C H A P T E R

7

Radioactive Waste ManagementJohn E. Marra y, Ronald A. Palmer z

y Savannah River National Laboratory, Aiken, South Carolina 29802, United States of America,z Institute for Clean Energy Technology, Mississippi State University, Starkville, Mississippi 39762,

United States of America

W

O U T L I N E

1. Introduction 101

aste D

1.1. The Dawn of the Commercial NuclearPower Industry 1

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1.2. Radioactive Waste Generation 1

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101oi: 10.1016/B978-0-12-381475-3.10007-5

2. Nuclear Waste Treatment and Processing 103

3. Geologic Disposal 106

4. Conclusions 108

1. INTRODUCTION

The ore pitchblende was discovered in the1750s near Joachimstal in what is now the CzechRepublic. Used as a colorant in glazes, uraniumwas identified in 1789 as the active ingredient bychemist Martin Klaproth. In 1896, French phys-icist Henri Becquerel studied uranium mineralsas part of his investigations into the phenom-enon of fluorescence. He discovered a strangeenergy emanating from the material, which hedubbed “rayons uranique.” Unable to explainthe origins of this energy, he set the problemaside.

About 2 years later, a young Polish graduatestudent was looking for a project for herdissertation. Marie Sklodowska Curie, working

with her husband Pierre, picked up on Becquer-el’s work and, in the course of seeking outmore information on uranium, discoveredtwo new elements (polonium and radium)that exhibited the same phenomenon, butwere even more powerful. The Curies recog-nized the energy, which they now called “radio-activity,” as something very new, requiringa new interpretation, a new science. Thisdiscovery led to what some view as the “goldenage of nuclear science” (1895e1945) whencountries throughout Europe devoted largeresources to understand the properties andpotential of this material.

By World War II, the potential to harnessthis energy for a destructive device had beenrecognized and by 1939, Otto Hahn and Fritz

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Published by Elsevier Inc. All rights reserved.

7. RADIOACTIVE WASTE MANAGEMENT102

Strassman showed that fission not onlyreleased a lot of energy but that it also releasedadditional neutrons that could cause fissionin other uranium nuclei leading to a self-sustaining chain reaction and an enormousrelease of energy. This suggestion was soonconfirmed experimentally by other scientistsand the race to develop an atomic bomb wason. The rest of the development history thatlead to the bombing of Hiroshima and Naga-saki in 1945 is well chronicled. After WorldWar II, the development of more powerfulweapons systems by the United States and theSoviet Union continued to advance nuclearscience. It was this defense application thatformed the basis for the commercial nuclearpower industry.

1.1. The Dawn of the CommercialNuclear Power Industry

Both the Soviet Union and the West realizedthat the tremendous heat produced in theprocess could be tapped either for direct useor for generating electricity. It was also clearthat this new form of energy would allow devel-opment of compact long-lasting power sourcesthat could have various applications. The firstnuclear reactor to produce electricity was theExperimental Breeder Reactor (EBR-1) in Idaho,USA, December 1951. In 1953, President Eisen-hower proposed the “Atoms for Peace”program, which reoriented significant researcheffort toward electricity generation and set thecourse for civil nuclear energy development inthe United States. The main US effort was underAdmiral Hyman Rickover, which developed thePressurized Water Reactor (PWR) for naval(particularly submarine) use. The PWR usedenriched uranium oxide fuel and was moder-ated and cooled by ordinary (light) water. TheMark 1 prototype naval reactor started up inMarch 1953 in Idaho, and led to the USAtomic Energy Commission building the 60MWe Shippingport demonstration reactor in

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Pennsylvania, which started up in 1957 andoperated until 1982. The Shippingport reactorspurred the commercial nuclear power industryin the United States.

Similar development occurred across theglobe and today there aremore than 400 reactorsof varying configurations operating throughoutthe world with a total installed capacity of morethan 370 GWe or about 15% of the world’s elec-tricity (vs. coal, 40%; oil, 10%; natural gas, 15%;and hydro and other, 19%) [1]. Today, thenuclear industry is at the eye of a “perfectstorm.” Fuel oil and natural gas prices are atnear record highs, worldwide energy demandsare increasing at an alarming rate, and increasedconcerns about greenhouse gas (GHG) emis-sions have caused many to look negatively atlong-term use of fossil fuels. This convergenceof factors has led to a growing interest in therevitalization of the nuclear power industrywithin the United States and across the globe.The International Atomic Energy Agency(IAEA) upwardly revised its projections for 2030[2]. Its low projection shows an increase from372 GWe today to 511 GWe in 2030, the high onegives aprojectionof 807GWe, in linewithahigherforecast growth in power generation.

