Modelling Radioactivity in the Environment, Volume 4

439 Pages·2003·7.054 MB·English

by  E.M. Scott

MODELLING RADIOACTIVITY
IN THE ENVIRONMENT
RADIOACTIVITY IN THEENVIRONMENT
AcompanionseriestotheJournalofEnvironmentalRadioactivity
SeriesEditor
M.S.Baxter
AmpfieldHouse
ClachanSeil
Argyll,Scotland,UK
Volume1:PlutoniumintheEnvironment
(A.Kudo,Editor)
Volume2:InteractionsofMicroorganismswithRadionuclides
(F.R.LivensandM.Keith-Roach,Editors)
Volume3:RadioactiveFalloutafterNuclearExplosionsandAccidents
(Yu.A.Izrael,Author)
Volume4:ModellingRadioactivityintheEnvironment
(E.M.Scott,Editor)
MODELLING RADIOACTIVITY
IN THE ENVIRONMENT
Editor
E. Marian Scott
DepartmentofStatistics,UniversityofGlasgow,
Glasgow,G128QW,Scotland,UK
2003
AMSTERDAM–BOSTON–LONDON–NEWYORK–OXFORD–PARIS
SANDIEGO–SANFRANCISCO–SINGAPORE–SYDNEY–TOKYO
ELSEVIERSCIENCELtd
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Contents
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Section1:Modelsandmodelling
1. DesignandevaluationofenvironmentalradioactivitymodelsbyE.M.Scott. 1
2. ModellingthedispersionofradionuclidesintheatmospherebyA.Mayall . . 13
3. Modellingradioactivityinthemarineenvironment:Theapplicationofhydro-
dynamiccirculationmodelsforsimulatingoceanicdispersionofradioactivity
byI.H.Harms,M.J.Karcher&H.Burchard . . . . . . . . . . . . . . . . . . 55
4. RadioactivityintheterrestrialenvironmentbyG.Pröhl. . . . . . . . . . . . . 87
5. Modelling radionuclidetransportin the geologicalenvironment:a case study
fromthefieldofradioactivewastedisposalbyW.R.Alexander,P.A.Smith&
I.G.McKinley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
6. RadioactivityinlakesandriversbyL.Håkanson&L.Monte . . . . . . . . . 147
7. RadioactivityinaquaticbiotabyT.G.Sazykina . . . . . . . . . . . . . . . . . 201
Section2:Modellingapplications
8. Modellingthedispersionofradionuclidesinestuarineenvironments:theOdiel
riverestuarybyR.Periáñez&J.M.Abril . . . . . . . . . . . . . . . . . . . . 223
9. Predictingtransferofradionuclides:soil–plant–animalbyN.Crout,N.Beres-
ford&A.Sanchez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
10. PathwaysofanthropogenicradioactivityintheNorthernOceansbyI.H.Harms
&M.J.Karcher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
v
vi Contents
11. Modelling the behaviour of radiocaesium in forest ecosystems by G. Shaw,
R.Avila,S.Fesenko,A.Dvornik&T.Zhuchenko . . . . . . . . . . . . . . . 315
12. Mathematical and numerical approaches in performance assessment for ra-
dioactivewastedisposal:dealingwithuncertaintybyJ.C.Helton. . . . . . . 353
13. The Chernobylaccidentand aquaticbiota by I. I. Kryshev,T. G. Sazykina&
A.Kryshev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
Concludingremarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417
IndexofAuthors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
SubjectIndex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Foreword
E. MarianScott
Whyisabookonmodellingenvironmentalradioactivitynecessary?
Thereare manyreasonswhy sucha bookis necessary,perhapsthe mostimportantbeing
that:
(a) modelling is an often misunderstood and maligned activity and we hope that this book
canprovide,toabroadaudience,agreaterunderstandingofmodellingpowerbutalsoof
someofthelimitations,
(b) modellersandexperimentalistsoftendonotunderstandandmistrusteachother’sworkyet
theyaremutuallydependent,inthesensethatgoodexperimentalsciencecandirectgood
modellingworkandvice-versa;wehopethatthisbookcandispelmistrustandengender
improvedunderstanding,
(c) thereisanincreasingrelianceonmodelresultsinenvironmentalmanagement,yetthereis
alsooftenmisuseandmisrepresentationoftheseresults.Wehopethatthisbookcanhelp
tobridgethegapbetweenunrealisticexpectationsofmodelpowerandtherealisationof
whatispossible,practicableandfeasibleinmodellingofenvironmentalradioactivity;and
finally,
(d) modellingtools,capacityandpowerhaveincreasedmany-foldinarelativelyshortperiod
oftime.Muchofthisisduetothemuch-heraldedcomputerrevolution,butmuchisalso
duetobetterscience.Itisusefultoconsiderwhatgapifanystillremainsbetweenwhatis
possibleandwhatisnecessary.
Mathematicalmodelsaregeneraltoolsthatsynthesiseobservationalandexperimentaldata,
allowpredictionsofbehaviour,andprovideinputtodecision-makingprocessesintheirfield
ofapplication.Assuch,theyaresimplificationsofacomplexrealityandareimprecise,with
many sources of uncertainty. Models are developed to approximate or mimic systems and
processesofdifferentnatures(e.g.physical,environmental,socialoreconomical),andareof
varyingcomplexity.Manyprocessesaresocomplicatedthatphysicalexperimentationistoo
time-consuming,tooexpensiveorsimplyimpossible.Asaresult,investigatorsrequiremodels
tosimulateandexploretheseprocesses.
Mathematicalmodelsforradioactivityintheenvironmentarenodifferentfromthegeneral
models. They too are needed and used to describe the behaviourof a radionuclidewithin a
vii
viii E.MarianScott
possiblycomplexenvironmentalsystem.Theytoomayincludephysico-chemicaldescriptions
oftheprocesses(andrates),areusedtotesthypothesesconcerningenvironmentalbehaviour
