Comparative neutronic analysis of Pb-versus Na-cooled LMR cores

Conference · Sat Feb 01 00:00:00 EST 1992

OSTI ID:10119108

Liaw, J R; Fujita, E K; Wade, D C

A comparative neutronic study has been conducted on several LMR cores using both lead-magnesium eutectic alloy (97.7% Pb -- 2.3% Mg) and sodium as coolant. In order to have a consistent comparison for these two coolants on a common basis, i.e. interchangeable designs, this study used exactly the same reactor core layout, assembly design parameters, and compositions for structure material. Only driver fuel enrichments were adjusted respectively for these two coolants in order to meet the same set of requirements for specified burnup cycles. Equilibrium cycle performance and coolant void worth were calculated for five different lattice designs, first for sodium coolant and then for Pb-Mg coolant. Our results indicated a better neutron economy is achieved in cores using Pb-Mg as coolant which generally have higher breeding performance, small burnup reactivity swing, and lower fissile enrichment. On the otherhand, linear heat rate goes up, power peaking worsens, and peak fast fluence increases in Pb-Mg cooled cores. Some of these problems may be mitigated if the design constraint of interchangeability were relaxed. Special emphasis has been put on the void worth comparison between Na and Pb-Mg coolant. quite large negative void worths were obtained for several cases using Pb-Mg as coolant where the Na coolant would have otherwise yielded positive values. The difference is void worths were explained from basic physical principles involved in voiding these two coolants. The large negative void worth with Pb-Mg coolant is mainly caused by the enhanced leakage component rather than the direct spectral hardening effects of heavy coolants.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 10119108
• Report Number(s): ANL/CP-73386; CONF-920308-9; ON: DE92007381
• Resource Relation: Conference: American Nuclear Society (ANS) topical meeting on advances in reactor physics,Charleston, SC (United States),8-11 Mar 1992; Other Information: PBD: [1992]
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
22 GENERAL STUDIES OF NUCLEAR REACTORS
LMFBR TYPE REACTORS
REACTOR PHYSICS
COOLANTS
COMPARATIVE EVALUATIONS
REACTOR CORES
BURNUP
SODIUM
LEAD ALLOYS
MAGNESIUM ALLOYS
VOIDS
NEUTRON SPECTRA
NEUTRON FLUX
CROSS SECTIONS
REACTIVITY
210500
220100
POWER REACTORS
BREEDING
THEORY AND CALCULATION