Radiological Safety Training for Uranium Facilities
Module 101 Properties of Uranium
have the same chemical reactivity, and all can be made into the many different
physical and chemical forms discussed in this section.
Uranium is a metal that will sustain a burning reaction (similar to a magnesium
flare). The potential for a fire is greatest when the uranium is in a finely divided
form, such as milling chips or filings. In this form, uranium can undergo
spontaneous ignition. Uranium metal is often machined to provide a useful end
product, and milling chips and filings are unavoidable byproducts.
Precautions must be taken to prevent chips and filings from igniting. One
precaution is submersing the chips and filings in water or a mineral oil. Storage
in water produces hydrogen gas due to a chemical reaction. To prevent the
hydrogen gas from reaching an explosive concentration, and to prevent a
pressure buildup, containers must be vented. Incidents have occurred where
container lids have been blown off by unexpected gas pressure buildup.
Once uranium starts to burn, it is extremely difficult to extinguish. None of the
typical extinguishing methods, such as water, carbon dioxide, or halon, is
effective in fighting uranium fires. In fact, halon may be explosive and produce
toxic fumes if used directly on the fire. Normally, small fires may be put out by
using MET-L-X powder, which is a mixture of sodium chloride (table salt) and
potassium carbonate (baking powder). When spread over the burning metal in
significant quantities, MET-L-X starves the fire of oxygen.
Larger fires, such as with storage drums, are more difficult to extinguish.
Submersion in water will eventually work once the metal cools down. However,
continuous water addition is necessary to make up for losses due to boiling and