andtoevaluateimpactassessment inresponseto anthropogenicinducedchange(eitherreal
or hypothetical)in a quantitative and objective manner. Theyalso form part of radiological
assessmentsbyprovidingpredictionsofconcentrationsofradionuclidesinthefoodchainand
ultimately,throughmodellingingestionand inhalation,to predictionof dose and biological
harm.
Inthedevelopmentofthemodel,themodellermustworkwithanimperfectandincomplete
descriptionof the physicaland biologicalsystem. Mathematicalmodels incorporatefactors
and parametersaimed at characterising the processes being investigatedand are commonly
composedofaseriesoflinkedequations(oftendifferential).
Themodellermustselectfeaturesandprocessestobeparameterised,hemustchosehowto
derivethe necessary equationsand thusmust synthesise sometimes conflictingevidence.In
thedesignofthemodelstructure,themodellermustacceptthatthereisnocorrectmodeland
thatacceptablepredictionsarepossiblefromquitedifferentmodels.Hemustalsoacceptthat
apparentlysmallchangesmaygeneratelargeeffects.Thesemakemodelcreationsomething
akintoanartalthoughfoundedinscienceandimposealimitontheconfidencethatauserhas
inthemodel.Further,modelsandmodellersmustcopewithnaturalintrinsicvariabilityand
impreciseobservation.Theymustassessandaccommodatetheuncertaintiesassociatedwith
thenaturalprocesses,decidehowbesttoincorporatethemintothemodels,howtodealwith
imprecisioninmeasurementandhowtopresentthecompletepackagetodecision-makersand
managers.
1. Aboutthisbook
Justasanenvironmentalmodeltypicallywillbecomposedofanumberoflinkedsub-models,
representing physical, chemical or biological processes understood to varying degrees, this
volumeincludesaseriesoflinkedchaptersexemplifyingthefundamentalnatureofenviron-
mentalradioactivitymodelsinallcompartmentsoftheenvironment.Aclassificationscheme
for the modelswould concludethat mostof the modelsare deterministic, some are mecha-
nisticanda fewaredynamicandstochastic.Themodeldomainofapplicabilityrangesover
theshortterm(days)tothelongterm(thousandsofyears)(asinwasterepositorymodelling,
Chapters5and12)andfromthenearfield(afewkilometres)tothefarfield(manythousands
ofkilometres)(asingeneraloceanmodelling(Chapters3and10)).Modelshavebeenused,
forexample,topredictlevelsofCs-137onpastureoverseveralseasonalcyclesfollowingthe
Chernobylpower plant accident(see Chapters 4 and 9); to modelthe global distribution of
Chernobylfalloutinlakesandrivers(Chapters6and7),tomodeltechnologicallyenhanced
naturalradioactivity(dischargefromphosphateprocessingin estuariesin Chapter8) andto
modelthedispersalofaradioactivepollutantdischargedintotheKaraSeafromdumpednu-
clearwaste (see Chapter 10).The model,dependingon its purposeandfield ofapplication,
will include manydifferentprocesses, the sub-processesof which may operate at quite dif-
ferenttimeandspacescalesandforthemodellertherewillbeachoiceofwhichprocessesto
modelexplicitlyandhowtoparameterisetheseprocesses.Thechaptersinthisbookpresent
thediversityandcommonalityofmodellingandthrowsomelight,wehope,ontheprocesses
Foreword ix
involvedinmovingfromproblem(hencepurpose)throughscientificknowledgetoconceptual
solutiontoultimatelypracticalandusefulmodellingtool.
In thisbook,the differentauthorswere asked to describemodelswithin a givenenviron-
mentalcompartment(atmosphere,oceans, lakes and rivers,and the terrestrial(andgeologi-
cal)environments).Theywereaskedtobringtogetherandillustratethemodeldevelopment
processesin these compartments,as well as to describe the currentmodellingpractices.Fi-
nally, they were then asked to illustrate and expand on the more methodological work by
describingandexploringanumberofcasestudies,i.e.toshowtheuseandpracticalityofthe
modelintherealworld.
Thecasestudieschaptersareextensive,variedanddetailed,allowingabreadthofmaterial
dealingwithissuesincludingscaleofmodel(local/global,overshort/longtimes),complexity
(1D–3D),validation and parameter estimation, sensitivity and uncertainty.Many are linked
specificallytoamethodologicalchapterandtherearemanyplannedandunplannedconnec-
tionsbetweenthechapters.Theapplicationshavebeendrawnfromsomeofthemostsignif-
icant environmentalradioactivity issues of recent times. We hope that they encapsulate the
bestcurrentpracticesandlookforwardtosomeofthenewdirections.
Initsentirety,thebooksummarisesthecurrentstateoftheradioactivitymodellingartand
scienceandpresentsaseriesofextendedcasestudiesconcentratingondifferentenvironments,
differentobjectivesanddifferentapproaches.
Acknowledgements
My thanks are due to a number of people. First, to Murdoch Baxter, the series editor and
myfriend,forcontinualencouragement,adviceandassistance.ItisdoubtfulifIwouldhave
embarkedon this task withoutmy experienceas an associate editor of the Journalof Envi-
ronmental Radioactivity under his editorship. Secondly, to all the authors for all their hard
workinputtingtogetherthesechapters;withoutthem,therewouldbenobook.Allgraciously
agreedtocommittheirtimeandeffortandalthoughthegestationperiodwaslongerthanorig-
inallyenvisaged,Ihopethattheyconsiderthefinishedproducttohavebeenworthwhileand
worththewait.