Many SMRs addressed in this section are designed (or are being designed) for both baseload as well as load-following operation. Where specified, the magnitude and rate of (daily) power variations and number of power level switches for SMRs do not differ much from those of the state-of-the-art large reactors[35]. The SMR derived from marine reactors may even have better manoeuvring capabilities than large reactors, since the original propulsion reactors are specifically designed to allow rapid power variations in a wide power range. However, the precise information on manoeuvring capabilities of advanced SMRs is currently not available.

For some co-generation plants with SMRs, e. g., the NuScale [4.8], it is proposed to change the ratio of electricity and desalinated water production at a constant thermal output of the reactor, which is expected to enable load-following operation precisely matching hourly load changes during the day.

Regarding non water-cooled SMRs, load following capability is in fact linked to the low linear heat rate of the fuel elements. For example, load-following is generally not considered for large capacity sodium cooled reactors where the linear heat rate of fuel elements can be as high as 485 W/cm. In the small sodium cooled 4S (see Section 4.2.5) the linear heat generation rate is only

39 W/cm, which is said to enable load-following operation with controlled changes to the reactor power level[36].

Regarding the compatibility with electricity grids, the general “rule of thumb” is that the unit size of a power plant should not exceed 10% of the overall grid capacity[37] [4.42]. This requirement could, perhaps, be relaxed by some appropriate smart grid designs, but this is still subject to research. By definition NPPs with SMRs can be more easily deployed using existing grid capacity, when compared to large reactors or any other large sources of power.

References

[4.1] IAEA (2006), Status of Innovative Small and Medium Sized Reactor Designs 2005: Reactors

with Conventional Refuelling Schemes, IAEA-TECDOC-1485, Vienna, Austria.

[4.2] IAEA (2007), Status of Small Reactor Designs without On-site Refuelling, IAEA-TECDOC-

1536, Vienna, Austria.

[4.3] IAEA (2010), “International Status and Prospects of Nuclear Power”. Report by the Director

General, Vienna, Austria:

www. iaea. org/About/Policy/GC/GC54/GC54InfDocuments/English/gc54inf-5_en. pdf

[4.4] IAEA, Power Reactor Information System (PRIS), home page: www. iaea. org/programmes/a2/

[4.5] IAEA (2004), Status of Advanced Light Water Reactor Designs 2004, IAEA-TECDOC-1391,

Vienna, Austria.

[4.6] Zee, S. K., et al. (2007), “Design Report for SMART Reactor System Development”,

KAERI/TR-2846/2007, KAERI, Taejon.

[4.7] Babcock & Wilcox Modular Nuclear Energy (2010), “B&W mPower Brochure”:

www. babcock. com/library/pdf/E2011002.pdf

[4.8] NuScale Power (2008), “Overview of NuScale Technology”:

www. nuscalepower. com/ot-Scalable-Nuclear-Power-Technology. php

[4.9] IAEA (1995), Design and Development Status of Small and Medium Reactor Systems 1995,

IAEA-TECDOC-881, Vienna, Austria.

[4.10] Heki, H., et al. (2006), “Design Study Status of Compact Containment BWR”, (Proc. Int. Congress on Advances in Nuclear Power Plants, Reno, NV, United States, June 4-8, 2006), ICAPP’06, No. 6372.

[4.11] 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.

[4.12] IAEA (2008), Liquid Metal Cooled Reactors: Experience in Design and Operation, IAEA — TECDOC-1569, Vienna, Austria.

[4.13] AKME Engineering company web page: www. akmeengineering. com

[4.14] Il Soon Hwang, et al. (2008), “Development of PASCAR (Proliferation-resistant, Accident — tolerant, Self-sustainable, Capsular, Assured Reactor). Design and Safety Analysis”, OECD/NEA Information Exchange Meeting on Partitioning and Transmutation 2008, Mito, Japan.

[4.15] Hyperion Power Generation (2008), “Hyperion Power Module” (White Paper), HPG,

United States: www. hyperionpowergeneration. com

[4.16] OKBM update on the KLT-40S design descriptions in IAEA-TECDOC-1391 and IAEA Nuclear Energy Series Report NP-T-2.2, OKBM Afrikantov, the Russian Federation, 2009.

[4.17] Zuoyi Zhang, Zongxin Wu, Dazhong Wang, Yuanhui Xu, Yuliang Sun, Fu Li, Yujie Dong (2009), “Current status and technical description of Chinese 2*250MWth HTR-PM demonstration plant”, Nuclear Engineering and Design 239, 1212-1219.

