Direct Alpha Spectrometry of Irradiated Nuclear Fuel
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2017-10-01 |
| Authors | David L. Chichester, James T. Johnson, Brandon Miller |
| Institutions | Idaho National Laboratory |
Abstract
Section titled “Abstract”Alpha-particle spectrometry was performed on irradiated nuclear fuel using a single-crystal (sc) diamond semiconductor particle detector. The detector was manufactured using chemical vapor deposition (CVD) methods, square in shape measuring 4.6-mm per side, and 0.5-mm thick. Square aluminum electrodes deposited on each side of the detector, 4.0-mm per side, defined the semiconductor’s sensitive area while a smaller, 1-mm diameter round aperture defined the region of the detector exposed to the fuel. This aperture was approximately 3 mm from the substrate face. The fuel sample consisted of a rectangular piece of irradiated nuclear fuel measuring approximately 2.2 mm x 0.5 mm in area and 0.15-mm thick. The fuel was made as a compact of metallic fuel powder in an aluminum matrix. The powder was an alloy of 93% uranium and 7% molybdenum (U7Mo), with a <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>235</sup> U starting enrichment of 19.75%. Fuel powder particles ranged in size from 10 μm to 100 μm in diameter. The pre-irradiation uranium density in the fuel was 8 g U cm <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>-3</sup> . The sample’s burn-up was exceptionally high at 42% FIMA (fissions per initial metal atom). The on-contact photon dose rate from the sample was measured to be ~1 R hr <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>-1</sup> (0.01 Gy hr <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>-1</sup> ), the oncontact beta dose rate from the sample was measured at ~30 R hr <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>-1</sup> (0.3 Gy hr <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>-1</sup> ). Data was collected in air for 8,572 s with the detector suspended over the fuel sample by approximately 10 mm. The spectrum collected during the measurement showed the presence of significant quantities of higher-order transmutation actinides including <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>238</sup> Pu, <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>241</sup> Pu, and <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>244</sup> Cm, in agreement with radiochemical assay data for the sample. The beta-particle event rate in the detector exceeded the alpha-particle rate by a factor of -5×10 <sup xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>5</sup> . Despite this high count rate, the extremely fast signals from the scCVD diamond semiconductor allowed operation with a dead-time of 10.62% during the measurement.
Tech Support
Section titled “Tech Support”Original Source
Section titled “Original Source”References
Section titled “References”- 2015 - Advanced Alpha-Spectrometry Simulation (AASA)