United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No.80-25 – Transportation of Pyrophoric Uranium

                                                           SSINS No.:  6870 
                                                           Accession No.:  
                                                           8005050046      

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                          WASHINGTON, D.C. 20555  
                                     
                               May 30, 1980  

                                           Information Notice No. 80-25 

TRANSPORTATION OF PYROPHORIC URANIUM 

Background 

From time to time NRC has received reports of transportation incidents 
involving the shipment of uranium in a pyrophoric form (capable of 
spontaneous ignition). These forms generally include finely divided metallic
saw turnings and chips, sawdust, and abrasive saw sludge.  Moisture in the 
form of water or machining coolants is usually present on the finely divided
material, contributing to its reactivity due to the radiolytic decomposition
of the water reacting with the base metal to create hydrogen gas. Hydrogen 
gas generation and reactivity will vary with the particle size (surface area
to volume ratio) of the fines, free moisture content, and age of the 
material. Although the exact reaction kinetics of finely divided pyrophoric 
metals is not well understood, past industry experience has indicated that 
extreme care must be exercised in the proper storage and transportation of 
such pyrophoric forms of uranium so as to preclude spontaneous ignition. 

Fires resulting are extremely difficult to extinguish using such convential 
fire extinguishing agents as CO2, foam, and dry chemical.  Water, if used in
very large volumes or by total immersion can be effective. Water used as a 
fine spray, however, can be extremely dangerous, actually causing a more 
violent reaction due to the radiolytic breakdown of the water from the 
extremely high temperatures.  Further, such fires also create an inhalation 
hazard due to the dispersion of airborne uranium as particulate matter. 

Transportation Regulations 

Although the Department of Transportation (DOT) regulations in 49CFR do not 
provide specific provisions for packaging and shipment of pyrophoric 
uranium, in 49 CFR 172.101, there does appear a proper shipping name:  
"Uranium metal, pyrophoric", under the radioactive material hazard class. 
This indicates that such materials are to be labelled as both a radioactive 
material and a flammable solid. Under the column "packaging", SS172.101 then 
makes reference to the requirements for low specific activity and fissile 
radioactive materials. The only other relevant provision of 49CFR, albeit, a 
very important one is 49 CFR 173.21(b): under "Prohibited packaging", which 
reads: 

"(b) the offering of any package or container of any liquid solid or gaseous
material which under conditions incident to transportation may polymerize 
(combine or react with itself) or decompose so as to cause dangerous 
evolution of heat or gas is prohibited.  Such materials may be offered for 
transportation when properly stabilized or inhibited. Refrigeration may be 
used as a means 
.

Information Notice No. 80-25                                May 30, 1980 
                                                               Page 2 of 3 

of stabilization only when approved by the Bureau of Explosives".  However, 
the DOT regulations require no specific methods of stabilization of 
pyrophoric uranium prior to shipment. 

Shipping Practices 

In the earlier years of the nuclear industry many shippers offered 
pyrophoric uranium for transportation in steel drums, in which the turnings, 
chips or sludge was submerged under mineral oil. This method has the 
distinct safety problem of allowing a pressure buildup of hydrogen gas 
within the drum. This may cause a personnel hazard upon opening the drum, 
and a possible explosive release and/or ignition of the hydrogen gas. In 
some cases, venting devices have been used or holes have been drilled in 
drum lids to allow continuous venting of hydrogen gas. However, this poses 
problems also, especially in confined or closed spaces, such as a closed 
highway van. 

Currently, most shippers of pyrophoric uranium have elected not to transport
such materials submerged under oil. Instead, one the following alternatives 
is used: 

1.   Conversion of the material to a non-pyrophoric material in a oxide form
     by incineration prior to shipment. 

2.   Mixing of the pyrophoric material in a hardened matrix of concrete, 
     with a high concrete to turnings ratio. Such mixing appears to 
     stabilize the material so as to preclude any significant gas 
     generation. 

3.   Mixing of the pyrophoric material in a solidified plaster-of-paris type
     matrix. (This method may not eliminate gas generation and may not 
     sufficiently "stabilize" the material. A shipment of such material was 
     involved in a May 14, 1979 incident at the Beatty, Nevada waste burial 
     facility. During this incident fire destroyed a vehicle containing such
     uranium wastes, along with other wastes containing flammable 
     scintillation fluids. The exact cause of the fire is uncertain, 
     however, the extremely reactive nature of the pyrophoric materials 
     present undoubtedly contributed to the severity of the fire). 

Proposed DOT Regulations 

In order to more clearly specify safety provisions for packaging and 
transport of pyrophoric materials, DOT has recently proposed (Jan 8, 1979 44
F.R. 1852, Part II) new criteria for description, classification and 
packaging of "pyrophoric radioactive materials". These proposed criteria are
quoted in Enclosures 1 & 2. 

Summary 

In view of the above, NRC licensees who generate pyrophoric forms of uranium
in their licensed operations are cautioned to carefully consider the 
requirements of 49 CFR 173.21(b) to properly "stabilize" such materials 
prior to 
.

Information Notice No. 80-25                                May 30, 1980 
                                                               Page 3 of 3 

offering them for transport. The methods which have apparently been the most
satisfactory are: 

1.   Incineration to a non-pyrophoric oxide (will require specific approval 
     pursuant to 10 CFR 20.305); or 

2.   Mixing and solidifying in a large matrix of concrete. 

Questions about this Information Notice can be directed to NRC Headquarters,
Office of Inspection and Enforcement, Division of Fuel Facilities and 
Materials Safety Inspection, Washington, D.C. 20555 (Attn: Sr. 
Transportation Specialist) 301-492-8188. 

Page Last Reviewed/Updated Tuesday, November 12, 2013