ANALYSIS OF TRITIUM AND 3He TRACKS USING A MASS SPECTROMETER AND PROPORTIONAL COUNTER.

Tritium (T) is incorporated in materials stored in the presence of a background tritium source, and the same is true for **3He, which is produced from tritium by beta decay. The processes responsible for sample contamination are elucidated. Measurements of **3He and **4He using a magnetic resonance mass spectrometer and a T-proportional counter revealed that dust particles carrying tritium (T) and **3He are the cause of the contamination. When tritium is presented in the laboratory as a component of gaseous molecules, almost all of the tritium adheres to the large, exposed surface of the dust particles and remains there for extended periods. The concentration of T and **3He in dust particles is measured, and it is established that the rate of helium-3 evolution during dynamic annealing is a maximum at 250 degree C, which is much less than the temperatures at which **3He is evolved for other typical naturally occurring samples. The **3He evolution curve thus gives information regarding the level of contamination by T** minus and **3He-bearing dust particles. It is also established that **3He is retained longer in dust particles than T, so that tritium leakage into the laboratory over extended periods of time can be detected by measuring the **3He concentration or the ratio **3He/**4He.