T.M. Coles, S.S. Chirayath, and W.S. Charlton,
"Nuclear Forensics Signature Analysis of Thermal Reactor Produced Weapons-grade Plutonium,"
INMM 54th Annual Meeting, 14-18 July 2013, Palm Desert, California, USA.
One of the objectives of this project is to utilize
computational models to reliably predict the unique intrinsic
signature in the weapons-grade plutonium separated from a CANDU
(CANada Deuterium Uranium) thermal reactor. This signature will be
compared with the experimental measurements consisting of Plutonium
URanium EXtraction (PUREX) reprocessing of natural UO2 samples
irradiated in the Oak Ridge National Lab-High Flux Isotope Reactor
(ORNL-HFIR). The CANDU reactor can produce weapons-grade plutonium
if the fuel is discharged intentionally at low burn-up. CANDU core
modeling is made using MCNPX-2.7 radiation transport code.
MCNPX-2.7 burn-up calculations can determine the resulting isotopic
makeup of actinides, fission products and trace elements in the
discharged fuel. The specific isotopes for the analysis were chosen
based upon their half-lives, activity, and the fuel reprocessing
decontamination factor. The discharged fuel of interest was a
single bundle of natural UO2 , which saw a burn-up of 1000 MWD/MTU.
During the CANDU reactor core burn-up simulation, certain fuel
channel bundles were replaced with fresh ones to simulate the
process of on-line refueling of the reactor; however it was later
determined that utilizing a single bundle computational model with
reflective boundary conditions on all sides was sufficient. The
single bundle was burnt to the desired burn-up and the final fuel
composition of that bundle was used in the isotopic analysis. The
signature of plutonium produced in the CANDU reactor will be
compared to that produced from a fast breeder reactor (FBR) and a
separate abstract is submitted for the FBR side of the project. The
differences in the neutron energy spectrum of the reactor can cause
variations in the isotopes of plutonium, fission products and other
minor actinides produced between the two reactor types.
Correlations between the findings from the two different reactor
types will be investigated, along with being compared to the
experimental data. The goal is, if smuggled weapons-grade plutonium
is caught, analysis of intrinsic isotope signature associated with
it should be able to ascertain the type of reactor that produced
it. The experimental data is not yet available and will become
available in the latter half of this project.
Associated Project(s):Plutonium Fingerprinting for Forensics (PuFF) Project