SPECIAL REPORT

Radioactive waste disposal:Global experience and challenges

With extensive experience in disposal of low- and intermediate-levelradioactive wastes, countries are addressing some new challenges

Since the world's first disposal of radioactivewaste in Oak Ridge, Tennessee, in 1944, con-siderable experience has been acquired in thefield. The first disposal site — intended for"actively contaminated broken glassware ormaterials not sufficiently clean to be used inother work" — was a simple trench filled withunconditioned waste located on the Oak Ridgesite. Similar approaches were adopted by othernuclear facilities and waste generators in theUnited States and other countries during theearly phases of nuclear power's development.

Today, the world's disposal sites for low-and intermediate-level radioactive wastes(LILW) range from near-surface facilities toengineered geological repositories. More thanone hundred LILW disposal facilities are, orhave been, operating, and more than 42 reposi-tories are under some stage of development inthe IAEA's Member States. (See the table onpages 38 and 39.)

Accompanying the progress, a number ofissues and challenges have arisen in countriespursuing radioactive waste disposal options. Atthe global level, the IAEA has been working toassist them in these efforts by promoting thetransfer of technologies, particularly to develop-ing countries. The work entails the collection,summary, and dissemination of updated techni-cal information and support for co-ordinatedresearch programmes on specific technicalaspects. Within that context, this article presentsan overview of international experience in land-based LILW disposal systems, and addressesthe emerging issues and challenges now facingcountries in this field.

Mr. Bonne is Head of the IAEA's Waste TechnologySection of the Division of Nuclear Power and the FuelCycle, and Mr. Heinonen and Mr. Han are staff members inthe Division.

Practices and trends

Site selection. Siting a radioactive wastedisposal facility refers to the process of select-ing a suitable location that must take intoaccount technical and other considerations.Technical factors cover a long list: geology,hydrogeology, geochemistry, tectonics and seis-micity, surface processes, meteorology, human-induced events, transportation of waste, landuse, population distribution, and environmentalprotection. Another key factor today is publicacceptance, particularly in industrialized coun-tries where a locality's "not-in-my-backyard"attitude can hinder the siting of all types ofindustrial waste facilities, not just radioactivewaste sites. This has caused planners to focusgreater attention on societal factors duringearly phases of the siting process. In somecases, repositories are being co-located at siteswhere nuclear facilities already exist; for exam-ple, Drigg (UK), Centre de la Manche (France),Rokkasho (Japan), and Olkiluoto (Finland).Some countries also have talked about the con-cept of siting a regional-multinational reposito-ry (discussed in more detail later). However,political factors and public concerns have keptany regional repositories from being developedin the world.

Currently in countries around the world, atleast 17 sites have been selected for new LILWrepositories, some of which already arelicensed or under construction, while morethan 25 sites are being investigated in 17 coun-tries. They include China, which is planning todevelop four LILW repositories, and hasselected two sites for its northwest and south-ern regions. The northwest disposal site islocated in an arid and sparsely populated areaof the Gobi Desert. In the United States, no

by Kyong WonHan, JormaHeinonen, andArnold Bonne

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SPECIAL REPORT

new commercial repository for low-levelwastes has been constructed since the passageof the Low Level Radioactive Waste Policy Actof 1980. In eight US states, the site selectionprocess is in some stage of progress. Four sitesalready have been selected by Nebraska(Central Interstate Compact), North Carolina(Southeast Compact), California (SouthwestCompact) and Texas (pending the TexasCompact), and are now in the licensing process.

In addressing public acceptance issues,countries are taking several kinds of steps. InAustralia, a comprehensive public consultationprocess characterizes the process of selectingthe site of an engineered LILW repository. InCanada, where community opposition delayedthe siting of a disposal facility for waste fromradium and uranium refining activities, theGovernment halted the first site selectionprocess and established a co-operative five-phase programme implemented by an indepen-dent siting task force. The task force worksclosely with municipal councils of the partici-pating communities and with community liai-son groups set up as information conduits withthe general public. In Hungary, after two sitingattempts stalled, a national siting project forLILW. disposal was initiated by the HungarianAtomic Energy Commission in 1992. Followinga volunteer approach, the AEC found communi-ties that volunteered to host sites, and in thosethat did, six sites have been selected. The com-munities now will be involved in detailed siteinvestigations. In the United States, similarapproaches also have been initiated. Forinstance, in Connecticut, where public resis-tance initially was met, the process was adapt-ed to allow for greater public involvement ontwo aspects — "choice and control" — thatmay significantly influence the way the sitingprocess is perceived and received.

