Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

Parameter State-of-the-art need for itER need for DEMO
Flowrate 6 liters/min 120 liters/min 500 liters/min?
time required 24 hr 1 hr 1 hr
tritium inventory 100 gm 4000 gm 6000 gm
Duty cycle 15% 5% 50%
Power
tritium breeding
requirement
designed for 1000
mW power plant
none
500 mW 2000 mW
1.4 kg tritium burned per year
(none bred in original phase)
145
must breed all
tritium
scaleup of the fuel cycle for demo will require new technologies and challenge existing technologies.
This scaleup will underlie much of the fuel cycle needs.
Fuel Cycle approach
considering the fuel cycle in the context of demo (substantial scaleup), the following aspects will
be challenging: 1) fusion fuel processing, 2) vacuum and fueling, 3) containing and handling tritium,
4) performing tritium accountability and nuclear facility operations, 5) breeding tritium, 6)
extracting tritium from the breeding system, and 7) in-vessel tritium characterization, recovery
and handling. each area will be described along with the state-of-the-art and gaps between the
latter and what is needed.
FUSION FUEL PROCESSINg (Need 1)
Description: The fusion fuel cycle is composed of the following sub-systems: fuel cleanup (for
iteR tokamak exhaust Processing), isotope separation, tritium storage and delivery, water detritiation,
tritium pumping, effluent detritiation, gas analysis, and process control.
State-of-the-art: The state-of-the-art for each of these systems was developed at tsta, JaeRi,
Fzk, Jet, sRnl, tFtR, chalk River and other facilities. These systems were typically tested at
1/20th the scale of iteR (or less). iteR will be a major technological challenge and much will be
learned from it. The iteR tritium systems will largely be a production system with little opportunity
for experimentation. demo will require higher throughput (4 x iteR) and a higher duty factor
(10 x iteR)
gaps: due primarily to scaleup, all demo sub-systems will require improvements including: better
technology, tritium inventory minimization, accuracy improvement, increased throughput,
avoidance and/or handling tritiated water, improved duty cycle and design and diagnosis tools.
VACUUM AND FUELINg (NEED 2)
Description: The vacuum and fueling systems are composed of the key sub-systems: torus vacuum
pumps, roughing pumps, gas puffing, pellet fueling, disruption mitigation and elm pacing
(an elm is an edge localized mode – an instabiliy affecting the plasma near the vessel wall). torus
vacuum pumping must maintain low divertor pressure (~10 Pa) while removing helium ash that
will be generated by the fusion burn. The fueling system must provide d-t fuel to the burning