Currently, there are two definitions of such reactors widely used in the literature: small and medium-sized reactors (SMRs) and small modular reactors. Small modular reactors have attracted much attention since 2008 when several very small reactors (less than 125 MWe) were being designed in the United States. In this study, the general class of reactors with effective electric power of less than 700 MWe will be considered, but the principal focus is on reactors of less than 300 MWe.

First, the report summarises 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, see Figure E.1.

In the second part of the report, the study provides an independent estimate of electricity generation costs for the near term SMRs, and an analysis of their deployment potential. It also highlights the safety features and licensing issues of such reactors.

Figure E.1. Currently available and advanced SMRs

ABv,

VBER-300,

AHWR

SMR that could become available for

commercial deployment before 2020

The SMR concept has been considered since the early days of nuclear power. Historically, all early reactors were smaller in size compared to those deployed today. However, 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 has motivated, in some countries, the development of intentionally smaller reactors aimed at niche markets that cannot

accommodate large nuclear power plants (NPPs). Slow progress over the past two decades has resulted in about a dozen new SMR concepts reaching advanced design stages (see Table E.1), 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 are 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.

At a fundamental level, plants with SMRs are not different from those with large reactors.

However there is a need to consider SMRs separately because of the:

• Higher degree of innovation implemented in their designs; and

• Specific conditions and requirements of target markets.

Today, SMRs target two general classes of applications:

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

• Traditional deployment in direct competition with large NPPs. As we shall see, the upfront capital investment for one unit of a SMR is significantly smaller than for a large reactor. Thus there is more flexibility in incremental capacity increases, resulting in smaller financial risks, making such reactors potentially attractive to investors and for countries initiating a nuclear programme.

Some reactor components, systems or modules are entirely factory-fabricated and are subsequently transported and assembled on-site. For example, some small capacity nuclear plants foresee factory fabrication of the full nuclear steam supply system. In this case, the above-mentioned parameters y and z cannot apply and the productivity effect (factor k) becomes dominant.

Figure 6.6 presents the OKBM Afrikantov experience data on cost reduction in serial factory production of the nuclear propulsion plants [6.9]. After a certain number in the series, no additional gain in productivity is supposed.

1.1 -| 1 — 0.9 — 0.8 — I 0.7 —

CD

.>

0.6 —

CD

0.5 —

о

О

0.4 — 0.3 — 0.2 — 0.1 0

0

Using the data presented in Figure 6.6 and the equations (6.6) and (6.7):

, T

T = (1+ x) To and Tn = (n = 2),

and assuming that for the fully factory fabricated plants the only relevant factor is к (6.7) one could derive the values of x and к for the marine propulsion reactor case of Figure 6.6:

x=15%

k=5-7% (6.11)

Although к is the principal factor for full factory assembled propulsion (as well as barge — mounted power) reactors, and the evaluated value of this factor is ~3 times higher than that
recommended in [6.4] (see equation [6.11]), the overall cost reductions for each subsequent factory — fabricated nuclear propulsion plant shown in Figure 6.6 appear to be well within the ranges defined by equations (6.6) and (6.7) for conventional land-based plants built mostly on the site. This fact is independently confirmed by the OKBM Afrikantov in reference [6.9].

The off-site emergency planning measures provide a necessary protection at Level 5 of the defence-in depth “Mitigation of radiological consequences of significant releases of radioactive materials” [9.8, 9.9] and generally include the designation of a zone (or several zones) around the plant with certain restrictions on residence and activities, as well as planning of the evacuation and relocation and other measures for the emergency cases. Rated necessary from the viewpoint of protection of the population and environment from radiological consequences of beyond design basis accidents, the off-site emergency planning generally narrows the siting possibilities for NPPs and may add certain economic burdens on a new NPP project [9.6].

For SMRs, location in closer proximity to the users is rated important for the following reasons [9.10, 9.11, 9.12 and 9.13]:

• Some of the niche markets targeted by SMRs offer no space for a large off-site emergency planning zone.

