ORNL-5388 - the Molten Salt Energy Technologies Web Site

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While these various proposals could be useful for increasing the energy generated
from the uranium resource base while recycling is disallowed, they will not provide the
"inexhaustible" supply of nuclear fuel that has been anticipated from the connnercial ization
of fuel recycle and breeder reactors.
and reuse of the "artificial" fissile isotopes 239Pu and 233U. It was under the assumption
that recycle would occur, initially in LWRs, that the technology for the Pu/U mixed-oxide
fuel cycle, in which 239Pu i s bred from 238U, was developed.
stated above, the proliferation resistance of the cycle as currently developed is perceived
as being inadequate.
"spiking" the fresh fuel elements with radioactive contaminants or allowing them to retain
some of the fission products from the previous cycle, either of which would discourage
seizure by unauthorized groups or states. The feasibility of these and other possible
modifications to the cycle are currently under study.
full-scope safeguards, including extensive fissile monitoring procedures, is being
investigated for use with the Pu/U cycle.
To provide such a supply would require the separation
However, for the reasons
Its pro1 iferation resistance could be increased by deliberately
In addition, the employment of
Also under study are several "alternate" fuel cycles based on the use of the
artificial fissile isotope 23% which is bred in 232Th. One such
cycle proposed by Feiveson and Taylor,2 and it is this cycle that
report. In the 23%/238U/232Th fuel cycle the 23% is mixed with
denaturant. The fertile isotope 232Th i s included to breed addit
addition of the 238U denaturant makes the proposed fuel cycle sim
cycle is the 33U/238U/2 32Th
is the subject of this
238U which serves as a
onal 233U. The
lar to the 235U/238U
cycle currently employed in LWRs i n that extracting the 233U for weapons fabrication would
require isotope separation facilities. Since 23% does not occur in nature, the cycle is
also similar to the 239Pu/238U cycle in that reprocessing will be necessary to utilize the
bred fuel. However, as suggested by the Acheson Comnittee and again by Feiveson and Taylor,
reprocessing and other sensitive activities could be restricted to secure energy centers
and still allow power to be generated outside the centers.
It is the purpose of this report to assess in the light of today's knowledge the
potential of the denatured 233U fuel cycle for meeting the requirements for electrical
power growth while at the same time reducing proliferation risks. Chapter 2 examines
the rationale for utilizing the denatured fuel cycle as a reduced proliferation measure,
and Chapter 3 attempts to assess the impact of the isotopics of the cycle, especially
with respect to an imp1 ied tradeoff between chemical inseparability and isotopic
separability of the fuel components. Chapter 4 examines the neutronic performance of
various reactor types utilizing denatured 233U fuel, and Chapter 5 discusses the require-
ments and projections for implementing the cycle. Chapter 6 then evaluates various nucl-
ear power systems utilizing denatured fuel. Finally, Chapter 7 gives sumnations of the
safeguards considerations and reactor neutronic and symbiotic aspects and discusses the
prospects for deploying denatured reactor systems. Chapter 7 also presents the overall
conclusions and recommendations resulting from this study.