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The Nuclear Fuel Cycle

presented to

“The Role of Nuclear Power”

Summer Workshop

Washington and Lee University

and The Council on Foreign

Relations

Lisa Gordon-Hagerty

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The Nuclear Fuel Cycle

• The nuclear fuel cycle is the series of industrial processes which involve the production of electricity from uranium in nuclear power reactors.

• Uranium is a relatively common element that is found throughout the world. It is mined in several countries and must be processed before it can be used as fuel for a nuclear reactor.

• Electricity is created by using the heat generated in a nuclear reactor to produce steam and drive a turbine connected to a generator.

• Fuel removed from a reactor, after it has reached the end of its useful life, can be reprocessed to produce new fuel or stored for future disposal.

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FRONT END AND BACK END….

The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing

stages.

• FRONT END: the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and

• BACK END: safely manage, contain, and either reprocess or dispose of spent nuclear fuel.

If spent fuel is not reprocessed, the fuel cycle is referred to as a open fuel cycle (or a once-through fuel cycle). If the spent fuel is reprocessed, it is referred to as a closed fuel cycle.

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Uranium

• URANIUM is a slightly radioactive metal that occurs throughout the earth's crust. It is about 500 times more abundant than gold and about as common as tin. It is present in most rocks and soils as well as in many rivers and in sea water. It is, for example, found in concentrations of about four parts per million (ppm) in granite, which makes up 60% of the earth's crust. In fertilizers, uranium concentration can be as high as 400 ppm (0.04%), and some coal deposits contain uranium at concentrations greater than 100 ppm (0.01%). Most of the radioactivity associated with uranium in nature is in fact due to other minerals derived from it by radioactive decay processes, and which are left behind in mining and milling.

• There are several areas around the world where the concentration of uranium in the ground is sufficiently high that extraction of it for use as nuclear fuel is economically feasible. Such concentrations are called ore.

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Uranium MiningBoth excavation and in situ techniques are used to recover uranium ore.

• Open pit mining is used where deposits are close to the surface and underground mining is used for deep deposits, typically greater than 120m deep. Open pit mines require large holes on the surface, larger than the size of the ore deposit, since the walls of the pit must be sloped to prevent collapse. As a result, the quantity of material that must be removed in order to access the ore may be large. Underground mines have relatively small surface disturbance and the quantity of material that must be removed to access the ore is considerably less than in the case of an open pit mine.

• An increasing proportion of the world's uranium now comes from in situ leaching (ISL), where oxygenated groundwater is circulated through a very porous orebody to dissolve the uranium and bring it to the surface. ISL may be with slightly acid or with alkaline solutions to keep the uranium in solution. The uranium is then recovered from the solution as in a conventional mill.

• The decision as to which mining method to use for a particular deposit is governed by the nature of the orebody, safety and economic considerations.

• In the case of underground uranium mines, special precautions, consisting primarily of increased ventilation, are required to protect against airborne radiation exposure.

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Uranium Milling• Milling, which is generally carried out close to a uranium mine,

extracts the uranium from the ore. Most mining facilities include a mill, although where mines are close together, one mill may process the ore from several mines. Milling produces a uranium oxide concentrate which is shipped from the mill. It is sometimes referred to as 'yellowcake' and generally contains more than 80% uranium. The original ore may contains as little as 0.1% uranium.

• In a mill, uranium is extracted from the crushed and ground-up ore by leaching, in which either a strong acid or a strong alkaline solution is used to dissolve the uranium. The uranium is then removed from this solution and precipitated. After drying and usually heating it is packed in 200-litre drums as a concentrate.

• The remainder of the ore, containing most of the radioactivity and nearly all the rock material, becomes tailings, which are emplaced in engineered facilities near the mine (often in mined out pit). Tailings contain long-lived radioactive materials in low concentrations and toxic materials such as heavy metals; however, the total quantity of radioactive elements is less than in the original ore, and their collective radioactivity will be much shorter-lived. These materials need to be isolated from the environment.

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2005 Uranium Mining Statistics

• 17 countries produced concentrated uranium oxides• Canada 27.9%• Australia 22.8% • Kazakhstan 10.5%• Russia 8.0%• Namibia 7.5%• Niger 7.4%• Uzbekistan 5.5%• United States 2.5%• Ukraine 1.9%• China 1.7%

The ultimate supply of uranium is believed to very large and sufficient for at least the next 85 years. It is estimated that for a ten-fold increase, the supply of uranium that can be economically

mined is increased 300 times.

