D.J. Sweeney and W.S. Charlton ,
"Physical Mechanisms for Fission Product Concentration Differences from Variations in Reactor Power History,"
Proceedings of 49th Annual INMM Meeting
, Nashville, TN, July 13-17, 2008.
A method for uniquely determining power history characteristics
of spent fuel assemblies based on the concentration of various
fission products in the fuel assembly has been developed. It is
envisioned that this method could be used as a transparency aid at
reprocessing facilities to verify the identity of spent fuel
assemblies. Specific fission product concentrations measurably vary
as a result of differences in reactor power history. A discussion
of the physical properties of various fission products responsible
for concentration differences along with the mechanisms by which
these properties produce concentration differences is presented.
Several different mechanisms based on variations in the physical
properties are illustrated through simplified models. These models
led to the identification of an extensive list of possible monitor
ratios which is presented. A case study was also performed to
assess the distinguishing capabilities of the given monitors. The
variations between cases include modifications to specific power,
the number of shutdowns, and the duration of the shutdowns while
maintaining a constant final burnup. For all but one of the cases a
monitor ratio is shown to vary by at least 20% with the base case
while some ratio differences for cases with simple modifications
reached 300%. This paper concludes with a proposed technique using
the presented monitor ratios to verify the identity of spent fuel
assemblies based on differences in reactor power history.
Associated Project(s):Transparency Methods Development using Fission Product Signatures