Correction for dynamic bias error in transmission measurements of void fraction

Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission wit...

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Bibliographic Details
Published in:Review of scientific instruments 2012-12, Vol.83 (12), p.125110-125110
Main Authors: Andersson, P., Sundén, E. Andersson, Svärd, S. Jacobsson, Sjöstrand, H.
Format: Article
Language:English
Subjects:
ACCURACY
Bias
COOLING
DATA ACQUISITION
Dynamical systems
Dynamics
Error analysis
Error correction
ERRORS
FLUCTUATIONS
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
NEUTRON RADIOGRAPHY
Nonlinear dynamics
SIMULATION
TIME RESOLUTION
TOMOGRAPHY
TRANSMISSION
TWO-PHASE FLOW
Void fraction
WATER COOLED REACTORS
WATER MODERATED REACTORS
X RADIATION
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Summary:Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission within the time scale of the measurement implies a bias, which can be difficult to correct for. A typical example is the tomographic or radiographic mapping of void content in dynamic two-phase flow systems. In this work, the dynamic bias error is described and a method to make a first-order correction is derived. A prerequisite for this method is variance estimates of the system dynamics, which can be obtained using high-speed, time-resolved data acquisition. However, in the absence of such acquisition, a priori knowledge might be used to substitute the time resolved data. Using synthetic data, a void fraction measurement case study has been simulated to demonstrate the performance of the suggested method. The transmission length of the radiation in the object under study and the type of fluctuation of the void fraction have been varied. Significant decreases in the dynamic bias error were achieved to the expense of marginal decreases in precision.
ISSN:0034-6748
1089-7623
1089-7623
DOI:10.1063/1.4772704