Design factors. The type of repositoriesultimately selected depend upon each coun-try's geological conditions, specific disposalrequirements, and regulatory approaches. Allof these factors are tied to the facility's design.In general, the design aims to limit the releaseof contaminants or radionuclides to the bios-phere; minimize exposure of workers and thepublic; and minimize maintenance during thepost-closure phase. The aims can be achievedthrough technical components such as thewaste package, engineered structures, the siteitself, or a combination of these.

Some noticeable trends in design are relat-ed to technological advances in the field of

waste disposal and public concerns over safe-ty. One general tendency is that more relianceis being placed on a system of multiple engi-neered barriers to contain the waste. Such asystem includes concrete vaults, backfillingmaterials, chemical barriers, and measures forgas venting, drainage, and buffer zones.

Worldwide, several different types ofLILW facilities have been designed. About62% of LILW repositories are engineerednear-surface facilities within about 10 metersof the earth's surface, 18% are more simplifednear-surface facilities, 7% are mined cavities,and 4% are geological repositories. The typeof facility ultimately selected and designeddepends on the characteristics of the wasteitself, as well as the site, and on national strate-gies and social and economic factors.Following are brief overviews of the differentdesigns:

Simple near-surface facilities. Examplesof these types of facilities include Barnwell(USA), and Vaalputs (South Africa), both ofwhich benefit from the low permeable claylayer and/or low precipitation rate at the site.At Barnwell, the disposal system consists oftrenches with a slightly sloped floor coveredwith a layer of sand to facilitate collection ofinfiltrating water in a trench drain. The trenchdrain ends in a sump which is monitored.Waste, packaged in boxes, drums and casks, isstacked in the trenches. Higher activity wastesare conditioned with concrete, bitumen, orother low leachability materials or placed inhigh integrity containers for structural stabili-ty. The space between the waste containers isfilled with dry soil, and the trench is then cov-ered with clay and soil. In Vaalputs, long andwide trenches, nearly eight meters deep, arecovered by several layers of compacted clayand indigenous sand and vegetation.

Engineered near-surface disposal facilities.Examples here include the Drigg (UK) facility,where a simple trench concept was phased out infavour of engineered vaults. It is designed toaccept LLW waste packages in containers ofhighly compacted waste in steel overpacks thatforklifts then place into concrete vaults. Thevaults, set on or below ground level, consist of aconcrete base and walls with an underlyingdrainage layer. Any drainage from within orbelow the vault can be independently monitoredand routed to an on-site water management sys-tem before discharge via a marine pipeline.

Concrete vaults in a box design are beingused at sites including the Centre de la Manche

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and l'Aube (France), El Cabril (Spain),Trombay (India), and Rokkasho (Japan). Eachone has unique design features. At la Manche,drums containing more active short-lived LILWare built into concrete walled monoliths at thebase, with drums of lower activity stacked ontop and then covered. The second French repos-itory, l'Aube, takes advantage of the experience.There, all waste is isolated within reinforcedconcrete vaults (30 meters wide, 30 meterslong, 8.5 meters high, with 30-centimeter thickwalls). Vaults are built above the highest level ofthe groundwater table, and have additionaldesign features to guard against rainwater infil-tration. Also developed was a waste packagehandling system that workers operate remotely,which reduces their exposure to radiation.Based on earlier experience, a highly automatedrecord management system was created.

In Spain, El Cabril follows a similar dis-posal concept, and incorporates the potentialretrievability of waste packages; it also haswaste conditioning and characterization facili-ties. In India, where six LILW repositories areoperating, the design features reinforced con-crete trenches and tile holes for different typesof waste. At Trombay, the reinforced concretetrenches are waterproofed and covered withreinforced concrete; additional water repel-lants are used to prevent any ingress of mon-soon water. Circular tile holes some fourmeters deep are designed to accommodatewaste with activity higher than permissible forreinforced concrete trenches and forstorage/disposal of alpha contaminated waste.

In countries of the former Soviet Union,LILW disposal facilities typically were built inthe 1960s and 1970s and have been used forwaste containing various radionuclides.Similar types of repositories were built inEastern European countries. The standarddesign called for them to be located at leastfour meters above the water table. At theSergiev Posad repository (Russia), concretevaults were built just below ground surface.They are made of double-layered concretewalls containing bitumen layers. Waste pack-ages are placed in individual compartmentsthat are filled in with mortar made of cementand low-level liquid waste. When a compart-ment is full, the waste is covered by a concretelayer as well as a re-enforced concrete plate,two layers of bitumen, and a clay soil cap.

