DEMO Hot Cell and Ex-Vessel Remote Handling

DEMO Hot Cell and Ex-Vessel Remote Handling

DEMO Hot Cell and Ex-Vessel Remote Handling 150 150 Mathew

DEMO Hot Cell and Ex-Vessel Remote Handling

In Europe the work on the specification and design of a Demonstration Power Plant (DEMO) is being carried out by EFDA in the Power Plant Physics and Technology (PPP&T) programme. DEMO will take fusion from experimental research into showing the potential for commercial power generation. During the fusion reaction, components in the tokamak become highly activated. The estimated dose rate levels after shutdown (zero decay time) due to 60 dpa accumulation in steel (blanket) and 30 dpa (divertor) are 13.1-17.4 kGy/h (blanket); 8.8-11.6 kGy/h (divertor)[1], much higher than those to be encountered at ITER. Upon removal from the tokamak, components would be transported to the Hot Cell facility with attention to minimizing the spread of activated dust and tritium contamination. It is proposed to use a sealed cask of ~20 tonnes, running on air castors with 50% lifting capability redundancy. Due to the number and complexity of the routes taken by this transporter it would have to be an un-tethered semi-autonomous system. This poses some technical challenges, including providing sufficient battery capacity, reliable guidance and a fail safe un-tethered control system. The mass of the components being moved is assumed here to range from a few tonnes to in excess of one hundred tonnes. Before the removed in-vessel components can be processed in the Hot Cell, they would require a period of cooling, approximately 2.5yrs, to allow dose rate and decay heating to reduce. This reduces the decay heating level to ~1-1.5 kW/m³ and a contact dose rate to ~250Sv/hr, which is more suited to dexterous man-in-the-loop Remote Handling (RH). During maintenance, many components would require replacement or refurbishment. The Hot Cell facility would have to provide all the associated RH functions and operate fully remotely. With no human intervention, an accordingly robust RH recovery system would be required. This paper describes the first steps being taken towards the design of the DEMO Hot Cell. It will show a comparison of the current DEMO in-vessel maintenance concepts from a Hot Cell perspective, describe a proposed ex-vessel transport system, and summarize the facilities that have been identified as required within the Hot Cell, examine current RH technology and discuss the identified critical development issues.

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17/10/2013