Matrix and position correction of shuffler assays by application of the alternating conditional expectation algorithm to shuffler data
The {sup 252}Cf shuffler assays fissile uranium and plutonium using active neutron interrogation and then counting the induced delayed neutrons. Using the shuffler, we conducted over 1700 assays of 55-gal. drums with 28 different matrices and several different fissionable materials. We measured the drums to dispose the matrix and position effects on {sup 252}Cf shuffler assays. We used several neutron flux monitors during irradiation and kept statistics on the count rates of individual detector banks. The intent of these measurements was to gauge the effect of the matrix independently from the uranium assay. Although shufflers have previously been equipped neutron monitors, the functional relationship between the flux monitor sepals and the matrix-induced perturbation has been unknown. There are several flux monitors so the problem is multivariate, and the response is complicated. Conventional regression techniques cannot address complicated multivariate problems unless the underlying functional form and approximate parameter values are known in advance. Neither was available in this case. To address this problem, we used a new technique called alternating conditional expectations (ACE), which requires neither the functional relationship nor the initial parameters. The ACE algorithm develops the functional form and performs a numerical regression from only the empirical data. We applied the ACE algorithm to the shuffler-assay and flux-monitor data and developed an analytic function for the matrix correction. This function was optimized using conventional multivariate techniques. We were able to reduce the matrix-induced-bias error for homogeneous samples to 12.7%. The bias error for inhomogeneous samples was reduced to 13.5%. These results used only a few adjustable parameters compared to the number of available data points; the data were not over fit,'' but rather the results are general and robust.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 7066557
- Report Number(s):
- LA-UR-92-2361; CONF-9207102-36; ON: DE92018905
- Resource Relation:
- Conference: Institute of Nuclear Materials Management (INMM) annual meeting, Orlando, FL (United States), 19-22 Jul 1992
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RADIOACTIVE WASTES
DELAYED NEUTRON ANALYSIS
NUCLEAR MATERIALS MANAGEMENT
ALGORITHMS
CALIFORNIUM 252
CORRECTIONS
MATRICES
NEUTRON FLUX
SAFEGUARDS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CALIFORNIUM ISOTOPES
CHEMICAL ANALYSIS
EVEN-EVEN NUCLEI
HEAVY NUCLEI
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MANAGEMENT
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MATHEMATICAL LOGIC
NONDESTRUCTIVE ANALYSIS
NUCLEAR REACTION ANALYSIS
NUCLEI
RADIATION FLUX
RADIOACTIVE MATERIALS
RADIOISOTOPES
SPONTANEOUS FISSION RADIOISOTOPES
WASTES
YEARS LIVING RADIOISOTOPES
055001* - Nuclear Fuels- Safeguards
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400101 - Activation
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Radiometric & Radiochemical Procedures