PWR Cores with Silicon Carbide Cladding
Name
NFC-124-PR.pdf
Description
NFC-124-PR.pdf
Size
1.54 MB
Format
Adobe PDF
Checksum (MD5)
bb6c15ee2e66d530d33a39672e4a7dd1
Author(s)
Kazimi, Mujid S.
Dobisesky, J.
Carpenter, David M.
Richards, J.
Pilat, Edward E.
Shwageraus, Evgeni
Date Issued
April 2011
Publisher
Massachusetts Institute of Technology. Center for Advanced Nuclear Energy Systems. Nuclear Fuel Cycle Program
Series/Report no.
MIT-NFC;PR-124
Abstract
The use in present generation PWRs of fuel clad with silicon carbide rather than Zircaloy
has been evaluated as an aid to reaching higher discharge burnups and to operation at higher
reactor power levels. A preliminary fuel design using fuel rods with the same dimensions as
Westinghouse RFA fuel assemblies but with fuel pellets having 10 vol% central holes has been
adopted. The central holes mitigate the higher fuel temperatures that occur due to the lower
thermal conductivity of the silicon carbide, and the open gap between the fuel and cladding that
persists over most of the irradiation. With this fuel design, it has been found possible to achieve
18 month cycles that meet present-day targets for peaking, boron concentration and shutdown
margin while allowing average discharge burnups up to 80 MWD/KgU, as well as power uprates
of 10% and possibly 20%. For non-uprated cores, the silicon carbide clad fuel has a clear
economic advantage that increases with increasing discharge burnup. Even for comparable
discharge burnups, there is a fuel cost savings of several million dollars per cycle as long as it
does not increase the cost of fabrication by more than 50%, which seems highly unlikely. With
10-20% power uprates, the economics of the fuel cycle will improve, but the total value of such
an uprate depends on the cost of needed plant modifications. Modifications to the control rod
configuration or absorbing material may also be required to meet the shutdown margin criterion,
particularly for the 20% uprate. Silicon carbide’s ability to sustain higher burnups and higher
duty than Zircaloy also allows the design of a licensable two year cycle that has a fuel cost
comparable to that of the reference 18 month Zircaloy core, and will furthermore reduce the
average annual outage time.
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