Fire - doe-std-1136-20040046

DOE-STD -1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

machining chips. Care must be taken to ensure that H2 generated in this manner does not accumulate (in

closed drums or storage containers for example).

2.6.4 Fire

Finely divided uranium metal is highly reactive or pyrophoric, capable of igniting spontaneously.

This type of material should be handled and stored in a manner that minimizes fire potential. Typically,

machining chips are stored under water or machining oil in open storage containers so that any H2 generated

does not accumulate. Neither water spray, CO2, nor halon extinguishers are effective in fighting uranium

fires. In fact, halon may be explosive if directed at burning uranium and can produce very toxic fumes and

gases. Small uranium fires can be smothered in MET-L-X powder (a mixture of sodium chloride and

potassium carbonate). Larger fires, involving drums of machining turnings, for example, can be controlled

by immersing the burning container in water. Even this will not immediately extinguish the fire because the

hot uranium metal dissociates the water into H2 and O2, providing fuel and oxygen for the fire. If the

quantity of water is sufficient, eventually the water will provide enough cooling to extinguish the fire, but a

significant amount of water can boil away in the process. If the water level is allowed to fall low enough to

uncover the uranium while the fire is still burning, it will resume burning visibly. DOE-HDBK-1081-94,

Primer on Spontaneous Heating and Pyrophoricity, (DOE 1994e) contains additional guidance.

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