Dear Editor
Re: letter from G M Smith, with the figure from NRPB-R210.
The statement which you made (“despite the fact that fusion produces no high level radioactive waste...”) is correct. Since the NRPB report was written fusion technology has developed considerably, in particular there has been a massive programme of development of low-activation structural steels for fusion, mainly in Europe and Japan. This has resulted in the creation of martensitic steels, which have low activation potential, as well as superior thermo-physical properties. Essentially this has been done by replacing alloying metals having unfavourable activation characteristics, such as nickel and manganese, with other metals in the steel.
In parallel there have been two major programmes called Safety and Environmental Assessment of Fusion Power. The second such programme, which I co-led, is reporting shortly. The following extract from the draft Executive Summary is an accurate statement of the position.
“Management of activated material:
Over their lifetimes, fusion power stations would generate, by component replacement and decommissioning, activated material similar in volume to that of fission reactors, but qualitatively different in that the long-term radiotoxicity is very considerably lower.
After about a hundred years, radiotoxicity indices (relating to ingestion and inhalation) for the total activated materials from all of the plant models falls to levels comparable with the ashes from coal-fired plants.
Virtually all – perhaps all – of the activated material could be cleared from regulatory control or recycled after about fifty years, leaving little, if any, material requiring permanent repository disposal. This holds for the models based on low-activation ferritic-martensitic steel as well as the model based on vanadium alloy. The heat generated by the material does not require active cooling, except possibly for a small fraction of the material during the first few years. Broadly, about 35% of the activated material could be disposed of as waste in shallow geological repositories. The technology of recycling has still to be developed, and its economic attractiveness in the future cannot be assessed.
Thus the activated material from fusion would not constitute a waste management burden for future generations.”
Thus, if the recycling option were taken, there would be almost no repository waste of any description. Even if recycling were not adopted, there would be no high level waste. But it is true to say that near-plasma components might require cooling for a few years.
