Asymptotic frequency behavior of the two-detector cross power spectral density function for a propagating perturbation of moderator density

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Nucl. Sci. Eng.; (United States)

OSTI ID:6758529

Saleh, M; Danofsky, R A; Hendrickson, R A

A number of investigators have discussed the use of two-detector cross power spectral density (CPSD) measurements to obtain the velocity of an axially propagating perturbation of the moderator density in a boiling water reactor. The basis of the measurements is the view that the detector response can be separated into local and global components where the local components, which is dominant for high frequencies (f>2 Hz), makes possible the observation of the moving perturbation associated with steam flow in the reactor. For low frequencies, the response consists of a combination of the local and global components, and correlation with the perturbation velocity is not straightforward. In the present study the asymptotic low and high frequency behavior of the CPSD is examined using the complex detector adjoint function formulation. It is shown that at low frequencies, where the wavelength of the perturbation is much larger than the axial core dimension, the phase of the CPSD and therefore the perturbation velocity correlates with the centroid spacing of detector functions involving the product of the detector adjoint function and the static flux. For high frequencies, on the other hand, the phase correlates with the detector spacing. 11 refs.

• Research Organization: Nucl Res Inst, Tuwaitha, Iraq
• OSTI ID: 6758529
• Journal Information: Nucl. Sci. Eng.; (United States), Journal Name: Nucl. Sci. Eng.; (United States) Vol. 80:1; ISSN NSENA
• Country of Publication: United States
• Language: English

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