V. Vorobiev, V. Kiselev, M. Korzhov, A. Krylov, N. Zhilina€¦ · V. Vorobiev, V. Kiselev, M. Korzhov, A. Krylov, N. Zhilina Ecological Modeling Dep., IBRAE, B. Tulskaya 52, Moscow,

Computer system for estimation and analysis

of radioactive contamination of surface water

V. Vorobiev, V. Kiselev, M. Korzhov, A. Krylov, N. ZhilinaEcological Modeling Dep., IBRAE, B. Tulskaya 52, Moscow, RussiaEmail: [email protected]

Abstract

The given work presents description and practical representation of thespecialized system of computer models for estimation of consequences ofradioactive accidents and other releases of radioactive substances to anenvironment (water systems). A number of models are integrated in specializedGIS (geographical informational system) if that is required by problems beingsolved. The variety of models (model for river, for small simple lake, forcomplicated basins, etc.) on prediction of concentration in various types of waterobjects is stipulated by large zones of influence of nuclear reactors. The modelsare integrated in the number of confined chains that enable full calculation froman accident parameters to resulting pollution and health harm. On the base ofcalculated results appropriate actions are recommended. System is «open» so itcan be expanded and improved by other models. A prototype of decision supportsystem for emergency radioactive pollution based on the computer modelscomplemented with regulative documents database is also presented. The systemwill support decision making on population protection in an emergency situationand «what if» process through radioactively dangerous object projecting. Forcreation of the computer bank of models and decision support system moderninformation technologies are used. Validation and verification of computermodels are carried out now. Some of models were verificated on the Chernobylaccident contamination data. Consequences of nuclear submarine accident(1985) in the Chazhma Bay (near Vladivostok) are analyzed now and models areverificated with the aid of this data.

Transactions on the Built Environment vol 42, © 1999 WIT Press, www.witpress.com, ISSN 1743-3509

466 Marine Technology

Introduction

There are plenty of methods and models for evaluation of radioactivecontamination of water objects, for prediction of behavior of radionuclides inbasins, for estimation of population exposure, for analysis of possible healthharm, for development of appropriate recommendations. The aim (and the result)of given work is an integration of several ecological and mathematical modelsinto confined chain.Radionuclides emission —> Surface contamination —»Basin contamination -> Radionuclides behavior prediction -> Estimation ofinternal and external exposure -> Development of appropriate recommendations

Such integration makes this system convenient for evaluation ofradioactive accident consequences, for calculation of limits of radioactiveemission into basins, for estimation of possible harm from various radioactivelydangerous actions. This system should be convenient tool for decision supportfor radioactive safety professionals responsible for environment and populationprotection.

For this purpose we have developed the system, which has following mainadvantages:1. The models are integrated into the confined chain.

No data other than hydrology data and appropriate information about anaccident (atmospheric discharge, wastewater discharge etc) is necessary forradioactive doses and radioactive risk prediction and for developing ofrecommendations.

2. The system enables a customer to use experimental data for furthercalculations instead of intermediate calculation results, which permits toincrease accuracy of final results (if experimental data are available).

3. All subsystems are open. It is possible to use them jointly with other models.It enables a customer to use most appropriate and convenient (fromcustomers point of view) models in each particular case.

4. Quick "from start to end" prediction is possible.5. Computer models included in the system are easy to use and have user-

friendly interface.6. The system is flexible. It supports decision-making and enables "what if

process. It also gives you opportunity to evaluate sensitivity of results toinput data.

7. It is possible to get final and intermediate results (at any stage) for any ofexternal processing.

8. Models included in the system are generic and correctly describeradionuclides behavior in basins of some type in general. And they do notuse specific characteristics of a particular object.

9. Coefficients, parameters, etc, that are necessary for confined work of thesystem, are available as an appropriate databases.