1.2. Radioactive Waste Generation

As with any industrial process, commercialnuclear power results in the generation ofprocess wastes. To facilitate communicationand information exchange regarding treatmentand handling of radioactive wastes, the IAEAinstituted a revised waste classification systemin 1994 that takes into account both qualitativeand quantitative criteria [3]. As defined below,the IAEA developed a system to classify thesewastes in three principal classes includingexempt waste (EW), low- and intermediate-level waste (LILW), and high-level waste(HLW). (Note: The quantitative cutoff pointsfor each class of waste vary from country tocountry, typically associated with radiation

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NUCLEAR WASTE TREATMENT AND PROCESSING 103

risk to the public, which depends on storageand/or disposal characteristics. The IAEA hasprovided general guidelines and these are notedbelow.)

Exempt Waste: EW contains such a lowconcentration of radionuclides that it can beexcluded from nuclear regulatory controlbecause radiological hazards are considerednegligible. As per the IAEA, the definition ofEW is based on an annual dose to members ofthe public of less than 0.01 mSv.

Low- and Intermediate-Level Waste: LILWcontains enough radioactive material that itrequires actions to ensure the protection ofworkers and the public for short or extendedperiods of time. This class includes a range ofmaterials from just above exempt levels to thosewith sufficiently high levels of radioactivity torequire use of shielding containers and insome cases periods for cooling off. LILW maybe subdivided into categories according to thehalf-lives of the radionuclides it contains, with“short-lived” being less than 30 years and“long-lived” being greater than 30 years. TheIAEA suggests limiting concentrations ofshort-lived isotopes to less than 4000 Bq g�1 inan individual waste package and concentrationsof long-lived isotopes to less than 400 Bq g�1 in awaste package.

High-Level Waste: HLW contains sufficientlyhigh levels of radioactive materials that a highdegree of isolation from the biosphere, normallyin a geologic repository, is required for longperiods of time. Such wastes normally requireboth special shielding and cooling periods. Inthe IAEA guidelines, HLW contains thermalpower above 2 kW m�3 and concentrations ex-ceeding those for LILW.

Substantial amounts of radioactive wasteare generated through civilian applications ofradionuclides in medicine, research, and ind-ustry. A typical 1000MWe nuclear power stationproduces approximately 300 m3 of LILW peryear and some 27 tonnes (27 t) of high-levelsolid packed waste per year. By comparison, a

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1000 MWe coal plant produces some 270,000tons of ash alone per year containing radioactivematerial and heavy metals which end up inlandfill sites and in the atmosphere [4]. World-wide, nuclear power generation facilities pro-duce about 200,000 m3 of LILW and 10,000 m3

of HLW (including spent fuel designated aswaste) each year.

2. NUCLEAR WASTE TREATMENTAND PROCESSING

Research studies in the management of radio-active waste began in the 1930s. As the commer-cial nuclear industry evolved through the 1960sand 1970s, additional emphasis was placed ondeveloping long-term solutions for radioactivewastes. Exempt and LILW from commercialnuclear power facilities are handled much likeordinary municipal wastes, although mostLILW is disposed of in stable near-surfacedisposal sites, or as is the case with transuranic(TRU) waste from the United States defenseprogram in stable salt-based repositories (suchas the Waste Isolation Pilot Plant, WIPP inNew Mexico, USA).

In 2007, in response to growing concerns aboutmanagement of LILWin theUnited States, theUSGovernment Accountability Office (GAO) per-formed a comprehensive review of worldwidepractices associated with LILW handling [5].This report provides a comprehensive analysisof management approaches for LILW, includingsoil, debris, rubble, process materials, andclothing that have been exposed to radioactivityor contaminated with radioactive material. Thereport also looked at disposition of excess sealedradiological sources that are no longer useful forindustrial or medical applications. The GAOfound that most countries maintain waste inven-tory databases that include information on wastegenerators (nuclear utilities, hospitals, universi-ties, and research laboratories), waste types,storage locations, and present and future waste

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FIGURE 7.1 Typical cooling basin for used nuclear fuel.

