Institute for Transuranium Elements: annual report 1993

280 Pages·2008·9.12 MB·English

by  European Commission

ISSN 1018-5593
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A N N U A L - R E P O RT
European Commission
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EUROPEAN COMMISSION
Report
EUR 15741 EN

COMMISSION OF THE EUROPEAN COMMUNITIES
Joint Research Centre
INSTITUTE
FOR TRANSURANIUM ELEMENTS
KARLSRUHE
Annual Report 1993
TUAR-93
EARL. rUROP. Biblioth.
fj EUR 15741 EN
1994
_J
Published by the
EUROPEAN COMMISSION
Directorate-General XIII
Telecommunications, Information Market and Exploitation of Research
L-2920 Luxembourg
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
Reproduction is authorized, except for commercial purposes,
provided the source is acknowledged
This report was compiled and edited by H. E. Schmidt, J. Richter, and L. Ruczka
Inquiries for more details should be addressed to the Programme Office,
Institute for Transuranium Elements, P. O. Box 2340, D-76125 Karlsruhe,
Phone [phone], FAX [phone]
For further information concerning JRC programmes please contact the
Directorate General Science, Research and Development of the
European Commission, 200 rue de la Loi, B-1049 Brussels, Belgium
Luxembourg: Office for Official Publications of the European Communities, 1994
ISBN 92-826-4367-0
© ECSC-EC-EAEC, Brussels • Luxembourg, 1994
Printed in Germany
Abstract
Basic Safety Research with Nuclear Fuels concentrated in 1993 on studies of high burn­up
U0 in order to elucidate mechanisms leading to changes in structure and composition at the outer
2
surface of the fuel pellets (RIM effect). The structural changes (polygonisation) observed after
extended irradiation could be reproduced in simulation experiments by high dose ion implantation
with fission products. For the first time, the oxygen potential in the rim region of high burn­up fuel
could be determined. ­ In a theoretical study, heat exchange mechanisms operative in uranium
dioxide at elevated temperatures were identified and possible contributions (lattice vibrational
and electronic) to the specific heat of U0 were further analysed. ­ After conclusion of Knudsen cell
2
effusion measurements with simulated fuel (SIMfuel), a specimen of irradiated U0 was
2
introduced into the installation and a first series of vapour pressure measurements with genuine
high burn­up fuel was successfully performed. The equipment is now ready to be used for high
burn­up fuel analyses and source term studies. ­ New program options became available for the
TRANSURANUS fuel pin code which is more and more being used by external partners from
science, industry, and licensing authorities.
Safety Aspects of Fuel Operation and Handling were dominant in the design and execution of
the POMPEI high burn­up irradiation experiment under execution in the Petten High Flux
Reactor. Besides equipment for studying the long­term irradiation behaviour of mixed nitrides,
the POMPEI device contains technetium samples for transmutation studies. ­ Slightly radioactive
aerosols (U0 ) were introduced into the installation to study the mechanisms governing the
2
transport of big particles in ducts under turbulent flow conditions.
Actinide Determination and Recycling concentrated on partitioning and transmutation
studies: The results of the first series of fast flux minor actinide oxide irradiations (SUPERFACT I)
were analysed, possible P&T schemes were reviewed and two methods for actinide partitioning
from highly active waste, based on TRPO and on CMPO.were tested with real HAW and in there
performance compared.
Electrochemical techniques were extensively used to investigate UO, corrosion in aqueous
solution in the context of studies on the Characterisation of Waste Forms and of High Burn­
Up Fuel. Leaching studies under highly oxidizing conditions were performed with LWR fuel, and
the comparison of leach rates of U0 and glass in the presence of granite was continued. In order to
2
clarify the chemistry at the fuel periphery, the properties of cesium uranate compounds were
studied and material from the cladding/fuel interface was analysed by ICP­mass spectrometry.
Preparative work for Basic Actinide Research concentrated on magnetic compounds of the
ThMn structure type and on actinide containing compounds with compositions 1:1:3, 1:1:1, and
12
2:2:1. A theory of the optical properties of thorium, protactinium, and uranium was developed.
Magnetic moments, exchange interactions and ordering temperatures of gadolinium and curium
under pressure were calculated. Single crystals of NpAs were subject to resonant magnetic X­ray
scattering experiments. Mossbauer investigations with neptunium compounds were continued,
muon spin rotation studies were performed with uranium compounds with the AuCu structure.
3
The electrical resistance of PuSb and the optical response of NpSb and PuSb were investigated
under pressure, and a new high­pressure X­ray diffraction study of americium was undertaken.
Under Exploratory Research, the frequency dependence of acoustic aerosol agglomeration was
investigated in detail.
The majority of the Institute's Scientific­Technical Support to Community Policies concerned
work for the safeguarding of fissile materials: Preparations for the installation and operation of
on­site analytical laboratories in Sellafield and La Hague were continued, and new analytical
techniques ­ ICP­MS in combination with laser ablation and glow discharge mass spectrometry,
and the determination of 23«Pu/239Pu ratios via total evaporation mass spectrometry ­ were
perfected.
Institute for Transuranium Elements ■ Annual Report 1993. EUR 15741 EN
Contract Work was pursued along several lines: The radiotherapeutical study involving 213Bi and
22sAc was extended to the interaction of these nuclides with human cells.The preparation and
characterisation of MA-containing alloys for transmutation studies was continued. Fission product
release studies and pre-test fuel characterisation were performed for the PHEBUS PF project. Fuel
discs with various characteristics were fabricated and sent to Halden for an irradiation experiment
aimed to clarify mechanisms and consequences of the RIM effect.
Institute for Transuranium Elements • Annual Report 1993. EUR 15741 EN
Commission of the European Communities
Joint Research Centre
TUAR 93
European Institute
for Transuranium Elements
Annual Report
January - December 1993