10. Each model operates in wide range of input data.


Marine Technology 467

Description of the system

Experimental or calculation data on surfacecontamination from an atmospheric

advection model or from another source

Wastewater discharges data etcGeographical-informationalsystem Komponovka

Model for radionuclidesbehavior prediction

(simple basins) BasinModel for complicatedwater objects (based onPrinceton Ocean Model)

Model InterEstimation of internal and externalexposureEvaluation of risks,Development of recommendations

ResultsRadioactive contamination prognosisEstimation of dosesEstimation of risksRecommendation on protectionmeasures

Figure 1. System structure.

The system consists of the following elements:1) Geographical informational system Komponovka (based on Mapinfo).2) The model for prediction of radionuclides behavior in simple low-flow

basins (Basin).3) The model for estimation of internal and external exposure for various groups

of population (water ways of exposure). This model evaluates radioactiverisks and develops appropriate recommendations (Inter).

4) Model for a river (under development).5) Model for complicated basins (based on the Princeton Ocean Model

improved by PNNL). Linking of this model to our system is carried out now.Full description of the models you can find in [1] and [2].

For system to operate hydrological data is necessary. Computer hydrologicalmaps do exist nowadays. More precise information concerning basins (type ofsediments, water humidity etc) could be found in special hydrological reference-books (see [3] for example). On the preparatory stage this information istransferred to computer databases. Also information about different populationgroups rations and types of external activities is collected and stored.



Qpanta OfibfiKiw anpoc -Jafiflwa -HjcrpoftKM QKHO fcapra

Figure 2. Water objects coloured depending on their contamination.

If necessary models parameters, doses limits etc could be corrected also. Allthese actions are carried out on the preparatory stage (before an accident). Afterthat the scheme of operation of the system varies from different circumstances. Itdepends on accident parameters, information available, type of water object,customer's requirement. In fact:1) Radionuclides can get into hydrological network as a result of an accident or

as a result of regular discharges.2) Radionuclides can get into hydrological network by different ways:

atmospheric discharge, wastewater discharge etc.3) The contamination data can originate from two sources - experimentally

measured or predicted by a model. For example a model of atmosphericadvection can calculate atmospheric discharge.

4) Characteristics of water objects vary substantially. We subdivide them ontothree types: complicated water object, simple basin, river.

On the next stage parameters of an accident or a discharge are alreadyknown. Format of input data and the list of water objects that should be thesubject of prediction is also known at this stage. First of all, if data (experimentalor calculated) concerning contamination presented spatially (with no link towater objects), then Komponovka determines intersection of contaminated areawith local hydrology and prepares information about contamination of eachspecific water object. After that depending on type of a water object model forradionuclides behavior prediction is chosen. For simple water objects the Basinmodel is used, for large complicated water objects POM model should be used,



for rivers - a river model. Calculated by Komponovka integral data concerningcontamination of a specific water object and collected previously generalinformation about the water object are transferred to chosen model forcontamination prediction. On this stage other ways of contamination (wastewaterdischarge, washing out of contaminated riverbeds and water collection area,secondary contamination of water from sediments) could be taken into account.Then contamination of the water object is predicted for some period of time.Resulting contamination of water and sediments is transferred to the model"Internal and external exposure" Inter. After that according to collectedpreviously data on population groups rations etc doses are estimated. Theestimation results are compared to appropriate limits. On the base of that data"module of warnings and recommendations" analyzes critical (contributingmost) ways of exposure and issues appropriate warnings and recommendations ifnecessary.

The results (finite and intermediate) can be presented as graphs or maps.They also can be printed or reviewed interactively.

The system can operate without any of its parts or with another externalmodel attached. For example the operation without Komponovka module isconvenient in case when a source of contamination data are - experimentalmeasurements of water and sediments contamination instead of a model ofatmospheric propagation.

The system is designed for MS-WINDOWS 95/98. It is developed withthe Mapbasic 4.0 (geographical part) and VISUAL BASIC 5.0. The system hasbilingual (russian and english) interface. The prototype of the system was used inrealization on Command and Headquarters Training "Polyarnye Zori - 95". ThisPractical Game was held by EMERCOM and UN Department of HumanitarianAffairs and took place in Apatity, Murmansk region, May 29 - June 2, 1995. Infuture supposed in future to give attention to more complex models, additionalprocesses, updating and development of the databases. It was a foundation laidfor development of similar systems for other types of contamination (chemicalfor example).

