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.