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

plasma and gas to the scrape-off layer (sol) and divertor to minimize impurity generation and
sweep impurities to the divertor. Furthermore, systems must be provided for massive gas injection
or other systems for disruption mitigation and rapid small pellets for elm pacing.
State-of-the-art: The pumping system for iteR consists of eight cryosorption pumps that are
regenerated every five minutes in a cyclic fashion. These pumps are backed by tritium compatible
roughing pumps (still under development). Frequent regeneration will be challenging. The pellet
fueling system for iteR will be become the state-of-the art, but the demo requirement will be
more demanding (4 x iteR on flowrate and 10 x on duty cycle). Pellet penetration requirement
may need to be increased (4 x iteR on flowrate and 10 x on duty cycle). The state-of-the-art for
disruption mitigation is gas jets. elm mitigation with pellet pacing is not well developed. The
next few years will hopefully answer the question of whether this could be employed. The requirements
for disruption and elm mitigation in demo are completely unknown at this point. These
requirements could have a significant effect on the fueling and pumping systems as well as the
overall fuel cycle design.
gaps: demo will require improved vacuum systems such as roughing pumps and cryopumps. Pumps
that separate species have advantages. Gaps for the fueling systems are to be determined based on
unknowns for demo such as fueling penetration requirements, feed rate, tokamak/not tokamak,
etc. also, the gaps for demo disruption mitigation and elm pacing are presently to be determined.
CONTAININg AND HANDLINg TRITIUM (NEED 3)
Description: tritium is hazardous to workers, the public and the environment. to mitigate this
hazard it must be properly contained and handled. systems for this consist of: primary, secondary
and tertiary containment; permeation barriers; occupational and environmental monitoring;
maintenance systems; waste handling, characterization processing and disposal; decontamination
and decommissioning; and personnel protection equipment.
State-of-the-art: experience at recent tritium facilities. iteR will be challenged in this area and
demo will be an even greater challenge with high-temperature operation, useful power extraction
and higher duty factor.
gaps: control of tritium through nontraditional tritium-handling equipment (heat exchangers;
large, high-temperature components; long high-temperature pipe runs) will require significant attention.
Room processing systems will be challenging. Permeation barriers would help, but development
has not been successful, and the barrier factor is diminished under irradiation.
PERFORMINg TRITIUM ACCOUNTABILITy AND NUCLEAR FACILITy OPERATIONS (NEED 4)
Description: a facility with significant amounts of tritium must operate with a methodology which
ensures that the facility’s tritium is not a practical threat to workers, the public and the environment,
and that it has not been diverted from the facility. This area consists of 1) tritium accountability
measurement techniques, 2) tritium accountability methodology and procedures, 3) nonproliferation
approaches, 4) systems and approaches to ensure worker and public safety (authorization basis),
5) tritium transportation technology and approaches, 6) waste repository, and 7) tritium supply.
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