• Many advanced SMRs provide for non-electrical applications, such as district heating or desalinated water production, that benefit economically from plant location in the proximity to the users.

• Some advanced SMRs (e. g., HTGRs) foresee the collocation of chemical or other process heat application plants on the site.

• SMRs do not benefit from the economy of scale and, therefore, reduction of the costs associated with the off-site emergency planning is viewed as one of the factors to combat the negative economic impacts of a smaller plant size.

The basis for justifying the reduced off-site emergency planning for SMRs is provided by a smaller source term offered by some of the SMR designs, rather than by low CDFs and LERFs which are often matched by state-of-the-art NPPs with large water cooled reactors [9.14]. Smaller source terms for advanced SMRs may result from [9.6, 9.14]:

• smaller fissile inventory;

• smaller stored non-nuclear energy (pressure, temperature, chemical energy);

• the provision of a higher margin to fuel failure and the elimination of certain initiating events by design.

Some SMR designers examine options to reduce the emergency planning zone radius for their plants, as indicated by the summary data given in Table 9.2.

Off-site emergency planning has legal and institutional aspects varying from country to country.

In all countries with an ongoing nuclear power programme there are some more or less strictly prescribed values of the emergency planning zone radius for nuclear power plants. For example, in the United States the radius is 16 km around the plant, in Japan — 10 km, in France — 5 km, in the Russian Federation — 3 km (but with a 30 km monitoring zone) [9.6], all for NPPs of essentially the same type and independent on the number of units on the site.

In some countries, e. g., the Russian Federation, there are provisions for the redefinition of the off-site emergency planning zone radius on a plant specific basis. For example, the smaller radius for a floating NPP with the two KLT-40S reactors (see in Table 9.2) has been justified using such provisions as adopted in the Russian Federation. The justification was based on a deterministic analysis with the supplementary probabilistic analysis to determine the CDF and LERF.

In other countries, e. g., the United States, the regulations could be more prescriptive. In such circumstances the progress in justifying the reduced off-site emergency planning is associated with the introduction of risk-informed safety regulations which would allow account to be taken of smaller source terms offered by some SMRs on a more realistic basis [9.6]. Reference [9.6] provides an example of the risk-informed methodology that might be used for the justification of a reduced emergency planning zone radius.

More details about the current maturity status of the risk-informed approaches are provided in the following section.

9.2 New regulatory approaches

This section provides a short summary of the emerging regulatory approaches and highlights the potential benefits to advanced SMRs that could result from the future implementation of these approaches.

The licensing of SMRs will be affected by the Fukushima accident in the same way as for large reactors. Regarding licensing status and regulatory issues relevant to SMRs, the analysis of recent publications leads to the following observations: [7]

• The SMRs available for deployment, which are the CANDU-6, the PHWR, the QP-300, the CNNP-600, and the KLT-40S, have already completed the licensing procedures in the countries of origin. The CANDU-6 and the QP-300 have also been licensed and deployed in countries other than the country of origin.

• For advanced SMR designs, three of them are in a formal licensing process in Argentina, China and the Republic of Korea, and several others are in pre-licensing negotiations in the United States and India, see Table E.1.

Regulatory issues and delays regarding SMR licensing may occur due to the following main reasons:

• Some advanced, water-cooled SMR design concepts incorporate novel technical features and components targeting reduced design, operation and maintenance complexity which will need to be justified by the designers and accepted by the regulators. There is currently no regulator which has approved such designs for construction.

• Non-water-cooled SMRs may face licensing challenges in those countries where national regulations are not technology neutral, e. g. they may be based on established water-cooled reactor practice. A lack of regulatory staff familiar with non-water-cooled reactor technologies may also pose a problem in some countries.

• Some of the advanced SMR design concepts provide for a long-life reactor core operation in a “no on-site refuelling mode”. The regulatory norms providing for justification of safety in such operation modes may be not readily available in national regulations.

