PWR Transition to a Higher Power Core Using Annular Fuel
Name
NFC-095.pdf
Description
NFC-095.pdf
Size
11.81 MB
Format
Adobe PDF
Checksum (MD5)
a91e7360952cc48ec1dfa018eb90f508
Author(s)
Beccherle, J.
Hejzlar, Pavel
Kazimi, Mujid S.
Date Issued
September 2007
Publisher
Massachusetts Institute of Technology. Center for Advanced Nuclear Energy Systems. Nuclear Fuel Cycle Program
Series/Report no.
MIT-NFC;TR-095
Abstract
The internally and externally cooled annular fuel is a new type of fuel for PWRs that
enables an increase in core power density by 50% within the same or better safety
margins as traditional solid fuel. Each annular fuel assembly of the same side dimensions
as the 17x17 solid fuel assembly has 160 annular fuel rods arranged in a 13x13 array.
Even at the much higher power density, the fuel exhibits substantially lower temperatures
and a Minimum Departure From Nucleate Boiling (MDNBR) margin comparable to that
of traditional solid fuel at nominal (100%) power. The major motivation for such an
uprate is reduction of electricity generation cost. Indeed, the capital cost per kWh(e) of a
new reactor would be smaller than the standard construction of a new reactor with solid
fuel.
Elaborating on previous work, we study the economic payoff of an uprate of existing
PWRs given the expected cost of equipment and also cost of money using different
assumptions. The fate of the already bought solid fuel is investigated. It is demonstrated
that the highest return on investment is obtained by gradually loading annular fuel in the
reactor core such that immediately before shutting the reactor down for the uprate
construction, two batches in the core are of the annular fuel.
This option implies running a core with a mixture of both annular and solid fuel
assemblies. In order to prove the technical feasibility of such an option, the thermalhydraulics
of this mixed core is investigated and the MDNBR is found to be either
unaffected or improved. Consequently, a neutronic model is developed to verify and
validate the neutronic feasibility of the transition from solid to annular fuel. This
involvements assessment of the peaking factors and capability to provide control poisons
within allowable concentrations
The overall conclusion of this work is that annular fuel is a very promising option for
existing reactors to increase their power by 50%, as it enables a significant uprate with an
attractive return on investment. We show that, by a smart management of the transition,
an internal return on investment of about 22–27% can be achieved.
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