H-3 in drinking water

["Pilt, Aadu" <Aadu.Pilt@jus.gov.on.ca>]

According to Ontario Hydro, background tritium concentrations for Lake
Ontario are 8.7 Bq/L and for Lake Huron, 9.1 Bq/L.

Since CANDU nuclear generating stations use heavy water (D2O) and
deuterium absorbs neutrons to become tritium, any releases of moderator
or heat transport D2O the the lake will contain tritium.

Actual tritium levels at water supply plants near Ontario Hydro
generating stations are from 1-20 Bq/L above background.

The Interim Ontario Drinking Water Objective is the internationally
recommended 7,000 Bq/L.

Accidental process system failures in 1992 and 1996 resulted in releases
of tens of thousands of Curies of tritiated heavy water to Lake Ontario.
In no instance was the concentrations at the intake greater than 1,500
Bq/L. Nevertheless, a Provincial response was initiated, consisting of
monitoring, sampling and analysis. Several Provincial ministries and
Ontario Hydro, with this office as the lead agency, were involved in
this response.

Hope this helps.

Dr A A Pilt
Emergency Measures Ontario

aadu.pilt@jus.gov.on.ca