Table of Contents
Foreword 11
Executive Summary 13
MAIN ACHIEVEMENTS AND MILESTONES
1. Specific Programmes 19
1.1 Basic Safety Research on Nuclear Fuels 19
Introduction 19
Structural investigations and basic studies on fuels 19
Work on the RIM-effect 19
Thermal conductivity of simulated high burn-up UO2 fuel 30
Studies on the behaviour of cesium in UO2 35
Effects of exposure to water on the fine-grained rim region
of high burn-up LWR fuel 37
Studies of problems related to reactor safety 40
Ultrasonic thermometers for the PHEBUS project 40
Source term studies 40
Studies of high-temperature properties 46
Introduction 46
Thermodynamics of UO2 47
Autoclave melting experiments 54
Thermophysical property measurements 56
Modelling work 59
Fuel performance code development (TRANSURANUS) 59
Specific model development 60
1.2 Safety Aspects of Fuel Operation and Handling 63
Introduction 63
Optimisation of fuels 63
Institute for Transuranium Elements ■ Annua] Report 1993, EUR 15741 EN
Irradiation experiments 63
Aerosol research 64
Duct transport of big particles 64
1.3 Actinide Determination and Recycling 67
Introduction 67
Status of the SUPERFACT irradiation experiment 67
Introduction 67
Experimental 67
Theoretical 67
Results and discussion 68
Present status of partitioning and transmutation 70
Comparison of possible partitioning and transmutation
schemes when added to the existing nuclear fuel cycle 70
Working Group meeting on MA-containing targets and fuels 75
Partitioning studies with various extractants 75
Introduction 75
Actinide partitioning from genuine HAW by TRPO in a
continuous process 76
Actinide partitioning from genuine HAW in a continuous
CMPO process 79
Conclusions 80
Means and materials for the preparation of transmutation
targets 81
Introduction 81
Target fabrication by the sol-gel process 82
Waste considerations 82
1.4 Characterisation of Waste Forms and of High Burn-up Fuel 85
Introduction 85
Study of natural UO2 in aqueous solution by electrochemical
techniques 87
Electrochemical impedance; evaluation of the
measuring system 87
Electrochemical measurements 89
Institute for Transuranium Elements ■ Annual Report 1993, EUR 15741 EN