DETERMINATION OF PLUTONIUM RADIOACTIVITY IN MURUROA LAGOON WATER

This study presents the plutonium radioactivity levels measured in Mur uroa lagoon water during the 1985-1998 period. The low radioactivity l evels recorded, from 10(-2) to 1.5 BQ/m(3) are due to the slow solubil ization of plutonium deposited in lagoon sediments following atmospher ic experiments which took place from 1966 to 1974. The average concent rations of the lagoon water tend to decrease from one year to the next . However, the influence of the weather conditions is discussed. The M ururoa lagoon being open to the ocean, plutonium radioactivity traces are still detectable in the immediate vicinity of the atoll.