LA-UR- Approved for public release; distribution is unlimited NATIONAL LABORATORY ---- EST.1943 --- Title: Quantifyin g the Passive Ga mma Si gn al From Spent Nuclear F uel In Suppo rt of Determining the Plu tonium Conte nt In Spent Nu cl ear Fu el with Nondestruct ive Assay Au/hor(s): Michael L. Fen si n, Stephen J. To bin , Howard O. Me nlove, Martyn T. S wi nhoe In/ended for: Institute of Nuclear Mat eri als Management 's 50 th Annual M eeting Ju ly 12-16, 2 009 JW Mar ri ott Sta rr P ass Tucso n, Ariz. US A Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396. By acceptance of this article, the publisher recognizes that the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for U.S. Government purposes. Los Alamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the US. Department of Energy. Los Alamos National Laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. Form 836 (7/06)