Meeting the Technology Needs for a Tokamak DEMO: A Strategy Including Mirror Based Nuclear Test Facilities

This study considers an “alternate” approach to obtaining the data base required for building a tokamak demonstration reactor (DEMO). The present generation of physics machines (JET, TFTR, T-15, JT-60) is followed by a larger tokamak physics machine (called a NET-P class device) which achieves ignition and perhaps long pulse operation with a D/T-plasma and a respectable neutron wall loading, but with low duty factor and low neutron fluence. In parallel with this machine is a tandem mirror based technology test device (called TASKA class device), which provides high neutron fluence operation with a much smaller plasma volume and fusion power level. It also provides extended neutron testing of blanket modules, materials test samples, neutral beam and RF heating technology, magnets, tritium handling technology, and other components in an integrated facility. Furthermore, fission reactor facilities and simulation test stands would provide additional data. Even though this study is not all-inclusive, some important conclusions may be drawn. Overall, it appears that the “Alternate Plan” could provide the required physics and most of the engineering data for building a DEMO with less risk, in a shorter time, and with perhaps less cost than the present approach of building a single large tokamak aimed at both physics and engineering testing. This conclusion is valid in an overall sense, but some drawbacks remain. The detailed conclusions with respect to the various physics and technology aspects are given in the paper.