Nuclear powered submarines as hazards for the marine environment

Hundreds of nuclear-powered submarines (NPS) have been manufactured since 1953; some 160 are still in operation. Decommissioning NPS is a major, delicate and costly task. There have been many incidents with NPS during their 50 years operational period: Most of these emergencies resulted in serious radiological and ecological consequences. In the Mediterranean, the effects of marine pollution due to NPS have been under recent investigation following the October 2003 accident to the US nuclear submarine Hartford in Sardinia (Italy). Preliminary studies indicated that no apparent environmental release had taken place as a direct result of the accident. However, further analyses detected traces of Pu-239 in several of the algal species, indicative of anthropogenic pollutants. Furthermore, several samples showed concentrations of radially distributed alpha tracks (forming “hot spots”) emanating from micron-sized point sources. The concentrated, extremely localized occurrence of these nuclides cannot be explained in terms of left-over worldwide nuclear pollution. A local source seems more plausible. Our ongoing sampling programme has revealed that: some of the high alpha/hot spot levels measured in February 2004 have decreased markedly during subsequent months, others have decreased only slightly, and others still have remained unchanged: a clear indication that different nuclides are present. We are now analyzing 2005 samples.