In Japan, at Rokkasho-mura, concrete pitsare used between which a drainage system isinstalled as an engineered barrier in view of the

fact that the repository is located under thegroundwater table. One pit can accommodateapproximately 5000 drums. Once full, the dis-posal pits will be backfilled and covered with atleast four meters of soil.

In Canada, waste disposal engineers havedesigned what is called the "intrusion resistantunderground structure", or IRUS. Its featuresinclude a concrete module with a thick con-crete cap and permeable bottom that will bebuilt above the water table in a sand formation.The permeable floor is designed to minimizethe contact of water with the waste. Since thewaste will contain small concentrations of verylong-lived radionuclides, engineers haveplanned for the eventual infiltration of water asthe concrete deteriorates over the long term:any water is channeled to readily drain throughthe floor, which is formed of two mixed layersof sand, clay, and natural zeolite. The adsorp-tive properties of the layers will limit therelease of radionuclides with the drainingwater.

Mined cavities. This concept is followed inthe Czech Republic, Sweden, Finland, andNorway, for example. In the Czech Republic,part of Richard II mine cavern, 70 to 80meters underground, is used as a repository forinstitutional radioactive waste (mostly short-lived). Currently, the mine is dry and its geo-logical environment is marly limestone andmarlstone. In Sweden, the Swedish FinalRepository (SFR) is built in crystalline rockabout 60 meters under the sea bottom withaccess from land. The layout of the rock cham-bers have been adapted to the different types ofshort-lived LILW, their radioactivity content,composition, and handling requirements. Silo-shaped caverns 50 meters high with concretewalls, a bentonite clay buffer, and gas ventingsystem house the waste packages containingthe highest levels of activity. In Finland,Olkiluoto is similar to the SFR but it has onlytwo silos — one for low-level wastes and theother for heatgenerating intermediate-levelwastes — constructed 60 to 100 meters under-ground. Crushed and ground host rock is usedas backfill, and major water-bearing fracturezones will be sealed with concrete plugs.

Geological repositories. The Morsleben andKonrad (Germany) sites, as well as the plannedNIREX repository (UK), are examples of geo-logical repositories for LILW. Morsleben islocated in a very dry and stable salt mine rough-ly 500 meters underground, and has a capacityof 40,000 cubic meters of waste. ILW are dis-

IAEA BULLETIN, 39/1/1997 35

SPECIAL REPORT

posed of in a large cavity which is then back-filled in layers for shielding; LLW is stacked inexcavated chambers. The Konrad site is anexceptionally dry former iron mine which iseasy to mine, stable, confined by other layers,and covered by about 400 meters of thick clay.According to the safety assessment, the time forwater to travel from the repository to the surfacewould be 380,000 years. Horizontal repositorytunnels are to be built at a depth of about 800meters for disposal of non-heat generatingwastes, while two shafts and tunnels will beused for transportation.

. Licensing. Because of different legal andregulatory structures and requirements, thelicensing process differs among countries.For instance, in Germany a single licensingprocess covers construction, operation, andclosure of a repository, whereas severallicensing steps are required in other coun-tries. In general, the license application isbased on site-specific repository design andsafety assessments which must demonstratecompliance of the proposed facility with reg-ulatory requirements. Licensing typicallyinvolves complex legal and political proce-dures, intensive technical reviews by the reg-ulatory body, and interaction with the public.

In Switzerland, the site of Wellenberg inCanton Nidwalden was announced in June1993 as a suitable potential site for LILW dis-posal after extended investigations. TheSwiss licensing procedure includes federal,cantonal, and community licenses for theconstruction and later for the operation of therepository. In addition, a special mining con-cession must be granted by the Canton. Thegeneral license was submitted to the SwissFederal Government in June 1994, whosedecision is subject to ratification by theFederal Parliament. In the meantime, the sit-ing community of Wolfensehiessen and thecommunity assembly voted in favour of theproject in 1994. However, the cantonal vote inJune 1995 regarding the mining concessionwas slightly negative.

