[ RadSafe ] Tritium questions

[Jim Otton]

Radsafers,
We are investigating a landfill in the southwestern U.S. open from the 1950s
to the 1990s.  Elevated tritium occurs in water in the landfill (445 TU) and
just downgradient from it (16TU). Further downgradient levels drop to about
0.5 TU.
Possible sources could include bomb-pulse tritium (site is downwind from the
Nevada Test Site), tritium from exit signs or medical waste, or lithogenic
tritium.
Questions:
When did tritium commonly become used in exit signs?
Are there any medical wastes that contain tritium or could generate tritium?
Does someone have a reference for the Flagstaff IAEA/WMO station tritium
data? We are aware of the Albuquerque station and its data.
What uranium and lithium concentrations are needed to generate significant
lithogenic tritium from the solid phases present in the landfill and
immediately downgradient?

Jim Otton
U.S. Geological Survey