Neutronic evaluation of GCFR core diluents and reflectors

Materials are evaluated for use as in-core diluents and as peripheral reflectors for Gas-Cooled Fast Reactor (GFR) service, using coupled Monte Carlo (MCNP) and isotopics (ORIGEN) codes. The principal performance indices compared were effects on beginning of irradiation multiplication factor, reactivity-lineated burnup, and coolant (here CO2) void reactivity. While low values of the macroscopic absorption cross section, [Sigma]a, and slowing down power, [xi] [Sigma]s, are qualitatively useful predictors of good performance, it was found that only full scope calculations were valid for quantitative assessment. For example, several materials (Ni, Nb) having poor performance as in-core diluents proved to be good reflectors. Many materials which reduced coolant void reactivity also proved detrimental to reactivity lifetime. Others, mostly the strong moderators, increased initial reactivity, but decreased reactivity lifetime. Cores fueled with plutonium exhibited a much larger void reactivity than those started up using U-235 as the fissile material. While there are no ideal candidates that are superior in all respects, considering only neutronic performance, the following appear worthy of further investgation: Metallic fuel diluents or matrices (eg. CERMET or METMET): Zr, Ti, V, Ba2Pb; High temperature fuel diluents or matrices (eg, CERMET, CERCER): SiC, BaS Cladding: Fe alloys with Cr, Al (eg ODS) Reflector: Zr3Si2, Pb, Ba2Pb, ZrS2, MoSi2 plus a variety of sulfides and silicides.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Yu, Kun, 1974-

Advisor dc:contributor.advisor

• Michael J. Driscoll.

• Nuclear Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17045

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17045