Interpretation of subcriticality measurements with strong spatial effects
This paper presents a technique to identify and isolate modal or spatial effects in frequency-domain quantities used for subcritical reactivity measurements using the /sup 252/Cf-source-driven noise analysis technique. The /sup 252/Cf technique is based on measurements of the system's response to a stochastic californium neutron source with three detectors. For certain source-detector configurations, the point kinetics theory is quite valid; however, for other configurations, spatial effects (i.e., modal contaminations) are important and special interpretations are necessary. In the past, two approaches have been successfully utilized: the computation of modal correction factors based on parallel neutronic calculations, or functional fits to a two-point kinetics model. Here, the authors present a different methodology that does not rely on extra neutronic calculations. The approach taken in this work is to functionally fit the measured CPSDs using a model that accounts for the modal contamination. The fundamental-mode component of the measured quantities is extracted from the fit, and a fundamental-mode ratio is computed. All the current theories can be applied to this ratio. Subcritical reactivities can, in this way, be estimated using the existing proven theories even in cases where the geometry or the high subcriticality would invalidate the point kinetics approximation.
- Research Organization:
- Univ. of Tennessee, Knoxville
- OSTI ID:
- 5535757
- Report Number(s):
- CONF-870601-
- Journal Information:
- Trans. Am. Nucl. Soc.; (United States), Vol. 54; Conference: Annual meeting of the American Nuclear Society, Dallas, TX, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUBCRITICALITY
REACTIVITY
CALIFORNIUM 252
MATHEMATICAL MODELS
NEUTRON FLUX
NEUTRON SOURCES
SPACE DEPENDENCE
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CALIFORNIUM ISOTOPES
EVEN-EVEN NUCLEI
HEAVY NUCLEI
ISOTOPES
NUCLEI
PARTICLE SOURCES
RADIATION FLUX
RADIATION SOURCES
RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
220100* - Nuclear Reactor Technology- Theory & Calculation