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generation predictions and disposal capacityneeds. The report also found that disposal prac-tices vary according to the hazard presented bythe LILW in question. As discussed earlier,lower-activity LILW is handled much similar tomunicipal waste and is typically disposed innear-surface burial sites that are monitored overtime. Depending on the level of activity beingtreated, most of this disposal is handled as EWper the IAEA definitions (see above) and noreview is required from the nuclear regulatoryauthority. For higher-activity LILW, most coun-tries have centralized storage and disposaloptions that are licensed by the appropriatenuclear regulatory authority. Funding for opera-tions of these facilities is either provided by thecentral government or by collecting disposalfees at the time of disposal. For sealed sourcesused in industrial and medical applications, thedisposal fee is often collected at the time ofpurchase.

The discussion in the remainder of thischapter will focus on handling of spent nuclearfuel and HLW. A typical 1000 MWe nuclearreactor generates about 23 t of used fuel eachyear. In the United States and Canada, thisused fuel is regarded as waste and is slated fordirect disposal. In most of Europe and Japan,the used fuel is reprocessed to recover unuseduranium and to efficiently manage TRU andfission products. France is widely consideredto be the world leader in commercial nuclearfuel recycling, although Russia also has severaldecades’ worth of reprocessing experience.The French program uses state-of-the-art pro-cessing facilities at La Hague in northern Franceand uses both the recovered uranium and pluto-nium to produce mixed oxide (MOX) fuel (seediscussion below). The Japanese have workedextensively with the French and are currentlyconstructing a reprocessing facility similar tothat at La Hague. Countries such as India andChina have emerging reprocessing programsassociated with the increase in nuclear powergeneration in those countries.

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In either reprocessing or direct disposal, theused fuel is first stored for several years underwater in cooling basins at the reactor site (seeFig. 7.1). The water covering the fuel assembliesprovides radiation protection, while removingthe heat generated during radioactive decay.

If the used fuel is reprocessed, the nuclearfuel assemblies are disassembled and choppedinto small pieces in a highly secure, remote pro-cessing environment. The fuel core is typicallydissolved in nitric acid and separated chemi-cally into uranium, plutonium, and HLW solu-tions. About 97% of the used fuel can berecycled leaving only 3% as HLW. The resultinghulls from the fuel assemblies are treated asLILW.

For a typical l000 MWe nuclear reactor, about230 kg of plutonium (1% of the spent fuel) isseparated in reprocessing annually. The sepa-rated Pu can be used in freshMOX fuel or storedfor later handling and disposal. MOX fuel fabri-cation has been ongoing in Europe, with some25 years of operating experience. A similar plantis scheduled to start up in Japan in 2012. AMOXfuel plant is also under construction in theUnited States (at the Savannah River Site inAiken, SC) for disposition of excess Pu fromthe United States nuclear weapons program.

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FIGURE 7.2 Approximate size of borosilicate HLW glassproduced from nuclear electricity generation over a humanlifespan.

NUCLEAR WASTE TREATMENT AND PROCESSING 105

Because of the presence of long-lived radio-nuclides, the separated HLWs (about 3% of thetypical reactor’s used fuel) need to be isolatedfrom the environment. Research into the pro-cessing and disposal of HLW has been activefor many years. Isolation of the HLW has typi-cally been in large underground storage tanks.In the United States, about 75 million gallons(284 m3) have been stored in 177 tanks at Han-ford, 53 tanks at Savannah River, and two tanksat the West Valley Demonstration Project. TheHLW is in the form of a liquid or slurry andneeds to be solidified into a waste form beforetransport to a final storage/disposal facility.

