences that many if not most of those requirements were based upon). For this reason, I’m inclined to believe that the NRC will take all the benefits of SMRs (i.e., the great reduction in release probability due to fundamental features) and give absolutely nothing back. That, despite the fact that some economic sacrifices (on economy of scale) had to be made in order to get those fundamental increases in safety.

If SMRs are to be viable, and provide safety, health, environmental, and global warming benefits, the NRC is going to have to make some compromises. If they did, SMRs may be able to provide an option that is not only economically competitive (allowing it to displace harmful fossil fuels), but is also far safer than current US nuclear plants, and as safe or safer than new large plants such as the AP1000.


Jim Hopf is a senior nuclear engineer with more than 20 years of experience in shielding and criticality analysis and design for spent fuel dry storage and transportation systems. He has been involved in nuclear advocacy for 10+ years, and is a member of the ANS Public Information Committee. He is a regular contributor to the ANS Nuclear Cafe.

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Thank Joseph for the Post!

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wind smith's picture
wind smith on March 23, 2013

I would think the NQA-1 would be similar to the federal safety regulations that the commercial air transportation industry like Boeing works under.

Will all the design and engineering information/innovation be made public since all these SMR's are publicly funded?

Do you know what the expected thermal efficiency will be once the pumping, etc. loses are subtracted?

Also would be a big advantage to design in variable output capability from say 50% to 100% over a 24 hour period or even better over 1 hour. If so it could be used to back up renewables. If not can it really be integrated with renewables on the grid?

Where will run-in testing be done? I suppose the factory could have a permanent steam generator and turbine to test output and safety performance for qualification.  If this has to be done on site, the skill and oversight would need to be onsite during startup and debug.

Can the passive emergency shut down be tested at the factory? On site? Or is it even possible to test it at all because it would be a destructive test?

If put on existing nuclear plant sites for security reasons, will the resulting output from that site be increased by the SMR output? If so does the transmission exist to carry this extra? 

I can see how the reactor and primary coolant system can be shipped as an enclosed unit but not the steam generator.Doesn't the NSSS need to be connected to the steam generator on site? Would that not require the same reactor safety protocol as the factory built NSSS?

Seems like bringing the SMR's to market could be very risky. If all four of the companies in your article are competing for market share it may help get the customer (utilities) the best product for the lowest price. On the other hand if all decide to go to market it will dilute the amount of capitol available to tool up a factory for mass production. Since orders are likely to start out very slowly rather than the "large number of copies of the exact same product" they will not want to invest large sums of cash to tool up without a large number of orders on the books there by eliminating the lower cost of mass production. One or all of the competitors may be willing to build manually at substantially higher cost than mass production and sell at at loss for a while until the market shakes out. This is very risky and ,I think could bankrupt any one of them. I built special one of a kind machines for production of mass produced products for years. These machines ,though highly specialized,have far fewer parts both moving and otherwise than your standard automobile today. But because of the millions if not billions of dollars car companies spend on tooling for mass production they are 1/10th or less than the cost of a special machine. So I am well aware of the cost advantages of mass production just a little skeptical that SMR's can take advantage of it until the market grows massively - not at all guaranteed.

It looks like the NSSS units are sealed for life. If refueling is needed or any maintenance, I would think that would have to be done on site to NQA-1 standards which would not be available on site.

Michael Keller's picture
Michael Keller on March 23, 2013

Seems to me, the economics of the SMR are inherently noncompetitive, particularly when compared to the natural gas power plant. 

Consider combustion turbines. These machines are getting bigger and more efficient because that reduces production costs, thereby increasing profitability for the owners. Yet, the SMR goes in exactly the opposite direction.

Incidentally, there is another approach under development; a hybrid that marries the helium cooled, graphite moderated gas reactor and a combustion turbine. While technically a SMR (~600 MW thermal reactor), the plant is both efficient and powerful (+900 MW electric and 51% efficiency).   In other words, economies of scale are used to produce a very competitive power plant. Incidentally, the plant is fail-safe, which is a characteristic of the gas reactor originally developed by General Atomics.

