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Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
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2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
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Proving DRACO will deliver
The United States is now closer than it has been in over five decades to launching the first nuclear thermal rocket into space, thanks to DRACO—the Demonstration Rocket for Agile Cislunar Orbit.
C.-K. Chris Wang, Thomas E. Blue, Reinhard Gahbauer
Nuclear Technology | Volume 84 | Number 1 | January 1989 | Pages 93-107
Technical Paper | Radioisotopes and Isotope Separation | doi.org/10.13182/NT89-A34199
Articles are hosted by Taylor and Francis Online.
A neutronic study of an accelerator-based neutron irradiation facility (ANIF) for boron neutron capture therapy (BNCT) was performed using three-dimensional Monte Carlo transport calculations. The major components of the ANIF are a radio-frequency quad-rupole proton accelerator, a 7Li target, and a moderator assembly. Neutrons are generated by bombarding the 7Li target with 2.5-MeV protons. The neutrons emerging from the 7Li target are too energetic to be used for BNCT and must therefore be moderated. Calculations show that, among all materials for the ANIF, beryllia (BeO) and heavy water (D2O) are the best moderators. Between them, beryllia provides better neutron spectra, but D2O gives higher neutron intensities. Adding alumina (Al2O3) to D2O improves the neutron spectra, but it also increases gamma-ray contamination. The overall performance of an ANIF was evaluated for a moderator assembly composed of a 20.0-cm-high x 12.5-cm-radius beryllia cylinder reflected by 30.0 cm of alumina. Calculations show that the addition of the alumina reflector doubles the epithermal neutron intensity at the irradiation port. A 0.05 g/cm2 thick layer of 6Li was placed between the beryllia moderator and the alumina reflector to reduce the number of thermal neutrons escaping from the beryllia to the alumina, and therefore the capture gamma rays produced by aluminum in the reflector. Also, a 0.025 g/cm2 thick layer of 6Li was placed at the irradiation port of the moderator assembly to remove thermal neutrons from the field. Finally, a neutron shield of 10.0-cm-thick D2O wrapped with 6LiF was placed around the moderator assembly except at the irradiation port. The useful neutron flux (which is the flux of neutrons with energies greater than ∼1 eV) at the irradiation point, which is in front of the moderator assembly, is 4.87 x 108 n/cm2.s for a 10-mA proton beam. The corresponding total absorbed dose rates for neutron and gamma rays are 1.9 and 0.64 cGy/min, respectively. The ratio of the total neutron absorbed dose rate to the useful neutron flux is 6.5 x 10-11 cGy/n·cm-2, which is slightly higher than, but comparable to, the value of this ratio that has been estimated for moderated reactor neutron fields. The maximum usable depth (MUD) in a head phantom is calculated to be ∼7.5 cm assuming that the 10B concentration is 30 µg/g in tumor and 10 µg/g in blood, and the singlesession treatment time is 1.6 h. If the beryllia cylinder in the moderator assembly were replaced by a 15.0-cm-high x 12.5-cm-radius cylinder of heavy water, the treatment time would be reduced to 30 min, at the price of a higher entrance neutron dose to normal tissue and thus lower therapeutic gains and MUD.