Chapter 4 of reference [9.14] explains “license-by-test” approach as follows:

A reactor prototype could be built and subjected to a pre-agreed set of anticipated transient without scram (ATWS) and other accident initiators. By demonstrating safety based on passive response, on the prototype, the licensing authority might be able to certify the design, permitting the manufacture of many tens (or hundreds) of replicate plants to the set of prints and design specifications used for the prototype. In order to assure that aging effects do not degrade the passive safety features of deployed plants, the licensing authority could prescribe the performance of periodic in-situ tests on the plant to confirm continued presence of reactivity feedbacks in the required range and of passive decay heat removal continuously operating at the required rate.

Application of such approach may be useful for licensing of the small reactors with long operation cycle, for which:

• it would be difficult to obtain the immediate licence for a long (15-30 years) operation cycle;

• mass production of standardised reactor modules is foreseen.

An example of the regulatory framework for the license-by-test approach is provided by the US NRC regulation 10 CFR Part 52 “Early site permits; standard design certifications; and combined licenses for nuclear power plants” [9.15]. Part B of this document refers to “…acceptable testing of an appropriately sited, full-size prototype of the design over a sufficient range of normal operating conditions, transient conditions, and specified accident sequences, including equilibrium core conditions.”. So far, there have been no applications proposing license-by-test under 10 CFR Part 52. However, very similar approach has been used in licensing of the non-commercial Experimental Breeder Reactor — II (EBR-II) built and operated in the Argonne National Laboratory (ANL, United States) in the 70-90s [9.16].

The present NEA study is a synthesis report on the development status and deployment potential of SMRs. It brings together the information provided in a variety of recent publications in this field, and presents the characterisation of SMRs already available for deployment and those that are expected to become available in the next 10-15 years. It also highlights the safety features and licensing issues regarding such reactors.

Particular attention is paid to the economics of SMRs, and various factors affecting their competitiveness are analysed and discussed. Vendors’ data on the economics of different designs are compared with independent quantitative estimates of costs of generating electricity, and the deployment potential of such reactors in a number of markets and geographic locations is analyzed.

Currently, there are two definitions of such reactors widely used in the literature: Small and Medium-sized Reactors and Small and Modular Reactors. The same abbreviation is used — SMRs. Small and modular reactors have attracted much attention since 2008 when several very small reactors (less than 125 MWe) were announced in the United States. Since these reactors are a sub-class of the wider definition — Small and Medium-sized Reactors — in this paper we consider the general case of reactors with the effective electric power less than 700 MWe. However, the main focus in this report is on small reactors i. e. reactors with less than 300 MWe.

SMRs have been on the agenda since the early days of nuclear power. Historically, all reactors at that time were of smaller size compared to those deployed today[9], but the general trend has always been toward larger unit sizes (with lower specific costs due to the economy of scale), resulting in nuclear power plants with reactors of 1 000-1 600 MWe being most commonly commercialised today.

However, starting from the mid-1980s, a new set of requirements have motivated the development of intentionally smaller reactors in some countries aimed at the niche markets that cannot accommodate NPPs with large reactors. The main arguments advanced in favour of SMRs are:

• Because of their size, the upfront capital investment for one unit is significantly smaller than for a large reactor, and there is flexibility for increasing capacity. This reduces financial risks and could potentially increase the attractiveness of nuclear power to private investors and utilities.

• Smaller nuclear reactors could represent an opportunity to develop new markets for nuclear power plants. In particular SMRs could be suitable for areas with small electrical grids and for remote locations or, alternatively, in countries with insufficiently developed electrical infrastructure.

• SMRs often offer a variety of non-electrical energy products (heat, desalinated water, process steam, or advanced energy carriers) via operation in a co-generation mode[10].

Because of these arguments, there are currently about a dozen new SMR designs reaching advanced development stages, with one plant (a barge-mounted co-generation plant with two ice-breaker type KLT-40S reactors) currently under construction in the Russian Federation, three more in a formal licensing process in Argentina, China, and the Republic of Korea, and several others being under pre-licensing negotiations in the United States and India.

On the other hand, there are some issues regarding the viability of advanced SMRs, namely:

• A question on the economic competitiveness of SMRs, especially the higher specific construction cost of SMRs with respect to larger reactors.

• Potential concerns about the possibility of SMRs being sited in close proximity to end-users, based on the current regulatory norms and practices established to support the deployment of NPPs with large reactors.

• Legal and institutional issues regarding the possibility of international transport of NPPs with factory fabricated and fuelled reactors (a distinct group of advanced SMR designs) from one country for deployment in another.

The present study discusses these issues with a focus on the economic aspects and the competitiveness of a NPP with SMRs, in comparison to large reactors and non-nuclear technologies.

The main primary source of electricity in China is coal (more than 78%). The remaining part in 2008 was shared between hydropower (about 17%) and nuclear power (about 2%), see Figure 7.6.

In the case of China the costs of generating electricity at coal-fired and gas-fired power plants are so low (without carbon pricing) that neither SMRs nor state-of-the-art large reactors can currently compete (neither at a 5% nor at a 10% discount rate). However, nuclear power plants are currently being intensively built in China, showing that the economic factors are not the only ones in decision making.

In the Chinese case, small reactors could be competitive only with renewable plants (onshore wind, solar).

