Niobium and tantalum raw materials can contain low levels of thorium (Th) and uranium (U), which leads to these raw materials being treated as naturally occurring radioactive materials (NORM). The determination of whether a material is or isn’t radioactive for all purposes, including transport, is based on guidance issued by the International Atomic Energy Agency (IAEA), although occasionally regulations in individual countries vary from this.
For transport, the IAEA specifies that when the radioactivity concentration is above 10 becquerels per gram (10 Bq/g) a material must be transported as a radioactive material, and based on this the various United Nations regulations on modal transport describe this as Class 7 Dangerous Goods. For tantalum and niobium raw materials the Bq/g level can be determined from the levels of Th and U (or ThO2 and U3O8) in the assay results.
Throughout this website the figures quoted in Bq/g refer to the relevant (parent) nuclide only, in accordance with the values listed in the IAEA regulations SSR-6 of 2012, which have remained unchanged since first introduced in 1996. The conversion factors applied are as follows:
• 1% ThO2= 35.6 Bq/g (1% Th = 40.6 Bq/g)
• 1% U3O8= 104 Bq/g (1% U = 123 Bq/g)
For further information on Class 7, NORM, Bq/g and to read the T.I.C.’s policy please visit the Transport page.