Sea Dumping of Radioactive Wastes

J.M. BewersMarine Chemistry DivisionDepartment of Fisheries and OceansBedford Institute of OceanographyDartmouth, Nova Scotia

AbstractThis paper outlines the history and regulation of sea dumpingof packaged low-level radioactive waste in the ocean. Theprocedures by which dumping limits are established andperiodic safety evaluations conducted under internationalauspices are described. Particular reference is made to recentnegotiations on the future of the practice within the LondonDumping Convention and the role played by Canada in thisforum, and in others relevant to this subject.

ResumeCet article esquisse I'histoire et la regimentation de la pratiquedu deversement en mer de dechet radioactif de faible activite.Les methodes utilisees pour etablir les reglements interna­tionaux et les evaluations periodiques de securite sontdecrites. Reference particuliere est faite aux negotiations surIe futur de la pratique dans Ie forum de la Convention deLondres et Ie role du Canada ici et dans les autres organisa­tions internationales pertinentes.

IntroductionThe use of the ocean for waste disposal is a subject ofsome controversy. Some regard the ocean as a legiti­mate receptacle for wastes arising from human andindustrial activities; others wish to preserve the oceanin as pristine a state as possible and therefore opposeany deliberate use of the oceans for waste disposal.Debates over the use of the ocean for waste disposalhave intensified during the last four decades, i.e. sincethe end ofthe Second World War, both within nationaljurisdictions and in the international community. In­creased public awareness of environmental damage,

hazards to human health and the desirability ofimproving the level of environmental protection fromthe adverse effects of human and industrial activitieson the one hand, and, on the other, of the need todispose of a variety of wastes arising from anthropo­genic activities has contributed both to the polariza­tion and intensity of these debates. This paper isconcerned with one facet of this subject - that relatingto the sea dumping l of low-level radioactive wastes inthe ocean that has been carried out under the provi­sions of the London Dumping Convention and also,largely, under the auspices of the Nuclear EnergyAgency of the Organization for Economic Cooperationand Development (oEeD).

The two main routes of deliberate disposal ofradionuclides into the ocean being practiced now arethe direct discharge into the sea of low-level liquidwastes from the reprocessing of nuclear fuels for therecovery of plutonium, and the dumping of packagedlow-level radioactive waste into the deep ocean. Athird route of deliberate disposal being considered forfuture use is the emplacement of high-level radioactivewaste within, or on, the seabed. Use of this latteroption currently seems unlikely and, in any event, itis at least a decade distant. The word 'deliberate' isused here to discriminate between these activities andthe incidental introduction of radionuclides into theocean through fallout from nuclear weapons explo­sions. This latter fallout has both increased the marineconcentrations of certain natural nuclides, such astritium and radiocarbon, and introduced a variety ofpredominantly artificial (fission-product and activa­tion-product) nuclides into the marine environment.The particular avenue of radioactive waste disposalthat has been the subject of most international debateis the dumping of packaged low-level radioactivewaste into the deep ocean, which has been practicedsince the end of the Second World War. In this paper,the history of such dumping, the manner in which ithas been regulated, and some aspects of the recent

Keywords: radwaste, sea dumping, ocean disposal, international regulation, oceanography, nuclear safety, radiationprotection, London Dumping Convention.

290 NUCLEAR JOURNAL OF CANADA /1:4/ pp. 290-301

debate about its future within the London DumpingConvention are described.

Table 1: Aggregate Radioactive Waste Dumping in the NortheastAtlantic Ocean 1948-1982 (Source: Templeton and Bewers, 1986)

The History of Radioactive Waste Dumpingin the OceanDumping of low-level radioactive waste in the oceanhas been carried out since 1946. Between 1946 and1967, the United States dumped approximately 4,000TBq of radioactive waste into the Pacific and AtlanticOceans and the Gulf of Mexico. This includes about1,200 TBq of activation products in the reactor pres­sure vessel of the Seawolf submarine propulsion unit.About 90% of this total activity was dumped in theNorth Atlantic at the '2,800m site' located at 38°30'N,72°06'W. Packaged radioactive waste has also beendumped at ten sites in the northeast Atlantic in thevicinity of 46°N, 1~W by seven western Europeancountries since World War II. The location of the mostrecently used NEA-approved dumpsite is shown inFigure 1. A summary of the recorded amounts ofradioactive waste dumped in the northeast Atlanticbetween 1949 and 1982 is given in Table 1. Thedumped low-level wastes come from nuclear powerplants, other nuclear fuel cycle operations, medicine,research, industry and the decontamination and de­commissioning of plant and equipment. The waste is ofa similar nature to that arising from non-nuclearindustrial, medical, and research facilities, except that

20° 15°

Figure 1: Location of the North-East Atlantic Dumpsite.

(18.4 kCi)(1,027kCi)

(405 kCi)

142,275 tonnes6.8 x IOZ TBq3.8 x 104 TBq1.5 x 104 TBq

"1975-1982 only. Tritium in previous years included in beta / gammaactivity.

Average activity Average activitydumping rate dumping rate

Nuclide TBq per year Nuclide TBq per year

24'Am 1.28 10' 21OPO 4.09 Hr'14C 5.04 101 238pU 6.23

244Cm 1.13 Wool 239pU 2.48 W58CO 4.13 101 240pU 1.22 1016OCo 2.54 102 24'PU 1.49 103

134CS 3.27 101 242pU 3.40 10-1

137CS 1.34 IOZ 226Ra 1.2555Fe 1.61 101 355 6.093H 2.43 103 90Sr 8.04 10'

