Avec les multiples projets de conquête martienne et pour explorer les confins du système solaire ... more Avec les multiples projets de conquête martienne et pour explorer les confins du système solaire et au-delà, la propulsion nucléaire fait un retour en force. Elle ouvre un large champ d’applications, notamment pour raccourcir les durées des « voyages ». Un sujet présenté à l’occasion d’une journée organisée par le CNES, le CEA et la SFEN, à Paris le 24 janvier 2020.
Studies of 20 kWe space nuclear power systems are discussed. In addition to the fast-spectrum, li... more Studies of 20 kWe space nuclear power systems are discussed. In addition to the fast-spectrum, liquid-metal-cooled reactor presently considered as a reference, shorter term gas- and Na(K)-cooled thermal spectrum reactors are being investigated. The need for adequate ZrH moderator temperature conditions is satisfied through a Brayton cycle conversion subsystem featuring two separate, high-temperature heat pipes and low-temperature pumped loop radiators.
La conception et les problemes technologiques rencontres lors de la conception sont analyses pour... more La conception et les problemes technologiques rencontres lors de la conception sont analyses pour les quatre options d'enceinte de recyclage, retenues pour les recherches europeennes: utilisation de ceramique comme materiau regenerateur, de beryllium comme multiplicateur de neutron et d'helium comme fluide de refroidissement
This paper concerns the preliminary investigation of the thermal behaviour and of the afterheat r... more This paper concerns the preliminary investigation of the thermal behaviour and of the afterheat removal capability of the water-cooled lithium-lead box-shaped DEMO blanket in case of Loss-Of-Coolant Accident (LOCA). The thermal behaviour of the outboard-segment first wall and breeder region has been determined in an hypothetical accidental situation where convection cooling of the outboard blanket is totally lost. The case of two separate water-cooling circuits has been considered, and three possible connection schemes have been analyzed. The minimum temperature increase has been obtained when a crossed inboard/outboard cooling-circuits connection is assumed (inboard segment-box and outboard breeder-box from one side, the reverse from the other side). In case of LOCA in the outboard breeder region, the obtained maximum temperature is 550°C reached after about 20 seconds. The corresponding thermal stresses remain below the allowed limit. On the contrary, if the LOCA happens in the outboard segment-box, the maximum temperature of 625°C is reached after 1 hour in the first wall and the thermal stresses are too high. Possible solutions are briefly discussed. A similar analysis has also been performed for a different water-cooled lithium-lead blanket concept, the cylindrical module concept. The comparison between the two concepts indicates that their thermal behaviour in case of LOCA is very similar, although the cylindrical modules concept reaches slightly higher temperatures.
... 1424. [10 ] M. Dalle Donne et al., Conceptual design of a helium-cooled solid breeder blanket... more ... 1424. [10 ] M. Dalle Donne et al., Conceptual design of a helium-cooled solid breeder blanket based on the use of a mixed bed of beryllium and LiaSiO 4 pebbles, Proceedings SOF'I'-17, Rome, 1992 (Elsevier, Amsterdam, 1993) pp. 1326. ... [14 ] H. Feuerstein et al., Behaviour of ...
The potential sources of tritium contamination of the helium-coolant of ceramic breeder blankets ... more The potential sources of tritium contamination of the helium-coolant of ceramic breeder blankets have been evaluated in a previous paper for the specific case of the European BIT DEMO blanket. This evaluation associated with a rough assessment of the permeability to tritium of the tubing of helium-heated steam generators confirmed that the control of tritium losses to the steam circuit is a critical issue for this class of blanket requiring developments in three areas: (1) permeation barriers, (2) tritium recovery processes maintaining a very low concentration in tritiated species in the coolant, and (3) methods for controlling the chemistry of the coolant. Consequently, in order to define the specifications of these developments, a detailed evaluation of the permeability to tritium of helium-heated steam generators (SGs) was performed, which will be reported in this paper. This study includes the definition of the thermal-hydraulic operating conditions of the SGs through thermodynamic cycle calculations, and its thermal-hydraulic design. The obtained geometry, area and temperature profiles along the tubes are then used to estimate, based on relevant permeability data, the tritium permeation through the SG as a function of the composition in tritiated species of the coolant. The implications of these results, in termsmore » of requirements for the considered tritium control methods, will also be discussed on the basis of expected limits in tritium release to the steam circuit.« less
In the frame of the recent CEA studies aiming at - the development, evaluation and comparison of ... more In the frame of the recent CEA studies aiming at - the development, evaluation and comparison of solid breeder blanket concepts in view of their adaptation to NET
Avec les multiples projets de conquête martienne et pour explorer les confins du système solaire ... more Avec les multiples projets de conquête martienne et pour explorer les confins du système solaire et au-delà, la propulsion nucléaire fait un retour en force. Elle ouvre un large champ d’applications, notamment pour raccourcir les durées des « voyages ». Un sujet présenté à l’occasion d’une journée organisée par le CNES, le CEA et la SFEN, à Paris le 24 janvier 2020.
