Characterization, Control and Accounting

DOE-HDBK-1132-99

Provisions should be made for crucibles and molds removed or no longer

serviceable to be processed to recover or remove residual plutonium

before they are discarded.

Design should provide for the need to process plutonium scrap and

residue before any subsequent disposition action is taken. Aqueous

(chloride or nitrate system) and pyrochemical processing are required.

Stabilization optimally involves separation of plutonium from matrix

material in order to minimize the volume of material to be stored.

Likewise, separation of plutonium from waste matrices will minimize the

amount of transuranic waste to be shipped and placed in a waste

repository. The final form of the concentrate should be a stable (but not

necessarily highly purified) oxide or metal. The process includes acid

dissolution (hydrochloric or nitric), some degree of purification (e.g., ion

exchange), precipitation (typically as oxalate), calcining (to decompose

the oxalate and produce plutonium oxide), and packaging. If a metal form

is required as the end point, the temperature at which the oxalate is

calcined should be kept as low as practical. Metal can be produced by

direct oxide reduction with elemental calcium in a molten salt medium

(calcium chloride). Means to regenerate the calcium chloride salt medium

should be included in the process design.

Characterization, Control and Accounting . Chemical sampling and analyses

should be provided to support process and operations in the process area of the

PPHF. Techniques employed for the characterization of plutonium include:

metallography, electron microscope, X-ray diffraction, chemical analysis, thermal

analyses, and isotopic. The most common detection technique employed is the

nondestructive assay detection system, which includes (1) radiation detection

based on alpha, gamma radiation, and neutron activation, and (2) calorimetry,

which measures the heat output of the radioactive materials.

Several pyrochemical processes are likely to be used in plutonium processing.

Molten salt extraction is used to separate americium from plutonium in aged

plutonium items. A " altless"extraction process has been developed at Los

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