A principal conclusion of this study is that SMRs have a significant potential to expand the peaceful applications of nuclear power by catering to the energy needs of those market segments that cannot be served by conventional NPPs with large reactors. Such segments could be:

• Niche applications in remote or isolated areas where large generating capacities are not needed, the electrical grids are poorly developed or absent, and where the non-electrical products (such as heat or desalinated water) are as important as the electricity;

• Replacement for the decommissioned small and medium-sized fossil fuel plants, as well as an alternative to newly planned such plants, in the cases when certain siting restrictions exist, such as limited free capacity of the grid, limited spinning reserve, and/or limited supply of water for cooling towers of a power plant;

• Replacement for those decommissioned fossil-fuelled combined heat and power plants, where the SMR power range seems to better fit the requirements of the currently existing heat distribution infrastructure;

• Power plants in liberalised energy markets or those owned by private investors or utilities for whom small upfront capital investments, short on-site construction time (with the accordingly reduced cost of financing), and flexibility in plant configuration and applications matter more than the levelised unit electricity cost.

It should be noted, however, that none of the smaller reactors has yet been licensed for these applications and there remain both development challenges to overcome and regulatory approvals to obtain before deployment, especially in light of the recent accident at Fukushima.

The present study has found no situations where NPPs with SMRs could compete with the NPPs with state-of-the-art large reactors, on LUEC basis. However, it also found that SMRs could be competitive with many non-nuclear technologies in the cases when NPPs with large reactors are, for whatever reason, unable to compete.

[1] Levelised unit cost of electricity (LUEC) is calculated using the discounted cash flow method over the whole lifetime of the plant, and includes the initial investment, operations and maintenance, cost of fuel, financing and decommissioning costs. LUEC is measured in the units of currency per units of energy (e. g. in USD per MWh).

[2] Design simplification. In some advanced SMRs, significant design simplifications could be achieved through broader incorporation of size-specific inherent safety features that would not be possible for large reactors. If such simplifications are achieved, this would make a positive contribution to the competitiveness of SMRs. The vendors estimate that design simplification could reduce capital costs for near-term pressurised water SMRs by at least 15%.

[3] In order to arrive at a heat credit per MWh of electricity, one needs to establish the total value of the heat produced over the lifetime of the plant by multiplying total heat output by its per unit value. The total value of the heat output is then divided by the lifetime electricity production to obtain the per MWh heat credit. For plants operated in a co-generation mode, a heat credit is then subtracted from total unit costs to establish an equivalent of the levelised costs of producing only electricity.

16

[4] The parameter n of the scaling law is not known precisely. Based on reported values and analysis, an interval of n=0.4-0.6 has been considered in the calculations. For example, if the size of the unit is decreased by a factor of 2, the capital cost would decrease only by 25-35%. That would result in an increase of the specific capital cost by a factor 1.3-1.5.

[5] In Brazil, more that 70% of electricity is generated from the hydroelectric power plants offering very low cost electricity. Other sources of electricity, including nuclear power plants (with large reactors or SMRs), have higher electricity generation costs.

[6] *90 MWe (Korea) W 2*35 MWe, barge (Russia)

2*8 MWe, barge (Russia)

[7] According to the vendors and designers, all the advanced SMRs listed in Table 1 have been designed or are being designed in compliance with their current national regulations.

[8] Replacement for the decommissioned small and medium-sized fossil fuel plants, as well as an alternative to newly planned such plants, in the cases when certain siting restrictions exist, such as limited free capacity of the grid, limited spinning reserve, and/or limited supply of water for cooling towers of a power plant;

[9] SMRs constitute an important share of the actual nuclear fleet: 136 of the 441 reactors in operation, mostly those of older design, have a power falling in the SMR range [1.1]. In 2010, nine nuclear power plants under construction were SMRs [1.1].

[10] It is important to underline that co-generation is not unique to SMRs. However, as will be discussed later, the SMR power range corresponds well to the infrastructure requirements for non-electrical products (e. g. district heating).

[11] Taking into account non-electrical applications.

[12] The detailed design specifications for SMRs shown in Table 3.1 are given in Table A1.1 of Appendix 1.

[13] The detailed design specifications for SMRs in Table 4.1 are given in Tables A1.2 (a) and (b) of Appendix 1.

[14] Safety implications of the features of the above mentioned design groups are discussed in Section 8.2.

[15] Late in 2010 the Westinghouse Electric Company stopped the development of the IRIS project and announced it would go with an alternative integral design PWR of a 200 MWe class. Very few technical details of this new SMR were available as of June 2011.

[16] IMR is the only PWR design in which coolant boiling is allowed in upper part of the core [4.1]. Boiling boosts natural convection and makes it possible to use natural circulation of the primary coolant in normal operation, at a relatively high power level of 1 000 MWth (350 MWe).

[17] The projected construction period for advanced SMRs (typically two to five years for PWR SMRs) is typically shorter than the time needed to build SMRs available today.

[18] See the last row in Tables A1.2(a) and (b) of Appendix 1.

41

[19] The detailed design specifications for BWR SMRs are given in Table A1.3 of Appendix 1.

[20] Safety implications of BWR SMRs are further discussed in section 8.3.

[21] Recent deployments of the ABWR in Japan were accomplished with a three-year construction period [4.4].

[22] Including one atypical, dated-design pressure vessel type HWR in Argentina.