Models description

Computer base model for radionuclides' behavior prediction for simplebasins contaminated due to accident or regular discharge (BASIN).

From the large spectrum of models we have chosen the model described in [1].The reasons are following:1) This model was developed for basin's type that is prevailing in Russia.2) Chernobyl accident experience was taken into account while building of the

model.3) This model is supplied with real coefficients and parameters necessary. So it

can operate with minimal input information.



Esthwaite Lake, water, Cs-1 37, Bk/m

250

• Exp.(epillim neon)

•Exp.(gypolim neon)

• Model

Days after accident

Figure 3. Example of comparison of calculation results to experimental data.

4) The model allows to predict basins contamination in cases of nonrecurrentdischarge, chronic discharges, combination of nonrecurrent and chronicdischarges. It is supposed that nonrecurrent contamination is connected withan accidental atmospheric discharge or wastewater discharge. Chroniccontamination may be connected with contaminated river waters inflow, withwashing out of contaminated riverbeds and water collection area, withrecurrent regular discharges.

The method of calculation of radionuclide concentration in water andsediments is based on the well practically worked out two-chamber model ofideal mixing radioactive impurity. The model reflects exchange processesbetween radionuclides dissolved in water, sorbed on suspended particles andsited on sediments. Main processes of transfer of radionuclides: running wateroutflow out of the basin bounds; sedimentation of suspended particles; stirringup of contaminated sediments; diffusive exchange of radionuclides betweenwater and sediments, sludge etc.

The model was verified on the experimental data on contamination(resulting from Chernobyl accident) of water and sediments of four lakes:Svyatoe Lake (Belorussia) [4], Bracciano Lake [5], Esthwaite Lake andWindermere Lake [6]. Comparison shows that the model correctly reflects theresults in general. But in some experimental points one can see deviations. Suchdeviation could be explained by some inadequacy of experimental dataconcerning hydrological surrounding, errors in measurements, and somedisadvantages of the model. Nevertheless comparison results shows that the



model is applicable even to stratified basins for average and long timepredictions.

Model for complicated basins

We are going to use for this purposes well-known three-dimensional numericalocean model (Princeton Ocean Model) improved by Pacific Northwest NationalLaboratories (PNNL) [2]. Verification of this model based on the data on thecontamination resulting from submarine accident in the Chazhgma Bay [7] iscarried out currently. Linking of this model to our system is also in process now.

Computer model "Internal and external exposure (water ways)" /INTER

For decision making on radioactive protection along with radioactivecontamination prediction, estimation of possible health harm for differentpopulation groups is required. For that purpose prediction of doses andradioactive risks is necessary. To find easiest way of reducing negative effects,one should find out what contributes most to final doses. These problems aresolved by the model "Internal and external exposure". This computer model wasdeveloped according to Nuclear Safety Regulations (NSR-96) [8]. Similarmodels are recommended by U.S. Nuclear Regulatory Commission,Bundesministren Des Innern (Germany).

This model is designed for prediction of doses of internal and externalexposure (related to water objects), for estimation of risk from stochastic effects,for developing of appropriate recommendations. The model estimates effectivedose (dose on an entire body) and equivalent doses for different organs of humanorganism. It compares results to norms established by Nuclear SafetyRegulations (NSR-96) [8]. This model takes into account the following ways ofexposure related to water objects: exposure from consumption of contaminatedfood and drinking water (internal exposure); exposure from swimming, boating,staying at the beach, etc (external exposure). The model requires no informationconcerning contamination which cannot be calculated by models for predictionof radionuclides behavior in water objects (in our case this is radionuclidesconcentration in water and sediments).

This computer model is "quick". So it can be used in extreme situations.One of the advantages of the model is its ability to estimate contribution toresulting dose of every radionuclide, every type of food and every type ofexternal activity. So one can determine critical (contributing to resulting dosesmore than others) ways of exposure. It enables reducing of doses with minimalside effects. For example, to avoid consumption of type of food responsible forthe largest part of resulting doses may be the easiest and the cheapest way ofpopulation protection.

