safety

The same industry that promised that nuclear power would be "too cheap to meter" is now touting another supposed cure-all for America's power needs:  the small modular reactor (SMR).  The small modular reactor is being pitched by the nuclear power industry as a sort of production-line auto alternative to hand-crafted sports car, with supposed cost savings from the "mass manufacturing" of modestly sized reactors that could be scattered across the United States on a relatively quick basis. The facts about SMRs are far less rosy. 

Proponents of nuclear power are advocating for the development of small modular reactors (SMRs) as the solution to the problems facing large reactors, particularly soaring costs, safety, and radioactive waste.  “Small modular reactors” are defined by the US Department of Energy (DOE) as reactors that would produce 300MWe or less and are made in modules that can be transported. Unfortunately, small-scale reactors can’t solve these problems, and would likely exacerbate them.

There has been a proliferation of proposed Small Modular Reactor designs, but none have applied for certification by the Nuclear Regulatory Com­mission (NRC) yet. The NRC says that it expects to receive its first SMR design certification appli­cation in 2012. The factsheet addresses SMR designs for which the NRC may receive design certification applications in FY2011. It does not include some designs that are being researched but that are not on the NRC list, notably the travelling wave reactor. IEER will produce a separate report later in 2010 on this reactor.

Inherently more expensive?
SMR proponents claim that small size will en­able mass manufacture in a factory, enabling considerable savings relative to field construc­tion and assembly that is typical of large reac­tors. In other words, modular reactors will be cheaper because they will be more like as­sembly line cars than hand-made Lamborghi­nis.

In the case of reactors, however, several offsetting factors will tend to neutralize this advantage and make the costs per kilowatt of small reactors higher than large reactors. First, in contrast to cars or smart phones or similar widgets, the materials cost per kilowatt of a reactor goes up as the size goes down. This is because the surface area per kilowatt of capacity, which dominates materi­als cost, goes up as reactor size is decreased. Similarly, the cost per kilowatt of secondary containment, as well as independent systems for control, instrumentation, and emergency management, increases as size decreases. Cost per kilowatt also increases if each reac­tor has dedicated and independent systems for control, instrumentation, and emergency management. For these reasons, the nuclear industry has been building larger and larger reactors in an effort to try to achieve economies of scale and make nuclear power economically competitive.

Proponents argue that because these nuclear projects would consist of several smaller reactor modules instead of one large reactor, the construction time will be shorter and therefore costs will be reduced. How­ever, this argument fails to take into account the implications of installing many reactor modules in a phased manner at one site, which is the proposed approach at least for the United States. In this case, a large contain­ment structure with a single control room would be built at the beginning of the project that could accommodate all the planned capacity at the site. The result would be that the first few units would be saddled with very high costs, while the later units would be less expensive.

The realization of economies of scale would depend on the construction period of the entire project, possibly over an even longer time span than present large-reactor projects. If the later-planned units are not built, for instance due to slower growth than anticipated, the earlier units would likely be more expensive than present reactors, just from the diseconomies of the containment, site preparation, instrumentation and control system expenditures. Alternatively, a contain­ment structure and instrumentation and control could be built for each reactor. This would greatly increase unit costs and per kilo­watt capital costs. Some designs (such as the PBMR) propose no secondary containment, but this would increase safety risks.

These cost increases are unlikely to be offset even if the entire reactor is manufac­tured at a central facility and some economies are achieved by mass manufacturing com­pared to large reactors assembled on site.

Furthermore, estimates of low prices must be regarded with skepticism due to the history of past cost escalations for nuclear reactors and the potential for cost increases due to require­ments arising in the process of NRC certifica­tion. Some SMR designers are proposing that no prototype be built and that the necessary licensing tests be simulated. Whatever the process, it will have to be rigorous to ensure safety, especially given the history of some of proposed designs.

The cost picture for sodium-cooled reac­tors is also rather grim. They have typically been much more expensive to build than light water reactors, which are currently estimated to cost between $6,000 and $10,000 per kilowatt in the US. The costs of the last three large breeder reactors have varied wild­ly.

In 2008 dollars, the cost of the Japanese Monju reactor (the most recent) was $27,600 per kilowatt (electrical); French Superphénix (start up in 1985) was $6,300; and the Fast Flux Test Facility (startup in 1980) at Hanford was $13,800. This gives an average cost per kilowatt in 2008 dollars of about $16,000, without taking into account the fact that cost escalation for nuclear reactors has been much faster than inflation. In other words, while there is no recent US experience with construction of sodium-cooled reactors, one can infer that (i) they are likely to be far more expensive than light water reactors, (ii) the financial risk of building them will be much greater than with light water reactors due to high variation in cost from one project to another and the high variation in capacity fac­tors that might be expected.