[4.18] OKBM update on the ABV design description in IAEA-TECDOC-1536, OKBM Afrikantov, the Russian Federation, 2009.

[4.19] KAERI update on the SMART design description in IAEA-TECDOC-1485, KAERI, Republic of Korea, 2009.

[4.20] CNEA update on the CAREM design description in IAEA-TECDOC-1485, CNEA, Argentina, 2009.

[4.21] U. S. Nuclear Regulatory Commission, Advanced Reactors: www. nrc. gov/reactors/advanced. html

[4.22] Westinghouse Electric Company update on the IRIS design description in IAEA-TECDOC — 1485, Westinghouse Electric Company, United States, 2009.

[4.23] BARC update on the AHWR design description in IAEA-TECDOC-1485, BARC, India, 2009.

[4.24] OKBM update on the VBER-300 design description in IAEA-TECDOC-1536, OKBM frikantov, Russian Federation, 2009.

[4.25] Jia Haijun, Zhang Yajun (2008), “Nuclear Seawater Desalination Plant Coupled with 200 MW Heating Reactor”, International Journal of Nuclear Desalination 2008, Jeddah, Saudi Arabia, (Session 7/No. 1)

[4.26] IAEA (2009), Common User Considerations (CUC) by Developing Countries for Future Nuclear Energy Systems: Report of Stage 1, IAEA Nuclear Energy Series NP-T-2.1, Vienna, Austria.

[4.27] CANDU-6 Technical Summary, AECL, Canada: www. aecl. ca/Assets/Publications/C6-Technical-Summary. pdf? method=1

[4.28] Enhanced CANDU-6 Technical Summary, AECL, Canada: www. aecl. ca/Assets/Publications/EC6-TS_Eng. pdf

[4.29] 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.

[4.30] IAEA (2007), Status of Nuclear Desalination in IAEA Member States, IAEA-TECDOC-1524.

[4.31] IEA/NEA (2010), Projected Costs of Generating Electricity: 2010 Edition, OECD Publications, Paris, France.

[4.32] IAEA (2008), Energy, Electricity and Nuclear Power for the period up to 2030, Reference Data Series No. 1, Vienna, Austria.

[4.33] China State Power Information Network, Power Sources — Nuclear Power:

www. sp -china. com/powerSources/np. html

[4.34] Thakur, S. (2007), Positive experience with SMRs in India, lessons learned in previous two decades and future plans, NPCIL, India.

[4.35] Antony, A. (2008), Economic Competitiveness of the Indian Advanced Heavy Water Reactor (AHWR), BARC, India.

[4.36] IAEA (2002), Heavy Water Reactors: Status and Projected Development. IAEA Technical Report Series TRS-407, Vienna, Austria.

[4.37] Il Soon Hwang, et al, “PASCAR-DEMO — a Small Modular Reactor for PEACER Demonstration”, KNS spring, 2008.

[4.38] Il Soon Hwang (NUTRECK, SNU, Republic of Korea). Private communication, 2009.

[4.39] Measuring Worth: www. measuringworth. com/uscompare.

[4.40] Measuring Worth: www. measuringworth. com/japancompare.

[4.41] Enhanced CANDU-6 Technical Summary, AECL, Canada: www. aecl. ca/Assets/Publications/EC6-TS_Eng. pdf

[4.42] IAEA (1983), Interaction of Grid Characteristics with Design and Performance of Nuclear Power Plants, A Guidebook, IAEA Technical Reports Series No. 224, Vienna, Austria.

[4.43] The European Utility Requirement (EUR) document, Volume 2 revision C, April 2001

[4.44] Power Reactor Innovative Small Module (PRISM) http://www. nrc. gov/reactors/advanced/prism. html

Recently the so-called “mini” or small and modular reactors have attracted much attention. Since 2008, several private companies have been created in the United States to support the design development, patenting, licensing and commercialisation of several new SMR concepts. Typically, the companies were created following the R&D and design development activities carried out by the US national laboratories and consulting companies. Eventually bigger private companies (including some propulsion reactor manufacturers) have followed the trend [5.1].

Table 5.1 lists the US concepts of small and modular reactors that were announced in the last few years. Table 5.1 includes the three SMR design concepts addressed in more detail in Section 4 of this report (the NuScale, the mPower, and the New Hyperion Power Module) and another design concept which is at an early design stage with prospects of further financing still unclear (the ARC-100).

