The radioactive and toxic by-products of the nuclear-energy and nuclear-weapons industries. Nuclear waste may have an active life of several thousand years. Reactor waste is of three types: high-level spent fuel, or the residue when nuclear fuel has been removed from a reactor and reprocessed; intermediate, which may be long- or short-lived; and low-level, but bulky, waste from reactors, which has only short-lived radioactivity. Disposal, by burial on land or at sea, has raised problems of safety, environmental pollution, and security. In absolute terms, nuclear waste cannot be safely relocated or disposed of.
The issue of nuclear waste is becoming the central controversy threatening the future of generating electricity by nuclear energy. The dumping of nuclear waste at sea officially stopped 1983, when a moratorium was agreed by the members of the London Dumping Convention (a United Nations body that controls disposal of wastes at sea). Covertly, the USSR continued dumping, and deposited thousands of metric tons of nuclear waste and three faulty reactors in the sea 1964–86. The USSR and the Russian Federation between them dumped an estimated 12 trillion becquerels of radioactivity in the sea 1959–93. Russia has no way of treating nuclear waste and in 1993 announced its intention of continuing to dump it in the sea, in violation of international conventions, until 1997. Twenty reactors from Soviet nuclear-powered ships were dumped off the Arctic and Pacific coasts 1965–93, and some are leaking. Fish-spawning grounds off Norway are threatened by plutonium from abandoned Soviet nuclear warheads.