Government support for licensing of selected, advanced SMRs could help overcome the corresponding delays.

Another important set of regulatory requirements concern the ability of SMRs to resist nuclear proliferation. All advanced light water PWR SMRs use conventional LEU fuel and most of the PWR SMR designs use the same fuel as large PWRs. However, particular attention should be paid to the non-proliferation potential of some heavy-water or liquid-metal cooled designs, especially if they are intended to be deployed in politically unstable areas. The IAEA has an on-going activity on the options of incorporation of intrinsic proliferation resistance features in NPPs with innovative SMRs, and the report is expected to be published soon.

Conclusions

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; [8]

• 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.

In Brazil about 80% of electricity is generated by hydropower with relatively low generating costs, see Figure 7.5 and Table 7.8. The second main source of electricity in Brazil is fossil fuel. In 2008, about 6.26% of electricity was generated from natural gas, 5.25% from wood and 3.79% from oil [7.4].

The data from Table 7.8 indicates some advanced SMRs could be competitive with the currently deployed electricity generating plants in Brazil. However, hydroelectric power plants are more competitive than any nuclear source.

Competition with other nuclear power plants should be viewed with caution. The LUEC values for nuclear in Table 7.8 are estimates with regards to the completion of the Angra 3 project. Should new NPPs with modern large reactors be considered for Brazil, SMRs would probably not be competitive.

However, some SMRs appear to be competitive with the coal — and gas-fired plants[61], as well as with some renewable plants (in the case of Brazil — biogas). The majority of the coal — and gas-fired plants operated worldwide have a capacity between 300 and 700 MWe [7.1] matching the capacity range of SMRs. In view of that, SMRs may provide a competitive replacement for decommissioned power plants in these categories not requiring an enhancement of the electricity grids, the addition of a spinning reserve, or a transition to the new site. For example, SMRs could be competitive when previously used sites do not have sufficient amounts of water for cooling towers of a large power plant. As a replacement, SMRs could effectively use the basic infrastructure remaining on the sites of
the decommissioned small and medium-sized coal — and gas-fired plants. In addition to this, plants with advanced SMRs could provide a reasonable alternative to the newly planned coal — and gas-fired plants, especially in the case of the introduction of carbon taxes.

Table 7.8, as well as the following tables in the section 7.2.2, indicates no options for competitive deployment of barge-mounted plants with very small twin-unit PWRs of 8 and 35 MWe (per unit).

The licensing of SMRs will be affected by the Fukushima accident in the same way as for large reactors. Regarding licensing status and regulatory issues relevant to SMRs, the analysis of recent publications leads to the following observations:

• All of the advanced SMRs addressed in the present study have been designed or are being designed in compliance with current national regulations.

• SMRs available for deployment, which are the CANDU-6, PHWR, QP-300, CNNP-600, and the KLT-40S, have already passed the licensing procedures in the countries of origin, which is a confirmation of their compliance with the national regulations. The CANDU-6 and the QP-300 have been deployed in countries other than the country of origin, which means they have also been licensed in those countries.

• Regarding advanced SMR designs, three of them are in a formal licensing process in Argentina (CAREM-25), China (HTR-PM) and the Republic of Korea (SMART), and several others are in pre-licensing negotiations in the United States (NuScale, mPower, Westinghouse SMR, New Hyperion Power Module) and India (AHWR).

Regulatory issues and delays regarding advanced SMR licensing may be observed due to the following main reasons:

• Some advanced water cooled SMR design concepts incorporate novel technical features and components targeting reduced design and operation and maintenance complexity which need to be justified by the designers and accepted by the regulators. Regulatory provisions for such an acceptance may be not readily available. [84]

• Some of the advanced SMR design concepts provide for a long-life reactor core operation in a “no on-site refuelling mode”. The regulatory norms providing for justification of safety in such operation modes may be not readily available in national regulations.

