Effects of Gadolinium and Europium on the Design and Submersion Criticality of a Fast Spectrum Space Reactor
- Institute for Space and Nuclear Power Studies, The University of New Mexico, Albuquerque, NM, 87131 (United States)
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.
- OSTI ID:
- 20630576
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 746; ISSN APCPCS; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CRITICALITY
DESIGN
EUROPIUM 151
FISSION
FISSION SPECTRA
GADOLINIUM 155
HEAT PIPES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
NEUTRONS
NUCLEAR FUELS
POWER SYSTEMS
REACTIVITY
REACTOR CORES
REACTOR FUELING
REACTOR VESSELS
REACTORS
RHENIUM
SPACE
SPACE VEHICLES
SPECTRAL SHIFT
URANIUM COMPOUNDS