[23] The design specifications for the AHWR are given in Table A1.4 of Appendix 1.

[24] An option to increase AHWR unit power up to 500 MWe is being discussed.

[25] The design specifications for these reactors are provided in Table A1.5 of Appendix 1.

[26] All HTGRs provide for concentrated deployment with multi-module plants, although distributed deployment is not excluded for the ‘pin-in-block’ GTHTR300 and GT-MHR.

• The operating helium pressure is between 7 and 9 MPa, with 7 MPa being the preference.

• The average fuel burn-up is between 80 and 120 MWday/kg, being the maximum for the ‘pin-in-block’ designs.

[27] The detailed design specifications of the 4S are provided in Table A1.6 of Appendix 1.

[28] Seven Alfa class submarines (powered with 155 MWth lead-bismuth cooled reactors BM-40A) were in service from 1972 till 1990.

[29] The technology was developed for non-fast spectrum lead-bismuth cooled reactor cores. Applicability of this technology to fast spectrum cores may need additional validations.

[30] The corresponding detailed design specifications are provided in Table A1.7 of Appendix 1.

[31] For the New Hyperion Power module the date of a formal licensing application is still not defined, while licensing pre-application is already in progress.

[32] http://www. powergenworldwide. com/index/display/articledisplay/3386201290/articles/cogeneration-and-on- site-power-production/volume-n/issue-3/features/carbon-free-nuclear. html

[33] http://www. vnipiep. ru/dalnee_teplosnabzhenie. html

[34] http://bilnpp. rosenergoatom. ru/eng/about/info/

[35] For example, the EC6 (see Section 3) has a proven capability of daily load cycles from 100% to 60% of rated power, and can continue operation with loss of line to grid [4.41]. Some of the currently operated large French reactors (e. g. REP-1300 MWe, N4 design of 1 450 MWe) use daily cycles from 100% to 40% of rated power. Moreover, both the EPRI Utility Requirements Document and the European Utility Requirements (EUR) stipulate that the reactors should be capable of daily load cycles from 100% to 50% (or even 20%) of rated power [4.43].

[36] The reactor power level in the 4S is changed only by adjusting the steam flow rate in the power circuit. In this, the electric power dispatched to the grid and the steam flow rate in the power circuit are controlled in an active mode.

[37] From the condition that an unplanned NPP shutdown does not disrupt the stable grid operation.

[38] Simplified decommissioning limited to disconnection and removal of the transportable modules.

[39] However, three attributes that distinguish most of the new US small and modular reactors from other small reactor concepts developed elsewhere in the world, are namely:

— multi-module plant option;

— option of flexible capacity addition/removal; and

— underground reactor modules.

[40] Some recently announced concepts of small fast reactors for waste incineration, such as the fast-spectrum gas cooled EM2 of 240 MWe (being proposed by the General Atomics in the United States [5.7]), abandon fuel reprocessing and suggest that the spent fuel could be stored within the disconnected reactor module on the site or in a repository.

[41] In [6.1], a term LCOE — levelised cost of electricity is used. We use another abbreviation — LUEC — that is equivalent to LCOE, to be consistent with the literature on SMRs.

[42] However, it cannot be guaranteed that the interest rate for the LUEC calculations used by the vendors were all the same.

[43] The VK-300 designers’ data was not included as abnormally low. ** CCGT — Combined cycle gas turbine; SC/USC Coal —

Supercritical/Ultra-supercritical coal-fired plants, PV — Photovoltaic.

There are some important caveats regarding the use of the scaling law (6.3):

• The scaling law is only true if no significant design changes take place on transition to a larger or smaller capacity plant. If such changes take place (for example, the complexity of the plant design is reduced or increased), this results in a transition to another scaling law curve which may be located below or above the original one [6.5].

• According to reference [6.4], “the economy of scale may be limited due to the physical limitation to increase dimensions of some systems or components (e. g. reactor core, fuel rods and turbine blades). …The maximum size of units in an electrical grid is limited in consideration of grid stability, demand pattern, spinning reserve or other specific characteristics of the system”.

• One should keep in mind that an overall power scaling law for the entire plant is only approximate, because different components may have very different scaling exponents (for example, see Table 6.6), and thus the cost as a function of the plant unit power P is actually a polynomial of P, and it is approximated in (6.3) by a monomial.

The value of the scaling factor n is not fixed, and can be quite different for different NPPs:

[46] For example, for Korean NPPs of generally similar design OPR-1000 and APR-1400 this factor is 0.45, see Table 6.5.

• Another study, based on a French experience, gives a more detailed evaluation of the scaling factors, shown in Table 6.6. According to Table 6.6, the scaling parameter n is close to 0.6 for direct costs and is about 0.3 for the indirect costs including contingencies and owner’s costs. Also, it could be noted that the value of n increases with the increase in plant capacity,

[47] It is noted that the contributors to this report were unable to find any reference with the example of a NPP scaling law with n = 0.7 (the upper range suggested in [6.4]).

[48] Characterized by the in-vessel location of the steam generators and by the absence of large diameter piping.

75

The coefficients x, y and z correspond to the “programme” effect, and the coefficient k is related to the “productivity” effect described below. The main assumptions of the algorithm are as follows:

• The first unit built bears all of the extra FOAK cost (expressed as a factor [ 1+x]).