Development of appropriate waste formsbegan in the United States in the late 1940s atthe Brookhaven National Laboratory [6]. Thematerials studied were based on montmoril-lonite clay and phosphate glass. France beganmaking borosilicate glass in 1963 [7]. Over theyears, a wide variety of materials have beendeveloped and studied for the ultimate isolationand disposal of HLW. The list includes:

• Borosilicate glass• SYNROC• Porous glass matrix• Tailored ceramic• Pyrolytic carbon and SiC-coated particles• FUETAP (and other) concretes• Glass marbles in a lead matrix• Plasma spray coatings• Phosphate glass• Titanate ceramic• Various calcines

In the late 1970s, the US Department ofEnergy (DOE) formed an alternative wasteform peer review panel consisting of prominent,independent engineers and scientists withexpertise in materials science, ceramics, glass,metallurgy, and geology [8]. Using a ratingprocess to evaluate the relative merit of all thevarious proposed waste forms, the panel-selected borosilicate glass was used as the refer-ence waste form.

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Borosilicate glass is now the material ofchoice for incorporating and immobilizing thepotentially hazardous radionuclides in HLW.Factors that contribute to the suitability ofglass waste forms fall into two main categories.First, glass waste forms possess good productdurability. Various glass systems are able toincorporate a variety of waste compositionsinto durable waste forms. These forms havedemonstrated good chemical and mechanicalperformance as well as good radiation andthermal stability. Second, waste-glass formspossess good processing characteristics. Thetechnology for making waste-glass forms isboth well developed and well demonstrated.Waste-glass forms ranging in size from bench-and laboratory-scale products to multitoncanisters have been successfully produced byusing ceramic melters as well as in-can meltingtechniques. The vitrification process providesa substantial volume reduction; a piece, thesize of a hockey puck (25 mm thick, 76 mmin diameter) would contain the total HLWarising from nuclear electricity generation forone person throughout a normal lifetime (seeFig. 7.2) [9]. Vitrification has been used fornuclear waste immobilization for more than40 years across Europe, Japan, and the UnitedStates.

In a typical processing facility, the HLW solu-tion is combined with borosilicate glass-formingmaterials and sent to a Joule-heated ceramic

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7. RADIOACTIVE WASTE MANAGEMENT106

melter. Operating at w1200�C, the melter turnsthe waste slurry into molten glass that exitsthe melter into large stainless steel canisters.An international reference stainless steelcanister holds approximately 400 kg of wasteglass. After filling, the canisters are decontami-nated and sealed by welding a steel plug intothe neck of the canister. In most cases, the canis-ters are temporarily stored at the vitrificationfacility before eventual transport to a geologicalrepository.

Cement and cement-based materials areused to contain by-products from reprocessingoperations that are categorized as LILW.Common advantages of cement stabilizationinclude continuous or batch processing atambient temperatures, low-cost raw materials,suitability for large or small volumes of manydifferent waste types, and ability to usemodular equipment.

Waste stabilization/solidification is mostcommonly accomplished by mixing aqueous-based wastes with hydraulic or pozzolanicmaterials such as Portland cements, calciumaluminate cements, calcium sulfoaluminate(CSA) cements, magnesium (aluminum) phos-phate cements, kiln dusts, fly ashes, and reac-tive slags. These materials react with water toform insoluble binders. Composite cementsystems using several of these phases arecommonly used by the nuclear industry. Thehydrated binder phases encapsulate solid parti-cles in the waste, coprecipitate selected contam-inant species, and adsorb excess water andsoluble contaminants. In addition, the aqueouschemistry of the cementewaste mixture canbe adjusted so that the soluble contaminantsare precipitated from solution simultaneouslywith the formation of the matrix phases.Mixtures of the cementitious ingredients plusother additives such as sodium silicate (hard-ening agent), set accelerators, and retardersare commonly used. As a result, a monolithicwaste form can be produced at ambienttemperatures. The waste forms can also be

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designed to have a wide range of properties.Compressive strengths typically range from 50to 3000 psi (350 kPa to 20 � 103 kPa). Viscosityand set time can also be adjusted to meetmixing and placement requirements dictatedby the production process. Composite cementsare typically associated with a highly alkalienvironment that is not suitable for all wastes;Al metal for example will corrode in such anenvironment. As a result, a toolbox of cementsystems is being developed including geopoly-mers, CSA cements, and alkali-activated sys-tems with at least one suitable for all wastetypes [10].

