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To support the drafting, development, implementation and monitoring of European energy and transport policy, the Institute for Energy and Transport of the European Commissions’ Joint Research Centre conducts pre-competitive research in the areas of experimental qualification of advanced fuels and materials as well as simulation and modelling of reactor safety and material performance. The work covers assessments, design optimisation and improvements to the safety and performance of new, innovative reactor systems, materials and instrumentation, in order to meet the EU's long-term energy needs while respecting enhanced safety, sustainability, and economic aspects. The research is linked, and contributes, to related EURATOM Framework Programme projects, Generation IV International Forum (GIF), International Atomic Energy Agency as well as OECD's Nuclear Energy Agency (OECD NEA) activities. The current paper gives an overview and examples of past, current, and upcoming activities in the areas of reactor safety assessments, advanced fuel irradiation and materials research.

A novel integral approach was applied for the nuclear design analyses performed for the European DEMO Conceptual Study including, for the first time, the automatic generation of analysis models for Monte Carlo calculations from available CAD geometry data by the new McCad conversion tool. Starting from neutronics pre-analyses to define the radial reactor build, a generic neutronics CAD model of the DEMO reactor was constructed serving as basis for the generation of DEMO reactor models employing the HCLL (Helium Cooled Lithium Lead) and HCPB (Helium Cooled Pebble Bed) blankets for the tritium breeding and the power production. The HCLL and HCPB DEMO reactor models were converted to the MCNP geometry representation by the newly developed McCad software tool. The nuclear analyses performed on the basis of MCNP Monte Carlo calculations using the converted models showed that both DEMO reactor variants could satisfy the requirements for a sufficient shielding and tritium breeding performance. As a major outcome of this work it is concluded that the newly established integral approach for neutronics analyses, including the automatic generation of analysis geometry models by McCad, is mature for applications to reactor design analyses and studies.

The paper reports the latest achievements in the neutronics modelling of the electron cyclotron resonance heating (ECRH) launcher installed in the ITER upper port. The computational neutronics analyses have been performed for the extended performance (EP) front steering launcher design, which is accepted by the ITER project as reference. The aim of the paper is to show that the considered launcher design satisfies to the nuclear criteria specified for ITER machine. Results of calculations for the essential nuclear responses such as the neutron fluxes, neutron damages, helium production, and nuclear heating are discussed. The methodology used is focused on Monte Carlo variance reduction techniques for deep-penetration neutron radiation calculations in a very heterogeneous geometry. The Monte Carlo N-particle (MCNP) code was used for the radiation transport calculations with a 3D geometry model of the launcher in ITER machine. The complexity of the launcher geometry makes inevitable to use an automated interface programme McCad for the direct conversion from CAD to MCNP. The results obtained are in compliance with the ITER nuclear regulations. The analyses reveal the necessity of detailed consideration of the most critical launcher components.

This paper describes the application of the interface program McCad to a CAD model of ITER for the automatic generation of a neutronics geometry model for the Monte Carlo particle transport program MCNP. The validity of the generated geometry model was shown by comparing the results of stochastic MCNP volume calculations and the volumes provided by the CAD kernel of the interface program as well as by a neutron wall loading distribution calculation.

This paper is devoted to the radiation shield analyses for the front steering (FS) design of the electron cyclotron resonance heating (ECRH) launcher installed in the ITER upper port. The neutron fluxes, nuclear heat density, helium production, and neutron displacements rate have been calculated by Monte Carlo N-Particle (MCNP) transport code. Three-dimensional MCNP models of the FS ECRH launcher have been produced with high accuracy directly from the CAD geometry models by means of the McCad interface programme. A shielding analysis has been performed to estimate the material composition and optimum length required for the launcher's internal shield. Neutron streaming calculations have been done using the MCNP point detectors method. Variance reductions in nuclear responses of particles track-length estimations were achieved by the optimized weight windows, particles splitting, and Russian roulette techniques. Nuclear design parameters of the FS ECRH launcher have been evaluated by the neutronics analyses with dedicated computational procedures. The analyses show that safety issues and radiation shielding requirements in the FS design are fully satisfied to radiation design limits specified for ITER project.

The paper describes the automatic generation of a JET 3D neutronics model from data of computer aided design (CAD) system for Monte Carlo (MC) calculations. The applied method converts suitable CAD data into a representation appropriate for MC codes. The converted geometry is fully equivalent to the CAD geometry.

This paper is devoted to the neutronics analysis of the electron cyclotron wave (ECW) launching system installed in the ITER upper port. The launcher design developed by FOM Rijnhuizen with a twisted arrangement of straight waveguides was selected to facilitate the maintenance of the ECW system by avoiding mitre bends. Two types of ECW launcher designs were considered in this paper: limited and full focusing. Three dimensional MCNP models of the ECW launchers were developed with high accuracy directly from the CAD geometry models by means of an interface programme. A shielding analysis was performed to estimate the length and thickness required for the shield around the waveguides. A two-step method making use of surface sources and point detectors was applied in the neutron streaming calculations in order to estimate the radiation load on the CVD diamond window. The neutron and gamma fluxes, the nuclear heat density, and the helium production were calculated. The results show that the design limits both for the limited and the full focusing ECW models are met.

Activation characteristics have been assessed for a helium cooled solid breeder blanket on the basis of three-dimensional activation calculations for a 2200 MW fusion power demonstration reactor. FISPACT inventory calculations were performed for the beryllium neutron multiplier, the Li4SiO4 breeder ceramics and the Eurofer low activation steel. Neutron flux spectra distributions were provided by a previous MCNP calculation. Detailed spatial distributions have been obtained for the nuclide inventories and related quantities such as activity, decay heat and contact dose rate. These data are available form the authors upon request. On the basis of the calculated contact gamma dose rates, the waste quality was assessed with regard to a possible re-use of the activated materials following the remote or the hands-on handling recycling options.

The helium cooled pebble bed (HCPB) blanket is one of the two European DEMO blanket concepts proposed for testing in international thermonuclear experimental reactor (ITER). The purpose of the tests is to validate the design principles and the operational feasibility for the demonstration blanket system. This includes the basic support functions like tritium extraction, helium cooling and heat transport, and helium purification. In addition, the basic properties and operating characteristics of the system's materials will be validated. Safety, reliability, maintenance and dismantling will be equally addressed. To assess these qualities, the ITER horizontal ports will be used to provide a relevant fusion plasma and the appropriate nuclear environment. At conclusion of the ITER feat EDA phase (July 2001), a revised design of the HCPB test blanket system have been completed to adapt the previous design (for ITER FDR) to the new operational conditions of ITER and to a new strategy for the blanket testing in this reactor. Design description, performance and safety analyses are presented in this paper.

The novel Monte Carlo technique for calculating point detector sensitivities has been applied to two representative beryllium transmission experiments with the objective to investigate the sensitivity of important responses such as the neutron multiplication and to assess the related uncertainties due to the underlying cross-section data uncertainties. As an important result, it has been revealed that the neutron multiplication power of beryllium can be predicted with good accuracy using state-of-the-art nuclear data evaluations. Severe discrepancies do exist for the spectral neutron flux distribution that would transmit into significant uncertainties of the calculated neutron spectra and of the nuclear blanket performance in blanket design calculations. With regard to this, it is suggested to re-analyse the secondary energy and angle distribution data of beryllium by means of Monte Carlo based sensitivity and uncertainty calculations. Related code development work is underway.

The program McCad provides a CAD interface for the Monte Carlo transport code MCNP. It is able to convert CAD data into MCNP input geometry description and provides GUI components for modeling, visualization, and data exchange. It performs sequences of tests on CAD data to check its validity and neutronics appropriateness including completion of the final MCNP model by void geometries. McCad has been used to convert a 40° ITER torus sector CAD model to a suitable MCNP geometry model. Results of MCNP calculations performed to validate the converted geometry are presented.

In the framework of the European Activation File (EAF) task of the European Fusion Technology Programme, the EAF data relevant to the steel types F82H-mod and MANET-2 were benchmarked experimentally. Samples were activated in an intense neutron field produced in a thick beryllium target by a 19-MeV deuteron beam of the Karlsruhe Isochron-Zyklotron. The irradiated samples were investigated by γ spectrometry. The results were compared with calculations using the FISPACT code, the EAF-4.1 library and the source neutron spectrum as measured by activation foil dosimetry. Calculation-over-experiment ratios between 0.96 and 1.19 are found for the more important medium-halflife radionuclides produced in F82H-mod. Similar values are found for MANET-2.

The International Thermonuclear Experimental Reactor (ITER) will use an electron cyclotron resonance heating (ECRH) system in the upper port of the device for plasma stabilization, heating, and cur...

An extensive benchmark exercise has been conducted on ITER with the objective to test and validate different approaches for the use of CAD generated geometry data for Monte Carlo transport calculations with the MCNP code. The exercise encompassed the generation of a dedicated neutronics CATIA model based on available engineering CAD design data, the conversion into MCNP geometry, the verification of the converted models, and a number of calculations to compare the different approaches with regard to the performance and the validity of the results obtained. The paper briefly reviews the different approaches and provides a detailed description of the ITER benchmark effort, its results and conclusions showing that the approaches have reached the maturity level to allow their application to real ITER design analyses. This is considered an essential step forward for neutronics analysis tools to satisfy ITER quality assurance rules.