• The cost of engineering specific to each site is assumed to be identical for each site.

• The cost of facilities specific to each site is assumed to be identical for each site.

• The standard cost (excluding extra FOAK cost) of a unit includes the specific engineering and specific facilities for each unit.

Programme effect (construction of several units on the same site):

If T0 is the standard cost (excluding extra FOAK cost) of the sole unit on a site (see Table 6.8):

• Cost of the first unit: T= (1+x)T0

• Cost of the following units (if programme of 1 unit/site): T0.

• Cost of the 2nd unit on a site with one pair: yT0 (6.6)

• Cost of the 3rd unit on a site with two pairs: zT0

[50] Cost of the 4th unit on a site with two pairs: yT0 ,

where it is assumed that the cost of the 2nd unit of a pair is independent of the rank of the pair on the site.

Productivity effect

It is considered that a productivity effect only occurs as of the 3rd unit of a series. If n is the rank of the unit in the series, and Tn is the cost which results from taking into account the sole programme effect, it follows that:

Tn= ^ , as of n>2 (6.7)

n (1+k) n-2

[51] OKBM Afrikantov is a principal Russian design organisation for nuclear propulsion reactors: http://www. okbm. nnov. ru/.

’ However, this explanation is based on a single set of data and thus should be viewed with caution.

[53] Fuel costs also include fuel cycle costs, but here the predominant SMR strategy is to start all reactors in a currently mastered open fuel cycle with low enriched uranium as a fuel load. This strategy is also typical for all SMRs with fast reactors, except the Korean PASCAR (see Tables A1.6 and A1.7 in Appendix 1). Although a closed fuel cycle with the reprocessing of spent fuel is foreseen for most of the advanced SMRs presented in this report, SMRs are most likely to make a transfer to the new fuel cycles only when such cycles are well mastered for all other reactors. Specifically, all of the fast SMRs addressed in this report offer long refuelling intervals from 7 to 30 years, which offers a time lag for the fuel reprocessing technology to be proved and developed on a commercial scale.

[54] CHP = combined heat and power.

[55] Analysis of the Appendix 1 data has shown that most of the designers specify the production rates for non­electrical products without specifying the electric output of the plant matching exactly these production rates.

[56] As discussed in Section 6.3, this assumption is based on the analysis of only one set of consistent data and, therefore, cannot be considered as reliable. Using this assumption may, therefore, add a certain degree of conservatism to LUEC evaluation for barge-mounted plants.

: The input data and the results are presented in Table A3.5 in Appendix 3 for the discount rates of 5% and 10%.

[57] In Table 6.6 n = 0.51 corresponds to an average between the direct and the indirect costs of a NPP.

[58] Corresponds to the range of n in Table 6.7 .

*Taking into account the heat credit

NPP operation in a co-generation mode (for example, with co-production of heat or desalinated water) is not a prerogative of SMRs. On a technical level it could, in principle, be realised in NPPs with large reactors as well. Plans exist to use the reject heat of large reactors operated (or being built) in Finland and the Russian Federation for local district heating systems; however, the prospects of their realisation are not clear at the moment18,19. With regard to desalinated water production, one of [32] [33]
the considered processes — reverse osmosis — requires only electricity to pump water through a cascade of membranes, which is by default independent of the reactor capacity.

On the other hand, examples exist where NPPs with SMRs have been used or are being used for co-production of non-electrical energy products. For example, the Bilibino NPP (four 12 MWe LWGR reactors) in the Extreme North of Russia co-produces heat for district heating along with the electricity[34]. The Beznau NPP in Switzerland (two 365 MWe PWR reactors) co-produces heat for district heating for a community of about 20 000 inhabitants. A NPP in Japan produces desalinated water for the plant’s own needs [4.30].

The reasons why non-electrical applications are more often considered for SMRs are as follows:

• Some small reactors target the niche markets in remote or isolated areas where non­electrical energy products are as much a value as the electricity is.

• Many SMRs are considered as possible replacement for the currently operated combined heat and power plants (CHPs). In many countries the distribution networks serviced by CHPs are tailored to the equivalent plant capacity of 250-700 MWe [4.31]. Therefore, the use of a NPP with SMRs as a replacement would allow making full use of these networks (that cannot accommodate a large plant).

• Transport of heat or desalinated water over long distances increases costs and may incur losses. The expectation is that SMRs could be located closer to the users (see the discussion in section 9.3), which would help minimise the associated losses and costs.

The production of hydrogen or other advanced energy carriers requires high temperature heat, which makes the HTGR particularly suited for that application.

The data on energy products of SMRs is summarised in Table 4.8 for water cooled SMRs, and in Table 4.9 for non water cooled SMRs. With the exception of HTGRs, no multiple co-generation options are included, which means that, if two non-electrical products are specified, they cannot be used simultaneously.

Regarding the co-generation with SMRs:

• Among the 27 SMRs considered, seven are intended for electricity production only, and for another six the co-generation options, although not discarded, have so far not been considered at the design level.

• There is only one design — the Chinese NHR-200 — which has no electricity generation equipment within its standard configuration. It is a dedicated district heating reactor, but, as an option, it could supply heat for seawater desalination or centralised air-conditioning

[4.25] .

• Nuclear desalination is included in standard design configurations of the near-term SMART and AHWR (where part of the reject heat is used for that purpose). In all other cases it is still considered as a design option, even though some numerical evaluations have been performed and some data is included in the tables.

