Use of Nuclear Energy for Desalination

Seawater desalination is the best way to meet increasing demands of freshwater because it can produce freshwater with necessary quality by choosing an appropriate desalination process and post-treatment methods of the product water.

Most desalination is accomplished through a process called reverse osmosis (RO), which pressurizes seawater and forces it through a membrane against its osmotic pressure, extracting the salt. A second process, called multi-stage flash distillation, uses a steam-based process to filter salt and other minerals. It has proven less cost-effective than reverse osmosis even though it produces purer water. 

The cost, degree of availability, heaviness of the duty, and the required purity selection of the appropriate desalination technology between evaporation and reverse osmosis is grounded on several factors, including investment cost, maintenance of the desalinated water.

Nuclear desalination is the using of excess heat from a nuclear power plant to evaporate sea water and extract salts from seawater to produce drinkable fresh water or using produced electricity in RO technology. The main energy sources for future desalination are nuclear power reactors and renewable energy sources such as solar, hydro, or wind, but only nuclear reactors are capable of delivering the copious quantities of energy required for large-scale desalination projects.

The seawater desalination plant designs for nuclear plant coupling- are identical to those of fossil plant coupling, with exception of desalination plants using RO technology, which in the case of a nuclear desalination plant, the plastic casings of RO membranes are covered with carbon steel.
A nuclear co-generation desalination plant consists of three interacting systems: nuclear steam supply system (NSSS), the turbine generator system and the desalination unit. 

Small and medium sized nuclear reactors are suitable for desalination, often with cogeneration of electricity using low-pressure steam from the turbine and hot seawater feed from the final cooling system. The main opportunities for nuclear plants have been identified as the 80-100,000 m³/day and 200-500,000 m³/day ranges.

There are 53 operational nuclear power plants in Japan as of December 2000, which are located in coastal areas in order to use seawater as an ultimate heat sink.

Finally; Tunisia sponsored research on the topic and found that costs for nuclear-powered desalination were about a third to a half less than using fossil fuels, depending on the desalination technology used.