The hybrid was, in fact, a candidate in last year’s DOE's SMR "contest" and Hybrid Power Technologies will again be in this year’s competition. While our firm is a small US business, we invented the hybrid-nuclear technology and hold the patent. Our website is   For those interested, we can forward papers/presentations made at various ASME conferences - see our website for contact information.

Nathan Wilson's picture
Nathan Wilson on March 23, 2013

"In order to get these advantages (along with the advantages of assembly line construction), they have to give up on economy of scale and power density, which will tend to increase costs. "

Maybe SMRs are the future of the nuclear industry, or maybe they will turn out to be 1) a beach-head in the nuclear renaisance, and 2) an entry level product for utilities and nations that are first time nuclear users.

SMRs are not the only way to gain the benefits of assembly line construction and integrating the reactor and steam generators.  The upper size limit of an SMR is determined by the maximum unit size that can be shipped by rail.  There are still many reactor sites in the world that can be accessed by sea, with no size limits.  Perhaps an unintended consequence of today's renewables boom will be a new willingness of utilities to put power generation resources further from end users (i.e. at location to which larger reactors can be shipped pre-assembled).

Or perhaps it's the size of the plant, and not the size of the reactor that drives the economics. Perhaps a 2-3 GW plant made from SMRs will be just as cheap as one built from two big reactors.  After all, the work force will be very experienced by the time the third or fourth module goes in.  Note that the mPower presentation linked above shows a fair cost improvement going from a 2-pack to a four pack.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 23, 2013

Factory production is one of the most attractive features of small reactors. But where will the nuclear waste go?

Will it remain onsite? Who will pay for onsite storage if that is the default solution.

Michael Keller's picture
Michael Keller on March 23, 2013

Observation on maneuvering an SMR: If the plant has poor economics at full power (and they do), reducing the load only makes the economics even worse. The plant's need to operate at high capacity factors to pay off the debt.

The daunting economics really hit home if you physically compare a 100 megawatt or so gas turbine to an equivalent SMR. The gas turbine is more or less bug dust on a relative size comparison.

I have no doubt the SMR's are safe; the fatal flaw is the economics.

Nathan Wilson's picture
Nathan Wilson on March 25, 2013

Yes, conventional natural gas plants are cheap.  Nuclear does compare well to other low carbon options however: coal or gas with carbon capture & sequestration, wind, geothermal, solar, etc.

Nathan Wilson's picture
Nathan Wilson on March 25, 2013

Electricity users pay $0.001/kWh for nuclear waste disposal (a tiny percentage, but one that is considered adequate for permanent underground disposal). Currently, the US government keeps the money and does nothing in return.  This has and will continue to lead to law suits.


On site waste storage actually works fine and is cost effective for essentially infinite duration! (thanks to the time value of money, a small cash set-aside provides enough interest to have the waste guarded and periodically repackaged, forever).  Centralized storage would save money, and required less diligence on the part of future generations, plus free-up what could be valuable real-estate.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 26, 2013

The onsite storage casks have not been licensed for an infinite storage period so eventually the nuclear waste will have to be transported to a permanent disposal site.

The U. S. government does not keep the money that ratepayers have put into the Nuclear Waste Fund. It spends this money for other programs. It owes money to the Nuclear Waste Fund. The same is true of Social Security money. In years that it collects more money than it issues to persons eligible for Social Security it spends rather than saves the excess funds.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 29, 2013

There is a great deal of competition for Department of Energy funds not only from various types of small reactors but also from operating reactors, spent fuel disposal, Hanford waste cleanup, renewable energy sources, conservation, grid expansion ,and a new supercomputer.

I K's picture
I K on March 26, 2013

If you can produce nuclear (or wind or solar) cheaply enough you can not only use it for 100% of your electricity but also for a large part of your process and space heating. 