Hydrated waste forms are typically usedfor stabilizing aqueous wastes, such as,condensed-off gas wastes, electroplatingsludges, salt solutions, incinerator ash, electro-static precipitator and bag house wastes, andprocess residues, such as, metal chloride andhydroxide bottoms from ore refining processes.Cementitiousmaterials are also used in a varietyof environmental remediation actions to stabi-lize seepage basin sludges, contaminated soils,and waste disposal sites. In addition, cement-based materials are also used for undergroundwaste tank and pipeline closures. The standardrequirement for this application is subsidenceprevention. Portland cement-based grouts orpumpable, self-leveling, self-compacting back-fills containing Portland cement are typicallyused for tank stabilization. Special groutor backfill formulations are also being designedto stabilize residual contaminants that maynot have been removed from these tanks.

3. GEOLOGIC DISPOSAL

As discussed earlier, the HLW fraction of theradioactive waste will require geological isola-tion for extended periods of time (up to1,000,000 years). When dealing with suchextended time periods, the fate of the stabilizedwaste is often questioned. In fact, there is

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GEOLOGIC DISPOSAL 107

a natural example that suggests that finaldisposal of HLW underground is safe. Over2 billion years ago (109 years) at Oklo in Gabon,West Africa, chain reactions started spontane-ously in concentrated deposits of uranium ore.Scientists estimate that these natural nuclearreactors continued operating for hundreds ofthousands of years, forming plutonium andthe other by-products created today in a nuclearpower reactor. This same area remained highlysaturated following the end of the nuclear reac-tion. Evidence shows that the materials thatwould be classified as HLW using the currentIAEA guidelines remained where they wereformed and eventually decayed into nonradio-active elements; they were not mobile in theenvironment. It is this natural analog thatprovides the basis for geological isolation ofHLW and/or spent nuclear fuel.

Worldwide, countries are working to developdeep geologic disposal facilities for a variety ofmore radioactive LILW and all forms of HLW.Although there is certainly international cooper-ation in developing programs for geologicdisposal, each country has taken a slightlydifferent approach due to differences in geolog-ical formation and their domestic nuclear poli-cies. These repository programs have beenongoing for several decades and as of thiswriting no country has fully licensed andopened a geologic repository of long-termdisposition of radioactive wastes. Sweden willlikely have the first licensed repository opensometime after 2015.

Initial discussions regarding a permanentsolution to the disposal of high-level radioactivewaste in the United States culminated in a reportby the National Academy of SciencesdNationalResearch Council in 1957 [6]. The primaryrecommendation was that “disposal in salt isthe most promising method for the near future.”Other report recommendations included stabili-zation of the waste in a “slag or ceramic materialforming a relatively insoluble product,” thepotential of disposing of the waste in a deep

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repository, the separation of Cs137 and Sr90,and consideration of the transportation costs.

A generation later, a similar report [11]expanded on the original as a result of theresearch completed in the interim. This reportconcluded that the technology for geologicdisposal “is predicted to be more than adequatefor isolating radioactive wastes.” Other recom-mendations examined the criterion for systemperformance, repository design and construc-tion, waste package design, prediction of theperformance of the system, and expanded thelist of potential host-rock candidates to basalt,granite, salt, and tuff.

Following this report, the United Statesenacted a policy to dispose of used nuclear fueland HLW from defense applications at YuccaMountain, Nevada. The US maintained thispolicy for more than 20 years and submitteda License Application for the Yucca MountainRepository to the US Nuclear RegulatoryCommission (NRC) in 2008. Recently, however,there has been a Presidential decision to cancelthe Yucca Mountain project and re-evaluatedisposal alternatives in theUnitedStates.A recentarticle [12] compared the repository programs ofthe United States and Sweden. In addition toexamining the technological aspects of geologicdisposal, this report discusses the regulatoryand bureaucratic aspects of the two programsand how those issues affect the success or failureof overall nuclear waste management systems.

The experience in the United States provesthat an essential aspect of the waste isolationstrategy is that long-term safety of geologicdisposal must be convincingly presented, andaccepted, long before a repository can beopened [13]. As discussed above, this requiressafety assessments that consider timescales farbeyond the normal horizon of societal thinking.For example, it must be acknowledged that themost robust and passively safe system that canbe devised by current generations may ulti-mately be compromised by the actions ofa future society, through inadvertent intrusion

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7. RADIOACTIVE WASTE MANAGEMENT108

[13]. These probabilities must be taken intoaccount in assessing the performance of therepository throughout its operational lifetime.Finally, the scientific analysis and decision-making process must involve stakeholders(i.e., regulators, political leaders, public interestgroups, and other non-government entities) atlocal, regional, and national levels.