Even at the lower end of the capital costs, for Superphénix, the cost of power generation was extremely high — well over a dollar per kWh since it operated so little. Monju, despite being the most expensive has generated essentially no electricity since it was commissioned in 1994. There is no comparable experience with potassium-cooled reactors, but the chemi­cal and physical properties of potassium are similar to sodium.

Increased safety and proliferation problems
Mass manufacturing raises a host of new safety, quality, and licensing concerns that the NRC has yet to address. For instance, the NRC may have to devise and test new licensing and inspection procedures for the manufacturing facilities, including inspec­tions of welds and the like. There may have to be a process for recalls in case of major de­fects in mass-manufactured reactors, as there is with other mass-manufactured products from cars to hamburger meat. It is unclear how recalls would work, especially if transpor­tation offsite and prolonged work at a repair facility were required.

Some vendors, such as PBMR (Pty) Ltd. and Toshiba, are proposing to manufacture the reactors in foreign countries. In order to reduce costs, it is likely that manufacturing will move to countries with cheaper labor forces, such as China, where severe quality problems have arisen in many products from drywall to infant formula to rabies vaccine.

PBMR

Despite 50 years of research by many countries, including the United States, the the­oretical promise of the PBMR has not come to fruition. The technical problems encountered early on have yet to be resolved, or apparent­ly, even fully understood. PMBR proponents in the US have long pointed to the South African program as a model for the US. Ironically, the US Department of Energy is once again pursuing this design at the very moment that the South African government has pulled the plug on the program due to escalating costs and problems.

Other issues that will affect safety are NRC requirements for operating and security personnel, which have yet to be determined. To reduce operating costs, some SMR vendors are advocating lowering the number of staff in the control room so that one operator would be responsible for three modules. In addition, the SMR designers and potential op­erators are proposing to reduce the number of security staff, as well as the area that must be protected. NRC staff is looking to design­ers to incorporate security into the SMR de­signs, but this has yet to be done. Ultimately, reducing staff raises serious questions about whether there would be sufficient personnel to respond adequately to an accident.

Of the various types of proposed SMRs, liq­uid metal fast reactor designs pose particular safety concerns. Sodium leaks and fires have been a central problem — sodium explodes on contact with water and burns on contact with air. Sodium-potassium coolant, while it has the advantage of a lower melting point than sodium, presents even greater safety issues, because it is even more flammable than molten sodium alone. Sodium-cooled fast reactors have shown essentially no posi­tive learning curve (i.e., experience has not made them more reliable, safer, or cheaper).

The world’s first nuclear reactor to generate electricity, the EBR I in Idaho, was a sodium-potassium-cooled reactor that suffered a partial meltdown. EBR II, which was sodium-cooled reactor, operated reasonably well, but the first US commercial prototype, Fermi I in Michigan had a meltdown of two fuel assem­blies and, after four years of repair, a sodium explosion. The most recent commercial prototype, Monju in Japan, had a sodium fire 18 months after its commissioning in 1994, which resulted in it being shut down for over 14 years. The French Superphénix, the largest sodium-cooled reactor ever built, was designed to demonstrate commercialization. Instead, it operated at an average of less than 7 percent capacity factor over 14 years before being permanently shut.

In addition, the use of plutonium fuel or uranium enriched to levels as high as 20 percent — four to five times the typical enrichment level for present commercial light water reactors — presents serious proliferation risks, especially as some SMRs are proposed to be exported to developing countries with small grids and/or installed in remote locations. Security and safety will be more difficult to maintain in coun­tries with no or underdeveloped nuclear regulatory infrastructure and in isolated areas. Burying the reactor underground, as proposed for some designs, would not sufficiently address security because some access from above will still be needed and it could increase the environmental impact to groundwater, for example, in the event of an accident.

