Questions

1. What is the difference between a terrorist and a guerilla fighter?

2. What is a dirty bomb?

3. What is the radiological danger of the dirty bomb?

The fuel cycle requires a number of mechanical milling, chemical conversion,and nuclear enrichment processes that require an industrial complex describedas nuclear fuel cycle. The fuel cycle produces substantial amounts of nuclearradioactive waste which needs to be reprocessed or stored for a long time.

The Nuclear Weapons Fuel Cycle

Mining Uranium OreUranium is a naturally occurring element that is more abundant in granites (~3.5 ppm) than in basalts (~1 ppm). The large size of the uranium atom prevents it from easily entering the structures of common rock‐forming minerals, so it is an element that tends to remain in magmas until a late stage of crystallization, when it forms minerals, or oxidizes to uranium oxide, uraninite (UO2). Uranium minerals dissolve in hot water and is dispersed by hydrothermal processes, causing  uranium deposition. There are about 200 known uranium minerals, but only a few are being mined commercially.

World‐Wide Uranium Mining

Closed and Operating Uranium Mines

in 2004

Mining PracticeThe depth of uranium mineralization and deposition by hydrothermalcycles decides between open‐pit mining and deep underground mining.Open‐pit mining has the advantage of higher productivity, higherrecovery, safer working conditions, and lower costs. The disadvantage isthe ecological impact and the costs associated with the mine closure.

Production from open pit mining (27%), underground mining (40%), in situleaching (21%), and byproducts (12%). Both open pit mining produce wastes,which are comprised of overburden (soil and rock covering the ore deposit,containing trace amounts of the ore and radioactive decay products).

Mine rehabilitation

Ecarpiere Uranium Mine in France, operated between 1957 and 1995

The U.S. Environmental Protection Agency EPA is currentlyembroiled in a massive effort to assess 520 open abandoneduranium mines all over the Navajo reservation. It is claimedthat there are about 1300 abandoned uranium mines onNavajo land alone.

For uranium deposits at a depth of more than 200 m underground mining becomes thefinancially more advantageous method. It involves the use of heavy mining equipment.

Underground Uranium Mining

Milling the OreThe ore material is crushed mechanically and grounded to suitable site. Toastingof the ore is necessary to destroy organic carbon material which could interferewith the purification process. The ground ore is leached with sulphuric acid orsodium carbonate to generate a more solvable uranium component (leaching).

Liquid‐solid separation by diffusion,centrifuge techniques, or drainagetechniques is followed by chemicalpurification process to produceuranium tri‐oxide (yellow cake) asfinal product of the milling process.

Leaching of Mill tailings Considerable amounts of heavy metals and long term radioactivity may bereleased and distributed through aqueous or acidic solution processes frommine waste material (mill tailing).

In‐situ leaching by H2SO4 orNa2CO3 chemistry is an oftenapplied technique to resolveuranium in the mining process.

Tailings pond of a uranium processing plant

Natural Uranium Isotope Distribution 

Uranium comes in two long‐livedisotope components 235U and 238U,with the abundance ratios dependingon the physical and chemicalfractionation processes associatedwith the uranium deposition andmineralization process.

The example shows that uranium insea‐water contains more 235U thanuranium containing minerals. (exceptfor marine carbonate samples whichare correlated with the sea waterabundance ratio through chemicalexchange processes.

Uranium Enrichment RequirementsThe use of uranium in fission reactors or in fission weapon devices requires an enrichment of 235U from the natural ~0.72% to higher values suitable for the respective application.

Modern light water reactors require an 235U enrichment of 3%. Reactors for ship propulsion require 10% enrichment to reduce the 

reactor dimensions. Nuclear submarine fuel requires 90% (weapon grade) enrichment 

because of reactor size limitations Fission weapons require 90% enrichment to maximize neutron flux 

and explosive power.

Boundary between low enrichment and high enrichment is set at 20%

NS Savannah 1962 USS Nautilus 1954Light water reactor Modern warhead

Uranium Conversion ProcessThe three primary enrichment processes are electromagnetic separation,gaseous diffusion, and centrifugation. All of these methods rely on volatileuranium compounds, primarily uranium hexafluoride UF6 which must beproduced chemically from yellow cake.

