Tuesday, November 26, 2019

An Existing Site Policy for Small Nuclear Reactors

Commercial Nuclear sites in the US (Credit: US NRC)

by Marcel F. Williams

Commercial nuclear power currently provides more than 19% of the electricity in the US, and about 53% of America's-- carbon neutral-- electricity. But in combination with renewable energy resources (hydroelectric, wind, solar, etc.), only 36% of America's electricity generation is carbon neutral.

The Palo Verde nuclear site in Arizona is the largest power plant in the United States, generating 3.3 GW (gigawatts) of electricity. But existing nuclear sites can be much larger. The Kashiwazaki-Kariwa nuclear site in Japan has seven  nuclear reactors  with a gross installed capacity of 8,212MW.

There are currently 60 nuclear sites in the US, generating more than 100 GW of electricity.  If all sixty of these existing sites were generating at least 8 GW of electricity then commercial nuclear power could generate 480 GW of carbon neutral electricity (93% of current US electricity production). Combined with current renewable energy production, all of America's electricity could be carbon neutral with a 10% surplus in carbon neutral electricity production.

Global mortality rate for electricity production (Credit: Forbes)
Of course, building new nuclear power plants has been politically and economically difficult  in the US for decades even though commercial nuclear power has the lowest fatality rate of any electric power producing facilities. And even some existing nuclear sites in the US are scheduled for complete decommissioning.  However, a new generation of small nuclear reactors could make it safer and cheaper  for existing nuclear sites in the US to produce substantially more carbon neutral electricity.
X-Ray of NuScale Reactor Assembly (Credit: NuScale)

In Portland, Oregon, a company called NuScale is developing a new type of Small Modular Reactors (SMR) that could be centrally mass produced and transported (in three segments) by truck, rail or by barge practically anywhere in the world.

NuScale's nuclear reactor technology has many advantages:

1. They're inherently safe. The  large surface area to volume of the small 60 MWe reactors doesn't physically allow the nuclear fuel contained in these reactors to ever get hot enough for the fuel to melt.  Even if water is totally evaporated or lost from the reactor, the surrounding air will still provide enough natural cooling for the nuclear material to remain solid. While commercial nuclear power is still the safest way to produce electricity per kilowatt produced,  replacing existing nuclear power plants with NuScale units should increase nuclear safety substantially more. 

2. NuScale would also place their small nuclear reactors underground making them less vulnerable extreme weather conditions or potential acts of terrorism.

3. A power producing facility can operate in packs of up to 12 reactors (720 MWe) so that the plant can continue producing electricity while one or more of the reactors is being removed for refueling

4. A NuScale 720 MWe facility would only require 60 acres (18 hectares) of land. A  wind powered facility that could produce a similar amount of electricity would require  130,000 acres (200 square miles). A centralized solar power plant would require 32 to 54-- square kilometers-- of land in order to equal the electricity production of an 18 hectare 720 MWe NuScale facility.

Notional 18 hectares NuScale 720 MWe site (Credit: NuScale)

Current nuclear power plants require 1.3 square miles for a single 1000 MWe nuclear facility. And most existing nuclear sites were originally designed to accommodate two to four 1000 MWe reactors. So, in theory, the 2.6 to 5.2 square miles in area of current nuclear sites could easily accommodate several 720 MWe NuScale power units. So NuScale facilities could easily produce more than  8000 MWe of electricity at existing nuclear sites in the US.

NuScale nuclear reactor component being transported by rail (Credit: NuScale)

While commercial nuclear power plants produce base load electricity, they have to be complimented with regional  electric power units capable of producing peak load electricity or back up electricity in case a nuclear facility has to be temporarily shutdown because of refueling or because of a natural disaster such as an earthquake or tsunami.

10.7 MWe rated methanol electric power plant at Point Lisas, Trinidad (Credit: Mendenhall Technical Services):

Natural gas electric power plants have the lowest capital cost. But natural gas is a fossil fuel that would increase global warming and the rise of global sea levels. Fortunately, natural gas power plants can be  cheaply and conveniently retrofitted to use-- methanol. And nuclear electricity could be used to produce  methanol directly from air and water or through the microwave pyrolysis of urban garbage and sewage, agricultural biowaste, and from forest waste (dead trees and other fire hazardous forest materials). Methanol dehydrated into dimethyl ether could be used as a diesel fuel substitute for vehicles cheaply retrofitted to use dimethyl ether. Methanol can  be converted into carbon neutral gasoline and carbon neutral jet fuel. Methanol can be used directly a cleaner marine fuel substitute for sea vessels. And methanol can be used directly in fuel cell/battery powered automobiles, trucks, sea craft, and even aircraft.

Methanol powered ferry (Credit: Stena Germanica)

The increased electrical capacity of existing nuclear sites could also be used to produce hydrogen for the next generation of supersonic and hypersonic aircraft and space launch vehicles. Hydrogen could also be used for the carbon neutral production of ammonia for fertilizer for the agricultural industry.
Notional hydrogen fueled hypersonic airliner (Credit: Reaction Engines)

In Arizona, using NuScale reactors to increase  electrical capacity at the Palo Verde site to 8000 MWe (4700 MWe of additional power) could be used to supply more-- carbon neutral-- electricity to  neighboring California and for the Sonora and Baja California provinces of Mexico. Mexico could use the additional power supplied by the US to pump-- seawater-- directly from the Gulf of California into salt water reservoirs near the Arizona/Sonora border. Such seawater reservoirs could be used for the creation of recreational marine water lakes in southern Arizona and for the production of needed potable water through nuclear powered desalination. 

If the US, finally, begins to  recycling at least some of its spent fuel from commercial nuclear sites then it might be politically easier to reopen nuclear sites that have been decommissioned or are scheduled to be decommissioned for the deployment of inherently safe  NuScale reactors.

Existing sites can easily accommodate the relatively tiny amounts of spent nuclear fuel produced at commercial facilities. But some US states have laws preventing the deployment of new nuclear reactors until there is a long term solution for spent fuel. So clearly demonstrating that spent fuel from commercial nuclear reactors can be recycled to produce more energy should nullify any state measures that attempt to use spent fuel as an excuse for not building more nuclear power plants.

The  TVA (Tennessee Valley Authority) is a Federally owned utility that could start the process of recycling spent fuel by utilizing plutonium extracted from spent fuel in thorium fuel configurations in existing nuclear power plants  and in future SMRs.  The TVA should also be one of the first American utilities to deploy the next generation fast reactors that would be fully capable of utilizing spent fuel.

References and Links

 US electricity production in 2018

Top ten nuclear power plants by capacity

NuScale's Small Modular Nuclear Reactor Passes Biggest Hurdle Yet

 How much land does nuclear, solar, and wind really need?

 The Ultimate fast facts guide to nuclear energy

Land needs for wind, solar dwarf nuclear power plant's footprint 

 Producing renewable jet fuels from methanol

Utilizing renewable methanol to power electric commuter aircraft

Methanol as a marine fuel 

Renewable methanol as liquid electricity

Serenergy's 800 kilometer plugin hybrid methanol fuel cell car

Thor and the thorium solution for plutonium from commercial nuclear reactors

LAPCAT A2 hypersonic hydrogen fueled airliner

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