Table 5.1. Small and modular reactors under development in the United States NuScale [5.2] mPower [5.1] Westinghouse SMR New Hyperion Power Module [5.3] ARC-100 [5.4] Designer, Country NuScale Power, USA Babcock & Wilcox, USA Westinghouse, USA Hyperion Power Generation, USA Advanced Reactor Concepts LLC, USA Technology line PWR PWR PWR Lead-bismuth cooled fast reactor Sodium cooled fast reactor Electric output (gross), MWe 48 125 >225 25 50-100

The attributes of small and modular reactors mentioned cumulatively in [5.1, 5.2, 5.3, and 5.4]

are:

• Small reactor size allowing transportation by truck (as well as by rail or barge) and installation in proximity to the users, such as residential housing areas, hospitals, military bases, or large governmental complexes.

• Small absolute capital outlay and an option of flexible capacity addition/removal through modular approach to plant design, deemed attractive to private investors.

• Individual containments and turbine generators for each of the reactor modules.

• High levels of safety and security boosted by the underground location of the reactor module(s), see examples at Figure 5.1 and Figure 5.2.

• Factory assembly of the complete nuclear steam supply system (NSSS) and, therefore, short construction duration on site.

• Long refuelling interval and once-at-a-time whole core reloading on the site or at a centralised factory (as a future option). [38]

• Provision for flexible co-generation options (generating electricity with co-production of heat, desalinated water, synthetic fuels, hydrogen, etc.).

Table 5.2 shows how the above mentioned cumulative attributes are distributed among the US small and modular reactor designs.

Table 5.3 shows how the same attributes are distributed among the non-US small and modular reactor designs considered in this report.

	NuScale [5.2]	mPower [5.1]	Hyperion Power Module	ARC-100 [5.4]
	Table 4.1	Table 4.1	[5.3] Table 4.6
			Lead-bismuth cooled fast	Sodium cooled fast
Technology line	PWR	PWR
reactor	reactor
Electric output (per module), MWe	125	48	25	50-100

Factory assembly and delivery of NSSS	Yes	Yes	Yes	No information
Long refuelling interval, once-at-a-time whole core reloading on the site or factory refuelling	No	Yes	Yes	Yes
Multi-module plant option	Yes	Yes	Yes	No
Flexible capacity addition/removal	Yes	Yes	Yes	No
Underground location of reactor modules	Yes	Yes	Yes	Yes

Table 5.3. Design attributes of small and modular reactors under development in countries other than the United States KLT-40S ABV 4S SVBR-100 PASCAR Russia Russia Japan Russia Republic of Korea Sodium cooled fast reactor Lead-bismuth cooled fast reactor Lead-bismuth cooled fast reactor Technology line PWR PWR Electric output (per module) MWe 35 8.5 10 101.5 37 Factory assembly and delivery of NSSS Yes Yes Yes Yes Yes Long refuelling interval, once-at-a-time whole core reloading on the site or factory refuelling No Yes Yes Yes Yes Multi-module plant option Twin-unit Twin-unit No Yes No Flexible capacity addition/ deletion No No No Yes No Partly embedded Underground location of reactor modules No No Yes underground, No information (see Figure 5.4)

The data presented in Table 5.1, Table 5.2 and Table 5.3 indicate that:

• The new small and modular (“mini”) reactor concepts being developed in the United States fit well into the technology lines described in Chapter 4.

• The new US small and modular reactors (NuScale, mPower, New Hyperion Power Module, and ARC-100) share many of their design attributes with other small reactor design concepts being developed in other countries. [39]

• Some of the SMR designs developed outside the United States offer plant configurations similar to those envisaged for the US small and modular reactors. As an example, the Japanese 4S offers an underground location for the reactor module but does not provide for a multi-module plant, see Figure 5.3; As another example, 4,-6- and 16-module plant options have been considered for the Russian SVBR-100. Some of these plant configurations provide partly-underground location for the reactor modules, see Figure 5.4.

• Even though some of the non-US SMR design concepts (as well as the US ARC-100) do not offer a flexible multi-module plant configuration, an option to cluster several plants on the same site still exists, potentially yielding certain economic benefits related to the sharing of auxiliary equipment and communications, and learning. Alternatively, single module or twin-unit plants with SMRs could be reconfigured for a flexible multi-module plant configuration at later design stages.