Model is easy to use, supports decision making and enables and"what if process.



Warnings and recommendations development

Warnings and recommendations are developed according to Nuclear SafetyRules (NSR-96):

There is a collection of controlled parameters and limit values for them,established by [8]. If one of the parameters exceeds its limit a warning is issued.A collection of radiation protection measures is also recommended by [8]. Therealso established limits for doses prevented by every measure. There are twolevels of measures and doses prevented by them respectively - "Level A" and"Level B". If doses prevented do not exceed "Level A" it means that there is noreason to take an action if this action is associated with local disruption ofregular business and social activity. If doses prevented exceeds "Level A", butdo not exceeds "Level B" decision should be made taking into account particularconditions and local circumstances. If doses prevented do exceed "Level B"appropriated protection measures must be carried out even if they disrupt regularbusiness and social activity.

Computer programs' screen samples

Half life time of CS-134Annual consumption ofVolume activity of CS-134 In waterBioaccamulation factorConcentration of: CS-134 h Crabs'Annual Inflow of CS-134 , with r "Crabs'dose conversion factorAge factorIntestines absorbttonAnnual dose for CS-134Annual dose recjevedwlh, . •, "Crabs'Total annual doseRadionuclides are sorted by , half life timeRadtonudk* : CS-134Age group: • ' 10-15 years -, t : iOrgan: . The restFood: "Crabs'Gender .women

Change age I Change organ | Change gender |

2.061998

9.15516E-07kg

; BM

9.15516E-079.15516E-071.9E-08

!Bk" Zv/Bk

1.1

5.321245E-08 mZv1.9265256,11 mlv5.3268S4E-08 mZv

Radionuclides Foods Ust

Figure 4. Internal exposure screen (model Inter).



Figure 5. Screen of input data (model Basin).

Figure 6. Contamination of water and sediments.



1. Vorobiev, V.A., Kiselev, V.P., Korgov, M.Y., Krylov, A.L. Computerj) /.•; if models for prediction radionuclides behavior in surface water.Russian Academy of Science, Nuclear Safety Institute (IBRAE),Moscow, 1997.

2. Mellor, G.L., Users Guide for a three-dimensional, primitive equation,numerical ocean model, Princeton University, Princeton, 1996

3. El shin, Y.A., Surface water resources of USSR. Basic hydrologicalcharacteristics. Kolsky peninsula, Hydrometereological publishing house,Leningrad, 1965.

4. Vorobiev, V., Gorbachev, A., Kanevsky, M., Nosov, A., Panchenko, S.,Evstratov, E.,Medved, J., Hitrikov, V., Computer base model forradionuclides' behavior prediction for simple basins contaminated due toaccident or regular discharge, Nuclear Safety Institute RAS (IBRAE),Moscow, 1994.

5. Monte, Fratarcangeli, S., Pompei, F., Quaggia, S., Andrasi G., Modeling thebehavior ofCs-137, Cs-134 and SR-90 in lake systems, (results of researchcarried out using radioactivity measurement data collected following theChernobyl accident), ENEA, ISSN/0393-6309, RT/PAS/89/31.

r, *.f-po>in-<n c Hilton, J., Jenkins, A. - A dynamic model of cesiumtransport in lakes and their catchments, Wat. Res., Vol.25, 4, pp. 437-445.,1991.

7. Sivintsev, Yu., Vysotsky, V., Danilyan V., Radioecological consequences of' )acci(!u*on;!uc!earsu!^(;:rinein'h ' ' A; /Energy, v.76, N.2,, pp. 158-160, Moscow, February 1994

R Nuclear Safety Regulations (NSR - 96), Goskomsanepidnadzor of Russia,


Documents

V. Vorobiev, V. Kiselev, M. Korzhov, A. Krylov, N. Zhilina€¦ · V. Vorobiev, V. Kiselev, M. Korzhov, A. Krylov, N. Zhilina Ecological Modeling Dep., IBRAE, B. Tulskaya 52, Moscow,