1251 1.20 101 234U 2.89 10-2

54Mn 7.32 235U 5.72 10-1237Np 1.95 10-1 238U 2.92 10-2

Gross massAlpha activityBeta /gamma activityTritium"

it includes items having radionuclide contamination insurficial and chemically-incorporated forms and in­duced radioactivity. Accordingly, this material re­quires a range of special handling, treatment, anddisposal arrangements. The composition of the wastesdumped has varied year by year. Plutonium isotopesand 241Am account for over 96% of the aggregate alphaactivity and tritium and 241pU accuunt for over 87% ofthe aggregate beta-gamma activity dumped. The re­mainder of the long-lived beta-gamma activity is com­posed principally of the fission products 90Sr and 137Csand the activation product 60Co. The average dumpingrates of a number of individual nuclides during theperiod 1978-1982 are shown in Table 2. The wastepackages are designed to provide shielding and con­tainment of the waste during handling and transporta­tion, and to ensure that the packages reach the seabed(at depths equal to, or greater than, 4000 metres)without losing their integrity. The integrity of thepackages after descent to the seabed is not assumed orrequired in the development of regulations. However,some types of package can maintain their integrity,and restrict the release of contained radionuc1ides, forseveral decades after dumping. Figure 2 provides anexample of the manner in which the waste packagesappear on the ocean floor although, in this instance,the container is of u.s. origin and was dumped at the2,800-metre site in the Atlantic Ocean in the early1960s.

Table 2: Average Rates of Individual Nuclide Dumping During thePeriod 1978-82 (Source: NEA, 1985b)

40°

45°

.-/

~~APPROX380 NAUTICAL MILES

/(700 km)

10°

45°

35°

40°

50°

291

Figure 2: Radioactive waste container on the floor of the AtlanticOcean. The United States Environmental Protection Agency isacknowledged for providing permission to reproduce this photograph.

Regulation of Sea Dumping of Radioactive WasteThe political and administrative framework withinwhich sea dumping of radioactive waste is carried outinvolves two international bodies. The first of these isthe London Dumping Convention (LOC) which wasfinalized in 1972 and entered into force in 1975 [IMO,

1982]. This is the major international instrument for theformulation of international regulations for sea dump­ing activities and has now been ratified by 61 States.The other international body is the Nuclear EnergyAgency (NEA) of the Organization for Economic Co­operation and Development (OECD), within which dataon the actual amounts dumped are collated and thesafety of such disposals assessed multilaterally on aquinquennial basis. The NEA created, in 1977, aMultilateral Consultation and Surveillance Mecha­nism [NEA, 1977] for these purposes and, in allrespects, the NEA activities are consistent with theintent and principles of the LOC. All countries involvedin dumping in the Northeast Atlantic during the lastdecade (Belgium, the Netherlands, Switzerland, andthe United Kingdom) are parties to this agreement,while other non-dumping NEA countries (Canada,Denmark, Finland, France, the Federal Republic ofGermany, Ireland, Italy, Japan, Norway, Portugal,Spain, Sweden, and the United States) have beenwilling to participate in associated site-suitability re­views and safety assessments carried out under theauspices of the NEA. However, it is within the forum ofthe LOC, or in connection with this Convention, thatthe major international negotiations respecting radio­active waste dumping at sea have occurred. As will beshown, the debate on the future of this practice withinthe LDC has intensified since 1983.

292

The London Dumping ConventionThe London Dumping Convention (formally referredto as the Convention for the Prevention of MarinePollution from Dumping of Wastes and Other Matter,London, 1972) was created following a recommenda­tion of the First Stockholm Conference on the Environ­ment and has as its objective the prevention of marinepollution through dumping at sea. The Convention iscomposed of a series of principles or articles and threetechnical annexes. The first annex (Annex I) contains alist of substances that are proscribed for dumping inthe ocean, except as 'trace amounts' in other materials,and includes inter alia organohalogen compounds,mercurycompounds, cadmiumcompounds, persistentplastics, crude oil and associated wastes, and high­level radioactive material - deemed unsuitable fordumping at sea because of the human health and otherhazards associated with such disposals. Annex II listsmaterials for which special care must be exercised inrespect to their disposal into the marine environmentand includes inter alia wastes containing significantamounts of lead, copper, zinc, organosilicon com­pounds,2 cyanides and fluoride~. It also includesradioactive wastes and all other radioactive matter notincluded in Annex I. Annex II also specifies that theInternational Atomic Energy Agency (IAEA) is the'competent international authority' for specifying tothe LOC what types of radioactive materials fall withinAnnexes I and II. Annex III contains a list of criteriaupon which an evaluation of the effects and permissi­bility of a proposal to dump material should beevaluated.

The Role of the International Atomic Energy AgencyThe major role that the IAEA has played in the LDC asthe 'competent international authority' for radioactivematters under the Convention has been to providedefinitions of high-level radioactive wastes 'unsuit­able for dumping at sea' (i.e. the definition of Annex Iradioactive materials). This definition of the boundarybetween Annex I and Annex II radioactive matter istermed 'the IAEA Definition.' The IAEA also appends tothe Definition, a set of 'Recommendations' that containits advice as to manner in which radioactive materialshaving radioisotope concentrations below those spec­ified in the Definition (Le., Annex II wastes) can bedumped and how the safety of such dumping might beassessed and ensured. These periodic 'Definition andRecommendations' documents have been issued bythe IAEA in 1975,1978 [IAEA, 1978] and, most recently,in 1986 [IAEA, 1986]. The Agency has also developedadditional guidance on the subject of sea dumping ofradioactive wastes as well as ancillary material relatingto the administration of the LDC in respect of radioac­tive materials. Examples of such guidance are IAEA

Safety Series Nos. 61 and 65 which deal, respectively,with the overall framework for the control of waste

disposal into the marine environment [IAEA, 1983] andenvironmental assessment methodologies that can beapplied to sea dumping of radioactive wastes [IAEA,

1984]. This, then, describes the role and responsibili­ties of the IAEA under the LOC. Before going into a moredetailed explanation of the contents of the 'Definitionand Recommendations' documents, the relevant prin­ciples of radiological protection advanced by theInternational Commission on Radiological Protection(ICRP) are outlined briefly below.

Principles of the International Commission onRadiological ProtectionThe entire consequences of the generation, use, anddisposal of radionuclides are regulated on a relativelysimple set of principles devised by the InternationalCommission on Radiological Protection [ICRP, 1977]and, in the main, adopted by national regulatoryauthorities such as the Atomic Energy Control Boardof Canada (AEcn). These principles are as follows:1. Justification. No practice, involving potential exposures to

radiation, should be adopted unless there exist clear netbenefits to society, i.e. that the overall benefits outweighthe overall detriments (such as exposures to radiation) tothe society affected. Justification applies to an entirepractice (e.g. investment in the fission power industry)rather than to components of that practice such asuranium mining.

2. Compliance with dose limits. Limits of exposure to radiationfor both radiation workers and members of the public arelaid down.

3. Optimization. Exposures to radiation should be kept aslow as reasonably achievable, taking technical, social,and economic factors into account. Thus, exposuresshould be reduced by technical means, or through the useof alternative options for the handling and disposal ofradioactive wastes, so that the overall exposures resultingfrom the activity or sub-activity are as low as economicallyand socially justified. The application of this principlerequires complex balancing of scientific, economic, andpolitical factors but, in many cases - such as the compari­son among options for radioactive waste disposal- thesebalances can be somewhat simplified.

In practice, justification, as a conscious and deliber­ate process, is seldom rigorously exercised because theneed for regulatory activity has usually followed frominvestment in the practice, rather than preceded it.Therefore, for all intents and purposes, the majorover-riding principles that must be adhered to in theauthorization of any sub-practice, such as the disposalof radioactive wastes arising from the nuclear powerindustry, are compliance with dose limits and optimi­zation. At this juncture, the concept of 'collective dose'needs to be introduced. The dose consequences of apractice, for optimization purposes, are assessed onthe basis of the summation of all individual exposures,referred to as the collective dose. Thus while the upper

limit of individual dose is important for the protectionof so-called 'critical groups' of individuals, the actualradiation detriment from a practice must consider thesum of all exposures to all exposed individuals.

The IAEA Definition of High-Level RadioactiveWastes under the LDCThe basic process by which the Definition of 'wastesunsuitable for dumping at sea' is derived is composedof an evaluation of the 'capacity' of a hypotheticalocean basin, about the size of the North Atlantic, toreceive radionuclides without violating the appropri­ate dose limits established by the ICRP for members ofthe public. The introduction of radionuclides into theocean through dumping is counterbalanced both byradioactive decay and by the removal of those radio­nuclides to ocean sediments within which the radio­nuclides eventually become isolated from the bio­sphere. These processes, namely introduction, removal,and decay, can be modelled in such a way as to relatethe concentrations of individual radionuclides in va­rious sectors of the ocean to the rate ofwaste dumping.The pruCt:~~~ uf deriving the definition is thus one ofcalculating the rates of release (at the ocean floor) ofeach potential constituent radionuclide, which resultsin an equilibrium concentration field which, in turn,corresponds to a radiation exposure (dose) to indivi­dual members of critically exposed population groups(critical groups) equal to the ICRP individual dose limit.The oceanographic model relates the marine concen­tration fields to rates of release of individual nuclides.While equilibrium concentrations can be reached rela­tively quickly for short-lived nuclides, which decaybefore they can be transported great distances, suchequilibria for the very long-lived nuclides are onlyobtained on time scales comparable with the half-lifeof the nuclides, which can be much longer than oceanmixing time scales. Therefore, the model has to predictmaximum concentration fields that are obtained aftersome preconceived time of continued dumping prac­tice, or assume that the practice continues indefinitely,and predict equilibrium fields that in some cases areonly obtained on geological time scales. The choicebetween these options is referred to in the nextparagraph of this paper. The oceanographic model iscoupled to a radiological model that accounts forroutes of human exposure from the marine environ­ment, such as the consumption of seafood, recreationaloccupation of beaches, and the inhalation of marineaerosols (Table 3). Other potential exposures associatedwith future activities like deep-sea manganese noduleextraction are also considered. The limiting rates ofrelease that correspond, for each constituent nuclide,to the dose limit are referred to as 'release rate limits'and these constitute the basic values for the establish­ment of a definition of high-level radioactive wasteunsuitable for dumping at sea. For administrative

293

Table 3: Exposure Pathways Considered in the Derivation of the IAEA Definition (Source: IAEA, 1986)

Pathway Symbol Intake rate or occupancy time Other parameters

Actual pathwaysSurface fish consumptionMid-depth fish consumptionCrustacea consumptionMollusc consumptionSeaweed consumptionSalt consumptionDesalinated water consumption

Suspended airborne sedimentsMarine aerosols

BoatingSwimmingBeach sedimentsDeep sea mining"

Hypothetical pathwaysDeep fish consumptionPlankton consumption

FISH-S

FISH-M

CRUST

MOLL

WEED

SALT

DESAL

SED

EVAP

BOAT

SWIM

BEACH

MINE

FISH-D

PLANK

Ingestion rate600 g·d-I •

600 g·d-I •

100 g·d-I

100 g·d-I

100 g'd-I

3 g·d-I

2000 g'd-1

Inhalation rate23 m 3 . d-I

23 m 3 . d-I

Occupancy times5000 h·a-I

300 h'a-I

2000 h'a-1

500 h'a-I

Concentrations10 f.l.g' m-3 water, particlesb

10 g'm-3 vapour

Modifying factors-y0.2 130-yl 130.5-yO.5 [30.5

-y 1 13°

• Reduced to 300 g·d-I when summing doses over actual pathways so that the total seafood intake is600 g'd-I

, made up of 300 g of mid-depth or Burface fiBh, and 100 g each of crustacea, moluscsand seaweed.

b Made up of 0.25 f.l.g·m-3 fine coastal sediment particles, 3.3 f.l.g·m-3 dried sea salt particles and6.6 f.l.g·m-3 particle associated water.

C Not included in reference sets of calculations.

purposes, some simplification of the manner ofpresen­tation has been made by the Agency such that theDefinition takes the form both of release rate limits,and of derived activity concentrations for a smallgroup of classes of radionuclides, with the class limitdefined by the most critical or limiting nuclide in eachclass, based on assumptions as to the limiting mass ofradioactive waste to be dumped in any year (Figure 3).

Both the oceanographic and radiological bases ofthese models have been revised since the formulationof the previous Definition and Recommendations in1978. In particular, the oceanographic models havebeen quite substantially refined. The Definition pro­duced in 1978 took account only of radioactive decayas a means of radionuclide removal and ignoredparticle scavenging and settling processes that resultin the eventual association of nuclides with deepocean (pelagic) sediments. It was previously assumedthat, for exposure pathways originating in water,nuclides remained wholly within the water phase;while for pathways originating in pelagic sediments, itwas assumed that radionuc1ides released from dumpedcontainers became wholly associated with pelagicsediments. The model's results were, consequently,somewhat conservative or pessimistic. The revisedoceanographic models used for the derivation of therevised definition in 1986 included, for the first time,representations of particle scavenging and sedimenta­tion processes for the removal of radionuclides fromthe ocean. Additional nuclides to those considered in

294

the 1978 Definition, and a more realistic time scale forthe practice, were also introduced. Whereas, in theoceanographic model used for the derivation of theprevious Definition, the practice had previously been

DEFINITION OF HIGH-LEVEL RADIOACTIVE WASTE OROTHER HIGH-LEVEL RADIOACTIVE MATTER UNSUITABLE

FOR DUMPING AT SEA

For the purposes of Annex I to the Convention, high-level radioac­tive waste or other high-level radioactive matter unsuitable fordumping at sea is defined as follows:

(1) Irradiated reactor fuel; liquid wastes from the first solventextraction cycle of chemical reprocessing of irradiated reactorfuel, or equivalent processes; and solidified forms of such waste;and

(2) any other waste or matter of activity concentration exceeding:(a) 5 x 10-5 TBq kg-I for alpha-emitters;(b) 2 x 10-2 TBq kg-I for beta / gamma-emitters with half-lives of

greater than 1 year (excluding tritium); and(c) 3 TBq kg-I for tritium and beta / gamma-emitters with half­

lives of 1 year or less.

The above activity concentrationB Bhall be averaged over a grossmass not exceeding 1,000 tonnes.

Materials of activity concentration less than those in (2) shall notbe dumped except in accordance with the provisions of theConvention (Annexes II and III thereto) and the Recommendationsset out in this document. The maximum dumping rate into a singleocean basin of volume atleast 1017m3 shall not exceed lOS kg per year.

Figure 3: The 1986 revision of the IAEA definition and recommenda­tion. Source: IAEA, 1986.

assumed to continue unaltered for 40,000 years (withvery long-lived nuclides not attaining steady-statedistributions in that time), the most recent Definitionwas based upon models that invoke equilibrium fornuclides of half-life less than about 100 years, andseparately predict maximum concentrations achievedby longer-lived nuclides following 1,000 years ofcontinuous dumping practice. The choice of 1,000years for the length of practice results from evaluationsof the probable life of the nuclear fission pruC~iSiS aiS ameans of obtaining electrical power which is estimatedto be ca. 500 years [UNSCEAR, 1982]. In the radiologicalmodels, revised values for the annual limits of intake(AU) of nuclides, and changes to the recommendedmethods of calculating exposures to populations, havebeen introduced, and this has resulted in some changesin the details of the calculations. An additional andimportant change in the radiological models was theimposition of a reduced value for the individual doselimit. In the Definitions produced by the IAEA up toand including 1978, this limit was set at 5 mSv (milli­Sieverts), but the most recent definition used 1 mSvonthe basis that prudence dictated that, for exposuresreceived over long periods (as could be the case forexposures resulting from sea dumping activities) froma single practice (ocean dumping), a lower individualdose limit was more appropriate as a limit to exposuresfrom the practice. To a large extent this latter changehas been allowed for by an amendment to the mannerin which the Definition is expressed. In the 1978Definition the release rate limits were defined as thoseapplicable to the introduction of nuclides from allsources excepting natural background and fallout fromnuclear weapons tests. In the most recent (1986)Definition (Figure 3) the release rate limits applyspecifically to ocean dumping.

The Definitions produced by the IAEA become anintegral part of the LOC requirements upon its Con­tracting Parties and define what radioactive materialscannot be dumped in the ocean under its provisions.As already stated, the Definition is accompanied by aseries of recommendations that spell out under whatconditions radioactive materials can be considered forocean dumping and how the safety of such practicesmay be assured. Thus, the Recommendations apply tothe manner in which the 'special care' provisions ofAnnex II of the LDC are to be satisfied. These Recom­mendations, which are also based upon the principlesof the ICRP, include sections on environmental assess­ment procedures; selection of dumping sites; packag­ing and transport procedures; control, surveillance,and monitoring of dumping activities, and their conse­quences. While these recommendations do not takethe form of binding conditions under the LOC, Contract­ing Parties to the Convention have agreed to satisfythe Recommendations to the extent possible. Itmustbestressed that the LOC merely lays down requirements

to which the competent national licensing authority ofa Contracting Party shall adhere. Therefore, in prac­tice, the actual licensing of a dumping operation isprovided by national authorities, although there is anafter-the-fact notification procedure within the provi­sions of the Convention. It is worthwhile now toprovide some more detailed explanation of the Recom­mendations before dealing with the manner in whichthe consequences of ocean dumping practices areassessed amI th~ iSaf~ty uf such practices assured.

The IAEA Recommendations Pertaining to theDumping of Radioactive Wastes Required byAnnex II of the LOeThe main features of the Recommendations are dictatedby the need to ensure that dose limits are not exceededand that optimization is carried out adequately forboth individual and aggregate sea dumps of radioac­tive materials. The Recommendations first define ap­propriate individual dose limits for the practice. Theystress that, since members of the public will bereceiving doses from other sources and activities, itcannot be assumed that a dose limit of 1mSv isintrinsically acceptable and that, for actual oceandumping activities per se, an upper bound to the doseshould be established. Since, however, no such boundhas yet been internationally established, individualnational authorities should use a dose limit that is'substantially less than 1 mSv.' The Recommendationsalso note that implementation of the optimizationprinciple should ensure that doses actually receivedfrom the practice will be only a small fraction of 1 mSv.(As will be seen, the subject of dose upper boundshas also been a topic in recent LDC deliberations on thefuture of low-level radioactive waste dumping prac­tices.) The recommendations then outline the criteriarelevant to environmental assessment and safety as­surance of both individual and aggregate dumpingoperations. They define exclusionary criteria relatingto the selection of dumping sites - these must besituated between latitudes SOON and 50°5 and haveaverage water depths greater than 4,000 metres, beclear of continental margins, islands, mid-oceanridges, ocean trenches, fracture zones, plate bound­aries, and areas of volcanic activity. In addition, theuse of dumping sites must not interfere with, orprejudice, other legitimate uses of the sea. Sites shouldtherefore be situated away from spawning areas,fishing grounds, the paths of submarine communica­tion cables, and potential ocean mining sites (for therecovery of mineral deposits). Finally, the number ofsites should be minimized and their location strictlydefined. Each site should be as small as practicable(and no greater than 104 km2 in area) and should not besubject to undue navigational hazards during dump­ing (i.e. coverage by satellite navigation should beavailable and the site should not be situated in

295

shipping lanes). The forms in which waste may bedumped and the packaging requirements are thenspecified and the manner in which transport andhandling activities are made consistent with IAEA

Transport Regulations [IAEA, 1973; 1985a] are de­scribed. This is followed by a short section on monitor­ing of the condition of the seas with respect to dumpedradioactive wastes in the vicinity of the dumping site.This section refers to relevant guidance provided inprevious IAEA [IAEA, 1983] and ICRP [ICRP, 1985]publications. The final sections of the Recommenda­tions deal with approval of the dumping ship and itsequipment; the role, duties, and authority of escortingofficers (who act as representatives of the nationalauthorities responsible for granting the dumping per­mit(s) and ensure that the holder of the dumpingpermit complies with its requirements and conditions);and international cooperation and observation. Thetext of these latter sections has remained largelyunaltered from those in previous IAEA Recommenda­tions. The section on international cooperation andobservation is relevant to the actual procedures of multi­lateral consultation and mutual safety assurance. TheRecommendations also advocate that dumping becarried out within the framework of regional coopera­tion agreements, as provided for by Article VIII ofthe Convention which states:

Furthermore, international cooperation in the selection anduse of dumping sites and multilateral or international obser­vation of loading and disposal operations is encouraged inorder to provide greater assurance that dumping operationsare carried out in accordance with the Convention and the

IAEA recommendations.

It is in this latter context that the NEA plays an impor­tant coordinating role in appointing escorting officersto sea dumping operations, and in conducting sitesuitability reviews and safety assessments associatedwith sea dumping of radioactive wastes in the North­east Atlantic, which has been the only continuousactivity of this kind in recent years.

Assessment of Consequences and Safety Assuranceof Radioactive Waste DumpingWhile the IAEA Definition and Recommendations setthe limits for the amounts of material that can bedumped and impose constraints as to the methods andlocations for sea dumping, safety assessments of seadumping operations are normally the responsibility ofindividual national regulatory authorities. Safety as­sessments for sea dumping of radioactive wastes in theNortheastern Atlantic Ocean are carried out multilater­ally under the NEA Multilateral Consultation Mecha­nism [NEA, 1977] as part of the quinquennial sitesuitability review process. These reviews are intendedto outline the features of the site that make it accept­able for dumping under the LDC / IAEA criteria, define

296

the nature and composition of the wastes dumped,cover the process of optimization (both in terms ofcomparisons between sea dumping and other options,and optimization specific to the sea dumping route ofdisposal), provide estimates of current doses andpredictions of future doses resulting from the practice,and demonstrate compliance with the provisions of theLDC (e.g., the provisions of Annex III) and the IAEA

Recommendations under the Convention. During theprocess of site SUitability review carried out in 1979[NEA, 1980], it was recognized that there existed anumber ofdeficiencies in the information pertinent tothe dumping site, which had the effect of limiting thedegree to which predictions of consequences could bemade. Estimates of dose consequences of aggregatedumping were based upon the same models used asthe basis for the 1978 IAEA Definition, which, asalready noted, were conservative. No attempt wasmade to estimate collective doses associated withdumping because of a conviction that such estimateswould be subject to extremely large (several orders ofmagnitude) uncertainties. This meant (and was stated)that the ICRP principle of optimizatiun could only beapplied to comparison among options, or within thedumping option itself, on a wholly qualitative basis byindividual national authorities. It was noted that itwould be desirable if this deficiency was correctedthrough the acquisition ofmore specific information onthe consequences of dumping, and of other disposaloptions, for optimization purposes. Consequently, inthe conclusions of the review, it was stated that: 'Thereis a need to develop a site-specific model of thetransfers of radionuclides, particularly on short andmedium time-scales, from the dump area to humanpopulations. Therefore, there is clearly a need tocontinue investigations presently aimed at improvingour knowledge of transport processes in the North­East Atlantic. It is recommended that a well definedprogramme planbe developed over the next 12 monthswithin the appropriate international framework tomeet this objective.' It was further concluded that'although the next assessment of the suitability of thepresent dump site will normally take place in fiveyears, it is recommended that a review of the scientificbasis for making the assessment and of the growingbody of knowledge about radionuclide transport pro­cesses in the North-East Atlantic be undertaken beforethat time.'

It was for these reasons that the NEA established, in1981, a Coordinated Research and EnvironmentalSurveillance Program (CRESP) [NEA, 1981]. The basis ofthis program was, predominantly, research to improvethe quality of the site suitability review and safetyassurance - particularly optimization - procedures.Safety assurance procedures used for sea dumping ofradioactive waste are based upon the use of predictivemodels to describe the results of various scenarios for

ocean disposal of radioactive wastes. Since, in the main,the radionuclides released from previously dumpedwastes are not detectable, even within the area of thepresent dumpsite, heavy reliance has to be placedupon the use of models that depict the processescontrolling the transport and behaviour of analoguestable elements. In fact, the weakest aspect of the mostrecent predictive models is the reliability of representa­tions of bio-accumulation and sediment-water parti­tioning processes for radionuclides that are vitallyimportant to an appreciation of the rates at whichradionuclides are able to enter exposure pathways forman, and the likely effects upon populations oforganisms. Significant individual exposures are manydecades, perhaps centuries, distant, but the scenariosused for safety evaluation conceive of ocean dumpingand direct discharges continuing for the life of thenuclear fission industry, currently projected to be 500years. Early and reliable prediction of consequencesis important if the ocean's resources are to be con­tinuously protected and the assimilative capacity ofthe ocean is not be be exceeded. The process ofrefining both the models for, and the process of, safetyassurance is not only dependent upon the willingnessof nations to be involved and to contribute to this kindof work but also on the acquisition of better under­standing of the processes of transport, behaviour, andbio-accumulation of radionuclides and their analoguesin the marine environment.

Oceanographic scientists and health physicists, re­spectively, have played a very important role in thedevelopment of 1) oceanographic models that takeaccount of physical, biological, and geochemical pro­cesses in the ocean; and 2) radiological models thatensure that all important routes of humane exposurehave been identified and considered in establishingthe suitability and safety of this practice. It must beremembered that the population potentially exposedto radiation resulting from this practice is extremelywidespread. Indeed, for the longer-lived nuclides, it isthe group containing heavy consumers of seafood inareas very remote from the northeast Atlantic that maybe potentially the most exposed. Several non-dumpingnations, including Canada, have adopted the stancethat they should participate in the assessment of suchpractices that have potential effects on Widespreadpopulations, not only to ensure that their own popula­tions are adequately protected but also to satisfyinternational obligations, such as those under theLondon Dumping Convention. Such involvement hashad a very significant impact on the nature of negotia­tions on the subject and has given these countries anenhanced reputation for objective assessment and assources of sound scientific advice. In the OECD / NEA

forum, countries such as Canada and the United Stateshave been very successful in stimulating substantialimprovements in the nature and quality of the safety

assessment process and have been willing to contrib­ute to the acquisition of scientific information that isrequired to improve the technical aspects of theseassessments. An example of these improvements hasbeen the CRESP program [NEA, 1981], which wasinstituted to improve the data and comprehensivenessof safety-assessment modelling. Within the researchaspects of this program particular attention has been,and continues to be, paid to the study of potentialvertical transport mechanisms that might significantlyshort-circuit the physical oceanographic transport ofdumped radionuclides to the ocean surface. The factthat there are a number of non-dumping countries thatwish to ensure that the consequences of sea dumpingare acceptable in terms of hazards to their own andother populations, and that, in some cases, mighteventually want to evaluate the sea dumping disposalas an option for their own waste management pur­poses, provides considerable incentive to dumpingcountries to do the best they can in safety assuranceand environmental surveillance. CRESP serves as one ofthe best and most scientifically rewarding multilateralprograms related to waste disposal anywhere in theworld. In the first four years of its existence it hasproduced extremely valuable information that hasenabled safety assessment and site suitability reviewsto be greatly improved. Details of the results of thisprogram can be found in recent NEA publications [NEA,

1983, 1985a].By the time of the 1985 Site Suitability Review the

state of knowledge regarding conditions at the North­East Atlantic dumpsite had improved considerably,thanks largely to data acquired through the CRESP

program. Furthermore, the development ofmodels forradiological assessment purposes enabled better esti­mates of maximum individual dose to be made, andcollective doses to be estimated. The record of thisreview [NEA, 1985b] contains chapters on the interna­tional framework for control of sea dumping, thequantity and composition of the waste dumped, adescription of the oceanography and biology of thesite, the results of monitoring around the site carriedout largely under CRESP, radiological assessment of thesite and, finally, a discussion of compliance with theinternational agreements governing sea dumping. Fromthe results of surveillance work, it was concluded thatthe incidence of radionucIides in biological samplesobtained from the dumping site were generally consis­tent with those expected from fallout and could not beattributed to radionuclides released from dumpedwastes. The major improvement in the radiologicalassessment aspects of the review were: 1) the use ofnew models to take into account the rates of nucliderelease from waste packages; 2) substantial refinementof oceanographic transport models, partly as a result ofwork carried out by a Working Group [GESAMP, 1983]of the United Nations Joint Group of Experts on the

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Scientific Aspects of Marine Pollution, which had alsoformulated the models adapted for use by the IAEA informulating the 1986 Definition; 3) the inclusion ofparticle-water exchanges; and 4) the use of reviseddata on sediment-water partition coefficients andbiological concentration factors developed jointly bythe IAEA and NEA (IAEA, 1985b). Previous assessmentshad assumed instantaneous release as soon as thepackages arrived at the seabed following dumping.The new waste package model introduces release ratesfrom five types of packages representing the range ofwaste packaging used in the past. The new radiologi­cal assessment includes realistic modelling of radioac­tive decay chains and detailed evaluation of thesensitivity of the models to uncertainties in the param­eterization. It was possible to improve the estimationof peak individual dose rates, and to calculate collec­tive doses and collective dose commitments, from pastpractices and for continued dumping, for a further fiveyears at rates ten times those of recent years.

The radiological impact of dumping activities ispredicted to be very low. The peak individual dosefrom past dumping is calculated to be 20 nSv.a-1

(nanoSieverts per year). It arises 200 years afterdumping starts and occurs by way of 239pU and 241Amaccumulation in molluscs. Moreover, this peak indi­vidual dose involves the assumption that molluscsfrom the Antarctic might be exploited for humanconsumption, which is currently not the case. Even ifdumping is continued for a further five years at tentimes the rates of previous years, the peak individualdose is only 100 nSv.a-1 occurring 200 years after thecommencement of dumping. The corresponding peakcollective dose rates are predicted to be 4.2 man Sv peryear for aggregate past dumping, and 42 man Sv peryear for past dumping combined with continueddumping for five years at ten times previous rates.These collective dose rates are dominated by theradionuclide 14C which, because of its long half-life,would need to be isolated and contained for very longperiods in order to reduce the collective dose from thisor other disposal practices. Sensitivity analyses indi­cated that the peak individual dose rates were mostsensitive to changes in the numerical representationsof particle scavenging of radionuc1ides, which confirmsprevious conclusions that this aspect of the modelling,namely the representation of particle scavenging pro­cesses and the manner in which water / particlepartitioning is parameterized and numerically repre­sented, is the most important for continued investiga­tion and improvement.

The most recent NEA review [NEA, 1985b] concludesthat the site is suitable for continued dumping for afurther five years at rates up to ten times those dumpedin recent years. If rates of dumping are proposed thatwould exceed ten times previous rates, the suitabilityof the site should be reconsidered before approval for

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these increased rates of dumping is given. It is alsorecognised that, before further dumping permits areissued, certain other aspects of the suitability of thedumping practice need to be considered, particularlyhow sea disposal compares, on environmental, social,economic, and technical grounds, with alternativedisposal options. This latter point stresses again theneed for greater attention to be paid to the optimiza­tion process and the requirement to demonstrate thatexposures are maintained at levels 'as low as reason­ably achievable' - the so-called ALARA principle em­bodied in the optimization process laid down by theICRP.

Recent Developments within the Forum of theLondon Dumping ConventionIn 1983, at the Seventh Consultative Meeting of theLOC, Kiribati and Nauru, Pacific island ContractingParties to the LOC, proposed an outright ban on thedumping at sea of any radioactive waste. After discus­sion, the meeting adopted a moratorium on furtherdumping pending a review, by an independent panelof experts, of the scientific and technical basis uponwhich dumping practices were regulated and theirsafety assessed. This panel, composed of expertsnominated by the IAEA and the International Councilof Scientific Unions (ICSU), subsequently submitted itsreport to the Ninth Consultative Meeting in September1985. The main conclusions of this report can besummarized as follows:

1. The present and future risk to individuals from past oceandumping of radioactive waste is extremely small. The riskof developing a fatal cancer or severe hereditary defect ispredicted to peak about 200 years in the future at a level ofless than 10-9 per annum. The most potentially exposedindividuals would be those consuming shellfish harvestedin Antarctic waters.

2. Notwithstanding the very small risk to individuals, theaggregate exposure to the global population from long­lived components of the dumped waste imply that thetotal casualties resulting from past dumping may be up toabout 1,000 spread over the next 10,000 years or so. Thedominant isotope responsible for this collective dosecommitment is 14c, with 239pU being the next mostimportant isotope, giving rise to a few per cent of the totalcollective dose. If the radiocarbon, and a few otherlong-lived radionuclides, were to be removed from thewaste before disposal in the ocean, the collective dosecommitment from future dumping operations would bevery much reduced. However, other means of disposal ofthese nuclides, other than very long-term containment,would result in comparable collective dose commitments.

3. The incremental dose from past dumping to individualmarine organisms on the sea-floor at the dumpsite, ornearby, will be significantly less than the dose that theorganisms receive from naturally-occurring radioactivity,

* In October, 1985, following the Ninth Consultative Meeting,Canada advised the LDC Secretariat that its vote against ResolutionLDC.21(9) had been an error and that Canada supported theResolution.

1. Agrees to a suspension of all dumping at sea of radioac­tive wastes and other radioactive matter to permit time forthe further consideration of issues which would provide abroader basis for an informed judgement on proposals forthe amendment of the Annexes to the Convention. Thissuspension will continue pending the completion ofstudies and assessments referred to in paragraphs 2 to 5hereunder;

2. Requests that additional studies and assessments of the

and hence is not expected to cause any detectable effectson populations oforganisms. Aresumption ofdumping ata rate an order of magnitude higher than previously mightcause damage to individual organisms, but would still notbe expected to affect an entire population significantly.

The Panel's overall conclusion, acceptable to theexperts, but not to national representatives present atits final, expanded, session, was that 'No scientific ortechnical grounds could be found to treat the option of seadumping differently from other available options whenapplying internationally accepted principles of radioprotec­tion to radioactive waste disposal.' However, the NinthConsultative Meeting of the LOC, after considering theExpert Panel's report, and after much debate, adoptedby a vote (the voting pattern is shown in Table 4) aResolution [LOc.21(9)] of which the operative partstates that the LOC:

Table 4: Voting Pattern on Resolution LDC 21(9) at theNinth Consultative Meeting

Some aspects (Paragraph 5) of the work proposedhere are being dealt with as part of the ongoing workprogram of the IAEA, others (Paragraph 3) are anexisting requirement on national authorities under theIAEA Recommendations, and others (Paragraph 6) arebeing considered in the context of future UNSCEAR orIAEA work plans. None of these items is in any wayurgent at the current rates of dumping. There isconsiderable merit in considering assessments of liabil­ity under international law (Paragraph 7) since this islikely to prove to be a very time-consuming task andone that might subsequently be applied not only toother ocean waste dumping practices but to a wholerange of practices that potentially affect other nations.It is difficult, however, to see how the harmlessness ofdumped waste (Paragraph 4) can be established whenrisk assessment is at the heart of the entire radiologicalprotection process. It is implicitly assumed that risk ofradiological harm increases in proportion to the dose

wider political, legal, economic and social aspects ofradioactive waste dumping at sea be undertaken by apanel of experts to complement the existing ExpandedPanel Report;

3. Requests that further assessments examine the issue ofcomparative land-based options and thc costs and risksassociated with these options;

4. Requests that studies and assessments examine the ques­tion of whether it can be proven that any dumping ofradioactive wastes and other radioactive matter at sea willnot harm human life and / or cause significant damage tothe marine environment;

5. Requests the IAEA to advise Contracting Parties withrespect to certain outstanding scientific and technicalissues relating to the sea dumping of radioactive wastes;specifically;(a) To determine whether additional risks to those con­

sidered in the revised IAEA Definitionand Recommen­dations justify re-examination of the definition ofradioactive wastes and other radioactive matter un­suitable for dumping at sea for certain individualradionuclides;

(b) To establish source (dose) upper bounds appropriateto the practice of radioactive waste dumping underthe Convention;

(c) To define quantitatively the exempt levels of radionu­clides for the purposes of the Convention,

6. Requests the Organization to approach internationalagencies to cstablish and maintain an inventory of radio­active wastes from all sources entering the marine en­vironment;

7. Calls upon Contracting Parties to develop, as envisagedin Article X, procedures for the assessment of liability inaccordance with the principles of international law re­garding state responsibility for damage to the environmentof other States or to any other area of the environmentresulting from dumping.

