Over the years, the IAEA has published a number of comprehensive reports on design status of the advanced reactors belonging to different technology lines, including SMRs. These reports contain some useful definitions which are also adopted in the present report.

According to the IAEA [2.1, 2.2]:

• Small reactors are reactors with the equivalent[11] electric power less than 300 MW.

• Medium-sized reactors are reactors with the equivalent electric power between 300 and 700 MW.

The IAEA-TECDOC-936 “Terms for describing new, advanced nuclear power plants” [2.3] defines an:

• Advanced design as a “design of current interest for which improvement over its predecessors and/or existing designs is expected”.

A continued advanced reactor development project passes sequentially through the design stages of conceptual design, basic (or preliminary) design and, finally, detailed design. The attributes of these design stages are detailed in the IAEA-TECDOC-881 [2.4]. In short:

• the conceptual design stage results in the development of “initial concept and plant layout”;

• the basic (or preliminary) design stage ends up with the “essential R&D completed (except non-critical items)”; and

• the detailed design stage yields the “complete design of the plant, except very minor items. It can be unified (for example, for an envelope of site conditions) or site-specific”.

According to the definition given in IAEA-TECDOC-1536 [2.5]:

• Small reactors without on-site refuelling are reactors designed for infrequent replacement of well-contained fuel cassette(s) in a manner that prohibits clandestine diversion of nuclear fuel material.”

The above definition addresses both factory fabricated and fuelled reactors and the reactors for which infrequent reloading of the whole core is performed on the site. For the purposes of the present report, the IAEA definition [2.5] was not followed and the reactors with the above mentioned features were categorised separately.

• Distributed deployment refers to a situation when a NPP with a single reactor module or a twin-unit NPP is deployed on each of the many sites.

• Concentrated deployment assumes clustering of multiple NPPs, or construction of a multi­module plant, on a site.

All safety related terms used in Sections 6 and 7 of this report follow the definitions suggested in the IAEA Safety Glossary [2.6].

References

[2.1] IAEA (1997), “Introduction to Small and Medium Reactors in Developing Countries”,

Proceedings of two Advisory Group meetings held in Rabat, Morocco and Tunis, Tunisia, IAEA-TECDOC-999, Vienna, Austria.

[2.2] 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.

[2.3] IAEA (1997), Terms for Describing New, Advanced Nuclear Power Plants, IAEA-TECDOC-

936, Vienna, Austria.

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

IAEA-TECDOC-881, Vienna, Austria.

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

1536, Vienna, Austria.

[2.6] IAEA (2007), IAEA Safety Glossary: 2007 Edition, Vienna, Austria.

At the time of this report (2011) there were eight proven SMR designs with a prospect of international deployment, see Figure 3.1. Some of those designs have already been completed or are already in operation; basic characteristics of these designs are summarised[12] in Table 3.1.

Of these designs, the CANDU-6, the EC6 and the PHWR-220 are pressure-tube type heavy water reactors. The QP-300, CNP-600 and KLT-40S are pressurised water reactors. Most of the plants provide for both distributed and concentrated (several plants on a site) deployment. For a floating plant with two KLT-40S reactors, location of more than one barge on a site has not been considered yet. The EC6 provides for a twin-unit option, the KLT-40S is a twin-unit.

The construction period ranges from four to seven years, with the shortest one for the Russian KLT-40S and the longest one for the Chinese QP-300 and CNP-600.

All of the SMRs in Table 3.1 have containments, and the PHWR-220 and the KLT-40S offer a double containment.

Figure 3.1. SMRs available for commercial deployment in 2010

CANDU-6

EC6

QP300, CNP-600

PHWR-220,r PHWR-540 PHWR-700, <

OECD member countries

Candidates for accession

Enhanced Engagement countries

3.1 Land-based heavy water reactors (HWRs)

Except for EC6, all heavy water reactors from Table 3.1 have already been deployed in the country of origin and in some cases abroad. The CANDU-6 and the QP-300 have been deployed

internationally, and there are agreements to build more of these reactors in Romania and Pakistan, respectively. All deployments of the CANDU-6 since 1996, as well as all deployments of the PHWR-220 since 2000 are reported to have been accomplished on schedule (or even ahead of it) and without exceeding the budget [3.1, 3.2].

The CANDU-6 reactors are the newest in the CANDU series that have been deployed. The EC-6 is an evolutionary modification of the CANDU-6, based on the experience of the latest deployed CANDU-6 reactors.

The PHWR-220 is an Indian development from the previous low-power CANDU reactors. The safety features of the initial design have been improved resulting in increased level of safety of 15 reactors of this type currently operating in India [3.3].

The operational lifetime of currently available heavy water SMRs is typically 40 years, with the exception of the EC6 for which it is 60 years. The availability factors are quite competitive ranging between 79% and 90% for all SMRs in Table 3.1.

The CANDU-6, the EC6 and the PHWR are refuelled online. This is typical of all pressure tube type heavy water reactors.

