Accurate plutonium waste measurements using the sup 252 Cf add-a- source technique for matrix corrections
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-{ell} 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 {sup 252}Cf (10{sup {minus}8} g) near the external surface of the sample drum. The drum perturbs the rate at which coincident neutrons from the {sup 252}Cf 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-{ell} 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.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 7066870
- Report Number(s):
- LA-UR-92-2120; CONF-9207102-43; ON: DE92018980
- 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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PLUTONIUM 240
NEUTRON DETECTION
RADIOACTIVE WASTES
RADIOASSAY
ACCURACY
CALIBRATION
CALIFORNIUM 252
CONTAINERS
CORRECTIONS
NEUTRON DETECTORS
NONDESTRUCTIVE ANALYSIS
NUCLEAR MATERIALS MANAGEMENT
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ALPHA DECAY RADIOISOTOPES
CALIFORNIUM ISOTOPES
CHEMICAL ANALYSIS
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HEAVY NUCLEI
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MANAGEMENT
MATERIALS
MEASURING INSTRUMENTS
NUCLEI
PLUTONIUM ISOTOPES
RADIATION DETECTION
RADIATION DETECTORS
RADIOACTIVE MATERIALS
RADIOISOTOPES
SPONTANEOUS FISSION RADIOISOTOPES
WASTES
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