•

Sheltered underground location for reactor modules adds a degree of protection against aircraft crash but may pose challenges with respect to other site-specific external events, such as floods, see discussions in Section 6.8.2.

The fast spectrum sodium — and lead-bismuth cooled SMRs from Table 5.2 and Table 5.3, with the exception of the Korean PASCAR, share another common attribute — they provide for an initial fuel load based on enriched uranium rather than an uranium and plutonium mixture. The uranium enrichment is slightly below 20%.

The SVBR-100, the New Hyperion Power Module, and the ARC-100 are reported to be capable of operation with the initial uranium fuel load including a fraction of non-reprocessed spent nuclear fuel from present day light water reactors (with fission products). For the SVBR-100 this fraction is evaluated as 12%weight [5.6], while for the ARC-100 — as 25%

weight

Generically, all fast spectrum small and modular reactors are being designed to operate in a closed nuclear fuel cycle[40]. Because of a long refuelling interval (10-30 years) they do not pose a requirement for near-term availability of the reprocessing technologies, leaving a time lag for such technologies to be developed and mastered on a commercial scale. The conversion ratio is typically high, slightly below 1.0, which means that the reactor breeds almost as much fissile material as it consumes during operation. The spent fuel, after cooling and reprocessing, can be reloaded in the core with an addition of natural or depleted uranium. The reprocessing would then be limited to removal of the fission products without further separation of heavy nuclides.

Figure 5.4. Vertical cross section of a 6-module plant with SVBR-100 reactor modules [5.5] — _•? jfr

The attributes of small and modular reactors, such as small upfront capital investments, short on­site construction time (with the cost of financing accordingly reduced) and flexibility in plant configuration and applications, make such reactors attractive for private investors. However, since the nuclear industry is heavily regulated by public authorities, the public-private partnership seems to be the most probable form of cooperation to develop projects with small and modular reactors.

In the Russian Federation, the Joint Stock Company (JSC) "Evrosibenergo" and the State Atomic Energy Corporation "Rosatom" have created a public-private joint venture company “AKME Engineering” to advance the development, licensing and commercialization of the SVBR-100 project of a small lead-bismuth cooled reactor [5.8]. The near-term goal is to deploy the prototype on the site of the NIIAR research centre in Dimitrovgrad (Russian Federation) by 2017.

In the United States, formation of public-private partnership and licensing for the small and modular reactors is being supported by the Small and modular reactor programme of the Office of Advanced Reactor Concepts belonging to the Office of Nuclear Energy of the Department of Energy (DOE) [5.9]. This programme, started in May 2011, has a near-term priority to support licensing of two US designs of water cooled small and modular reactors. The target is to have these designs licensed for operation on the US territory by 2015 and to have them deployed by 2018. In the United States, development and deployment of small and modular reactors is viewed as a benefit to national industry as all (relatively small) components of such reactors could be produced indigenously [5.9].

References

[5.1] Babcock & Wilcox Modular Nuclear Energy, B&W mPower Brochure (2010):

www. babcock. com/library/pdf/E2011002.pdf

[5.2] NuScale Power, Overview of NuScale Technology (2008):

www. nuscalepower. com/ot-Scalable-Nuclear-Power-Technology. php

[5.3] Hyperion Power Generation (2008), Hyperion Power Module (White Paper), HPG,

United States: www. hyperionpowergeneration. com

[5.4] Advanced Reactor Concepts, LLC. ACR-100 Product Brochure:

www. advancedreactor. net/#/product-solutions/4537736534

[5.5] IAEA (2003), Power Reactors and Sub-Critical Blanket Systems with Lead and Lead-Bismuth as

Coolant and/or Target Material, IAEA-TECDOC-1348, Vienna, Austria.

[5.6] IAEA (2007), Status of Small Reactor Designs without On-site Refuelling,

IAEA-TECDOC-1536, Vienna, Austria

[5.7] General Atomics (2010), Energy Multiplier Module Fact Sheet,:

www. ga. com/energy/em2/pdf/FactSheet-TechnicalFactSheetEM2.pdf

[5.8] AKME Engineering company web page: www. akmeengineering. com

[5.9] Black, R. (2010), “DOE Programs for Small Modular Reactors and Advanced Reactor

Concepts”, Office of Advanced Reactor Concepts, Office of Nuclear Energy, US Department of Energy: www. nrc. gov/reading-rm/doc-collections/commission/slides/2010/20100406/black- 20100406.pdf