ArgentinaBelgiumGreeceItalyJapanPorhlgalUSSR

AbstainAgainst

Canada*FranceSouth AfricaSwitzerlandUnited KingdomUSA

For

AustraliaBrazilChileCubaDenmarkDominican RepublicFederal Republic of GermanyFinlandHaitiHondurasIcelandIrelandKiribatiMexicoNauruNetherlandsNew ZealandNorwayOmanPanamaPapua New GuineaPhilippinesSaint LuciaSpainSweden

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received without threshold, and therefore non-zerorisk is intrinsically assumed in any practice thatinvolves dissemination of radionuclides to the envi­ronment. The major subject of controversy within thewe has been Paragraph 2, to which some ContractingParties have strenuously objected on the grounds thatthe we has no right to deal with political and socialissues within the purview of sovereign state jurisdic­tions. Nevertheless, a procedure has been devised toform a new Contracting Party expert panel on issuesraised in Paragraph 2 during 1987. It remains to be seenhow these activities will impinge upon the future ofocean dumping of radioactive waste. It should benoted that the Canadian delegation proposed amend­ments to delete Paragraphs 2 and 4 from the resolutionprior to the vote and, when these amendments werenot adopted, voted against the resolution (Table 4).Subsequently, however, the Secretary of State forExternal Affairs, in a letter to the Secretary-General ofthe International Maritime Organization, pointed outthat the Canadian delegation had erred and thatCanada supported the resolution.

In view of the strong international controversysurrounding low-level radioactive waste disposal inthe ocean it is difficult to predict the future of thispractice. The current moratorium on such dumpingwhich has been in effect since 1983 will continue, andprobably be observed, until at least 1988, when thenext Consultative Meeting of the London DumpingConvention is to take place. Progress made in respectto the further evaluations proposed in the most recentLDC resolution on this issue will be reviewed at thattime. Meanwhile the United Kingdom, one of thecountries most affected by the moratorium, has carriedout and published an evaluation of various options forthe disposal of low- and intermediate-level solid radio­active waste (HMSO, 1986a] that would seem to point tocontinued U.K. interest in the sea dumping option forsome kinds of radioactive waste, although the practiceof waste dissemination to the environment has beenrecently criticized by the British House of CommonsEnvironmentCommittee IHMSO, 1986b]. Nevertheless,the strong front against sea disposal is bound tostimulate increased efforts to develop and provealternative, land-based, methods of disposal. Clearly,the final verdict on sea dumping of low-level radioac­tive wastes under international law is not yet in. Thedevelopments within the London Dumping Conven­tion during the next two years will probably decideboth the fate of this practice and the future of theConvention itself.

If sea dumping of radioactive waste is eventuallyproscribed through, for example, the allocation of allradioactive materials to Annex I of the Convention,some url!encv will be olaced uoon the definition ofso-callelde ;'inimis a~ounts ot'radioactivity. Unlesssuch a definition can be formulated it can be argued

300

that, since all substances, natural and anthropogenic,contain radionuclides, albeit of natural origin, dump­ing of any material should be prevented because it isintrinsically radioactive. In such an event, the formula­tion of exemption rules to permit materials to beconsidered for ocean dumping without conSiderationof their radioactive character would need to be formu­lated. This subject is also one that has been on thework program of the IAEA for several years. While it is arelatively simple matter to define levels of trivial dosefor the development of such exemption rules, it israther more difficult to convert dose to units ofconcentration that would be needed for practicalapplication. Such conversions would probably have tobe site-specific and, since most ocean dumping occursin the coastal zone, the variety of conversions requiredto account for the extremely large heterogeneity ofconditions in inshore areas will be large. Furthermore,the application of exemption rules in the context ofcollective dose requires more study.

ConclusionsAs with other nuclear industrial activities, radioactivewaste dumping has aroused strong feelings about thepotential dangers to humanandenvironmentalhealth.All recent assessments of the consequences of previ­ous dumping, and of continued dumping for a furtherdecade at similar rates, yield very small individualdoses to members of critical populations. The debateon the safety of the practice has consequently centredarOllnd the collective dose commitment and the associ­ated casualties worldwide. Certainly, the levels of riskassociated with the practice are small compared withlevels of involuntary risk currently assumed by mem­bers of a wide variety of societies [Allman, 1985]. Thereis, however, some merit in the argument that membersof certain societies not currently enjoying the benefitsof peaceful nudear energy (and indeed choosing notso to do) are potentially at risk in the sense that somecasualties in such societies are statistically probablebased upon the assumption of radiological harm beinga function of dose without threshold. These argu­ments are in many ways analogous to the common 'notin my backyard (NIMBY) syndrome,' but at an interna­tional level. Unless the current differences betweenthe dumping and objecting countries can be resolvedthrough the establishment of some mutually satis­factory compensation mechanism, the subject willcontinue to place considerable strains on the LDC.

Continued lack of consensus or mutually acceptableagreement might result in the impasse being ended bycertain nations unilaterally resuming sea dumping atsome time in the future. Whether this endangers thecontinued viability of the London Convention is amatter of conside;able concern to Canada and othercountries.

Notes

1. The use of the term 'dumping' in this paper is consistentwith that in the London Dumping Convention, wherein itis defined inter alia as meaning 'any deliberate disposal atsea of wastes or other matter from vessels, aircraft,platform~ or other man-made structures at sea.' Dumpingtherefore covers the introduction of waste material intothe sea from ships in packaged or unpackaged forms. Theterm 'sea disposal' is mafp gpnpfk and is used to coverboth dumping, as defined above, and discharges to theocean from land.

2. A recommendation to delete organosilicon compoundsfrom Annex II was adopted by the LDC in 1986.

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