A thermo-nuclear fusion experimental reactor produces a large amount of energy that is mainly transported from the plasma by neutrons and deposited in the machine components, generating nuclear activation. One of the elements used in the fusion reaction is tritium, the radioactive isotope of hydrogen, but in many instances, experimental facilities are based on deuterium only reactions and do not use tritium as fuel. High temperatures in the plasma-facing components and in other parts of these facilities require specific cooling systems that are subject to the neutron activation and that transport the radioactivity into their loops and components. Because of the above considerations, the radiation sources in an experimental fusion machine could be: • the primary neutronic field resulting from the fusion reactions occurring in the reaction chamber, • the gamma radiation generated from neutrons’ interaction with the machine components, • the X and gamma radiation due to the plasma currents, • the gamma radiation emitted by activated products in the machine components • loose contamination from activated dust generated in the machine components, • activated corrosion products generated in the cooling loops after the activation of the inner wall of cooling water pipes, • activation of the cooling water, • tritium used as fuel for the fusion reaction or produced in the D-D fusion reactions, • wastes, still containing tritium and gamma emitters, • activated air produced in the main hall atmosphere and released to the environment, • neutrons and secondary gamma radiation generated in Neutral Beam Injectors. The current analysis is a brief review of the studies on the subject, aimed to define the radiation protection approach to be applied to the next fusion experimental machines. Specific reference will be made to the DTT experimental fusion device which is in an advanced design phase in Italy. Activities developed at different experimental fusion machines, like TFTR in the USA, JET in England, JT60 in Japan, together with some minor experiments implemented in Italy, will be the basis for identifying the typical radiological source terms. Finally, the studies performed for designing the international project ITER and the Italian DTT will be considered for providing qualitative and quantitative information about the radiological source terms and the potential radioactive waste produced and released to the environment.
The radiological source terms in a nuclear fusion experimental facility
Sandri S.;Contessa G. M.;Guardati M.;Villari R.
2021-01-01
Abstract
A thermo-nuclear fusion experimental reactor produces a large amount of energy that is mainly transported from the plasma by neutrons and deposited in the machine components, generating nuclear activation. One of the elements used in the fusion reaction is tritium, the radioactive isotope of hydrogen, but in many instances, experimental facilities are based on deuterium only reactions and do not use tritium as fuel. High temperatures in the plasma-facing components and in other parts of these facilities require specific cooling systems that are subject to the neutron activation and that transport the radioactivity into their loops and components. Because of the above considerations, the radiation sources in an experimental fusion machine could be: • the primary neutronic field resulting from the fusion reactions occurring in the reaction chamber, • the gamma radiation generated from neutrons’ interaction with the machine components, • the X and gamma radiation due to the plasma currents, • the gamma radiation emitted by activated products in the machine components • loose contamination from activated dust generated in the machine components, • activated corrosion products generated in the cooling loops after the activation of the inner wall of cooling water pipes, • activation of the cooling water, • tritium used as fuel for the fusion reaction or produced in the D-D fusion reactions, • wastes, still containing tritium and gamma emitters, • activated air produced in the main hall atmosphere and released to the environment, • neutrons and secondary gamma radiation generated in Neutral Beam Injectors. The current analysis is a brief review of the studies on the subject, aimed to define the radiation protection approach to be applied to the next fusion experimental machines. Specific reference will be made to the DTT experimental fusion device which is in an advanced design phase in Italy. Activities developed at different experimental fusion machines, like TFTR in the USA, JET in England, JT60 in Japan, together with some minor experiments implemented in Italy, will be the basis for identifying the typical radiological source terms. Finally, the studies performed for designing the international project ITER and the Italian DTT will be considered for providing qualitative and quantitative information about the radiological source terms and the potential radioactive waste produced and released to the environment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