Just using the UK as an example: We consume 330TWh of electricity and about 300TWh for “base load heat”.  If we switch this base load heat to electricity our electricity demand would be in the region 600TWh. VERY importantly this demand would be almost constant. 

An average 68GW not vary much under 60GW and not much over 80GW

We could build 65GW of nuclear to meet 95% of this electricity and base load heating. We would just need 10 nuclear power stations with 4EPRs each.

That would mean all our electricity and a lot of our heat was generated by nuclear. 

By comparison we can not do this with solar or wind. Solar is very limited in how far you can push it before the grid cant take anymore. You are looking at max in the region of 20% for the UK. Likewise you are looking at max 50% for wind in the UK.

That is quite a lot less than the 100% electricity and most of our base load heating that is achievable with a nuclear heavy approach

Paul O's picture
Paul O on March 26, 2013

I can't answer specifically where nuclear "Waste" from SMR will go, but I can say that I think you are asking the wrong question because:-

1) Nuclear "Waste" is not really waste. It is packed with unused nuclear power, unused only because of political decisions made as far back as the Jimmy Carter era, maybe even before that.

2) We have no  geological repository for nuclear "Waste" for political reasons, not because we can't find or build one.

IMO the proper question should be why don't we mandate the reprocessing of Nuclear "Waste", or require  that at least one Fast Reactor or MSR that uses "Waste" for fuel be built by companies that run Nuclear reactors.

Now AFAIK what's left behind after "Watse" has been through a Fast Reactor or a MSR, is much much smaller in volume and only requires sequestering for about 300yrs. There are monuments in the city of London that are older than that.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 26, 2013

If a fast reactor is required to handle the waste from a small modular reactor  it seems to me that this will increase the costs by quite a bit.

I agree that politics has delayed development of a permanent repository. I feel that licensing of the Yucca Mountain repository should proceed. I am not certain that it will be licensed, however, as there are concerns about volcanism, seismicity in the area and water infiltration of the repository. The latter may be compensated for by titanium drip shields. The titanium drip shields are very expensive. I have heard that the staff of the Nuclear Regulatory Commission feels that the Yucca Mountain repository is safe but the Nuclear Regulatory Commission can disagree with them. They sometimes take costs into consideration when ordering modifications of existing reactors.

Paul O's picture
Paul O on March 27, 2013

If we are talking strictly about the kind of reactor we should build, long term, I'd actually go for a fourth generation version of the SMR, either A Fast SMR, or A MSR like the LFTR.

Also bear in mind that The reason we don't have a Fast React or an LFTR today is....yeah you guessed it, POLITICS!

In any case, I am not worried about Volcanism because we know where volcanic areas are. Burying nuclear "Waste"  may be an added cost, but if it's amortized over the 60 yr life of the reactor and shared between the hundreds of reactors needed, it's a manageable cost.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 27, 2013

One must keep in mind that the amount of spent fuel produced is directly related to the amount of energy obtained. So if a SMF produces a small amount of spent fuel one will only get a small amount of energy from it.

wind smith's picture
wind smith on March 27, 2013

Take a 200mw SMR. The average community uses around 12,300 kwh/year-person. At 90% CP =  

15.7 x 10(8)kwh/year/12,300kwh/year-person = 128,000 people. About the size of a population center county in the midwest. If these residents decide that they would rather pay more for renewable with whatever backup they can get on the open market it's up to them not anybody else - that's politics.

There are some communities that may want to locate multiple SMR because of the property taxes or other local economic value - it's their political decision.

wind smith's picture
wind smith on March 27, 2013

Take a 200mw SMR. The average community uses around 12,300 kwh/year-person. At 90% CP =  

15.7 x 10(8)kwh/year/12,300kwh/year-person = 128,000 people. About the size of a population center county in the midwest. If these residents decide that they would rather pay more for renewable with whatever backup they can get on the open market it's up to them not anybody else - that's politics.

