Abstract
The design of a power plant based on the spherical tokamak (ST) is being developed in order to explore the potential advantages of the ST for power production. The ST power plant operates at a low aspect ratio of typically 1.4-1.6, which allows operation at high beta. This offers stability at high elongation which permits operation at high bootstrap current fraction (> 95%), leaving only a modest external current drive requirement. This high elongation also results in a relatively uniform neutron wall loading giving the first wall components a longer life before replacement is required. The ST can be readily maintained on a timescale commensurate with this material life since its simple and robust centre column can be easily removed by lowering it into a hot cell beneath the load assembly and replaced with a new or reconditioned one. This is possible because it does not require inboard breeder blankets to maintain its tritium economy, or a substantial inboard shield since the centre column consists of a water-cooled copper centre rod surrounded by a relatively thin steel neutron shield. The plasma is operated in a double null configuration, forming both an upper and lower divertor. In order to accommodate the high erosion rates and heat fluxes developed in the divertors a novel system based on the use of a cascading flow of silicon carbide pebbles has been evaluated. The layout of the main elements of the power plant has been developed with revised power flows giving the steam cycle a thermal efficiency of about 43%. Crown
| Original language | English |
|---|---|
| Pages (from-to) | 65-71 |
| Number of pages | 7 |
| Journal | Fusion Engineering and Design |
| Volume | 63-64 |
| DOIs | |
| State | Published - Dec 2002 |
| Externally published | Yes |
Funding
The output power requirement for the TF coil power supply is nominally 32 mA at only about 7.9–8.5 V. This low voltage and high current requires careful consideration of the power supply technology to avoid high power losses within it. Although a number of different technologies have been considered, a transformer–rectifier system has been selected as the baseline option because it requires little development, has no moving parts and has acceptable internal power losses. Previous ST reactor studies [3–5] included a proposal for a 6 mA power supply to feed the single turn TF coil system and was supported by an industrial design study contract. A 32 mA power supply scheme is proposed here based on an extrapolation of that previous design.
| Funders | Funder number |
|---|---|
| H2020 Euratom | |
| Department of Trade and Industry |
Keywords
- Power plant
- Spherical tokamak
- Thermal efficiency