More complex waste problem
Proponents claim that with longer opera­tion on a single fuel charge and with less production of spent fuel per reactor, waste management would be simpler. In fact, spent fuel management for SMRs would be more complex, and therefore more expensive, because the waste would be located in many more sites. The infrastructure that we have for spent fuel management is geared toward light-water reactors at a limited number of sites. In some proposals, the reactor would be buried underground, making waste retrieval even more complicated and com­plicating retrieval of radioactive materials in the event of an accident. For instance, it is highly unlikely that a reactor contain­ing metallic sodium could be disposed of as a single entity, given the high reactivity of sodium with both air and water. Decom­missioning a sealed sodium- or potassium-cooled reactor could present far greater technical challenges and costs per kilowatt of capacity than faced by present-day above-ground reactors.

Not a climate solution
Efficiency and most renewable technologies are already cheaper than new large reactors. The long time — a decade or more — that it will take to certify SMRs will do little or noth­ing to help with the global warming problem and will actually complicate current efforts underway. For example, the current sched­ule for commercializing the above-ground sodium cooled reactor in Japan extends to 2050, making it irrelevant to addressing the climate problem. Relying on assurances that SMRs will be cheap is contrary to the experi­ence about economies of scale and is likely to waste time and money, while creating new safety and proliferation risks, as well as new waste disposal problems.

(This is a shortened version of the factsheet on Small Modular Reactors produced by Arjun Makhijani and Michelle Boyd for the Institute for Energy and Environmental Research (IEER) and Physicians for Social Responsibility (PSR), September 2010. It is available at: www.ieer.org/fctsheet/small-modular-reactors2010.pdf)

Contact: Leslie Anderson, +1 703 276-3256
Mail: landerson@hastingsgroup.com
Or: info@ieer.org

The process of increasing the licensed power level of a commercial nuclear power plant is called a “power uprate.” Power uprates are generally categorized based on the magnitude of the power increase and the methods used to achieve the increase. Currently a significant number of the nuclear power plants have plans for power uprate by larger or smaller amounts.

The increase in the electricity produced in a nuclear power plant can be achieved in two ways. One way of increasing the thermal output from a reactor is to increase the amount of fissile material in use. The amount of fissile material is increased either by increasing the degree of enrichment, or the density of the fuel. In boiling water reactors, the increased core power is achieved by increasing the core feed water flows and steam flows. In pressurized water reactors, the increased power outputs call for an increase either in the core coolant flows or in the main coolant temperature rise across the cores, or both.

In Japan, in February 2009 a working group on uprating was established within the Nuclear and Industrial Safety Subcommittee of the Advisory Committee for Natural Resources and Energy. The working group met on six occasions and released a report on March 2 this year.

The first reactor slated for uprating is Tokai No. 2 (BWR, 1100MW), owned by Japan Atomic Power Company (JAPCO). The company is likely to apply in 2011. According to JAPCO's management policy for the 2010 fiscal year, the plant will be uprated during a periodic inspection in the latter half of 2012. However, the other nuclear power companies do not appear to be very enthusiastic. Plans were supposed to be released during the 2009 fiscal year, but they have not appeared yet.

Method of uprating
Both the thermal and electrical output of Tokai No. 2 will be uprated by 5%. When completed the plant will have an electrical output of 1150MWe.

A 5% increase in electrical output will be produced by a 5% increase in the flow of steam to the turbines. The rate of revolution of the high-pressure turbine will be increased by replacing the stationary blades with blades with a wider flow-path surface area. It is said that this is the only change required.

To increase the flow of steam to the turbines by 5% it is necessary to raise the flow of water to the reactor core by 5%. To produce extra steam it is also necessary to increase the thermal output of the core. So as to avoid the need to make adjustments to the core, more new fuel assemblies will be loaded during periodic inspections. The average uranium-235 enrichment of the fuel assemblies is 3.7%. Although the output of individual fuel assemblies will not change, the total amount of fissile material in the core will increase, thus increasing thermal output overall.

It is said that this approach will raise output with the minimum of changes. There will be no need to make major modifications, or to increase the uranium enrichment. Nevertheless, many safety issues arise as a result of the increased supply of feedwater and steam generation.

Problems arising as a result of uprating
Safety-related problems include the following:

* The increased number of fission reactions will produce more radiation within the reactor building. Embrittlement of the pressure vessel due to neutron irradiation will proceed at a faster rate. This will reduce safety, especially if nuclear power plants are to be operated for 50 or 60 years.

* Replacing fuel at a faster rate will increase the amount of spent fuel. This will put extra stress on the cooling equipment of the spent fuel pools and will affect future treatment and disposal.

* Increased fission reactions will reduce the effectiveness of the control rods and reduce their life. They will have to be replaced more frequently. This will increase the volume of waste produced.