There are some communities that may want to locate multiple SMR because of the property taxes or other local economic value - it's their political decision.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 27, 2013

One can see a volcanic crater from the top of Yucca Mountain. I went on a tour of the Yucca Mountain repository and saw the crater. Geologists estimated that it was formed by an eruption 80,000 years ago.The Ubehebe Crater near Scotty's Castle in Death Valley, about 50 miles (by air) is estimated to have erupted about 6,000 years ago and there is evidence of more recent activity.

In 1992 there was a 5.6 magnitude earthquake  about a dozen miles from the  repository site. This has been interpreted as an aftershock of the 7.2 Landers earthquake. In 1999 there was a 4.7 earthquake 28 miles from the repository site. In 2002 there was a 4.4 earthquake 13 miles from the repository site.

Much of the money collected by ratepayers for a repository has been spent by congress.  The Blue Ribbon Commission on America's Nuclear Future did not come up with a plan for getting this money back.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 27, 2013

Communities cannot presently make the decision to site a reactor in their commnunity. A federal government agency, the EPA, sets radiation standards and another federal agency, the NRC, must license the reactor.The State of California has banned new reactors until there is a nuclear waste disposal facility. This has been upheld by the Supreme Court and other states are likely to use this decision if a community within a state wants to build a reactor but the state does not approve of this plan.

All this is something of a diversion from an excellent article by Hopf on Small Modular Reactors and comments on the desirable characteristics of a small modular reactor. To these physical characteristics I would also look at the record on cost overruns of companies applying for federal funds for a small modular reactor. History ignored is history repeated. I would also evaluate the assets of all companies applying for funding. Good plans usually can attract investors.

Paul O's picture
Paul O on March 27, 2013


Frankly I don't know why yucca mountain was sited, but there are such things as extinct valcanoes which due to plate tectonics have moved beyond the hotspot that originally birthed the volcanoe.

The reason this doesn't mean much to me in my support for nuclear power is that I prefer that support for Fast SMR, or MSRs which do not leave anything dagerous for more tham 300 yrs behind. And as I noted elsewhere, we have monuments sitting in London that are that vintage. We can surely site an underground cavern that will safely hold material for 300 yrs.

Nuclear power as it is today was the result of poor decisions from the Nixon, Carter, and Clinton years, where the LFTR, and Fast Reactors were sidelined for Reactors better suitted for bomb material, in Nixon's case, and  Carbon based fuel in Clinton's case. Carter was just afraid of things nuclear, AFAIK.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013

FOR PAUL O:  If you want to know more about the politics of siting Yucca Mountain I recommend articles by Matthew L.Wald in The New York Times.  Also, the Las Vegas Review Journal gives extensive  coverage of Yucca Mountain siting politics. The following books describe the politics of picking the Yucca Mountain site.

Stewart, Richard Burleson, Fuel Cycle To Nowhere: U. S. Law and Policy On Nuclear Waste, 2011.

Walker, J. Samuel, The Road to Yucca Mountain, 2009.

Robert Vandenbosch, Nuclear Waste Stalemate: Political and Scientific Controversies. 2007




Roger Faulkner's picture
Roger Faulkner on March 28, 2013

Where is the US Navy in all this? They have hundreds of small modular reactors running all over the world. Why not use these proven designs? And why not use them on board ships (or submarines)? Seems obvious to me, and could be quite a booming export business. HAVING REACTORS ON BOARD SHIPS WILL MAKE DECOMISSINING COSTS FAR MORE PREDICTABLE.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 28, 2013

How many ships will be needed to supply about 20% of our electricity? How many will be needed to eliminate U.S. contribution to global warming? Also, the nuclear powered ships use highly enriched plutonium and could become a target for entities that want to build nuclear weapon or just blackmail us.

