PLENTIFUL ENERGY

levels, actually higher than the direct costs. Interest on the borrowed capital kept
adding on as plant construction was held up by one legal challenge after another. A
key to capital cost competitiveness for the fast reactor, as for any other, is keeping
the indirect costs down to a reasonable level; in particular, construction hold-ups
cannot be tolerated. In maturity, there is no reason why the indirect costs for fast
reactors would be any higher than those of LWRs.
The most effective measure to reduce the indirect costs is to standardize the plant
design so that site-specific engineering and design costs are avoided. The seismic
isolation system can help to keep the standard design applicable for a variety of
potential sites regardless of the site-specific seismic design spectra. The seismic
isolation system itself can be fine-tuned to cope with any site-specific seismic
design criteria, leaving the plant structural design as a standardized plant. [8-9]
As for the direct cost components, the reactor equipment cost may be higher for
the fast reactor because of higher-temperature structural materials and additional
equipment associated with the intermediate heat transport system. On the other
hand, the containment building and structures can be reduced in size and in the
commodity amounts, because high pressure containment is not required for fast
reactors. The balance of the equipment systems, such as the turbine, could be
slightly less for fast reactor because of a higher thermal efficiency and hence
reduced thermal output for any given electrical output. On balance, the capital cost
for fast reactors should be in the same range of variations that exist for LWRs.
In a recently completed commercial feasibility study done by the Japan Atomic
Energy Agency, the capital cost for their 1,500 MWe JAEA Sodium Cooled Fast
Reactor (JSFR) was estimated to be less than that of an equivalent size PWR. [10-
11] A significant reduction in the construction commodities and building sizes was
achieved by a number of design changes, such as combining the IHX and pump into
one unit, shortening the piping length with advanced alloys, and reducing the
number of loops with large components.
Overall, though, because of first-of-a-kind costs, capital cost competitiveness is
unlikely in the first few fast reactor plants. Too much focus should not be placed on
the capital cost reduction for the early reactors. Risk in terms of large sodium
component reliability and system engineering is more important than the economies
of scale that push toward larger reactor sizes. Initial fast reactors should be in the
range of 600 MWe sizes before scaleups begin. Economies of scale will naturally
push to a larger size in a mature economy. Even for the mature LWR industry, the
reactor size has been in the 1,0001,300 MWe range and the scaleup to
1,5001,800 MWe size is only now being planned for the next evolutionary plants,
after thousands of reactor-years experience with the current generation.
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