Breeding blanket
The tritium breeding blanket (also known as a fusion blanket, lithium blanket or simply blanket), is a key part of many proposed fusion reactor designs. It serves several purposes; one is to act as a cooling mechanism, absorbing the energy from the neutrons produced within the plasma by the nuclear fusion reaction between deuterium and tritium (D-T), another is to "breed" further tritium fuel, that would otherwise be difficult to obtain in sufficient quantities, through the reaction of neutrons with lithium in the blanket.[1] The breeder blanket further serves as shielding, preventing the high-energy neutrons from escaping to the area outside the reactor and protecting the more radiation-susceptible portions, such as ohmic or superconducting magnets, from damage.
Of these three duties, it is only the breeding portion that cannot be replaced by other means. For instance, a large quantity of water makes an excellent cooling system and neutron shield, as in the case of a conventional nuclear reactor. However, tritium is difficult to obtain in sufficient quantity to run a reactor through other means, so if commercial fusion using the D-T cycle is to be achieved, successful breeding of the tritium in commercial quantities is a requirement.
Breeding blanket designs are mostly based on lithium containing ceramics, with a focus on lithium titanate and lithium orthosilicate.[2] These materials, mostly in a pebble form, are used to produce and extract tritium and helium; must withstand high mechanical and thermal loads; and, should not become excessively radioactive upon completion of their useful service life.
To date, no large-scale breeding system has been attempted, and it is an open question whether such a system is possible to create.
ITER runs a major effort in blanket design and will test a number of potential solutions.[3] Concepts for the breeder blanket include helium-cooled lithium lead (HCLL), helium-cooled pebble bed (HCPB), and water-cooled lithium lead (WCLL) methods.[4] Six different tritium breeding systems, known as Test Blanket Modules (TBM) wil be tested in ITER.[5]
References
- ^ "Tritium" (PDF). FAS/DoD. Retrieved 2021-11-30.
- ^ Lithium breeder ceramics Journal of the European Ceramic Society
- ^ "What is ITER?". ITER. Retrieved 2021-09-14.
- ^ Federici, G.; Boccaccini, L.; Cismondi, F.; Gasparotto, M.; Poitevin, Y.; Ricapito, I. (2019-04-01). "An Overview of the EU breeding blanket design strategy as an integral part of the DEMO design effort". Fusion Engineering and Design. 141. Amsterdam, Netherlands: Elsevier: 30–42. doi:10.1016/j.fusengdes.2019.01.141.
- ^ Giancarli, Luciano (2016-11-07). "Committee Reviews Progress on Test Blanket Modules". ITER Newsline. St. Paul-lez-Durance, France: ITER. Retrieved 2021-03-20.
External links
- "Tritium Breeding". ITER.
- Giancarli, Luciano (5 June 2017). "Tritium breeding systems enter preliminary design phase". ITER.