Radioactive fallout leads to the collection of radioactive materials in the sea and in freshwater environments, whether by direct deposition or by the outflow of such materials from land to sea or into freshwater sources. Such contamination may also derive from radioactive wastes resulting from nuclear energy operations.
Radioactivity was perhaps the first form of global marine pollution. It initially rose from the early post-World War II nuclear weapons tests by the USA in the South Pacific. Transported by stratospheric air currents, the fission products from a sub-aerial nuclear explosion were distributed through the earth's atmosphere and deposited on the earth's surface, mainly in temperate zones.
The total sea-water burden of artificial radio-activity is less than 1% of the natural level in activity units. According to figures published by UNESCO in 1977, the contributions from nuclear explosions in 1970 dominated those from reactor wastes and from the reprocessing of fuels; by the year 2000 they will still be of higher magnitude, assuming atmospheric nuclear testing will continue to take place at the 1968-70 rate. Artificial radio-activity will not be distributed as homogeneously within the ocean system as the two most important naturally occurring radionuclides, potassium-40 and rubidium-87. Higher values of all fall-out species are found in the northern than in the southern hemisphere, as the greater number of nuclear-bomb detonations took place there. Similarly, the higher values of radio-active wastes associated with the production and use of nuclear fuels will be found in marine waters near the waste discharge sites. In such cases the levels of a given isotope are far in excess of the open sea values where entry has been primarily from atmospheric fallout.
The seas around Russia -- from the Baltic to the Pacific -- are reputedly littered with decaying hulks of nuclear submarines and rusting metal containers with tens of millions of tons of nuclear waste. In 1999 a Norwegian funded project was completed in Northern Russia to stop a brook from streaming through an old storage building for spent nuclear fuel located in Andreeva Bay, Kola Peninsula. The brook was carrying radioactivity out into the Litsa Fjord. In Andreeva Bay there is the largest and the only operational storage facility for spent nuclear fuel in the Northern Fleet.
In Severodvinsk, Northern Russia, Norwegian companies managed a project to upgrade the so-called 'object 159' at Zvezdochka shipyard in Severodvinsk. The object consists of two type A-02 tanks for low-active liquid waste, each with a capacity of 500 cubic meters. The tanks are located near the planned liquid waste processing facility and will serve as a buffer. The upgrade began in May 1998 and was completed as planned in August 1999. Norway provided the $4,3 million required for the project.