Comparison of waste management aspects of direct disposal of spent fuel and reprocessing

Comparison of waste management aspects of direct disposal of spent fuel and reprocessing


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Construction of data sets
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Commission of the European Communities
a »~ ­■■ ­a
Comparison of waste management aspects of
direct disposal of spent fuel and reprocessing
Construction of data sets
EUR 14036 EN ν
Commission of the European Communities
nuclear science
and technology
Comparison of waste management aspects of
direct disposal of spent fuel and reprocessing
Construction of data sets
R.J. Greathead
Systems Division
233 High Holborn
London WC1V 7DJ
United Kingdom
Contract No FI1W­0251
Final report
This report was prepared for the European Energy Community's cost­sharing research programme on radio­
active waste management and disposal under contract No FI1W­0251 'Comparison of waste management
aspects of direct disposal of spent fuel and reprocessing ­
Construction of data sets'
Publication of this report has been supported by the Value programme for the dissemination
and utilization of the results of EC research and technological development activities
(Dissemination of Scientific and Technical Knowledge Unit, Directorate­General Information Technologies
and Industries, and Telecommunications, Commission of the European Communities, Luxembourg)
PARL EUROP. Biblioth. Science, Research and Development
1992 EUR 14036 Ε N.C.
m Published by the
Information Technologies and Industries, and Telecommunications
L-2920 Luxembourg
Neither the Commission of the European Communities nor any person
acting on behalf of the Commission is responsible for the use which might
be made of the following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1992
ISBN 92-826-4285-2
© ECSC-EEC-EAEC, Brussels · Luxembourg, 1992
Printed in Luxembourg CONTENTS
1.1 Perspective on Study
1.2 Background and Description of CODDAR 1
1.2.1 Background
1.2.2 Overview 2
1.3 Model Definition and the Choice of Comparisons 4
1.4 The Structure of the Report 6
2.1 Introduction
2.2 Scenarios 8
2.3 Data Sources and Interpretation 11
2.3.1 Introduction
2.3.2 Inventory Data2
2.3.3 Storage Data 13
2.3.4 Transport Data
2.3.5 Preconditioning and Conditioning Stages
(Stages in the Direct Disposal Route) 14
2.3.6 Reprocessing, Interim Storage of Liquor and
Vitrification (Stages in the Reprocessing Route) 1
2.3.7 Disposal5
2.3.8 Public Collective Doses from Effluents 16
2.4 Weighting Sets 1
2.5 Costs9
2.6 Methodology of Data Set Construction and Model
Testing 20
2.6.1 Method
2.6.2 Model Testing1
3.1 Introduction
3.2 The Impacts of the Various Scenarios 2
3.2.1 Costs Impacts Reprocessing vs Direct Disposal2g Options4 Direct Disposal Options6
3.2.2 Total Impacts 2
3.2.3 Short Term Radiological Impacts 28 Reprocessing vs Direct Disposal9 2g Direct Disposal4 Summary9
3.3 CODDAR and the Model 30 CONTENTS (cont'd)
1.1 Perspective on Study
The work described in this report has been carried out under CEC
contract FI1W-0251-UK by YARD Ltd and is part of a CEC funded
programme examining and comparing the management options
for the back end of the Light Water Reactor fuel cycle ("Third EC
Programme on Radioactive Waste Management and Disposal -
Task 1 - Item 3).
The study uses a computer modelling tool called CODDAR to
compare the costs and environmental impacts associated with
radioactive waste management aspects of direct disposal of spent
fuel and reprocessing.
Data was principally derived from reports prepared by other
contributors to the CEC programme, notably NUKEM, CEA,
BNFL and NRPB, who provided descriptions and analyses of the
cost and radiological impacts for direct disposal, reprocessing and
a number of variants on these two main routes.
The study has resulted in comparative data on:
a) costs (absolute and discounted to take account of investment
strategies over the duration of the treatment and disposal
b) radiological impact;
c) overall impact in which the cost and radiological impacts
are combined using sets of weighting factors chosen to
reflect various attitudes towards disposal (concern for cost,
concern for local heath, etc).
For the purposes of the CEC programme a reference case was
specified by the CEC to ensure a common basis for the component
studies. In this case, a PWR reactor park operating for 30 years at
20 GWe at a burnup rate of 33 GWd/tU is considered. This will
generate 600 tU per year for reprocessing or direct disposal in the
form of 1300 REP 17 χ 17 CPI type fuel elements, each containing
462 kg of Uranium. Major variants on this case have been
considered by the contributing organisations, including a small 6
GWe reactor park, a large 60 GWe park, a high burn (45 GWd/tU)
option and delayed reprocessing.
1.2 Background and Description of CODDAR
1.2.1 d
CODDAR was initially developed under a previous contract with
the CEC (FI1W-0133-UK) and has its provenance in DISPOSALS, which is a micro-VAX based computer model developed by CAP
Scientific under contract to the Department of Environment (UK).