I K's picture
I K on March 28, 2013

Surely everything can be built in the factory in one package, think of a nuclear submarine.

They have 1 or 2 small reactors producing in the region of 50MWe and the submarine is designed to be a war machine needing to house 100 people, missiles, torpedoes, propulsion, radar, sonar, armour, and god knows what else.... Instead think a dedicated power station in the package of a submarine.

Perhaps a quarter the the size and four times the power (since you dont need all that war stuff).

Built at a factory dock, towed to where it is required and connected to the grid.

The standardisation and factory production should make them considerably safer but imagine the worst happens and you lose control, well you could just toe the thing 300 miles in 10 hours to an uninhabited area and deal with it there rather than need to evacuate a million people within however many miles of a land based huge reactor.

Many advantages to these "floating small modular reactors"

Just to try and put a monetary value on this. Imagine a sub designed to be purely for power production rather than war with a 200MWe reactor. In Europe it would generate electricity worth about $130 million annually and supposedly nuclear sub reactors are designed with 40 year long as you could build such a 200MWe vessel for under $1B dollars you would sell as many as you could build. That doesnt sound a difficult price to hit imo especially considering you could probably sell ten thousand at that price.

I K's picture
I K on March 28, 2013

In Europe the average home uses 3MWh a year so a 200MWe SMR operating at 90% Capacity factor would produce the electricity energy consumed by 525,000 households.

That means just one of these reactors could power more than all the homes in Birmingham (the UKs second biggest city after London) which has a population of over 1 million people.

7 x 200MWe SMRs would be able to power all the homes in London (europes biggest city, about equal to New York City in population with 8.2m people)

I K's picture
I K on March 29, 2013

Assuming you can build a 200MWe submarine which was just a power plant not a war machine. 600 of these subs would be able to produce 1,000TWh of electricity which is about 25% of what the USA consumes. Or roughly the total electricity demand of Germany + Spain + UK

600 sounds like a lot but a submarine is very small and a submarine without the need for weapons, radar, armour, propulsion, missiles, and all the other war gear would be even smaller.

There is no reason you could not dock 20 of them at one shallow water location and run a cable a few hundred meters onshore. So you would only need 30 sites.  Also most sub reactors use uranium not plutonium.

Regarding them being a target for entities wanting to build nuclear bombs or blackmail you, don’t you think any group which is capable of stealing a propulsionless submarine and towing it a thousand miles undetected would probably be more than capable of buying or building one themselves?

I K's picture
I K on March 29, 2013

Consider combustion turbines. These machines are getting bigger and more efficient because that reduces production costs, thereby increasing profitability for the owners. Yet, the SMR goes in exactly the opposite direction.

That is a bold statement, how do you know when no SMRs for electricity generation have been produced?

Also from an engineering standpoint, a modern gas CCGT power station is more complex and pushes the limits of materials more than a nuclear reactor does. Afterall, we built nuclear reactors 60 years ago but its only been about 15 years since we have had the technology and materials capable of withstanding the very high temperatures of modern CCGTs.

There is no reason SMRs could not be mass produced at very competitive prices
Think of large aeroplanes, mass produced in the thousands and again their engines are in many ways a lot more complex and work at higher temperatures and material limits than a SMR would.

The only real problem is that the west turned its back on nuclear 30 years ago and the east was/is too poor to build any

Roger Faulkner's picture
Roger Faulkner on March 29, 2013

I would add that counting on the US Navy for security would make me feel much safer than Homeland Security or private companies reporting to multiple agencies. It is intrinsically more difficult to board a submarine than to breach security on a ship or a land-based reactor. There are also some more subtle advantages as well (but these advanced technology options do not have the property of relying on the proven Navy nuclear reactor design): the most efficient type of reactor is the high temperature gas cooled reactor (HTGR) which uses helium as both core coolant and working fluid. (Helium-4 is the ONLY isotope that will not react with neutrons and so CANNOT become radioactive.) A big part of the cost of such a reactor is the pressure vessel around the core (this is always true, but higher pressures are used for HTGRs). By placing a submersible reactor at a depth where the water pressure equals the core pressure, the cost of the core pressure vessel could be reduced. Also, siting reactors in submarines makes it possible to generate intentional upwelling of deep ocean waters as a byproduct of cooling, which will enhance local ocean fertility (places where there is natural upwelling are known to produce much better fishing).