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Conversion

• The product of a uranium mill is not directly usable as a fuel for a nuclear reactor. Additional processing, generally referred to as enrichment, is required for most kinds of reactors. This process requires uranium to be in gaseous form and the way this is achieved is to convert it to uranium hexafluoride, which is a gas at relatively low temperatures.

• At a conversion facility, uranium is first refined to uranium dioxide, which can be used as the fuel for those types of reactors that do not require enriched uranium. Most is then converted into uranium hexafluoride, ready for the enrichment plant. It is shipped in strong metal containers. The main hazard of this stage of the fuel cycle is the use of hydrogen fluoride.

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“Yellowcake”

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Enrichment• Natural uranium consists, primarily, of a mixture of two isotopes

(atomic forms) of uranium. Only 0.7% of natural uranium is "fissile", or capable of undergoing fission, the process by which energy is produced in a nuclear reactor. The fissile isotope of uranium is uranium 235 (U-235). The remainder is uranium 238 (U-238).

• In the most common types of nuclear reactors, a higher than natural concentration of U-235 is required. The enrichment process produces this higher concentration, typically between 3.5% and 5% U-235. This is done by separating gaseous uranium hexafluoride into two streams, one being enriched to the required level and known as low-enriched uranium. The other stream is progressively depleted in U-235 and is called 'tails'.

• Two enrichment processes exist in large scale commercial use, each uses UF6 as feed: gaseous diffusion and gas centrifuge. They both use the physical properties of molecules, specifically the 1% mass difference, to separate the isotopes. The product of this stage of the nuclear fuel cycle is enriched uranium hexafluoride, which is reconverted to produce enriched uranium oxide.

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Fuel Fabrication

• Reactor fuel is generally in the form of ceramic pellets. These are formed from pressed uranium oxide which is sintered (baked) at a high temperature (over 1400°C). The pellets are then encased in metal tubes to form fuel rods, which are arranged into a fuel assembly ready for introduction into a reactor. The dimensions of the fuel pellets and other components of the fuel assembly are precisely controlled to ensure consistency in the characteristics of fuel bundles.

• In a fuel fabrication plant great care is taken with the size and shape of processing vessels to avoid criticality (a limited chain reaction releasing radiation). With low-enriched fuel criticality is most unlikely, but in plants handling special fuels for research reactors this is a vital consideration.

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Power Generation

• Inside a nuclear reactor the nuclei of U-235 atoms split (fission) and, in the process, release energy. This energy is used to heat water and turn it into steam. The steam is used to drive a turbine connected to a generator which produces electricity. Some of the U-238 in the fuel is turned into plutonium in the reactor core. The main plutonium isotope is also fissile and it yields about one third of the energy in a typical nuclear reactor. The fissioning of uranium is used as a source of heat in a nuclear power station in the same way that the burning of coal, gas or oil is used as a source of heat in a fossil fuel power plant.

• As with as a coal-fired power station about two thirds of the heat is dumped, either to a large volume of water (from the sea or large river, heating it a few degrees) or to a relatively smaller volume of water in cooling towers, using evaporative cooling (latent heat of vaporization).

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High Level Waste and Storage• With time, the concentration of fission fragments and heavy

elements formed in the same way as plutonium in a fuel bundle will increase to the point where it is no longer practical to continue to use the fuel. So after 12-24 months the “spent nuclear fuel” (SNF) is removed from the reactor. The amount of energy that is produced from a fuel bundle varies with the type of reactor and the policy of the reactor operator.

• When removed from a reactor, a fuel bundle will be emitting both radiation, principally from the fission fragments, and heat. SNF is unloaded into a storage pond immediately adjacent to the reactor to allow the radiation levels to decrease. In the ponds the water shields the radiation and absorbs the heat. SNF is held in such pools for several months to several years.

• Depending on policies in particular countries, some SNF may be transferred to central storage facilities. Ultimately, SNF must either be reprocessed or prepared for permanent disposal.

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HLW Storage Casks

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Reprocessing

• Used fuel is about 95% U-238 but it also contains about 1% U-235 that has not fissioned, about 1% plutonium and 3% fission products, which are highly radioactive, with other transuranic elements formed in the reactor. In a reprocessing facility the used fuel is separated into its three components: uranium, plutonium and waste, containing fission products.

