Nuclear Power Confronts Scarce Water

Water and Improved Nuclear Energy

Existing nuclear reactors often use large amounts of water and often feature the characteristic shaped cooling towers that cool the water traditional LWR reactors need to remove heat from the reactor core. Unfortunately water is not infrequently a scarce resource in many communities around the Country. What may not be widely known is the fact that the requirement for significant amounts of cooling water is not unique to nuclear reactors but applies equally to Solar Thermal, Natural Gas, and Coal Fired Power Plants. The requirement for cooling water is primarily the result of the power turbine that is common to all of these power generation technologies and is used to transform heat energy into electrical energy.

To achieve good thermodynamic efficiency and to efficiently produce electrical power it is typically necessary to cool the outlet leg of nuclear, solar thermal, natural gas, and coal fired power plant turbines. The need for cooling water is essentially equal in all of these power generation technologies and is not greater for nuclear energy relative to Solar Thermal or any of the other competitive technologies on a per Megawatt of electrical power output basis. If a nuclear reactor and a Solar Thermal power plant both produce 100 MWatts of electrical power they will both have essentially the same demand for cooling water because they both are using a common technology turbine-generator which has equivalent requirement for cooling the outlet leg of the turbine to achieve good power conversion efficiencies. Locating adequate amounts of cooling water is a vital requirement for plans for not only nuclear but also solar thermal, natural gas, and coal fired power plants, all which use turbine generators to finally convert heat into electricity. Power plant projects for all of these technologies sometimes have to be put on hold because it is not possible to provide both the water needed for communities and agriculture as well as sufficient cooling water for energy production.

We really can build better nuclear plants [1] that make less nuclear waste and require less cooling water. This nuclear technology is not new and was proven to work at Oak Ridge National Laboratory 40 years ago. This technology is called a Liquid Fluoride Thorium Reactor (LFTR) and it burns much more abundant Thorium nuclear fuel. ORNL built and operated a successful LFTR prototype reactor between 1965 and 1969. This technology is superior to conventionally deployed Light Water Reactor nuclear technology used in the United States and produces in excess of 100 times less nuclear waste [2] and can be built to not require any cooling water (condenser dry cooling) which helps preserve precious water resources.

Liquid Fluoride Molten Salt Reactors (LFTRs) tend to operate at higher temperatures and because of this can be built to not require any water for cooling the core (the molten salt is a very effective and safe core coolant that has good safety promoting properties like carrying away large amounts of heat without boiling or producing high pressures inside the reactor – even under extreme circumstances and during high temperature events). Like modern submarines, LFTRs can use closed Brayton cycle turbine machinery where no steam is released into the environment while the turbine transforms the heat produced in the fluid fueled nuclear reactor into electricity. For reactors like LFTR that can safely operate at high temperature (~800 degrees C) air cooled condensers can dissipate all of the heat pr