4. DISTINGUISHING BETWEEN CHEMICAL FORMS OF TRITIUM

Tritium may be present in elemental form such as HT, DT or T2, or it may be found in its oxide form HTO, DTO or T2O. Since the liquid form is chemically identical to ordinary water, it is easily retained by the body. In its gaseous form, it is almost entirely expelled by the lungs and is not absorbed. Therefore, the oxide form is much more dangerous as a biological hazard.

Consequently, it is important to be able to determine the presence of only the oxide fraction of tritium or to be able to measure the relative quantity of the oxide and the elemental forms. To measure tritium oxide only, the following method can be used. A desiccant system, using drier columns, is interposed between two ionization chambers of identical volume. The ionization chambers are polarized with opposite voltages, so that the net ionization current collected from both ionization chambers will then represent the contributions of ionization current due only to tritium oxide. It is to be noted that this method applies also for true tritium oxide measurements, even when other gaseous radionuclides are present in the sample stream.

To measure the tritium fraction due to elemental tritium only a similar method can be used by first oxidizing the elemental tritium by means of small catalytic converter.

 

5. DISTINGUISHING TRITIUM IN THE PRESENCE OF OTHER RADIOISOTOPES

General environmental air monitoring. The planet we inhabit is naturally radioactive. When measuring tritium in the air we breathe, it is necessary to distinguish it from other radioactive factors such as naturally occurring radon and background gamma radiation from terrestrial or cosmic origin. This is accomplished by using radon alpha pulse suppression and by the use of dual ionization chambers as described above.

 

Continue