• Reprocessing enables recycling of the uranium and plutonium into fresh fuel, and produces a significantly reduced amount of waste (compared with treating all used fuel as waste).

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THE #1 “CONCERN” REGARDING NUCLEAR ENERGY

Spent Fuel Storage

Spent Fuel

OffsiteStorage

Dry CaskStorage

Transshipping

Reracking

Existing Pools

Reprocessing (MOX)Reprocessing (MOX)

Courtesy of USEC Inc 21

FuelFabrication

($2.4 B)

Enrichment($4.5 B)

Conversion($0.5 B)

Uranium($2.2 B)

Repro – cessing($1.9 B)

• Areva/ COGEMA

• Rio Tinto Group

• Russia/ Minatom

• Cameco

• Western Mining

• Areva/ Comurhex

• BNFL

• Russia/ Minatom• Cameco

• Honeywell/ ConverDyn

• Areva/ Framatome ANP

• BNFL/ Westinghouse

• Russia/ Minatom

• AECL

• GE/Global Nuclear Fuel

• Areva/ COGEMA

• BNFL

• Russia/ Minatom

Owner/ Controlling Nation

France

U.K.

The Netherlands

Germany

Russia

Canada

U.S.

Australia

Nuclear Fuel Cycle (w/ Estimated Annual Industry Value)

and Its Primary Producers

Nuclear Fuel Cycle

Key Companies

• Areva/ COGEMA

• BNFL – 1/3 Urenco

• Dutch Govt – 1/3 Urenco

• RWE & E ON – 1/3 Urenco

• Russia/ Minatom

• USEC

Spent Fuel Storage

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Spent Nuclear Fuel Disposal & Wastes

• Presently, there are no disposal facilities (as opposed to storage facilities) in operation in which SNF, not destined for reprocessing, and the waste from reprocessing can be placed. Although technical issues related to disposal have been addressed, there is currently no pressing technical need to establish such facilities, as the total volume of such wastes is relatively small. Further, the longer it is stored the easier it is to handle, due to the progressive diminution of radioactivity. There is also a reluctance to dispose of SNF because it represents a significant energy resource which could be reprocessed at a later date to allow recycling of the uranium and plutonium. (There is a proposal to use it in Candu reactors directly as fuel.)

• Several countries are studying ways to determine the optimum approach to the disposal of spent fuel and wastes from reprocessing. General consensus favors its placement into deep geological repositories, initially recoverable.

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Spent Nuclear Fuel Disposal & Wastes (2)

• Wastes from the nuclear fuel cycle are categorized as high-, medium- or low-level wastes by the amount of radiation that they emit. These wastes come from a number of sources and include: • low-level waste produced at all stages of the fuel cycle; • intermediate-level waste produced during reactor operation

and by reprocessing; • high-level waste, which is waste containing fission products

from reprocessing, and in many countries, the used fuel itself.

• The enrichment process leads to the production of much 'depleted' uranium, in which the concentration of U-235 is significantly less than the 0.7% found in nature. Small quantities of this material, which is primarily U-238, are used in applications where high density material is required, including radiation shielding and some is used in the production of MOX fuel. While U-238 is not fissile, it is a low specific activity radioactive material and some precautions must, therefore, be taken in its storage or disposal.

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Megatons to Megawatts

A unique program that recycles uranium from dismantled Russian warheads into fuel for American nuclear power plants

• Historic 20-year nonproliferation treaty between the US and Russia

• More than 10,000 warheads have already been converted into nuclear fuel purchased by USEC

• Resulting energy is enough to power a large American city for ~300 years

• Over $3BB in payments to Russia from USEC purchases

• Signed market-based pricing agreement with Russia securing program through 2013

COST TO U.S. TAXPAYER: NOTHING

COST TO SUPPORT NONPROLIFERATION INITIATIVES: PRICELESS

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Industrial Safety

America's commercial nuclear energy industry ranks among the safest places to work in the US.

• In 2006, nuclear industrial safety accident rate= 0.12 per 200,000 worker-hours.

• U.S. Bureau of Labor statistics show that it is safer to work at a nuclear power plant than in the manufacturing sector, more than the real estate and finance industries.

• Residing adjacent to a nuclear power plant would expose a person to less radiation each year than that received in just one round-trip flight from New York to Los Angeles.

• You would have to live near a nuclear power plant for over 2,000 years to receive the equivalent dose/exposure equivalent to a single diagnostic medical x-ray.

