Werner Von Lensa

CARBOWASTE: New EURATOM Project on ‘Treatment and Disposal of Irradiated Graphite and Other Carbonaceous Waste’

A new European Project has been launched in April 2008 under the 7th EURATOM Framework Programme (FP7-211333), with a duration of four years, addressing the ‘Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste (CARBOWASTE)’. The objective of this project is the development of best practices in the retrieval, treatment and disposal of irradiated graphite & carbonaceous waste-like structural material e.g. non-graphitised carbon bricks and fuel coatings (pyrocarbon, silicon carbide). It addresses both legacy waste as well as waste from future generations of graphite-based nuclear fuel. After defining the various targets for an integrated waste management, comprehensive analysis of the key stages from in-reactor storage to final disposal will then be undertaken with regard to the most economic, environmental and sustainable options. This will be supported by a characterisation programme to localize the contamination in the microstructure of the irradiated graphite and so more to better understand their origin and the release mechanisms during treatment and disposal. It has been discovered that a significant part of the contamination (including 14 C) can be removed by thermal, chemical or even microbiological treatment. The feasibility of the associated processes will be experimentally investigated to determine and optimise the decontamination factors. Reuse of the purified material will also be addressed to close the ‘Graphite Cycle’ for future graphite moderated reactors. The disposal behaviour of graphite and carbonaceous wastes and the improvement of suitable waste packages will be another focus of the programme. The CARBOWASTE project is of major importance for the deployment of HTR as each HTR module generates (during a 60 years operational lifetime) about 5,000 to 10,000 metric tonnes of contaminated graphite containing some Peta-Becquerel of radiocarbon. It is strongly recommended to take decommissioning and waste management issues of graphite-moderated reactors already into account when designing new HTR concepts.Copyright

The production of hydrogen by nuclear and solar heat

Both nuclear and solar energy represent significant carbon-free sources, which may contribute robust elements to a cleaner energy economy, to develop domestic energy sources for the purpose of energy security and stability, and to reduce national dependencies on imports of fossil fuels. Hydrogen, on the other hand, represents a fuel which is clean, powerful and an environmentally benign source of energy to the end-user. The current production of hydrogen is mainly based on hydrocarbons as feedstock, e.g. steam reforming of natural gas.

Nuclear Coal Gasification for Hydrogen and Synthetic Fuels Production

The most abundantly available fossil fuel on Earth is coal. For countries like China, the USA, South Africa, or Germany, coal plays a dominant role as energy resource. The introduction of nuclear energy into coal refinement processes would be a significant contribution to the saving of resources, lowering specific carbon emissions and reducing dependencies on oil and natural gas imports. In Germany, comprehensive R&D activities were conducted within the project “Prototype Plant Nuclear Process Heat” (PNP) to investigate the utilization of nuclear energy from a pebble-bed HTGR in both steam-coal gasification and hydro-gasification. A major component to be newly developed was the gas generator. Its operation on semitechnical scale confirmed the feasibility of allothermal, continuous coal gasification under nuclear conditions. A key problem remained the selection of appropriate high temperature materials for gas generator and other high temperature heat exchanging components. The project was accompanied by comprehensive safety studies targeting tritium contamination and consequences of potential explosions of flammable gas mixtures. Future activities could take benefit from a reevaluation of the studies conducted in the past by comparing HTGR process heat applications against current technologies. Fossil fuel market conditions and environmental effects shall be considered. Superior safety features and high reliability are prerequisites for the introduction of nuclear process heat and nuclear combined heat and power.© 2010 ASME