S and 4 Reactor: Operating Lifetime and Estimates of Temperature and Burnup Reactivity Coefficients

Journal Article · Fri Jan 20 04:00:00 EST 2006 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2169221· OSTI ID:20797997

King, Jeffrey C; El-Genk, Mohamed S ^[1]

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1. Institute for Space and Nuclear Power Studies, University of New Mexico, Albuquerque, NM 87131 (United States)

The S and 4 reactor has a sectored, Mo-14%Re solid core for avoidance of single point failures in reactor cooling and Closed Brayton Cycle (CBC) energy conversion. The reactor is loaded with UN fuel, cooled with a He-Xe gas mixture at {approx}1200 K and operates at steady thermal power of 550 kW. Following a launch abort accident, the axial and radial BeO reflectors easily disassemble upon impact so that the bare reactor is subcriticial when submerged in wet sand or seawater and the core voids are filled with seawater. Spectral Shift Absorber (SSA) additives have been shown to increase the UN fuel enrichment and significantly reduce the total mass of the reactor. This paper investigates the effects of SSA additions on the temperature and burnup reactivity coefficients and the operational lifetime of the S and 4 reactor. SSAs slightly decrease the temperature reactivity feedback coefficient, but significantly increase the operating lifetime by decreasing the burnup reactivity coefficient. With no SSAs, fuel enrichment is only 58.5 wt% and the estimated operating lifetime is the shortest (7.6 years) with the highest temperature and burnup reactivity feedback coefficients (-0.2709 cent /K and -1.3470 $/atom%). With europium-151 and gadolinium-155 additions, the enrichment (91.5 and 94 wt%) and operating lifetime (9.9 and 9.8 years) of the S and 4 reactor are the highest while the temperature and burnup reactivity coefficients (-0.2382 and -0.2447 cent /K; -0.9073 and 0.8502 $/atom%) are the lowest.

• OSTI ID: 20797997
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 813; ISSN 0094-243X; ISSN APCPCS
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BERYLLIUM OXIDES
BRAYTON CYCLE
BURNUP
DESIGN
ENERGY CONVERSION
EUROPIUM 151
FISSION
GADOLINIUM 155
LIFETIME
NUCLEAR FUELS
REACTIVITY
REACTIVITY COEFFICIENTS
REACTOR OPERATION
REACTORS
SEAWATER
SPACE VEHICLES
SPECTRAL SHIFT
TEMPERATURE MEASUREMENT
URANIUM NITRIDES