Posted By John Donaldson Gary So far as Road Transport in the UK is concerned you need to look at the Radioactive Material (Road Transport)(Great Britain) Regulations 1996 SI 1350. Just to complicate maters the Regulations then refer to the regulations covering transport by rail for some of the definitions. Air transport is best referred to one of the specialist air cargo handlers as it can differ between airlines and the destination country. One other matter you will need to consider is registration with the Environment Agency under the Radioactive Substances Act 1993 if you are not already registered. I am presuming the CS-137 isotope you are referring to is a closed source and part of an analytical instrument. If you are intending to use it in the field you will also need a mobile source authorisation. To complicate matters further the EA authorisation only covers England if you intend to use it in Scotland you will need to register with SEPA. The activity you quote 350 Bq looks very low for a source I would have expected it be in the order of 350 kBq could I suggest you check this figure again. The activity will make a significant difference to how you transport it. I have given a quick overview but in all matters relating to the use of radioactive materials you must refer this to the RPA appointed under the Ionising Radiation Regulations 1999.