Gadolinium‐155 and europium‐151 are examined as alternative spectral shift absorbers to rhenium in the Scalable AMTEC Integrated Reactor space power System (SAIRS) heat‐pipe reactor. Spectral shift absorbers counteract the reactivity increase when a compact, highly‐enriched space nuclear reactor is submerged in seawater or wet sand and flooded following a launch abort accident. After all excess rhenium is removed from the reactor core, gadolinium‐155 or europium‐151 is added to the core in the form of a 0.1 mm oxide coating on the inside of the reactor vessel and/or as a nitride additive to the UN fuel. To compensate for increased parasitic neutron absorption, the UN fuel enrichment in the SAIRS reactor is increased to from 83.5% to a maximum of 94%. With 12 atom% 155GdN added to the reactor fuel, the outer diameter of the axial reflector decreased by 2 cm, and with a 155Gd2O3 coating on the inside of the reactor vessel, the reactor has $2.47 of excess reactivity at Beginning of Mission (compared to $2.08 for the rhenium base‐case) and a worst case submersion and flooding accident reactivity of −$1.12 (compared to −$0.93 for the base‐case). The resulting reactor and shield weigh 951.20 kg, for a savings of 100.94 kg over the base‐case. When 9 atom% 151EuN is used in the fuel, the outer diameter of the axial reflector is reduced by 4 cm, and the reactor has $2.53 excess reactivity and −$1.13 of reactivity in the worst‐case submersion and flooding accident scenario. The europium‐case represents a mass savings of 143.16 kg over the base‐case for a total reactor and shield mass of 908.98 kg.
Effects of Gadolinium and Europium on the Design and Submersion Criticality of a Fast Spectrum Space Reactor
SPACE TECHNOLOGY AND APPLICATIONS INT.FORUM-STAIF 2005: Conf.Thermophys in Micrograv;Conf Comm/Civil Next Gen.Space Transp; 22nd Symp Space Nucl.Powr Propuls.;Conf.Human/Robotic Techn.Nat'l Vision Space Expl.; 3rd Symp Space Colon.; 2nd Symp.New Frontiers ; 2005 ; Albuquerque, New Mexico (USA)
AIP Conference Proceedings ; 746 , 1 ; 461-472
06.02.2005
12 pages
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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