Contribution of fuel vibrations to ex-core neutron noise during the first and second fuel cycles of the Sequoyah-1 pressurized water reactor
Conference
·
OSTI ID:6280263
Noise measurements were performed during the first and second fuel cycles of the Sequoyah-1 pressurized water reactor (PWR) to observe long-term changes in the ex-core neutron signatures. Increases in the ex-core neutron noise amplitude were observed throughout the 0.1- to 50.0-Hz range. In-core noise measurements indicate that fuel assembly vibrations contribute significantly to the ex-core neutron noise at nearly all frequencies in this range, probably due to mechanical or acoustic coupling with other vibrating internal structures. Space-dependent kinetics calculations show that ex-core neutron noise induced by fixed-amplitude fuel assembly vibrations will increase over a fuel cycle because of soluble boron and fuel concentration changes associated with burnup. These reactivity effects can also lead to 180/sup 0/ phase shifts between cross-core detectors. We concluded that it may be difficult to separate the changes in neutron noise due to attenuation (shielding) effects of structural vibrations from changes due to reactivity effects of fuel assembly motion on the basis of neutron noise amplitude or phase information. Amplitudes of core support barrel vibrations inferred from ex-core neutron noise measurements using calculated scale factors are likely to have a high degree of uncertainty, since these scale factors usually do not account for neutron noise generated by fuel assembly vibrations. Modifications in fuel management or design may also lead to altered neutron noise signature behavior over a fuel cycle.
- Research Organization:
- Oak Ridge National Lab., TN (USA); Tennessee Univ., Knoxville (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6280263
- Report Number(s):
- CONF-841017-5; ON: DE85002317
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
ENRICHED URANIUM REACTORS
FUEL ASSEMBLIES
FUEL CYCLE
MECHANICAL VIBRATIONS
POWER REACTORS
PWR TYPE REACTORS
REACTOR NOISE
REACTORS
SEQUOYAH-1 REACTOR
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
ENRICHED URANIUM REACTORS
FUEL ASSEMBLIES
FUEL CYCLE
MECHANICAL VIBRATIONS
POWER REACTORS
PWR TYPE REACTORS
REACTOR NOISE
REACTORS
SEQUOYAH-1 REACTOR
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS