BELGIAN NUCLEAR RESEARCH CENTRE MOL BELGIUM 30-49 SCK-CEN's core competence is nuclear research using complex infrastructures. The year 1997 saw the restart of our BR2 materials testing reac- tor after refurbishment (cover photograph) and the onset of the excavation of the second shaft to our underground research facility in clay. T"t ™ Y HE BELGIAN NUCLEAR RESEARCH CENTRE (SCK« CEN) is an institute y of public utility under the tutorship of the Belgian minister in JL charge of energy. About 600 highly qualified researchers and technicians realize an annual turnover of three billion Belgian francs, 50% being covered by a governmental subsidy and 50% by contract work and services for the Belgian and foreign industry and for the European Union. The primary mission of SCK>CEN is research and development in the fields of the safety of nuclear installations, the safe handling and disposal of radioactive waste, and radiation protection and safeguards. It is converted in concrete projects, based on the current priorities of the Belgian authorities and of our customers. The main current projects are, in the field of nuclear safety, • the behaviour of high-burnup and MOX fuel, mostly in collaboration with Belgonucleaire; • the embrittlement of reactor pressure vessels; • the irradiation-assisted stress corrosion cracking of reactor internals; • the irradiation effects on materials for fusion reactors; in the field of radioactive waste research, • the disposal in geological clay formations of high-level radioactive waste and of spent fuel; • the decommissioning of nuclear installations, in particular of the pressurized-water reactor BR3; • the study of alternative waste-processing techniques, such as transmutation; in the field of radiation protection and safeguards, • site and environmental restoration; • emergency planning and response; • scientific support to the programmes of the International Atomic Energy Agency (IAEA), of the Nuclear Energy Agency of the Organiza- tion of Economic Co-ordination and Development (NEA/OECD), and of the European Union. Proper infrastructure is an important condition for the success of our scientific and technical projects. For our international programmes, the most important installations are the VENUS and BR2 reactors, and the underground research facility HADES. The VENUS zero-power critical facility allows the detailed analysis of core configurations, including MOX fuel, and is used intensively by international programmes on reactor core code validation and on reactor pressure vessel dosimetry. The BR2 reactor is a high-flux research reactor with thermal fluxes up to 1015 and fast fluxes up to 7 x lO^n-cm"2^"1. It is used for tests on structural materials and fuel in normal and accidental conditions for all types of reactors and for the fusion programme, and for the production of radioisotopes and the doping of silicon. After Board of Directors Scientific Co-ord. Frank Deconinck Frans Moons Contract Mgmt Ludo Veuchelen General Manager Quality Assurance Paul Govaerts Peter Vermaercke General Secretary Operational Safety Robert De Cock Pascal Deboodt Medical Services Luc Holmstock Radioactive Waste Reactor Safety & BR2 Operation & Cleanup Radiation Protect. Guy Collard Pierre D'hondt Pol Gubel :. "Bernard Ne&rdael ><i>< nfttimid: Aft: AbderraHim,; Technical Services Personnel, Marketing & ; Site;: ; ReacWr ;MateHa1s; -'"T]'^ Finances & Admin. Public Relations Jan Van der Auwera Christian Legrain Jef Vanwildemeersch : Nuclear;Chemistry; ; Reactor Experiments Leon XtarideVeide'.'•"•••. ; Radiatipriip : : replaced'ibyEr Roland Carchon "• Mark 166s ••' Scientific Advisory Committee Yvan Bruynseraede, chairman Michel Giot, vice-chairman Paul Dejonghe Frank Deconinck, chairman of the board Paul Govaerts, general manager Frans Moons, scientific co-ordinator Chairmen of the DACs ;;; Departmental; Advisory Committees;(DACs) \ Waste Reactors Radiation Protect. £ Vansant, chairman £ Mund, chairman C. Huyskens, chairm. J.De Schutter B. De Boeck F. Luykx L. Van den Noortgate C. Vandenberg A. Cremers J-Fuger W. D'Haeseleer P. Smeesters A Hermanne W. Bogaerts A. Janssens R. Jadot H. Van Dam A. Wambersie P. De Prefer D. Haas A. Piron iv an intensive refurbishment programme, the reactor was restarted in April 1997 and is again at the disposal of international programmes for several years. The underground research facility HADES, built in a deep clay layer 225 metres below our site, allows the study of the behaviour of clay, of waste containers, and of the migration of radionuclides in realistic conditions. In co-operation with the Belgian Waste Management company NIRAS/ONDRAF, an important extension of this laboratory is today under construction (the PRACLAY project), to demonstrate the feasibility of the disposal of heat-generating waste. A study has been started with regard to the future construction of an accelerator-driven system, as a multipurpose neutron source for technological and medical applications, including research on transmutation of high-level radioactive waste (the MYRRHA project). The current organization of SCK-CEN is tuned to the end users, with two major scientific divisions: • radioactive waste and cleanup, grouping the departments of waste and disposal, site restoration, nuclear chemistry, and safeguards; • reactor safety and radiation protection, grouping the departments of nuclear fuel, reactor materials, reactor experiments, and radiation protection. The operation of the BR2 reactor, marketing, finances and administra- tion, and general technical support are organized by specific divisions. Common support and control services such as scientific co-ordination, contract management, quality assurance, operational safety, and medical services are joined directly to the general management. An external scientific advisory structure composed of experts in SCK-CEN's field of activities assists the board of directors, the general management, and the heads of divisions and departments. Its members are selected by the board of directors among the academic world and among senior actors of the nuclear community. The scientific advisory structure is based on three departmental committees on radioactive waste, reactors, and radiation protection, overseen by a general scientific advisory committee. The latter can invite international experts to discuss specific topics. This scientific report is structured according to specific activities in the above-mentioned scientific divisions and around BR2. Each chapter groups several related projects. Some cross-divisional activities are grouped under "Exploratory R&D." Each chapter indicates the general context and current achievements, the partners, and the scientific output. At the end of the report, indexes allow to search for individual partners and contributors. NEXT PAGE(S) left BLANK Abbreviations Radiation Protection Health-physics measurements 2 Radiological assessment and optimization 12 Radioecology 17 Environmental restoration 24 Health effects 26 Policy support on radiation protection 33 Reactor Safety Nuclear fuel 36 Reactor physics 41 Reactor safety analysis 46 Reactor structural materials 48 Radioactive Waste and Cleanup Waste management 60 Decommissioning of the BR3 PWR 69 Waste disposal 72 Safeguards 88 Radiochemistry 90 BR2 Operation Refurbishment of BR2 (Phases 4 and 5) 94 Exploratory R&D Fuzzy logic and intelligent technologies in nuclear science 100 Myrrha: a prototype accelerator-driven system 104 Improvement of in-pile instrumentation in experimental devices 106 Advanced instrumentation and teleoperation 107 Jesses 111 The following list explains the main abbreviations used in this report, such as SCK«CEN project names and common acronyms. By contrast, abbreviated names of organizations are explained in the index of partners, sponsors, and customers starting on page 118. ABV Automatic Block Valves ADONIS Accelerator-Driven Operated New Irradiation System AES Auger Electron Spectroscopy ALARA As Low As Reasonably Achievable ARIANE Actinide and fission product Research In A Nuclear Element BACCHANAL Burnup Accumulation for High-performing fuel ANALysis BACCHUS BACkfilling Control for High-level waste Underground Storage BIOMASS Biosphere Modelling and Assessment methods BIOMOVS Biosphere MOdel Validation Study BRl Belgian Reactor 1 BR2 Belgian Reactor 2 BR3 Belgian Reactor 3 BWR Boiling-Water Reactor CALLISTO CApabiLity for light-water Irradiation in Steady-state and Transient Operation CARE Common Approach with regard to REstoration CERBERUS Control Experiment with Radiation for the BElgian Repository for Underground Storage CHIVAS CALLISTO Hot Irradiation of Vessel Alloy Steels CORiOLis COrrosion Related Irradiation Off-line for IASCC Susceptibility COSAC Contaminant Operation SAfety Capsule CRP Copper-Rich Precipitates CVN Charpy V Notch DBTT Ductile-Brittle Transition Temperature DESTIN DEStructive Testing IN-pile loop DNA DeoxyriboNucleic Acid DOLMEN Device for On-Line MEasurement of Neutron flux D&D Decommissioning and Decontamination ECLIPS Experimental Corrosion Loop for In-Pile Studies EDTA EthyleneDiamineTetraAcetate EIG Economic Interest Group EPMA Electron Probe MicroAnalysis FL Fuzzy Logic FLC Fuzzy Logic Control FLINS Fuzzy Logic and Intelligent technologies in Nuclear Science HADES High-Activity Disposal Experimental Site HLW High-Level Waste IASCC Irradiation-Assisted Stress Corrosion Cracking ITER International Thermonuclear Experimental Reactor IVK Igarashi-Vitek-Kantha VIII LFC Loss-Free Counting LHMA Laboratory for