In Germany, the Konrad mine in LowerSaxony was investigated from 1976 to 1982 todetermine its suitability as a radioactive wasterepository. When the investigations were com-pleted, application was made for a license tobegin repository construction. While all hur-dles have been passed at the federal level, theregional government has not rendered its deci-sion on the license application. In the UnitedStates, four states (California, Nebraska,

North Carolina, Texas) submitted licenseapplications in late 1989, July 1990,December 1993, and March 1992, respective-ly. Up to now only California has obtained alicense, issued by the California Departmentof Health Services (DHS) on 16 September1993. However, the license was conditionedon DHS ownership of the land. On 1 June1994, the Superior Court of the State ofCalifornia ordered DHS to reconsider itsapproval of the license. DHS is appealing thecourt's order. In Nebraska, US Ecology,which has responsibility for siting, submittedthe eighth and final revision of the SafetyAnalysis Report plus various other docu-ments relating to the license application on 15June 1995. In North Carolina, due to politicalreasons, the application will not be approvedbefore February 2000 by the state's Divisionof Radiation Protection in the Department ofEnvironment, Health and Natural Resources.

Closure. Once a disposal facility is full, ordisposal operations are stopped for other rea-sons, the process known as "closure" and"post-closure" begins. The closure processinclude steps to secure the facility, such ascovering or sealing the disposal areas, compil-ing documents,, and performing safety assess-ments. In many countries, several hundreds ofyears are foreseen for post-closure institution-al control. This may include access control,maintenance, site monitoring, recordkeepingand corrective actions, if required.

In France, the Centre de la Manchereceived its last waste package in June 1994and steps now are being taken in preparationfor closure. The facility operator, the FrenchNational Radioactive Waste ManagementAgency (ANDRA), has applied for a licenseconcerning the institutional control phase.Once the licence is granted, the site will con-tinue to be under ANDRA responsibility. Thelicense is expected to be granted in 1997, fol-lowing a second public hearing that will pro-vide guidance on institutional control activitiesincluding active and passive surveillance.

Emerging issues and challenges

A number of issues have emerged that aredrawing close attention at the national andglobal levels. They include those concerning:

Naturally occurring radioactive materi-als (NORM). The earth's environmentincludes naturally occurring radionuclides,

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SPECIAL REPORT

including potassium-40 and carbon-14, andradioactive heavy elements originating fromthe uranium and thorium decay series. Theycan be contained in residues, or wastes, result-ing from any activities that involve removingnatural materials from the earth or processingthose materials (e.g. mining or oil and gas pro-duction). Also coal combustion results in con-centration of radionuclides in the ash as well assignificant airborne release of radioactivity. Theradiological hazard due to NORM in wasteproducts is mainly from radium and its progeny.Associated radiation doses may not be insignif-icant and indeed will often be higher than radi-ological standards set for the control of radia-tion from practices involving the use and appli-cation of radioactive materials.

The concerns have prompted regulators toconsider the potential hazards associated withdisposal of NORM wastes. In some countries,some of these wastes are now managed likeradioactive waste although the level of controlvaries widely. A recent survey has shown thatradionuclide concentrations in oil/gas pro-cessing pipelines can approach levels abovewhich it would be deemed unacceptable fornear-surface disposal of radioactive waste. Insome countries, some byproducts of oil/gasproduction and processing are already man-aged as low-level radioactive waste, while inother countries it remains uncontrolled.

Very low-level waste (VLLW). This typeof waste sometimes is generated in large vol-umes but carries low potential hazards. It cre-ates a problem because it is neither practicalto dispose of it in LILW repositories noracceptable to dispose of it as industrial waste.Presently, there is no internationally agreeddefinition of VLLW, and the issue's resolutiondepends upon the development of regulatorycriteria, among other factors.

In Sweden, several earthen mound facili-ties are in operation at each nuclear powerplant site to dispose of VLLW. Such disposalcan only be exercised for the waste requiringless than 100 years of radiological control. InFrance a large portion of VLLW is sent to theL'Aube repository while the remaining por-tion is kept at the sites. All told, French indus-try officials estimate the total amount ofVLLW to be about 15 million metric tons, andefforts have intensified to find a more satis-factory solution to its disposal. A recentstudy by an industrial working group consid-ered four types of disposal facilities forVLLW, three in tumulus structures and one

underground. These designs are under reviewby the licensing authority. In Japan, the JapanAtomic Energy Research Institute (JAERI)has launched a programme to demonstrate thesafety of near-surface disposal for VLLW. Thetype of waste for disposal in the demonstra-tion project is mainly concrete chunks of reac-tor shields and contaminated structures fromthe country's Demonstration Power Reactorcontaining radionuclides several orders lowerthan the legal limits. Having obtainedapproval for building the test facility, a pit hasbeen excavated at the reactor site, whichaccommodated 1700 tons of the waste fromNovember 1995 to March 1996. The disposalpit has been covered by a thick landfill withgrass on top and the site will be controlled forabout 30 years.

Spent sealed radiation sources (SRS).More than half a million sealed radiationsources are widely used in medicine, research,agriculture, and other fields. Once used, orspent, they require careful management beforetheir safe disposal. Experience has beenacquired for all steps in the management ofspent SRS, except for the disposal of long-lived sources. However, not all countries havethe resources to implement existing methods.

Provided a near-surface facility is properlysited, constructed and operated, it may safelybe used for the disposal of most spent SRS,with the exception of americium-241 and radi-um-226 and the large sources used in telether-apy or radiation facilities. The acceptabilityof waste at a given repository is subject to cri-teria which include a concentration limit forthe different radionuclides or groups ofradionuclides in a waste package and the totalactivity.

Many countries generate only smallamounts of radioactive waste including spentSRS, up to a few cubic meters per year. Thesecountries could benefit from establishingregional-multinational repositories. Othercountries with operational repositories arefacing different types of concerns with spentSRS. For example, in Russia, long-lived spentSRS (e.g. radium sources) are stored forfuture geological disposal and others are dis-posed of in concrete vaults or in boreholesbuilt in shallow ground. The borehole con-cept, developed from the end of 1950s to thebeginning of 1960s by the former USSR,involves dropping spent SRS through a spiralloading channel into a five meter deep stain-less vessel situated in a concrete-lined bore-

IAEA BULLETIN, 39/1/1997 37

SPECIAL REPORT

Status of low and intermediate level waste disposal facilities in various countries in 1996

Country Repository(date opened/closed)

In the process of site selectionAustraliaBelgiumBrazilBulgariaCanada (historic LLW)China (East)

(Southwest)CroatiaCubaEcuadorHungaryIndonesiaKorea, Republic ofPakistanSloveniaTurkeyUnited KingdomUnited States (Connecticut)

(Illinois)(Massachusetts)(Ohio)(Michigan)(New Jersey)(New York State)(Pensylvania)

Site selectedChinaCyprusEgyptMexicoPeruRomaniaSwizerland

Under licensingCanadaGermanyNorwaySlovak RepublicUnited States

Under constructionChinaFinland

In operationArgentinaAzerbaijanAustralia

Belarus'BrazilCzech Republic

FinlandFranceGermanyGeorgia

Guangdong Day a BayAri FarmInshasLaguna VerdeRASCOCernavodaWellenberg

Chalk RiverKonradHimdalenMohovceWard Valley, CaliforniaBoyd County, NebraskaWake County, North CarolinaFackin Ranch, Texas

Gobi, GansaLoviisa

Ezeiza(1970-)Baku (1960s-)Mt. Walton East (1992-)

Ekores, Minsk reg.(1964-)AbadiadeGoias(1996-)Richard 11(1964-)Bratrstvi (1974-)Dukovany (1994- )OIkiluoro ;M)f>2 ;Centre del'Aube (1992-)Morsleben(1981-)Tabilisi (1960s-)

RepositoryConcept

ENSFENSFENSFENSF----MCENSF

ENSF

ENSFGR-ENSF-ENSFENSF_ENSFENSF

ENSFSNSFENSFENSFENSFENSFMC

ENSFGRMCENSFENSFENSFENSFENSF

ENSFMC

ENSFENSFENSF

ENSFENSFMCMCENSFMCENSFGRENSF

Country

HungaryIndia

IranIsraelJapan

Kazakstan

KyrgyzstanLatviaMexicoMoldovaPakistan

PolandRomaniaRussia2

South Africa

SpainSweden

United Kingdom

Ukraine

United States

Repository(date opened/closed)

RHFT Puspokszilagy (1976-)Trombay (1954-)Tarapur(1968-)Rajas than (1972-)Kalpakkam (1974-)Narora(1991-)Kakrapar(1993-)Kavir Ghom-desert (1984-)Negev DesertRokkasho(1992-)

AlmatyKurchatov(1996-)Ulba(1996-)Tschuj (1965-)Baldone(1961-)Maquixco(1972- )Kishinev (I960-)Kanupp(1971-)PINSTECH (1969-)Rozan(1961-)Baita-Bihor(1985-)Sergiev Posad,Moscow reg. (1961-)

Sosnovyi Bor, Leningrad reg.Kazan, TatarstanVolgogradNijnyi NovgorodIrkutskSamaraNovosibirskRostovSaratovEkaterinburgUfa, BashkortostanCheliabinskHabarovskPelindaba(1969-)Vaalputs(1986-)ElCabril(1992-)SFR(1988-)Oskarshamn NPP (1986-)Studsvik(1988-)ForsmarkNPP(1988-)RinghalsNPP(1993-)Dounreay (1957-)Drigg(1959-)Dnepropetrovsk centerL'vov centerOdessa centerKharkov center

Donetsk centerRWMC, INEEL(1952-)SWSA6, ORNL0973-)Disposal Area G, LANL (1957-)R^mu/^l 1LJ at 11 WCll^

South Carolina (1971-)200 East Area Burial Ground,Hanford (1940s-)

200 West Area Burial Ground.Hantord(iyVb-)

Richland, Washington (1965-)Savanah River Plant site (195 3-)

RepositoryConcept

ENSFS/ENSFENSFENSFENSFENSFENSFSNSFSNSFENSF

ENSFENSFENSFENSFENSFSNSFENSFSNSFSNSFENSFGR

ENSFENSFENSFENSFENSFENSFENSFENSFENSFENSFENSENSFENSFENSFSNSFSNSFENSFMCSNSFSNSFSNSFSNSFSNSFS/ENSFENSFENSFENSFENSF

ENSFS/ENSFS/ENSFSNSF

SNSF

SNSF

SNSFSNSF

38 IAEA BULLETIN. 39/1/1997

Country

UzbekistanViet Nam

Repository(date opened/dosed)

Tashkent (1960s-)Dalat(1986-)

Operation stopped or under closure

Armenia c

BulgariaEstoniaFrance

Germany

Russian Federation^

TajikistanUkraineClosedCzech Republic

ErevanNovi Han (1964-1994)Tammiku (f. Saku) (1964-1996)Centre de la Manche(1969-1994)

Asse (1967-1978)' Murmansk

Groznyi, ChechnyaBeshkekKiev center (-1992)

Hostim (1953-1965)

RepositoryConcept

ENSFENSF

BKTCCcNarENSFENSF

ENSFGR

ENSFENSFENSFENSF

MC

Country

HungaryJapanMexico

NorwayLithuaniaUnited States

SPECIAL REPORT

Repository(date opened/dosed)

Solymar(1960-1976)3

JAERLTokai (1995-1996)LaPiedrera (1983-1984)

Kjeller(1970-1970)4

Maishiogala (1970s-1989)Beatty. Nevada (1962-1992)IVf axcv FlatsKentucky (1963-1978)

ORNLSWSA 1 (1944-1944)3

ORNL SWSA 2 (1944- 1946)Shefield. Illinois (1967-1978)West Valley,New York (1963-1975)

RepositoryConcept

ENSFSNSFENSF

ENSFENSFENSF

SNSF

SNSFSNSFSNSF

SNSF

Notes on the table

Abbreviations: SNSF = Simple Near Surface Facility MC = Mined Cavity ENSF = Engineered Near Surface Facility GR = Geological RepositoryS/ENSF = SNSF and ENSF

'There are 77 repositories built to accommodate waste from Chernobyl accident.

^Repositories in Russian Federation started operation from 1961 to 1967.3Waste was moved to another repository (respectively, from Solymar to RHFT Puspokszilagy; and from ORNL SWSA-1 to ORNL SWSA-2).4Waste will be moved to a new repository (Himdalen) when constructed.

Definitions of selected terms

Low- and intermediate-level waste (LILW) is defined by the IAEA as radioactive wastes in which the concentration of or quan-tity of radionuclides is above clearance levels established by the regulatory body, but with a radionuclide content and thermal powerbelow those of high-level waste (i.e. about 2 kW/m3 ). LILW is often separated into short-lived and long-lived wastes. LILW arises fromthe operation of nuclear power plants (~500 m'/GWe year) and other fuel cycle facilities (-90 m3/GWe year from reprocessing, ~60000 m3/GWe year from uranium mining and milling), decommissioning of those facilities (5000 to 10 000 m3 from a one megawatt-electric station), and applications of radioisotopes. These wastes require proper management through treatment and conditioning andultimately through disposal.

Disposal is defined as the emplacement of waste in an approved, specified facility without the intention of retrieval. It may alsoinclude the approved direct discharge of effluents into the environment with subsequent dispersion (this article does not consider thisaspect). Again, the disposal by confinement and isolation includes land disposal, sea dumping (which was implemented by some coun-tries before it was banned by the London Dumping Convention), and others. (This article focuses on land disposal which is the pre-vailing current common practice.) In this context, the objective of disposal is to provide sufficient isolation of waste to protect humansand the environment and not to impose any undue burden on future generations. This can be fulfilled by applying multiple protectivemeasures to the disposal system taking into account interdependencies among elements involved in the system (i.e. systems approach).The protective measures require several levels of protection and multiple barriers to isolate the waste and to limit releases of radioac-tive materials, and to ensure that failures or combinations of failures that might lead to significant radiological consequences are of avery low likelihood.

Near-surface facility is a nuclear facility for waste disposal located at or within a few tens of meters from the Earth's surface. Thesetypes of facilities include trenches and engineered vaults.

Mined cavities are near-surface facilities constructed inside mines and caverns.Geological repository is a nuclear facility for waste disposal located underground (usually more than several hundred meters below

the surface) in a stable geological formation to provide long-term isolation of radionuclides from the biosphere.

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hole. Beginning in 1986 for safety reasons,the free space inside the vessels was filledwith metal matrix or polymeric compositematerials depending on the activity level andhalf-life of the spent SRS. Since 1995, thebore holes have been monitored to assesstheir performance. In the United States, spentSRS is categorized into different classes, andnot all of them are acceptable for near-surfacedisposal. Consequently, more conservativedisposal options, such as a geological reposi-tory or deep-augured holes are under consid-eration. Regardless of the technology used,the volume of spent SRS for this type of dis-posal may not be large enough to justify theeconomic or institutional costs associatedwith developing such a separate facility.

Improving existing disposal facilities.Some countries with existing disposal sys-tems are improving the operation of or reme-diating their disposal facilities to enhancetheir protective capabilities or to meet newregulations. Remediation can involve theretrieval of waste, in-situ immobilization ofwaste, in-situ decontamination, and in-situcontainment, such as installing cap, cutoffwalls, or floor barriers. In a number of coun-tries, including Germany, India, Bulgaria, andother countries in eastern Europe, safetyassessments have been or will be done as partof overall reviews of the performance ofexisting disposal facilities.

At the Morsleben repository in Germany, forexample, a safety assessment was done thatresulted in the formulation of new waste accep-tance requirements and quality-assurance pro-cedures. In Hungary, the Puspokszilagy reposi-tory, which had been accepting some uncondi-tioned waste together with packaged waste, hasestablished a guideline to accept only wastepackaged in 200-liter steel drums beginning in1997. In the UK, the Drigg repository under-went major improvements in the late 1980s.Leaving the old simple trenches closed, a con-crete vault was built for new types of wastepackages. Cutoff walls also were installed tolimit water flow in and out of the existing dis-posal trenches. In Norway, the remedial actionplan at an old near-surface disposal facility forlong-lived wastes involves digging out all wastepackages, and storing them at an interim surfacefacility. They will be moved to a rock cavernstorage and disposal facility to be built atHimdalen.

Long-term storage. In some countries,the option of long-term storage of radioactive

wastes is beginning to emerge. The optiondelays a decision on the wastes' ultimate dis-posal, in efforts to gain public confidence forimplementing disposal operations. However,the approach may require further considera-tions of regulatory and technical aspects.

At Norway's planned Himdalen site, hori-zontal tunnels are foreseen for disposal of short-lived LILW, as well as a separate tunnel for stor-age of wastes containing plutonium for an oper-ational period of about 30 years during whichthe stored waste will not be retrieved. When therepository is closed, a decision will be madeabout the waste's disposal at the site, based onoperational experience. A similar approach isseen in Switzerland where there is public con-cern over the irretrievability of waste to be dis-posed of at the planned Wellenberg repository.Authorities there are looking at the possibilityof keeping the facility open and controlled for aperiod of two or more generations until the timewhen the decision about the repository's closurecan be made.

Disposal costs. As disposal facilities havebecome technically more advanced, the costsof disposal have risen substantially. In somecountries, there is a general noticeable trendto minimize the generation of radioactivewastes as part of cost-reduction efforts.Additionally, less expensive solutions arebeing sought for disposal of VLLW, as notedearlier.

Recently, a working group was formedwith the Nuclear Energy Agency of theOrganization for Economic Co-operation andDevelopment on cost issues for LILW dispos-al. The group will identify cost components,analyze factors affecting disposal costs, andconsider the impact of disposal costs on theoverall price of generating electricity withnuclear power plants.

Public acceptance issues. As noted previ-ously, the issue of public acceptance has heav-ily affected the process of radioactive wastemanagement and disposal. In many countries,particularly industrialized ones, greater effortsare being made to overcome public percep-tions that are strongly negative. They includeenhanced communication programmes toimprove dialogue with local communities andthe public at large, and clearer demonstrationsof a commitment to scientific excellence,environmental protection, and long-term safe-ty in the siting and operation of repositories.

In some countries, financial incentiveshave been offered to communities accepting

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SPECIAL REPORT

waste disposal sites. The compensation shouldnot be considered as a risk premium, however,and safety issues must be discussed andresolved before starting any discussion on thecompensation. Examples of financial incen-tives include monetary payment as well asprovision of free electricity and greateremployment opportunities.

Regional-multinational repositories.Some countries are expressing interest inestablishing a regional-multinational reposi-tory whereby a site in a host country wouldaccept radioactive wastes from other coun-tries. The approach holds some economic,technological, and safety advantages, particu-larly for countries in the same geographicalregion. A prerequisite for such an approach isthe achievement of consensus among the rel-evant countries and regions, in particularregarding the transboundary movement ofradioactive wastes. The IAEA recently hasassessed some of the major factors involvedin the process of building consensus amonginterested countries on the various issuesentailed in such a regional approach.

In principle, the basic issues involved ina regional-multinational repository are notmuch different from those related to nation-al projects. But there are some qualitativedifferences related to the characteristics ofthe accepted wastes, the liability of partnercountries, the division of responsibilities,the application of any required safeguards,and the ownership and transfer of wastematerials.

Such regional repositories, which wouldbuild upon the best international practices inradioactive waste management, could givesome countries the option of not buildingtheir own national sites, thereby holdingdown the total number of repositories world-wide. Additionally, they could provide analternative for countries with unfavourableconditions for siting their own disposal sites.Disadvantages include the fact that a regionalrepository may increase transportation activi-ties. It also may be difficult to establish adurable system which can survive changingpolitical or institutional situations and whichcan assure the long-term collaboration of allpartner countries. One of the most challeng-ing tasks associated with such an approach isnegotiating agreements which provide partnercountries with assurances that all technical,political, and financial obligations will be ful-filled.

International co-operation

The disposal of low- and intermediate-level radioactive waste is based on proven andwell-demonstrated technologies. If reposito-ries are properly sited, constructed, and oper-ated — and the radionuclide contents of thewaste are controlled and limited — safety canbe satisfactorily assured for long periods oftime. This can be done by applying multipleprotective measures, including engineered andnatural barriers, and operational and institu-tional controls.

Within the IAEA's Member States, greaterreliance is being placed upon multiple engi-neered barriers for safety and environmentalprotection, and for building public confidence.Additionally, emphasis is being placed onsafe and reliable operation systems forremote handling, sheltering, and tracking ofwaste packages. At the same time, affordablesolutions are being sought for the safe dispos-al of categories of wastes containing very lowlevels of radioactivity, whose volumes arelarge. Greater attention also is being given toissues related to the safe disposal of wastescontaining naturally occurring radioactivematerials, the management and disposal ofspent sealed radiation sources, the costs ofdisposal, public acceptance, the improvementor remediation of existing disposal sites, thelong-term safe storage of wastes, and the pos-sible establishment of regional-multinationalrepositories.

Overall, countries, especially industrializedcountries, are experiencing slow progress indeveloping new repositories with respect totheir siting and licensing. These steps typical-ly involve extensive technical reviews by theregulatory body, public hearings, and complexregulatory and legal procedures.

In developing countries, the situation is dif-ferent. Most of them do not generate largeamounts of radioactive wastes yet require tech-nical assistance and guidance to establish suf-ficient infrastructures and capabilities for safe-ly managing and disposing of wastes. Throughits various technical and research programmes,the IAEA is supporting co-operative projectsand activities toward these ends. As moreradioactive waste disposal facilities are putinto operation around the world, the transfer oftechnology and expertise to developing coun-tries will continue to be of vital importance inhelping them to build up their capabilities inthis field.

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