I would not recommend placing reactor submarines in particularly shallow water for this reason: the base of surface waves goes about ten times as deep as the surface disturbance. Because of this, I’d be in favor of the power reactor subs being placed around 300-500 feet deep. And, I would like to see them remain under the control of the US Navy at all times. This scenario could be scaled up to full commercial scale faster than any other option.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 29, 2013

For Roger Faulkner ( March 29 post):                                                                                                     

There is no way to guarantee that the U. S. Navy can control your submarine reactors for all time. First one has to consider international law which limits how far out in  the ocean the U.S. has control. The Department of Defense assigns responibilities within the Department and the U.S. Navy presently is only one of the Departments of the Department of Defense. Furthermore future congresses can change the responsibilities  of the Department of Defense and the Navy by law and on a year to year basis through the appropiations process.

Again, like many advocates of small reactors and other nuclear reactors, you neglect to mention plans for disposal  of the nuclear waste produced by these reactors.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013


                                                                                                                                                                          I am skeptical of the claim that spent fuel rods from small modular reactors have little radioactivity after 24 months. Can you provide some numbers? Cs-137, one of the most troublesome fission products, has a half-life of 30 years.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013

Actually Navy ships use highly enriched uranium. The reactors produce Plutonium. They used to reprocess naval spent fuel in Idaho. The leftovers from reprocessing still require eventual disposal in a repository.The plan was to dispose of waste from Navy nuclear reactors at Yucca Mountain. Failure to implement this plan leaves naval nuclear reactor waste stranded.  The Blue Ribbon Commission on America’s Nuclear Future in 2012 recommended that another disposal site be developed PROMPTLY. The Department of Energy recently announced a plan to have a disposal facility available in 2048.

I suspect that some people who are interested in SMR’s are disinterested in nuclear waste management because they do not want to include disposal costs in the costs for SMR’s. 

wind smith's picture
wind smith on March 30, 2013

Jim, one of the biggest questions I have for a professional like yourself is about the build out of nuclear either large or SMR’s and it’s return on investment. The power market is getting more deregulated,decentralized and competitive every year. I realize the limited monopoly that most utilities have in their areas due to state or federal laws and the transmission they own, but like the story about NRG below it just adds more risk to massive projects like nuclear. Even nuclear owned by a utility or a wholesaler getting a 20 to 60 year PPA, the final customer, as technology develops and disrupts business models, will take the least cost option leaving the nuclear investors with lower and lower returns or customers without choice higher and higher rates.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013

FOR PAUL O (March 26)

The moratorium on reprocessing was ended during the Reagan administration but has not been resumed largely because of economics. Many feel. it is less expensive in the U. S. to dispose of the spent fuel than to reprocess it. This depends on the price of Uranium and the costs of reprocessing. France does reprocessing but the government subsidsizes  it. Another drawback is that France has produced a large amount of Plutonium which presents a proliferation risk. Some efforts are being made to convert the Plutonium into MOX fuel which can be used in reactors. The UK, Japan and some other countries also use reprocessing.


Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013

How frequently do volcanoes move? Can one predict the direction  of their move?

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013

A submarine that is not mobile would make a good target for terrorists but admitedly less likely to be captured by blackmailers except off the east coast of Africa.

I K's picture
I K on March 30, 2013

There is no need to make nuclear more efficient than 38%, there is a need to make them cheaper and safer and the SMR factory produced reactors may achieve that.