• Production of heat for district heating is included in standard design configurations of the Chinese NHR-200 and the following Russian designs:

— near-term marine derivative reactors, the KLT-40S (which is in the construction stage), the ABV, and the VBER-300;

— small and medium-sized BWR, the VK-300; and

— a standard four module plant configuration with the lead-bismuth cooled SVBR-100.

• Hydrogen production is traditionally targeted by HTGRs; however, the Chinese HTR-PM, for which the construction related actions have been initiated with a plan to build 19 modules in the near future, will produce only electricity.

• Atypically for sodium cooled fast reactors, the designers of the 4S have considered an option of hydrogen (and oxygen) production by high temperature electrolysis.

HTR-PM [4.1] HTGR 210* (two-module plant) No No No No

A somewhat cautious attitude of SMR designers to the inclusion of non-electrical applications in the designs of their FOAK plants reflects the fact that some recent market surveys have shown electricity applications to be in prime demand worldwide for the next decade [4.26]. With this in mind, the designers are pursuing the fastest deployment of the electricity-only versions of their SMRs, reserving the non-electrical applications for a more distant future.

An assessment performed in the previous sections indicates that the designers of advanced SMRs target to implement safety design options with the maximum use of the inherent and passive safety features (also referred to as “by design” safety features) possible for a given technology line and for a given size of the plant.

As noted in the recent IAEA publication [8.5],

An enveloping design strategy for the SMR designs… is to eliminate or de-rate as many accident initiators and/or to prevent or de-rate as many accident consequences as possible, by design, and then to deal with the remaining accidents/consequences using plausible combinations of the active and passive safety systems and consequence prevention measures. This strategy is also targeted for Generation IV energy systems and, to a certain extent it is implemented in some near-term light water reactor designs of larger capacity, such as the VVER-1000, the AP1000, and the ESBWR.

On their own, the “by design” safety features used in SMRs are in most cases not size dependent and could be applied in the reactors of larger capacity. However, SMRs offer broader possibilities to incorporate such features with a higher efficacy. As noted in [8.5], smaller reactor size contributes to a more effective implementation of the inherent and passive safety design features because of:

• “Larger surface-to-volume ratio, which facilitates easier decay heat removal, especially with a single-phase coolant.

• Reduced core power density, facilitating easy use of many passive safety features and systems.

• Lower potential hazard that generically results from lower source term owing to a lower fuel inventory, a lower non-nuclear energy stored in the reactor, and lower integral decay heat rate.”

In some cases the incorporation of passive safety features limits the reactor output, as in the HTGR case.

Otherwise, all of the presented SMR designs aim to meet the current national regulations and generally meet the international safety norms, such as formulated in the IAEA Safety Standard NS-R-1 [8.7], regarding implementation of the defence-in-depth strategy and provision of the redundant and diverse active and passive safety systems. Specifically, the IAEA report [8.5] makes a note of the approach “. applied in several water cooled, gas cooled and liquid metal cooled SMRs.” that is “.to have all safety systems passive and safety grade. In this, it is assumed that certain non safety grade active systems/components of normal reactor operation are capable of making a (auxiliary) contribution to the execution of safety functions in accidents.”

The core damage frequencies (CDFs) indicated by the designers of advanced SMRs are within the range from 10-5 to 10-8 per annum, i. e., are comparable to, or lower than the ones indicated for the state-of-the-art large capacity water cooled reactors [8.3, 8.10]. The upper boundary (10-5) mainly results from the risks associated with a non-conventional deployment (e. g., floating power plants). The indicated large early release frequencies (LERFs) are typically one order of magnitude less than the CDFs.

The available information on the safety design features of SMRs for plant protection against the impacts of natural and human induced external events is generally sparser compared to that on the internal events [8.2, 8.3, 8.4 and 8.5]. One of the reasons may be the early design stages of many of the advanced SMRs.

Where indicated, seismic design of the considered SMRs meets the recommendations of the IAEA Safety Guide [8.8]. The indicated magnitudes of safe shutdown earthquake vary significantly even among the designs belonging to the same technology lines. The values are between 0.2 g and 0.7 g PGA (3.5-4.4 on the Japanese JMA scale). These values generally match or surpass the values incorporated in the designs of currently deployed large water cooled reactors [8.3]. However, one should keep in mind that the seismic design of SMRs might be re-analysed following the Fukushima Dai-ichi accident.

All of the analysed SMRs incorporate containments and in many cases these are double containments. Some of the designs in the PWR, HTGR, sodium cooled and lead-bismuth cooled technology lines assume underground or half-embedded underground location of the reactor buildings, which are all measures that would protect the plants against an aircraft crash. However, the design basis aircraft crash is quantified for only a few designs, including the Russian marine derivative reactors. On a number of occasions aircraft crash is said to be excluded from the design consideration to be dealt with by purely administrative measures.

Few details are available on external events other than the earthquake and aircraft crash. For the plants embedded underground no explanation is provided on how such embedment would affect plant vulnerability to natural floods.

Russian floating NPPs take into account a number of the external events peculiar to their on — water location. None of the land-based designs indicate an allowance for the effects of climate change, despite the IAEA guidance on this [8.9].