4. CONCLUSIONS

Expansion of nuclear energy worldwide isnecessary to meet increased power demandsand GHG reduction targets. Virtually any inter-national energy forecast predicts large growth innuclear power generation over the next 30 to50 years. The expansion of commercial nuclearpower production will result in increased radio-active waste generation. Managing this wasteeffectively is a critical component of a world-wide “nuclear renaissance” and will continueto be a primary consideration for future nuclearfuel cycles. Past practice has proven that thewastes generated from nuclear power genera-tion can be effectively managed using technolo-gies that are well demonstrated at industrialscales, with decades of safe operating practices.As the worldwide community continues toinvestigate advanced nuclear fuel cycles, radio-active waste management considerations arebeing given increased emphasis and are, infact, being considered at the advent of proposedfuel cycles. This emphasis is necessary to ensurethat future nuclear fuel cycles remain economi-cally and environmentally competitive (ascompared with other forms of energy produc-tion) and do not produce legacy waste manage-ment issues for future generations.

References

[1] World Nuclear Association, World Energy Needs andNuclear Power. Available at: http://www.world-nuclear.org/info/inf16.html. Accessed 2009.

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[2] International Atomic Energy Agency, Energy, Elec-tricity and Nuclear Power Estimates for the Period to2030, IAEA Reference Data Series No. 1, 2009 Edition,Vienna, Austria, 2009.

[3] International Atomic Energy Agency, Classification ofRadioactive Waste: A Safety Guides, SAFETY SERIESNo. 111-G-1.1, Vienna, Austria, 1994.

[4] Alex Gabbard, Coal Production: Nuclear Resource orDanger, ORNL Review, Volume 26, 3/4, Oak RidgeNational Laboratory, Oak Ridge, Tennessee USA, 1993.

[5] United States Government Accountability Office,Low-Level Radioactive Waste Management:Approaches Used by Foreign Countries May ProvideUseful Lessons for Managing U.S. Radioactive Waste,GAO-07e221, US Government Accountability Office,Washington, DC, USA, 2007.

[6] United States National Academy of Sciences e

National Research Council, The Disposal of Radioac-tive Waste on Land, Report of the NRC Committee onWaste Disposal of the Division of Earth Sciences,September 1957.

[7] Yves Sousselier, Use of Glasses and Ceramics in theFrench Waste Management Program, in Ceramics inNuclear Waste Management, CONF-7990420, T.D.Chikalla and J.E. Mendel, editors, 1979, p. 9.

[8] L.L. Hench, The 70’s: From Selection of AlternativeWaste Forms to Evaluation Storage System Variables,in Environmental Issues and Waste ManagementTechnologies in the Ceramic and Nuclear Industries,Ceramic Transactions, Volume 61, V. Jain andR. Palmer, editors, 1995, p. 129.

[9] World Nuclear Association, Waste Management. Avail-able at: http://www.world-nuclear.org/education/wast.htm. Accessed 2007.

[10] N.B. Milestone, Reactions in Cement EncapsulatedNuclear Wastes: Need for a Toolbox of DifferentCement Types Adv. Appl. Ceramics 105(1), 2006,13e20.

[11] T.H. Pigford, The National Research Council Studyof the Isolation System for Geologic Disposal ofRadioactive Wastes, in: Peter L. Hofmann (Ed.), TheTechnology of High-Level Nuclear Waste Disposal,1987.

[12] L.G. Eriksson, Spent Fuel DisposaldSuccessvs. Failure, Radwaste Solutions, January/February,2010, 22.

[13] Organization for Economic Cooperation and Devel-opment, Nuclear Energy Association, The Environ-mental and Ethical Basis of Geological Disposal ofLong-Lived Radioactive Wastes: The GeologicalDisposal Strategy for Radioactive Wastes, OECDPublications, 2, rue Andre-Pascal, 75775 Paris Cedex16, France, 1995.

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