Advanced processes for the treatment of low level liquid wastes at a pilot plant scale

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ISSN 1018-5593
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European Commission
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Advanced processes for the treatment of
low level liquid wastes at a pilot plant scale
Report
EUR 17446 EN European Commission
nuclear science
and technology
Advanced processes for the treatment of
low level liquid wastes at a pilot plant scale
'A. Bruggeman, 2C. Jones, 3R. Roofthooft, 4A. Severo
1SCK-CEN
Boeretang 200
B-2400 Mol
2AEA Technology
Harwell Laboratory
DidcotOXH ORA
United Kingdom
3Laborelec
Rodestraat 125
B-1630 Linkebeek
4LNETI-DPSR
Estrada nacional 10
P-2685 Sacavém
Contract No FI2W-CT90-0057
Final report
Work performed as part of the European Atomic Energy Community's
shared cost programme (1990-94)
on 'Management and storage of radioactive waste'
Task 2: Treatment of radioactive waste
Directorate-General
Science, Research and Development
1997 EUR 17446 EN A great deal of additional information on the European Union is available on the Internet.
It can be accessed through the Europa server (http://europa.eu.int.)
LEGAL NOTICE
Neither the European Commission 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, 1997
ISBN 92-827-9045-2
© ECSC-EC-EAEC, Brussels · Luxembourg, 1997
Reproduction is authorized, except for commercial purposes, provided the source is acknowledged
Printed in Luxembourg CONTENTS
Introduction 1
A. Part A Boron separation from PWR-waste 3
A.l Introduction and laboratory testing on simulant waste 5
A. 1.1 Introduction 7
A. 1.2 Theoretical background
A. 1.2.1 Electrodialysis
A. 1.2.2 Electrochemical ion exchange 11
A. 1.2.3 Distillation of boric acid6
A. 1.2.4 Reverse osmosis 2
A.l.2.5 Ion exchange
A. 1.3 Laboratory testing
A. 1.3.1 Electrodialysis1
A. 1.3.2 Electrochemical ion exchange4
A. 1.3.3 Distillation of boric acid 39
A. 1.3.4 Reverse osmosis 4
A. 1.3.5 Ion exchange3
A. 1.3.6 Conclusions
A.2 Bench-top experiments on genuine waste5
A.2.1 Electrodialysis7
A.2.1.1 Introduction2 Results of tests9
A.2.1.3 Conclusions 63
A.2.2 Electrochemical ion exchange4
A.2.2.1 Introduction and test conditions2 Results6
A.2.3 Distillation of boric acid 67
A.2.3.1 Distillation of trimethyl borate2 Evaporation of boric acid at high temperature and pressure 68
III A.3 Pilot plant experiments 75
A.3.1 Electrodialysis7
A.3.1.1 First test series 82 2 Second test series 90
A.3.1.3 Conclusions1
A.3.2 Electrochemical ion exchange
A.3.2.1 Pilot plant design, construction and operation 92 Active experiment 1
A.3.2.3et 2 .95
A.3.2.4 Summary 105 Conclusions3
A.3.3 Distillation of boric acid4
A.3.3.1 Precommissioning of the pilot installation 108 2 Cold tests with the pilot installation9
A.3.3.3 Active tests 111
A.4 Conclusions 12
B. Part Β Development of EIX and Harwell low level waste 127
B.l System modelling9
B.2 Laboratory work
B. 2.1 Conventional EIX test on genuine liquor 13 0
B.2.2 Continuous EIX tests 131
B.2.3 High surface area 3d EIX operation2
B.3 Pilot operation4
B.3.1 Cell design
B.3.2 Inactive testing
B.3.3 Active operation7
B.3.4 Decommissioning 143
B.4 Electrode manufacture
B.4.1 Objectives
B.4.2 Inexpensive current feeders4
B.4.3 Chloring evolution
B. 4.3.1 Anode materials
B.4.3.2 Electrochemical depolarisation and chlorine suppression 153 Use of cation membranes to prevente evolution6
IV Β. 5 ΕΚ electrode lifetime 157
Β.6 Summary 161
Β. 6.1 Benchtop experiments
B.6.2 Pilot scale operation2
B.6.3 High surface area 3d EDC operation 163
B.6.4 Electrodes4
B.6.5 ELX Lifetime5
B.7 Conclusions
B.7.1 Harwell LLW
B.7.2 Electrodes 166
B.7.3 ELX lifetime
C. Part C Uranium mine tailing wastes7
C.l Introduction9
C.2 Objective 171
C.3 The classic process of flocculation 17
C.4 Reverse osmosis (R.O.) experiments4
C .4.1 Laboratory experiments
C.4.2 Pre-treatments 175
C.4.3 In situ experiments7
C.4.3.1 Tests with the Rochem unit
C.4.3.2 Tests with RO membrane with different cut-off 183
C.5 EIX experiments 186
C.5.1 Precipitative CELX
C.5.2 Bench-top tests at Harwell7
C.5.3p tests at LNETI 192
C.5.3.1 Experiments Β and C3 2s D and E5
C.5.4 Further bench-top tests at Harwell
C.6 Concluding remarks and R.O. and EIX processes9
C.7 Economic aspects 201
C.7.1 Conventional R.O. industrial unit2
C.7.2 R.O. with NF membrane
C.8 Conclusion3
V INTRODUCTION
In the framework of the European radwaste research programme, processes for the
treatment of low level liquid waste have been studied.
The work has been performed by four partners i.e. LABORELEC (B), SCK-CEN (B),
AEA-HARWELL (UK) and LNETI (Portugal) with financial support of the European
Communities under contract F12W-CT90-0057 (DTEE).
The objectives of the programme are :
• elimination of boron from low level liquid waste of PWR-plants. Five
processes have been evaluated (electrodialysis, reverse osmosis, distillation of
boric acid, ion exchange and electrochemical ion exchange).
• demonstration of the capabilities, reliability and cost-effectiveness of these
processes for the treatment of real PWR wastes over realistic time scales and
representative throughputs.
• evaluation of electrochemical ion exchange on wastes from a nuclear research
center in comparison with traditional flocculation/filtration processes ;
development of electrodes and inexpensive current feeders for electrochemical
ion exchange (EDQ.
• evaluate reverse osmosis and electrochemical ion exchange for the removal of
Ra and other heavy metals from uranium mine tailing wastes in comparison
with flocculation.
The present report will be divided in 3 main parts :
Part A separation of boron from PWR-waste
Part Β development of EIX and experiments on wastes from a research center
uranium mine tailing wastes. PartC Definitions
Membrane processes (electrodialysis, reverse osmosis, electrochemical ion exchange and
ultrafiltration) are grandly used in this report.
To qualify the flows entering or generated by the process, we have used the following
definitions :
"Feed effluent" effluent to be treated by the process
"Product" effluent purified
"Concentrate" effluent in which the pollutants are concentrated
Product
Feed effluent
Concentrate