DISPOSALS determined the optimum disposal methods, in terms
of minimised weighted total impact (cost and radiological), for
MLW and LLW waste streams in the UK. CODDAR is a simpler
PC based model which incorporates the concepts of total weighted
impacts developed in DISPOSALS, but, unlike DISPOSALS, does
not automatically optimise the disposal route; i.e. it calculates the
total weighted impact for a scenario which must be fully defined
by the user.
Under the previous CEC contract, CODDAR was developed and
tested using simple notional data sets. Under the current
contract realistic data sets have been derived from the literature
and incorporated into the model and various runs carried out to
compare scenarios under differently weighted and discounted
conditions. More rigorous testing and checking have also been
performed. A number of errors have been corrected, but no major
features have been modified or incorporated.
1.2.2 Overview
The following is a brief overview of CODDAR and the incorporated
concepts. A revised Users Guide to the code provides detailed
information on setting up and executing the model (Ref 1).
The CODDAR modelling tool has been designed to allow the rapid
comparison of radioactive waste management aspects of direct
disposal of spent fuel and reprocessing. The model calculates the
cost and radiological impacts resulting from four main types of
activity, i.e.:
treatment (reprocessing or conditioning);
transport; and
disposal of spent fuel.
The radiological impacts from the:
transport; and
of secondary (low and intermediate level) waste streams which
arise from storage and treatment of spent fuel are also calculated.
2-Figures 1.1 and 1.2 show in more detail the waste management
stages for direct disposal and reprocessing that have been
incorporated into the model. For the direct disposal route, the
spent fuel can be stored at reactor (AR) or away from reactor
(AFR). This is followed by preconditioning, further storage,
conditioning and then transport to the disposal site. For the
reprocessing route, the spent fuel is stored at reactor followed by
transport and storage away from reactor, reprocessing, storage of
the reprocessing liquor, vitrification, storage of the vitrified waste
and then transport to the disposal site.
Data for each waste management stage is entered into the model
to allow cost and radiological impacts to be calculated. The
impacts calculated for each stage are combined through the
multi-attribute hierarchy shown in Figure 1.3. The cost and
radiological impacts at each level of the hierarchy are multiplied
by weighting factors and added together to give the weighted
impacts at the next higher level. The overall impact at the top of
the hierarchy gives a measure of the impact from the direct
disposal or reprocessing scenario being considered.
Weighting sets, designed to reflect different attitudes and levels of
concern towards cost, radiological impact, etc (see Section 2.4) are
comprised of the weighting factors to be applied at each point in
the attribute hierarchy.
To define a waste management scenario the following data must
be entered:
the waste inventory, including volume arising;
the unit cost and radiological impacts for the waste
management options being considered;
the weights used to combine the cost and radiological
impacts; and
the rate of discount on costs to be applied.
The main features of the model are shown in Figure 1.4.
The figure shows the processes involved in defining a scenario.
An identifier for the scenario must be entered (an existing
identifier can be selected to modify a scenario). This will result in
the display of a schematic diagram showing the direct disposal or
reprocessing stages (cf. Figures 1.1 and 1.2). Each of the stages
can be selected in turn and a data set for the stage created or
selected from a list of previously generated data sets (a data set
can be used in more than one scenario). On exiting the scenario,
CODDAR automatically calculates and sums the impacts. Having defined a scenario, histograms and reports can be
produced. A scenario report can be produced which describes the
data sets used to define a scenario. A solution report can be
produced which gives details of the impacts for a scenario.
Decision trees and histograms of costs and short term radiological
impact can be used to compare the impacts of two scenarios.
1.3 Model Definition and the Choice of Comparisons
CODDAR has been used to generate 6 main Direct Disposal
scenarios and 8 main Reprocessing scenarios as indicated below:
CEC Reference case for reactor park
BNFL/NRPB data [R.8]
CEA data [R.1]
6 GWe reactor park [R.6]
High burn up of fuel [R.7]
Delayed Reprocessing
Interim storage in casks [R.5] me in vaults [R.4]
Interim storage in pools
rods consolidated [R.3]
rods unconsolidated [R.2]
Direct Disposal
CEC Reference case for reactor park
(NUKEM) Option 1
Cask storage prior to preconditioning
Vault storage prior tog
Disposal at Gorleben [D.l] l at Auriat [D.5]
(NUKEM) Option 2 [D.3] )n 3 [D.4]
6 GWe reactor park [D.6]
(See below for identity codes of scenarios generated, shown in bold
in above list).
These scenarios are shown schematically in Figure 1.5 and
described in more detail in.Section 2.2.
This is done by linking appropriate data sets for the different
storage, transport, treatment, disposal and secondary waste
processing stages comprising each scenario, as outlined in the
previous sub-section.
Any one of five weighting sets (A, B, C. D and X - described in
detail in Section 2.4) can be applied to each main scenario.
Similarly, any rate of investment discount (See Section 2.5) can be
applied to a scenario and for the purposes of this study, rates of
í>, 3%, 5% and 10% were studied, chosen because they represent