A governmental programme to support licensing of selected advanced SMRs could help overcome the delays due the above mentioned and other reasons.

Table 4.7 provides an evaluation of the deployment timeframes for some of the SMRs addressed in this report.

The SMRs included in Table 4.7 are those:

• for which the construction is in progress (KLT-40S);

• which are in the process of licensing (HTR-PM, CAREM-25, SMART);

• for which licensing pre-applications have been made and the dates of a formal licensing application have been defined (NuScale, mPower, Westinghouse SMR, AHWR, 4S, New Hyperion Power Module[31]);

• for which previous design versions have been licensed, or the prototypes are (or were) operated, and which are strongly supported by national programmes with deployment timeframes clearly defined at a national level (ABV, VBER-300, SVBR-100).

Table 4.7 does not include SMRs:

• that are still at a conceptual design stage (IMR, PASCAR);

• for which the basic design stage is still not completed (CAREM-300, CCR);

• for which the detailed design has been completed more than a decade ago, but no construction project was initiated (NHR-200, VK-300);

• which are targeted for deployment in the middle of 2020s, at the earliest (GTHTR300, GT-MHR);

• which were targeted for near term deployment, but then suffered a major disruption of the original plans (PBMR [previous design)), see Section 4.2.4).

The SMR designs currently being developed, and that could become available before 2020 are presented in Figure 4.2.

Table 4.7. Design status and potential timeframes for deployment of advanced SMRs

* 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.

The data given in Table 4.7 indicate that:

• By the middle of the 2010s, several PWR SMRs could be constructed (KLT-40S, ABV, CAREM-25, SMART), as well as an indirect cycle HTGR for electricity production (HTR-PM).

deployment and operation of FOAK SMRs be successful, commercial deployments of many units of these reactors may follow, starting from the first half of 2020.

• The prospects for nearer term fast spectrum SMRs (SVBR-100, 4S, New Hyperion Power Module) are less certain because of many novel features incorporated in their designs. Even if deployed by 2020, they would be prototype or demonstration plants that would need to be operated for a number of years (especially in view of the targeted long refuelling intervals) before a decision on commercialisation could be taken. It is unlikely that these SMRs could be commercialised before 2025.

• FOAK HTGRs for high temperature non-electrical applications might be deployed around 2025. Their deployment is likely to be conditioned by the progress in hydrogen (or an alternative advanced energy carrier) economy and will also be conditioned by the operation experience of the HTR-PM.

• The countries in which FOAK SMRs could be deployed within the next 10-15 years are Argentina, China, India, Kazakhstan, Republic of Korea, the Russian Federation, and the United States.

Figure 4.2. SMR designs that could be commercially deployed before mid-2020s

mPower, Westinghouse SMR. NuScale, Hyperion

AHWR

SMR that could become available for

commercial deployment before 2020

8.1 Introduction

This chapter presents a summary of safety design features for advanced SMRs belonging to different technology lines categorised in Section 4.2. SMR designs that had already been deployed and gained some positive operating experience are not addressed, as the mere fact of their deployment and successful operation is a proof of their conformity to national safety norms. An exception is the KLT-40S floating plant which was still under construction at the time of this report. However, one should keep in mind that the safety features of SMRs will be re-analysed following the Fukushima Dai-ichi accident in order to take into account the lessons learnt from it.

In recent years a number of reports addressing safety designs and issues for advanced SMRs were published by IAEA [8.1, 8.2, 8.3, 8.4, 8.5, and 8.6]. Along with the IAEA safety standards and guides [8.7, 8.8, and 8.9] those provided valuable inputs for the consideration performed in this section.