* The increased flow of steam will cause more wear and tear and hence exacerbate wall thinning of the steam tubes. There will also be more wear and tear on the turbine blades.

* The increased feedwater flow will place extra stress on the feedwater pump.

Another problem relates to cost. Although JAPCO has not said anything so far, it can be expected that costs will rise as a result of uprating. In the first place, a 7% increase in the rate of replacement of fuel assemblies results in only a 5% increase in electrical output. Add to this the increased rate of replacement of control rods and the increased wear and tear on pipes and turbine blades and one would expect costs to rise.

The Nuclear and Industrial Safety Subcommittee's report claims that there are "basically no safety problems", but it can be seen from the problems listed above that uprating reduces the safety margin. The chair of the working group tried to defend the uprating program on the grounds of "the needs of the people".

Uprating is one of many fronts on which Japan's nuclear safety is being whittled away. Others include extended operation cycles, life extensions for aging reactors and the use of MOX fuel in light water reactors. There is little sign so far that the Democratic Party led government will fulfil the pledge in its 2009 election Manifesto to place safety first in Japan's nuclear administration.

Source: Nuke Info Tokyo, May/June 2010 / IAEA; http://www.iaea.org/NuclearPower/PLIM-LTO/plim_DTG_power_uprating.html
Contact: CNIC, (Citizens' Nuclear Information Center), Akebonobashi Co-op 2F-B, 8-5 Sumiyoshi-cho, Shinjuku-ku, Tokyo, 162-0065, Japan.
Tel:  + 81-3-3357-3800
Mail: cnic@nifty.com
Web: http://cnic.jp/english/

On April 29, the European Commission released its Europeans and Nuclear Safety Eurobarometer report. The report attempts to measure EU citizen’s attitudes to nuclear power. It makes for very interesting reading indeed.

In the 2006 report, 62% of EU citizens people thought that nuclear power could help combat climate change. That number has plummeted to 46%. The number of people who answered ‘don’t know’ has risen in France, Spain, Finland, UK, Belgium, Luxemburg, Ireland, Estona, Lithuania, Poland, Czech Republic, Romania, Malta and Cyprus. France, UK and Finland are at the heart of the faltering nuclear ‘renaissance’.

• In Bulgaria, Germany, France and Romania the number of people who think nuclear reactors can be run safely has fallen. The number of EU citizens that want to increase nuclear in the energy mix increased from 14% in 2006 to 17% now but ‘Europeans still do not consider nuclear energy as an option to tackle the energy supply/use challenges faced by developed societies.’
• EU citizens ‘consider that the current share of nuclear energy in the energy mix should be maintained or reduced’. Not, you’ll notice, increase.
• ‘Lack of security to protect NPPs against terrorist attacks and the disposal and management of radioactive waste remain the major dangers associated with nuclear energy’
• 'Citizens would like to know more about radioactive waste management and environmental monitoring procedures.'

Bear this in mind, however. The report is produced against the background of the European Commission launching the European Nuclear Energy Forum (ENEF), in 2007. It is promoted as ‘a platform aiming to promote broad discussion, free of any taboos, on issues of transparency as well as the opportunities and risks of nuclear energy’.

So interested is the nuclear-industry dominated ENEF in ‘broad discussion’, breaking ‘taboos’ as well as discussing the ‘transparency‘, ‘opportunities’ and ‘risks’ of nuclear power that Friends of the Earth, Greenpeace and Sortir du Nucléaire pulled out of the body ‘accusing ENEF of stifling critical voices, ignoring their concerns and riding roughshod over alternative scientific evidence.’

(thanks to www.greenpeace.org)

The full report (6,6 MB) is available at: http://ec.europa.eu/energy/nuclear/safety/doc/2010_eurobarometer_safety.pdf

A large crack was discovered early in October 2009 in the outer containment wall of the Crystal River Nuclear Power Station during a scheduled refueling and maintenance outage. It is the latest in a series of alarming discoveries signaling the hidden deterioration in the “defense in depth” design concept of passive safety systems for US reactor containment structures which is very difficult, if not impossible, to catch by visual inspections.

A special inspection team from the United States Nuclear Regulatory Commission (NRC) was dispatched to the Crystal River on Florida’s west coast to look deeper into extent and root cause of the ½ inch (1.3 centimeters) wide horizontal crack that was discovered in the reactor’s 42-inch thick (106.7 centimeters) concrete containment wall. An official from the NRC estimated the crack to be at least 25-feet (7.62 meters) long. NRC’s Chairman Gregory Jaczko and Regional Director Luis Reyes made a tour of the cracked reactor on October 9 for a firsthand look.

