Accurate plutonium waste measurements using the {sup 252}Cf add-a- source technique for matrix corrections [electronic resource].

Published: Washington, D.C. : United States. Dept. of Energy, 1992.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description: 4 pages : digital, PDF file
Additional Creators: Los Alamos National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary

We have developed a new measurement technique to improve the accuracy and sensitivity of the nondestructive assay (NDA) of plutonium scrap and waste. The 200-ℓ drum assay system uses the classical NDA method of counting passive-neutron coincidences from plutonium but has added the new features of ``add-a-source`` to improve the accuracy for matrix corrections and statistical techniques to improve the low-level detectability limits. The add-a-source technique introduces a small source of ²⁵²Cf (10{sup −8} g) near the external surface of the sample drum. The drum perturbs the rate at which coincident neutrons from the ²⁵²Cf are counted. The perturbation provides the data to correct for the matrix and plutonium inside the drum. The errors introduced from matrix materials in 200-ℓ drums have been reduced by an order of magnitude using the add-a-source technique. In addition, the add-a-source method can detect unexpected neutron-shielding material inside the drum that might hide the presence of special nuclear materials. The detectability limit of the new waste-drum assay system for plutonium is better than prior systems for actual waste materials. For the in-plant installation at a mixed-oxide fabrication facility, the detectability limit is 0.73 mg of {sup 24O}Pu (or 2.3 mg of high-burnup plutonium) for a 15-min. measurement. For a drum containing 100 kg of waste, this translates to about 7 nCi/g. This excellent sensitivity was achieved using a special low-background detector design, good overhead shielding, and statistical techniques in the software to selectively reduce the cosmic-ray neutron background.

Report Numbers

E 1.99:la-ur--92-2120
E 1.99: conf-9207102--43
conf-9207102--43
la-ur--92-2120

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Note

Published through SciTech Connect.
09/01/1992.
"la-ur--92-2120"
" conf-9207102--43"
"DE92018980"
Institute of Nuclear Materials Management (INMM) annual meeting,Orlando, FL (United States),19-22 Jul 1992.
Menlove, H.O.

Funding Information

W-7405-ENG-36

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