This section makes a reference to Tables A2.1-A2.6 in Appendix 2 of this report, which provide a summary of information on safety design features for each of the addressed SMRs in the following format:

• inherent and passive safety features;

• reactor shutdown systems;

• decay heat removal and depressurisation systems;

• reactor vessel and containment cooling systems;

• seismic design;

• aircraft crash design;

• core damage frequency/large early release frequency;

• emergency planning zone radius (as evaluated by the designer);

• special events considered in safety design (for barge-mounted NPPs);

• compliance with the current regulations.

Reference is also made to Tables A1.2-A1.7 in Appendix 1 of this report, which contains design specifications for each of the SMRs considered.

The structure of this section is as follows. First, safety design features are explained in brief for each technology line, see Sections 8.2-8.7. Section 8.8 provides a summary of safety designs particularly on designs for internal and external events (Sections 8.8.1, 8.8.2), passive versus active safety systems (Section 8.8.3), and safety design versus economics (Section 8.8.4). Compliance with the current regulations and licensing issues that might be faced by some of the advanced SMR designs are then examined in Chapter 9.

Currently available SMRs

At the time of this report (2011), there are eight proven SMR designs available for commercial deployment. Among these SMRs, the Canadian CANDU-6 and EC6 and the three Indian PHWR-220, 540 and 700 are pressure-tube type heavy water reactors, while the Russian KLT-40S and the Chinese QP-300 and CNP-600 are pressurised water reactors. The CANDU-6 and the QP-300 have already been deployed internationally, and there are agreements to build more of these reactors in Romania and Pakistan, respectively. Other designs among the currently available SMRs also target international markets.

All the plants except the Russian KLT-40S are traditional land-based nuclear power stations. The first-of-a-kind (FOAK) Russian barge-mounted plant with two KLT-40S reactors is still in the construction phase, targeted for deployment in 2013. This plant will provide 2^35 MWe of electricity and 25 Gcal/h of heat for district heating.

Advanced SMRs currently being developed

About twelve advanced SMRs currently being developed have reached advanced design stages and could in principle be implemented as FOAK or prototype plants before 2020. In some cases, the pre-licensing negotiations or a formal licensing process have been initiated.

As can be seen from Table E.1, the majority of these near-term advanced SMRs are pressurised water reactors (PWRs), but there is one indirect cycle high temperature gas cooled reactor (HTGR, using superheated steam in the power circuit) and one advanced heavy water reactor (AHWR). Three

12

liquid metal cooled SMRs, (two lead-bismuth cooled and one sodium cooled), are also currently being developed. However, only prototype plants are expected by 2020 due to the high degree of innovation required in relation to the long refuelling intervals.

Table E.1. Design status and potential timeframes for deployment of advanced SMRs

Westinghouse

SMR

* 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.

The electrical output of these advanced SMRs varies from 8.5 to 335 MWe (per reactor module). The majority of advanced SMRs provide for twin-unit or multi-module plant configurations with the correspondingly increased overall capacity of a nuclear power station. All Russian SMR design

concepts provide for, or do not exclude, a barge-mounted plant configuration. In other countries the SMR projects are traditional land-based. Endeavours

Some SMRs, especially those targeting applications in remote or isolated areas, propose to implement co-generation with non-electrical energy products. District heating is included in all Russian PWR SMR designs, with the production of desalinated water specified as an option. Water desalination is proposed by the Indian AHWR and Korean SMART concepts.

Reference [9.11] provides a direct comparison of the overnight costs for a twin-unit land-based and a twin-unit barge-mounted NPP with the VBER-300 reactors of 325 MWe gross electric output each. According to the data provided by the vendors (see Table 6.2), the overnight capital cost for a barge-mounted plant is 20% lower than those for a land-based plant. However a barge-mounted plant would need factory repairs and maintenance (mostly related to the barge) every 12 years and thus bears higher O&M costs. According to Table 6.2, the overall LUEC for barge-mounted VBER-300 is thus reduced by only 6% with respect to a land-based version[52].

Reference [6.12] provides a more detailed evaluation of the specific overnight capital costs for land-based and barge-mounted NPPs, presented in graphic form as Figure 6.7.