Reconstruction of gaseous tritium waste from the Cea centre facilities at Saclay using rings from two trees over 50 years old

The monitoring of gaseous discharges of tritium from nuclear facilities CEA Saclay is ensured consistently since 1968, roughly coinciding with the arrival on the market of liquid scintillation counters for serial measurements. 1968 is precisely the year when the highest releases of tritium have been measured. So it was interesting to estimate releases from previous years, since late 1952 which is the year of entry into operation of the first facilities of the research center. Indeed, emissions higher than in 1968 could have occurred during this period. The history of gaseous tritium releases have been reconstructed from tree rings of two trees over 50 years collected in two separate locations within the site, on its outskirts. This reconstruction shows that only 3 years prior to 1968 may have had higher emissions than in 1968 (about 40% more). Before 1965, emissions were much lower and consistent with the studies and research programs that were making use of smaller amounts of tritium. The first releases of tritium gas are also coherent with the history of researches made using this radionuclide in Saclay, which started around 1959. (author)