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Background and Supporting Materials/Websites

• Nuclear Energy Institute• www.nei.org

• U.S. Dept of Energy – Energy Information Administration• www.eia.doe.gov

• U.S. Dept of Energy – Office of Nuclear Energy • www.ne.doe.gov

• U.S. Nuclear Regulatory Commission • www.nrc.gov

• www.science.howstuffworks.com/nuclear-power.htm

• World Nuclear Association • www.world-nuclear.org

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Thank you for your time

Questions?

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Operating Facts

• Currently, 103 commercial nuclear power plants are producing electricity in the U.S., located at 65 sites in 31 states.

• On average, they are 24 years old, and licensed to operate for 40 years with an option to renew an additional 20.

• Palo Verde Nuclear Generating Station in Arizona generates more electricity annually than any other U.S. power plant of any kind, including coal, oil, natural gas and hydro. The three-unit, 3,875-megawatt nuclear plant generated 24,012,231 megawatt-hours of electricity in 2006. Palo Verde generated almost as much electricity as all of the wind and solar plants in the U.S. combined in 2006.

• As of May 2007, 30 countries worldwide were operating 436 nuclear plants for electricity generation. Thirty-one new nuclear plants were under construction in 12 countries.

• In December 1951, an experimental reactor produced the first electric power from the atom, lighting four light bulbs. Nuclear energy has been used since 1953 to power U.S. navy vessels, and since 1955 to provide electricity for home use.

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Note: Taipower uses nuclear energy to generate 22% of electricity on the island of Taiwan.

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Global Warming - the science

• The greenhouse effect occurs naturally, providing a habitable climate.

• Atmospheric concentrations of some of the gases that produce the greenhouse effect are increasing due to human activity and most of the world's climate scientists believe this causes global

warming. • Over one-third of human-induced greenhouse gases come from

the burning of fossil fuel to generate electricity. Nuclear power plants do not emit these gases.

• The "greenhouse effect" is the term used to describe the retention of heat in the Earth's lower atmosphere (troposphere). In colloquial usage it often refers to the enhanced global warming which is considered likely to occur because of the increasing concentrations of certain trace gases in the atmosphere. These gases are generally known as greenhouse gases*. Concentrations of them have increased significantly during the 20th century, and a large part of this increase is attributed to human sources, i.e. it is anthropogenic.

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Responding to Global Climate Change: The Potential Contribution of Nuclear

Power

• Population and energy demand growth

• Meeting energy demand while limiting carbon dioxide emissions

• The potential role of non-fossil energy sources

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Nuclear Power:Clearly Competitive

$23.00

$35.84

$42.57

$34.64

$46.93

Nuclear BusbarCost

Mid-Atlantic

Gas-Fired Plant(fuel cost only)

California

Northeast

$ per Megawatt-hour

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Nuclear Power Costs versus Gasoline Costs

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The Facts

Economic Performance: The average electricity production cost in 2005 (per kW/hr)• nuclear energy = 1.72 cents• coal-fired plants = 2.21 cents, • oil = 8.09 cents, and • gas = 7.51 cents.

Nuclear power plants provide low-cost, predictable power at stable prices.The energy in one uranium fuel pellet—

the size of the tip of your little finger—is the equivalent of • 17,000 cubic feet of natural gas, • 1,780 pounds of coal, or • 149 gallons of oil.

Environmental ProtectionOf all energy sources, nuclear energy has perhaps the lowest impact on the environment, including water, • land, • habitat, • species and • air resources. Nuclear energy is the most eco-efficient of all energy sources because it produces

the most electricity in relation to its minimal environmental impact.

Nuclear energy is the world's largest source of emission-free energy. • Nuclear power plants produce no controlled air pollutants, such as sulfur and particulates, or greenhouse

gases.

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The Facts (2)

In 2006, U.S. nuclear power plants prevented• 3.12 million tons of sulfur dioxide, • 0.99 million tons of nitrogen oxide, and • 681.2 million metric tons of carbon dioxide from entering the earth’s atmosphere.

The NOx emissions avoided by U.S. nuclear power plants (NPP) are equivalent to

• NOx emissions from approximately 52 million passenger cars (38 percent of the U.S. total).

• CO2 emissions avoided by U.S. NPPs are equivalent to the carbon dioxide emissions from approximately 131 million passenger cars (96 percent of the U.S. total).

