29th Symposium on Fusion Technology (SOFT 2016)

O5A.2 Fusion Reactor Start-up without an External Tritium Source

8 Sep 2016, 17:00

20m

Forum Hall 2nd floor (Prague Congress Centre)

Board: 2

Oral H. Fuel Cycle and Breeding Blankets O5A

Speaker

Shanliang Zheng (CCFE)

Description

Although the D-T reaction is the most promising for fusion and is widely promoted, the amounts of tritium necessary to provide a sustainable fuel supply do not exist naturally. Besides the tritium must be self-sufficient operating a reactor, the initial fuel loading to start up any large-scale D-T fusion reactor remains a significant issue. We have examined the feasibility of starting a reactor from the D-D reactor. There are two likely D-D fusion reaction channels, 1) D+D->T+p, and 2) D+D->He3+n. The tritium can be generated via the reaction channel ‘1)’ and the 2.4MeV neutrons from ‘2)’ react with lithium-6 in the breeding blanket to produce more tritium to be fed back into plasma fuel. Quantitative evaluations are conducted to parametrically assess the feasibility and suitability of this approach to FPP reactors, including the economic impact of operation without net electricity generation. The results suggest that D-D operation may be required for ~1 week to 2 months to accumulate sufficient start-up tritium to launch a tritium seeded D-D dominant plasma operation. The fusion power increases from 9.3MW (~2.53MW from secondary D-T fusion reactions), for pure D-D fusion, to 44MW (~37.5MW from D-T fusion reactions), for the mixed fuel fusion operation with 1% tritium injected into the plasma core. As soon as the operation starts to consume tritium in fusion reactions, the tritium accumulation will be largely dependent to the surplus tritium bred in the breeding blanket. The tritium fractional burn-up is a critical factor determining the length of time taken to accumulate sufficient tritium for 50:50% D-T operation. The time taken to accumulate sufficient tritium for 1 day operation would be more than 2 years for 5% burn-up but reduce to 8 months for 20% burn-up fraction assuming 2.4GW D-T fusion power and TBR of 1.2.