Crystal River’s owner and operator, Progress Energy, reported the discovery to NRC on October 7, 2009 after maintenance workers began cutting a large hole through the concrete containment to provide passage for the removal and replacement of reactor’s worn steam generators. After cutting through the first 9-inches (22.9 centimeters) of the wall from the outside surface, workers found what was described as a “separation in the concrete” which is crisscrossed with steel reinforcing bars in the safety-related structure. The reinforced concrete containment shell is credited for safety by resisting and “containing” pressure-induced forces.

The Crystal River crack follows the April 2009 discovery of a hole that had corroded all the way through the steel inner liner of the containment system for the Westinghouse Pressurized Water Reactor at Beaver Valley station in Pennsylvania. The source of corrosion was determined to be a small piece of wet wood left behind from the original concrete pour decades earlier that bridged the inner wall of the concrete dome and the outer wall of the inner steel liner. The outer corrosion and through-wall hole was not discovered until a visual inspection found a blister in the paint on the inside of the reactor containment wall. When the paint and rust was removed, the inside wall of the concreted containment dome was visible through the hole. Similarly, NRC reports the same outside-to-inside corrosion-induced holes through inner steel liners for containments at the North Anna and Cook PWRs. The steel liner is credited for being leak tight to prevent the escape of radiation in the event of an accident.

In both cases, the deterioration in safety margins for the containment system components was not readily visible until the structure was compromised. The potential for the hidden convergence of corroded containment liners and cracks in containment walls is hard to ignore where it can be potentially revealed in the entire containment system failure during a nuclear accident.

The Crystal River reactor is a Babcock & Wilcox Pressurized Water Reactor similar in design to the notorious Three Mile Island Unit 2 that melted down in 1979 and the Davis-Besse reactor near Toledo, Ohio, which was discovered to be potentially weeks away from a core melt accident in 2002 due to leaking borated coolant corrosion that had eaten a deep cavity into the carbon steel head of the reactor pressure vessel. (see Nuclear Monitor 565, 22 March 2002: "Millimeters from disaster")

A NRC official was quoted to say “The discovery of this crack in the concrete does not appear to represent a major reduction in safety, and there are no immediate concerns because the plant is shut down.” The emphasis should be placed on the fact that the reactor is shut down. Progress Energy officials are now seeking to bring the reactor back on line by December 2009 but conceded that the outage might be extended depending on the findings and conclusions of the NRC special inspection. At present, neither the company nor the NRC were able to determine the cause of the crack or if it was present at the completion of the reactor construction 32 years ago. NRC did not know if the company would be required to fix the crack or allowed to bring the reactor back on line with the cracked containment. The NRC did acknowledge that it was looking into Crystal River’s crack for generic implications for reactors of similar design.

Crystal River’s has made application to NRC to extend its 40-year operating license by an additional 20 years.

Chief among public safety concerns voiced by nuclear power critics is whether or not more cracks are present and perhaps linked throughout containment and how containment integrity can be assured. Given that the crack was only discovered by workers destroying the containment wall to make a hole to replace the reactor’s steam generators, the watchdog community is eager to know how NRC and the industry plan to rule out further cracking and justify continued operations with uncertainty about any additional cracking in Crystal River and other PWR containments. The question arises whether or not an adequate analysis is even possible. One NRC containment specialist is quoted in an agency 2008 transcript to say, “It’s sort of difficult for us to do an independent analysis. It takes time. We’re not really set up to do it. The other thing you have to realize, too, for containment, which isn’t as true in the reactor systems area, is that we don’t have the capability.” In any case, the nuclear industry is likely to resist large scale non-destructive testing of its concrete containments to detect the presence of more cracking just as they have already resisted full scale ultrasonic testing measurements to determine remaining wall thickness on corroded steel liners in containments.

Beyond Nuclear, the public interest and safe energy group, has filed a request under the Freedom of Information Act for the release of documents and photographs regarding the Crystal River containment crack.

Source and contact: Paul Gunter, Director Reactor Oversight Project, Beyond Nuclear. 6930 Carroll Avenue Suite 400, Takoma Park, MD 20912.
Tel: +1 301 270 2209
Email: paul@beyondnuclear.org
Web: www.beyondnuclear.org