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Differential Rod Worth Profile Affected by Axial Blankets in FFTF (Fast Flux Test Facility)

Conference · · Transactions of the American Nuclear Society
OSTI ID:6024776

The central feature of the Fast Flux Test Facility (FFTF) is the fast test reactor (FTR), which is a liquid-sodium-cooled fast reactor providing high fast-neutron flux for irradiation testing of fuels and materials. The FTR also provides a means to develop breeder reactor core components and to gain reactor systems operating experience for future liquid-metal fast breeder reactors (LMFBRs). In the FTR core, there are 82 incore positions (within rows 1 through 6) available for driver fuel assemblies and/or test assemblies. In addition, there are three safety rods and six control rods located in rows 3 and 5, respectively, in the three symmetric core sectors. The FFTF has been successfully and continuously operated for more than 11 reactor cycles. For the first 8 cycles, the core loadings were composed of the mixed-oxide driver fuel assemblies and some test assemblies. These assemblies have an active core section of 91.5 cm with 15.2-cm upper and lower reflectors. Neutronically, these assemblies are essentially symmetrical about the core center, and the differential control rod worth profiles were developed with this symmetry. Experimentally, these differential rod profiles proved to be satisfactory for these core loadings. The primary objective of this paper is to present the experimentally observed effects of axial blankets on the symmetric differential rod worth profiles.

Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
OSTI ID:
6024776
Report Number(s):
CONF-900608
Journal Information:
Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 61; ISSN TANSA; ISSN 0003-018X
Publisher:
American Nuclear Society
Country of Publication:
United States
Language:
English