The IAEA publication [8.3] suggests that “…external events should be considered at the early stages of the reactor design. If external event considerations are added at later stages, they may lead to major modifications or even unacceptable safety levels.” For the considered designs only in a few cases the designers clearly indicate that both, internal and external events have been considered when determining the CDFs and the LERFs (Russian marine derivative reactors, CAREM, IRIS, VK-300 and AHWR).

Regarding the combinations of internal and external events, the data provided for a limited number of SMRs in reference [8.3] indicates such combinations are included in the design basis of the CAREM, the VBER-300 and the IRIS.

According to reference [8.3], “.the contribution of external events to plant risk estimates is seen to be higher (in percentage) for evolutionary and innovative reactors since the internal event risks have been substantially reduced through better system design, avoidance of identified accident sequences, etc.”. The presented data for the Russian KLT-40S, where the CDF for internal events at the beginning of operation is 10-7, while the overall CDF is 10-5, may serve as an illustration of this statement, see Table A2.1(a) in Appendix 2.

A certain synergy in coping with the internal and the external events is provided by broad incorporation of the inherent and passive safety features in the advanced SMR designs. According to reference [8.3], the NPP features contributing to protection against both, internal and external events, could be:

• “Capability to limit reactor power through inherent neutronic characteristics in the event of any failure of normal shutdown systems, and/or provision of a passive shutdown system not requiring any trip signal, power source, or operator action to effect a shutdown of the reactor if the safety critical plant parameters tend to exceed the design limits.

• Availability of a sufficiently large heat sink within the containment to indefinitely (or for a long grace period) remove core heat corresponding to the above-mentioned event.

• Availability of very reliable passive heat transfer mechanisms for the transfer of core heat to this heat sink…”

Many of the advanced SMR designs presented in this report incorporate the safety design features matching the provisions of the previous paragraphs.

SMR vendors’ projections on the levelised unit cost of electricity1 (LUEC) suggest that in many cases the designers may intend to compete with large nuclear power plants (see Figure E.2). Other SMR concepts target niche applications in remote or isolated areas where the corresponding costs of generating electricity are significantly higher than in more populated areas.

Figure E.2. Comparison of the designers’ data on SMR LUEC to the projected costs of generating
electricity by NPPs with large reactors in the corresponding countries

VVER-1200 VVER-1200

ABV WER-1200 KLT-40S VBER

OECD member countries

LUEC for NPP with SMR

LUEC for NPP with large

reactors

The key parameters

In order to analyse the economics of different SMR projects and their deployment potential, the factors affecting the competitiveness are estimated and analysed in this report.

It is expected that the deployment of SMRs foreseen in the next decade would mainly take place in regulated electricity markets with loan guarantees. For such markets, the LUEC appears to be an appropriate figure of merit. The LUEC, measured in USD per MWh, corresponds to the cost assuming certainty of production costs and stable electricity prices. In view of this, LUEC [1]
was selected as the figure of merit for all estimates, evaluations and comparative assessments carried out within this study.

The assumption of a regulated market is not correct for liberalised electricity markets where prices are not regulated. In such markets the fixed costs, the total costs and the capital-at-risk matter more than LUEC. No quantitative examinations using these factors have been performed in this study.

Table 6.11 presents the data on operation and maintenance (O&M) and fuel costs for some of the SMRs addressed in this report. For comparison, included are similar data for the representative large reactors from reference [6.1].

The O&M and fuel costs are directly available only for a few SMRs, while for the majority of SMRs only the LUEC and the overnight cost were available. Where possible, we inferred the data for O&M and fuel costs using the formula (6.1) and neglecting the decommissioning costs, for a limited number of PWR- and HTGR-type SMRs. This estimate cannot give the breakdown between O&M and fuel costs.

The data presented in Table 6.11 leads to the following observations:

• There is a considerable spread of data on O&M and fuel costs even for NPPs with large reactors presented in reference [6.1]. The corresponding sums of O&M and fuel costs vary from 16.9 to 25.8 USD/MWh.

• The sums of O&M and fuel costs for SMRs vary between 7.1 and 36.2 USD/MWh. Both of the values exceeding 30 USD/MWh belong to SMRs with a long refuelling interval:

— 36.2 USD/MWh belongs to the IRIS version with a 96-month refuelling interval; and

— 33.5 USD/MWh belongs to the ABV with a 144-month refuelling interval (see Table 4.1 in Section 4.2.1).

• In both cases the increase is probably linked with a less effective fuel utilisation associated with the long refuelling intervals. For SMRs with conventional refuelling intervals, the sums of O&M and fuel costs are between 7.1 and 26.7 USD/MWh, being basically within the range for the considered NPPs with large reactors.

• The example of VBER-300 indicates that the sum of O&M and fuel costs for a barge — mounted reactor is ~50 % higher compared to the land-based one. As already mentioned, this could be explained by a larger volume of the O&M essentially required for the barge. In particular, the barge is assumed to be towed to the factory each ~12 years to undergo factory repair and maintenance.

The designers of advanced SMRs often indicate that O&M costs could be lower than those of large reactors owing to a stronger reliance of SMRs on inherent and passive safety features and to the resulting decrease in the number and complexity of safety systems [6.2, 6.8].

