Refueling submarines can take more than two years because they get stuck behind aircraft carriers, he said. Nuclear power plants on board submarines are the most expensive and difficult to maintain due to limited space. In the United States Navy, refueling and reconditioning (ROH) refers to a lengthy reconditioning process or procedure performed on nuclear-powered naval vessels, involving the replacement of spent nuclear fuel with new fuel and general maintenance repair, refurbishment, and often modernization of the entire ship. In theory, such a process could simply involve just refueling or just a review, but in practice, nuclear refueling is always combined with a review.
An ROH usually takes one to two years for submarines and up to almost three years for an aircraft carrier, made in a naval shipyard. Time periods between RoHS on a ship have historically varied from approximately 5 to 20 years (for submarines) to 25 years (for Nimitz class aircraft carriers). For modern submarines and aircraft carriers, RoHs are generally carried out about half their useful life. There are also shorter maintenance arrangements called availability for ships periodically in the shipyards.
A particularly lengthy refueling, maintenance and modernization process for a nuclear aircraft carrier can last up to almost three years and is known as a refueling complex (RCOH) overhaul. This was the first RCOH for the Nimitz class and only the fourth achieved on a nuclear aircraft carrier. At the end of the Cold War, in 1989, there were more than 400 nuclear-powered submarines in operation or under construction. Because it is so radioactive, removing a nucleus with spent nuclear fuel from a reactor requires elaborate radiological handling precautions.
The dismantling of nuclear-powered submarines has become an important task for both the United States and Russia. Discharges of rare earth elements formed as fission products by thermal neutrons during nuclear power production are not as well studied. Other more localized sources of 137C in the marine environment include the consequences of the Chernobyl accident (UNSCEAR, 2000) and routine operations of nuclear power plants (as a component of low-level radioactive liquid effluents). Department of Energy (DOE) discards some types of contaminated reactor parts from nuclear ships at Hanford facility in Washington State.
Although most nuclear-powered vessels are submarines, they range in type from icebreakers to aircraft carriers. On the contrary, nuclear propulsion has proven to be technically and economically feasible in the Soviet Arctic. The nuclear reactors that power some aircraft carriers typically consume their nuclear fuel at about half of their desired 50-year lifespan. An example of the renovation work done during submarine refueling and overhauls is the conversion of a fleet ballistic missile (SSBN) submarine to a guided missile submarine (SSGN).
The power and energy levels needed to break the ice, along with the difficulties of refueling other types of vessels, are important factors. For use in shallow waters, such as estuaries and rivers, Taymyry-class shallow draft icebreakers with a reactor are being built in Finland and equipped with its nuclear steam supply system in Russia. Naval Nuclear Transportation Oregon Department of Energy This webpage provides information on transporting decommissioned naval nuclear reactors. With the increasing attention paid to greenhouse gas emissions from the burning of fossil fuels for international air and sea transport and the excellent safety record of nuclear-powered vessels, it is quite conceivable that renewed attention will be paid to marine nuclear propulsion.