Radiotracers for interwell purposes are often purchased from a commercial company as an aqueous solution, sometimes as a dry salt. Whenever the radiotracer can be purchased in dry form this is preferred because it enhances the shelf life of the tracer due to reduced autoradiolysis.

The radiotracers are provided in suitable transport containers which depend on characteristics of the radioisotopes. In most of cases, the supplied radiotracers

are ready for injection, and transported to injection sites according to transportation regulations [21].

In the case of exclusively beta emitting tracers, for instance HTO and S14CN-, it is advantageous to add a small quantity of a short lived gamma emitter in the form of a water tracer, for instance 131I-, for easy monitoring of the injection process during field operation.

Figure 5 shows an example of container for transportation and flow through injection of beta emitting tracers. It has a volume of 100 mL and is rated to a pressure of 350 bar.

The container in its plastic and lead support is mounted inside a transportation drum lined with shock absorbant material, as shown in Fig. 6. The transportation drum is labelled with the correct radioactivity transportation index and information about the type and quantity of the radionuclide according to the national regulations.