Regarding the fuel costs, SMRs generally offer lower degree of fuel utilisation compared to the state-of-the art large reactors, mainly because of the poor neutron economy due to small reactor core [6.2, 6.8]. Lower degrees of fuel utilisation result in higher fuel costs[53], which is most sharply manifested for SMRs with long refuelling interval, e. g., the ABV or the IRIS with a long refuelling interval (see Table 6.11).

As it was mentioned in Section 9.3, the current deterministic approach can be used to justify the reduced off-site emergency planning requirements for advanced reactors, including SMRs, in countries where the provisions for such a justification exist. However, the deterministic justification is likely to be conservative as the assumptions typically used in it are conservative.

A risk-informed approach defines the acceptance criteria based on a “probability — consequences” curve derived from the Level 3 probabilistic safety analysis (PSA), which makes it possible to take into account the smaller source terms offered by some advanced SMRs [9.14, 9.17]. Risk-informed regulations are being developed in several countries, including the United States and the Republic of Korea, and risk-informed safety standards are being developed by the IAEA [9.17]. At least one country, Argentina, already has a risk-informed approach incorporated in its national regulations for NPP licensing, see annex III in reference [9.14].

In 2007, the IAEA has published the IAEA-TECDOC-1570 Proposal of a Technology — Neutral Safety Approach for New Reactor Designs [9.17]. This publication suggests “.a methodology/process to develop a new framework for development of the safety approach based on quantitative safety goals[76], fundamental safety functions, and generalised defence-in-depth, which includes probabilistic considerations.” However, publication [9.17] is not an IAEA Safety Standard.

In the United States, the US NRC considers developing a set of performance based, risk — informed, and technology-neutral requirements for licensing of the power reactors, to be included in the NRC regulations as a new 10 CFR Part 53 that could be used as an alternative to the existing requirements 10 CFR Part 50 [9.15]. The 10 CFR Part 53 would provide a set of risk-informed requirements for both light water and non light water reactor designs [9.14]. A risk-informed regulation implementation plan (RIRIP) was adopted by the US NRC in 2006 [9.18], but the overall progress toward 10 CFR Part 53 is rather slow, and this part of the regulations is currently indicated as ‘reserved’ on the US NRC Web-site [9.19].

Once established, risk-informed national regulations could help the designers of advanced SMRs justify the reduced off-site emergency planning requirements for their designs. To achieve this, a method to quantify the reliability of passive safety systems would need to be established, as discussed in Section 9.3.

References

[9.1] United States Nuclear Regulatory Commission (US NRC), Office of Nuclear Reactors — Advanced Reactors: www. nrc. gov/reactors/advanced/pbmr. html

[9.2] United States Nuclear Regulatory Commission (US-NRC), Office of Nuclear Reactors — Advanced Reactors: www. nrc. gov/reactors/advanced/hyperion. html

[9.3] IAEA (2009), Passive Safety Systems and Natural Circulation in Water Cooled Nuclear Power Plants, IAEA-TECDOC-1624 Vienna, Austria.

[9.4] Marques M., et al (2005), “Methodology for the reliability evaluation of a passive system and its integration into a Probabilistic Safety Assessment”, Nuclear Engineering and Design 235, pp 2612-2631.

[9.5] Nayak, A. K., M. R. Gartia, A. Anthony, G. Vinod, A. Srivastav and R. K. Sinha (2007), “Reliability Analysis of a Boiling Two-phase Natural Circulation System Using the APSRA Methodology”, Proceedings of International Congress on Advances in Nuclear Power Plants (ICAPP 2007), Nice, France, May 13-18, 2007 (Paper no. 7074).

[9.6] IAEA (2010), Small Reactors without On-site Refuelling: General Vision, Neutronic Characteristics, Emergency Planning Considerations, and Deployment Scenarios, Final Report of IAEA Coordinated Research Project on Small Reactors without On-site Refuelling, IAEA — TECDOC-1652, Vienna, Austria.

[9.7] Web-page of the IAEA Coordinated Research Project “Development of Methodologies for the Assessment of Passive Safety System Performance in Advanced Reactors”: www. iaea. org/NuclearPower/Downloads/SMR/CRPI31018/CRP_Programme. pdf

[9.8] IAEA (2000), Safety of the Nuclear Power Plants: Design Requirements, Safety Standards Series, No. NS-R-1, IAEA, Vienna, Austria.

[9.9] IAEA (1999), ‘Basic Safety Principles for Nuclear Power Plants’: 75-INSAG-3 rev. 1 / INSAG-12, Vienna, Austria.

[9.10] IAEA (2005), “Innovative Small and Medium Sized Reactors: Design Features, Safety Approaches and R&D Trends”, Final report of a technical meeting held in Vienna, 7-11 June 2004, IAEA-TECDOC-1451, Vienna, Austria.

[9.11] IAEA (2006), Status of Innovative Small and Medium Sized Reactor Designs 2005: Reactors with Conventional Refuelling Schemes, IAEA-TECDOC-1485 Vienna, Austria.

[9.12] IAEA (2006), Advanced Nuclear Plant Design Options to Cope with External Events, IAEA- TECDOC-1487, Vienna, Austria.

[9.13] IAEA (2010), Small Reactors without On-site Refuelling: General Vision, Neutronic Characteristics, Emergency Planning Considerations, and Deployment Scenarios, Final Report of IAEA Coordinated Research Project on Small Reactors without On-site Refuelling, IAEA — TECDOC-1652, Vienna, Austria.

