Flattop assemblies are used to measure neutron activation and reactivity coefficients. Since the neutron energies gradually decrease in the reflector, experiments may be run in various energy spectra based on the location in which they are placed.[1]
Flattop is a natural-uranium-reflected, benchmarked, fixed-geometry critical assembly machine that can accommodate plutonium or uranium cores. The fast neutron spectrum is used to provide benchmarked neutronic measurements in spherical geometry with different fissile driver materials. Key missions for Flattop include fundamental reactor physics studies, sample irradiation for radiochemical research, actinide minimum critical mass studies, detector calibration, and training. The U-233 core is no longer usable because of its high gamma-ray activity.[1]
The experiment was originally located at the Los Alamos National Laboratory Critical Experiments Facility (LACEF)[2] located at the Los Alamos Pajarito Site, otherwise known as Technical Area 18. In 2005 the Pajarito Site started to shut down and nuclear material was moved to the National Criticality Experiments Research Center (NCERC) which is located at the Nevada National Security Site. However, NCERC continues to be operated by the Los Alamos National Laboratory. The core capabilities at NCERC include Flattop along with three other critical assemblies, Comet, Planet, and Godiva-IV and a significant inventory of nuclear material items available for experimental use. NCERC critical operations commenced in 2011 and continue to be operational today.[3]
In 2012, Flattop was used for key demonstration of the use of nuclear power for space applications. The Demonstration Using Flattop Fission, or DUFF,[4] test was planned by Los Alamos National Laboratory to use Flattop as a nuclear heat source. A team from the NASA Glenn Research Center in partnership with the LANL reactor design team designed, built, and tested a heat pipe and power conversion system to couple to Flattop with the end goal of demonstrating electrical power production using technology applicable to space application.[4]
ControlsEdit
Flattop consists of a hemispherical fixed reflector and two movable quarter-spheres of reflector that can close down on the central core. One movable reflector is controlled by hydraulic pressure, while the other is actuated by a motor.[1]
ReferencesEdit
^ abcMalenfant, R. E. (June 1981). "Los Alamos Critical Assemblies Facility" (PDF). Los Alamos National Laboratory. LA-872-MS. doi:10.2172/6463833.
^Loaiza, David; Gehman, Daniel (2006). "End of an Era for the Los Alamos Critical Experiments Facility: History of critical assemblies and experiments (1946–2004)". Annals of Nuclear Energy. 33 (17–18): 1339–1359. doi:10.1016/j.anucene.2006.09.009.
^Hayes, David K.; Myers (16 July 2012). "National Criticality Experiments Research Center: Capability and Status". Institute of Nuclear Materials Management 53rd Annual Meeting (LA-UR-12-22906). Retrieved 28 November 2012.
^ abGibson, Marc A.; Briggs, Maxwell H.; Sanzi, James L.; Brace, Michael H. (December 2013). "Heat Pipe Powered Stirling Conversion for the Demonstration Using Flattop Fission (DUFF) Test" (PDF). Albuquerque: American Nuclear Society. Nuclear and Emerging Technologies for Space (NETS-2013), NASA.
September 13, 2023
flattop, critical, assembly, flattop, benchmark, critical, assembly, that, used, study, nuclear, characteristics, uranium, uranium, plutonium, spherical, geometries, surrounded, relatively, thick, natural, uranium, neutron, reflector, flattop, experiment, disa. Flattop is a benchmark critical assembly that is used to study the nuclear characteristics of uranium 233 uranium 235 and plutonium 239 in spherical geometries surrounded by a relatively thick natural uranium neutron reflector The flattop experiment disassembledFlattop assemblies are used to measure neutron activation and reactivity coefficients Since the neutron energies gradually decrease in the reflector experiments may be run in various energy spectra based on the location in which they are placed 1 Contents 1 Specifications 2 Space power research 3 Controls 4 ReferencesSpecifications EditFlattop is a natural uranium reflected benchmarked fixed geometry critical assembly machine that can accommodate plutonium or uranium cores The fast neutron spectrum is used to provide benchmarked neutronic measurements in spherical geometry with different fissile driver materials Key missions for Flattop include fundamental reactor physics studies sample irradiation for radiochemical research actinide minimum critical mass studies detector calibration and training The U 233 core is no longer usable because of its high gamma ray activity 1 The experiment was originally located at the Los Alamos National Laboratory Critical Experiments Facility LACEF 2 located at the Los Alamos Pajarito Site otherwise known as Technical Area 18 In 2005 the Pajarito Site started to shut down and nuclear material was moved to the National Criticality Experiments Research Center NCERC which is located at the Nevada National Security Site However NCERC continues to be operated by the Los Alamos National Laboratory The core capabilities at NCERC include Flattop along with three other critical assemblies Comet Planet and Godiva IV and a significant inventory of nuclear material items available for experimental use NCERC critical operations commenced in 2011 and continue to be operational today 3 Space power research EditMain article kilopower In 2012 Flattop was used for key demonstration of the use of nuclear power for space applications The Demonstration Using Flattop Fission or DUFF 4 test was planned by Los Alamos National Laboratory to use Flattop as a nuclear heat source A team from the NASA Glenn Research Center in partnership with the LANL reactor design team designed built and tested a heat pipe and power conversion system to couple to Flattop with the end goal of demonstrating electrical power production using technology applicable to space application 4 Controls EditFlattop consists of a hemispherical fixed reflector and two movable quarter spheres of reflector that can close down on the central core One movable reflector is controlled by hydraulic pressure while the other is actuated by a motor 1 References Edit a b c Malenfant R E June 1981 Los Alamos Critical Assemblies Facility PDF Los Alamos National Laboratory LA 872 MS doi 10 2172 6463833 Loaiza David Gehman Daniel 2006 End of an Era for the Los Alamos Critical Experiments Facility History of critical assemblies and experiments 1946 2004 Annals of Nuclear Energy 33 17 18 1339 1359 doi 10 1016 j anucene 2006 09 009 Hayes David K Myers 16 July 2012 National Criticality Experiments Research Center Capability and Status Institute of Nuclear Materials Management 53rd Annual Meeting LA UR 12 22906 Retrieved 28 November 2012 a b Gibson Marc A Briggs Maxwell H Sanzi James L Brace Michael H December 2013 Heat Pipe Powered Stirling Conversion for the Demonstration Using Flattop Fission DUFF Test PDF Albuquerque American Nuclear Society Nuclear and Emerging Technologies for Space NETS 2013 NASA Retrieved from https en wikipedia org w index php title Flattop critical assembly amp oldid 1084550481, wikipedia, wiki, book, books, library,
