Neutron production cross sections are reported for reactions leading to long-lived isotopes in fusion reactor materials. Pure elements and separated isotopes were irradiated with 14.6–14.8 MeV neutron fluences up to 1018 n/cm2. Undesired activities were chemically separated and the long-lived activities were measured using both liquid scintillation and x-ray spectrometry. Results are presented for the reactions56Fe(n,2n)55Fe(2.73 y),64Ni(n,2n)63Ni(100 y),63Cu(n,p)63Ni, and60Ni(n,2n)59Ni(76,000 y).
The feasibility of a practical switchable radioactive neutron source (SRNS) that can be switched on and off like an accelerator
and is field portable has been demonstrated. A stable, thin film of238Pu oxide deposited on a stainless steel planchet was the alpha source and beryllium was the light element target that produced
neutrons. This device requires minimal, if any, shielding when not in use. Design specifications and performance of this proof-in-principle
instrument are discussed.
Authors:S. F. Wolf, D. L. Bowers, and J. C. Cunnane
We have used inductively coupled plasma mass spectrometry (ICP-MS) as the primary tool for determining concentrations of a suite of nuclides in samples excised from high-burnup spent nuclear fuel rods taken from light water nuclear reactors. The complete analysis included the determination of 95Mo, 99Tc, 101Ru, 103Rh, 109Ag, 137Cs, 143Nd, 145Nd,148Nd,147Sm, 149Sm, 150Sm, 151Sm, 152Sm, 151Eu, 153Eu, 155Eu, 155Gd, 237Np, 234U, 235U, 236U, 238U, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, 241Am, 242mAm, and 243Am. The isotopic composition of fissiogenic lanthanide elements was determined using high-performance liquid chromatography (HPLC) with ICP-MS detection. These analytical results allow the determination of fuel burn-up based on 148Nd, Pu, and U content, as well as provide input for storage and disposal criticality calculations. Results show that ICP-MS along with HPLC-ICP-MS are suitable of performing routine determinations of most of these nuclides, with an uncertainty of ±10% at the 95% confidence level.
Authors:K. Bower, A. Angel, R. Gibson, T. Robinson, D. Knobeloch, and B. Smith
Advances in liquid scintillation counting (LSC) technologies, such as imporved scintillation cocktail formulations and alpha-beta radiation discrimination, make LSC suitable for applications in uranium process chemistry. Ease of use, low cost, and the huge dynamic range of LSC are distinct advantages for analytical support of actinide processing. All uranium isotopes decay primarily with alpha radiation emission. The immediate short-lived daughters of238U are234Th and234Pa. These nuclides are beta emitters having energy bands that overlap the uranium bands in a liquid scintillation spectrum. The resolution of these overlapping bands by alpha-beta radiation discrimination is useful for uranium quantification and purity verification. Protactinium-234 is a high-energy beta emitter that can be further identified and quantified from it's Cherenkov radiation. Energy spectra were collected on the Packard 2500AB liquid scintillator analyzer for uranyl solutions in diisopropylnaphthalene and pseudocumene based scintillator cocktails. Calibration curves were prepared for nitric, hydrochloric, and sulfuric acid media. Base titrations demonstrated the effect of acid quenching on those system. Ion exchange and water soluble polymer extraction studies are readily followed using liquid scintillation methods.
Authors:V. Sullivan, D. Bowers, M. Clark, D. Graczyk, Y. Tsai, W. Streets, M. Vander Pol, and M. Billone
A work plan was desired that would produce data for a wide array of actinide and fission-product isotopes with reasonably
good accuracy and relatively low cost. An analysis scheme involving a fairly small number of separations, dilutions, and measurement
methods was used to generate information on 74 isotopes in two spent-fuel samples of >70 GWd/MTU burnup. Some of the measured
isotopes are of high interest for burnup-credit evaluations and had not been reported previously for high-burnup fuels.