Milled uranium ore—U3O8 or "yellowcake"—is dissolved in nitric acidHNO3, yielding a solution of uranyl nitrate UO2(NO3)2. Pure uranyl nitrateis obtained by solvent extraction, then treated with ammonia to produceammonium diuranate (NH4)2U2O7. Reduction with hydrogen gives UO2,which is converted with hydrofluoric acid (HF) to uranium tetrafluoride,UF4. Oxidation with fluorine yields UF6.

During nuclear reprocessing, uranium is reacted with chlorine trifluorideto give UF6: U + 2 ClF3 →UF6 + Cl2

Chemical Conversion and Storage

Conversion FacilitiesCountry Owner/Controller Plant Name/Location Capacity 

[MTU/year]Brazil IPEN  São Paulo 90

Canada Cameco Port Hope, Ontario  10,500

China CNNC  Lanzhou 3000

France

COMURHEX (100% Areva NC ) Pierrelatte 14,000

Areva NC  Pierrelatte TU5 350

Iran AEOI  Isfahan 193

Russia RosatomEkaterinburg 4,000Angarsk 20,000

United Kingdom Springfields Fuels Ltd. (Westinghouse)

Springfields, Lancashire  6,000

United StatesConverdyn (50% Honeywell International , 50% General Atomics)

Metropolis, Illinois 17,600

Total 75,733

Electromagnetic separationCalutron, originally designed by Ernest Lawrence and operated on ORNL Y‐12 plant

Calutrons use substantial amounts of electrical power. It is estimated that calutrons built in Iraq by the Baath regime of Sadam Hussein after the Israeli bombing of the Osirakreactor required about 140MW of power for operating 90 calutrons.

Gaseous diffusionUF6 is sufficiently volatile to be used in the gaseous diffusion process. UF6, a solidat room temperature, sublimes at 56.5 °C (133 °F) at 1 atmosphere. The triplepoint is at 64.05 °C and 1.5 bar. Applying Graham's Law to uranium hexafluoride:

where:

Rate1 is the rate of effusion of 235UF6.Rate2 is the rate of effusion of 238UF6.M1 is the molar mass of 235UF6M1= 235.043930+6×18.998403 =349.034348 g∙mol−1M2 is the molar mass of 238UF6M2= 238.050788+6×18.998403 =352.041206 g∙mol−1

Diffusion Cascade

K‐25 diffusion plant

A cascade is a sequence ofdiffusion stages with theenriched 235U from onestage being fed into the nextstage, gradually improvingenrichment level.

Gaseous Diffusion PlantsCountry Owner/Controller Plant Name/Location Capacity [1000 

SWU/year]

Argentina CNEA  Pilcaniyeu 20China CNNC  Lanzhou 900?France EURODIF Tricastin 10,800

United States U.S. Enrichment Corp. 

Paducah, Kentucky  11,300Portsmouth, Ohio (closed since May 2001)

(7,400)

Subtotal 23,020

SWU stands for Separative Work Units or the amount of separation done byan enrichment process—is a function of the concentrations of the feedstock,the enriched output, and the depleted tailings. SWU is expressed in unitswhich are calculated to be proportional to the total input (energy / machineoperation time) and to the mass processed.

Gas Centrifuge

Separation of uranium isotopesrequires a centrifuge that can spinat 1,500 revolutions per second.

Zippe Centrifuge The centrifuge was developed in the Soviet Union by a team of 60Austrian and German scientists captured after World War II, workingin detention. The centrifuge is named after the team's experimentalleader Gernot Zippe (1917‐2008).

After the scientists were releasedfrom Soviet captivity in 1956, GernotZippe was able to reproduce hisdesign at the in the United States.Dr. Zippe left the United States whenhe was effectively barred fromcontinuing his research unless hewould become citizen. He refused,returned to Europe where he and hiscolleagues improved the centrifugeby changing the material of the rotorfrom aluminum to a stronger alloy,which allowed higher speed. Thisimproved centrifuge design is usedby the commercial company Urencoto produce enriched uranium fuel .

In 2004 Abdul Qadeer Khan, a Pakistani engineerat Urenco smuggled plans and critical parts ofthe centrifuge from the Netherlands to Pakistan,providing the basis for the Pakistani enrichmentand nuclear weapon program.

