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

State-of-the-art: accountability measurements are performed by in-bed calorimeters or offline
P-v-t methods. Processing times are long and accuracies are limited. accountability methods
rely on periodic reconciliation between “book” inventory and “physical” inventory. Proliferation/diversion
is dictated by an “attractiveness level” as defined in the Us by doe orders (tritium
is considered less attractive than special nuclear materials, but still requires safeguards such as
“Gates, Guards, and Guns” with access restrictions). The authorization basis is defined in the Us
by doe, nRc, Fusion safety code and iteR requirements. Risk-based assessments are used for
calculating dose to the public. “agreements” are made between contractors and doe for chronic
emission limits from facilities. Waste facilities are covered in the safety section.
gaps: Presently under consideration for the iteR torus are tritium accountability measurements
based on “inventory-by-difference” and unavoidable errors predicted to propagate quickly. direct
methods of estimating tritium inventory need to be developed. With increased potential hazard,
demo will require improved accountability methods. The demo authorization basis will require
balancing cost and safety. an important strategy will be demonstrating methodology effectiveness.
tritium waste disposal must be addressed early to ensure that facilities can effectively operate
and shutdown. integration with safety will be important.
BREEDINg TRITIUM (NEED 5)
Description: to date, fusion operations requiring tritium have had tritium supplied from nonfusion
sources (around 20 kg total available). For success, however, demo will have to breed essentially
all of its required tritium. tritium breeding can be broken down in the following areas: 1)
blanket materials and configurations, 2) blanket structural materials, 3) blanket operations and
control, 4) blanket maintenance and disposal and 5) blanket diagnostics.
State-of-the-art: a number of solid and liquid breeder concepts exist. currently the primary development
of both liquid and solid concepts is in the eU and Japan.
gaps: no tritium breeding proof-of-principle has been performed, although any major tritiumusing
facility other than iteR will have to breed its own tritium.
EXTRACTINg TRITIUM FROM THE BREEDINg SySTEM (NEED 6)
Description: to be useful, bred tritium must be extracted from the breeding material. less soluble
materials make it easier to extract the tritium but may suffer from containment issues and
vice versa. it is envisioned that solid breeders will have tritium extracted from the breeder materials
by sweeping helium through the breeder. limited fundamental experiments have been performed.
liquid breeders will flow the breeder and the tritium away from the torus, and a processing
vessel will extract the tritium. some experiments of the latter type have been performed.
State-of-the-art: data-to-date suggest that tritium recovery from the breeding material with
acceptable tritium inventory is feasible, but this has not been performed in an integrated fashion
with tritium containment. only preliminary tests have been performed.
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