•  NPPs were responsible for more than a third of the total voluntary reductions in greenhouse gas emissions reported by U.S. companies in 2005 (the last year available), according to the EIA. 

Emissions reductions from nuclear energy usage amounted to • 138 million metric tons of CO2, 36 percent of the 384 million metric tons of total CO2 reductions reported. 

• Throughout the nuclear fuel cycle, the small volume of waste by-products actually created is carefully contained, packaged and safely stored. As a result, the nuclear energy industry is the only industry established since the industrial revolution that has managed and accounted for all of its waste, preventing adverse impacts to the environment.

• Water discharge from an NPP contains no harmful pollutants and meets regulatory standards for temperature designed to protect aquatic life.

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The Facts (3)

Industrial SafetyFor years, America's commercial nuclear energy industry has ranked among the safest places to work in the

US. • In 2006, nuclear's industrial safety accident rate-was 0.12 per 200,000 worker-hours. • U.S. Bureau of Labor statistics show that it is safer to work at a nuclear power plant than in the

manufacturing sector, more than the real estate and finance industries.• Residing adjacent to a nuclear power plant would expose one to less radiation each year than that

received in just one round-trip flight from New York to Los Angeles.• You would have to live near a nuclear power plant for over 2,000 years to receive the equivalent

dose/exposure equivalent to a single diagnostic medical x-ray.

Medical Diagnosis and TreatmentThe largest man-made source of radiation is medical diagnosis and treatment, including • X-rays, • nuclear medicine and • cancer treatment.

More than 28,000 American doctors practice medical specialties that use radiation.• The use of radiation for medical diagnosis and treatment is so widespread that virtually every U.S.

hospital has some form of nuclear medicine unit. • Nearly 4,000 hospital-based nuclear medicine departments across the country perform more than 10

million nuclear medicine patient procedures each year. • Molybdenum-99, is used about 40,000 times each day in the U.S. to diagnose cancer and other illnesses.• Of the 10 Nobel prizes granted in physiology and medicine from 1975 to 1989, 10 were based on

research using radioactive materials.

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The Facts (4)Food Processing and Preservation• Irradiation kills bacteria, parasites and insects in food—including

• listeria, • salmonella and • potentially deadly E. coli

• Retards non-microbial spoilage of certain foods, increasing their shelf life. • In the U.S. alone, CDC reports that more than 6.5 million serious cases of food-related illness occur each

year, causing more than 10,000 deaths.• WHO in 1992 called food irradiation a "perfectly sound food-preservation technology." The head of the

group's food safety unit said irradiation is "badly needed in a world where food-borne diseases are on the increase and where between one-quarter and one-third of the global food supply is lost post-harvest.

• The U.S. is among more than 35 countries that permit irradiation of certain foods. • Since the 1960s, NASA has included irradiated food on its space flights.• In 1963, FDA approved the irradiation of wheat, flour and potatoes

• In 1983, spices and seasonings• in 1985, pork• in 1986, fruits and vegetables• in 1990, poultry; and • in 1997, red meat.

Industrial Applications: Radiation is used to • sterilize baby powder, • bandages, • contact lens solution and • many cosmetics, including false eyelashes and mascara.

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Nuclear Energy, US NW stockpile, other NW programs, nonproliferation, and nuclear terrorism?

OR: PILING ON

• POLLINGS INDICATE THAT:• When US population combine all things nuclear, they view it as BAD

• HOWEVER, when US population views issues individually:• Nuclear energy: 67% support• Necessity for a US NW stockpile: VERY IMPORTANT• Should world be rid of NW? Yes, as long as all countries

adhere to commitment• Nonproliferation initiatives: VERY IMPORTANT• Will nuclear terrorism occur in US w/in 10y?: LIKELY

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Can the Public’s View of Nuclear Energy

be Changed?YES!!!!!

• HOW?• Education, Education, Education• Communicating with

• Public• Special interest groups• Media

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Opportunities on the HorizonFactors Driving Nuclear’s Optimistic Long-

term Forecast

• 103 operating plants continue to improve performance (plant uprates and license renewal thereby driving down cost of kWhr); maintain effective security plans

• Bush Administration’s “National Energy Strategy”

• Ever-present concerns about global warming/greenhouse gases

• Oil pricesNOT ENOUGH EDUCATION WHY NUCLEAR ENERGY IS

IMPORTANT