[9.14] IAEA (2009), Design Features to Achieve Defence in Depth in Small and Medium Sized Reactors, IAEA Nuclear Energy Series Report NP-T-2.2, Vienna, Austria.

[9.15] U. S. Nuclear Regulatory Commission (2005), “Backgrounder on Nuclear Power Plant Licensing Process”:

www. nrc. gov/reading-rm/doc-collections/fact-sheets/licensing-process-bg. html

[9.16] IAEA (2007), Status of Small Reactor Designs without On-site Refuelling, IAEA-TECDOC — 1536, Vienna, Austria.

[9.17] IAEA (2007), Proposal for a Technology-Neutral Safety Approach for New reactor Designs, IAEA-TECDOC-1570, Vienna, Austria.

[9.18] U. S. Nuclear Regulatory Commission (2007), “History of the NRC’s Risk-Informed Regulatory Programs”: www. nrc. gov/about-nrc/regulatory/risk-informed/history. html

[9.19] U. S. Nuclear Regulatory Commission (2010), “NRC Regulations Title 10, Code of Federal Regulations”: www. nrc. gov/reading-rm/doc-collections/cfr/

In line with its synthetic nature, the present report starts with introducing the definitions (Chapter 2), providing a brief characterisation of SMRs available for deployment (Chapter 3), and introducing in more detail the design concepts of advanced SMRs belonging to the different technology lines (Chapter 4):

• pressurised water reactors (PWRs);

• boiling water reactors (BWRs);

• advanced heavy water reactors (HWRs);

• high temperature gas cooled reactors (HTGRs) and

• sodium cooled fast reactors; and

• lead-bismuth cooled fast reactors.

Reflecting the public interest in the emerging US small and modular reactor designs, a dedicated Chapter 5 lists and analyses the design attributes of small modular reactors developed in the United States and elsewhere in the world

Chapter 6 brings into focus the various factors affecting the economic characteristics of SMRs. Numerical examples of how each of these factors, as well as their combinations, could act on the levelised unit electricity cost (LUEC) of a SMR-based plant, are provided, and the results are compared to large reactors. In addition to this, Section 6.5 touches upon the impact of co-generation and non-electrical applications on plant costs.

Section 7.1 presents the results of independent LUEC estimates performed for the selected NPP configurations with SMRs. Of the total, estimates were performed for 12 plant configurations with 8 “model” SMR designs (within the unit power range from 7.9 to 335 MWe) based on certain advanced SMR projects with significant deployment potential in the period 2010-2020.

The estimates started from published cost data for NPPs with large reactors, mostly in the construction phase or already built, and used the cost scaling law methodology together with the various correction factors described in detail in Chapter 6, to arrive at an independent LUEC value for a certain plant configuration with SMRs. The impact of the heat credit and the uncertainty ranges of the LUEC estimates were defined, and the results were then compared to the designers’ cost data (discounted to the year 2009).

In Section 7.2, the independent LUEC estimates obtained in Section 7.1 were used to evaluate the competitiveness of SMRs in the electricity and combined electricity and heat markets of several countries. The countries addressed included Brazil, China, Japan, the Republic of Korea, the Russian Federation, and the United States for electricity, and China, the Russian Federation, and the United States for combined electricity and heat generation. For the evaluations, the LUEC estimates for the various plant configurations with SMRs were compared to the projected costs of generating electricity in 2010 (reference [1.2]) using large NPPs, coal-fired plants, gas-fired plants, and renewable energy plants, including hydroelectric plants, wind plants, etc.

In Section 7.2.6, the potential of SMRs to compete in the niche markets (not suitable for NPPs with large reactors) of the Russian Federation, Canada, and the United States was evaluated using the data on electricity tariffs in the remote off-grid or local grid locations in these countries. In the evaluations, LUEC estimates for the NPP configurations with SMRs from Section 7.1 were compared to the electricity tariffs in selected locations.

Chapter 8 provides the description and summary of SMR safety designs. First, in Sections 8.1-8.7, safety designs are presented and summarised for each of the SMRs, each of the distinct SMR design groups, and each of the technology lines. Section 8.8 provides a general summary and conclusions on the SMR safety designs for internal events and external events. It also touches upon the important topics of use of passive versus active safety systems and outlines how the safety design is related to plant economics.

Chapter 9 examines licensing process for the advanced SMR projects, touching upon compliance with the current national regulations and international standards, possible delays and regulatory issues, reduced off-site emergency planning requirements, and new regulatory approaches. This section also includes a summary table of the SMR licensing status late in 2010.

Chapter 10 presents the major findings and conclusions of the present report and includes recommendations on further research in the areas that require further clarification.

The report includes three Appendices with reference data. Appendix 1 provides structured tables with design specifications for each of the SMRs addressed. In Appendix 2, structured summaries of safety design features for SMRs are given. In Appendix 3, additional data on the economics of SMRs is presented.

This report and its economic study was prepared to enable discussion and further analysis among a broad range of stakeholders, including decision-makers, public and private investors, energy economists, regulators and reactor vendors.

References

[1.1] IAEA, Power reactor information system (PRIS): www. iaea. org/programmes/a2/

[1.2] IEA/NEA (2010), Projected Costs for Generating Electricity: 2010 Edition, OECD, Paris, Tables 3.7(a-e), pp. 59-63.