Centrifuge PlantsCountry Owner/Controller Plant Name/Location Capacity a) [1000 SWU/year]Brazil INB  Resende ?

China CNNC Hanzhong 500Lanzhou 500

France Eurodif Georges Besse II, Tricastin (under constr.)Germany Urenco Deutschland GmbH Gronau 4,200India DAE Nuclear Fuel Comple Ratnahalli, Karnataka 4.5

Iran AEOI Natanz ?Qom ?

JapanJNC  Ningyo Toge 200Japan Nuclear Fuel Ltd (JNFL)  Rokkasho‐mura 1,050

Korea, DPRYongbyon 8Tongchang ?

Netherlands Urenco Nederland BV Almelo 5,000

Pakistan Pakistan Atomic Energy Commission (PAEC)  Kahuta 5

Russia Rosatom

Urals Electrochemical Integrated Enterprise 7,000

Siberian Chemical Combine (SKhK), Seversk 4,000

Electrochemical Plant (ECP), Zelenogorsk 3,000

Angarsk Electrolytic Chemical Combine 2,600United Kingdom Urenco UK Ltd. Capenhurst 5,050

USA Urenco USA National Enrichment Facility , Lea County, NM (under constr.)

Subtotal 33,117.5

Enrichment Plants 1980 

Separation Work Units

1980:  49,700 kSWU/yToday: 56,195 kSWU/y

Separation capability increased since 1980.

Nuclear Waste DisposalDecades of production of plutonium and enriched uranium for nuclear weapons leftimmense legacies of contamination and toxic wastes in the United States. This createdsignificant cleanup challenges at more than 100 locations, some covering hundreds of squaremiles.

This legacy includes 75 million cubic meters of contaminated soil and 1.8 billion cubic metersof contaminated groundwater.

Toxic materials and wastes deposited in the environment by nuclear materials productioninclude radioisotopes, large amounts of organic compounds like carbon tetrachloride andmetals such as lead, cadmium, chromium, beryllium and mercury.

The Department of Energy, which inherited the nuclear weapons production complex, muststore, treat and dispose of more than 160,000 cubic meters of solid radioactive andhazardous waste and more than 100 million gallons of liquid, high‐level radioactive waste.Add to these more than 2,300 metric tons of spent nuclear fuel and at least 38 tons ofseparated plutonium 239 declared a surplus to the weapons stockpile.

In 2000, the Energy Department estimated that cleaning up the nuclear weapons productioncomplex would cost $212 billion and take 70 years. Even so, long‐term monitoring andmaintenance of contaminants left in place would be needed at 109 sites across the country.

Waste Isolation Pilot Plant WIPP

WIPP underground storage

Long term storage in salt mine environment with permanent enclosure within 70 years!

Future uncertain, Yucca Mountain?

1. Canisters of waste, sealed in special casks, are shipped to the site by truck or train. 2. Shipping casks are removed, and the inner tube with the waste is placed in a steel, 

multilayered storage container. 3. An automated system sends storage containers underground to the tunnels. 4. Containers are stored along the tunnels, on their side.  

Long term storage site for industrial waste and high level military nuclear waste 

Storage and Distribution SystemFor 30 years pursued by DOE and developed by LLNL engineering 

America without a site?DOE officials filed a motion on March 2010 with the Nuclear Regulatory Commission to withdraw the agency's license application for the Yucca Mountain site. The DOE request to withdraw the license application was turned down by the Atomic Safety and Licensing Board (ASLB) on June 29, 2010. Special Commission looks for solution!

How big is the US high‐level radioactive waste problem?

More than 75,000 metric tons of spent nuclear fuel arestacked up at 122 temporary sites in 39 states. America’s104 commercial nuclear reactors produce about 2,000metric tons of spent nuclear fuel each year. If all reactorswere to be relicensed for 60 years, they would produceabout 130,000 metric tons of spent nuclear fuel over thattime, the DOE reported in 2008.

Alternatives are:1. Reprocessing spent uranium reactor fuel.2. Fast neutron reactors.3. Accelerator Driven Systems ADS.4. Deep geological disposal.