Page 195 - Managing Global Warming

Current and future nuclear power reactors and plants 157

Using liquid sodium as the reactor coolant, a high power density with low coolant
volume fraction and operation at low pressure can be achieved. While the oxygen-free
environment prevents corrosion, sodium reacts chemically with air and water, and
requires a sealed coolant system.
Plant size options under consideration range from small, 50 to 300MW el , modular
reactors to larger plants up to 1500MW el . The outlet temperature is 500–550°C for
the options, which allow the use of the materials developed and proven in prior
fast-reactor programs.
The SFR closed fuel cycle enables regeneration of fissile fuel and facilitates man-
agement of minor actinides. However, this requires that recycle fuels be developed
and qualified for use. Important safety features of the Generation IV system include
a long thermal response time, a reasonable margin to coolant boiling, a primary system
that operates near atmospheric pressure, and an intermediate sodium system between
the radioactive sodium in the primary system and the power conversion system.
Water/steam (Rankine cycle), supercritical carbon dioxide, or nitrogen (Brayton
cycle) can be considered as working fluids for the power conversion system to achieve
high performance in terms of thermal efficiency, safety, and reliability. With innova-
tions to reduce capital cost, the SFR is aimed to be economically competitive in future
electricity markets. In addition, the fast neutron spectrum greatly extends the uranium
resources compared to thermal reactors. The SFR is considered to be the nearest-term
deployable system for actinide management.
Much of the basic technology for the SFR has been established in former fast-
reactor programs, and was confirmed by the Ph enix (French for Phoenix) end-of-life
tests in France, by operation of the Monju reactor in Japan, and the lifetime extension
of BN-600 in Russia. New programs involving SFR technology include the Chinese
experimental fast reactor (CEFR), which was connected to the grid in July 2011,
India’s prototype fast breeder reactor (PFBR), and the latest success in Russia with
putting into operation the BN-800 reactor.
The SFR is an attractive energy source for nations that desire to make the best use
of limited nuclear fuel resources and manage nuclear waste by closing the fuel cycle.
Fast reactors hold a unique role in the actinide management mission, because they
operate with high energy neutrons that are more effective at fissioning actinides.
The main characteristics of the SFR for actinide management mission are:

l Consumption of transuranics in a closed fuel cycle, thus reducing the radiotoxicity and heat
load, which facilitates waste disposal and geologic isolation, and
l Enhanced utilization of uranium resources through efficient management of fissile materials
and multirecycle.
High level of safety achieved through inherent and passive means also allows accom-
modation of transients and bounding events with significant safety margins.
The reactor unit can be arranged in a pool layout or a compact loop layout. Three
options are considered:
(1) A large-size (600–1500MW el ) loop-type reactor with mixed uranium-plutonium oxide fuel
and potentially minor actinides, supported by a fuel cycle based upon advanced aqueous
processing at a central location serving a number of reactors.