Regarding CCGTs yes they are fantastic they achieve 60% and they may go towards 65% but there is a limit. If higher temperature materials can be developed who knows maybe they can hit 70% that would be fantastic!

Contrary to what you are suggesting there have been advances in steam generation. Super critical plants have pushed steam efficiency over 45% mark and if new materials can be developed to withstand higher pressures that figure will rise.

Susanne Vandenbosch's picture
Susanne Vandenbosch on March 30, 2013

The Plutonium produced in enriched uranium fueled reactors does not need to be enriched to produce bomb material. It is easy to separate this Plutonium from the Uranium spent fuel and from fission products and therefore there  is a proliferation risk. It would be more difficult to try to make a bomb from the Uranium in the spent fuel because to get enough fissionable material enrichment of fissionable Uranium isotopes would have to be done. This is much more difficult.

I agree that it could not be done in a garage but unfortunately some terrorist entities ( a state or an interest group) have access to facilities that can isolate plutonium.



I K's picture
I K on March 31, 2013

You are double accounting

Think of it this way, instead of using your reactor to compress air for the CCGT, how about you use a CCGT to compress air for the CCGT? Then you can claim the second CCGT is 80% efficient while ignoring that the first one is only 40%….


wind smith's picture
wind smith on March 31, 2013

True, but we need to have a true accounting for items like public health costs due to air and water quality, loss of wildlife habitat or agricultural land due to emissions including CO2. Like public roads or national defense, power is more difficult to run under a free market system. Our local electric cooperative is putting a higher and higher fixed cost charge which is independent of power consumption to maintain the 4000 miles of transmission line. At some point PV with storage may be a cheaper way to go.

Roger Faulkner's picture
Roger Faulkner on April 1, 2013

Disposal remains an issue, and a real one. But to put it in perspective, nuclear power has caused far less harm than coal has, for example. And as to the longebvity of pollution, i think bio-accumulating heavy metals like lead and mercury have longer half-lives in the biosphere than a million years, worse than radioactive wastes which are compact and capable of being stored or transmuted (in the case of the transuranics). I certainly would not envision these reactors moving about, they would plug in and work for 20 years or more, but could return to base for major retrofits or decommisioning. I would not propose putting the reactors far offshore. The primary reason to place them in submarine hulls rather than surface ships would be to protect them from storms and collisions.

Mike Keller: Thanks for those clarifications. I was deeply into nuclear energy 40 years ago, but have not kept up to date. I did not realize that the sub fleet uses highly enriched uranium. I certainly would not allow sea water to contact the core, and I get it that a modular HTGR would be challenging; this is an R&D concept that I should not have mixed with this post, which is about using all that Navy reactor development to move SMRs forward faster than is happening today. Actually, I think the thorium to uranium 233 “break-even breeder” power cycle is interesting, and that could fit inside a pressure hull according to R&D by General Atomics.

In fact, I do not consider myself pro-nuclear, but it looks to me that the current crop of reactors is a lot dirtier than it needs to be, and decommisioning will be extremely difficult and expensive. Small modular reactors are part of a potential solution, and putting them under military protection in a transportable format makes them more practical i think.

I K's picture
I K on April 1, 2013

Whatever you use you can’t get away from the hundred year old equation

Efficiency = 1 – (Tc/Th)

which tells you that to hit anywhere near 80% efficiency you are looking at an inlet temp in excess of 2,500-3,000 Kelvin which is unlikely as the best in class CCGTs max out around 2,000 Kelvin

Doesn’t matter if you are using a hybrid design or unicorns you cant claim >80% efficiency without claiming >2,500 Kelvin temperatures….or at least claiming you broken the known laws of thermodynamics? Not very likely.

Mr. Edo's picture
Mr. Edo on April 6, 2013


Factory production of small modular reactors is a recipe for disaster.

How many car companies have recalls due to factory production of parts.

The last thing you want with anything to do with nuclear is a cookie-cutting, cost-saving measures.

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