A nuclear desalination option is being considered (but still not realised) for the Indian PHWR-220. More details about energy products of the SMR available for deployment can be found in Section 4.4.

3.2 Land-based pressurised water reactors (PWRs)

The QP300 is a low power conventional loop-type PWR with a maximal fuel burn-up of 30 MWday/kg and a one-year refuelling interval. In the CNP-600, fuel burn-up is increased to above 45 MWday/kg, and the refuelling interval is 1.5 years.

The QP300 and the CNP-600 use conventional refuelling in batches with a refuelling interval of 14 and 18 months, respectively.

The operational lifetime of QP300 is 40 years, and for the CNP-600 it is 60 years.

The QP300 incorporates a passive safety system of core flooding with borated water. The CNP-600 incorporates two passive safety systems, one for passive heat removal from the secondary side of the steam generator, and another for passive containment cooling.

3.3 Barge-mounted PWRs

The first-of-a-kind (FOAK) KLT-40S (see Figure 3.2) is the only barge-mounted SMRs in Table 3.1. It is currently under construction and expected to start operation in 2013. This plant offers a maximum of 80 MWe with the co-generation option disabled.

The projected plant operational lifetime is 40 years, and the targeted energy availability factor is

85%.

In the KLT-40S, the whole core is refuelled after the end of its fuel cycle. However, the fuel bundles are shuffled in the core with an interval of slightly above two years. Such refuelling scheme, in which fuel loading and unloading are performed on the barge, is adopted for the cermet fuel of slightly less than 20% enrichment in 235U used in KLT-40S.

SMR design and vendor	Reactor type and deployment (land or barge)	Thermal/ Electric output, MW (gross)	Availability/ Plant lifetime	Construction period	Mode of refuelling/ Refuelling interval	Mode of deployment/ Plant configuration*	Deployment status
CANDU-6	PHWR		88.8%/40 years			Distributed or concentrated	11 units deployed and operated in
AECL,	2 064/715	60 months	On line	China, Canada,
Canada [3.6]					Republic of Korea and Romania
EC6 AECL, Canada [3.1]	PHWR	2 250/ 730-745	90%/60 years	57 months	On line	Distributed or concentrated/ Twin-unit option	Ready for deployment (evolution of a proven CANDU-6)
PHWR-220**	PHWR		89.3%/40 years			Distributed or concentrated	15 units in operation in India
NPCIL, India	862/220	60 months	On line
[3.7]
QP300 CNNC, China [3.7]	PWR	1 000/ 310-325	79%/40 years	84 months	In batches/14 months	Distributed or concentrated	One unit deployed in China and 1 in Pakistan, one unit under construction in Pakistan
CNP-600 CNNC, China [3.8]	PWR	1 936/644	87%/60 years	83 months	In batches/18 months	Distributed or concentrated	2 units in operation and 2 units under construction in China
KLT-40S JSC “Rosatom”, Russia [3.4,3.8]	PWR	2×150/2×35 2×40 MWe with non­electrical applications disabled	85%/40 years	48 months	Whole core/Shuffling of fuel assemblies in 27.6 months	Distributed/Twin- unit	Under construction in Russia, deployment scheduled for 2013

* Here and after, the default is a single unit plant.

** During the 54th session of the IAEA General Conference in September 2010, India announced its intentions to also export NPPs with the indigenous PHWR-540 and PHWR-700 reactors (similar to PHWR-220 but having higher outputs of 540 and 700 MWe [gross]).

Of the SMR designs available for deployment, only the barge-mounted plant with the two KLT-40S reactors provides for operation in co-generation mode with co-production of heat for district heating.

The KLT-40S is based on the experience of about 6 500 reactor-years in operation of the Russian marine propulsion reactors [3.4]. The KLT-40S design is different from conventional PWRs. This difference is discussed in more detail below.

The KLT-40S offers a compact primary containment of less than 12 m in size. The plant surface area indicated for the KLT-40S is 8 000 m2 on the coast and 15 000 m2 in the bay.

References

[3.1] Enhanced CANDU-6 Technical Summary, AECL, Canada:

www. aecl. ca/Assets/Publications/EC6-TS_Eng. pdf

[3.2] India completes two CANDU reactors under budget, ahead of schedule:

www. democraticunderground. com/discuss/duboard. php? az=view_all&address=115×66278

[3.3] Deolalikar, R. (2008) “Safety in Nuclear Power Plants in India”, Indian Journal of Occupational

and Environmental Medicine, 200, Volume 12, Issue 3: www. ncbi. nlm. nih. gov/pmc/articles/PMC2796747/

[3.4] 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.

[3.5] Nuclear Engineering International, January 2010:

www. neimagazine. com/journals/Power/NEI/January_2010/attachments/KLT-

40S%20Data%20&%20Diagram. pdf

[3.6] AECL, CANDU-6 Technical Summary, Canada:

www. aecl. ca/Assets/Publications/C6-Technical-Summary. pdf? method=1

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

IAEA-TECDOC-881, Vienna, Austria.

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

Vienna, Austria.