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Sources of Radiation
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Beta decay of a radionuclide, in effect, involves either (1) a transformation within the nucleus of a neutron into a proton accompanied by the emission of an electron, or beta particle, and an antineutrino, or (2) a nuclear transformation of a proton in the decaying nucleus to a neutron accompanied by emission of a positron and a neutrino. The energy released in the process—the Q value—is shared by the electron and the antineutrino or by the positron and the neutrino. Beta decay of a nucleus may occur by any of several different nuclear transitions. For each there is a unique endpoint energy, the maximum kinetic energy of the electron or positron. Also, for each transition, there is a unique statistical distribution of energy between the electron and antineutrino or positron and neutrino, and to a very minor extent the residual nucleus. The balance of this discussion deals with the more common beta-particle emissions, with the recognition that positron emission may be treated very similarly.
Organization and Management of a Radiation Safety Office
Published in Kenneth L. Miller, of Radiation Protection Programs, 2020
Steven H. King, Rodger W. Granlund
Radionuclides chosen for nuclear medicine are usually gamma emitters without significant beta decay to ininimize patient dose. Proportional and GM counters are not very efficient for gamma-rays and a gamma detector such as a Nal(Tl) crystal may be required for surveys or measurements. The detector requires a high-voltage supply and a scaler with a discriminator. For identification of gamma-emitting radioisotopes a single- or multichannel analyzer is required. If a large number of gamma-emitting radionuclides are used, a germanium detector may be required to obtain sufficient resolution to identify the radionuclides present.
Ion Exchange
Published in Reid A. Peterson, Engineering Separations Unit Operations for Nuclear Processing, 2019
Reid A. Peterson, Garrett Brown, Amy M. Rovira
A 24% reduction in resin loading capacity was observed between cycle 1 and cycle 6 on the SL-644 resin (~4% loss of capacity per cycle). The lead column Cs capacity for sRF decreased ~2.8% per cycle. The Cs capacity decrease was attributed to combined chemical, physical, and radiolytic degradation. The cumulative dose exposed to the lead column SL-644 resin was significantly below the target 1.0 × 108 rad to have considerable impact on resin performance. At this low radiation exposure, chemical degradation may have caused most of the observed loss in resin capacity. The primary attack on the sRF resin (and other organic resins) was determined to be by oxygen. Acid elution, water rinse, and 0.1 M NaOH rinses introduce oxygen to the system and are the primary source of resin degradation. Storage of ion exchange media in an inert environment appears to stabilize the ion exchange media, but if in the presence of oxygen, the medium on top will discolor and turn black. Beta decay provides the majority of the radiation dose, and because beta particles have a very short range, they deposit all their energy in a small volume around the point at which the decay takes place.
Reactor Physics Assessment of Potential Feasibility of Using Advanced, Nonconventional Fuels in a Pressure Tube Heavy Water Reactor to Destroy Americium and Curium
Published in Nuclear Technology, 2021
For the blanket bundles containing Am (such as MA-03 and MA-04), the inventory of Am is reduced by 1100 g/bundle (~60% of initial inventory) to 1300 g/bundle (~14% of initial inventory). However, the reduction in Am is offset by the production of 238Pu from the alpha decay of 242Cm (which comes from beta decay of 242Am), 242Pu from electron capture on 242Am, and other Pu isotopes. The 241Am also undergoes alpha decay to produce 237Np. The net impact is that the total for Np + Am + Cm + Pu is reduced by 271 g/bundle for MA-03 and 142 g/bundle for MA-04. What is also notable is that the Pu composition in MA-03 and MA-04 is 62 wt% to 71 wt% 238Pu, and 18 wt% to 19 wt% 242Pu. It is anticipated that the Pu found in the spent MA bundles could be recycled in (Pu,Th)O2 bundles for subsequent destruction, although the 242Pu would be a more persistent problem, requiring neutron irradiation until it is converted into 243Pu, which will decay to 243Am, which then can be irradiated to produce fissile 244Am/244mAm (with a fission cross section of 2096 b/1561 b). The 244Am/244mAm have relatively short half-lives (10.1 h and 26 min, respectively) and will decay to 244Cm.
From First Tritium Operation of the Karlsruhe Tritium Neutrino Experiment Toward Precise Determination of the Neutrino Mass
Published in Fusion Science and Technology, 2020
Magnus Schlösser, KATRIN Collaboration
In 2016, the beamline was completed and operational in basic mode while installations of the rear section and tritium safety equipment were still ongoing. In the same year, the so-called First Light campaign took place. Photoelectrons from an ultraviolet illuminated gold rear wall were successfully transmitted through the WGTS by the magnet guidance fields to the detector. This procedure was relevant to investigate the alignment of the beamline elements with regard to the magnetic transport fields.32 In July 2017, metastable krypton, Kr, was injected into a side port of the beamline from a generator in which the conversion-electron-emitting noble gas was produced from the mother nucleus Rb (Ref. 33). Neutrino mass analysis requires a precise understanding of beta electron transport through the magnetic flux tube that connects the source section with the detector. The properties of Kr are very favorable for the characterization of the electromagnetic design of the KATRIN beamline since the K-line energy is near the tritium beta decay Q-value and the short Kr half-life minimizes the risk of contamination.32 The excellent energy resolution of the KATRIN main spectrometer of made it possible to determine the narrow K-32 and L3-32 conversion electron line widths with an unprecedented precision of (Ref. 34).
Calculation of low-energy electron antineutrino spectra emitted from nuclear reactors with consideration of fuel burn-up
Published in Journal of Nuclear Science and Technology, 2019
Eka Sapta Riyana, Shoya Suda, Kenji Ishibashi, Hideaki Matsuura, Jun-ichi Katakura, Gwang Min Sun, Yoshiaki Katano
In relation to major experiments on Neutrino Oscillation, KamLAND collaboration [2] employed the conversion method which derived the electron antineutrino flux from the experimental electron antineutrino spectra by Schreckenbach et al. [5], Hahn et al. [6], and Vogel et al. [7] for 235U, 239,241Pu and 238U, respectively. They evaluated flux for energies between 1.5 and 9.5 MeV. The energy range is suitable for well-established inverse beta-decay detection method [8] since it requires neutrino flux for energies above a threshold value of 1.8 MeV. Huber [9] and Mueller et al. [10] improved the conversion procedure and obtained revised spectra in the same energy range. The revision of conversion method leads to the finding of ‘reactor anomaly’ in the experimental spectra above 1.8 MeV [3]. Abazajian et al. [11] and Mention et al. [12] shown large interest has been aroused on sterile neutrinos. Fallot et al. [13] made use of the summation method for improvement of reactor antineutrino energy spectra predictions, with energy range above 1 MeV.