Studies of 20 kWe space nuclear power systems are discussed. In addition to the fast-spectrum, li... more Studies of 20 kWe space nuclear power systems are discussed. In addition to the fast-spectrum, liquid-metal-cooled reactor presently considered as a reference, shorter term gas- and Na(K)-cooled thermal spectrum reactors are being investigated. The need for adequate ZrH moderator temperature conditions is satisfied through a Brayton cycle conversion subsystem featuring two separate, high-temperature heat pipes and low-temperature pumped loop radiators.
La conception et les problemes technologiques rencontres lors de la conception sont analyses pour... more La conception et les problemes technologiques rencontres lors de la conception sont analyses pour les quatre options d'enceinte de recyclage, retenues pour les recherches europeennes: utilisation de ceramique comme materiau regenerateur, de beryllium comme multiplicateur de neutron et d'helium comme fluide de refroidissement
This paper concerns the preliminary investigation of the thermal behaviour and of the afterheat r... more This paper concerns the preliminary investigation of the thermal behaviour and of the afterheat removal capability of the water-cooled lithium-lead box-shaped DEMO blanket in case of Loss-Of-Coolant Accident (LOCA). The thermal behaviour of the outboard-segment first wall and breeder region has been determined in an hypothetical accidental situation where convection cooling of the outboard blanket is totally lost. The case of two separate water-cooling circuits has been considered, and three possible connection schemes have been analyzed. The minimum temperature increase has been obtained when a crossed inboard/outboard cooling-circuits connection is assumed (inboard segment-box and outboard breeder-box from one side, the reverse from the other side). In case of LOCA in the outboard breeder region, the obtained maximum temperature is 550°C reached after about 20 seconds. The corresponding thermal stresses remain below the allowed limit. On the contrary, if the LOCA happens in the outboard segment-box, the maximum temperature of 625°C is reached after 1 hour in the first wall and the thermal stresses are too high. Possible solutions are briefly discussed. A similar analysis has also been performed for a different water-cooled lithium-lead blanket concept, the cylindrical module concept. The comparison between the two concepts indicates that their thermal behaviour in case of LOCA is very similar, although the cylindrical modules concept reaches slightly higher temperatures.
... 1424. [10 ] M. Dalle Donne et al., Conceptual design of a helium-cooled solid breeder blanket... more ... 1424. [10 ] M. Dalle Donne et al., Conceptual design of a helium-cooled solid breeder blanket based on the use of a mixed bed of beryllium and LiaSiO 4 pebbles, Proceedings SOF'I'-17, Rome, 1992 (Elsevier, Amsterdam, 1993) pp. 1326. ... [14 ] H. Feuerstein et al., Behaviour of ...
The potential sources of tritium contamination of the helium-coolant of ceramic breeder blankets ... more The potential sources of tritium contamination of the helium-coolant of ceramic breeder blankets have been evaluated in a previous paper for the specific case of the European BIT DEMO blanket. This evaluation associated with a rough assessment of the permeability to tritium of the tubing of helium-heated steam generators confirmed that the control of tritium losses to the steam circuit is a critical issue for this class of blanket requiring developments in three areas: (1) permeation barriers, (2) tritium recovery processes maintaining a very low concentration in tritiated species in the coolant, and (3) methods for controlling the chemistry of the coolant. Consequently, in order to define the specifications of these developments, a detailed evaluation of the permeability to tritium of helium-heated steam generators (SGs) was performed, which will be reported in this paper. This study includes the definition of the thermal-hydraulic operating conditions of the SGs through thermodynamic cycle calculations, and its thermal-hydraulic design. The obtained geometry, area and temperature profiles along the tubes are then used to estimate, based on relevant permeability data, the tritium permeation through the SG as a function of the composition in tritiated species of the coolant. The implications of these results, in termsmore » of requirements for the considered tritium control methods, will also be discussed on the basis of expected limits in tritium release to the steam circuit.« less
In the frame of the recent CEA studies aiming at - the development, evaluation and comparison of ... more In the frame of the recent CEA studies aiming at - the development, evaluation and comparison of solid breeder blanket concepts in view of their adaptation to NET
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